Interruptions in the sugar-phosphate backbone of DNA.
Interruptions in the sugar-phosphate backbone of DNA, across both strands adjacently.
Interruptions in one of the strands of the sugar-phosphate backbone of double-stranded DNA.
Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.
The reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule which contained damaged regions. The major repair mechanisms are excision repair, in which defective regions in one strand are excised and resynthesized using the complementary base pairing information in the intact strand; photoreactivation repair, in which the lethal and mutagenic effects of ultraviolet light are eliminated; and post-replication repair, in which the primary lesions are not repaired, but the gaps in one daughter duplex are filled in by incorporation of portions of the other (undamaged) daughter duplex. Excision repair and post-replication repair are sometimes referred to as "dark repair" because they do not require light.
Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.
A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.
A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.
A Rec A recombinase found in eukaryotes. Rad51 is involved in DNA REPAIR of double-strand breaks.
Immunologically detectable substances found in the CELL NUCLEUS.
The repair of DOUBLE-STRAND DNA BREAKS by rejoining the broken ends of DNA to each other directly.
A group of PROTEIN-SERINE-THREONINE KINASES which activate critical signaling cascades in double strand breaks, APOPTOSIS, and GENOTOXIC STRESS such as ionizing ultraviolet A light, thereby acting as a DNA damage sensor. These proteins play a role in a wide range of signaling mechanisms in cell cycle control.
Penetrating, high-energy electromagnetic radiation emitted from atomic nuclei during NUCLEAR DECAY. The range of wavelengths of emitted radiation is between 0.1 - 100 pm which overlaps the shorter, more energetic hard X-RAYS wavelengths. The distinction between gamma rays and X-rays is based on their radiation source.
A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.
Repair of DNA DAMAGE by exchange of DNA between matching sequences, usually between the allelic DNA (ALLELES) of sister chromatids.
DNA TOPOISOMERASES that catalyze ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. These enzymes bring about relaxation of the supercoiled DNA and resolution of a knotted circular DNA duplex.
Enzymes that are involved in the reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule, which contained damaged regions.
An aminoacridine derivative that intercalates into DNA and is used as an antineoplastic agent.
Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.
Enzymes that catalyze the transfer of multiple ADP-RIBOSE groups from nicotinamide-adenine dinucleotide (NAD) onto protein targets, thus building up a linear or branched homopolymer of repeating ADP-ribose units i.e., POLY ADENOSINE DIPHOSPHATE RIBOSE.
Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.
Poly(deoxyribonucleotide):poly(deoxyribonucleotide)ligases. Enzymes that catalyze the joining of preformed deoxyribonucleotides in phosphodiester linkage during genetic processes during repair of a single-stranded break in duplex DNA. The class includes both EC 6.5.1.1 (ATP) and EC 6.5.1.2 (NAD).
A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
Compounds that inhibit the activity of DNA TOPOISOMERASE II. Included in this category are a variety of ANTINEOPLASTIC AGENTS which target the eukaryotic form of topoisomerase II and ANTIBACTERIAL AGENTS which target the prokaryotic form of topoisomerase II.
A family of enzymes that catalyze the exonucleolytic cleavage of DNA. It includes members of the class EC 3.1.11 that produce 5'-phosphomonoesters as cleavage products.
A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.
Gene rearrangement of the B-lymphocyte which results in a substitution in the type of heavy-chain constant region that is expressed. This allows the effector response to change while the antigen binding specificity (variable region) remains the same. The majority of class switching occurs by a DNA recombination event but it also can take place at the level of RNA processing.
An increased tendency of the GENOME to acquire MUTATIONS when various processes involved in maintaining and replicating the genome are dysfunctional.
Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.
Acridines which are substituted in any position by one or more amino groups or substituted amino groups.
ELECTROMAGNETIC RADIATION or particle radiation (high energy ELEMENTARY PARTICLES) capable of directly or indirectly producing IONS in its passage through matter. The wavelengths of ionizing electromagnetic radiation are equal to or smaller than those of short (far) ultraviolet radiation and include gamma and X-rays.
An exchange of DNA between matching or similar sequences.
The process by which a DNA molecule is duplicated.
A semisynthetic derivative of PODOPHYLLOTOXIN that exhibits antitumor activity. Teniposide inhibits DNA synthesis by forming a complex with topoisomerase II and DNA. This complex induces breaks in double stranded DNA and prevents repair by topoisomerase II binding. Accumulated breaks in DNA prevent cells from entering into the mitotic phase of the cell cycle, and lead to cell death. Teniposide acts primarily in the G2 and S phases of the cycle.
Deoxyribonucleic acid that makes up the genetic material of fungi.
Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.
A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Enzymes that catalyze the hydrolysis of the internal bonds and thereby the formation of polynucleotides or oligonucleotides from ribo- or deoxyribonucleotide chains. EC 3.1.-.
Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
An enzyme that catalyzes the deamination of cytidine, forming uridine. EC 3.5.4.5.
A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.
Compounds that inhibit the activity of DNA TOPOISOMERASE I.
A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.
DNA TOPOISOMERASES that catalyze ATP-independent breakage of one of the two strands of DNA, passage of the unbroken strand through the break, and rejoining of the broken strand. DNA Topoisomerases, Type I enzymes reduce the topological stress in the DNA structure by relaxing the superhelical turns and knotted rings in the DNA helix.
Proteins that are normally involved in holding cellular growth in check. Deficiencies or abnormalities in these proteins may lead to unregulated cell growth and tumor development.
The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.
Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell.
That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.
Established cell cultures that have the potential to propagate indefinitely.
Enzyme activated in response to DNA DAMAGE involved in cell cycle arrest. The gene is located on the long (q) arm of chromosome 22 at position 12.1. In humans it is encoded by the CHEK2 gene.
A topically applied anti-infective agent.
The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.
The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.
A DNA-binding protein that mediates DNA REPAIR of double strand breaks, and HOMOLOGOUS RECOMBINATION.
Enzyme systems containing a single subunit and requiring only magnesium for endonucleolytic activity. The corresponding modification methylases are separate enzymes. The systems recognize specific short DNA sequences and cleave either within, or at a short specific distance from, the recognition sequence to give specific double-stranded fragments with terminal 5'-phosphates. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 3.1.21.4.
Compounds with triple bonds to each side of a double bond. Many of these are CYTOTOXINS and are researched for use as CYTOTOXIC ANTIBIOTICS.
A chromosome instability syndrome resulting from a defective response to DNA double-strand breaks. In addition to characteristic FACIES and MICROCEPHALY, patients have a range of findings including RADIOSENSITIVITY, immunodeficiency, increased cancer risk, and growth retardation. Causative mutations occur in the NBS1 gene, located on human chromosome 8q21. NBS1 codes for nibrin, the key regulator protein of the R/M/N (RAD50/MRE11/NBS1) protein complex which senses and mediates cellular response to DNA DAMAGE caused by IONIZING RADIATION.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.
An ATP-dependent exodeoxyribonuclease that cleaves in either the 5'- to 3'- or the 3'- to 5'-direction to yield 5'-phosphooligonucleotides. It is primarily found in BACTERIA.
A serine-threonine protein kinase that, when activated by DNA, phosphorylates several DNA-binding protein substrates including the TUMOR SUPPRESSOR PROTEIN P53 and a variety of TRANSCRIPTION FACTORS.
A cross-shaped DNA structure that can be observed under the electron microscope. It is formed by the incomplete exchange of strands between two double-stranded helices or by complementary INVERTED REPEAT SEQUENCES that refold into hairpin loops on opposite strands across from each other.
A family of structurally-related DNA helicases that play an essential role in the maintenance of genome integrity. RecQ helicases were originally discovered in E COLI and are highly conserved across both prokaryotic and eukaryotic organisms. Genetic mutations that result in loss of RecQ helicase activity gives rise to disorders that are associated with CANCER predisposition and premature aging.
Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.
The asymmetrical segregation of genes during replication which leads to the production of non-reciprocal recombinant strands and the apparent conversion of one allele into another. Thus, e.g., the meiotic products of an Aa individual may be AAAa or aaaA instead of AAaa, i.e., the A allele has been converted into the a allele or vice versa.
An alkylating agent in cancer therapy that may also act as a mutagen by interfering with and causing damage to DNA.
Water-soluble, copper-containing low molecular weight polypeptides obtained from the culture medium of Streptomyces verticillus. They are specific inhibitors of DNA synthesis in bacteria and have been found to act as antitumor agents. They have also been used against rust fungi of plants.
A semisynthetic derivative of PODOPHYLLOTOXIN that exhibits antitumor activity. Etoposide inhibits DNA synthesis by forming a complex with topoisomerase II and DNA. This complex induces breaks in double stranded DNA and prevents repair by topoisomerase II binding. Accumulated breaks in DNA prevent entry into the mitotic phase of cell division, and lead to cell death. Etoposide acts primarily in the G2 and S phases of the cell cycle.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
Either of the two longitudinally adjacent threads formed when a eukaryotic chromosome replicates prior to mitosis. The chromatids are held together at the centromere. Sister chromatids are derived from the same chromosome. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
A single-stranded DNA-binding protein that is found in EUKARYOTIC CELLS. It is required for DNA REPLICATION; DNA REPAIR; and GENETIC RECOMBINATION.
A polynucleotide formed from the ADP-RIBOSE moiety of nicotinamide-adenine dinucleotide (NAD) by POLY(ADP-RIBOSE) POLYMERASES.
Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.
A lignan (LIGNANS) found in PODOPHYLLIN resin from the roots of PODOPHYLLUM plants. It is a potent spindle poison, toxic if taken internally, and has been used as a cathartic. It is very irritating to skin and mucous membranes, has keratolytic actions, has been used to treat warts and keratoses, and may have antineoplastic properties, as do some of its congeners and derivatives.
One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
A complex of related glycopeptide antibiotics from Streptomyces verticillus consisting of bleomycin A2 and B2. It inhibits DNA metabolism and is used as an antineoplastic, especially for solid tumors.
Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard X-rays are the higher energy, shorter wavelength X-rays. Soft x-rays or Grenz rays are less energetic and longer in wavelength. The short wavelength end of the X-ray spectrum overlaps the GAMMA RAYS wavelength range. The distinction between gamma rays and X-rays is based on their radiation source.
Recombinases involved in the rearrangement of immunity-related GENES such as IMMUNOGLOBULIN GENES and T-CELL RECEPTOR GENES.
A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.
Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.
The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.
Pyrido-CARBAZOLES originally discovered in the bark of OCHROSIA ELLIPTICA. They inhibit DNA and RNA synthesis and have immunosuppressive properties.
Agents that are capable of inserting themselves between the successive bases in DNA, thus kinking, uncoiling or otherwise deforming it and therefore preventing its proper functioning. They are used in the study of DNA.
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
An autosomal recessive inherited disorder characterized by choreoathetosis beginning in childhood, progressive CEREBELLAR ATAXIA; TELANGIECTASIS of CONJUNCTIVA and SKIN; DYSARTHRIA; B- and T-cell immunodeficiency, and RADIOSENSITIVITY to IONIZING RADIATION. Affected individuals are prone to recurrent sinobronchopulmonary infections, lymphoreticular neoplasms, and other malignancies. Serum ALPHA-FETOPROTEINS are usually elevated. (Menkes, Textbook of Child Neurology, 5th ed, p688) The gene for this disorder (ATM) encodes a cell cycle checkpoint protein kinase and has been mapped to chromosome 11 (11q22-q23).
DNA present in neoplastic tissue.
An exchange of segments between the sister chromatids of a chromosome, either between the sister chromatids of a meiotic tetrad or between the sister chromatids of a duplicated somatic chromosome. Its frequency is increased by ultraviolet and ionizing radiation and other mutagenic agents and is particularly high in BLOOM SYNDROME.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
The phosphoprotein encoded by the BRCA1 gene (GENE, BRCA1). In normal cells the BRCA1 protein is localized in the nucleus, whereas in the majority of breast cancer cell lines and in malignant pleural effusions from breast cancer patients, it is localized mainly in the cytoplasm. (Science 1995;270(5237):713,789-91)
Enzymes which catalyze the hydrolases of ester bonds within DNA. EC 3.1.-.
The period of the CELL CYCLE following DNA synthesis (S PHASE) and preceding M PHASE (cell division phase). The CHROMOSOMES are tetraploid in this point.
The alignment of CHROMOSOMES at homologous sequences.
Nuclear phosphoprotein encoded by the p53 gene (GENES, P53) whose normal function is to control CELL PROLIFERATION and APOPTOSIS. A mutant or absent p53 protein has been found in LEUKEMIA; OSTEOSARCOMA; LUNG CANCER; and COLORECTAL CANCER.
Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.
A cell line derived from cultured tumor cells.
An alkaloid isolated from the stem wood of the Chinese tree, Camptotheca acuminata. This compound selectively inhibits the nuclear enzyme DNA TOPOISOMERASES, TYPE I. Several semisynthetic analogs of camptothecin have demonstrated antitumor activity.
Leukemia L1210 is a designation for a specific murine (mouse) leukemia cell line that was originally isolated from a female mouse with an induced acute myeloid leukemia, which is widely used as a model in cancer research, particularly for in vivo studies of drug efficacy and resistance.
An antiviral antibiotic produced by Cephalosporium aphidicola and other fungi. It inhibits the growth of eukaryotic cells and certain animal viruses by selectively inhibiting the cellular replication of DNA polymerase II or the viral-induced DNA polymerases. The drug may be useful for controlling excessive cell proliferation in patients with cancer, psoriasis or other dermatitis with little or no adverse effect upon non-multiplying cells.
Splitting the DNA into shorter pieces by endonucleolytic DNA CLEAVAGE at multiple sites. It includes the internucleosomal DNA fragmentation, which along with chromatin condensation, are considered to be the hallmarks of APOPTOSIS.
A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Phase of the CELL CYCLE following G1 and preceding G2 when the entire DNA content of the nucleus is replicated. It is achieved by bidirectional replication at multiple sites along each chromosome.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
An autosomal recessive disorder characterized by telangiectatic ERYTHEMA of the face, photosensitivity, DWARFISM and other abnormalities, and a predisposition toward developing cancer. The Bloom syndrome gene (BLM) encodes a RecQ-like DNA helicase.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
A family of recombinases initially identified in BACTERIA. They catalyze the ATP-driven exchange of DNA strands in GENETIC RECOMBINATION. The product of the reaction consists of a duplex and a displaced single-stranded loop, which has the shape of the letter D and is therefore called a D-loop structure.
Proteins that specifically bind to TELOMERES. Proteins in this class include those that perform functions such as telomere capping, telomere maintenance and telomere stabilization.
A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.
Specific loci that show up during KARYOTYPING as a gap (an uncondensed stretch in closer views) on a CHROMATID arm after culturing cells under specific conditions. These sites are associated with an increase in CHROMOSOME FRAGILITY. They are classified as common or rare, and by the specific culture conditions under which they develop. Fragile site loci are named by the letters "FRA" followed by a designation for the specific chromosome, and a letter which refers to which fragile site of that chromosome (e.g. FRAXA refers to fragile site A on the X chromosome. It is a rare, folic acid-sensitive fragile site associated with FRAGILE X SYNDROME.)
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
A site located in the INTRONS at the 5' end of each constant region segment of a immunoglobulin heavy-chain gene where recombination (or rearrangement) occur during IMMUNOGLOBULIN CLASS SWITCHING. Ig switch regions are found on genes encoding all five classes (IMMUNOGLOBULIN ISOTYPES) of IMMUNOGLOBULIN HEAVY CHAINS.
A programmed mutation process whereby changes are introduced to the nucleotide sequence of immunoglobulin gene DNA during development.
Proteins obtained from the species Schizosaccharomyces pombe. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
CELL CYCLE regulatory signaling systems that are triggered by DNA DAMAGE or lack of nutrients during G2 PHASE. When triggered they restrain cells transitioning from G2 phase to M PHASE.
The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes.
Enzymes that recognize CRUCIFORM DNA structures and introduce paired incisions that help to resolve the structure into two DNA helices.
The integration of exogenous DNA into the genome of an organism at sites where its expression can be suitably controlled. This integration occurs as a result of homologous recombination.
The mechanisms effecting establishment, maintenance, and modification of that specific physical conformation of CHROMATIN determining the transcriptional accessibility or inaccessibility of the DNA.
The rate dynamics in chemical or physical systems.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
A large, nuclear protein, encoded by the BRCA2 gene (GENE, BRCA2). Mutations in this gene predispose humans to breast and ovarian cancer. The BRCA2 protein is an essential component of DNA repair pathways, suppressing the formation of gross chromosomal rearrangements. (from Genes Dev. 2000;14(11):1400-6)
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Polyacenes with four ortho-fused benzene rings in a straight linear arrangement. This group is best known for the subclass called TETRACYCLINES.
Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.
A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.
Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation.
An experimental lymphocytic leukemia originally induced in DBA/2 mice by painting with methylcholanthrene.
An antineoplastic agent that inhibits DNA synthesis through the inhibition of ribonucleoside diphosphate reductase.
DNA-dependent DNA polymerases found in bacteria, animal and plant cells. During the replication process, these enzymes catalyze the addition of deoxyribonucleotide residues to the end of a DNA strand in the presence of DNA as template-primer. They also possess exonuclease activity and therefore function in DNA repair.
An in situ method for detecting areas of DNA which are nicked during APOPTOSIS. Terminal deoxynucleotidyl transferase is used to add labeled dUTP, in a template-independent manner, to the 3 prime OH ends of either single- or double-stranded DNA. The terminal deoxynucleotidyl transferase nick end labeling, or TUNEL, assay labels apoptosis on a single-cell level, making it more sensitive than agarose gel electrophoresis for analysis of DNA FRAGMENTATION.
A DNA repair enzyme that catalyzes DNA synthesis during base excision DNA repair. EC 2.7.7.7.
Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.
Proteins found in any species of fungus.
Elements of limited time intervals, contributing to particular results or situations.
A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.
A DNA repair enzyme that catalyses the excision of ribose residues at apurinic and apyrimidinic DNA sites that can result from the action of DNA GLYCOSYLASES. The enzyme catalyzes a beta-elimination reaction in which the C-O-P bond 3' to the apurinic or apyrimidinic site in DNA is broken, leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate. This enzyme was previously listed under EC 3.1.25.2.
Genes that code for proteins that regulate the CELL DIVISION CYCLE. These genes form a regulatory network that culminates in the onset of MITOSIS by activating the p34cdc2 protein (PROTEIN P34CDC2).
Chemical substances, produced by microorganisms, inhibiting or preventing the proliferation of neoplasms.
Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.
Genes and gene segments encoding the IMMUNOGLOBULIN HEAVY CHAINS. Gene segments of the heavy chain genes are symbolized V (variable), D (diversity), J (joining), and C (constant).
Macromolecular complexes formed from the association of defined protein subunits.
The ability of some cells or tissues to survive lethal doses of IONIZING RADIATION. Tolerance depends on the species, cell type, and physical and chemical variables, including RADIATION-PROTECTIVE AGENTS and RADIATION-SENSITIZING AGENTS.
Endonucleases that remove 5' DNA sequences from a DNA structure called a DNA flap. The DNA flap structure occurs in double-stranded DNA containing a single-stranded break where the 5' portion of the downstream strand is too long and overlaps the 3' end of the upstream strand. Flap endonucleases cleave the downstream strand of the overlap flap structure precisely after the first base-paired nucleotide, creating a ligatable nick.
Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.
An antineoplastic antibiotic produced by Streptomyces caespitosus. It is one of the bi- or tri-functional ALKYLATING AGENTS causing cross-linking of DNA and inhibition of DNA synthesis.
Family of retrovirus-associated DNA sequences (myc) originally isolated from an avian myelocytomatosis virus. The proto-oncogene myc (c-myc) codes for a nuclear protein which is involved in nucleic acid metabolism and in mediating the cellular response to growth factors. Truncation of the first exon, which appears to regulate c-myc expression, is crucial for tumorigenicity. The human c-myc gene is located at 8q24 on the long arm of chromosome 8.
Highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning. Many are used as antineoplastic agents, but most are very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. They have also been used as components in poison gases.
An antimitotic agent with immunosuppressive properties.
Deoxyribonucleic acid that makes up the genetic material of bacteria.
Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity.
Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of MAMMALS.
An error-prone mechanism or set of functions for repairing damaged microbial DNA. SOS functions (a concept reputedly derived from the SOS of the international distress signal) are involved in DNA repair and mutagenesis, in cell division inhibition, in recovery of normal physiological conditions after DNA repair, and possibly in cell death when DNA damage is extensive.
Defective nuclei produced during the TELOPHASE of MITOSIS or MEIOSIS by lagging CHROMOSOMES or chromosome fragments derived from spontaneous or experimentally induced chromosomal structural changes.
The termination of the cell's ability to carry out vital functions such as metabolism, growth, reproduction, responsiveness, and adaptability.
Induction and quantitative measurement of chromosomal damage leading to the formation of micronuclei (MICRONUCLEI, CHROMOSOME-DEFECTIVE) in cells which have been exposed to genotoxic agents or IONIZING RADIATION.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Electrophoresis in which agar or agarose gel is used as the diffusion medium.
Enzymes that catalyze the incorporation of deoxyribonucleotides into a chain of DNA. EC 2.7.7.-.
CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.
Regulatory signaling systems that control the progression through the CELL CYCLE. They ensure that the cell has completed, in the correct order and without mistakes, all the processes required to replicate the GENOME and CYTOPLASM, and divide them equally between two daughter cells. If cells sense they have not completed these processes or that the environment does not have the nutrients and growth hormones in place to proceed, then the cells are restrained (or "arrested") until the processes are completed and growth conditions are suitable.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.
Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.
Molecules on the surface of B- and T-lymphocytes that recognize and combine with specific antigens.
A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.
A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.
The relationship between the dose of an administered drug and the response of the organism to the drug.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
Substances that inhibit or prevent the proliferation of NEOPLASMS.
A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.
An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease ARGININOSUCCINIC ACIDURIA in man. EC 4.3.2.1.
An enediyne that alkylates DNA and RNA like MITOMYCIN does, so it is cytotoxic.
Susceptibility of chromosomes to breakage leading to translocation; CHROMOSOME INVERSION; SEQUENCE DELETION; or other CHROMOSOME BREAKAGE related aberrations.
Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)
The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.
White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.
The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.
The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
The functional hereditary units of FUNGI.
Small double-stranded, non-protein coding RNAs (21-31 nucleotides) involved in GENE SILENCING functions, especially RNA INTERFERENCE (RNAi). Endogenously, siRNAs are generated from dsRNAs (RNA, DOUBLE-STRANDED) by the same ribonuclease, Dicer, that generates miRNAs (MICRORNAS). The perfect match of the siRNAs' antisense strand to their target RNAs mediates RNAi by siRNA-guided RNA cleavage. siRNAs fall into different classes including trans-acting siRNA (tasiRNA), repeat-associated RNA (rasiRNA), small-scan RNA (scnRNA), and Piwi protein-interacting RNA (piRNA) and have different specific gene silencing functions.
Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.
Proteins obtained from ESCHERICHIA COLI.
Antineoplastic antibiotic obtained from Streptomyces peucetius. It is a hydroxy derivative of DAUNORUBICIN.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
Nuclear antigen with a role in DNA synthesis, DNA repair, and cell cycle progression. PCNA is required for the coordinated synthesis of both leading and lagging strands at the replication fork during DNA replication. PCNA expression correlates with the proliferation activity of several malignant and non-malignant cell types.
Human COLORECTAL CARCINOMA cell line.
Agents obtained from higher plants that have demonstrable cytostatic or antineoplastic activity.
Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.
The complete gene complement contained in a set of chromosomes in a fungus.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
The period of the CELL CYCLE preceding DNA REPLICATION in S PHASE. Subphases of G1 include "competence" (to respond to growth factors), G1a (entry into G1), G1b (progression), and G1c (assembly). Progression through the G1 subphases is effected by limiting growth factors, nutrients, or inhibitors.
A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.

Prediction of radiosensitivity in human bladder cell lines using nuclear chromatin phenotype. (1/212)

BACKGROUND: Nuclear texture analysis measures phenotypic changes in chromatin distribution within a cell nucleus, while the alkaline Comet assay is a sensitive method for measuring the extent of DNA breakage in individual cells. The authors aim to use both methods to provide information about the sensitivity of cells to ionizing radiation. METHODS: The alkaline Comet assay was performed on six human bladder carcinoma cell lines and one human urothelial cell line exposed to gamma-radiation doses from 0 to 10 Gy. Nuclear chromatin texture analysis of 40 features was then performed in the same cell lines exposed to 0, 2, and 6 Gy to explore if nuclear phenotype was related to radiation sensitivity. RESULTS: Comet assay results demonstrated that the cell lines exhibited different levels of radiosensitivity and could be divided into a radiosensitive and a radioresistant group at >6 Gy. Using stepwise discriminant analysis, a subset of important nuclear texture features that best discriminated between sensitive and resistant cell lines were identified A classification function, defined using these features, correctly classified 81.75% of all cells into their radiosensitive or radioresistant groups based on their pretreatment chromatin phenotype. Posttreatment chromatin changes also varied between cell lines, with sensitive cell lines showing a relaxed chromatin conformation following radiation, whereas resistant cell lines exhibited chromatin condensation. CONCLUSIONS: The authors conclude that the alkaline Comet assay and nuclear texture methodologies may prove to be valuable aids in predicting the response of tumor cells to radiotherapy.  (+info)

Flow cytometric analysis of phosphorylated histone H2AX following exposure to ionizing radiation in human microvascular endothelial cells. (2/212)

We applied a flow cytometric method to quantify IR-induced histone H2AX phosphorylation at serine 139 (gammaH2AX) and compared those values to those obtained using a standard microscopy based foci counting method. After PFA fixation, methanol permeabilization was suitable for both FITC- or Alexa647-gammaH2AX. In contrast, Alexa647-gammaH2AX was not suitable for ethanol permeabilization. Antibody concentrations at 1-2 microg/ml yielded the highest gammaH2AX positive percentage for both antibodies. Without DAPI staining, gammaH2AX formation can be measured as a relative fold increase. Values determined by bivariant flow cytometric analysis and those obtained using microscopic foci formation exhibited a good quantitative correlation. Values obtained by both methods could vary according to the gating or threshold setting used. gammaH2AX positive cells increased as a function of radiation dose (2-16 Gy) followed by a dose-dependent decay. The free radical scavenger N-acetyl-L-cysteine (NAC), if administered at a concentration of 4 mM 30 min before IR, was effective in reducing IR-induced gammaH2AX formation in all phases of the cell cycle. We have developed a simplified and quantitative flow cytometry based method to measure IR-induced gammaH2AX in cells and demonstrated strong correlation to values obtained by a standard automated digital microscopic foci analysis along with NIH ImageJ custom macro software.  (+info)

Sequence determinants of breakpoint location during HIV-1 intersubtype recombination. (3/212)

Retroviral recombination results from strand switching, during reverse transcription, between the two copies of genomic RNA present in the virus. We analysed recombination in part of the envelope gene, between HIV-1 subtype A and D strains. After a single infection cycle, breakpoints clustered in regions corresponding to the constant portions of Env. With some exceptions, a similar distribution was observed after multiple infection cycles, and among recombinant sequences in the HIV Sequence Database. We compared the experimental data with computer simulations made using a program that only allows recombination to occur whenever an identical base is present in the aligned parental RNAs. Experimental recombination was more frequent than expected on the basis of simulated recombination when, in a region spanning 40 nt from the 5' border of a breakpoint, no more than two discordant bases between the parental RNAs were present. When these requirements were not fulfilled, breakpoints were distributed randomly along the RNA, closer to the distribution predicted by computer simulation. A significant preference for recombination was also observed for regions containing homopolymeric stretches. These results define, for the first time, local sequence determinants for recombination between divergent HIV-1 isolates.  (+info)

Nucleotide-resolution mapping of topoisomerase-mediated and apoptotic DNA strand scissions at or near an MLL translocation hotspot. (4/212)

The emergence of therapy-related acute myeloid leukemia (t-AML) has been associated with DNA topoisomerase II (TOP2)-targeted drug treatments and chromosomal translocations frequently involving the MLL, or ALL-1, gene. Two distinct mechanisms have been implicated as potential triggers of t-AML translocations: TOP2-mediated DNA cleavage and apoptotic higher-order chromatin fragmentation. Assessment of the role of TOP2 in this process has been hampered by a lack of techniques allowing in vivo mapping of TOP2-mediated DNA cleavage at nucleotide resolution in single-copy genes. A novel method, extension ligation-mediated polymerase chain reaction (ELMPCR), was used here for mapping topoisomerase-mediated DNA strand breaks and apoptotic DNA cleavage across a translocation-prone region of MLL in human cells. We report the first genomic map integrating translocation breakpoints and topoisomerase I, TOP2, and apoptotic DNA cleavage sites at nucleotide resolution across an MLL region harboring a t-AML translocation hotspot. This hotspot is flanked by a TOP2 cleavage site and is localized at one extremity of a minor apoptotic cleavage region, where multiple single- and double-strand breaks were induced by caspase-activated apoptotic nucleases. This cleavage pattern was in sharp contrast to that observed approximately 200 bp downstream in the exon 12 region, which displayed much stronger apoptotic cleavage but where no double-strand breaks were detected and no t-AML-associated breakpoints were reported. The localization and remarkable clustering of the t-AML breakpoints cannot be explained simply by the DNA cleavage patterns but might result from potential interactions between TOP2 poisoning, apoptotic DNA cleavage, and DNA repair attempts at specific sites of higher-order chromatin structure in apoptosis-evading cells. ELMPCR provides a new tool for investigating the role of DNA topoisomerases in fundamental genetic processes and translocations associated with cancer treatments involving topoisomerase-targeted drugs.  (+info)

Atypical haemolytic uraemic syndrome associated with a hybrid complement gene. (5/212)

BACKGROUND: Sequence analysis of the regulators of complement activation (RCA) cluster of genes at chromosome position 1q32 shows evidence of several large genomic duplications. These duplications have resulted in a high degree of sequence identity between the gene for factor H (CFH) and the genes for the five factor H-related proteins (CFHL1-5; aliases CFHR1-5). CFH mutations have been described in association with atypical haemolytic uraemic syndrome (aHUS). The majority of the mutations are missense changes that cluster in the C-terminal region and impair the ability of factor H to regulate surface-bound C3b. Some have arisen as a result of gene conversion between CFH and CFHL1. In this study we tested the hypothesis that nonallelic homologous recombination between low-copy repeats in the RCA cluster could result in the formation of a hybrid CFH/CFHL1 gene that predisposes to the development of aHUS. METHODS AND FINDINGS: In a family with many cases of aHUS that segregate with the RCA cluster we used cDNA analysis, gene sequencing, and Southern blotting to show that affected individuals carry a heterozygous CFH/CFHL1 hybrid gene in which exons 1-21 are derived from CFH and exons 22/23 from CFHL1. This hybrid encodes a protein product identical to a functionally significant CFH mutant (c.3572C>T, S1191L and c.3590T>C, V1197A) that has been previously described in association with aHUS. CONCLUSIONS: CFH mutation screening is recommended in all aHUS patients prior to renal transplantation because of the high risk of disease recurrence post-transplant in those known to have a CFH mutation. Because of our finding it will be necessary to implement additional screening strategies that will detect a hybrid CFH/CFHL1 gene.  (+info)

Chk2 mediates stabilization of the FoxM1 transcription factor to stimulate expression of DNA repair genes. (6/212)

The forkhead box M1 (FoxM1) transcription factor regulates expression of cell cycle genes essential for DNA replication and mitosis during organ repair and cancer progression. Here, we demonstrate that FoxM1-deficient (-/-) mouse embryonic fibroblasts and osteosarcoma U2OS cells depleted in FoxM1 levels by small interfering RNA transfection display increased DNA breaks, as evidenced by immunofluorescence focus staining for phosphospecific histone H2AX. FoxM1-deficient cells also exhibit stimulation of p53 transcriptional activity, as evidenced by increased expression of the p21(cip1) gene. FoxM1-deficient cells display reduced expression of the base excision repair factor X-ray cross-complementing group 1 (XRCC1) and breast cancer-associated gene 2 (BRCA2), the latter of which is involved in homologous recombination repair of DNA double-strand breaks. Furthermore, FoxM1 protein is phosphorylated by checkpoint kinase 2 (Chk2) in response to DNA damage. This phosphorylation of FoxM1 on serine residue 361 caused increased stability of the FoxM1 protein with corresponding increased transcription of XRCC1 and BRCA2 genes, both of which are required for repair of DNA damage. These results identify a novel role for FoxM1 in the transcriptional response during DNA damage/checkpoint signaling and show a novel mechanism by which Chk2 protein regulates expression of DNA repair enzymes.  (+info)

Methylating agents and DNA repair responses: Methylated bases and sources of strand breaks. (7/212)

The chemical methylating agents methylmethane sulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) have been used for decades as classical DNA damaging agents. These agents have been utilized to uncover and explore pathways of DNA repair, DNA damage response, and mutagenesis. MMS and MNNG modify DNA by adding methyl groups to a number of nucleophilic sites on the DNA bases, although MNNG produces a greater percentage of O-methyl adducts. There has been substantial progress elucidating direct reversal proteins that remove methyl groups and base excision repair (BER), which removes and replaces methylated bases. Direct reversal proteins and BER, thus, counteract the toxic, mutagenic, and clastogenic effects of methylating agents. Despite recent progress, the complexity of DNA damage responses to methylating agents is still being discovered. In particular, there is growing understanding of pathways such as homologous recombination, lesion bypass, and mismatch repair that react when the response of direct reversal proteins and BER is insufficient. Furthermore, the importance of proper balance within the steps in BER has been uncovered with the knowledge that DNA structural intermediates during BER are deleterious. A number of issues complicate the elucidation of the downstream responses when direct reversal is insufficient or BER is imbalanced. These include inter-species differences, cell-type-specific differences within mammals and between cancer cell lines, and the type of methyl damage or BER intermediate encountered. MMS also carries a misleading reputation of being a radiomimetic, that is, capable of directly producing strand breaks. This review focuses on the DNA methyl damage caused by MMS and MNNG for each site of potential methylation to summarize what is known about the repair of such damage and the downstream responses and consequences if the damage is not repaired.  (+info)

Topoisomerase II-mediated breaks in spermatozoa cause the specific degradation of paternal DNA in fertilized oocytes. (8/212)

We have demonstrated that mouse spermatozoa can cleave their DNA into 50-kb fragments when treated with Triton X-100, MnCl(2), and CaCl(2). This cleavage, which is termed sperm chromatin fragmentation (SCF), is mediated by topoisomerase IIB (TOP2B) following stimulation by a factor in the epididymal fluid, most likely a nuclease, and can be at least partially religated by EDTA. When the protamines are removed, this DNA breakage is followed by digestion of the DNA by a nuclease(s). We tested whether the oocyte could repair TOP2B-induced sperm DNA breaks and whether partial religation by EDTA would allow spermatozoa to fertilize the oocytes normally. Oocytes injected with untreated spermatozoa developed normally. However, oocytes injected with spermatozoa treated with MnCl(2) and CaCl(2) to induce SCF, with or without subsequent EDTA treatment, failed to develop. In both of these treatment groups, the maternal pronuclei developed normally and replicated their DNA. However the paternal pronuclei did not replicate their DNA and this DNA began to disappear 6 h postinjection, which corresponded approximately to the time at which maternal DNA replication was initiated. These data suggest that when TOP2B is induced to cleave sperm DNA before fertilization, the paternal DNA is subsequently degraded by a highly regulated mechanism that does not affect the maternal chromatin. Furthermore, partial religation by EDTA of TOP2B-induced breaks prevents neither the inhibition of DNA synthesis nor DNA degradation.  (+info)

DNA breaks refer to any damage or disruption in the DNA molecule that results in a separation of the double helix strands. There are two types of DNA breaks: single-strand breaks (SSBs) and double-strand breaks (DSBs).

Single-strand breaks occur when one of the two strands in the DNA duplex is cleaved, leaving the other strand intact. These breaks are usually repaired quickly and efficiently by enzymes that can recognize and repair the damage.

Double-strand breaks, on the other hand, are more serious forms of DNA damage because they result in a complete separation of both strands of the DNA duplex. DSBs can lead to genomic instability, chromosomal aberrations, and cell death if not repaired promptly and accurately.

DSBs can be caused by various factors, including ionizing radiation, chemotherapeutic agents, oxidative stress, and errors during DNA replication or repair. The body has several mechanisms to repair DSBs, including non-homologous end joining (NHEJ) and homologous recombination (HR). However, if these repair pathways are impaired or overwhelmed, DSBs can lead to mutations, cancer, and other diseases.

Double-stranded DNA breaks (DSBs) refer to a type of damage that occurs in the DNA molecule when both strands of the double helix are severed or broken at the same location. This kind of damage is particularly harmful to cells because it can disrupt the integrity and continuity of the genetic material, potentially leading to genomic instability, mutations, and cell death if not properly repaired.

DSBs can arise from various sources, including exposure to ionizing radiation, chemical agents, free radicals, reactive oxygen species (ROS), and errors during DNA replication or repair processes. Unrepaired or incorrectly repaired DSBs have been implicated in numerous human diseases, such as cancer, neurodegenerative disorders, and premature aging.

Cells possess several mechanisms to repair double-stranded DNA breaks, including homologous recombination (HR) and non-homologous end joining (NHEJ). HR is a more accurate repair pathway that uses a homologous template, typically the sister chromatid, to restore the original DNA sequence. NHEJ, on the other hand, directly ligates the broken ends together, often resulting in small deletions or insertions at the break site and increased risk of errors. The choice between these two pathways depends on various factors, such as the cell cycle stage, the presence of nearby breaks, and the availability of repair proteins.

In summary, double-stranded DNA breaks are severe forms of DNA damage that can have detrimental consequences for cells if not properly repaired. Cells employ multiple mechanisms to address DSBs, with homologous recombination and non-homologous end joining being the primary repair pathways.

Single-stranded DNA breaks (SSBs) refer to a type of DNA damage in which one strand of the double-helix structure is cleaved or broken. This kind of damage can occur spontaneously due to cellular metabolism or can be induced by various genotoxic agents, such as ionizing radiation and certain chemicals.

SSBs are typically repaired rapidly and efficiently by enzymes known as DNA repair proteins. However, if left unrepaired or misrepaired, they can lead to mutations, genomic instability, and increased risk of diseases, including cancer. In some cases, single-stranded breaks may also precede the formation of more severe double-stranded DNA breaks (DSBs).

It is important to note that while SSBs are less catastrophic than DSBs, they still play a significant role in genome maintenance and cellular health.

DNA damage refers to any alteration in the structure or composition of deoxyribonucleic acid (DNA), which is the genetic material present in cells. DNA damage can result from various internal and external factors, including environmental exposures such as ultraviolet radiation, tobacco smoke, and certain chemicals, as well as normal cellular processes such as replication and oxidative metabolism.

Examples of DNA damage include base modifications, base deletions or insertions, single-strand breaks, double-strand breaks, and crosslinks between the two strands of the DNA helix. These types of damage can lead to mutations, genomic instability, and chromosomal aberrations, which can contribute to the development of diseases such as cancer, neurodegenerative disorders, and aging-related conditions.

The body has several mechanisms for repairing DNA damage, including base excision repair, nucleotide excision repair, mismatch repair, and double-strand break repair. However, if the damage is too extensive or the repair mechanisms are impaired, the cell may undergo apoptosis (programmed cell death) to prevent the propagation of potentially harmful mutations.

DNA repair is the process by which cells identify and correct damage to the DNA molecules that encode their genome. DNA can be damaged by a variety of internal and external factors, such as radiation, chemicals, and metabolic byproducts. If left unrepaired, this damage can lead to mutations, which may in turn lead to cancer and other diseases.

There are several different mechanisms for repairing DNA damage, including:

1. Base excision repair (BER): This process repairs damage to a single base in the DNA molecule. An enzyme called a glycosylase removes the damaged base, leaving a gap that is then filled in by other enzymes.
2. Nucleotide excision repair (NER): This process repairs more severe damage, such as bulky adducts or crosslinks between the two strands of the DNA molecule. An enzyme cuts out a section of the damaged DNA, and the gap is then filled in by other enzymes.
3. Mismatch repair (MMR): This process repairs errors that occur during DNA replication, such as mismatched bases or small insertions or deletions. Specialized enzymes recognize the error and remove a section of the newly synthesized strand, which is then replaced by new nucleotides.
4. Double-strand break repair (DSBR): This process repairs breaks in both strands of the DNA molecule. There are two main pathways for DSBR: non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ directly rejoins the broken ends, while HR uses a template from a sister chromatid to repair the break.

Overall, DNA repair is a crucial process that helps maintain genome stability and prevent the development of diseases caused by genetic mutations.

Genetic recombination is the process by which genetic material is exchanged between two similar or identical molecules of DNA during meiosis, resulting in new combinations of genes on each chromosome. This exchange occurs during crossover, where segments of DNA are swapped between non-sister homologous chromatids, creating genetic diversity among the offspring. It is a crucial mechanism for generating genetic variability and facilitating evolutionary change within populations. Additionally, recombination also plays an essential role in DNA repair processes through mechanisms such as homologous recombinational repair (HRR) and non-homologous end joining (NHEJ).

The Comet Assay, also known as single-cell gel electrophoresis (SCGE), is a sensitive method used to detect and measure DNA damage at the level of individual cells. The assay gets its name from the comet-like shape that formed DNA fragments migrate towards the anode during electrophoresis, creating a "tail" that represents the damaged DNA.

In this assay, cells are embedded in low melting point agarose on a microscope slide and then lysed to remove the cell membranes and histones, leaving the DNA intact. The slides are then subjected to electrophoresis under neutral or alkaline conditions, which causes the negatively charged DNA fragments to migrate out of the nucleus towards the anode. After staining with a DNA-binding dye, the slides are visualized under a fluorescence microscope and the degree of DNA damage is quantified by measuring the length and intensity of the comet "tail."

The Comet Assay is widely used in genetic toxicology to assess the genotoxic potential of chemicals, drugs, and environmental pollutants. It can also be used to measure DNA repair capacity and oxidative DNA damage.

Chromosome breakage is a medical term that refers to the breaking or fragmentation of chromosomes, which are thread-like structures located in the nucleus of cells that carry genetic information. Normally, chromosomes are tightly coiled and consist of two strands called chromatids, joined together at a central point called the centromere.

Chromosome breakage can occur spontaneously or be caused by environmental factors such as radiation or chemicals, or inherited genetic disorders. When a chromosome breaks, it can result in various genetic abnormalities, depending on the location and severity of the break.

For instance, if the break occurs in a region containing important genes, it can lead to the loss or alteration of those genes, causing genetic diseases or birth defects. In some cases, the broken ends of the chromosome may rejoin incorrectly, leading to chromosomal rearrangements such as translocations, deletions, or inversions. These rearrangements can also result in genetic disorders or cancer.

Chromosome breakage is commonly observed in individuals with certain inherited genetic conditions, such as Bloom syndrome, Fanconi anemia, and ataxia-telangiectasia, which are characterized by an increased susceptibility to chromosome breakage due to defects in DNA repair mechanisms.

Deoxyribonucleic acid (DNA) is the genetic material present in the cells of organisms where it is responsible for the storage and transmission of hereditary information. DNA is a long molecule that consists of two strands coiled together to form a double helix. Each strand is made up of a series of four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - that are linked together by phosphate and sugar groups. The sequence of these bases along the length of the molecule encodes genetic information, with A always pairing with T and C always pairing with G. This base-pairing allows for the replication and transcription of DNA, which are essential processes in the functioning and reproduction of all living organisms.

DNA-binding proteins are a type of protein that have the ability to bind to DNA (deoxyribonucleic acid), the genetic material of organisms. These proteins play crucial roles in various biological processes, such as regulation of gene expression, DNA replication, repair and recombination.

The binding of DNA-binding proteins to specific DNA sequences is mediated by non-covalent interactions, including electrostatic, hydrogen bonding, and van der Waals forces. The specificity of binding is determined by the recognition of particular nucleotide sequences or structural features of the DNA molecule.

DNA-binding proteins can be classified into several categories based on their structure and function, such as transcription factors, histones, and restriction enzymes. Transcription factors are a major class of DNA-binding proteins that regulate gene expression by binding to specific DNA sequences in the promoter region of genes and recruiting other proteins to modulate transcription. Histones are DNA-binding proteins that package DNA into nucleosomes, the basic unit of chromatin structure. Restriction enzymes are DNA-binding proteins that recognize and cleave specific DNA sequences, and are widely used in molecular biology research and biotechnology applications.

Rad51 recombinase is a protein involved in the repair of double-stranded DNA breaks through homologous recombination, a process that helps maintain genomic stability. This protein forms a nucleoprotein filament on single-stranded DNA, facilitating the search for and invasion of homologous sequences in double-stranded DNA. Rad51 recombinase is highly conserved across various species, including humans, and plays a crucial role in preventing genetic disorders, cancer, and aging caused by DNA damage.

Nuclear antigens are proteins or other molecules found in the nucleus of a cell that can stimulate an immune response and produce antibodies when they are recognized as foreign by the body's immune system. These antigens are normally located inside the cell and are not typically exposed to the immune system, but under certain circumstances, such as during cell death or damage, they may be released and become targets of the immune system.

Nuclear antigens can play a role in the development of some autoimmune diseases, such as systemic lupus erythematosus (SLE), where the body's immune system mistakenly attacks its own cells and tissues. In SLE, nuclear antigens such as double-stranded DNA and nucleoproteins are common targets of the abnormal immune response.

Testing for nuclear antigens is often used in the diagnosis and monitoring of autoimmune diseases. For example, a positive test for anti-double-stranded DNA antibodies is a specific indicator of SLE and can help confirm the diagnosis. However, it's important to note that not all people with SLE will have positive nuclear antigen tests, and other factors must also be considered in making a diagnosis.

DNA end-joining repair, also known as non-homologous end joining (NHEJ), is a primary mechanism for repairing double-stranded breaks in DNA. This pathway involves the direct rejoining of broken ends, often with some degree of imprecision, and it can result in small deletions or insertions at the site of the break. NHEJ plays a crucial role in maintaining genomic stability and is an important process for the repair of DNA damage that can occur as a result of ionizing radiation, chemotherapeutic agents, and other sources of genotoxic stress. The key proteins involved in NHEJ include the Ku heterodimer, DNA-dependent protein kinase (DNA-PK), XRCC4, XLF, and DNA ligase IV.

Ataxia telangiectasia mutated (ATM) proteins are a type of protein that play a crucial role in the maintenance and repair of DNA in cells. The ATM gene produces these proteins, which are involved in several important cellular processes such as:

1. DNA damage response: When DNA is damaged, ATM proteins help to detect and respond to the damage by activating various signaling pathways that lead to DNA repair or apoptosis (programmed cell death) if the damage is too severe.
2. Cell cycle regulation: ATM proteins regulate the cell cycle by controlling checkpoints that ensure proper DNA replication and division. This helps prevent the propagation of cells with damaged DNA.
3. Telomere maintenance: ATM proteins help maintain telomeres, which are the protective caps at the ends of chromosomes. Telomeres shorten as cells divide, and when they become too short, cells can no longer divide and enter a state of senescence or die.

Mutations in the ATM gene can lead to Ataxia-telangiectasia (A-T), a rare inherited disorder characterized by neurological problems, immune system dysfunction, increased risk of cancer, and sensitivity to ionizing radiation. People with A-T have defective ATM proteins that cannot properly respond to DNA damage, leading to genomic instability and increased susceptibility to disease.

Gamma rays are a type of ionizing radiation that is released from the nucleus of an atom during radioactive decay. They are high-energy photons, with wavelengths shorter than 0.01 nanometers and frequencies greater than 3 x 10^19 Hz. Gamma rays are electromagnetic radiation, similar to X-rays, but with higher energy levels and the ability to penetrate matter more deeply. They can cause damage to living tissue and are used in medical imaging and cancer treatment.

Single-stranded DNA (ssDNA) is a form of DNA that consists of a single polynucleotide chain. In contrast, double-stranded DNA (dsDNA) consists of two complementary polynucleotide chains that are held together by hydrogen bonds.

In the double-helix structure of dsDNA, each nucleotide base on one strand pairs with a specific base on the other strand through hydrogen bonding: adenine (A) with thymine (T), and guanine (G) with cytosine (C). This base pairing provides stability to the double-stranded structure.

Single-stranded DNA, on the other hand, lacks this complementary base pairing and is therefore less stable than dsDNA. However, ssDNA can still form secondary structures through intrastrand base pairing, such as hairpin loops or cruciform structures.

Single-stranded DNA is found in various biological contexts, including viral genomes, transcription bubbles during gene expression, and in certain types of genetic recombination. It also plays a critical role in some laboratory techniques, such as polymerase chain reaction (PCR) and DNA sequencing.

Recombinational DNA repair is a biological process that takes place in cells to correct damage to the DNA molecule. This type of repair is particularly important in maintaining the stability and integrity of the genetic code, especially in response to double-strand breaks (DSBs) in the DNA.

In recombinational DNA repair, the cell uses a template from a homologous DNA sequence, typically a sister chromatid, to restore the damaged region. The process involves several steps:

1. Resection: The broken ends of the DNA molecule are processed by enzymes that remove nucleotides and create 3' single-stranded overhangs.
2. Recombination: The single-stranded overhangs invade a homologous DNA sequence, forming a displacement loop (D-loop) structure. This invasion is facilitated by recombinase proteins such as Rad51 and Dmc1.
3. Strand exchange: The invading 3' end of the single strand pairs with the complementary sequence in the template DNA, and DNA synthesis occurs using the template to restore the missing genetic information.
4. Resolution: The recombination intermediate is resolved, and the repaired DNA molecule is ligated together. This step can result in different outcomes, including crossover or non-crossover events, depending on the specific mechanisms involved.

Recombinational DNA repair plays a crucial role in maintaining genome stability and preventing mutations that could lead to diseases such as cancer. Additionally, this process is exploited in genetic engineering techniques like homologous recombination-mediated gene targeting and CRISPR-Cas9 genome editing.

DNA topoisomerases are enzymes that regulate the topological state of DNA during various cellular processes such as replication, transcription, and repair. They do this by introducing temporary breaks in the DNA strands and allowing the strands to rotate around each other, thereby relieving torsional stress and supercoiling. Topoisomerases are classified into two types: type I and type II.

Type II topoisomerases are further divided into two subtypes: type IIA and type IIB. These enzymes function by forming a covalent bond with the DNA strands, cleaving them, and then passing another segment of DNA through the break before resealing the original strands. This process allows for the removal of both positive and negative supercoils from DNA as well as the separation of interlinked circular DNA molecules (catenanes) or knotted DNA structures.

Type II topoisomerases are essential for cell viability, and their dysfunction has been linked to various human diseases, including cancer and neurodegenerative disorders. They have also emerged as important targets for the development of anticancer drugs that inhibit their activity and induce DNA damage leading to cell death. Examples of type II topoisomerase inhibitors include etoposide, doxorubicin, and mitoxantrone.

DNA repair enzymes are a group of enzymes that are responsible for identifying and correcting damage to the DNA molecule. These enzymes play a critical role in maintaining the integrity of an organism's genetic material, as they help to ensure that the information stored in DNA is accurately transmitted during cell division and reproduction.

There are several different types of DNA repair enzymes, each responsible for correcting specific types of damage. For example, base excision repair enzymes remove and replace damaged or incorrect bases, while nucleotide excision repair enzymes remove larger sections of damaged DNA and replace them with new nucleotides. Other types of DNA repair enzymes include mismatch repair enzymes, which correct errors that occur during DNA replication, and double-strand break repair enzymes, which are responsible for fixing breaks in both strands of the DNA molecule.

Defects in DNA repair enzymes have been linked to a variety of diseases, including cancer, neurological disorders, and premature aging. For example, individuals with xeroderma pigmentosum, a rare genetic disorder characterized by an increased risk of skin cancer, have mutations in genes that encode nucleotide excision repair enzymes. Similarly, defects in mismatch repair enzymes have been linked to hereditary nonpolyposis colorectal cancer, a type of colon cancer that is inherited and tends to occur at a younger age than sporadic colon cancer.

Overall, DNA repair enzymes play a critical role in maintaining the stability and integrity of an organism's genetic material, and defects in these enzymes can have serious consequences for human health.

Amsacrine is a chemotherapeutic agent, which means it is a medication used to treat cancer. It is classified as an antineoplastic drug, and more specifically, as an intercalating agent and a topoisomerase II inhibitor. Amsacrine works by intercalating, or inserting itself, into the DNA of cancer cells, which prevents the DNA from replicating and ultimately leads to the death of the cancer cell. It is primarily used in the treatment of acute myeloid leukemia (AML) and other hematologic malignancies.

The chemical name for Amsacrine is 5-[3-amino-1-(3-aminopropyl)-2-hydroxybut-1-yloxy]-8-chloro-1,4-naphthoquinone. It has a molecular formula of C16H17ClNO5 and a molecular weight of 359.8 g/mol.

Amsacrine is typically administered intravenously, and its use is usually reserved for patients who have not responded to other forms of chemotherapy. It may be used in combination with other anticancer drugs as part of a treatment regimen. As with any chemotherapeutic agent, Amsacrine can have significant side effects, including nausea, vomiting, and hair loss. It can also cause damage to the heart and other organs, so it is important for patients to be closely monitored during treatment.

It's worth noting that while Amsacrine can be an effective treatment for some types of cancer, it is not a cure-all, and its use must be carefully considered in the context of each individual patient's medical history and current health status.

Cell cycle proteins are a group of regulatory proteins that control the progression of the cell cycle, which is the series of events that take place in a eukaryotic cell leading to its division and duplication. These proteins can be classified into several categories based on their functions during different stages of the cell cycle.

The major groups of cell cycle proteins include:

1. Cyclin-dependent kinases (CDKs): CDKs are serine/threonine protein kinases that regulate key transitions in the cell cycle. They require binding to a regulatory subunit called cyclin to become active. Different CDK-cyclin complexes are activated at different stages of the cell cycle.
2. Cyclins: Cyclins are a family of regulatory proteins that bind and activate CDKs. Their levels fluctuate throughout the cell cycle, with specific cyclins expressed during particular phases. For example, cyclin D is important for the G1 to S phase transition, while cyclin B is required for the G2 to M phase transition.
3. CDK inhibitors (CKIs): CKIs are regulatory proteins that bind to and inhibit CDKs, thereby preventing their activation. CKIs can be divided into two main families: the INK4 family and the Cip/Kip family. INK4 family members specifically inhibit CDK4 and CDK6, while Cip/Kip family members inhibit a broader range of CDKs.
4. Anaphase-promoting complex/cyclosome (APC/C): APC/C is an E3 ubiquitin ligase that targets specific proteins for degradation by the 26S proteasome. During the cell cycle, APC/C regulates the metaphase to anaphase transition and the exit from mitosis by targeting securin and cyclin B for degradation.
5. Other regulatory proteins: Several other proteins play crucial roles in regulating the cell cycle, such as p53, a transcription factor that responds to DNA damage and arrests the cell cycle, and the polo-like kinases (PLKs), which are involved in various aspects of mitosis.

Overall, cell cycle proteins work together to ensure the proper progression of the cell cycle, maintain genomic stability, and prevent uncontrolled cell growth, which can lead to cancer.

Histones are highly alkaline proteins found in the chromatin of eukaryotic cells. They are rich in basic amino acid residues, such as arginine and lysine, which give them their positive charge. Histones play a crucial role in packaging DNA into a more compact structure within the nucleus by forming a complex with it called a nucleosome. Each nucleosome contains about 146 base pairs of DNA wrapped around an octamer of eight histone proteins (two each of H2A, H2B, H3, and H4). The N-terminal tails of these histones are subject to various post-translational modifications, such as methylation, acetylation, and phosphorylation, which can influence chromatin structure and gene expression. Histone variants also exist, which can contribute to the regulation of specific genes and other nuclear processes.

DNA ligases are enzymes that catalyze the formation of a phosphodiester bond between two compatible ends of DNA molecules, effectively joining or "ligating" them together. There are several types of DNA ligases found in nature, each with specific functions and preferences for the type of DNA ends they can seal.

The most well-known DNA ligase is DNA ligase I, which plays a crucial role in replicating and repairing DNA in eukaryotic cells. It seals nicks or gaps in double-stranded DNA during replication and participates in the final step of DNA excision repair by rejoining the repaired strand to the original strand.

DNA ligase IV, another important enzyme, is primarily involved in the repair of double-strand breaks through a process called non-homologous end joining (NHEJ). This pathway is essential for maintaining genome stability and preventing chromosomal abnormalities.

Bacterial DNA ligases, such as T4 DNA ligase, are often used in molecular biology techniques due to their ability to join various types of DNA ends with high efficiency. These enzymes have been instrumental in the development of recombinant DNA technology and gene cloning methods.

Endodeoxyribonucleases are a type of enzyme that cleave, or cut, phosphodiester bonds within the backbone of DNA molecules. These enzymes are also known as restriction endonucleases or simply restriction enzymes. They are called "restriction" enzymes because they were first discovered in bacteria, where they function to protect the organism from foreign DNA by cleaving and destroying invading viral DNA.

Endodeoxyribonucleases recognize specific sequences of nucleotides within the DNA molecule, known as recognition sites or restriction sites, and cut the phosphodiester bonds at specific locations within these sites. The cuts made by endodeoxyribonucleases can be either "sticky" or "blunt," depending on whether the enzyme leaves single-stranded overhangs or creates blunt ends at the site of cleavage, respectively.

Endodeoxyribonucleases are widely used in molecular biology research for various applications, including DNA cloning, genome mapping, and genetic engineering. They allow researchers to cut DNA molecules at specific sites, creating defined fragments that can be manipulated and recombined in a variety of ways.

Topoisomerase II inhibitors are a class of anticancer drugs that work by interfering with the enzyme topoisomerase II, which is essential for DNA replication and transcription. These inhibitors bind to the enzyme-DNA complex, preventing the relaxation of supercoiled DNA and causing DNA strand breaks. This results in the accumulation of double-stranded DNA breaks, which can lead to apoptosis (programmed cell death) in rapidly dividing cells, such as cancer cells. Examples of topoisomerase II inhibitors include etoposide, doxorubicin, and mitoxantrone.

Exodeoxyribonucleases are a type of enzyme that cleave (break) nucleotides from the ends of DNA molecules. They are further classified into 5' exodeoxyribonucleases and 3' exodeoxyribonucleases based on the end of the DNA molecule they act upon.

5' Exodeoxyribonucleases remove nucleotides from the 5' end (phosphate group) of a DNA strand, while 3' exodeoxyribonucleases remove nucleotides from the 3' end (hydroxyl group) of a DNA strand.

These enzymes play important roles in various biological processes such as DNA replication, repair, and degradation. They are also used in molecular biology research for various applications such as DNA sequencing, cloning, and genetic engineering.

Meiosis is a type of cell division that results in the formation of four daughter cells, each with half the number of chromosomes as the parent cell. It is a key process in sexual reproduction, where it generates gametes or sex cells (sperm and eggs).

The process of meiosis involves one round of DNA replication followed by two successive nuclear divisions, meiosis I and meiosis II. In meiosis I, homologous chromosomes pair, form chiasma and exchange genetic material through crossing over, then separate from each other. In meiosis II, sister chromatids separate, leading to the formation of four haploid cells. This process ensures genetic diversity in offspring by shuffling and recombining genetic information during the formation of gametes.

Immunoglobulin class switching, also known as isotype switching or class switch recombination (CSR), is a biological process that occurs in B lymphocytes as part of the adaptive immune response. This mechanism allows a mature B cell to change the type of antibody it produces from one class to another (e.g., from IgM to IgG, IgA, or IgE) while keeping the same antigen-binding specificity.

During immunoglobulin class switching, the constant region genes of the heavy chain undergo a DNA recombination event, which results in the deletion of the original constant region exons and the addition of new constant region exons downstream. This switch allows the B cell to express different effector functions through the production of antibodies with distinct constant regions, tailoring the immune response to eliminate pathogens more effectively. The process is regulated by various cytokines and signals from T cells and is critical for mounting an effective humoral immune response.

Genomic instability is a term used in genetics and molecular biology to describe a state of increased susceptibility to genetic changes or mutations in the genome. It can be defined as a condition where the integrity and stability of the genome are compromised, leading to an increased rate of DNA alterations such as point mutations, insertions, deletions, and chromosomal rearrangements.

Genomic instability is a hallmark of cancer cells and can also be observed in various other diseases, including genetic disorders and aging. It can arise due to defects in the DNA repair mechanisms, telomere maintenance, epigenetic regulation, or chromosome segregation during cell division. These defects can result from inherited genetic mutations, acquired somatic mutations, exposure to environmental mutagens, or age-related degenerative changes.

Genomic instability is a significant factor in the development and progression of cancer as it promotes the accumulation of oncogenic mutations that contribute to tumor initiation, growth, and metastasis. Therefore, understanding the mechanisms underlying genomic instability is crucial for developing effective strategies for cancer prevention, diagnosis, and treatment.

DNA helicases are a group of enzymes that are responsible for separating the two strands of DNA during processes such as replication and transcription. They do this by unwinding the double helix structure of DNA, using energy from ATP to break the hydrogen bonds between the base pairs. This allows other proteins to access the individual strands of DNA and carry out functions such as copying the genetic code or transcribing it into RNA.

During replication, DNA helicases help to create a replication fork, where the two strands of DNA are separated and new complementary strands are synthesized. In transcription, DNA helicases help to unwind the DNA double helix at the promoter region, allowing the RNA polymerase enzyme to bind and begin transcribing the DNA into RNA.

DNA helicases play a crucial role in maintaining the integrity of the genetic code and are essential for the normal functioning of cells. Defects in DNA helicases have been linked to various diseases, including cancer and neurological disorders.

Aminoacridines are a group of synthetic chemical compounds that contain an acridine nucleus, which is a tricyclic aromatic structure, substituted with one or more amino groups. These compounds have been studied for their potential therapeutic properties, particularly as antiseptics and antibacterial agents. However, their use in medicine has declined due to the development of newer and safer antibiotics. Some aminoacridines also exhibit antimalarial, antifungal, and antiviral activities. They can intercalate into DNA, disrupting its structure and function, which is thought to contribute to their antimicrobial effects. However, this property also makes them potentially mutagenic and carcinogenic, limiting their clinical use.

Ionizing radiation is a type of radiation that carries enough energy to ionize atoms or molecules, which means it can knock electrons out of their orbits and create ions. These charged particles can cause damage to living tissue and DNA, making ionizing radiation dangerous to human health. Examples of ionizing radiation include X-rays, gamma rays, and some forms of subatomic particles such as alpha and beta particles. The amount and duration of exposure to ionizing radiation are important factors in determining the potential health effects, which can range from mild skin irritation to an increased risk of cancer and other diseases.

Homologous recombination is a type of genetic recombination that occurs between two similar or identical (homologous) segments of DNA. It is a natural process that helps to maintain the stability of an organism's genome and plays a crucial role in DNA repair, particularly the repair of double-strand breaks.

In homologous recombination, the two DNA molecules exchange genetic information through a series of steps, including the formation of Holliday junctions, where the strands cross over and exchange partners. This process can result in new combinations of genetic material, which can increase genetic diversity and contribute to evolution.

Homologous recombination is also used in biotechnology and genetic engineering to introduce specific changes into DNA sequences or to create genetically modified organisms.

DNA replication is the biological process by which DNA makes an identical copy of itself during cell division. It is a fundamental mechanism that allows genetic information to be passed down from one generation of cells to the next. During DNA replication, each strand of the double helix serves as a template for the synthesis of a new complementary strand. This results in the creation of two identical DNA molecules. The enzymes responsible for DNA replication include helicase, which unwinds the double helix, and polymerase, which adds nucleotides to the growing strands.

Teniposide is a synthetic podophyllotoxin derivative, which is an antineoplastic agent. It works by interfering with the DNA synthesis and function of cancer cells, leading to cell cycle arrest and apoptosis (programmed cell death). Teniposide is primarily used in the treatment of acute lymphoblastic leukemia (ALL) and other malignancies in children. It is often administered through intravenous infusion and is typically used in combination with other chemotherapeutic agents.

The medical definition of Teniposide can be stated as:

Teniposide, chemically known as (4'-demethylepipodophyllotoxin 9-[4,6-O-(R)-benzylidene-α-L-glucopyranoside]), is a semi-synthetic podophyllotoxin derivative with antineoplastic activity. It inhibits DNA topoisomerase II, leading to the formation of DNA-topoisomerase II cleavable complexes, G2 arrest, and apoptosis in cancer cells. Teniposide is primarily used in the treatment of acute lymphoblastic leukemia (ALL) and other malignancies in children, often administered through intravenous infusion and typically used in combination with other chemotherapeutic agents.

Fungal DNA refers to the genetic material present in fungi, which are a group of eukaryotic organisms that include microorganisms such as yeasts and molds, as well as larger organisms like mushrooms. The DNA of fungi, like that of all living organisms, is made up of nucleotides that are arranged in a double helix structure.

Fungal DNA contains the genetic information necessary for the growth, development, and reproduction of fungi. This includes the instructions for making proteins, which are essential for the structure and function of cells, as well as other important molecules such as enzymes and nucleic acids.

Studying fungal DNA can provide valuable insights into the biology and evolution of fungi, as well as their potential uses in medicine, agriculture, and industry. For example, researchers have used genetic engineering techniques to modify the DNA of fungi to produce drugs, biofuels, and other useful products. Additionally, understanding the genetic makeup of pathogenic fungi can help scientists develop new strategies for preventing and treating fungal infections.

Nuclear proteins are a category of proteins that are primarily found in the nucleus of a eukaryotic cell. They play crucial roles in various nuclear functions, such as DNA replication, transcription, repair, and RNA processing. This group includes structural proteins like lamins, which form the nuclear lamina, and regulatory proteins, such as histones and transcription factors, that are involved in gene expression. Nuclear localization signals (NLS) often help target these proteins to the nucleus by interacting with importin proteins during active transport across the nuclear membrane.

Protein-Serine-Threonine Kinases (PSTKs) are a type of protein kinase that catalyzes the transfer of a phosphate group from ATP to the hydroxyl side chains of serine or threonine residues on target proteins. This phosphorylation process plays a crucial role in various cellular signaling pathways, including regulation of metabolism, gene expression, cell cycle progression, and apoptosis. PSTKs are involved in many physiological and pathological processes, and their dysregulation has been implicated in several diseases, such as cancer, diabetes, and neurodegenerative disorders.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Endonucleases are enzymes that cleave, or cut, phosphodiester bonds within a polynucleotide chain, specifically within the same molecule of DNA or RNA. They can be found in all living organisms and play crucial roles in various biological processes, such as DNA replication, repair, and recombination.

Endonucleases can recognize specific nucleotide sequences (sequence-specific endonucleases) or have no sequence preference (non-specific endonucleases). Some endonucleases generate sticky ends, overhangs of single-stranded DNA after cleavage, while others produce blunt ends without any overhang.

These enzymes are widely used in molecular biology techniques, such as restriction digestion, cloning, and genome editing (e.g., CRISPR-Cas9 system). Restriction endonucleases recognize specific DNA sequences called restriction sites and cleave the phosphodiester bonds at or near these sites, generating defined fragment sizes that can be separated by agarose gel electrophoresis. This property is essential for various applications in genetic engineering and biotechnology.

Saccharomyces cerevisiae proteins are the proteins that are produced by the budding yeast, Saccharomyces cerevisiae. This organism is a single-celled eukaryote that has been widely used as a model organism in scientific research for many years due to its relatively simple genetic makeup and its similarity to higher eukaryotic cells.

The genome of Saccharomyces cerevisiae has been fully sequenced, and it is estimated to contain approximately 6,000 genes that encode proteins. These proteins play a wide variety of roles in the cell, including catalyzing metabolic reactions, regulating gene expression, maintaining the structure of the cell, and responding to environmental stimuli.

Many Saccharomyces cerevisiae proteins have human homologs and are involved in similar biological processes, making this organism a valuable tool for studying human disease. For example, many of the proteins involved in DNA replication, repair, and recombination in yeast have human counterparts that are associated with cancer and other diseases. By studying these proteins in yeast, researchers can gain insights into their function and regulation in humans, which may lead to new treatments for disease.

Cytidine deaminase is an enzyme that catalyzes the removal of an amino group from cytidine, converting it to uridine. This reaction is part of the process of RNA degradation and also plays a role in the immune response to viral infections.

Cytidine deaminase can be found in various organisms, including bacteria, humans, and other mammals. In humans, cytidine deaminase is encoded by the APOBEC3 gene family, which consists of several different enzymes that have distinct functions and expression patterns. Some members of this gene family are involved in the restriction of retroviruses, such as HIV-1, while others play a role in the regulation of endogenous retroelements and the modification of cellular RNA.

Mutations in cytidine deaminase genes have been associated with various diseases, including cancer and autoimmune disorders. For example, mutations in the APOBEC3B gene have been linked to an increased risk of breast cancer, while mutations in other members of the APOBEC3 family have been implicated in the development of lymphoma and other malignancies. Additionally, aberrant expression of cytidine deaminase enzymes has been observed in some autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus, suggesting a potential role for these enzymes in the pathogenesis of these conditions.

"Saccharomyces cerevisiae" is not typically considered a medical term, but it is a scientific name used in the field of microbiology. It refers to a species of yeast that is commonly used in various industrial processes, such as baking and brewing. It's also widely used in scientific research due to its genetic tractability and eukaryotic cellular organization.

However, it does have some relevance to medical fields like medicine and nutrition. For example, certain strains of S. cerevisiae are used as probiotics, which can provide health benefits when consumed. They may help support gut health, enhance the immune system, and even assist in the digestion of certain nutrients.

In summary, "Saccharomyces cerevisiae" is a species of yeast with various industrial and potential medical applications.

Topoisomerase I inhibitors are a class of anticancer drugs that work by inhibiting the function of topoisomerase I, an enzyme that plays a crucial role in the relaxation and replication of DNA. By inhibiting this enzyme's activity, these drugs interfere with the normal unwinding and separation of DNA strands, leading to DNA damage and ultimately cell death. Topoisomerase I inhibitors are used in the treatment of various types of cancer, including colon, small cell lung, ovarian, and cervical cancers. Examples of topoisomerase I inhibitors include camptothecin, irinotecan, and topotecan.

A telomere is a region of repetitive DNA sequences found at the end of chromosomes, which protects the genetic data from damage and degradation during cell division. Telomeres naturally shorten as cells divide, and when they become too short, the cell can no longer divide and becomes senescent or dies. This natural process is associated with aging and various age-related diseases. The length of telomeres can also be influenced by various genetic and environmental factors, including stress, diet, and lifestyle.

DNA topoisomerases are enzymes that modify the topological structure of DNA by regulating the number of twists or supercoils in the double helix. There are two main types of DNA topoisomerases: type I and type II.

Type I DNA topoisomerases function by cutting one strand of the DNA duplex, allowing the uncut strand to rotate around the break, and then resealing the break. This process can relieve both positive and negative supercoiling in DNA, as well as introduce single-stranded breaks into the DNA molecule.

Type I topoisomerases are further divided into three subtypes: type IA, type IB, and type IC. These subtypes differ in their mechanism of action and the structure of the active site tyrosine residue that makes the transient break in the DNA strand.

Overall, DNA topoisomerases play a crucial role in many cellular processes involving DNA, including replication, transcription, recombination, and chromosome segregation. Dysregulation of these enzymes has been implicated in various human diseases, including cancer and genetic disorders.

Tumor suppressor proteins are a type of regulatory protein that helps control the cell cycle and prevent cells from dividing and growing in an uncontrolled manner. They work to inhibit tumor growth by preventing the formation of tumors or slowing down their progression. These proteins can repair damaged DNA, regulate gene expression, and initiate programmed cell death (apoptosis) if the damage is too severe for repair.

Mutations in tumor suppressor genes, which provide the code for these proteins, can lead to a decrease or loss of function in the resulting protein. This can result in uncontrolled cell growth and division, leading to the formation of tumors and cancer. Examples of tumor suppressor proteins include p53, Rb (retinoblastoma), and BRCA1/2.

Chromatin is the complex of DNA, RNA, and proteins that make up the chromosomes in the nucleus of a cell. It is responsible for packaging the long DNA molecules into a more compact form that fits within the nucleus. Chromatin is made up of repeating units called nucleosomes, which consist of a histone protein octamer wrapped tightly by DNA. The structure of chromatin can be altered through chemical modifications to the histone proteins and DNA, which can influence gene expression and other cellular processes.

Chromosomes in fungi are thread-like structures that contain genetic material, composed of DNA and proteins, present in the nucleus of a cell. Unlike humans and other eukaryotes that have a diploid number of chromosomes in their somatic cells, fungal chromosome numbers can vary widely between and within species.

Fungal chromosomes are typically smaller and fewer in number compared to those found in plants and animals. The chromosomal organization in fungi is also different from other eukaryotes. In many fungi, the chromosomes are condensed throughout the cell cycle, whereas in other eukaryotes, chromosomes are only condensed during cell division.

Fungi can have linear or circular chromosomes, depending on the species. For example, the model organism Saccharomyces cerevisiae (budding yeast) has a set of 16 small circular chromosomes, while other fungi like Neurospora crassa (red bread mold) and Aspergillus nidulans (a filamentous fungus) have linear chromosomes.

Fungal chromosomes play an essential role in the growth, development, reproduction, and survival of fungi. They carry genetic information that determines various traits such as morphology, metabolism, pathogenicity, and resistance to environmental stresses. Advances in genomic technologies have facilitated the study of fungal chromosomes, leading to a better understanding of their structure, function, and evolution.

According to the medical definition, ultraviolet (UV) rays are invisible radiations that fall in the range of the electromagnetic spectrum between 100-400 nanometers. UV rays are further divided into three categories: UVA (320-400 nm), UVB (280-320 nm), and UVC (100-280 nm).

UV rays have various sources, including the sun and artificial sources like tanning beds. Prolonged exposure to UV rays can cause damage to the skin, leading to premature aging, eye damage, and an increased risk of skin cancer. UVA rays penetrate deeper into the skin and are associated with skin aging, while UVB rays primarily affect the outer layer of the skin and are linked to sunburns and skin cancer. UVC rays are the most harmful but fortunately, they are absorbed by the Earth's atmosphere and do not reach the surface.

Healthcare professionals recommend limiting exposure to UV rays, wearing protective clothing, using broad-spectrum sunscreen with an SPF of at least 30, and avoiding tanning beds to reduce the risk of UV-related health problems.

The cell cycle is a series of events that take place in a cell leading to its division and duplication. It consists of four main phases: G1 phase, S phase, G2 phase, and M phase.

During the G1 phase, the cell grows in size and synthesizes mRNA and proteins in preparation for DNA replication. In the S phase, the cell's DNA is copied, resulting in two complete sets of chromosomes. During the G2 phase, the cell continues to grow and produces more proteins and organelles necessary for cell division.

The M phase is the final stage of the cell cycle and consists of mitosis (nuclear division) and cytokinesis (cytoplasmic division). Mitosis results in two genetically identical daughter nuclei, while cytokinesis divides the cytoplasm and creates two separate daughter cells.

The cell cycle is regulated by various checkpoints that ensure the proper completion of each phase before progressing to the next. These checkpoints help prevent errors in DNA replication and division, which can lead to mutations and cancer.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

Checkpoint Kinase 2 (Chk2) is a serine/threonine protein kinase that plays a crucial role in the DNA damage response and the regulation of the cell cycle. It is activated by various types of DNA damage, including double-strand breaks, and phosphorylates several downstream targets involved in cell cycle arrest, DNA repair, and apoptosis. Chk2 is a key player in the G2/M checkpoint, which prevents cells with damaged DNA from entering mitosis and dividing. Mutations in the Chk2 gene have been associated with increased risk of cancer.

Ethacridine is an antiseptic and disinfectant agent that was previously used in medical and veterinary settings. It is a synthetic compound with the chemical formula C~14~H~15~ClN~3~O. Ethacridine has been used as a topical treatment for wounds, burns, and skin infections due to its ability to kill bacteria, fungi, and viruses. However, its use has declined over the years due to concerns about its potential toxicity and side effects.

Ethacridine works by interfering with the metabolic processes of microorganisms, which ultimately leads to their death. It is particularly effective against gram-negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa. However, it has limited activity against gram-positive bacteria, such as Staphylococcus aureus.

Despite its antimicrobial properties, ethacridine is not commonly used in clinical practice today due to its potential toxicity. It can cause skin irritation, allergic reactions, and damage to the eyes and mucous membranes. Additionally, there are concerns that ethacridine may be absorbed into the body and cause harm to internal organs, such as the liver and kidneys.

Overall, while ethacridine has been a useful antiseptic and disinfectant in the past, its use is now limited due to concerns about its safety and efficacy.

A dose-response relationship in radiation refers to the correlation between the amount of radiation exposure (dose) and the biological response or adverse health effects observed in exposed individuals. As the level of radiation dose increases, the severity and frequency of the adverse health effects also tend to increase. This relationship is crucial in understanding the risks associated with various levels of radiation exposure and helps inform radiation protection standards and guidelines.

The effects of ionizing radiation can be categorized into two types: deterministic and stochastic. Deterministic effects have a threshold dose below which no effect is observed, and above this threshold, the severity of the effect increases with higher doses. Examples include radiation-induced cataracts or radiation dermatitis. Stochastic effects, on the other hand, do not have a clear threshold and are based on probability; as the dose increases, so does the likelihood of the adverse health effect occurring, such as an increased risk of cancer.

Understanding the dose-response relationship in radiation exposure is essential for setting limits on occupational and public exposure to ionizing radiation, optimizing radiation protection practices, and developing effective medical countermeasures in case of radiation emergencies.

Cell survival refers to the ability of a cell to continue living and functioning normally, despite being exposed to potentially harmful conditions or treatments. This can include exposure to toxins, radiation, chemotherapeutic drugs, or other stressors that can damage cells or interfere with their normal processes.

In scientific research, measures of cell survival are often used to evaluate the effectiveness of various therapies or treatments. For example, researchers may expose cells to a particular drug or treatment and then measure the percentage of cells that survive to assess its potential therapeutic value. Similarly, in toxicology studies, measures of cell survival can help to determine the safety of various chemicals or substances.

It's important to note that cell survival is not the same as cell proliferation, which refers to the ability of cells to divide and multiply. While some treatments may promote cell survival, they may also inhibit cell proliferation, making them useful for treating diseases such as cancer. Conversely, other treatments may be designed to specifically target and kill cancer cells, even if it means sacrificing some healthy cells in the process.

Rad52 is a DNA repair and recombination protein that plays a crucial role in the maintenance of genomic stability in cells. It is highly conserved across various species, including yeast, humans, and other mammals. The primary function of Rad52 is to facilitate the process of homologous recombination (HR), which is a critical DNA repair mechanism that helps to maintain the integrity of the genetic material in the event of double-strand breaks (DSBs) or other types of DNA damage.

Rad52 has several essential roles in HR:

1. Rad52 promotes the formation of ssDNA-Rad51 nucleoprotein filaments: Rad52 interacts with single-stranded DNA (ssDNA) generated during resection of DSBs, facilitating the recruitment and loading of the Rad51 recombinase onto the ssDNA. This Rad51-ssDNA nucleoprotein filament formation is a key step in HR, as it enables the search for homologous sequences and subsequent strand invasion.

2. Rad52 mediates DNA annealing: Rad52 can catalyze the annealing of complementary ssDNA molecules, promoting the reannealing of invaded strands during HR or facilitating the pairing of RPA-coated ssDNA with homologous duplex DNA.

3. Rad52 stimulates D-loop formation and extension: Rad52 can stimulate the extension of D-loops, which are three-stranded structures formed when a single-stranded DNA invades a double-stranded DNA molecule during HR. This process is essential for the subsequent steps of homology search and strand exchange.

4. Rad52 facilitates RPA displacement: Rad52 can displace replication protein A (RPA) from ssDNA, allowing Rad51 to bind and form nucleoprotein filaments. This is a critical step in HR, as RPA inhibits Rad51 binding to ssDNA.

5. Rad52 interacts with other DNA repair proteins: Rad52 interacts with various DNA repair proteins, including BRCA1, BRCA2, and the single-strand binding protein RPA, to coordinate HR and other DNA repair pathways.

In summary, Rad52 is a crucial player in homologous recombination (HR) and DNA damage response. It functions as a mediator of DNA annealing, D-loop formation, and RPA displacement, promoting efficient HR and maintaining genome stability.

Deoxyribonucleases, Type II Site-Specific are a type of enzymes that cleave phosphodiester bonds in DNA molecules at specific recognition sites. They are called "site-specific" because they cut DNA at particular sequences, rather than at random or nonspecific locations. These enzymes belong to the class of endonucleases and play crucial roles in various biological processes such as DNA recombination, repair, and restriction.

Type II deoxyribonucleases are further classified into several subtypes based on their cofactor requirements, recognition site sequences, and cleavage patterns. The most well-known examples of Type II deoxyribonucleases are the restriction endonucleases, which recognize specific DNA motifs in double-stranded DNA and cleave them, generating sticky ends or blunt ends. These enzymes are widely used in molecular biology research for various applications such as genetic engineering, cloning, and genome analysis.

It is important to note that the term "Deoxyribonucleases, Type II Site-Specific" refers to a broad category of enzymes with similar properties and functions, rather than a specific enzyme or family of enzymes. Therefore, providing a concise medical definition for this term can be challenging, as it covers a wide range of enzymes with distinct characteristics and applications.

Enediynes are a class of organic compounds that contain an unsaturated hydrocarbon structure consisting of two double bonds separated by a single bond, forming a core structural unit of R-C=C=C=C-R'. This unique arrangement gives enediynes significant chemical reactivity and has been the basis for their development as antitumor agents.

Enediynes can undergo a cyclization reaction known as the Bergman cyclization, which generates a highly reactive 1,4-diradical species capable of causing significant damage to DNA and other cellular components. This property has been exploited in the design of enediyne-based anticancer drugs, such as neocarzinostatin and calicheamicin, that can selectively target and destroy cancer cells while minimizing harm to normal tissues.

It is important to note that this definition is a general description of the chemical structure and properties of enediynes, and it does not provide specific medical advice or recommendations for treatment. If you have any questions about enediynes or their potential use in medicine, please consult with a qualified healthcare professional.

Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive disorder characterized by extreme sensitivity to ionizing radiation, progressive microcephaly, short stature, immunodeficiency, and an increased risk of developing malignancies, particularly lymphoid tumors. The syndrome is caused by mutations in the NBN gene, which encodes a protein called nibrin that plays a critical role in DNA repair and maintenance of genomic stability.

Individuals with NBS typically have microcephaly at birth or develop it in early childhood, accompanied by developmental delay, intellectual disability, and characteristic facial features such as a prominent forehead, recessed jaw, and widely spaced eyes. They may also have skin abnormalities, skeletal anomalies, and hearing loss.

Immunodeficiency is a common feature of NBS, with patients often experiencing recurrent infections due to impaired immune function. They may have low levels of immunoglobulins and T-cell lymphopenia, which can increase their susceptibility to infections.

NBS is associated with an increased risk of malignancies, particularly lymphoid tumors such as B-cell non-Hodgkin lymphoma and leukemia. The risk of cancer increases with age, and most patients develop a malignancy by their mid-20s.

The diagnosis of NBS is typically made based on clinical features, genetic testing, and confirmation of biallelic mutations in the NBN gene. Treatment may involve management of infections, immunoglobulin replacement therapy, and chemotherapy or radiation therapy for malignancies. However, these treatments can be challenging due to the increased sensitivity to ionizing radiation and potential toxicity of chemotherapeutic agents.

Overall, NBS is a rare but serious disorder that requires multidisciplinary care from specialists in genetics, immunology, oncology, and other fields.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

Genetic models are theoretical frameworks used in genetics to describe and explain the inheritance patterns and genetic architecture of traits, diseases, or phenomena. These models are based on mathematical equations and statistical methods that incorporate information about gene frequencies, modes of inheritance, and the effects of environmental factors. They can be used to predict the probability of certain genetic outcomes, to understand the genetic basis of complex traits, and to inform medical management and treatment decisions.

There are several types of genetic models, including:

1. Mendelian models: These models describe the inheritance patterns of simple genetic traits that follow Mendel's laws of segregation and independent assortment. Examples include autosomal dominant, autosomal recessive, and X-linked inheritance.
2. Complex trait models: These models describe the inheritance patterns of complex traits that are influenced by multiple genes and environmental factors. Examples include heart disease, diabetes, and cancer.
3. Population genetics models: These models describe the distribution and frequency of genetic variants within populations over time. They can be used to study evolutionary processes, such as natural selection and genetic drift.
4. Quantitative genetics models: These models describe the relationship between genetic variation and phenotypic variation in continuous traits, such as height or IQ. They can be used to estimate heritability and to identify quantitative trait loci (QTLs) that contribute to trait variation.
5. Statistical genetics models: These models use statistical methods to analyze genetic data and infer the presence of genetic associations or linkage. They can be used to identify genetic risk factors for diseases or traits.

Overall, genetic models are essential tools in genetics research and medical genetics, as they allow researchers to make predictions about genetic outcomes, test hypotheses about the genetic basis of traits and diseases, and develop strategies for prevention, diagnosis, and treatment.

Exodeoxyribonuclease V, also known as RecJ or ExoV, is an enzyme that belongs to the family of exodeoxyribonucleases. It functions by removing nucleotides from the 3'-end of a DNA strand in a stepwise manner, leaving 5'-phosphate and 3'-hydroxyl groups after each cleavage event. Exodeoxyribonuclease V plays a crucial role in various DNA metabolic processes, including DNA repair, recombination, and replication. It is highly specific for double-stranded DNA substrates and requires the presence of a 5'-phosphate group at the cleavage site. Exodeoxyribonuclease V has been identified in several organisms, including bacteria and archaea, and its activity is tightly regulated to ensure proper maintenance and protection of genomic integrity.

DNA-activated protein kinase (DNA-PK) is a type of serine/threonine protein kinase that plays a crucial role in the DNA damage response and repair processes in cells. It is composed of a catalytic subunit, DNA-PKcs, and a regulatory subunit, Ku, which binds to double-stranded DNA breaks and recruits DNA-PKcs to the site of damage.

Once activated by DNA damage, DNA-PK phosphorylates various downstream targets involved in DNA repair, including proteins involved in non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ is a major pathway for the repair of double-stranded DNA breaks, while HR is a more accurate but slower process that requires a template for repair.

Dysregulation of DNA-PK has been implicated in various human diseases, including cancer and neurological disorders. Inhibitors of DNA-PK are being investigated as potential therapeutic agents for the treatment of cancer, particularly in combination with other DNA damage response inhibitors or radiation therapy.

"Cruciform DNA" is a term used to describe a specific conformation or structure that a double-stranded DNA molecule can adopt. It is so-called because the structure resembles the shape of a cross or crucifix.

This conformation arises when two inverted repeats of DNA sequence are located close to each other on the same DNA molecule, such that they can pair up and form a stable secondary structure. This results in the formation of a hairpin loop at each end of the inverted repeat sequences, with the loops pointing towards each other and the intervening sequences forming two arms that cross in the middle.

Cruciform structures are important in various biological processes, including DNA replication, repair, and recombination. However, they can also pose challenges to these processes, as the crossing of the DNA strands can create topological constraints that must be resolved before replication or transcription can proceed.

It's worth noting that cruciform structures are not stable in solution and are usually only observed under specific conditions, such as when the DNA is supercoiled or when negative supercoiling is introduced through the action of enzymes like topoisomerases.

RecQ helicases are a group of enzymes that belong to the RecQ family, which are named after the E. coli RecQ protein. These helicases play crucial roles in maintaining genomic stability by participating in various DNA metabolic processes such as DNA replication, repair, recombination, and transcription. They are highly conserved across different species, including bacteria, yeast, plants, and mammals.

In humans, there are five RecQ helicases: RECQL1, RECQL4, RECQL5, BLM (RecQ-like helicase), and WRN (Werner syndrome ATP-dependent helicase). Defects in these proteins have been linked to various genetic disorders. For instance, mutations in the BLM gene cause Bloom's syndrome, while mutations in the WRN gene lead to Werner syndrome, both of which are characterized by genomic instability and increased cancer predisposition.

RecQ helicases possess 3'-5' DNA helicase activity, unwinding double-stranded DNA into single strands, and can also perform other functions like branch migration, strand annealing, and removal of protein-DNA crosslinks. Their roles in DNA metabolism help prevent and resolve DNA damage, maintain proper chromosome segregation during cell division, and ensure the integrity of the genome.

Chromosome aberrations refer to structural and numerical changes in the chromosomes that can occur spontaneously or as a result of exposure to mutagenic agents. These changes can affect the genetic material encoded in the chromosomes, leading to various consequences such as developmental abnormalities, cancer, or infertility.

Structural aberrations include deletions, duplications, inversions, translocations, and rings, which result from breaks and rearrangements of chromosome segments. Numerical aberrations involve changes in the number of chromosomes, such as aneuploidy (extra or missing chromosomes) or polyploidy (multiples of a complete set of chromosomes).

Chromosome aberrations can be detected and analyzed using various cytogenetic techniques, including karyotyping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). These methods allow for the identification and characterization of chromosomal changes at the molecular level, providing valuable information for genetic counseling, diagnosis, and research.

Gene conversion is a process in genetics that involves the non-reciprocal transfer of genetic information from one region of a chromosome to a corresponding region on its homologous chromosome. This process results in a segment of DNA on one chromosome being replaced with a corresponding segment from the other chromosome, leading to a change in the genetic sequence and potentially the phenotype.

Gene conversion can occur during meiosis, as a result of homologous recombination between two similar or identical sequences. It is a natural process that helps maintain genetic diversity within populations and can also play a role in the evolution of genes and genomes. However, gene conversion can also lead to genetic disorders if it occurs in an important gene and results in a deleterious mutation.

Methyl methanesulfonate (MMS) is not a medication, but rather a chemical compound with the formula CH3SO3CH3. It's an alkylating agent that is used in laboratory settings for various research purposes, including as a methylating agent in biochemical and genetic studies.

MMS works by transferring its methyl group (CH3) to other molecules, which can result in the modification of DNA and other biological macromolecules. This property makes it useful in laboratory research, but it also means that MMS is highly reactive and toxic. Therefore, it must be handled with care and appropriate safety precautions.

It's important to note that MMS is not used as a therapeutic agent in medicine due to its high toxicity and potential to cause serious harm if mishandled or misused.

Phleomycins are a group of antibiotics produced by the fungus Streptomyces verticillus. They are known for their ability to bind to DNA and cause breaks in the double helix, which makes them useful as antitumor agents. Phleomycin D1, also known as bleomycin, is a member of this family that is commonly used in cancer chemotherapy. It can cause damage to both cancerous and normal cells, but its therapeutic effect is due to its greater toxicity towards cancer cells. The main side effects of phleomycins include lung fibrosis, hair loss, and a decrease in the number of white blood cells.

Etoposide is a chemotherapy medication used to treat various types of cancer, including lung cancer, testicular cancer, and certain types of leukemia. It works by inhibiting the activity of an enzyme called topoisomerase II, which is involved in DNA replication and transcription. By doing so, etoposide can interfere with the growth and multiplication of cancer cells.

Etoposide is often administered intravenously in a hospital or clinic setting, although it may also be given orally in some cases. The medication can cause a range of side effects, including nausea, vomiting, hair loss, and an increased risk of infection. It can also have more serious side effects, such as bone marrow suppression, which can lead to anemia, bleeding, and a weakened immune system.

Like all chemotherapy drugs, etoposide is not without risks and should only be used under the close supervision of a qualified healthcare provider. It is important for patients to discuss the potential benefits and risks of this medication with their doctor before starting treatment.

The cell nucleus is a membrane-bound organelle found in the eukaryotic cells (cells with a true nucleus). It contains most of the cell's genetic material, organized as DNA molecules in complex with proteins, RNA molecules, and histones to form chromosomes.

The primary function of the cell nucleus is to regulate and control the activities of the cell, including growth, metabolism, protein synthesis, and reproduction. It also plays a crucial role in the process of mitosis (cell division) by separating and protecting the genetic material during this process. The nuclear membrane, or nuclear envelope, surrounding the nucleus is composed of two lipid bilayers with numerous pores that allow for the selective transport of molecules between the nucleoplasm (nucleus interior) and the cytoplasm (cell exterior).

The cell nucleus is a vital structure in eukaryotic cells, and its dysfunction can lead to various diseases, including cancer and genetic disorders.

Chromosomal instability is a term used in genetics to describe a type of genetic alteration where there are abnormalities in the number or structure of chromosomes within cells. Chromosomes are thread-like structures that contain our genetic material, and they usually exist in pairs in the nucleus of a cell.

Chromosomal instability can arise due to various factors, including errors in DNA replication or repair, problems during cell division, or exposure to environmental mutagens. This instability can lead to an increased frequency of chromosomal abnormalities, such as deletions, duplications, translocations, or changes in the number of chromosomes.

Chromosomal instability is associated with several human diseases, including cancer. In cancer cells, chromosomal instability can contribute to tumor heterogeneity, drug resistance, and disease progression. It is also observed in certain genetic disorders, such as Down syndrome, where an extra copy of chromosome 21 is present, and in some rare inherited syndromes, such as Bloom syndrome and Fanconi anemia, which are characterized by a high risk of cancer and other health problems.

HeLa cells are a type of immortalized cell line used in scientific research. They are derived from a cancer that developed in the cervical tissue of Henrietta Lacks, an African-American woman, in 1951. After her death, cells taken from her tumor were found to be capable of continuous division and growth in a laboratory setting, making them an invaluable resource for medical research.

HeLa cells have been used in a wide range of scientific studies, including research on cancer, viruses, genetics, and drug development. They were the first human cell line to be successfully cloned and are able to grow rapidly in culture, doubling their population every 20-24 hours. This has made them an essential tool for many areas of biomedical research.

It is important to note that while HeLa cells have been instrumental in numerous scientific breakthroughs, the story of their origin raises ethical questions about informed consent and the use of human tissue in research.

Chromatids are defined as the individual strands that make up a duplicated chromosome. They are formed during the S phase of the cell cycle, when replication occurs and each chromosome is copied, resulting in two identical sister chromatids. These chromatids are connected at a region called the centromere and are held together by cohesin protein complexes until they are separated during mitosis or meiosis.

During mitosis, the sister chromatids are pulled apart by the mitotic spindle apparatus and distributed equally to each daughter cell. In meiosis, which is a type of cell division that occurs in the production of gametes (sex cells), homologous chromosomes pair up and exchange genetic material through a process called crossing over. After crossing over, each homologous chromosome consists of two recombinant chromatids that are separated during meiosis I, and then sister chromatids are separated during meiosis II.

Chromatids play an essential role in the faithful transmission of genetic information from one generation to the next, ensuring that each daughter cell or gamete receives a complete set of chromosomes with intact and functional genes.

Replication Protein A (RPA) is a single-stranded DNA binding protein complex that plays a crucial role in the process of DNA replication, repair, and recombination. In eukaryotic cells, RPA is composed of three subunits: RPA70, RPA32, and RPA14. The primary function of RPA is to coat single-stranded DNA (ssDNA) generated during these processes, protecting it from degradation, preventing the formation of secondary structures, and promoting the recruitment of other proteins involved in DNA metabolism.

RPA binds ssDNA with high affinity and specificity, forming a stable complex that protects the DNA from nucleases, chemical modifications, and other damaging agents. The protein also participates in the regulation of various enzymatic activities, such as helicase loading and activation, end processing, and polymerase processivity.

During DNA replication, RPA is essential for the initiation and elongation phases. It facilitates the assembly of the pre-replicative complex (pre-RC) at origins of replication, aids in the recruitment and activation of helicases, and promotes the switch from MCM2-7 helicase to polymerase processivity during DNA synthesis.

In addition to its role in DNA replication, RPA is involved in various DNA repair pathways, including nucleotide excision repair (NER), base excision repair (BER), mismatch repair (MMR), and double-strand break repair (DSBR). It also plays a critical role in meiotic recombination during sexual reproduction.

In summary, Replication Protein A (RPA) is a eukaryotic single-stranded DNA binding protein complex that protects, stabilizes, and regulates ssDNA during DNA replication, repair, and recombination processes.

Poly(ADP-ribose) (PAR) is not strictly referred to as "Poly Adenosine Diphosphate Ribose" in the medical or biochemical context, although the term ADP-ribose is a component of it. Poly(ADP-ribose) is a polymer of ADP-ribose units that are synthesized by enzymes called poly(ADP-ribose) polymerases (PARPs).

Poly(ADP-ribosyl)ation, the process of adding PAR polymers to target proteins, plays a crucial role in various cellular processes such as DNA repair, genomic stability, and cell death. In medical research, alterations in PAR metabolism have been implicated in several diseases, including cancer and neurodegenerative disorders. Therefore, understanding the function and regulation of poly(ADP-ribose) is of significant interest in biomedical sciences.

Mutagens are physical or chemical agents that can cause permanent changes in the structure of genetic material, including DNA and chromosomes, leading to mutations. These mutations can be passed down to future generations and may increase the risk of cancer and other diseases. Examples of mutagens include ultraviolet (UV) radiation, tobacco smoke, and certain chemicals found in industrial settings. It is important to note that not all mutations are harmful, but some can have negative effects on health and development.

Podophyllotoxin is a pharmaceutical agent derived from the podophyllum plant. It is an antimitotic compound that inhibits microtubule assembly, leading to cell cycle arrest and apoptosis. It is primarily used in topical form as a treatment for genital warts, caused by certain types of human papillomavirus (HPV). Podophyllotoxin works by interfering with the growth of the wart cells, eventually causing them to die off.

It's important to note that podophyllotoxin is a potent cytotoxic agent and should only be used under the supervision of a healthcare professional. It should not be taken orally or applied to open wounds, and it should be kept out of reach of children.

Apoptosis is a programmed and controlled cell death process that occurs in multicellular organisms. It is a natural process that helps maintain tissue homeostasis by eliminating damaged, infected, or unwanted cells. During apoptosis, the cell undergoes a series of morphological changes, including cell shrinkage, chromatin condensation, and fragmentation into membrane-bound vesicles called apoptotic bodies. These bodies are then recognized and engulfed by neighboring cells or phagocytic cells, preventing an inflammatory response. Apoptosis is regulated by a complex network of intracellular signaling pathways that involve proteins such as caspases, Bcl-2 family members, and inhibitors of apoptosis (IAPs).

Bleomycin is a type of chemotherapeutic agent used to treat various types of cancer, including squamous cell carcinoma, testicular cancer, and lymphomas. It works by causing DNA damage in rapidly dividing cells, which can inhibit the growth and proliferation of cancer cells.

Bleomycin is an antibiotic derived from Streptomyces verticillus and is often administered intravenously or intramuscularly. While it can be effective in treating certain types of cancer, it can also have serious side effects, including lung toxicity, which can lead to pulmonary fibrosis and respiratory failure. Therefore, bleomycin should only be used under the close supervision of a healthcare professional who is experienced in administering chemotherapy drugs.

X-rays, also known as radiographs, are a type of electromagnetic radiation with higher energy and shorter wavelength than visible light. In medical imaging, X-rays are used to produce images of the body's internal structures, such as bones and organs, by passing the X-rays through the body and capturing the resulting shadows or patterns on a specialized film or digital detector.

The amount of X-ray radiation used is carefully controlled to minimize exposure and ensure patient safety. Different parts of the body absorb X-rays at different rates, allowing for contrast between soft tissues and denser structures like bone. This property makes X-rays an essential tool in diagnosing and monitoring a wide range of medical conditions, including fractures, tumors, infections, and foreign objects within the body.

VDJ Recombinases are a set of enzymes that play a crucial role in the adaptive immune system, specifically in the diversification of antigen receptors in vertebrates. The name "VDJ" refers to the variable (V), diversity (D), and joining (J) gene segments that undergo recombination to generate a vast array of unique antigen receptor genes.

The VDJ Recombinases are composed of two main enzymatic components: RAG1 and RAG2, which are responsible for initiating the recombination process, and Artemis, which is involved in the cleavage and joining of the gene segments. The recombination process mediated by these enzymes occurs during the development of B and T lymphocytes, allowing for the generation of a diverse repertoire of antigen receptors that can recognize and respond to a wide range of pathogens.

The RAG1 and RAG2 proteins recognize specific DNA sequences called recombination signal sequences (RSSs) that flank the V, D, and J gene segments. They introduce double-stranded breaks at the junctions between these gene segments, creating a hairpin structure at one end of each break. The hairpins are then cleaved by Artemis, and the resulting overhangs are joined together by another set of enzymes to form a functional antigen receptor gene.

Overall, VDJ Recombinases play a critical role in the adaptive immune system's ability to generate diverse and specific responses to pathogens, making them an essential component of vertebrate immunity.

Translocation, genetic, refers to a type of chromosomal abnormality in which a segment of a chromosome is transferred from one chromosome to another, resulting in an altered genome. This can occur between two non-homologous chromosomes (non-reciprocal translocation) or between two homologous chromosomes (reciprocal translocation). Genetic translocations can lead to various clinical consequences, depending on the genes involved and the location of the translocation. Some translocations may result in no apparent effects, while others can cause developmental abnormalities, cancer, or other genetic disorders. In some cases, translocations can also increase the risk of having offspring with genetic conditions.

Chromosomal proteins, non-histone, are a diverse group of proteins that are associated with chromatin, the complex of DNA and histone proteins, but do not have the characteristic structure of histones. These proteins play important roles in various nuclear processes such as DNA replication, transcription, repair, recombination, and chromosome condensation and segregation during cell division. They can be broadly classified into several categories based on their functions, including architectural proteins, enzymes, transcription factors, and structural proteins. Examples of non-histone chromosomal proteins include high mobility group (HMG) proteins, poly(ADP-ribose) polymerases (PARPs), and condensins.

"Gene rearrangement" is a process that involves the alteration of the order, orientation, or copy number of genes or gene segments within an organism's genome. This natural mechanism plays a crucial role in generating diversity and specificity in the immune system, particularly in vertebrates.

In the context of the immune system, gene rearrangement occurs during the development of B-cells and T-cells, which are responsible for adaptive immunity. The process involves breaking and rejoining DNA segments that encode antigen recognition sites, resulting in a unique combination of gene segments and creating a vast array of possible antigen receptors.

There are two main types of gene rearrangement:

1. V(D)J recombination: This process occurs in both B-cells and T-cells. It involves the recombination of variable (V), diversity (D), and joining (J) gene segments to form a functional antigen receptor gene. In humans, there are multiple copies of V, D, and J segments for each antigen receptor gene, allowing for a vast number of possible combinations.
2. Class switch recombination: This process occurs only in mature B-cells after antigen exposure. It involves the replacement of the constant (C) region of the immunoglobulin heavy chain gene with another C region, resulting in the production of different isotypes of antibodies (IgG, IgA, or IgE) that have distinct effector functions while maintaining the same antigen specificity.

These processes contribute to the generation of a diverse repertoire of antigen receptors, allowing the immune system to recognize and respond effectively to a wide range of pathogens.

Ellipticines are a class of naturally occurring alkaloids that have been isolated from various plants, including those in the family Apocynaceae. These compounds have been found to exhibit various biological activities, including anti-cancer and anti-microbial properties.

Ellipticines have a unique chemical structure, characterized by a planar, aromatic core with two side chains that contain nitrogen atoms. This structure allows ellipticines to intercalate into DNA, disrupting its normal function and leading to cell death. As a result, ellipticines have been studied as potential anti-cancer agents, particularly for the treatment of drug-resistant cancers.

In addition to their anti-cancer properties, ellipticines have also been found to exhibit antibacterial, antifungal, and antiparasitic activities. However, further research is needed to fully understand the mechanisms behind these effects and to determine the safety and efficacy of ellipticines as therapeutic agents.

Intercalating agents are chemical substances that can be inserted between the stacked bases of DNA, creating a separation or "intercalation" of the base pairs. This property is often exploited in cancer chemotherapy, where intercalating agents like doxorubicin and daunorubicin are used to inhibit the replication and transcription of cancer cells by preventing the normal functioning of their DNA. However, these agents can also have toxic effects on normal cells, particularly those that divide rapidly, such as bone marrow and gut epithelial cells. Therefore, their use must be carefully monitored and balanced against their therapeutic benefits.

A plasmid is a small, circular, double-stranded DNA molecule that is separate from the chromosomal DNA of a bacterium or other organism. Plasmids are typically not essential for the survival of the organism, but they can confer beneficial traits such as antibiotic resistance or the ability to degrade certain types of pollutants.

Plasmids are capable of replicating independently of the chromosomal DNA and can be transferred between bacteria through a process called conjugation. They often contain genes that provide resistance to antibiotics, heavy metals, and other environmental stressors. Plasmids have also been engineered for use in molecular biology as cloning vectors, allowing scientists to replicate and manipulate specific DNA sequences.

Plasmids are important tools in genetic engineering and biotechnology because they can be easily manipulated and transferred between organisms. They have been used to produce vaccines, diagnostic tests, and genetically modified organisms (GMOs) for various applications, including agriculture, medicine, and industry.

Ataxia telangiectasia is a rare, inherited genetic disorder that affects the nervous system, immune system, and overall development. The condition is characterized by progressive difficulty with coordination and balance (ataxia), as well as the development of small, dilated blood vessels (telangiectasias) on the skin and eyes.

The underlying cause of ataxia telangiectasia is a mutation in the ATM gene, which provides instructions for making a protein that plays a critical role in DNA repair and maintaining genetic stability. When this gene is mutated, cells are unable to properly repair damaged DNA, leading to an increased risk of cancer and other health problems.

Individuals with ataxia telangiectasia typically begin to show symptoms during early childhood, with progressive difficulties in coordination and balance, slurred speech, and recurrent respiratory infections due to weakened immune function. Over time, these symptoms can worsen, leading to significant disability and reduced life expectancy.

There is currently no cure for ataxia telangiectasia, and treatment is focused on managing the symptoms and complications of the condition. This may include physical therapy, speech therapy, and medications to help control infections and other health problems.

The term "DNA, neoplasm" is not a standard medical term or concept. DNA refers to deoxyribonucleic acid, which is the genetic material present in the cells of living organisms. A neoplasm, on the other hand, is a tumor or growth of abnormal tissue that can be benign (non-cancerous) or malignant (cancerous).

In some contexts, "DNA, neoplasm" may refer to genetic alterations found in cancer cells. These genetic changes can include mutations, amplifications, deletions, or rearrangements of DNA sequences that contribute to the development and progression of cancer. Identifying these genetic abnormalities can help doctors diagnose and treat certain types of cancer more effectively.

However, it's important to note that "DNA, neoplasm" is not a term that would typically be used in medical reports or research papers without further clarification. If you have any specific questions about DNA changes in cancer cells or neoplasms, I would recommend consulting with a healthcare professional or conducting further research on the topic.

Sister chromatid exchange (SCE) is a type of genetic recombination that takes place between two identical sister chromatids during the DNA repair process in meiosis or mitosis. It results in an exchange of genetic material between the two chromatids, creating a new combination of genes on each chromatid. This event is a normal part of cell division and helps to increase genetic variability within a population. However, an increased rate of SCEs can also be indicative of exposure to certain genotoxic agents or conditions that cause DNA damage.

Phosphorylation is the process of adding a phosphate group (a molecule consisting of one phosphorus atom and four oxygen atoms) to a protein or other organic molecule, which is usually done by enzymes called kinases. This post-translational modification can change the function, localization, or activity of the target molecule, playing a crucial role in various cellular processes such as signal transduction, metabolism, and regulation of gene expression. Phosphorylation is reversible, and the removal of the phosphate group is facilitated by enzymes called phosphatases.

BRCA1 protein is a tumor suppressor protein that plays a crucial role in repairing damaged DNA and maintaining genomic stability. The BRCA1 gene provides instructions for making this protein. Mutations in the BRCA1 gene can lead to impaired function of the BRCA1 protein, significantly increasing the risk of developing breast, ovarian, and other types of cancer.

The BRCA1 protein forms complexes with several other proteins to participate in various cellular processes, such as:

1. DNA damage response and repair: BRCA1 helps recognize and repair double-strand DNA breaks through homologous recombination, a precise error-free repair mechanism.
2. Cell cycle checkpoints: BRCA1 is involved in regulating the G1/S and G2/M cell cycle checkpoints to ensure proper DNA replication and cell division.
3. Transcription regulation: BRCA1 can act as a transcriptional co-regulator, influencing the expression of genes involved in various cellular processes, including DNA repair and cell cycle control.
4. Apoptosis: In cases of severe or irreparable DNA damage, BRCA1 helps trigger programmed cell death (apoptosis) to eliminate potentially cancerous cells.

Individuals with inherited mutations in the BRCA1 gene have a higher risk of developing breast and ovarian cancers compared to the general population. Genetic testing for BRCA1 mutations is available for individuals with a family history of these cancers or those who meet specific clinical criteria. Identifying carriers of BRCA1 mutations allows for enhanced cancer surveillance, risk reduction strategies, and potential targeted therapies.

Deoxyribonucleases (DNases) are a group of enzymes that cleave, or cut, the phosphodiester bonds in the backbone of deoxyribonucleic acid (DNA) molecules. DNases are classified based on their mechanism of action into two main categories: double-stranded DNases and single-stranded DNases.

Double-stranded DNases cleave both strands of the DNA duplex, while single-stranded DNases cleave only one strand. These enzymes play important roles in various biological processes, such as DNA replication, repair, recombination, and degradation. They are also used in research and clinical settings for applications such as DNA fragmentation analysis, DNA sequencing, and treatment of cystic fibrosis.

It's worth noting that there are many different types of DNases with varying specificities and activities, and the medical definition may vary depending on the context.

The G2 phase, also known as the "gap 2 phase," is a stage in the cell cycle that occurs after DNA replication (S phase) and before cell division (mitosis). During this phase, the cell prepares for mitosis by completing the synthesis of proteins and organelles needed for chromosome separation. The cell also checks for any errors or damage to the DNA before entering mitosis. This phase is a critical point in the cell cycle where proper regulation ensures the faithful transmission of genetic information from one generation of cells to the next. If significant DNA damage is detected during G2, the cell may undergo programmed cell death (apoptosis) instead of dividing.

Chromosome pairing, also known as chromosome synapsis, is a process that occurs during meiosis, which is the type of cell division that results in the formation of sex cells or gametes (sperm and eggs).

In humans, each cell contains 23 pairs of chromosomes, for a total of 46 chromosomes. Of these, 22 pairs are called autosomal chromosomes, and they are similar in size and shape between the two copies in a pair. The last pair is called the sex chromosomes (X and Y), which determine the individual's biological sex.

During meiosis, homologous chromosomes (one from each parent) come together and pair up along their lengths in a process called synapsis. This pairing allows for the precise alignment of corresponding genes and genetic regions between the two homologous chromosomes. Once paired, the chromosomes exchange genetic material through a process called crossing over, which increases genetic diversity in the resulting gametes.

After crossing over, the homologous chromosomes separate during meiosis I, followed by the separation of sister chromatids (the two copies of each chromosome) during meiosis II. The end result is four haploid cells, each containing 23 chromosomes, which then develop into sperm or eggs.

Chromosome pairing is a crucial step in the process of sexual reproduction, ensuring that genetic information is accurately passed from one generation to the next while also promoting genetic diversity through recombination and independent assortment of chromosomes.

Tumor suppressor protein p53, also known as p53 or tumor protein p53, is a nuclear phosphoprotein that plays a crucial role in preventing cancer development and maintaining genomic stability. It does so by regulating the cell cycle and acting as a transcription factor for various genes involved in apoptosis (programmed cell death), DNA repair, and cell senescence (permanent cell growth arrest).

In response to cellular stress, such as DNA damage or oncogene activation, p53 becomes activated and accumulates in the nucleus. Activated p53 can then bind to specific DNA sequences and promote the transcription of target genes that help prevent the proliferation of potentially cancerous cells. These targets include genes involved in cell cycle arrest (e.g., CDKN1A/p21), apoptosis (e.g., BAX, PUMA), and DNA repair (e.g., GADD45).

Mutations in the TP53 gene, which encodes p53, are among the most common genetic alterations found in human cancers. These mutations often lead to a loss or reduction of p53's tumor suppressive functions, allowing cancer cells to proliferate uncontrollably and evade apoptosis. As a result, p53 has been referred to as "the guardian of the genome" due to its essential role in preventing tumorigenesis.

Fibroblasts are specialized cells that play a critical role in the body's immune response and wound healing process. They are responsible for producing and maintaining the extracellular matrix (ECM), which is the non-cellular component present within all tissues and organs, providing structural support and biochemical signals for surrounding cells.

Fibroblasts produce various ECM proteins such as collagens, elastin, fibronectin, and laminins, forming a complex network of fibers that give tissues their strength and flexibility. They also help in the regulation of tissue homeostasis by controlling the turnover of ECM components through the process of remodeling.

In response to injury or infection, fibroblasts become activated and start to proliferate rapidly, migrating towards the site of damage. Here, they participate in the inflammatory response, releasing cytokines and chemokines that attract immune cells to the area. Additionally, they deposit new ECM components to help repair the damaged tissue and restore its functionality.

Dysregulation of fibroblast activity has been implicated in several pathological conditions, including fibrosis (excessive scarring), cancer (where they can contribute to tumor growth and progression), and autoimmune diseases (such as rheumatoid arthritis).

A cell line that is derived from tumor cells and has been adapted to grow in culture. These cell lines are often used in research to study the characteristics of cancer cells, including their growth patterns, genetic changes, and responses to various treatments. They can be established from many different types of tumors, such as carcinomas, sarcomas, and leukemias. Once established, these cell lines can be grown and maintained indefinitely in the laboratory, allowing researchers to conduct experiments and studies that would not be feasible using primary tumor cells. It is important to note that tumor cell lines may not always accurately represent the behavior of the original tumor, as they can undergo genetic changes during their time in culture.

Camptothecin is a topoisomerase I inhibitor, which is a type of chemotherapeutic agent used in cancer treatment. It works by interfering with the function of an enzyme called topoisomerase I, which helps to uncoil DNA during cell division. By inhibiting this enzyme, camptothecin prevents the cancer cells from dividing and growing, ultimately leading to their death.

Camptothecin is found naturally in the bark and stem of the Camptotheca acuminata tree, also known as the "happy tree," which is native to China. It was first isolated in 1966 and has since been developed into several synthetic derivatives, including irinotecan and topotecan, which are used clinically to treat various types of cancer, such as colon, lung, and ovarian cancers.

Like other chemotherapeutic agents, camptothecin can have significant side effects, including nausea, vomiting, diarrhea, and myelosuppression (suppression of bone marrow function). It is important for patients receiving camptothecin-based therapies to be closely monitored by their healthcare team to manage these side effects effectively.

Leukemia L1210 is not a medical definition itself, but it refers to a specific mouse leukemia cell line that was established in 1948. These cells are a type of acute myeloid leukemia (AML) and have been widely used in cancer research as a model for studying the disease, testing new therapies, and understanding the biology of leukemia. The L1210 cell line has contributed significantly to the development of various chemotherapeutic agents and treatment strategies for leukemia and other cancers.

Aphidicolin is an antimicrotubule agent that is specifically a inhibitor of DNA polymerase alpha. It is an antibiotic that is produced by the fungus Cephalosporium aphidicola and is used in research to study the cell cycle and DNA replication. In clinical medicine, it has been explored as a potential anticancer agent, although its use is not currently approved for this indication.

DNA fragmentation is the breaking of DNA strands into smaller pieces. This process can occur naturally during apoptosis, or programmed cell death, where the DNA is broken down and packaged into apoptotic bodies to be safely eliminated from the body. However, excessive or abnormal DNA fragmentation can also occur due to various factors such as oxidative stress, exposure to genotoxic agents, or certain medical conditions. This can lead to genetic instability, cellular dysfunction, and increased risk of diseases such as cancer. In the context of reproductive medicine, high levels of DNA fragmentation in sperm cells have been linked to male infertility and poor assisted reproductive technology outcomes.

Mitosis is a type of cell division in which the genetic material of a single cell, called the mother cell, is equally distributed into two identical daughter cells. It's a fundamental process that occurs in multicellular organisms for growth, maintenance, and repair, as well as in unicellular organisms for reproduction.

The process of mitosis can be broken down into several stages: prophase, prometaphase, metaphase, anaphase, and telophase. During prophase, the chromosomes condense and become visible, and the nuclear envelope breaks down. In prometaphase, the nuclear membrane is completely disassembled, and the mitotic spindle fibers attach to the chromosomes at their centromeres.

During metaphase, the chromosomes align at the metaphase plate, an imaginary line equidistant from the two spindle poles. In anaphase, sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell. Finally, in telophase, new nuclear envelopes form around each set of chromosomes, and the chromosomes decondense and become less visible.

Mitosis is followed by cytokinesis, a process that divides the cytoplasm of the mother cell into two separate daughter cells. The result of mitosis and cytokinesis is two genetically identical cells, each with the same number and kind of chromosomes as the original parent cell.

Cricetinae is a subfamily of rodents that includes hamsters, gerbils, and relatives. These small mammals are characterized by having short limbs, compact bodies, and cheek pouches for storing food. They are native to various parts of the world, particularly in Europe, Asia, and Africa. Some species are popular pets due to their small size, easy care, and friendly nature. In a medical context, understanding the biology and behavior of Cricetinae species can be important for individuals who keep them as pets or for researchers studying their physiology.

Chromosomes are thread-like structures that exist in the nucleus of cells, carrying genetic information in the form of genes. They are composed of DNA and proteins, and are typically present in pairs in the nucleus, with one set inherited from each parent. In humans, there are 23 pairs of chromosomes for a total of 46 chromosomes. Chromosomes come in different shapes and forms, including sex chromosomes (X and Y) that determine the biological sex of an individual. Changes or abnormalities in the number or structure of chromosomes can lead to genetic disorders and diseases.

In the context of cell biology, "S phase" refers to the part of the cell cycle during which DNA replication occurs. The "S" stands for synthesis, reflecting the active DNA synthesis that takes place during this phase. It is preceded by G1 phase (gap 1) and followed by G2 phase (gap 2), with mitosis (M phase) being the final stage of the cell cycle.

During S phase, the cell's DNA content effectively doubles as each chromosome is replicated to ensure that the two resulting daughter cells will have the same genetic material as the parent cell. This process is carefully regulated and coordinated with other events in the cell cycle to maintain genomic stability.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

Bloom syndrome is a rare genetic disorder characterized by short stature, sun-sensitive skin rash, and an increased risk of developing cancer. It is caused by mutations in the BLM gene, which provides instructions for making a protein that helps prevent tangles and knots from forming in DNA during cell division. As a result, cells with Bloom syndrome have a high rate of genetic recombination, leading to chromosomal instability and an increased risk of cancer.

Individuals with Bloom syndrome typically have a distinctive facial appearance, including a narrow face, small jaw, and a prominent nose. They may also have learning disabilities, fertility problems, and an increased susceptibility to infections. The condition is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disorder. Bloom syndrome is typically diagnosed through genetic testing and chromosome analysis. Treatment is focused on managing the symptoms and reducing the risk of cancer through regular screenings and lifestyle modifications.

Protein binding, in the context of medical and biological sciences, refers to the interaction between a protein and another molecule (known as the ligand) that results in a stable complex. This process is often reversible and can be influenced by various factors such as pH, temperature, and concentration of the involved molecules.

In clinical chemistry, protein binding is particularly important when it comes to drugs, as many of them bind to proteins (especially albumin) in the bloodstream. The degree of protein binding can affect a drug's distribution, metabolism, and excretion, which in turn influence its therapeutic effectiveness and potential side effects.

Protein-bound drugs may be less available for interaction with their target tissues, as only the unbound or "free" fraction of the drug is active. Therefore, understanding protein binding can help optimize dosing regimens and minimize adverse reactions.

Recombination is a natural process that occurs in cells to exchange genetic information between two similar or identical strands of DNA. This process helps to maintain the stability and diversity of the genome. RecA (RecA protein) is a type of recombinase enzyme found in bacteria, including Escherichia coli, that plays a crucial role in this process.

RecA recombinases are proteins that facilitate the exchange of genetic information between two DNA molecules by promoting homologous pairing and strand exchange. Homologous pairing is the alignment of similar or identical sequences of nucleotides on two different DNA molecules, while strand exchange refers to the physical transfer of one strand of DNA from one molecule to another.

RecA recombinases work by forming a nucleoprotein filament on single-stranded DNA (ssDNA) and then searching for complementary sequences on double-stranded DNA (dsDNA). Once a complementary sequence is found, the RecA protein facilitates the invasion of the ssDNA into the dsDNA, leading to strand exchange and the formation of a joint molecule. This joint molecule can then be used as a template for DNA replication or repair.

RecA recombinases have been extensively studied due to their importance in genetic recombination and DNA repair. They also have potential applications in biotechnology, such as in the development of genome engineering tools and methods for detecting and quantifying specific DNA sequences.

Telomere-binding proteins are specialized proteins that bind to the telomeres, which are the repetitive DNA sequences found at the ends of chromosomes. These proteins play a crucial role in protecting the structural integrity and stability of chromosomes by preventing the degradation of telomeres during cell division and preventing the chromosomes from being recognized as damaged or broken.

One of the most well-known telomere-binding proteins is called TRF2 (telomeric repeat-binding factor 2), which helps to maintain the structure of the telomere "T-loop" and prevent the activation of DNA repair mechanisms that can lead to chromosomal instability. Another important telomere-binding protein is called POT1 (protection of telomeres 1), which specifically binds to the single-stranded overhang of the telomere and helps to regulate the activity of telomerase, an enzyme that adds DNA repeats to the ends of chromosomes during cell division.

Mutations in telomere-binding proteins have been linked to a variety of human diseases, including premature aging disorders, cancer, and bone marrow failure syndromes. Therefore, understanding the function and regulation of these proteins is an important area of research in molecular biology and genetics.

I apologize for any confusion, but "Schizosaccharomyces" is not a medical term. It is a genus name in the field of microbiology and genetics, referring to a group of budding, tear-shaped yeasts that are widely used as model organisms in scientific research. The most well-known species within this genus is Schizosaccharomyces pombe, which has been extensively studied for its cell cycle regulation, DNA repair mechanisms, and other fundamental biological processes.

If you have any questions related to medical terminology or health-related topics, I would be happy to help.

Chromosome fragile sites are specific locations along the length of a chromosome that are prone to breakage or rearrangement when exposed to certain chemicals or conditions, such as replication stress during cell division. These sites are often characterized by the presence of repetitive DNA sequences and proteins that help maintain the stability of the chromosome.

Fragile sites can be classified into two categories: common and rare. Common fragile sites are present in most individuals and are typically not associated with genetic disorders, while rare fragile sites are less common and may be linked to specific genetic conditions or increased risk for cancer.

When a chromosome breaks at a fragile site, it can lead to various genetic abnormalities such as deletions, duplications, inversions, or translocations of genetic material. These changes can have significant consequences on gene expression and function, potentially leading to developmental disorders, intellectual disability, cancer, or other health issues.

It is important to note that not all fragile sites will result in genetic abnormalities, as some may remain stable under normal conditions. However, certain factors such as environmental exposures, aging, or inherited genetic predispositions can increase the likelihood of chromosomal instability at fragile sites.

A base sequence in the context of molecular biology refers to the specific order of nucleotides in a DNA or RNA molecule. In DNA, these nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, uracil (U) takes the place of thymine. The base sequence contains genetic information that is transcribed into RNA and ultimately translated into proteins. It is the exact order of these bases that determines the genetic code and thus the function of the DNA or RNA molecule.

The Immunoglobulin (Ig) switch region, also known as the switch (S) region or switch area, is a segment of DNA located within the heavy chain constant region (Cμ, Cδ, Cγ, Cε, and Cα) genes of the immunoglobulin locus. These regions are found in chromosome 14 in humans.

The Ig switch regions are crucial for antibody class switching, a process that allows B cells to change the type of heavy chain constant region (Cμ, Cδ, Cγ, Cε, or Cα) expressed in their immunoglobulin, thus modifying the effector functions of the antibodies they produce without altering their antigen specificity. This mechanism enables the immune system to generate a more diverse response against various pathogens and adapt to new challenges.

The switch regions are composed of repetitive DNA sequences that vary in length and sequence between different immunoglobulin isotypes (IgM, IgD, IgG, IgA, and IgE). During class switching, an activated B cell utilizes the enzyme activation-induced cytidine deaminase (AID) to introduce DNA double-strand breaks within a specific switch region. The broken ends of the DNA are then joined together through a process called class switch recombination (CSR), resulting in the deletion of the intervening DNA and the fusion of the upstream V(D)J region with a new downstream constant region gene, thereby altering the isotype of the expressed antibody.

Somatic hypermutation is a process that occurs in the immune system, specifically within B cells, which are a type of white blood cell responsible for producing antibodies. This process involves the introduction of point mutations into the immunoglobulin (Ig) genes, which encode for the variable regions of antibodies.

Somatic hypermutation occurs in the germinal centers of lymphoid follicles in response to antigen stimulation. The activation-induced cytidine deaminase (AID) enzyme is responsible for initiating this process by deaminating cytosines to uracils in the Ig genes. This leads to the introduction of point mutations during DNA replication and repair, which can result in changes to the antibody's binding affinity for the antigen.

The somatic hypermutation process allows for the selection of B cells with higher affinity antibodies that can better recognize and neutralize pathogens. This is an important mechanism for the development of humoral immunity and the generation of long-lived memory B cells. However, excessive or aberrant somatic hypermutation can also contribute to the development of certain types of B cell malignancies, such as lymphomas and leukemias.

I'm sorry for any confusion, but "Schizosaccharomyces pombe proteins" is not a medical term or concept. Schizosaccharomyces pombe is a type of single-celled microorganism called a yeast, which is often used as a model organism in scientific research. Proteins are complex molecules that do most of the work in cells and are necessary for the structure, function, and regulation of the body's tissues and organs.

In the context of scientific research, "Schizosaccharomyces pombe proteins" would refer to the specific proteins found in or studied using this particular type of yeast. These proteins may have similarities to human proteins and can be used to help understand basic biological processes, as well as diseases that occur in humans. However, it is important to note that while research using model organisms like Schizosaccharomyces pombe has led to many important discoveries, the findings may not always translate directly to humans.

The G2 phase cell cycle checkpoint is a point in the cell cycle, specifically in the G2 phase, where the cell checks for any DNA damage or other issues that may have occurred during the DNA synthesis phase (S phase) before proceeding to mitosis. This checkpoint serves as a quality control mechanism to ensure that the genetic material is accurately and completely replicated and that the cell is ready to divide. If DNA damage or other problems are detected, the cell cycle is halted at the G2 checkpoint until the issues can be resolved. If the damage is too severe or cannot be repaired, the cell may undergo programmed cell death (apoptosis) to prevent the propagation of potentially harmful mutations.

Crossing over, genetic is a process that occurs during meiosis, where homologous chromosomes exchange genetic material with each other. It is a crucial mechanism for generating genetic diversity in sexually reproducing organisms.

Here's a more detailed explanation:

During meiosis, homologous chromosomes pair up and align closely with each other. At this point, sections of the chromosomes can break off and reattach to the corresponding section on the homologous chromosome. This exchange of genetic material is called crossing over or genetic recombination.

The result of crossing over is that the two resulting chromosomes are no longer identical to each other or to the original chromosomes. Instead, they contain a unique combination of genetic material from both parents. Crossing over can lead to new combinations of alleles (different forms of the same gene) and can increase genetic diversity in the population.

Crossing over is a random process, so the location and frequency of crossover events vary between individuals and between chromosomes. The number and position of crossovers can affect the likelihood that certain genes will be inherited together or separated, which is an important consideration in genetic mapping and breeding studies.

Holliday junction resolvases are a type of enzyme that are involved in the process of genetic recombination. They are named after Robin Holliday, who first proposed the existence of a structure called a Holliday junction during genetic recombination.

A Holliday junction is a four-way DNA structure that forms when two DNA molecules exchange genetic material during recombination. The junction is held together by hydrogen bonds between complementary base pairs, and it can move along the DNA molecules through a process called branch migration.

Holliday junction resolvases are responsible for cleaving the DNA strands at the Holliday junction, resolving the structure into two separate DNA molecules. They do this by introducing nicks in the phosphodiester backbone of the DNA strands on either side of the junction and then joining the broken ends together. This results in the exchange of genetic material between the two original DNA molecules.

There are several different types of Holliday junction resolvases, including the bacterial RuvC and RecU enzymes, as well as the eukaryotic Flap endonuclease 1 (FEN1) and XPF/ERCC1 complexes. These enzymes have different specificities for cleaving the DNA strands at the Holliday junction, but they all play important roles in ensuring that genetic recombination occurs accurately and efficiently.

Gene targeting is a research technique in molecular biology used to precisely modify specific genes within the genome of an organism. This technique allows scientists to study gene function by creating targeted genetic changes, such as insertions, deletions, or mutations, in a specific gene of interest. The process typically involves the use of engineered nucleases, such as CRISPR-Cas9 or TALENs, to introduce double-stranded breaks at desired locations within the genome. These breaks are then repaired by the cell's own DNA repair machinery, often leading to the incorporation of designed changes in the targeted gene. Gene targeting is a powerful tool for understanding gene function and has wide-ranging applications in basic research, agriculture, and therapeutic development.

Chromatin assembly and disassembly refer to the processes by which chromatin, the complex of DNA, histone proteins, and other molecules that make up chromosomes, is organized within the nucleus of a eukaryotic cell.

Chromatin assembly refers to the process by which DNA wraps around histone proteins to form nucleosomes, which are then packed together to form higher-order structures. This process is essential for compacting the vast amount of genetic material contained within the cell nucleus and for regulating gene expression. Chromatin assembly is mediated by a variety of protein complexes, including the histone chaperones and ATP-dependent chromatin remodeling enzymes.

Chromatin disassembly, on the other hand, refers to the process by which these higher-order structures are disassembled during cell division, allowing for the equal distribution of genetic material to daughter cells. This process is mediated by phosphorylation of histone proteins by kinases, which leads to the dissociation of nucleosomes and the decondensation of chromatin.

Both Chromatin assembly and disassembly are dynamic and highly regulated processes that play crucial roles in the maintenance of genome stability and the regulation of gene expression.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Biological models, also known as physiological models or organismal models, are simplified representations of biological systems, processes, or mechanisms that are used to understand and explain the underlying principles and relationships. These models can be theoretical (conceptual or mathematical) or physical (such as anatomical models, cell cultures, or animal models). They are widely used in biomedical research to study various phenomena, including disease pathophysiology, drug action, and therapeutic interventions.

Examples of biological models include:

1. Mathematical models: These use mathematical equations and formulas to describe complex biological systems or processes, such as population dynamics, metabolic pathways, or gene regulation networks. They can help predict the behavior of these systems under different conditions and test hypotheses about their underlying mechanisms.
2. Cell cultures: These are collections of cells grown in a controlled environment, typically in a laboratory dish or flask. They can be used to study cellular processes, such as signal transduction, gene expression, or metabolism, and to test the effects of drugs or other treatments on these processes.
3. Animal models: These are living organisms, usually vertebrates like mice, rats, or non-human primates, that are used to study various aspects of human biology and disease. They can provide valuable insights into the pathophysiology of diseases, the mechanisms of drug action, and the safety and efficacy of new therapies.
4. Anatomical models: These are physical representations of biological structures or systems, such as plastic models of organs or tissues, that can be used for educational purposes or to plan surgical procedures. They can also serve as a basis for developing more sophisticated models, such as computer simulations or 3D-printed replicas.

Overall, biological models play a crucial role in advancing our understanding of biology and medicine, helping to identify new targets for therapeutic intervention, develop novel drugs and treatments, and improve human health.

BRCA2 (pronounced "braca two") protein is a tumor suppressor protein that plays a crucial role in repairing damaged DNA in cells. It is encoded by the BRCA2 gene, which is located on chromosome 13. Mutations in the BRCA2 gene have been associated with an increased risk of developing certain types of cancer, particularly breast and ovarian cancer in women, and breast and prostate cancer in men.

The BRCA2 protein interacts with other proteins to repair double-strand breaks in DNA through a process called homologous recombination. When the BRCA2 protein is not functioning properly due to a mutation, damaged DNA may not be repaired correctly, leading to genetic instability and an increased risk of cancer.

It's important to note that not all people with BRCA2 mutations will develop cancer, but their risk is higher than those without the mutation. Genetic testing can identify individuals who have inherited a mutation in the BRCA2 gene and help guide medical management and screening recommendations.

'Escherichia coli' (E. coli) is a type of gram-negative, facultatively anaerobic, rod-shaped bacterium that commonly inhabits the intestinal tract of humans and warm-blooded animals. It is a member of the family Enterobacteriaceae and one of the most well-studied prokaryotic model organisms in molecular biology.

While most E. coli strains are harmless and even beneficial to their hosts, some serotypes can cause various forms of gastrointestinal and extraintestinal illnesses in humans and animals. These pathogenic strains possess virulence factors that enable them to colonize and damage host tissues, leading to diseases such as diarrhea, urinary tract infections, pneumonia, and sepsis.

E. coli is a versatile organism with remarkable genetic diversity, which allows it to adapt to various environmental niches. It can be found in water, soil, food, and various man-made environments, making it an essential indicator of fecal contamination and a common cause of foodborne illnesses. The study of E. coli has contributed significantly to our understanding of fundamental biological processes, including DNA replication, gene regulation, and protein synthesis.

Naphthacenes are hydrocarbon compounds that consist of a naphthalene ring fused to two additional benzene rings. They belong to the class of polycyclic aromatic hydrocarbons (PAHs) and have been studied for their potential carcinogenic properties. Naphthacenes can be found in various environmental sources, including air pollution from vehicle emissions and cigarette smoke. However, it's important to note that specific medical definitions related to diseases or conditions are not typically associated with naphthacenes.

Intracellular signaling peptides and proteins are molecules that play a crucial role in transmitting signals within cells, which ultimately lead to changes in cell behavior or function. These signals can originate from outside the cell (extracellular) or within the cell itself. Intracellular signaling molecules include various types of peptides and proteins, such as:

1. G-protein coupled receptors (GPCRs): These are seven-transmembrane domain receptors that bind to extracellular signaling molecules like hormones, neurotransmitters, or chemokines. Upon activation, they initiate a cascade of intracellular signals through G proteins and secondary messengers.
2. Receptor tyrosine kinases (RTKs): These are transmembrane receptors that bind to growth factors, cytokines, or hormones. Activation of RTKs leads to autophosphorylation of specific tyrosine residues, creating binding sites for intracellular signaling proteins such as adapter proteins, phosphatases, and enzymes like Ras, PI3K, and Src family kinases.
3. Second messenger systems: Intracellular second messengers are small molecules that amplify and propagate signals within the cell. Examples include cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), diacylglycerol (DAG), inositol triphosphate (IP3), calcium ions (Ca2+), and nitric oxide (NO). These second messengers activate or inhibit various downstream effectors, leading to changes in cellular responses.
4. Signal transduction cascades: Intracellular signaling proteins often form complex networks of interacting molecules that relay signals from the plasma membrane to the nucleus. These cascades involve kinases (protein kinases A, B, C, etc.), phosphatases, and adapter proteins, which ultimately regulate gene expression, cell cycle progression, metabolism, and other cellular processes.
5. Ubiquitination and proteasome degradation: Intracellular signaling pathways can also control protein stability by modulating ubiquitin-proteasome degradation. E3 ubiquitin ligases recognize specific substrates and conjugate them with ubiquitin molecules, targeting them for proteasomal degradation. This process regulates the abundance of key signaling proteins and contributes to signal termination or amplification.

In summary, intracellular signaling pathways involve a complex network of interacting proteins that relay signals from the plasma membrane to various cellular compartments, ultimately regulating gene expression, metabolism, and other cellular processes. Dysregulation of these pathways can contribute to disease development and progression, making them attractive targets for therapeutic intervention.

"Cricetulus" is a genus of rodents that includes several species of hamsters. These small, burrowing animals are native to Asia and have a body length of about 8-15 centimeters, with a tail that is usually shorter than the body. They are characterized by their large cheek pouches, which they use to store food. Some common species in this genus include the Chinese hamster (Cricetulus griseus) and the Daurian hamster (Cricetulus dauuricus). These animals are often kept as pets or used in laboratory research.

B-lymphocytes, also known as B-cells, are a type of white blood cell that plays a key role in the immune system's response to infection. They are responsible for producing antibodies, which are proteins that help to neutralize or destroy pathogens such as bacteria and viruses.

When a B-lymphocyte encounters a pathogen, it becomes activated and begins to divide and differentiate into plasma cells, which produce and secrete large amounts of antibodies specific to the antigens on the surface of the pathogen. These antibodies bind to the pathogen, marking it for destruction by other immune cells such as neutrophils and macrophages.

B-lymphocytes also have a role in presenting antigens to T-lymphocytes, another type of white blood cell involved in the immune response. This helps to stimulate the activation and proliferation of T-lymphocytes, which can then go on to destroy infected cells or help to coordinate the overall immune response.

Overall, B-lymphocytes are an essential part of the adaptive immune system, providing long-lasting immunity to previously encountered pathogens and helping to protect against future infections.

I'm sorry for any confusion, but "Leukemia P388" is not a widely recognized medical term or a specific type of leukemia. The term "P388" is often used to refer to a particular type of mouse leukemia that is commonly used in laboratory research for testing potential anti-cancer drugs.

Leukemia, in general, is a type of cancer that originates in the bone marrow and results in an overproduction of abnormal white blood cells (leukocytes). These abnormal cells crowd out the healthy cells in the bone marrow, leading to a weakened immune system and various complications.

There are many different types of leukemia, classified based on the type of white blood cell affected (myeloid or lymphocytic) and the speed of progression (acute or chronic). If you're looking for information about a specific type of leukemia, I would be happy to help if you could provide more details.

Hydroxyurea is an antimetabolite drug that is primarily used in the treatment of myeloproliferative disorders such as chronic myelogenous leukemia (CML), essential thrombocythemia, and polycythemia vera. It works by interfering with the synthesis of DNA, which inhibits the growth of cancer cells.

In addition to its use in cancer therapy, hydroxyurea is also used off-label for the management of sickle cell disease. In this context, it helps to reduce the frequency and severity of painful vaso-occlusive crises by increasing the production of fetal hemoglobin (HbF), which decreases the formation of sickled red blood cells.

The medical definition of hydroxyurea is:

A hydantoin derivative and antimetabolite that inhibits ribonucleoside diphosphate reductase, thereby interfering with DNA synthesis. It has been used as an antineoplastic agent, particularly in the treatment of myeloproliferative disorders, and more recently for the management of sickle cell disease to reduce the frequency and severity of painful vaso-occlusive crises by increasing fetal hemoglobin production.

DNA-directed DNA polymerase is a type of enzyme that synthesizes new strands of DNA by adding nucleotides to an existing DNA template in a 5' to 3' direction. These enzymes are essential for DNA replication, repair, and recombination. They require a single-stranded DNA template, a primer with a free 3' hydroxyl group, and the four deoxyribonucleoside triphosphates (dNTPs) as substrates to carry out the polymerization reaction.

DNA polymerases also have proofreading activity, which allows them to correct errors that occur during DNA replication by removing mismatched nucleotides and replacing them with the correct ones. This helps ensure the fidelity of the genetic information passed from one generation to the next.

There are several different types of DNA polymerases, each with specific functions and characteristics. For example, DNA polymerase I is involved in both DNA replication and repair, while DNA polymerase III is the primary enzyme responsible for DNA replication in bacteria. In eukaryotic cells, DNA polymerase alpha, beta, gamma, delta, and epsilon have distinct roles in DNA replication, repair, and maintenance.

In situ nick-end labeling (ISEL, also known as TUNEL) is a technique used in pathology and molecular biology to detect DNA fragmentation, which is a characteristic of apoptotic cells (cells undergoing programmed cell death). The method involves labeling the 3'-hydroxyl termini of double or single stranded DNA breaks in situ (within tissue sections or individual cells) using modified nucleotides that are coupled to a detectable marker, such as a fluorophore or an enzyme. This technique allows for the direct visualization and quantification of apoptotic cells within complex tissues or cell populations.

DNA polymerase beta is a type of enzyme that plays a crucial role in the repair and maintenance of DNA in cells. It is a member of the DNA polymerase family, which are enzymes responsible for synthesizing new strands of DNA during replication and repair processes.

More specifically, DNA polymerase beta is involved in the base excision repair (BER) pathway, which is a mechanism for correcting damaged or mismatched bases in DNA. This enzyme functions by removing the damaged or incorrect base and replacing it with a new, correct one, using the undamaged strand as a template.

DNA polymerase beta has several key features that make it well-suited to its role in BER. It is highly processive, meaning that it can add many nucleotides to the growing DNA chain before dissociating from the template. It also has a high catalytic rate and is able to efficiently incorporate new nucleotides into the DNA chain.

Overall, DNA polymerase beta is an essential enzyme for maintaining genomic stability and preventing the accumulation of mutations in cells. Defects in this enzyme have been linked to various human diseases, including cancer and neurodegenerative disorders.

'Tumor cells, cultured' refers to the process of removing cancerous cells from a tumor and growing them in controlled laboratory conditions. This is typically done by isolating the tumor cells from a patient's tissue sample, then placing them in a nutrient-rich environment that promotes their growth and multiplication.

The resulting cultured tumor cells can be used for various research purposes, including the study of cancer biology, drug development, and toxicity testing. They provide a valuable tool for researchers to better understand the behavior and characteristics of cancer cells outside of the human body, which can lead to the development of more effective cancer treatments.

It is important to note that cultured tumor cells may not always behave exactly the same way as they do in the human body, so findings from cell culture studies must be validated through further research, such as animal models or clinical trials.

Fungal proteins are a type of protein that is specifically produced and present in fungi, which are a group of eukaryotic organisms that include microorganisms such as yeasts and molds. These proteins play various roles in the growth, development, and survival of fungi. They can be involved in the structure and function of fungal cells, metabolism, pathogenesis, and other cellular processes. Some fungal proteins can also have important implications for human health, both in terms of their potential use as therapeutic targets and as allergens or toxins that can cause disease.

Fungal proteins can be classified into different categories based on their functions, such as enzymes, structural proteins, signaling proteins, and toxins. Enzymes are proteins that catalyze chemical reactions in fungal cells, while structural proteins provide support and protection for the cell. Signaling proteins are involved in communication between cells and regulation of various cellular processes, and toxins are proteins that can cause harm to other organisms, including humans.

Understanding the structure and function of fungal proteins is important for developing new treatments for fungal infections, as well as for understanding the basic biology of fungi. Research on fungal proteins has led to the development of several antifungal drugs that target specific fungal enzymes or other proteins, providing effective treatment options for a range of fungal diseases. Additionally, further study of fungal proteins may reveal new targets for drug development and help improve our ability to diagnose and treat fungal infections.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Gene deletion is a type of mutation where a segment of DNA, containing one or more genes, is permanently lost or removed from a chromosome. This can occur due to various genetic mechanisms such as homologous recombination, non-homologous end joining, or other types of genomic rearrangements.

The deletion of a gene can have varying effects on the organism, depending on the function of the deleted gene and its importance for normal physiological processes. If the deleted gene is essential for survival, the deletion may result in embryonic lethality or developmental abnormalities. However, if the gene is non-essential or has redundant functions, the deletion may not have any noticeable effects on the organism's phenotype.

Gene deletions can also be used as a tool in genetic research to study the function of specific genes and their role in various biological processes. For example, researchers may use gene deletion techniques to create genetically modified animal models to investigate the impact of gene deletion on disease progression or development.

I'm happy to help! However, I believe there may be a slight mistake in your question. The abbreviation "cdc" is not typically associated with genetics or genes in the context of medical definitions.

If you meant to ask for a definition of "genes," here it is:

Genes are segments of DNA (deoxyribonucleic acid) that contain the instructions for the development, function, and reproduction of all living organisms. They are the basic units of heredity, passed down from one generation to the next. Genes encode specific proteins or RNA molecules that play critical roles in the structure, function, and regulation of the body's cells, tissues, and organs.

If you had a different term in mind, please let me know, and I will be happy to provide a definition for it!

Antibiotics are a type of medication used to treat infections caused by bacteria. They work by either killing the bacteria or inhibiting their growth.

Antineoplastics, also known as chemotherapeutic agents, are a class of drugs used to treat cancer. These medications target and destroy rapidly dividing cells, such as cancer cells, although they can also affect other quickly dividing cells in the body, such as those in the hair follicles or digestive tract, which can lead to side effects.

Antibiotics and antineoplastics are two different classes of drugs with distinct mechanisms of action and uses. It is important to use them appropriately and under the guidance of a healthcare professional.

Cross-linking reagents are chemical agents that are used to create covalent bonds between two or more molecules, creating a network of interconnected molecules known as a cross-linked structure. In the context of medical and biological research, cross-linking reagents are often used to stabilize protein structures, study protein-protein interactions, and develop therapeutic agents.

Cross-linking reagents work by reacting with functional groups on adjacent molecules, such as amino groups (-NH2) or sulfhydryl groups (-SH), to form a covalent bond between them. This can help to stabilize protein structures and prevent them from unfolding or aggregating.

There are many different types of cross-linking reagents, each with its own specificity and reactivity. Some common examples include glutaraldehyde, formaldehyde, disuccinimidyl suberate (DSS), and bis(sulfosuccinimidyl) suberate (BS3). The choice of cross-linking reagent depends on the specific application and the properties of the molecules being cross-linked.

It is important to note that cross-linking reagents can also have unintended effects, such as modifying or disrupting the function of the proteins they are intended to stabilize. Therefore, it is essential to use them carefully and with appropriate controls to ensure accurate and reliable results.

Immunoglobulin heavy chains (IgH) are proteins that make up the framework of antibodies, which are crucial components of the adaptive immune system. These heavy chains are produced by B cells and plasma cells, and they contain variable regions that can bind to specific antigens, as well as constant regions that determine the effector functions of the antibody.

The genes that encode for immunoglobulin heavy chains are located on chromosome 14 in humans, within a region known as the IgH locus. These genes undergo a complex process of rearrangement during B cell development, whereby different gene segments (V, D, and J) are joined together to create a unique variable region that can recognize a specific antigen. This process of gene rearrangement is critical for the diversity and specificity of the antibody response.

Therefore, the medical definition of 'Genes, Immunoglobulin Heavy Chain' refers to the set of genetic elements that encode for the immunoglobulin heavy chain proteins, and their complex process of rearrangement during B cell development.

Medical Definition of "Multiprotein Complexes" :

Multiprotein complexes are large molecular assemblies composed of two or more proteins that interact with each other to carry out specific cellular functions. These complexes can range from relatively simple dimers or trimers to massive structures containing hundreds of individual protein subunits. They are formed through a process known as protein-protein interaction, which is mediated by specialized regions on the protein surface called domains or motifs.

Multiprotein complexes play critical roles in many cellular processes, including signal transduction, gene regulation, DNA replication and repair, protein folding and degradation, and intracellular transport. The formation of these complexes is often dynamic and regulated in response to various stimuli, allowing for precise control of their function.

Disruption of multiprotein complexes can lead to a variety of diseases, including cancer, neurodegenerative disorders, and infectious diseases. Therefore, understanding the structure, composition, and regulation of these complexes is an important area of research in molecular biology and medicine.

Radiation tolerance, in the context of medicine and particularly radiation oncology, refers to the ability of tissues or organs to withstand and recover from exposure to ionizing radiation without experiencing significant damage or loss of function. It is often used to describe the maximum dose of radiation that can be safely delivered to a specific area of the body during radiotherapy treatments.

Radiation tolerance varies depending on the type and location of the tissue or organ. For example, some tissues such as the brain, spinal cord, and lungs have lower radiation tolerance than others like the skin or bone. Factors that can affect radiation tolerance include the total dose of radiation, the fractionation schedule (the number and size of radiation doses), the volume of tissue treated, and the individual patient's overall health and genetic factors.

Assessing radiation tolerance is critical in designing safe and effective radiotherapy plans for cancer patients, as excessive radiation exposure can lead to serious side effects such as radiation-induced injury, fibrosis, or even secondary malignancies.

Flap endonucleases are a type of enzyme that are involved in the repair of damaged DNA. They are named for their ability to cleave or cut the "flaps" of single-stranded DNA that extend beyond the ends of double-stranded DNA. These flaps can occur as a result of DNA damage, such as oxidation or exposure to UV light, or during the normal process of DNA replication.

Flap endonucleases play an important role in several DNA repair pathways, including base excision repair and nucleotide excision repair. In these pathways, the enzyme recognizes and cleaves the flaps, allowing for the damaged or incorrect nucleotides to be removed and replaced with correct ones.

Flap endonucleases are highly conserved across different species, indicating their important role in maintaining genomic stability. Defects in these enzymes have been linked to increased susceptibility to cancer and other diseases associated with DNA damage.

Mutagenesis is the process by which the genetic material (DNA or RNA) of an organism is changed in a way that can alter its phenotype, or observable traits. These changes, known as mutations, can be caused by various factors such as chemicals, radiation, or viruses. Some mutations may have no effect on the organism, while others can cause harm, including diseases and cancer. Mutagenesis is a crucial area of study in genetics and molecular biology, with implications for understanding evolution, genetic disorders, and the development of new medical treatments.

Mitomycin is an antineoplastic antibiotic derived from Streptomyces caespitosus. It is primarily used in cancer chemotherapy, particularly in the treatment of various carcinomas including gastrointestinal tract malignancies and breast cancer. Mitomycin works by forming cross-links in DNA, thereby inhibiting its replication and transcription, which ultimately leads to cell death.

In addition to its systemic use, mitomycin is also used topically in ophthalmology for the treatment of certain eye conditions such as glaucoma and various ocular surface disorders. The topical application of mitomycin can help reduce scarring and fibrosis by inhibiting the proliferation of fibroblasts.

It's important to note that mitomycin has a narrow therapeutic index, meaning there is only a small range between an effective dose and a toxic one. Therefore, its use should be closely monitored to minimize side effects, which can include myelosuppression, mucositis, alopecia, and potential secondary malignancies.

I'm sorry for any confusion, but "Genes, myc" is not a recognized medical term or abbreviation. It seems like there might be a misunderstanding or a missing word in the request. "Myc" could refer to the Myc family of transcription factors that are involved in cell growth and division, and are often deregulated in cancer. However, without more context, it's difficult to provide an accurate definition. If you could provide more information or clarify your question, I would be happy to help further!

Alkylating agents are a class of chemotherapy drugs that work by alkylating, or adding an alkyl group to, DNA molecules. This process can damage the DNA and prevent cancer cells from dividing and growing. Alkylating agents are often used to treat various types of cancer, including Hodgkin's lymphoma, non-Hodgkin's lymphoma, multiple myeloma, and solid tumors. Examples of alkylating agents include cyclophosphamide, melphalan, and chlorambucil. These drugs can have significant side effects, including nausea, vomiting, hair loss, and an increased risk of infection. They can also cause long-term damage to the heart, lungs, and reproductive system.

I'm sorry for any confusion, but "Razoxane" is not a medical term that has a widely accepted or specific definition in the field of medicine. It is possible that you may be referring to "razoxane," which is a medication used in the treatment of certain types of cancer. Razoxane is an antineoplastic agent, which means it is a drug that is used to treat cancer. It works by interfering with the formation of blood vessels that supply tumors, which can help to slow or stop the growth of the tumor.

It is important to note that the use of razoxane is not widely accepted and it is not a commonly used cancer treatment. It is typically used only in certain specific circumstances and when other treatments have not been effective. As with any medication, razoxane should be used under the close supervision of a healthcare professional, and it is important to be aware of the potential risks and benefits.

Bacterial DNA refers to the genetic material found in bacteria. It is composed of a double-stranded helix containing four nucleotide bases - adenine (A), thymine (T), guanine (G), and cytosine (C) - that are linked together by phosphodiester bonds. The sequence of these bases in the DNA molecule carries the genetic information necessary for the growth, development, and reproduction of bacteria.

Bacterial DNA is circular in most bacterial species, although some have linear chromosomes. In addition to the main chromosome, many bacteria also contain small circular pieces of DNA called plasmids that can carry additional genes and provide resistance to antibiotics or other environmental stressors.

Unlike eukaryotic cells, which have their DNA enclosed within a nucleus, bacterial DNA is present in the cytoplasm of the cell, where it is in direct contact with the cell's metabolic machinery. This allows for rapid gene expression and regulation in response to changing environmental conditions.

Superhelical DNA refers to a type of DNA structure that is formed when the double helix is twisted around itself. This occurs due to the presence of negative supercoiling, which results in an overtwisted state that can be described as having a greater number of helical turns than a relaxed circular DNA molecule.

Superhelical DNA is often found in bacterial and viral genomes, where it plays important roles in compacting the genome into a smaller volume and facilitating processes such as replication and transcription. The degree of supercoiling can affect the structure and function of DNA, with varying levels of supercoiling influencing the accessibility of specific regions of the genome to proteins and other regulatory factors.

Superhelical DNA is typically maintained in a stable state by topoisomerase enzymes, which introduce or remove twists in the double helix to regulate its supercoiling level. Changes in supercoiling can have significant consequences for cellular processes, as they can impact the expression of genes and the regulation of chromosome structure and function.

Mammalian chromosomes are thread-like structures that exist in the nucleus of mammalian cells, consisting of DNA, hist proteins, and RNA. They carry genetic information that is essential for the development and function of all living organisms. In mammals, each cell contains 23 pairs of chromosomes, for a total of 46 chromosomes, with one set inherited from the mother and the other from the father.

The chromosomes are typically visualized during cell division, where they condense and become visible under a microscope. Each chromosome is composed of two identical arms, separated by a constriction called the centromere. The short arm of the chromosome is labeled as "p," while the long arm is labeled as "q."

Mammalian chromosomes play a critical role in the transmission of genetic information from one generation to the next and are essential for maintaining the stability and integrity of the genome. Abnormalities in the number or structure of mammalian chromosomes can lead to various genetic disorders, including Down syndrome, Turner syndrome, and Klinefelter syndrome.

Micronuclei, chromosome-defective, refer to small additional nuclei that form during cell division when the genetic material is not properly divided between the two resulting daughter cells. These micronuclei can contain whole chromosomes or fragments of chromosomes that were not incorporated into either of the main nuclei during cell division. Chromosome-defective micronuclei are often associated with genomic instability, DNA damage, and chromosomal aberrations, which can lead to various health issues, including cancer and developmental defects. They can be used as a biomarker for genetic damage in cells and are commonly observed in response to exposure to mutagenic agents such as radiation or chemicals.

Cell death is the process by which cells cease to function and eventually die. There are several ways that cells can die, but the two most well-known and well-studied forms of cell death are apoptosis and necrosis.

Apoptosis is a programmed form of cell death that occurs as a normal and necessary process in the development and maintenance of healthy tissues. During apoptosis, the cell's DNA is broken down into small fragments, the cell shrinks, and the membrane around the cell becomes fragmented, allowing the cell to be easily removed by phagocytic cells without causing an inflammatory response.

Necrosis, on the other hand, is a form of cell death that occurs as a result of acute tissue injury or overwhelming stress. During necrosis, the cell's membrane becomes damaged and the contents of the cell are released into the surrounding tissue, causing an inflammatory response.

There are also other forms of cell death, such as autophagy, which is a process by which cells break down their own organelles and proteins to recycle nutrients and maintain energy homeostasis, and pyroptosis, which is a form of programmed cell death that occurs in response to infection and involves the activation of inflammatory caspases.

Cell death is an important process in many physiological and pathological processes, including development, tissue homeostasis, and disease. Dysregulation of cell death can contribute to the development of various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.

A micronucleus test is a type of genetic toxicology assay used to detect the presence of micronuclei in cells, which are small chromosomal fragments or whole chromosomes that have been missegregated during cell division. The test measures the frequency of micronuclei in cells exposed to a potential genotoxic agent, such as a chemical or radiation, and compares it to the frequency in untreated control cells.

The assay is typically performed on cultured mammalian cells, such as human lymphocytes or Chinese hamster ovary (CHO) cells, and involves exposing the cells to the test agent for a specific period of time, followed by staining and examination of the cells under a microscope. The micronuclei are identified based on their size, shape, and staining characteristics, and the frequency of micronucleated cells is calculated as a measure of genotoxic potential.

Micronucleus tests are widely used in regulatory toxicology to assess the genetic safety of chemicals, drugs, and other substances, and can provide valuable information on potential risks to human health. The test is also used in basic research to study the mechanisms of genotoxicity and chromosomal instability.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Electrophoresis, Agar Gel is a laboratory technique used to separate and analyze DNA, RNA, or proteins based on their size and electrical charge. In this method, the sample is mixed with agarose gel, a gelatinous substance derived from seaweed, and then solidified in a horizontal slab-like format. An electric field is applied to the gel, causing the negatively charged DNA or RNA molecules to migrate towards the positive electrode. The smaller molecules move faster through the gel than the larger ones, resulting in their separation based on size. This technique is widely used in molecular biology and genetics research, as well as in diagnostic testing for various genetic disorders.

DNA nucleotidyltransferases are a class of enzymes that catalyze the addition of one or more nucleotides to the 3'-hydroxyl end of a DNA molecule. These enzymes play important roles in various biological processes, including DNA repair, recombination, and replication.

The reaction catalyzed by DNA nucleotidyltransferases involves the transfer of a nucleotide triphosphate (NTP) to the 3'-hydroxyl end of a DNA molecule, resulting in the formation of a phosphodiester bond and the release of pyrophosphate. The enzymes can add a single nucleotide or multiple nucleotides, depending on the specific enzyme and its function.

DNA nucleotidyltransferases are classified into several subfamilies based on their sequence similarity and function, including polymerases, terminal transferases, and primases. These enzymes have been extensively studied for their potential applications in biotechnology and medicine, such as in DNA sequencing, diagnostics, and gene therapy.

CHO cells, or Chinese Hamster Ovary cells, are a type of immortalized cell line that are commonly used in scientific research and biotechnology. They were originally derived from the ovaries of a female Chinese hamster (Cricetulus griseus) in the 1950s.

CHO cells have several characteristics that make them useful for laboratory experiments. They can grow and divide indefinitely under appropriate conditions, which allows researchers to culture large quantities of them for study. Additionally, CHO cells are capable of expressing high levels of recombinant proteins, making them a popular choice for the production of therapeutic drugs, vaccines, and other biologics.

In particular, CHO cells have become a workhorse in the field of biotherapeutics, with many approved monoclonal antibody-based therapies being produced using these cells. The ability to genetically modify CHO cells through various methods has further expanded their utility in research and industrial applications.

It is important to note that while CHO cells are widely used in scientific research, they may not always accurately represent human cell behavior or respond to drugs and other compounds in the same way as human cells do. Therefore, results obtained using CHO cells should be validated in more relevant systems when possible.

Cell cycle checkpoints are control mechanisms that regulate the cell cycle and ensure the accurate and timely progression through different phases of the cell cycle. These checkpoints monitor specific cellular events, such as DNA replication and damage, chromosome separation, and proper attachment of the mitotic spindle to the chromosomes. If any of these events fail to occur properly or are delayed, the cell cycle checkpoints trigger a response that can halt the cell cycle until the problem is resolved. This helps to prevent cells with damaged or incomplete genomes from dividing and potentially becoming cancerous.

There are three main types of cell cycle checkpoints:

1. G1 Checkpoint: Also known as the restriction point, this checkpoint controls the transition from the G1 phase to the S phase of the cell cycle. It monitors the availability of nutrients, growth factors, and the integrity of the genome before allowing the cell to proceed into DNA replication.
2. G2 Checkpoint: This checkpoint regulates the transition from the G2 phase to the M phase of the cell cycle. It checks for completion of DNA replication and absence of DNA damage before allowing the cell to enter mitosis.
3. Mitotic (M) Checkpoint: Also known as the spindle assembly checkpoint, this checkpoint ensures that all chromosomes are properly attached to the mitotic spindle before anaphase begins. It prevents the separation of sister chromatids until all kinetochores are correctly attached and tension is established between them.

Cell cycle checkpoints play a crucial role in maintaining genomic stability, preventing tumorigenesis, and ensuring proper cell division. Dysregulation of these checkpoints can lead to various diseases, including cancer.

Tertiary protein structure refers to the three-dimensional arrangement of all the elements (polypeptide chains) of a single protein molecule. It is the highest level of structural organization and results from interactions between various side chains (R groups) of the amino acids that make up the protein. These interactions, which include hydrogen bonds, ionic bonds, van der Waals forces, and disulfide bridges, give the protein its unique shape and stability, which in turn determines its function. The tertiary structure of a protein can be stabilized by various factors such as temperature, pH, and the presence of certain ions. Any changes in these factors can lead to denaturation, where the protein loses its tertiary structure and thus its function.

Nucleic acid conformation refers to the three-dimensional structure that nucleic acids (DNA and RNA) adopt as a result of the bonding patterns between the atoms within the molecule. The primary structure of nucleic acids is determined by the sequence of nucleotides, while the conformation is influenced by factors such as the sugar-phosphate backbone, base stacking, and hydrogen bonding.

Two common conformations of DNA are the B-form and the A-form. The B-form is a right-handed helix with a diameter of about 20 Å and a pitch of 34 Å, while the A-form has a smaller diameter (about 18 Å) and a shorter pitch (about 25 Å). RNA typically adopts an A-form conformation.

The conformation of nucleic acids can have significant implications for their function, as it can affect their ability to interact with other molecules such as proteins or drugs. Understanding the conformational properties of nucleic acids is therefore an important area of research in molecular biology and medicine.

A "knockout" mouse is a genetically engineered mouse in which one or more genes have been deleted or "knocked out" using molecular biology techniques. This allows researchers to study the function of specific genes and their role in various biological processes, as well as potential associations with human diseases. The mice are generated by introducing targeted DNA modifications into embryonic stem cells, which are then used to create a live animal. Knockout mice have been widely used in biomedical research to investigate gene function, disease mechanisms, and potential therapeutic targets.

Antigen receptors are specialized proteins found on the surface of immune cells, particularly B cells and T cells. These receptors are responsible for recognizing and binding to specific antigens, which are foreign substances such as proteins, carbohydrates, or lipids that stimulate an immune response.

B cell receptors (BCRs) are membrane-bound antibodies that recognize and bind to native antigens. When a BCR binds to its specific antigen, it triggers a series of intracellular signals that lead to the activation and differentiation of the B cell into an antibody-secreting plasma cell.

T cell receptors (TCRs) are membrane-bound proteins found on T cells that recognize and bind to antigens presented in the context of major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells. TCRs can distinguish between self and non-self antigens, allowing T cells to mount an immune response against infected or cancerous cells while sparing healthy cells.

Overall, antigen receptors play a critical role in the adaptive immune system's ability to recognize and respond to a wide variety of foreign substances.

Protein kinases are a group of enzymes that play a crucial role in many cellular processes by adding phosphate groups to other proteins, a process known as phosphorylation. This modification can activate or deactivate the target protein's function, thereby regulating various signaling pathways within the cell. Protein kinases are essential for numerous biological functions, including metabolism, signal transduction, cell cycle progression, and apoptosis (programmed cell death). Abnormal regulation of protein kinases has been implicated in several diseases, such as cancer, diabetes, and neurological disorders.

Hydrogen peroxide (H2O2) is a colorless, odorless, clear liquid with a slightly sweet taste, although drinking it is harmful and can cause poisoning. It is a weak oxidizing agent and is used as an antiseptic and a bleaching agent. In diluted form, it is used to disinfect wounds and kill bacteria and viruses on the skin; in higher concentrations, it can be used to bleach hair or remove stains from clothing. It is also used as a propellant in rocketry and in certain industrial processes. Chemically, hydrogen peroxide is composed of two hydrogen atoms and two oxygen atoms, and it is structurally similar to water (H2O), with an extra oxygen atom. This gives it its oxidizing properties, as the additional oxygen can be released and used to react with other substances.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

Enzyme inhibitors are substances that bind to an enzyme and decrease its activity, preventing it from catalyzing a chemical reaction in the body. They can work by several mechanisms, including blocking the active site where the substrate binds, or binding to another site on the enzyme to change its shape and prevent substrate binding. Enzyme inhibitors are often used as drugs to treat various medical conditions, such as high blood pressure, abnormal heart rhythms, and bacterial infections. They can also be found naturally in some foods and plants, and can be used in research to understand enzyme function and regulation.

Antineoplastic agents are a class of drugs used to treat malignant neoplasms or cancer. These agents work by inhibiting the growth and proliferation of cancer cells, either by killing them or preventing their division and replication. Antineoplastic agents can be classified based on their mechanism of action, such as alkylating agents, antimetabolites, topoisomerase inhibitors, mitotic inhibitors, and targeted therapy agents.

Alkylating agents work by adding alkyl groups to DNA, which can cause cross-linking of DNA strands and ultimately lead to cell death. Antimetabolites interfere with the metabolic processes necessary for DNA synthesis and replication, while topoisomerase inhibitors prevent the relaxation of supercoiled DNA during replication. Mitotic inhibitors disrupt the normal functioning of the mitotic spindle, which is essential for cell division. Targeted therapy agents are designed to target specific molecular abnormalities in cancer cells, such as mutated oncogenes or dysregulated signaling pathways.

It's important to note that antineoplastic agents can also affect normal cells and tissues, leading to various side effects such as nausea, vomiting, hair loss, and myelosuppression (suppression of bone marrow function). Therefore, the use of these drugs requires careful monitoring and management of their potential adverse effects.

In situ hybridization, fluorescence (FISH) is a type of molecular cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes through the use of fluorescent probes. This technique allows for the direct visualization of genetic material at a cellular level, making it possible to identify chromosomal abnormalities such as deletions, duplications, translocations, and other rearrangements.

The process involves denaturing the DNA in the sample to separate the double-stranded molecules into single strands, then adding fluorescently labeled probes that are complementary to the target DNA sequence. The probe hybridizes to the complementary sequence in the sample, and the location of the probe is detected by fluorescence microscopy.

FISH has a wide range of applications in both clinical and research settings, including prenatal diagnosis, cancer diagnosis and monitoring, and the study of gene expression and regulation. It is a powerful tool for identifying genetic abnormalities and understanding their role in human disease.

Argininosuccinate Lyase is an enzyme that plays a crucial role in the urea cycle, which is the metabolic pathway responsible for eliminating excess nitrogen waste from the body. This enzyme is responsible for catalyzing the conversion of argininosuccinate into arginine and fumarate.

The urea cycle occurs primarily in the liver and helps to convert toxic ammonia, a byproduct of protein metabolism, into urea, which can be safely excreted in urine. Argininosuccinate lyase is essential for this process, as it helps to convert argininosuccinate, an intermediate compound in the cycle, into arginine, which can then be recycled back into the urea cycle or used for other physiological processes.

Deficiencies in argininosuccinate lyase can lead to a rare genetic disorder known as citrullinemia, which is characterized by elevated levels of citrulline and ammonia in the blood, as well as neurological symptoms such as seizures, developmental delays, and intellectual disability. Treatment for citrullinemia typically involves a low-protein diet, supplementation with arginine and other essential amino acids, and in some cases, liver transplantation.

Zinostatin is not a widely recognized or commonly used term in medicine. However, it appears to be a brand name for a formulation of the anti-cancer drug Neocarzinostatin (NCS). Neocarzinostatin is a protein produced by the bacterium Streptomyces carzinostaticus and has been studied for its potential to inhibit the growth of various types of cancer cells.

Zinostatin is specifically used in the treatment of hepatocellular carcinoma (HCC), which is a type of liver cancer. It is administered via arterial infusion, where the drug is delivered directly into the hepatic artery that supplies blood to the liver. This method allows for higher concentrations of the drug to reach the tumor site while minimizing systemic exposure and potential side effects.

It's important to note that medical terminology can vary by region and context, so it's possible that "Zinostatin" may not be a term used in all medical communities or for all purposes. Always consult with a healthcare professional or trusted medical source for accurate information.

Chromosome fragility refers to the susceptibility of specific regions on chromosomes to break or become unstable during cell division. These fragile sites are prone to forming gaps or breaks in the chromosome structure, which can lead to genetic rearrangements, including deletions, duplications, or translocations.

Chromosome fragility is often associated with certain genetic disorders and syndromes. For example, the most common fragile site in human chromosomes is FRAXA, located on the X chromosome, which is linked to Fragile X Syndrome, a leading cause of inherited intellectual disability and autism.

Environmental factors such as exposure to chemicals or radiation can also increase chromosome fragility, leading to an increased risk of genetic mutations and diseases.

Oligonucleotides are short sequences of nucleotides, the building blocks of DNA and RNA. They typically contain fewer than 100 nucleotides, and can be synthesized chemically to have specific sequences. Oligonucleotides are used in a variety of applications in molecular biology, including as probes for detecting specific DNA or RNA sequences, as inhibitors of gene expression, and as components of diagnostic tests and therapies. They can also be used in the study of protein-nucleic acid interactions and in the development of new drugs.

Chromosome segregation is the process that occurs during cell division (mitosis or meiosis) where replicated chromosomes are separated and distributed equally into two daughter cells. Each chromosome consists of two sister chromatids, which are identical copies of genetic material. During chromosome segregation, these sister chromatids are pulled apart by a structure called the mitotic spindle and moved to opposite poles of the cell. This ensures that each new cell receives one copy of each chromosome, preserving the correct number and composition of chromosomes in the organism.

Lymphocytes are a type of white blood cell that is an essential part of the immune system. They are responsible for recognizing and responding to potentially harmful substances such as viruses, bacteria, and other foreign invaders. There are two main types of lymphocytes: B-lymphocytes (B-cells) and T-lymphocytes (T-cells).

B-lymphocytes produce antibodies, which are proteins that help to neutralize or destroy foreign substances. When a B-cell encounters a foreign substance, it becomes activated and begins to divide and differentiate into plasma cells, which produce and secrete large amounts of antibodies. These antibodies bind to the foreign substance, marking it for destruction by other immune cells.

T-lymphocytes, on the other hand, are involved in cell-mediated immunity. They directly attack and destroy infected cells or cancerous cells. T-cells can also help to regulate the immune response by producing chemical signals that activate or inhibit other immune cells.

Lymphocytes are produced in the bone marrow and mature in either the bone marrow (B-cells) or the thymus gland (T-cells). They circulate throughout the body in the blood and lymphatic system, where they can be found in high concentrations in lymph nodes, the spleen, and other lymphoid organs.

Abnormalities in the number or function of lymphocytes can lead to a variety of immune-related disorders, including immunodeficiency diseases, autoimmune disorders, and cancer.

Diploidy is a term used in genetics to describe the state of having two sets of chromosomes in each cell. In diploid organisms, one set of chromosomes is inherited from each parent, resulting in a total of 2 sets of chromosomes.

In humans, for example, most cells are diploid and contain 46 chromosomes arranged in 23 pairs. This includes 22 pairs of autosomal chromosomes and one pair of sex chromosomes (XX in females or XY in males). Diploidy is a characteristic feature of many complex organisms, including animals, plants, and fungi.

Diploid cells can undergo a process called meiosis, which results in the formation of haploid cells that contain only one set of chromosomes. These haploid cells can then combine with other haploid cells during fertilization to form a new diploid organism.

Abnormalities in diploidy can lead to genetic disorders, such as Down syndrome, which occurs when an individual has three copies of chromosome 21 instead of the typical two. This extra copy of the chromosome can result in developmental delays and intellectual disabilities.

Cell division is the process by which a single eukaryotic cell (a cell with a true nucleus) divides into two identical daughter cells. This complex process involves several stages, including replication of DNA, separation of chromosomes, and division of the cytoplasm. There are two main types of cell division: mitosis and meiosis.

Mitosis is the type of cell division that results in two genetically identical daughter cells. It is a fundamental process for growth, development, and tissue repair in multicellular organisms. The stages of mitosis include prophase, prometaphase, metaphase, anaphase, and telophase, followed by cytokinesis, which divides the cytoplasm.

Meiosis, on the other hand, is a type of cell division that occurs in the gonads (ovaries and testes) during the production of gametes (sex cells). Meiosis results in four genetically unique daughter cells, each with half the number of chromosomes as the parent cell. This process is essential for sexual reproduction and genetic diversity. The stages of meiosis include meiosis I and meiosis II, which are further divided into prophase, prometaphase, metaphase, anaphase, and telophase.

In summary, cell division is the process by which a single cell divides into two daughter cells, either through mitosis or meiosis. This process is critical for growth, development, tissue repair, and sexual reproduction in multicellular organisms.

Signal transduction is the process by which a cell converts an extracellular signal, such as a hormone or neurotransmitter, into an intracellular response. This involves a series of molecular events that transmit the signal from the cell surface to the interior of the cell, ultimately resulting in changes in gene expression, protein activity, or metabolism.

The process typically begins with the binding of the extracellular signal to a receptor located on the cell membrane. This binding event activates the receptor, which then triggers a cascade of intracellular signaling molecules, such as second messengers, protein kinases, and ion channels. These molecules amplify and propagate the signal, ultimately leading to the activation or inhibition of specific cellular responses.

Signal transduction pathways are highly regulated and can be modulated by various factors, including other signaling molecules, post-translational modifications, and feedback mechanisms. Dysregulation of these pathways has been implicated in a variety of diseases, including cancer, diabetes, and neurological disorders.

Fungal genes refer to the genetic material present in fungi, which are eukaryotic organisms that include microorganisms such as yeasts and molds, as well as larger organisms like mushrooms. The genetic material of fungi is composed of DNA, just like in other eukaryotes, and is organized into chromosomes located in the nucleus of the cell.

Fungal genes are segments of DNA that contain the information necessary to produce proteins and RNA molecules required for various cellular functions. These genes are transcribed into messenger RNA (mRNA) molecules, which are then translated into proteins by ribosomes in the cytoplasm.

Fungal genomes have been sequenced for many species, revealing a diverse range of genes that encode proteins involved in various cellular processes such as metabolism, signaling, and regulation. Comparative genomic analyses have also provided insights into the evolutionary relationships among different fungal lineages and have helped to identify unique genetic features that distinguish fungi from other eukaryotes.

Understanding fungal genes and their functions is essential for advancing our knowledge of fungal biology, as well as for developing new strategies to control fungal pathogens that can cause diseases in humans, animals, and plants.

Small interfering RNA (siRNA) is a type of short, double-stranded RNA molecule that plays a role in the RNA interference (RNAi) pathway. The RNAi pathway is a natural cellular process that regulates gene expression by targeting and destroying specific messenger RNA (mRNA) molecules, thereby preventing the translation of those mRNAs into proteins.

SiRNAs are typically 20-25 base pairs in length and are generated from longer double-stranded RNA precursors called hairpin RNAs or dsRNAs by an enzyme called Dicer. Once generated, siRNAs associate with a protein complex called the RNA-induced silencing complex (RISC), which uses one strand of the siRNA (the guide strand) to recognize and bind to complementary sequences in the target mRNA. The RISC then cleaves the target mRNA, leading to its degradation and the inhibition of protein synthesis.

SiRNAs have emerged as a powerful tool for studying gene function and have shown promise as therapeutic agents for a variety of diseases, including viral infections, cancer, and genetic disorders. However, their use as therapeutics is still in the early stages of development, and there are challenges associated with delivering siRNAs to specific cells and tissues in the body.

DNA primers are short single-stranded DNA molecules that serve as a starting point for DNA synthesis. They are typically used in laboratory techniques such as the polymerase chain reaction (PCR) and DNA sequencing. The primer binds to a complementary sequence on the DNA template through base pairing, providing a free 3'-hydroxyl group for the DNA polymerase enzyme to add nucleotides and synthesize a new strand of DNA. This allows for specific and targeted amplification or analysis of a particular region of interest within a larger DNA molecule.

'Escherichia coli (E. coli) proteins' refer to the various types of proteins that are produced and expressed by the bacterium Escherichia coli. These proteins play a critical role in the growth, development, and survival of the organism. They are involved in various cellular processes such as metabolism, DNA replication, transcription, translation, repair, and regulation.

E. coli is a gram-negative, facultative anaerobe that is commonly found in the intestines of warm-blooded organisms. It is widely used as a model organism in scientific research due to its well-studied genetics, rapid growth, and ability to be easily manipulated in the laboratory. As a result, many E. coli proteins have been identified, characterized, and studied in great detail.

Some examples of E. coli proteins include enzymes involved in carbohydrate metabolism such as lactase, sucrase, and maltose; proteins involved in DNA replication such as the polymerases, single-stranded binding proteins, and helicases; proteins involved in transcription such as RNA polymerase and sigma factors; proteins involved in translation such as ribosomal proteins, tRNAs, and aminoacyl-tRNA synthetases; and regulatory proteins such as global regulators, two-component systems, and transcription factors.

Understanding the structure, function, and regulation of E. coli proteins is essential for understanding the basic biology of this important organism, as well as for developing new strategies for combating bacterial infections and improving industrial processes involving bacteria.

Doxorubicin is a type of chemotherapy medication known as an anthracycline. It works by interfering with the DNA in cancer cells, which prevents them from growing and multiplying. Doxorubicin is used to treat a wide variety of cancers, including leukemia, lymphoma, breast cancer, lung cancer, ovarian cancer, and many others. It may be given alone or in combination with other chemotherapy drugs.

Doxorubicin is usually administered through a vein (intravenously) and can cause side effects such as nausea, vomiting, hair loss, mouth sores, and increased risk of infection. It can also cause damage to the heart muscle, which can lead to heart failure in some cases. For this reason, doctors may monitor patients' heart function closely while they are receiving doxorubicin treatment.

It is important for patients to discuss the potential risks and benefits of doxorubicin therapy with their healthcare provider before starting treatment.

Fluorescence microscopy is a type of microscopy that uses fluorescent dyes or proteins to highlight and visualize specific components within a sample. In this technique, the sample is illuminated with high-energy light, typically ultraviolet (UV) or blue light, which excites the fluorescent molecules causing them to emit lower-energy, longer-wavelength light, usually visible light in the form of various colors. This emitted light is then collected by the microscope and detected to produce an image.

Fluorescence microscopy has several advantages over traditional brightfield microscopy, including the ability to visualize specific structures or molecules within a complex sample, increased sensitivity, and the potential for quantitative analysis. It is widely used in various fields of biology and medicine, such as cell biology, neuroscience, and pathology, to study the structure, function, and interactions of cells and proteins.

There are several types of fluorescence microscopy techniques, including widefield fluorescence microscopy, confocal microscopy, two-photon microscopy, and total internal reflection fluorescence (TIRF) microscopy, each with its own strengths and limitations. These techniques can provide valuable insights into the behavior of cells and proteins in health and disease.

Proliferating Cell Nuclear Antigen (PCNA) is a protein that plays an essential role in the process of DNA replication and repair in eukaryotic cells. It functions as a cofactor for DNA polymerase delta, enhancing its activity during DNA synthesis. PCNA forms a sliding clamp around DNA, allowing it to move along the template and coordinate the actions of various enzymes involved in DNA metabolism.

PCNA is often used as a marker for cell proliferation because its levels increase in cells that are actively dividing or have been stimulated to enter the cell cycle. Immunostaining techniques can be used to detect PCNA and determine the proliferative status of tissues or cultures. In this context, 'proliferating' refers to the rapid multiplication of cells through cell division.

HCT116 cells are a type of human colon cancer cell line that is widely used in scientific research. They were originally established in the early 1980s from a primary colon tumor that had metastasized to the liver. HCT116 cells are known for their stability, robust growth, and susceptibility to various genetic manipulations, making them a popular choice for studying cancer biology, drug discovery, and gene function.

These cells have several important features that make them useful in research. For example, they harbor mutations in key genes involved in colorectal cancer development, such as the adenomatous polyposis coli (APC) gene and the KRAS oncogene. Additionally, HCT116 cells can be easily cultured in the lab and are amenable to a variety of experimental techniques, including genetic modification, drug screening, and protein analysis.

It is important to note that while HCT116 cells provide valuable insights into colon cancer biology, they represent only one type of cancer cell line, and their behavior may not necessarily reflect the complexity of human tumors in vivo. Therefore, researchers must exercise caution when interpreting results obtained from these cells and consider other complementary approaches to validate their findings.

Antineoplastic agents, phytogenic, also known as plant-derived anticancer drugs, are medications that are derived from plants and used to treat cancer. These agents have natural origins and work by interfering with the growth and multiplication of cancer cells, helping to slow or stop the spread of the disease. Some examples of antineoplastic agents, phytogenic include paclitaxel (Taxol), vincristine, vinblastine, and etoposide. These drugs are often used in combination with other treatments such as surgery, radiation therapy, and other medications to provide a comprehensive approach to cancer care.

Flow cytometry is a medical and research technique used to measure physical and chemical characteristics of cells or particles, one cell at a time, as they flow in a fluid stream through a beam of light. The properties measured include:

* Cell size (light scatter)
* Cell internal complexity (granularity, also light scatter)
* Presence or absence of specific proteins or other molecules on the cell surface or inside the cell (using fluorescent antibodies or other fluorescent probes)

The technique is widely used in cell counting, cell sorting, protein engineering, biomarker discovery and monitoring disease progression, particularly in hematology, immunology, and cancer research.

In the context of medical and biological sciences, a "binding site" refers to a specific location on a protein, molecule, or cell where another molecule can attach or bind. This binding interaction can lead to various functional changes in the original protein or molecule. The other molecule that binds to the binding site is often referred to as a ligand, which can be a small molecule, ion, or even another protein.

The binding between a ligand and its target binding site can be specific and selective, meaning that only certain ligands can bind to particular binding sites with high affinity. This specificity plays a crucial role in various biological processes, such as signal transduction, enzyme catalysis, or drug action.

In the case of drug development, understanding the location and properties of binding sites on target proteins is essential for designing drugs that can selectively bind to these sites and modulate protein function. This knowledge can help create more effective and safer therapeutic options for various diseases.

Neoplasms are abnormal growths of cells or tissues in the body that serve no physiological function. They can be benign (non-cancerous) or malignant (cancerous). Benign neoplasms are typically slow growing and do not spread to other parts of the body, while malignant neoplasms are aggressive, invasive, and can metastasize to distant sites.

Neoplasms occur when there is a dysregulation in the normal process of cell division and differentiation, leading to uncontrolled growth and accumulation of cells. This can result from genetic mutations or other factors such as viral infections, environmental exposures, or hormonal imbalances.

Neoplasms can develop in any organ or tissue of the body and can cause various symptoms depending on their size, location, and type. Treatment options for neoplasms include surgery, radiation therapy, chemotherapy, immunotherapy, and targeted therapy, among others.

A fungal genome refers to the complete set of genetic material or DNA present in the cells of a fungus. It includes all the genes and non-coding regions that are essential for the growth, development, and survival of the organism. The fungal genome is typically haploid, meaning it contains only one set of chromosomes, unlike diploid genomes found in many animals and plants.

Fungal genomes vary widely in size and complexity, ranging from a few megabases to hundreds of megabases. They contain several types of genetic elements such as protein-coding genes, regulatory regions, repetitive elements, and mobile genetic elements like transposons. The study of fungal genomes can provide valuable insights into the evolution, biology, and pathogenicity of fungi, and has important implications for medical research, agriculture, and industrial applications.

A Structure-Activity Relationship (SAR) in the context of medicinal chemistry and pharmacology refers to the relationship between the chemical structure of a drug or molecule and its biological activity or effect on a target protein, cell, or organism. SAR studies aim to identify patterns and correlations between structural features of a compound and its ability to interact with a specific biological target, leading to a desired therapeutic response or undesired side effects.

By analyzing the SAR, researchers can optimize the chemical structure of lead compounds to enhance their potency, selectivity, safety, and pharmacokinetic properties, ultimately guiding the design and development of novel drugs with improved efficacy and reduced toxicity.

The G1 phase, or Gap 1 phase, is the first phase of the cell cycle, during which the cell grows in size and synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. During this phase, the cell also checks its growth and makes sure that it is large enough to proceed through the cell cycle. If the cell is not large enough, it will arrest in the G1 phase until it has grown sufficiently. The G1 phase is followed by the S phase, during which DNA replication occurs.

Southern blotting is a type of membrane-based blotting technique that is used in molecular biology to detect and locate specific DNA sequences within a DNA sample. This technique is named after its inventor, Edward M. Southern.

In Southern blotting, the DNA sample is first digested with one or more restriction enzymes, which cut the DNA at specific recognition sites. The resulting DNA fragments are then separated based on their size by gel electrophoresis. After separation, the DNA fragments are denatured to convert them into single-stranded DNA and transferred onto a nitrocellulose or nylon membrane.

Once the DNA has been transferred to the membrane, it is hybridized with a labeled probe that is complementary to the sequence of interest. The probe can be labeled with radioactive isotopes, fluorescent dyes, or chemiluminescent compounds. After hybridization, the membrane is washed to remove any unbound probe and then exposed to X-ray film (in the case of radioactive probes) or scanned (in the case of non-radioactive probes) to detect the location of the labeled probe on the membrane.

The position of the labeled probe on the membrane corresponds to the location of the specific DNA sequence within the original DNA sample. Southern blotting is a powerful tool for identifying and characterizing specific DNA sequences, such as those associated with genetic diseases or gene regulation.

Enzyme activation refers to the process by which an enzyme becomes biologically active and capable of carrying out its specific chemical or biological reaction. This is often achieved through various post-translational modifications, such as proteolytic cleavage, phosphorylation, or addition of cofactors or prosthetic groups to the enzyme molecule. These modifications can change the conformation or structure of the enzyme, exposing or creating a binding site for the substrate and allowing the enzymatic reaction to occur.

For example, in the case of proteolytic cleavage, an inactive precursor enzyme, known as a zymogen, is cleaved into its active form by a specific protease. This is seen in enzymes such as trypsin and chymotrypsin, which are initially produced in the pancreas as inactive precursors called trypsinogen and chymotrypsinogen, respectively. Once they reach the small intestine, they are activated by enteropeptidase, a protease that cleaves a specific peptide bond, releasing the active enzyme.

Phosphorylation is another common mechanism of enzyme activation, where a phosphate group is added to a specific serine, threonine, or tyrosine residue on the enzyme by a protein kinase. This modification can alter the conformation of the enzyme and create a binding site for the substrate, allowing the enzymatic reaction to occur.

Enzyme activation is a crucial process in many biological pathways, as it allows for precise control over when and where specific reactions take place. It also provides a mechanism for regulating enzyme activity in response to various signals and stimuli, such as hormones, neurotransmitters, or changes in the intracellular environment.

A "cell line, transformed" is a type of cell culture that has undergone a stable genetic alteration, which confers the ability to grow indefinitely in vitro, outside of the organism from which it was derived. These cells have typically been immortalized through exposure to chemical or viral carcinogens, or by introducing specific oncogenes that disrupt normal cell growth regulation pathways.

Transformed cell lines are widely used in scientific research because they offer a consistent and renewable source of biological material for experimentation. They can be used to study various aspects of cell biology, including signal transduction, gene expression, drug discovery, and toxicity testing. However, it is important to note that transformed cells may not always behave identically to their normal counterparts, and results obtained using these cells should be validated in more physiologically relevant systems when possible.

Immunoglobulins (Igs), also known as antibodies, are proteins produced by the immune system to recognize and neutralize foreign substances such as pathogens or toxins. They are composed of four polypeptide chains: two heavy chains and two light chains, which are held together by disulfide bonds. The variable regions of the heavy and light chains contain loops that form the antigen-binding site, allowing each Ig molecule to recognize a specific epitope (antigenic determinant) on an antigen.

Genes encoding immunoglobulins are located on chromosome 14 (light chain genes) and chromosomes 22 and 2 (heavy chain genes). The diversity of the immune system is generated through a process called V(D)J recombination, where variable (V), diversity (D), and joining (J) gene segments are randomly selected and assembled to form the variable regions of the heavy and light chains. This results in an enormous number of possible combinations, allowing the immune system to recognize and respond to a vast array of potential threats.

There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, each with distinct functions and structures. For example, IgG is the most abundant class in serum and provides long-term protection against pathogens, while IgA is found on mucosal surfaces and helps prevent the entry of pathogens into the body.

Western blotting is a laboratory technique used in molecular biology to detect and quantify specific proteins in a mixture of many different proteins. This technique is commonly used to confirm the expression of a protein of interest, determine its size, and investigate its post-translational modifications. The name "Western" blotting distinguishes this technique from Southern blotting (for DNA) and Northern blotting (for RNA).

The Western blotting procedure involves several steps:

1. Protein extraction: The sample containing the proteins of interest is first extracted, often by breaking open cells or tissues and using a buffer to extract the proteins.
2. Separation of proteins by electrophoresis: The extracted proteins are then separated based on their size by loading them onto a polyacrylamide gel and running an electric current through the gel (a process called sodium dodecyl sulfate-polyacrylamide gel electrophoresis or SDS-PAGE). This separates the proteins according to their molecular weight, with smaller proteins migrating faster than larger ones.
3. Transfer of proteins to a membrane: After separation, the proteins are transferred from the gel onto a nitrocellulose or polyvinylidene fluoride (PVDF) membrane using an electric current in a process called blotting. This creates a replica of the protein pattern on the gel but now immobilized on the membrane for further analysis.
4. Blocking: The membrane is then blocked with a blocking agent, such as non-fat dry milk or bovine serum albumin (BSA), to prevent non-specific binding of antibodies in subsequent steps.
5. Primary antibody incubation: A primary antibody that specifically recognizes the protein of interest is added and allowed to bind to its target protein on the membrane. This step may be performed at room temperature or 4°C overnight, depending on the antibody's properties.
6. Washing: The membrane is washed with a buffer to remove unbound primary antibodies.
7. Secondary antibody incubation: A secondary antibody that recognizes the primary antibody (often coupled to an enzyme or fluorophore) is added and allowed to bind to the primary antibody. This step may involve using a horseradish peroxidase (HRP)-conjugated or alkaline phosphatase (AP)-conjugated secondary antibody, depending on the detection method used later.
8. Washing: The membrane is washed again to remove unbound secondary antibodies.
9. Detection: A detection reagent is added to visualize the protein of interest by detecting the signal generated from the enzyme-conjugated or fluorophore-conjugated secondary antibody. This can be done using chemiluminescent, colorimetric, or fluorescent methods.
10. Analysis: The resulting image is analyzed to determine the presence and quantity of the protein of interest in the sample.

Western blotting is a powerful technique for identifying and quantifying specific proteins within complex mixtures. It can be used to study protein expression, post-translational modifications, protein-protein interactions, and more. However, it requires careful optimization and validation to ensure accurate and reproducible results.

Immunoglobulin heavy chains are proteins that make up the framework of antibodies, which are Y-shaped immune proteins. These heavy chains, along with light chains, form the antigen-binding sites of an antibody, which recognize and bind to specific foreign substances (antigens) in order to neutralize or remove them from the body.

The heavy chain is composed of a variable region, which contains the antigen-binding site, and constant regions that determine the class and function of the antibody. There are five classes of immunoglobulins (IgA, IgD, IgE, IgG, and IgM) that differ in their heavy chain constant regions and therefore have different functions in the immune response.

Immunoglobulin heavy chains are synthesized by B cells, a type of white blood cell involved in the adaptive immune response. The genetic rearrangement of immunoglobulin heavy chain genes during B cell development results in the production of a vast array of different antibodies with unique antigen-binding sites, allowing for the recognition and elimination of a wide variety of pathogens.

DNA mismatch repair (MMR) is a cellular process that helps to correct errors that occur during DNA replication and recombination. This mechanism plays a critical role in maintaining the stability of the genome by reducing the rate of mutations.

The MMR system recognizes and repairs base-base mismatches and small insertions or deletions (indels) that can arise due to slippage of DNA polymerase during replication. The process involves several proteins, including MutSα or MutSβ, which recognize the mismatch, and MutLα, which acts as a endonuclease to cleave the DNA near the mismatch. Excision of the mismatched region is then carried out by exonucleases, followed by resynthesis of the repaired strand using the correct template.

Defects in MMR genes have been linked to various human diseases, including hereditary nonpolyposis colorectal cancer (HNPCC) and other types of cancer. In HNPCC, mutations in MMR genes lead to an accumulation of mutations in critical genes, which can ultimately result in the development of cancer.

Telomerase is an enzyme that adds repetitive DNA sequences (telomeres) to the ends of chromosomes, which are lost during each cell division due to the incomplete replication of the ends of linear chromosomes. Telomerase is not actively present in most somatic cells, but it is highly expressed in germ cells and stem cells, allowing them to divide indefinitely. However, in many types of cancer cells, telomerase is abnormally activated, which leads to the maintenance or lengthening of telomeres, contributing to their unlimited replicative potential and tumorigenesis.

Cellular aging, also known as cellular senescence, is a natural process that occurs as cells divide and grow older. Over time, cells accumulate damage to their DNA, proteins, and lipids due to various factors such as genetic mutations, oxidative stress, and epigenetic changes. This damage can impair the cell's ability to function properly and can lead to changes associated with aging, such as decreased tissue repair and regeneration, increased inflammation, and increased risk of age-related diseases.

Cellular aging is characterized by several features, including:

1. Shortened telomeres: Telomeres are the protective caps on the ends of chromosomes that shorten each time a cell divides. When telomeres become too short, the cell can no longer divide and becomes senescent or dies.
2. Epigenetic changes: Epigenetic modifications refer to chemical changes to DNA and histone proteins that affect gene expression without changing the underlying genetic code. As cells age, they accumulate epigenetic changes that can alter gene expression and contribute to cellular aging.
3. Oxidative stress: Reactive oxygen species (ROS) are byproducts of cellular metabolism that can damage DNA, proteins, and lipids. Accumulated ROS over time can lead to oxidative stress, which is associated with cellular aging.
4. Inflammation: Senescent cells produce pro-inflammatory cytokines, chemokines, and matrix metalloproteinases that contribute to a low-grade inflammation known as inflammaging. This chronic inflammation can lead to tissue damage and increase the risk of age-related diseases.
5. Genomic instability: DNA damage accumulates with age, leading to genomic instability and an increased risk of mutations and cancer.

Understanding cellular aging is crucial for developing interventions that can delay or prevent age-related diseases and improve healthy lifespan.

Phosphoric diester hydrolases are a class of enzymes that catalyze the hydrolysis of phosphoric diester bonds. These enzymes are also known as phosphatases or nucleotidases. They play important roles in various biological processes, such as signal transduction, metabolism, and regulation of cellular activities.

Phosphoric diester hydrolases can be further classified into several subclasses based on their substrate specificity and catalytic mechanism. For example, alkaline phosphatases (ALPs) are a group of phosphoric diester hydrolases that preferentially hydrolyze phosphomonoester bonds in a variety of organic molecules, releasing phosphate ions and alcohols. On the other hand, nucleotidases are a subclass of phosphoric diester hydrolases that specifically hydrolyze the phosphodiester bonds in nucleotides, releasing nucleosides and phosphate ions.

Overall, phosphoric diester hydrolases are essential for maintaining the balance of various cellular processes by regulating the levels of phosphorylated molecules and nucleotides.

Chromosome mapping, also known as physical mapping, is the process of determining the location and order of specific genes or genetic markers on a chromosome. This is typically done by using various laboratory techniques to identify landmarks along the chromosome, such as restriction enzyme cutting sites or patterns of DNA sequence repeats. The resulting map provides important information about the organization and structure of the genome, and can be used for a variety of purposes, including identifying the location of genes associated with genetic diseases, studying evolutionary relationships between organisms, and developing genetic markers for use in breeding or forensic applications.

Genetic transcription is the process by which the information in a strand of DNA is used to create a complementary RNA molecule. This process is the first step in gene expression, where the genetic code in DNA is converted into a form that can be used to produce proteins or functional RNAs.

During transcription, an enzyme called RNA polymerase binds to the DNA template strand and reads the sequence of nucleotide bases. As it moves along the template, it adds complementary RNA nucleotides to the growing RNA chain, creating a single-stranded RNA molecule that is complementary to the DNA template strand. Once transcription is complete, the RNA molecule may undergo further processing before it can be translated into protein or perform its functional role in the cell.

Transcription can be either "constitutive" or "regulated." Constitutive transcription occurs at a relatively constant rate and produces essential proteins that are required for basic cellular functions. Regulated transcription, on the other hand, is subject to control by various intracellular and extracellular signals, allowing cells to respond to changing environmental conditions or developmental cues.

Substrate specificity in the context of medical biochemistry and enzymology refers to the ability of an enzyme to selectively bind and catalyze a chemical reaction with a particular substrate (or a group of similar substrates) while discriminating against other molecules that are not substrates. This specificity arises from the three-dimensional structure of the enzyme, which has evolved to match the shape, charge distribution, and functional groups of its physiological substrate(s).

Substrate specificity is a fundamental property of enzymes that enables them to carry out highly selective chemical transformations in the complex cellular environment. The active site of an enzyme, where the catalysis takes place, has a unique conformation that complements the shape and charge distribution of its substrate(s). This ensures efficient recognition, binding, and conversion of the substrate into the desired product while minimizing unwanted side reactions with other molecules.

Substrate specificity can be categorized as:

1. Absolute specificity: An enzyme that can only act on a single substrate or a very narrow group of structurally related substrates, showing no activity towards any other molecule.
2. Group specificity: An enzyme that prefers to act on a particular functional group or class of compounds but can still accommodate minor structural variations within the substrate.
3. Broad or promiscuous specificity: An enzyme that can act on a wide range of structurally diverse substrates, albeit with varying catalytic efficiencies.

Understanding substrate specificity is crucial for elucidating enzymatic mechanisms, designing drugs that target specific enzymes or pathways, and developing biotechnological applications that rely on the controlled manipulation of enzyme activities.

Oxidative stress is defined as an imbalance between the production of reactive oxygen species (free radicals) and the body's ability to detoxify them or repair the damage they cause. This imbalance can lead to cellular damage, oxidation of proteins, lipids, and DNA, disruption of cellular functions, and activation of inflammatory responses. Prolonged or excessive oxidative stress has been linked to various health conditions, including cancer, cardiovascular diseases, neurodegenerative disorders, and aging-related diseases.

Oligodeoxyribonucleotides (ODNs) are relatively short, synthetic single-stranded DNA molecules. They typically contain 15 to 30 nucleotides, but can range from 2 to several hundred nucleotides in length. ODNs are often used as tools in molecular biology research for various applications such as:

1. Nucleic acid detection and quantification (e.g., real-time PCR)
2. Gene regulation (antisense, RNA interference)
3. Gene editing (CRISPR-Cas systems)
4. Vaccine development
5. Diagnostic purposes

Due to their specificity and affinity towards complementary DNA or RNA sequences, ODNs can be designed to target a particular gene or sequence of interest. This makes them valuable tools in understanding gene function, regulation, and interaction with other molecules within the cell.

Insertional mutagenesis is a process of introducing new genetic material into an organism's genome at a specific location, which can result in a change or disruption of the function of the gene at that site. This technique is often used in molecular biology research to study gene function and regulation. The introduction of the foreign DNA is typically accomplished through the use of mobile genetic elements, such as transposons or viruses, which are capable of inserting themselves into the genome.

The insertion of the new genetic material can lead to a loss or gain of function in the affected gene, resulting in a mutation. This type of mutagenesis is called "insertional" because the mutation is caused by the insertion of foreign DNA into the genome. The effects of insertional mutagenesis can range from subtle changes in gene expression to the complete inactivation of a gene.

This technique has been widely used in genetic research, including the study of developmental biology, cancer, and genetic diseases. It is also used in the development of genetically modified organisms (GMOs) for agricultural and industrial applications.

RNA interference (RNAi) is a biological process in which RNA molecules inhibit the expression of specific genes. This process is mediated by small RNA molecules, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), that bind to complementary sequences on messenger RNA (mRNA) molecules, leading to their degradation or translation inhibition.

RNAi plays a crucial role in regulating gene expression and defending against foreign genetic elements, such as viruses and transposons. It has also emerged as an important tool for studying gene function and developing therapeutic strategies for various diseases, including cancer and viral infections.

Drug resistance, also known as antimicrobial resistance, is the ability of a microorganism (such as bacteria, viruses, fungi, or parasites) to withstand the effects of a drug that was originally designed to inhibit or kill it. This occurs when the microorganism undergoes genetic changes that allow it to survive in the presence of the drug. As a result, the drug becomes less effective or even completely ineffective at treating infections caused by these resistant organisms.

Drug resistance can develop through various mechanisms, including mutations in the genes responsible for producing the target protein of the drug, alteration of the drug's target site, modification or destruction of the drug by enzymes produced by the microorganism, and active efflux of the drug from the cell.

The emergence and spread of drug-resistant microorganisms pose significant challenges in medical treatment, as they can lead to increased morbidity, mortality, and healthcare costs. The overuse and misuse of antimicrobial agents, as well as poor infection control practices, contribute to the development and dissemination of drug-resistant strains. To address this issue, it is crucial to promote prudent use of antimicrobials, enhance surveillance and monitoring of resistance patterns, invest in research and development of new antimicrobial agents, and strengthen infection prevention and control measures.

Carrier proteins, also known as transport proteins, are a type of protein that facilitates the movement of molecules across cell membranes. They are responsible for the selective and active transport of ions, sugars, amino acids, and other molecules from one side of the membrane to the other, against their concentration gradient. This process requires energy, usually in the form of ATP (adenosine triphosphate).

Carrier proteins have a specific binding site for the molecule they transport, and undergo conformational changes upon binding, which allows them to move the molecule across the membrane. Once the molecule has been transported, the carrier protein returns to its original conformation, ready to bind and transport another molecule.

Carrier proteins play a crucial role in maintaining the balance of ions and other molecules inside and outside of cells, and are essential for many physiological processes, including nerve impulse transmission, muscle contraction, and nutrient uptake.

An allele is a variant form of a gene that is located at a specific position on a specific chromosome. Alleles are alternative forms of the same gene that arise by mutation and are found at the same locus or position on homologous chromosomes.

Each person typically inherits two copies of each gene, one from each parent. If the two alleles are identical, a person is said to be homozygous for that trait. If the alleles are different, the person is heterozygous.

For example, the ABO blood group system has three alleles, A, B, and O, which determine a person's blood type. If a person inherits two A alleles, they will have type A blood; if they inherit one A and one B allele, they will have type AB blood; if they inherit two B alleles, they will have type B blood; and if they inherit two O alleles, they will have type O blood.

Alleles can also influence traits such as eye color, hair color, height, and other physical characteristics. Some alleles are dominant, meaning that only one copy of the allele is needed to express the trait, while others are recessive, meaning that two copies of the allele are needed to express the trait.

A phenotype is the physical or biochemical expression of an organism's genes, or the observable traits and characteristics resulting from the interaction of its genetic constitution (genotype) with environmental factors. These characteristics can include appearance, development, behavior, and resistance to disease, among others. Phenotypes can vary widely, even among individuals with identical genotypes, due to differences in environmental influences, gene expression, and genetic interactions.

Temperature, in a medical context, is a measure of the degree of hotness or coldness of a body or environment. It is usually measured using a thermometer and reported in degrees Celsius (°C), degrees Fahrenheit (°F), or kelvin (K). In the human body, normal core temperature ranges from about 36.5-37.5°C (97.7-99.5°F) when measured rectally, and can vary slightly depending on factors such as time of day, physical activity, and menstrual cycle. Elevated body temperature is a common sign of infection or inflammation, while abnormally low body temperature can indicate hypothermia or other medical conditions.

Germ cells are the reproductive cells, also known as sex cells, that combine to form offspring in sexual reproduction. In females, germ cells are called ova or egg cells, and in males, they are called spermatozoa or sperm cells. These cells are unique because they carry half the genetic material necessary for creating new life. They are produced through a process called meiosis, which reduces their chromosome number by half, ensuring that when two germ cells combine during fertilization, the normal diploid number of chromosomes is restored.

"T-lymphocyte gene rearrangement" refers to the process that occurs during the development of T-cells (a type of white blood cell) in which the genes that code for their antigen receptors are rearranged to create a unique receptor that can recognize and bind to specific foreign molecules, such as viruses or tumor cells.

The T-cell receptor (TCR) is made up of two chains, alpha and beta, which are composed of variable and constant regions. During gene rearrangement, the variable region genes are rearranged through a process called V(D)J recombination, in which specific segments of DNA are cut and joined together to form a unique combination that encodes for a diverse range of antigen receptors.

This allows T-cells to recognize and respond to a wide variety of foreign molecules, contributing to the adaptive immune response. However, this process can also lead to errors and the generation of T-cells with self-reactive receptors, which can contribute to autoimmune diseases if not properly regulated.

Sodium Chloride is defined as the inorganic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is commonly known as table salt or halite, and it is used extensively in food seasoning and preservation due to its ability to enhance flavor and inhibit bacterial growth. In medicine, sodium chloride is used as a balanced electrolyte solution for rehydration and as a topical wound irrigant and antiseptic. It is also an essential component of the human body's fluid balance and nerve impulse transmission.

Polynucleotide 5'-Hydroxyl-Kinase (PNK) is an enzyme that catalyzes the addition of a phosphate group to the 5'-hydroxyl end of a polynucleotide strand, such as DNA or RNA. This enzyme plays a crucial role in the repair and maintenance of DNA ends during various cellular processes, including DNA replication, recombination, and repair.

PNK has two distinct activities: 5'-kinase activity and 3'-phosphatase activity. The 5'-kinase activity adds a phosphate group to the 5'-hydroxyl end of a polynucleotide strand, while the 3'-phosphatase activity removes a phosphate group from the 3'-end of a strand. These activities enable PNK to process and repair DNA ends with missing or damaged phosphate groups, ensuring their proper alignment and ligation during DNA repair and recombination.

PNK is involved in several essential cellular pathways, including base excision repair (BER), nucleotide excision repair (NER), and double-strand break (DSB) repair. Dysregulation or mutations in PNK can lead to genomic instability and contribute to the development of various diseases, such as cancer and neurodegenerative disorders.

Ubiquitin-protein ligases, also known as E3 ubiquitin ligases, are a group of enzymes that play a crucial role in the ubiquitination process. Ubiquitination is a post-translational modification where ubiquitin molecules are attached to specific target proteins, marking them for degradation by the proteasome or for other regulatory functions.

Ubiquitin-protein ligases catalyze the final step in this process by binding to both the ubiquitin protein and the target protein, facilitating the transfer of ubiquitin from an E2 ubiquitin-conjugating enzyme to the target protein. There are several different types of ubiquitin-protein ligases, each with their own specificity for particular target proteins and regulatory functions.

Ubiquitin-protein ligases have been implicated in various cellular processes such as protein degradation, DNA repair, signal transduction, and regulation of the cell cycle. Dysregulation of ubiquitination has been associated with several diseases, including cancer, neurodegenerative disorders, and inflammatory responses. Therefore, understanding the function and regulation of ubiquitin-protein ligases is an important area of research in biology and medicine.

C57BL/6 (C57 Black 6) is an inbred strain of laboratory mouse that is widely used in biomedical research. The term "inbred" refers to a strain of animals where matings have been carried out between siblings or other closely related individuals for many generations, resulting in a population that is highly homozygous at most genetic loci.

The C57BL/6 strain was established in 1920 by crossing a female mouse from the dilute brown (DBA) strain with a male mouse from the black strain. The resulting offspring were then interbred for many generations to create the inbred C57BL/6 strain.

C57BL/6 mice are known for their robust health, longevity, and ease of handling, making them a popular choice for researchers. They have been used in a wide range of biomedical research areas, including studies of cancer, immunology, neuroscience, cardiovascular disease, and metabolism.

One of the most notable features of the C57BL/6 strain is its sensitivity to certain genetic modifications, such as the introduction of mutations that lead to obesity or impaired glucose tolerance. This has made it a valuable tool for studying the genetic basis of complex diseases and traits.

Overall, the C57BL/6 inbred mouse strain is an important model organism in biomedical research, providing a valuable resource for understanding the genetic and molecular mechanisms underlying human health and disease.

Reactive Oxygen Species (ROS) are highly reactive molecules containing oxygen, including peroxides, superoxide, hydroxyl radical, and singlet oxygen. They are naturally produced as byproducts of normal cellular metabolism in the mitochondria, and can also be generated by external sources such as ionizing radiation, tobacco smoke, and air pollutants. At low or moderate concentrations, ROS play important roles in cell signaling and homeostasis, but at high concentrations, they can cause significant damage to cell structures, including lipids, proteins, and DNA, leading to oxidative stress and potential cell death.

'Drosophila melanogaster' is the scientific name for a species of fruit fly that is commonly used as a model organism in various fields of biological research, including genetics, developmental biology, and evolutionary biology. Its small size, short generation time, large number of offspring, and ease of cultivation make it an ideal subject for laboratory studies. The fruit fly's genome has been fully sequenced, and many of its genes have counterparts in the human genome, which facilitates the understanding of genetic mechanisms and their role in human health and disease.

Here is a brief medical definition:

Drosophila melanogaster (droh-suh-fih-luh meh-lon-guh-ster): A species of fruit fly used extensively as a model organism in genetic, developmental, and evolutionary research. Its genome has been sequenced, revealing many genes with human counterparts, making it valuable for understanding genetic mechanisms and their role in human health and disease.

DNA transposable elements, also known as transposons or jumping genes, are mobile genetic elements that can change their position within a genome. They are composed of DNA sequences that include genes encoding the enzymes required for their own movement (transposase) and regulatory elements. When activated, the transposase recognizes specific sequences at the ends of the element and catalyzes the excision and reintegration of the transposable element into a new location in the genome. This process can lead to genetic variation, as the insertion of a transposable element can disrupt the function of nearby genes or create new combinations of gene regulatory elements. Transposable elements are widespread in both prokaryotic and eukaryotic genomes and are thought to play a significant role in genome evolution.

Retinal detachment is a serious eye condition that occurs when the retina, a thin layer of tissue at the back of the eye responsible for processing light and sending visual signals to the brain, pulls away from its normal position. This can lead to significant vision loss or even blindness if not promptly treated. Retinal detachment can be caused by various factors such as aging, trauma, eye disease, or an inflammatory condition. Symptoms of retinal detachment may include sudden flashes of light, floaters, a shadow in the peripheral vision, or a curtain-like covering over part of the visual field. Immediate medical attention is necessary to prevent further damage and preserve vision.

Spermatozoa are the male reproductive cells, or gametes, that are produced in the testes. They are microscopic, flagellated (tail-equipped) cells that are highly specialized for fertilization. A spermatozoon consists of a head, neck, and tail. The head contains the genetic material within the nucleus, covered by a cap-like structure called the acrosome which contains enzymes to help the sperm penetrate the female's egg (ovum). The long, thin tail propels the sperm forward through fluid, such as semen, enabling its journey towards the egg for fertilization.

The thymus gland is an essential organ of the immune system, located in the upper chest, behind the sternum and surrounding the heart. It's primarily active until puberty and begins to shrink in size and activity thereafter. The main function of the thymus gland is the production and maturation of T-lymphocytes (T-cells), which are crucial for cell-mediated immunity, helping to protect the body from infection and cancer.

The thymus gland provides a protected environment where immune cells called pre-T cells develop into mature T cells. During this process, they learn to recognize and respond appropriately to foreign substances while remaining tolerant to self-tissues, which is crucial for preventing autoimmune diseases.

Additionally, the thymus gland produces hormones like thymosin that regulate immune cell activities and contribute to the overall immune response.

Transcription factors are proteins that play a crucial role in regulating gene expression by controlling the transcription of DNA to messenger RNA (mRNA). They function by binding to specific DNA sequences, known as response elements, located in the promoter region or enhancer regions of target genes. This binding can either activate or repress the initiation of transcription, depending on the properties and interactions of the particular transcription factor. Transcription factors often act as part of a complex network of regulatory proteins that determine the precise spatiotemporal patterns of gene expression during development, differentiation, and homeostasis in an organism.

Transfection is a term used in molecular biology that refers to the process of deliberately introducing foreign genetic material (DNA, RNA or artificial gene constructs) into cells. This is typically done using chemical or physical methods, such as lipofection or electroporation. Transfection is widely used in research and medical settings for various purposes, including studying gene function, producing proteins, developing gene therapies, and creating genetically modified organisms. It's important to note that transfection is different from transduction, which is the process of introducing genetic material into cells using viruses as vectors.

A sequence deletion in a genetic context refers to the removal or absence of one or more nucleotides (the building blocks of DNA or RNA) from a specific region in a DNA or RNA molecule. This type of mutation can lead to the loss of genetic information, potentially resulting in changes in the function or expression of a gene. If the deletion involves a critical portion of the gene, it can cause diseases, depending on the role of that gene in the body. The size of the deleted sequence can vary, ranging from a single nucleotide to a large segment of DNA.

DNA Sequence Analysis is the systematic determination of the order of nucleotides in a DNA molecule. It is a critical component of modern molecular biology, genetics, and genetic engineering. The process involves determining the exact order of the four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - in a DNA molecule or fragment. This information is used in various applications such as identifying gene mutations, studying evolutionary relationships, developing molecular markers for breeding, and diagnosing genetic diseases.

The process of DNA Sequence Analysis typically involves several steps, including DNA extraction, PCR amplification (if necessary), purification, sequencing reaction, and electrophoresis. The resulting data is then analyzed using specialized software to determine the exact sequence of nucleotides.

In recent years, high-throughput DNA sequencing technologies have revolutionized the field of genomics, enabling the rapid and cost-effective sequencing of entire genomes. This has led to an explosion of genomic data and new insights into the genetic basis of many diseases and traits.

Drug screening assays for antitumor agents are laboratory tests used to identify and evaluate the effectiveness of potential drugs or compounds that can inhibit the growth of tumor cells or induce their death. These assays are typically performed in vitro (in a test tube or petri dish) using cell cultures of various types of cancer cells.

The assays measure different parameters such as cell viability, proliferation, apoptosis (programmed cell death), and cytotoxicity to determine the ability of the drug to kill or inhibit the growth of tumor cells. The results of these assays can help researchers identify promising antitumor agents that can be further developed for clinical use in cancer treatment.

There are different types of drug screening assays for antitumor agents, including high-throughput screening (HTS) assays, which allow for the rapid and automated testing of a large number of compounds against various cancer cell lines. Other types of assays include phenotypic screening assays, target-based screening assays, and functional screening assays, each with its own advantages and limitations.

Overall, drug screening assays for antitumor agents play a critical role in the development of new cancer therapies by providing valuable information on the activity and safety of potential drugs, helping to identify effective treatments and reduce the time and cost associated with bringing new drugs to market.

'Gene expression regulation' refers to the processes that control whether, when, and where a particular gene is expressed, meaning the production of a specific protein or functional RNA encoded by that gene. This complex mechanism can be influenced by various factors such as transcription factors, chromatin remodeling, DNA methylation, non-coding RNAs, and post-transcriptional modifications, among others. Proper regulation of gene expression is crucial for normal cellular function, development, and maintaining homeostasis in living organisms. Dysregulation of gene expression can lead to various diseases, including cancer and genetic disorders.

A heterozygote is an individual who has inherited two different alleles (versions) of a particular gene, one from each parent. This means that the individual's genotype for that gene contains both a dominant and a recessive allele. The dominant allele will be expressed phenotypically (outwardly visible), while the recessive allele may or may not have any effect on the individual's observable traits, depending on the specific gene and its function. Heterozygotes are often represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.

Glycolates are a type of chemical compound that contain the group COOCH2, which is derived from glycolic acid. In a medical context, glycolates are often used in dental and medical materials as they can be biodegradable and biocompatible. For example, they may be used in controlled-release drug delivery systems or in bone cement. However, it's important to note that some glycolate compounds can also be toxic if ingested or otherwise introduced into the body in large amounts.

Chromatin Immunoprecipitation (ChIP) is a molecular biology technique used to analyze the interaction between proteins and DNA in the cell. It is a powerful tool for studying protein-DNA binding, such as transcription factor binding to specific DNA sequences, histone modification, and chromatin structure.

In ChIP assays, cells are first crosslinked with formaldehyde to preserve protein-DNA interactions. The chromatin is then fragmented into small pieces using sonication or other methods. Specific antibodies against the protein of interest are added to precipitate the protein-DNA complexes. After reversing the crosslinking, the DNA associated with the protein is purified and analyzed using PCR, sequencing, or microarray technologies.

ChIP assays can provide valuable information about the regulation of gene expression, epigenetic modifications, and chromatin structure in various biological processes and diseases, including cancer, development, and differentiation.

A genetic complementation test is a laboratory procedure used in molecular genetics to determine whether two mutated genes can complement each other's function, indicating that they are located at different loci and represent separate alleles. This test involves introducing a normal or wild-type copy of one gene into a cell containing a mutant version of the same gene, and then observing whether the presence of the normal gene restores the normal function of the mutated gene. If the introduction of the normal gene results in the restoration of the normal phenotype, it suggests that the two genes are located at different loci and can complement each other's function. However, if the introduction of the normal gene does not restore the normal phenotype, it suggests that the two genes are located at the same locus and represent different alleles of the same gene. This test is commonly used to map genes and identify genetic interactions in a variety of organisms, including bacteria, yeast, and animals.

A cell-free system is a biochemical environment in which biological reactions can occur outside of an intact living cell. These systems are often used to study specific cellular processes or pathways, as they allow researchers to control and manipulate the conditions in which the reactions take place. In a cell-free system, the necessary enzymes, substrates, and cofactors for a particular reaction are provided in a test tube or other container, rather than within a whole cell.

Cell-free systems can be derived from various sources, including bacteria, yeast, and mammalian cells. They can be used to study a wide range of cellular processes, such as transcription, translation, protein folding, and metabolism. For example, a cell-free system might be used to express and purify a specific protein, or to investigate the regulation of a particular metabolic pathway.

One advantage of using cell-free systems is that they can provide valuable insights into the mechanisms of cellular processes without the need for time-consuming and resource-intensive cell culture or genetic manipulation. Additionally, because cell-free systems are not constrained by the limitations of a whole cell, they offer greater flexibility in terms of reaction conditions and the ability to study complex or transient interactions between biological molecules.

Overall, cell-free systems are an important tool in molecular biology and biochemistry, providing researchers with a versatile and powerful means of investigating the fundamental processes that underlie life at the cellular level.

The synaptonemal complex is a protein structure that forms between two homologous chromosomes during meiosis, the type of cell division that leads to the production of gametes (sex cells). The synaptonemal complex consists of two lateral elements, which are associated with each of the homologous chromosomes, and a central element that runs parallel to the length of the complex and connects the two lateral elements.

The synaptonemal complex plays a crucial role in the process of genetic recombination, which occurs during meiosis. Genetic recombination is the exchange of genetic material between two homologous chromosomes that results in new combinations of genes on the chromosomes. This process helps to increase genetic diversity and is essential for the proper segregation of chromosomes during meiosis.

The synaptonemal complex also helps to ensure that the correct number of chromosomes are distributed to each gamete by holding the homologous chromosomes together until they can be properly aligned and separated during meiosis. Mutations in genes involved in the formation and maintenance of the synaptonemal complex can lead to fertility problems, developmental abnormalities, and other genetic disorders.

Dimerization is a process in which two molecules, usually proteins or similar structures, bind together to form a larger complex. This can occur through various mechanisms, such as the formation of disulfide bonds, hydrogen bonding, or other non-covalent interactions. Dimerization can play important roles in cell signaling, enzyme function, and the regulation of gene expression.

In the context of medical research and therapy, dimerization is often studied in relation to specific proteins that are involved in diseases such as cancer. For example, some drugs have been developed to target and inhibit the dimerization of certain proteins, with the goal of disrupting their function and slowing or stopping the progression of the disease.

Cell proliferation is the process by which cells increase in number, typically through the process of cell division. In the context of biology and medicine, it refers to the reproduction of cells that makes up living tissue, allowing growth, maintenance, and repair. It involves several stages including the transition from a phase of quiescence (G0 phase) to an active phase (G1 phase), DNA replication in the S phase, and mitosis or M phase, where the cell divides into two daughter cells.

Abnormal or uncontrolled cell proliferation is a characteristic feature of many diseases, including cancer, where deregulated cell cycle control leads to excessive and unregulated growth of cells, forming tumors that can invade surrounding tissues and metastasize to distant sites in the body.

Caspases are a family of protease enzymes that play essential roles in programmed cell death, also known as apoptosis. These enzymes are produced as inactive precursors and are activated when cells receive signals to undergo apoptosis. Once activated, caspases cleave specific protein substrates, leading to the characteristic morphological changes and DNA fragmentation associated with apoptotic cell death. Caspases also play roles in other cellular processes, including inflammation and differentiation. There are two types of caspases: initiator caspases (caspase-2, -8, -9, and -10) and effector caspases (caspase-3, -6, and -7). Initiator caspases are activated in response to various apoptotic signals and then activate the effector caspases, which carry out the proteolytic cleavage of cellular proteins. Dysregulation of caspase activity has been implicated in a variety of diseases, including neurodegenerative disorders, ischemic injury, and cancer.

Benzamides are a class of organic compounds that consist of a benzene ring (a aromatic hydrocarbon) attached to an amide functional group. The amide group can be bound to various substituents, leading to a variety of benzamide derivatives with different biological activities.

In a medical context, some benzamides have been developed as drugs for the treatment of various conditions. For example, danzol (a benzamide derivative) is used as a hormonal therapy for endometriosis and breast cancer. Additionally, other benzamides such as sulpiride and amisulpride are used as antipsychotic medications for the treatment of schizophrenia and related disorders.

It's important to note that while some benzamides have therapeutic uses, others may be toxic or have adverse effects, so they should only be used under the supervision of a medical professional.

Adenosine Triphosphate (ATP) is a high-energy molecule that stores and transports energy within cells. It is the main source of energy for most cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis. ATP is composed of a base (adenine), a sugar (ribose), and three phosphate groups. The bonds between these phosphate groups contain a significant amount of energy, which can be released when the bond between the second and third phosphate group is broken, resulting in the formation of adenosine diphosphate (ADP) and inorganic phosphate. This process is known as hydrolysis and can be catalyzed by various enzymes to drive a wide range of cellular functions. ATP can also be regenerated from ADP through various metabolic pathways, such as oxidative phosphorylation or substrate-level phosphorylation, allowing for the continuous supply of energy to cells.

Sequence homology in nucleic acids refers to the similarity or identity between the nucleotide sequences of two or more DNA or RNA molecules. It is often used as a measure of biological relationship between genes, organisms, or populations. High sequence homology suggests a recent common ancestry or functional constraint, while low sequence homology may indicate a more distant relationship or different functions.

Nucleic acid sequence homology can be determined by various methods such as pairwise alignment, multiple sequence alignment, and statistical analysis. The degree of homology is typically expressed as a percentage of identical or similar nucleotides in a given window of comparison.

It's important to note that the interpretation of sequence homology depends on the biological context and the evolutionary distance between the sequences compared. Therefore, functional and experimental validation is often necessary to confirm the significance of sequence homology.

I'm sorry for any confusion, but "Holidays" is a term that generally refers to days of celebration or observance that are often recognized by society, cultures, or religions. It does not have a specific medical definition. If you have any medical concerns or questions, I would be happy to try and help answer those for you.

Viral DNA refers to the genetic material present in viruses that consist of DNA as their core component. Deoxyribonucleic acid (DNA) is one of the two types of nucleic acids that are responsible for storing and transmitting genetic information in living organisms. Viruses are infectious agents much smaller than bacteria that can only replicate inside the cells of other organisms, called hosts.

Viral DNA can be double-stranded (dsDNA) or single-stranded (ssDNA), depending on the type of virus. Double-stranded DNA viruses have a genome made up of two complementary strands of DNA, while single-stranded DNA viruses contain only one strand of DNA.

Examples of dsDNA viruses include Adenoviruses, Herpesviruses, and Poxviruses, while ssDNA viruses include Parvoviruses and Circoviruses. Viral DNA plays a crucial role in the replication cycle of the virus, encoding for various proteins necessary for its multiplication and survival within the host cell.

A retinal perforation is a full-thickness break or hole in the retina, which is the light-sensitive tissue that lines the inner surface of the eye. This condition can lead to a serious complication called retinal detachment, where the retina separates from the underlying tissue, potentially resulting in vision loss if not promptly treated. Retinal perforations may be caused by trauma, certain eye conditions, or invasive eye procedures. Immediate medical attention is required for retinal perforations to prevent further damage and preserve vision.

Homeodomain proteins are a group of transcription factors that play crucial roles in the development and differentiation of cells in animals and plants. They are characterized by the presence of a highly conserved DNA-binding domain called the homeodomain, which is typically about 60 amino acids long. The homeodomain consists of three helices, with the third helix responsible for recognizing and binding to specific DNA sequences.

Homeodomain proteins are involved in regulating gene expression during embryonic development, tissue maintenance, and organismal growth. They can act as activators or repressors of transcription, depending on the context and the presence of cofactors. Mutations in homeodomain proteins have been associated with various human diseases, including cancer, congenital abnormalities, and neurological disorders.

Some examples of homeodomain proteins include PAX6, which is essential for eye development, HOX genes, which are involved in body patterning, and NANOG, which plays a role in maintaining pluripotency in stem cells.

'Caenorhabditis elegans' is a species of free-living, transparent nematode (roundworm) that is widely used as a model organism in scientific research, particularly in the fields of biology and genetics. It has a simple anatomy, short lifespan, and fully sequenced genome, making it an ideal subject for studying various biological processes and diseases.

Some notable features of C. elegans include:

* Small size: Adult hermaphrodites are about 1 mm in length.
* Short lifespan: The average lifespan of C. elegans is around 2-3 weeks, although some strains can live up to 4 weeks under laboratory conditions.
* Development: C. elegans has a well-characterized developmental process, with adults developing from eggs in just 3 days at 20°C.
* Transparency: The transparent body of C. elegans allows researchers to observe its internal structures and processes easily.
* Genetics: C. elegans has a fully sequenced genome, which contains approximately 20,000 genes. Many of these genes have human homologs, making it an excellent model for studying human diseases.
* Neurobiology: C. elegans has a simple nervous system, with only 302 neurons in the hermaphrodite and 383 in the male. This simplicity makes it an ideal organism for studying neural development, function, and behavior.

Research using C. elegans has contributed significantly to our understanding of various biological processes, including cell division, apoptosis, aging, learning, and memory. Additionally, studies on C. elegans have led to the discovery of many genes associated with human diseases such as cancer, neurodegenerative disorders, and metabolic conditions.

Meiotic Prophase I is a stage in the meiotic division of cellular reproduction that results in the formation of gametes or sex cells (sperm and egg). It is the first of five stages in Meiosis I, which is a type of cell division that reduces the chromosome number by half.

During Meiotic Prophase I, homologous chromosomes pair and form tetrads (four-stranded structures), which then undergo genetic recombination or crossing over, resulting in new combinations of alleles on the chromatids of each homologous chromosome. This stage can be further divided into several substages: leptonema, zygonema, pachynema, diplonema, and diakinesis. These substages are characterized by distinct changes in chromosome structure and behavior, including the condensation and movement of the chromosomes, as well as the formation and dissolution of the synaptonemal complex, a protein structure that holds the homologous chromosomes together during crossing over.

Overall, Meiotic Prophase I is a critical stage in meiosis that ensures genetic diversity in offspring by shuffling the genetic material between homologous chromosomes and creating new combinations of alleles.

Molecular models are three-dimensional representations of molecular structures that are used in the field of molecular biology and chemistry to visualize and understand the spatial arrangement of atoms and bonds within a molecule. These models can be physical or computer-generated and allow researchers to study the shape, size, and behavior of molecules, which is crucial for understanding their function and interactions with other molecules.

Physical molecular models are often made up of balls (representing atoms) connected by rods or sticks (representing bonds). These models can be constructed manually using materials such as plastic or wooden balls and rods, or they can be created using 3D printing technology.

Computer-generated molecular models, on the other hand, are created using specialized software that allows researchers to visualize and manipulate molecular structures in three dimensions. These models can be used to simulate molecular interactions, predict molecular behavior, and design new drugs or chemicals with specific properties. Overall, molecular models play a critical role in advancing our understanding of molecular structures and their functions.

Recombinant proteins are artificially created proteins produced through the use of recombinant DNA technology. This process involves combining DNA molecules from different sources to create a new set of genes that encode for a specific protein. The resulting recombinant protein can then be expressed, purified, and used for various applications in research, medicine, and industry.

Recombinant proteins are widely used in biomedical research to study protein function, structure, and interactions. They are also used in the development of diagnostic tests, vaccines, and therapeutic drugs. For example, recombinant insulin is a common treatment for diabetes, while recombinant human growth hormone is used to treat growth disorders.

The production of recombinant proteins typically involves the use of host cells, such as bacteria, yeast, or mammalian cells, which are engineered to express the desired protein. The host cells are transformed with a plasmid vector containing the gene of interest, along with regulatory elements that control its expression. Once the host cells are cultured and the protein is expressed, it can be purified using various chromatography techniques.

Overall, recombinant proteins have revolutionized many areas of biology and medicine, enabling researchers to study and manipulate proteins in ways that were previously impossible.

Immunoblotting, also known as western blotting, is a laboratory technique used in molecular biology and immunogenetics to detect and quantify specific proteins in a complex mixture. This technique combines the electrophoretic separation of proteins by gel electrophoresis with their detection using antibodies that recognize specific epitopes (protein fragments) on the target protein.

The process involves several steps: first, the protein sample is separated based on size through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Next, the separated proteins are transferred onto a nitrocellulose or polyvinylidene fluoride (PVDF) membrane using an electric field. The membrane is then blocked with a blocking agent to prevent non-specific binding of antibodies.

After blocking, the membrane is incubated with a primary antibody that specifically recognizes the target protein. Following this, the membrane is washed to remove unbound primary antibodies and then incubated with a secondary antibody conjugated to an enzyme such as horseradish peroxidase (HRP) or alkaline phosphatase (AP). The enzyme catalyzes a colorimetric or chemiluminescent reaction that allows for the detection of the target protein.

Immunoblotting is widely used in research and clinical settings to study protein expression, post-translational modifications, protein-protein interactions, and disease biomarkers. It provides high specificity and sensitivity, making it a valuable tool for identifying and quantifying proteins in various biological samples.

Transgenic mice are genetically modified rodents that have incorporated foreign DNA (exogenous DNA) into their own genome. This is typically done through the use of recombinant DNA technology, where a specific gene or genetic sequence of interest is isolated and then introduced into the mouse embryo. The resulting transgenic mice can then express the protein encoded by the foreign gene, allowing researchers to study its function in a living organism.

The process of creating transgenic mice usually involves microinjecting the exogenous DNA into the pronucleus of a fertilized egg, which is then implanted into a surrogate mother. The offspring that result from this procedure are screened for the presence of the foreign DNA, and those that carry the desired genetic modification are used to establish a transgenic mouse line.

Transgenic mice have been widely used in biomedical research to model human diseases, study gene function, and test new therapies. They provide a valuable tool for understanding complex biological processes and developing new treatments for a variety of medical conditions.

Sequence homology, amino acid, refers to the similarity in the order of amino acids in a protein or a portion of a protein between two or more species. This similarity can be used to infer evolutionary relationships and functional similarities between proteins. The higher the degree of sequence homology, the more likely it is that the proteins are related and have similar functions. Sequence homology can be determined through various methods such as pairwise alignment or multiple sequence alignment, which compare the sequences and calculate a score based on the number and type of matching amino acids.

Restriction mapping is a technique used in molecular biology to identify the location and arrangement of specific restriction endonuclease recognition sites within a DNA molecule. Restriction endonucleases are enzymes that cut double-stranded DNA at specific sequences, producing fragments of various lengths. By digesting the DNA with different combinations of these enzymes and analyzing the resulting fragment sizes through techniques such as agarose gel electrophoresis, researchers can generate a restriction map - a visual representation of the locations and distances between recognition sites on the DNA molecule. This information is crucial for various applications, including cloning, genome analysis, and genetic engineering.

Polymerase Chain Reaction (PCR) is a laboratory technique used to amplify specific regions of DNA. It enables the production of thousands to millions of copies of a particular DNA sequence in a rapid and efficient manner, making it an essential tool in various fields such as molecular biology, medical diagnostics, forensic science, and research.

The PCR process involves repeated cycles of heating and cooling to separate the DNA strands, allow primers (short sequences of single-stranded DNA) to attach to the target regions, and extend these primers using an enzyme called Taq polymerase, resulting in the exponential amplification of the desired DNA segment.

In a medical context, PCR is often used for detecting and quantifying specific pathogens (viruses, bacteria, fungi, or parasites) in clinical samples, identifying genetic mutations or polymorphisms associated with diseases, monitoring disease progression, and evaluating treatment effectiveness.

Bacterial proteins are a type of protein that are produced by bacteria as part of their structural or functional components. These proteins can be involved in various cellular processes, such as metabolism, DNA replication, transcription, and translation. They can also play a role in bacterial pathogenesis, helping the bacteria to evade the host's immune system, acquire nutrients, and multiply within the host.

Bacterial proteins can be classified into different categories based on their function, such as:

1. Enzymes: Proteins that catalyze chemical reactions in the bacterial cell.
2. Structural proteins: Proteins that provide structural support and maintain the shape of the bacterial cell.
3. Signaling proteins: Proteins that help bacteria to communicate with each other and coordinate their behavior.
4. Transport proteins: Proteins that facilitate the movement of molecules across the bacterial cell membrane.
5. Toxins: Proteins that are produced by pathogenic bacteria to damage host cells and promote infection.
6. Surface proteins: Proteins that are located on the surface of the bacterial cell and interact with the environment or host cells.

Understanding the structure and function of bacterial proteins is important for developing new antibiotics, vaccines, and other therapeutic strategies to combat bacterial infections.

DNA topoisomerases are enzymes that play a crucial role in the regulation of DNA topology, which refers to the three-dimensional arrangement of the DNA molecule. These enzymes control the number of twists or coils in the DNA helix by creating temporary breaks in the strands and allowing them to rotate around each other, thereby relieving the torsional stress that builds up during processes such as replication and transcription.

There are two main types of DNA topoisomerases: type I and type II. Type I enzymes create a single-stranded break in the DNA helix, while type II enzymes create a double-stranded break. Both types of enzymes can change the linking number (Lk) of the DNA molecule, which is a topological invariant that describes the overall degree of twist in the helix.

Type I topoisomerases are further divided into two subtypes: type IA and type IB. Type IA enzymes, such as topo I from Escherichia coli, create a transient break in one DNA strand and then pass the other strand through the break before resealing it. In contrast, type IB enzymes, such as human topo I, create a covalent bond with the 3'-phosphate end of the broken strand and then pass the 5'-end through the break before rejoining the ends.

Type II topoisomerases are also divided into two subtypes: type IIA and type IIB. Type IIA enzymes, such as bacterial topo IV and eukaryotic topo II, create a double-stranded break in the DNA helix and then pass another segment of double-stranded DNA through the break before resealing it. Type IIB enzymes, such as bacterial topo III and eukaryotic topo IIIα and β, create a double-stranded break and then pass a single strand of DNA through the break before resealing it.

DNA topoisomerases are important targets for cancer chemotherapy because they are essential for cell division and can be inhibited by drugs such as doxorubicin, etoposide, and irinotecan. However, these drugs can also have significant side effects, including cardiotoxicity and myelosuppression. Therefore, there is ongoing research to develop new topoisomerase inhibitors with improved efficacy and safety profiles.

Adenosine triphosphatases (ATPases) are a group of enzymes that catalyze the conversion of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and inorganic phosphate. This reaction releases energy, which is used to drive various cellular processes such as muscle contraction, transport of ions across membranes, and synthesis of proteins and nucleic acids.

ATPases are classified into several types based on their structure, function, and mechanism of action. Some examples include:

1. P-type ATPases: These ATPases form a phosphorylated intermediate during the reaction cycle and are involved in the transport of ions across membranes, such as the sodium-potassium pump and calcium pumps.
2. F-type ATPases: These ATPases are found in mitochondria, chloroplasts, and bacteria, and are responsible for generating a proton gradient across the membrane, which is used to synthesize ATP.
3. V-type ATPases: These ATPases are found in vacuolar membranes and endomembranes, and are involved in acidification of intracellular compartments.
4. A-type ATPases: These ATPases are found in the plasma membrane and are involved in various functions such as cell signaling and ion transport.

Overall, ATPases play a crucial role in maintaining the energy balance of cells and regulating various physiological processes.

The Fluorescent Antibody Technique (FAT) is a type of immunofluorescence assay used in laboratory medicine and pathology for the detection and localization of specific antigens or antibodies in tissues, cells, or microorganisms. In this technique, a fluorescein-labeled antibody is used to selectively bind to the target antigen or antibody, forming an immune complex. When excited by light of a specific wavelength, the fluorescein label emits light at a longer wavelength, typically visualized as green fluorescence under a fluorescence microscope.

The FAT is widely used in diagnostic microbiology for the identification and characterization of various bacteria, viruses, fungi, and parasites. It has also been applied in the diagnosis of autoimmune diseases and certain cancers by detecting specific antibodies or antigens in patient samples. The main advantage of FAT is its high sensitivity and specificity, allowing for accurate detection and differentiation of various pathogens and disease markers. However, it requires specialized equipment and trained personnel to perform and interpret the results.

Radiation effects refer to the damages that occur in living tissues when exposed to ionizing radiation. These effects can be categorized into two types: deterministic and stochastic. Deterministic effects have a threshold dose below which the effect does not occur, and above which the severity of the effect increases with the dose. Examples include radiation-induced erythema, epilation, and organ damage. Stochastic effects, on the other hand, do not have a threshold dose, and the probability of the effect occurring increases with the dose. Examples include genetic mutations and cancer induction. The severity of the effect is not related to the dose in this case.

Gene expression is the process by which the information encoded in a gene is used to synthesize a functional gene product, such as a protein or RNA molecule. This process involves several steps: transcription, RNA processing, and translation. During transcription, the genetic information in DNA is copied into a complementary RNA molecule, known as messenger RNA (mRNA). The mRNA then undergoes RNA processing, which includes adding a cap and tail to the mRNA and splicing out non-coding regions called introns. The resulting mature mRNA is then translated into a protein on ribosomes in the cytoplasm through the process of translation.

The regulation of gene expression is a complex and highly controlled process that allows cells to respond to changes in their environment, such as growth factors, hormones, and stress signals. This regulation can occur at various stages of gene expression, including transcriptional activation or repression, RNA processing, mRNA stability, and translation. Dysregulation of gene expression has been implicated in many diseases, including cancer, genetic disorders, and neurological conditions.

Proteins are complex, large molecules that play critical roles in the body's functions. They are made up of amino acids, which are organic compounds that are the building blocks of proteins. Proteins are required for the structure, function, and regulation of the body's tissues and organs. They are essential for the growth, repair, and maintenance of body tissues, and they play a crucial role in many biological processes, including metabolism, immune response, and cellular signaling. Proteins can be classified into different types based on their structure and function, such as enzymes, hormones, antibodies, and structural proteins. They are found in various foods, especially animal-derived products like meat, dairy, and eggs, as well as plant-based sources like beans, nuts, and grains.

Breast neoplasms refer to abnormal growths in the breast tissue that can be benign or malignant. Benign breast neoplasms are non-cancerous tumors or growths, while malignant breast neoplasms are cancerous tumors that can invade surrounding tissues and spread to other parts of the body.

Breast neoplasms can arise from different types of cells in the breast, including milk ducts, milk sacs (lobules), or connective tissue. The most common type of breast cancer is ductal carcinoma, which starts in the milk ducts and can spread to other parts of the breast and nearby structures.

Breast neoplasms are usually detected through screening methods such as mammography, ultrasound, or MRI, or through self-examination or clinical examination. Treatment options for breast neoplasms depend on several factors, including the type and stage of the tumor, the patient's age and overall health, and personal preferences. Treatment may include surgery, radiation therapy, chemotherapy, hormone therapy, or targeted therapy.

DNA repair-deficiency disorders are a group of genetic conditions that result from mutations in genes responsible for the repair and maintenance of DNA. These disorders are characterized by increased sensitivity to environmental factors that can damage DNA, such as ultraviolet (UV) radiation, chemicals, and free radicals. As a result, individuals with these disorders have an increased risk of developing various types of cancer, neurological disorders, premature aging, and other health problems.

Examples of DNA repair-deficiency disorders include xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, and Bloom syndrome. These conditions are typically inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to develop the disorder.

Treatment for DNA repair-deficiency disorders is focused on managing symptoms and preventing complications. This may include avoiding exposure to UV radiation, using sunscreens and protective clothing, and undergoing regular cancer screenings. In some cases, medications or other therapies may be used to treat specific symptoms or complications of the disorder.

An oocyte, also known as an egg cell or female gamete, is a large specialized cell found in the ovary of female organisms. It contains half the number of chromosomes as a normal diploid cell, as it is the product of meiotic division. Oocytes are surrounded by follicle cells and are responsible for the production of female offspring upon fertilization with sperm. The term "oocyte" specifically refers to the immature egg cell before it reaches full maturity and is ready for fertilization, at which point it is referred to as an ovum or egg.

In genetics, sequence alignment is the process of arranging two or more DNA, RNA, or protein sequences to identify regions of similarity or homology between them. This is often done using computational methods to compare the nucleotide or amino acid sequences and identify matching patterns, which can provide insight into evolutionary relationships, functional domains, or potential genetic disorders. The alignment process typically involves adjusting gaps and mismatches in the sequences to maximize the similarity between them, resulting in an aligned sequence that can be visually represented and analyzed.

T-lymphocytes, also known as T-cells, are a type of white blood cell that plays a key role in the adaptive immune system's response to infection. They are produced in the bone marrow and mature in the thymus gland. There are several different types of T-cells, including CD4+ helper T-cells, CD8+ cytotoxic T-cells, and regulatory T-cells (Tregs).

CD4+ helper T-cells assist in activating other immune cells, such as B-lymphocytes and macrophages. They also produce cytokines, which are signaling molecules that help coordinate the immune response. CD8+ cytotoxic T-cells directly kill infected cells by releasing toxic substances. Regulatory T-cells help maintain immune tolerance and prevent autoimmune diseases by suppressing the activity of other immune cells.

T-lymphocytes are important in the immune response to viral infections, cancer, and other diseases. Dysfunction or depletion of T-cells can lead to immunodeficiency and increased susceptibility to infections. On the other hand, an overactive T-cell response can contribute to autoimmune diseases and chronic inflammation.

'Drosophila proteins' refer to the proteins that are expressed in the fruit fly, Drosophila melanogaster. This organism is a widely used model system in genetics, developmental biology, and molecular biology research. The study of Drosophila proteins has contributed significantly to our understanding of various biological processes, including gene regulation, cell signaling, development, and aging.

Some examples of well-studied Drosophila proteins include:

1. HSP70 (Heat Shock Protein 70): A chaperone protein involved in protein folding and protection from stress conditions.
2. TUBULIN: A structural protein that forms microtubules, important for cell division and intracellular transport.
3. ACTIN: A cytoskeletal protein involved in muscle contraction, cell motility, and maintenance of cell shape.
4. BETA-GALACTOSIDASE (LACZ): A reporter protein often used to monitor gene expression patterns in transgenic flies.
5. ENDOGLIN: A protein involved in the development of blood vessels during embryogenesis.
6. P53: A tumor suppressor protein that plays a crucial role in preventing cancer by regulating cell growth and division.
7. JUN-KINASE (JNK): A signaling protein involved in stress response, apoptosis, and developmental processes.
8. DECAPENTAPLEGIC (DPP): A member of the TGF-β (Transforming Growth Factor Beta) superfamily, playing essential roles in embryonic development and tissue homeostasis.

These proteins are often studied using various techniques such as biochemistry, genetics, molecular biology, and structural biology to understand their functions, interactions, and regulation within the cell.

Protein transport, in the context of cellular biology, refers to the process by which proteins are actively moved from one location to another within or between cells. This is a crucial mechanism for maintaining proper cell function and regulation.

Intracellular protein transport involves the movement of proteins within a single cell. Proteins can be transported across membranes (such as the nuclear envelope, endoplasmic reticulum, Golgi apparatus, or plasma membrane) via specialized transport systems like vesicles and transport channels.

Intercellular protein transport refers to the movement of proteins from one cell to another, often facilitated by exocytosis (release of proteins in vesicles) and endocytosis (uptake of extracellular substances via membrane-bound vesicles). This is essential for communication between cells, immune response, and other physiological processes.

It's important to note that any disruption in protein transport can lead to various diseases, including neurological disorders, cancer, and metabolic conditions.

Site-directed mutagenesis is a molecular biology technique used to introduce specific and targeted changes to a specific DNA sequence. This process involves creating a new variant of a gene or a specific region of interest within a DNA molecule by introducing a planned, deliberate change, or mutation, at a predetermined site within the DNA sequence.

The methodology typically involves the use of molecular tools such as PCR (polymerase chain reaction), restriction enzymes, and/or ligases to introduce the desired mutation(s) into a plasmid or other vector containing the target DNA sequence. The resulting modified DNA molecule can then be used to transform host cells, allowing for the production of large quantities of the mutated gene or protein for further study.

Site-directed mutagenesis is a valuable tool in basic research, drug discovery, and biotechnology applications where specific changes to a DNA sequence are required to understand gene function, investigate protein structure/function relationships, or engineer novel biological properties into existing genes or proteins.

Scleral buckling is a surgical procedure used to treat retinal detachment, a serious eye condition that can cause vision loss. In this procedure, the sclera (the white outer coat of the eye) is "buckled" or indented with a piece of silicone rubber or sponge material. This brings the detached retina into contact with the wall of the eye, allowing the retina to reattach and heal. The buckle is usually left in place permanently. Scleral buckling has been a standard treatment for retinal detachment for many years and is often combined with vitrectomy or cryotherapy to improve outcomes.

Chromates are the salts or esters of chromic acid (H2CrO4) that contain the chromate ion (CrO4 2-). They are characterized by their yellow or orange color. Chromates are widely used in industry, for example as corrosion inhibitors, pigments, and wood preservatives. However, they are also toxic and carcinogenic, and exposure to chromates can cause a range of health problems, including respiratory issues, skin irritation, and damage to the eyes and mucous membranes. Therefore, their use is regulated in many countries, and appropriate safety measures must be taken when handling them.

Recombinant fusion proteins are artificially created biomolecules that combine the functional domains or properties of two or more different proteins into a single protein entity. They are generated through recombinant DNA technology, where the genes encoding the desired protein domains are linked together and expressed as a single, chimeric gene in a host organism, such as bacteria, yeast, or mammalian cells.

The resulting fusion protein retains the functional properties of its individual constituent proteins, allowing for novel applications in research, diagnostics, and therapeutics. For instance, recombinant fusion proteins can be designed to enhance protein stability, solubility, or immunogenicity, making them valuable tools for studying protein-protein interactions, developing targeted therapies, or generating vaccines against infectious diseases or cancer.

Examples of recombinant fusion proteins include:

1. Etaglunatide (ABT-523): A soluble Fc fusion protein that combines the heavy chain fragment crystallizable region (Fc) of an immunoglobulin with the extracellular domain of the human interleukin-6 receptor (IL-6R). This fusion protein functions as a decoy receptor, neutralizing IL-6 and its downstream signaling pathways in rheumatoid arthritis.
2. Etanercept (Enbrel): A soluble TNF receptor p75 Fc fusion protein that binds to tumor necrosis factor-alpha (TNF-α) and inhibits its proinflammatory activity, making it a valuable therapeutic option for treating autoimmune diseases like rheumatoid arthritis, ankylosing spondylitis, and psoriasis.
3. Abatacept (Orencia): A fusion protein consisting of the extracellular domain of cytotoxic T-lymphocyte antigen 4 (CTLA-4) linked to the Fc region of an immunoglobulin, which downregulates T-cell activation and proliferation in autoimmune diseases like rheumatoid arthritis.
4. Belimumab (Benlysta): A monoclonal antibody that targets B-lymphocyte stimulator (BLyS) protein, preventing its interaction with the B-cell surface receptor and inhibiting B-cell activation in systemic lupus erythematosus (SLE).
5. Romiplostim (Nplate): A fusion protein consisting of a thrombopoietin receptor agonist peptide linked to an immunoglobulin Fc region, which stimulates platelet production in patients with chronic immune thrombocytopenia (ITP).
6. Darbepoetin alfa (Aranesp): A hyperglycosylated erythropoiesis-stimulating protein that functions as a longer-acting form of recombinant human erythropoietin, used to treat anemia in patients with chronic kidney disease or cancer.
7. Palivizumab (Synagis): A monoclonal antibody directed against the F protein of respiratory syncytial virus (RSV), which prevents RSV infection and is administered prophylactically to high-risk infants during the RSV season.
8. Ranibizumab (Lucentis): A recombinant humanized monoclonal antibody fragment that binds and inhibits vascular endothelial growth factor A (VEGF-A), used in the treatment of age-related macular degeneration, diabetic retinopathy, and other ocular disorders.
9. Cetuximab (Erbitux): A chimeric monoclonal antibody that binds to epidermal growth factor receptor (EGFR), used in the treatment of colorectal cancer and head and neck squamous cell carcinoma.
10. Adalimumab (Humira): A fully humanized monoclonal antibody that targets tumor necrosis factor-alpha (TNF-α), used in the treatment of various inflammatory diseases, including rheumatoid arthritis, psoriasis, and Crohn's disease.
11. Bevacizumab (Avastin): A recombinant humanized monoclonal antibody that binds to VEGF-A, used in the treatment of various cancers, including colorectal, lung, breast, and kidney cancer.
12. Trastuzumab (Herceptin): A humanized monoclonal antibody that targets HER2/neu receptor, used in the treatment of breast cancer.
13. Rituximab (Rituxan): A chimeric monoclonal antibody that binds to CD20 antigen on B cells, used in the treatment of non-Hodgkin's lymphoma and rheumatoid arthritis.
14. Palivizumab (Synagis): A humanized monoclonal antibody that binds to the F protein of respiratory syncytial virus, used in the prevention of respiratory syncytial virus infection in high-risk infants.
15. Infliximab (Remicade): A chimeric monoclonal antibody that targets TNF-α, used in the treatment of various inflammatory diseases, including Crohn's disease, ulcerative colitis, rheumatoid arthritis, and ankylosing spondylitis.
16. Natalizumab (Tysabri): A humanized monoclonal antibody that binds to α4β1 integrin, used in the treatment of multiple sclerosis and Crohn's disease.
17. Adalimumab (Humira): A fully human monoclonal antibody that targets TNF-α, used in the treatment of various inflammatory diseases, including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn's disease, and ulcerative colitis.
18. Golimumab (Simponi): A fully human monoclonal antibody that targets TNF-α, used in the treatment of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and ulcerative colitis.
19. Certolizumab pegol (Cimzia): A PEGylated Fab' fragment of a humanized monoclonal antibody that targets TNF-α, used in the treatment of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and Crohn's disease.
20. Ustekinumab (Stelara): A fully human monoclonal antibody that targets IL-12 and IL-23, used in the treatment of psoriasis, psoriatic arthritis, and Crohn's disease.
21. Secukinumab (Cosentyx): A fully human monoclonal antibody that targets IL-17A, used in the treatment of psoriasis, psoriatic arthritis, and ankylosing spondylitis.
22. Ixekizumab (Taltz): A fully human monoclonal antibody that targets IL-17A, used in the treatment of psoriasis and psoriatic arthritis.
23. Brodalumab (Siliq): A fully human monoclonal antibody that targets IL-17 receptor A, used in the treatment of psoriasis.
24. Sarilumab (Kevzara): A fully human monoclonal antibody that targets the IL-6 receptor, used in the treatment of rheumatoid arthritis.
25. Tocilizumab (Actemra): A humanized monoclonal antibody that targets the IL-6 receptor, used in the treatment of rheumatoid arthritis, systemic juvenile idiopathic arthritis, polyarticular juvenile idiopathic arthritis, giant cell arteritis, and chimeric antigen receptor T-cell-induced cytokine release syndrome.
26. Siltuximab (Sylvant): A chimeric monoclonal antibody that targets IL-6, used in the treatment of multicentric Castleman disease.
27. Satralizumab (Enspryng): A humanized monoclonal antibody that targets IL-6 receptor alpha, used in the treatment of neuromyelitis optica spectrum disorder.
28. Sirukumab (Plivensia): A human monoclonal antibody that targets IL-6, used in the treatment

Molecular cloning is a laboratory technique used to create multiple copies of a specific DNA sequence. This process involves several steps:

1. Isolation: The first step in molecular cloning is to isolate the DNA sequence of interest from the rest of the genomic DNA. This can be done using various methods such as PCR (polymerase chain reaction), restriction enzymes, or hybridization.
2. Vector construction: Once the DNA sequence of interest has been isolated, it must be inserted into a vector, which is a small circular DNA molecule that can replicate independently in a host cell. Common vectors used in molecular cloning include plasmids and phages.
3. Transformation: The constructed vector is then introduced into a host cell, usually a bacterial or yeast cell, through a process called transformation. This can be done using various methods such as electroporation or chemical transformation.
4. Selection: After transformation, the host cells are grown in selective media that allow only those cells containing the vector to grow. This ensures that the DNA sequence of interest has been successfully cloned into the vector.
5. Amplification: Once the host cells have been selected, they can be grown in large quantities to amplify the number of copies of the cloned DNA sequence.

Molecular cloning is a powerful tool in molecular biology and has numerous applications, including the production of recombinant proteins, gene therapy, functional analysis of genes, and genetic engineering.

Proto-oncogene proteins, such as c-Myc, are crucial regulators of normal cell growth, differentiation, and apoptosis (programmed cell death). When proto-oncogenes undergo mutations or alterations in their regulation, they can become overactive or overexpressed, leading to the formation of oncogenes. Oncogenic forms of c-Myc contribute to uncontrolled cell growth and division, which can ultimately result in cancer development.

The c-Myc protein is a transcription factor that binds to specific DNA sequences, influencing the expression of target genes involved in various cellular processes, such as:

1. Cell cycle progression: c-Myc promotes the expression of genes required for the G1 to S phase transition, driving cells into the DNA synthesis and division phase.
2. Metabolism: c-Myc regulates genes associated with glucose metabolism, glycolysis, and mitochondrial function, enhancing energy production in rapidly dividing cells.
3. Apoptosis: c-Myc can either promote or inhibit apoptosis, depending on the cellular context and the presence of other regulatory factors.
4. Differentiation: c-Myc generally inhibits differentiation by repressing genes that are necessary for specialized cell functions.
5. Angiogenesis: c-Myc can induce the expression of pro-angiogenic factors, promoting the formation of new blood vessels to support tumor growth.

Dysregulation of c-Myc is frequently observed in various types of cancer, making it an important therapeutic target for cancer treatment.

Drug resistance in neoplasms (also known as cancer drug resistance) refers to the ability of cancer cells to withstand the effects of chemotherapeutic agents or medications designed to kill or inhibit the growth of cancer cells. This can occur due to various mechanisms, including changes in the cancer cell's genetic makeup, alterations in drug targets, increased activity of drug efflux pumps, and activation of survival pathways.

Drug resistance can be intrinsic (present at the beginning of treatment) or acquired (developed during the course of treatment). It is a significant challenge in cancer therapy as it often leads to reduced treatment effectiveness, disease progression, and poor patient outcomes. Strategies to overcome drug resistance include the use of combination therapies, development of new drugs that target different mechanisms, and personalized medicine approaches that consider individual patient and tumor characteristics.

DNA cleavage is the breaking of the phosphodiester bonds in the DNA molecule, resulting in the separation of the two strands of the double helix. This process can occur through chemical or enzymatic reactions and can result in various types of damage to the DNA molecule, including single-strand breaks, double-strand breaks, and base modifications.

Enzymatic DNA cleavage is typically carried out by endonucleases, which are enzymes that cut DNA molecules at specific sequences or structures. There are two main types of endonucleases: restriction endonucleases and repair endonucleases. Restriction endonucleases recognize and cleave specific DNA sequences, often used in molecular biology techniques such as genetic engineering and cloning. Repair endonucleases, on the other hand, are involved in DNA repair processes and recognize and cleave damaged or abnormal DNA structures.

Chemical DNA cleavage can occur through various mechanisms, including oxidation, alkylation, or hydrolysis of the phosphodiester bonds. Chemical agents such as hydrogen peroxide, formaldehyde, or hydrazine can induce chemical DNA cleavage and are often used in laboratory settings for various purposes, such as DNA fragmentation or labeling.

Overall, DNA cleavage is an essential process in many biological functions, including DNA replication, repair, and recombination. However, excessive or improper DNA cleavage can lead to genomic instability, mutations, and cell death.

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which remains unchanged at the end of the reaction. A catalyst lowers the activation energy required for the reaction to occur, thereby allowing the reaction to proceed more quickly and efficiently. This can be particularly important in biological systems, where enzymes act as catalysts to speed up metabolic reactions that are essential for life.

A neoplasm is a tumor or growth that is formed by an abnormal and excessive proliferation of cells, which can be benign or malignant. Neoplasm proteins are therefore any proteins that are expressed or produced in these neoplastic cells. These proteins can play various roles in the development, progression, and maintenance of neoplasms.

Some neoplasm proteins may contribute to the uncontrolled cell growth and division seen in cancer, such as oncogenic proteins that promote cell cycle progression or inhibit apoptosis (programmed cell death). Others may help the neoplastic cells evade the immune system, allowing them to proliferate undetected. Still others may be involved in angiogenesis, the formation of new blood vessels that supply the tumor with nutrients and oxygen.

Neoplasm proteins can also serve as biomarkers for cancer diagnosis, prognosis, or treatment response. For example, the presence or level of certain neoplasm proteins in biological samples such as blood or tissue may indicate the presence of a specific type of cancer, help predict the likelihood of cancer recurrence, or suggest whether a particular therapy will be effective.

Overall, understanding the roles and behaviors of neoplasm proteins can provide valuable insights into the biology of cancer and inform the development of new diagnostic and therapeutic strategies.

Cell extracts refer to the mixture of cellular components that result from disrupting or breaking open cells. The process of obtaining cell extracts is called cell lysis. Cell extracts can contain various types of molecules, such as proteins, nucleic acids (DNA and RNA), carbohydrates, lipids, and metabolites, depending on the methods used for cell disruption and extraction.

Cell extracts are widely used in biochemical and molecular biology research to study various cellular processes and pathways. For example, cell extracts can be used to measure enzyme activities, analyze protein-protein interactions, characterize gene expression patterns, and investigate metabolic pathways. In some cases, specific cellular components can be purified from the cell extracts for further analysis or application, such as isolating pure proteins or nucleic acids.

It is important to note that the composition of cell extracts may vary depending on the type of cells, the growth conditions, and the methods used for cell disruption and extraction. Therefore, it is essential to optimize the experimental conditions to obtain representative and meaningful results from cell extract studies.

Genotype, in genetics, refers to the complete heritable genetic makeup of an individual organism, including all of its genes. It is the set of instructions contained in an organism's DNA for the development and function of that organism. The genotype is the basis for an individual's inherited traits, and it can be contrasted with an individual's phenotype, which refers to the observable physical or biochemical characteristics of an organism that result from the expression of its genes in combination with environmental influences.

It is important to note that an individual's genotype is not necessarily identical to their genetic sequence. Some genes have multiple forms called alleles, and an individual may inherit different alleles for a given gene from each parent. The combination of alleles that an individual inherits for a particular gene is known as their genotype for that gene.

Understanding an individual's genotype can provide important information about their susceptibility to certain diseases, their response to drugs and other treatments, and their risk of passing on inherited genetic disorders to their offspring.

A point mutation is a type of genetic mutation where a single nucleotide base (A, T, C, or G) in DNA is altered, deleted, or substituted with another nucleotide. Point mutations can have various effects on the organism, depending on the location of the mutation and whether it affects the function of any genes. Some point mutations may not have any noticeable effect, while others might lead to changes in the amino acids that make up proteins, potentially causing diseases or altering traits. Point mutations can occur spontaneously due to errors during DNA replication or be inherited from parents.

Linear Energy Transfer (LET) is a concept in radiation physics that describes the amount of energy that is transferred from an ionizing particle to a medium per unit length along its path. It is usually expressed in units of keV/μm (kiloelectron volts per micrometer). High-LET radiations, such as alpha particles and heavy ions, transfer more energy to the medium per unit length than low-LET radiations, such as X-rays and gamma rays. This results in a higher probability of producing dense ionizations and causing biological damage along the particle's path. Therefore, LET is an important factor in determining the relative biological effectiveness (RBE) of different types of radiation.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

In the context of medicine, particularly in psychiatry and psychology, "Narcissus" or "Narcissistic" is not typically used as a standalone medical definition. However, it is associated with Narcissism and Narcissistic Personality Disorder (NPD).

Narcissism is a personality trait characterized by a grandiose sense of self-importance, a lack of empathy for others, a need for excessive admiration, and feelings of entitlement. It's named after the Greek mythological figure Narcissus, who fell in love with his own reflection.

Narcissistic Personality Disorder (NPD) is a mental disorder characterized by these narcissistic traits, but to such an extent that they cause significant impairment in personal relationships and professional life.

Please note that only a qualified healthcare professional can diagnose such conditions.

Chromosomes are thread-like structures that contain genetic material, i.e., DNA and proteins, present in the nucleus of human cells. In humans, there are 23 pairs of chromosomes, for a total of 46 chromosomes, in each diploid cell. Twenty-two of these pairs are called autosomal chromosomes, which come in identical pairs and contain genes that determine various traits unrelated to sex.

The last pair is referred to as the sex chromosomes (X and Y), which determines a person's biological sex. Females have two X chromosomes (46, XX), while males possess one X and one Y chromosome (46, XY). Chromosomes vary in size, with the largest being chromosome 1 and the smallest being the Y chromosome.

Human chromosomes are typically visualized during mitosis or meiosis using staining techniques that highlight their banding patterns, allowing for identification of specific regions and genes. Chromosomal abnormalities can lead to various genetic disorders, including Down syndrome (trisomy 21), Turner syndrome (monosomy X), and Klinefelter syndrome (XXY).

Radiation-sensitizing agents are drugs that make cancer cells more sensitive to radiation therapy. These agents work by increasing the ability of radiation to damage the DNA of cancer cells, which can lead to more effective tumor cell death. This means that lower doses of radiation may be required to achieve the same therapeutic effect, reducing the potential for damage to normal tissues surrounding the tumor.

Radiation-sensitizing agents are often used in conjunction with radiation therapy to improve treatment outcomes for patients with various types of cancer. They can be given either systemically (through the bloodstream) or locally (directly to the tumor site). The choice of agent and the timing of administration depend on several factors, including the type and stage of cancer, the patient's overall health, and the specific radiation therapy protocol being used.

It is important to note that while radiation-sensitizing agents can enhance the effectiveness of radiation therapy, they may also increase the risk of side effects. Therefore, careful monitoring and management of potential toxicities are essential during treatment.

VDJ exons refer to specific regions within the genes that encode the variable region of immunoglobulins, also known as antibodies, in the human immune system. The term "VDJ" stands for the three types of gene segments that are involved in the generation of a diverse repertoire of antibodies: Variable (V), Diversity (D), and Joining (J) segments.

Exons are regions of DNA that code for protein sequences and are spliced together during the process of gene transcription to form mature mRNA molecules. In the case of VDJ exons, these regions correspond to the V, D, and J gene segments that undergo a process called somatic recombination during the development of B lymphocytes in the bone marrow.

Through this process, one V segment, one D segment (in heavy chain genes only), one J segment, and a short leader sequence are randomly selected and joined together to form a single exon that encodes the variable region of an antibody molecule. This allows for the generation of a vast array of different antibodies with unique specificities, enabling the immune system to recognize and respond to a wide variety of pathogens.

Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) is a laboratory technique used in molecular biology to amplify and detect specific DNA sequences. This technique is particularly useful for the detection and quantification of RNA viruses, as well as for the analysis of gene expression.

The process involves two main steps: reverse transcription and polymerase chain reaction (PCR). In the first step, reverse transcriptase enzyme is used to convert RNA into complementary DNA (cDNA) by reading the template provided by the RNA molecule. This cDNA then serves as a template for the PCR amplification step.

In the second step, the PCR reaction uses two primers that flank the target DNA sequence and a thermostable polymerase enzyme to repeatedly copy the targeted cDNA sequence. The reaction mixture is heated and cooled in cycles, allowing the primers to anneal to the template, and the polymerase to extend the new strand. This results in exponential amplification of the target DNA sequence, making it possible to detect even small amounts of RNA or cDNA.

RT-PCR is a sensitive and specific technique that has many applications in medical research and diagnostics, including the detection of viruses such as HIV, hepatitis C virus, and SARS-CoV-2 (the virus that causes COVID-19). It can also be used to study gene expression, identify genetic mutations, and diagnose genetic disorders.

A nucleic acid heteroduplex is a double-stranded structure formed by the pairing of two complementary single strands of nucleic acids (DNA or RNA) that are derived from different sources. The term "hetero" refers to the fact that the two strands are not identical and come from different parents, genes, or organisms.

Heteroduplexes can form spontaneously during processes like genetic recombination, where DNA repair mechanisms may mistakenly pair complementary regions between two different double-stranded DNA molecules. They can also be generated intentionally in laboratory settings for various purposes, such as analyzing the similarity of DNA sequences or detecting mutations.

Heteroduplexes are often used in molecular biology techniques like polymerase chain reaction (PCR) and DNA sequencing, where they can help identify mismatches, insertions, deletions, or other sequence variations between the two parental strands. These variations can provide valuable information about genetic diversity, evolutionary relationships, and disease-causing mutations.

Esterases are a group of enzymes that catalyze the hydrolysis of ester bonds in esters, producing alcohols and carboxylic acids. They are widely distributed in plants, animals, and microorganisms and play important roles in various biological processes, such as metabolism, digestion, and detoxification.

Esterases can be classified into several types based on their substrate specificity, including carboxylesterases, cholinesterases, lipases, and phosphatases. These enzymes have different structures and mechanisms of action but all share the ability to hydrolyze esters.

Carboxylesterases are the most abundant and diverse group of esterases, with a wide range of substrate specificity. They play important roles in the metabolism of drugs, xenobiotics, and lipids. Cholinesterases, on the other hand, specifically hydrolyze choline esters, such as acetylcholine, which is an important neurotransmitter in the nervous system. Lipases are a type of esterase that preferentially hydrolyzes triglycerides and plays a crucial role in fat digestion and metabolism. Phosphatases are enzymes that remove phosphate groups from various molecules, including esters, and have important functions in signal transduction and other cellular processes.

Esterases can also be used in industrial applications, such as in the production of biodiesel, detergents, and food additives. They are often produced by microbial fermentation or extracted from plants and animals. The use of esterases in biotechnology is an active area of research, with potential applications in biofuel production, bioremediation, and medical diagnostics.

Mutagenicity tests are a type of laboratory assays used to identify agents that can cause genetic mutations. These tests detect changes in the DNA of organisms, such as bacteria, yeast, or mammalian cells, after exposure to potential mutagens. The most commonly used mutagenicity test is the Ames test, which uses a strain of Salmonella bacteria that is sensitive to mutagens. If a chemical causes an increase in the number of revertants (reversion to the wild type) in the bacterial population, it is considered to be a mutagen. Other tests include the mouse lymphoma assay and the chromosomal aberration test. These tests are used to evaluate the potential genotoxicity of chemicals and are an important part of the safety evaluation process for new drugs, chemicals, and other substances.

"Review: 'Breaking News' (Kannada)". DNA. 19 May 2012. "Breaking News: Broken views". Bangalore Mirror. 19 May 2012. Breaking ... Breaking News is a light-hearted movie with bad production values". Shruti I. L from DNA wrote "Ramakrishna, Sangeetha and ... Breaking News is a 2012 Kannada satirical film directed, written and produced by Nagathihalli Chandrashekar. It stars Ajay Rao ... ". "BREAKING NEWS MOVIE REVIEW". The Times of India. 16 May 2016. "Review: Breaking News has no soul". Rediff.com. 21 May 2012 ...
Break Point' trailer out: A tale of Mahesh Bhupati-Leander Paes' journey from bromance to break-up". DNA India. 17 September ... "Watch Break Point Web Series, Show Online in HD on ZEE5". Shekhar, Mimansa (1 October 2021). "Break Point: Leander Paes, Mahesh ... Break Point on ZEE5 Break Point at IMDb (CS1 errors: generic name, Articles with short description, Short description matches ... "Break Point: Mahesh Bhupati-Leander Paes series tells their story 'from bromance to break-up'". The Indian Express. 15 ...
"DNA: Munawwar Rana's words on Taliban more 'dangerous' than bullets?". DNA India. Retrieved 12 January 2022. Now ,, Times. " ... France आतंकी हमले को लेकर शायर Munawwar Rana ने फिर दिया बड़ा बयान , Breaking News , Latest Update, retrieved 29 January 2022 " ... "Munawwar Rana stands in support of France attacker, says caricatures made to defame Hussain Bohra Islam". DNA India. 31 October ...
Gorczyca W, Traganos F, Jesionowska H, Darzynkiewicz Z (1993). "Presence of DNA strand breaks and increased sensitivity of DNA ... hydroxyl termini of DNA double strand breaks. It may also label cells having DNA damage by other means than in the course of ... hydroxyl termini in the double-strand DNA breaks generated during apoptosis. TUNEL is a method for detecting apoptotic DNA ... The fluorochrome-based TUNEL assay applicable for flow cytometry, combining the detection of DNA strand breaks with respect to ...
The Sri Lankan Civil War broke out with the Liberation Tigers of Tamil Eelam (LTTE), which was demanding an independent Tamil ... "My sins washed away, says Nalini Sriharan". dna. 16 April 2008. "Nalini meets hubby on death row". The Times of India. 11 ... "Rajiv Gandhi's killer Nalini breaks down". NDTV.com. 7 September 2011. Retrieved 27 February 2013. "Nalini Sriharan back in ... Vellore - India - DNA". Dnaindia.com. 7 September 2011. Retrieved 27 February 2013. "Nalini shifted from Vellore jail to Puzhal ...
In a report published on 30 October 2012 in DNA, K. Ragothaman, former chief investigator of the CBI, talks about his new book ... In fact, the then governor of Tamil Nadu Bhishma Narain Singh, broke official protocol and twice warned Gandhi about the threat ... "My sins washed away, says Nalini Sriharan". DNA India. IANS. 16 April 2008. Archived from the original on 4 April 2010. ... "Nalini Sriharan back in Vellore". DNA India. 7 September 2011. Retrieved 30 August 2013. "Nalini shifted from Vellore jail to ...
"Alzheimer's insight from DNA study". BBC. 28 October 2013. Retrieved 28 October 2013. "Vicarious AI breaks CAPTCHA 'Turing test ... The DNA is from a 400,000-year-old hominin femur bone fossil uncovered in Spain and matches the DNA of extinct human Denisovans ... on a single strand of synthetic DNA. DNA has immense potential as a storage medium, and may become commercially available for ... After DNA testing, scientists confirm that a medieval skeleton unearthed in Leicester is that of the defeated Plantagenet king ...
... is ambitious and exciting." Sarita Tanwar of DNA gave it 3.5 stars and wrote, "Krrish 3 is fast-paced and the VFX ... "Roshans break records! - Entertainment". Daily News and Analysis. 18 August 2013. Retrieved 25 October 2013. "Krrish 3 ... DNA Web Team. Retrieved 11 November 2013. "iTunes Music - Krrish 3 (Original Motion Picture Soundtrack) by Rajesh Roshan". ... "Film review: Krrish 3 is an entertaining mix of spectacle and human-scale drama - Entertainment - DNA". Daily News and Analysis ...
Sharma, Yukti (10 January 2019). "I'm still an outsider, says Sumedha Karmahe". DNA India. Retrieved 22 July 2021. "Sumedha ... Odisha Breaking News , Latest Odisha News. Retrieved 22 July 2021. ...
DNA polymerase and other accessory factors follows by replacing the missing DNA via DNA synthesis. Ligase then attaches the DNA ... April 2007). "Autophosphorylation of DNA-PKCS regulates its dynamics at DNA double-strand breaks". The Journal of Cell Biology ... Thirdly, the cleavage of different DNA structures such as reversed or blocked DNA replication forks, R-loops and DNA ... "Interaction of the Ku heterodimer with the DNA ligase IV/Xrcc4 complex and its regulation by DNA-PK". DNA Repair. 6 (6): 712- ...
It was discovered by DNA tests and named recently. "Talamancan Palm-Pitviper: Cryptic New Species of Venomous Snake Identified ... in Costa Rica , Biology , Sci-News.com". Breaking Science News , Sci-News.com. Retrieved 2017-02-17. "New Speckled Venomous ...
The song was released on May 17, 2018 as the lead single to their ninth studio album DNA (their eighth in the US). The single ... "Don't Go Breaking My Heart" debuted on May 17, 2018, and in its first week ranked 22nd in digital sales. The song was deemed by ... "Don't Go Breaking My Heart - Single by Backstreet Boys". iTunes Store (Apple Inc.). 18 May 2018. "Backstreet Boys - Don't Go ... "Don't Go Breaking My Heart" is a song by American vocal group Backstreet Boys. ...
Through his discovery that the DNA-dependent protein kinase (DNA-PK) enzyme is activated by DNA double-strand breaks (DSBs), ... Polo SE, Jackson SP (2011). "Dynamics of DNA damage response proteins at DNA breaks: a focus on protein modifications". Genes ... Blackford AN, Jackson SP (2017). "ATM, ATR, and DNA-PK: The Trinity at the Heart of the DNA Damage Response". Molecular Cell. ... Gottlieb TM, Jackson SP (1993). "The DNA-dependent protein kinase: requirement for DNA ends and association with Ku antigen". ...
Michael Balter (2008). "DNA from Fossil Feces breaks Clovis Barrier". Science. 320 (5872): 37. doi:10.1126/science.320.5872.37 ... But in 2014, the autosomal DNA of a 12,500+-year-old infant from Montana was sequenced. The DNA was taken from a skeleton ... analysis of published DNA sequences for 19 Siberian populations does not favor the latter scenario. Spearheads and DNA found at ... Analysis of DNA recovered from the remains indicates that Anzick-1 is more closely related to all of the indigenous peoples of ...
Forejt J (February 2016). "Genetics: Asymmetric breaks in DNA cause sterility". Nature. 530 (7589): 167-8. Bibcode:2016Natur. ... Upon binding to DNA, PRDM9 catalyzes trimethylation of Histone 3 at lysine 4 and lysine 36. As a result, local nucleosomes are ... Hotspots are regions of DNA about 1-2kb in length. There are approximately 30,000 to 50,000 hotspots within the human genome ... PRDM9 is responsible for positioning recombination hotspots during meiosis by binding a DNA sequence motif encoded in its zinc ...
"Do DNA Double-Strand Breaks Drive Aging?". Molecular Cell. 63 (5): 729-738. doi:10.1016/j.molcel.2016.08.004. ISSN 1097-2765. ... DNA replication checkpoints are located at the G1, S and G2 phase to check if DNA is normal, and withdraws the cell from the ... appearing in their DNA. Therefore, the wearing off of DNA would not occur, and the genetic information would remain the same, ... The DNA structure in these organisms are in the form of circular chromosomes, meaning there would be no "ends" ...
18 January - A stampede broke out in Mumbai in which 18 died. The stampede broke out at the residence of the religious leader ... "Kerala to close down 700 bars, Sundays to be dry". DNA India. 21 August 2014. Retrieved 28 November 2014. "Coal block ... "Intelligence meet breaks India-US diplomatic ice". The Hindu. 14 January 2014. Retrieved 2 October 2014. "US returns three ' ... "Jammu and Kashmir: 11 security men, 6 militants killed in attack on Uri Army camp; fresh encounter breaks out in Soura area of ...
... and later breaking the record for the having the highest chart entry for a debut album by British girl group, breaking a record ... music.apple.com/gb/album/dna-the-deluxe-edition/636703835 "DNA (Deluxe)". Spotify. "DNA - Little Mix , Credits , AllMusic". ... The DNA Tour was the first tour by British girl group Little Mix, in support of their first studio album DNA (2012). The tour ... DNA has peaked in the top 10 of eight countries worldwide, including the UK, Australia and Italy. In the US, DNA entered the ...
"Massive fire breaks out in Kolkata's New Market area". No. DNA. 18 May 2015. Archived from the original on 6 February 2023. ... "Massive fire breaks out in New Market". The Hindu. 19 May 2015. Archived from the original on 1 January 2017. Retrieved 12 June ...
... removal of DNA-protein crosslinks; and (5) removal of double-strand breaks. Such repair pathways can function to protect ... May 2015). "DNA repair. Proteomics reveals dynamic assembly of repair complexes during bypass of DNA cross-links". Science. 348 ... In addition to the repair of DNA interstrand crosslinks, indicated above, multiple DNA repair processes operating in ... DNA replication stress refers to the state of a cell whose genome is exposed to various stresses. The events that contribute to ...
"India's twins pose DNA puzzle". 2004-02-23. Retrieved 2018-01-08. "قرية "أبو عطوة" المصرية.. مدمنة توائم,". archive.aawsat.com ... Lubin, Rhian (2016-01-27). "This village breaks records for 'multiple' reasons..." mirror. Retrieved 2018-01-08. "The Land Of ... Category:Populated places with highest incidence of multiple birth "Babies come in twos in this Kerala village". DNA. Retrieved ...
Young men and boys form teams, make a human pyramid, and attempt to reach or break the pot. As they do so, people surround them ... Ashutosh Shukla; Geeta Desai (27 August 2013). "Dahi handi stakes grow bigger". DNA. Retrieved 23 July 2014. Ambarish Mishra; ... Breaking the pot usually ends up with the contents spilling over the participants. Traditionally, spectators threw water on the ... These groups are called mandals and they go around the local areas, attempting to break as many pots as possible during the ...
"Sachin breaks Shaun Marsh's IPL record for Most Runs scored in a single season and he also Received the Best Batsman and Best ... "Sachin Tendulkar and Sunil Gavaskar: Two masters and the amazing chemistry between the two". DNA India. Archived from the ... During the innings break, he batted an over against Ellyse Perry and Annabel Sutherland at Perry's request. Tendulkar was made ... "IPL: Virat Kohli breaks Sachin Tendulkar's record". The Times of India. 7 May 2016. Archived from the original on 8 May 2016. " ...
Team, DNA Web (1 May 2019). "Details about Mahesh Babu's massive pre-release event of 'Maharshi' for his fans REVEALED!". DNA ... When Ravi tried to apprehend Rishi to not break up with pooja but it led to a fallout between them. As the last semester ... The team then took brief break, with Mahesh Babu and his family going to Dubai for a short holiday. Filming was resumed in the ... Pooja too suspects Rishi's intentions and blames him for Ravi's situation and told he has not change a bit which broke his ...
The possibility that BrdU being substituted for thymine in the genomic DNA could induce double stranded chromosomal breaks and ... The following methods concentrate on the DNA sequencing of a single daughter cell's DNA. At this point the chromosomes are ... a typical DNA library will always contain DNA from both strands. The authors were specifically interested in showing the ... Next, the DNA is incubated with a special dye such that when the BrdU-dye complex is excited by UV light, nascent strands are ...
A new beginning': Lalit Modi announces he is dating Sushmita Sen, calls her 'my better half'; photos break the internet". ... "After split with Rohman Shawl, Sushmita Sen hints at what went wrong in relationship". DNA India. Retrieved 10 January 2022. "' ... Uddin, Zakia (18 January 2013). "Randeep Hooda: 'Break-up with Sushmita Sen changed my life'". Mid-Day. Archived from the ...
"Breaking Free wins big". MidDay. 20 July 2016. Retrieved 20 July 2016. Saagar Gupta at IMDb (Articles with short description, ... "With 31 in tow, India leads list of films to be screened at KASHISH 2019". DNA. 27 May 2019. Retrieved 27 May 2019. "Lesbian, ... They are as follows: Barbara Gittings Human Rights Award at qFLIX Philadelphia 2016, USA (for film 'Breaking Free') Jury Award ... Breaking Free, Evening Shadows. He is the founder team member of Kashish Mumbai Queer Film Festival and has been the Director ...
The record was then broken by Corey Anderson of New Zealand (36 balls), which is currently held by AB de Villiers of South ... "When former Sri Lankan opener Sanath Jayasuriya allegedly leaked his ex-girlfriend's sex tape". DNA India. 8 June 2021. ... "Sri Lanka break one-day record". Cricinfo. Retrieved 5 December 2009. "One Day Internationals: Batting Records - Oldest player ... He was named the Most Valuable Player of 1996 Cricket World Cup and Wisden Cricketers' Almanack broke an age-old tradition by ...
"Congress announces candidates for Gujarat assembly bypolls". DNA India. 29 September 2019. Retrieved 31 May 2021. Desk, India ... Breaking News , India.com. Retrieved 31 May 2021. "Voting begins for bypolls to six Assembly seats in Gujarat". Business ...
Tahseen, Ismat (3 December 2010). "I hope to change the way people listen to 'bhajans': Shivali Bhammer". DNA India. Retrieved ... Shah, Jinal (16 May 2015). "Bhajan Singer Shivali Bhammer on Expanding the Devotional Music Scene". India News, Breaking News ... Breaking News , India.com. Retrieved 3 February 2021. Ryan, Jed; writer, ContributorJed Ryan is a New York City-based freelance ...
Desk, India com Business (27 December 2020). "10 Most Successful Tech CEOs of The Decade". India News, Breaking News , India. ... "Zee Digital continues its growth streak, crosses 150 million users in March 2020: ComScore India". DNA India. 20 May 2020. ... Zee Media and DNA). He was the co-founder of online food ordering platform Foodpanda. He is also the founder of omni-channel ... Breaking News , India.com. Retrieved 11 January 2021. {{cite web}}: ,first= has generic name (help) Bureau, BW Online. "Leading ...
During meiosis, Mer2 and the Rec114-Mei4 complex form condensates that facilitate the formation of double-strand DNA breaks by ... is critical for genome stability across sexual cycles-relies on homologous recombination initiated by DNA double-strand breaks ... Mutations that weaken protein-DNA interactions strongly disrupt both condensate formation and DSBs in vivo, and thus these ... but the protein assemblies that execute and control DNA breakage are poorly understood. Here we address this through the ...
The importance of DNA damage as a possible driver of the aging process went from being widely recognized to then forgotten, and ... Are DNA damage and mutations possible causes or consequences of aging? This question has been hotly debated by ... DNA double strand break repair, aging and the chromatin connection Mutat Res. 2016 Jun:788:2-6. doi: 10.1016/j.mrfmmm.2016.02. ... DNA double strand breaks (DSBs) are particularly relevant to aging because of their toxicity, increased frequency with age and ...
You have to enable JavaScript in your browsers settings in order to use the eReader.. Or try downloading the content offline. DOWNLOAD ...
DNA breaking-rejoining enzymes. Timeline for Fold d.163: DNA breaking-rejoining enzymes: *Fold d.163: DNA breaking-rejoining ... Fold d.163: DNA breaking-rejoining enzymes appears in SCOP 1.71. *Fold d.163: DNA breaking-rejoining enzymes appears in SCOP ... Fold d.163: DNA breaking-rejoining enzymes [56348] (1 superfamily). core: alpha3-beta3-alpha4; one side of beta-sheet is ... Lineage for Fold d.163: DNA breaking-rejoining enzymes. *Root: SCOP 1.73 *. Class d: Alpha and beta proteins (a+b) [53931] (334 ...
... ... Breaking: Dodge Viper Done By July 2010, Coming Back In 2012 With Fiat Group DNA. ... And best of all, perhaps, is that it will leverage some of Fiats sportscar DNA. In an oblique reference, Gilles mentioned ...
Project Summary/Abstract As the most common form of DNA lesions, DNA single-strand breaks (SSBs) are derived from environmental ... Whereas it is widely accepted that ATM is essential for the repair and signaling of DNA double-strand breaks (DSBs), it remains ... Our substantial preliminary data using biochemical, structure and function analyses suggest that ATM- mediated DNA damage ... toxins and chemotherapy drugs as well as endogenous resources such as intermediate DNA repair products in oxidative stress, and ...
The Role of DNA Breaks in Genomic Instability ... DNA Repair Interest Group. Author:. Dr. Andre Nussenzweig, NCI ... The DNA Repair Interest Group is concerned with all forms of DNA damage and repair. As a major defense against environmental ... The members of the DNA Repair Interest Group perform research in areas including DNA repair enzymology and fine structure, ... damage to cells DNA repair is present in all organisms examined including bacteria, yeast, drosophila, fish, amphibians, ...
Among the most deleterious types of DNA damage are DNA double-strand breaks (DSBs), which can cause cell lethality if ... In response to DNA DSBs, cells activate a complex DNA damage checkpoint (DDC) response th … ... Cells confront DNA damage in every cell cycle. ... Keywords: DNA double-strand break; DNA repair; cell cycle; ... Cells confront DNA damage in every cell cycle. Among the most deleterious types of DNA damage are DNA double-strand breaks ( ...
... promotes the repair of breaks in DNA that occur on aging. (Ten previous MindBlog posts on resveratrol can be retrieved by ...
You have, when I not had to Get it, it sent now one a histone h3k36 chromatin switch coordinates dna double strand break repair ... By meaning to create the a histone h3k36 chromatin switch coordinates dna double strand break repair you have to our side of ... It has entered on the a histone h3k36 chromatin switch coordinates dna double strand break repair that the free F consists for ... In a a histone h3k36 chromatin switch coordinates dna double strand break repair, the experts of question is a high flood: it ...
53BP1 limits the formation of recombinogenic single-strand DNA (ssDNA) in BRCA1-deficient cells, leading to defects in ... repair choice is greatly influenced by the initial processing of DNA ends. ... Role of 53BP1 in end protection and DNA synthesis at DNA breaks Jacob Paiano # 1 , Nicholas Zolnerowich # 1 , Wei Wu 1 , ... Role of 53BP1 in end protection and DNA synthesis at DNA breaks Jacob Paiano et al. Genes Dev. 2021. . ...
Aaron Paul Jesse Pinkman Breaking Bad/El Camino Signed Autographed PSA/DNA Coa , Entertainment Memorabilia, Autographs-Original ... Aaron Paul Jesse Pinkman Breaking Bad/El Camino Signed Autographed PSA/DNA Coa. ...
... locus phosphoproteomics reveals phosphorylation of RPA-1 is required for generation of single-strand DNA following a break at a ... locus phosphoproteomics reveals phosphorylation of RPA-1 is required for generation of single-strand DNA following a break at a ... locus phosphoproteomics reveals phosphorylation of RPA-1 is required for generation of single-strand DNA following a break at a ... locus phosphoproteomics reveals phosphorylation of RPA-1 is required for generation of single-strand DNA following a break at a ...
Animals, BRCA1 Protein, Cell Nucleus, Chromatin, DNA Breaks, Double-Stranded, DNA Repair, DNA-Binding Proteins, Genomic ... DNA double-strand breaks (DSBs) are among the most cytotoxic types of DNA damage, which if left unrepaired can lead to ... Assembly and function of DNA double-strand break repair foci in mammalian cells. Research output: Contribution to journal › ... Despite such advances, however, our understanding of the biological relevance of such DNA repair foci still remains limited. In ...
Breaking Taboo, Swedish Scientist Seeks To Edit DNA Of Healthy Human Embryos ... And editing the DNA in embryos is controversial even among people who think human embryonic research is acceptable. Thats the ... The gene-editing tool comprises two molecules that can zero in on individual genes and make very precise changes to the DNA. It ... Chinese scientists triggered an international uproar earlier last year when they tried to edit the DNA of human embryos even ...
... role of CS proteins in DNA break repair by studying histone H2AX phosphorylation in different cell cycle phases and DNA break ... The involvement of CS proteins in the repair of DNA breaks may play an important role in the clinical features of CS patients. ... breaks showed unique features for CS-A and CS-B cells suggesting that these proteins may act at different times along DNA break ... Keywords: Cockayne syndrome; DNA damage; DNA repair; γ-H2AX. Received: September 07, 2017 Accepted: January 19, 2018 Published: ...
Parp1-Xrcc1 and the repair of DNA double strand breaks in male germ cells and Sertoli cells. E. Ahmed1, H. Kal2, P. De Boer3 ... In male germ cells the repair of DNA double strand breaks (DSBs) differs from that described for somatic cell lines due to ... Visualization of complex DNA damage along accelerated ions tracks EPJ Web of Conferences 177, 06002 (2018). ... In conclusion, NHEJ repair of DNA DSBs via the Parp1/Xrcc1 pathway may occur in germ cells and Sertoli cells when homologous ...
Another type of DNA double-strand breaks originates from the DNA heat-sensitive or heat-labile sites. These DNA sites are not ... Reduced expression of DNA repair genes causes deficient DNA repair. When DNA repair is deficient DNA damages remain in cells at ... DNA damage resulting in multiple broken chromosomes. DNA repair is a collection of processes by which a cell identifies and ... Main article: DNA damage theory of aging. Pathological effects of poor DNA repair[edit]. DNA repair rate is an important ...
... the damaged DNA strand invades the undamaged DNA duplex in a process referred to as DNA strand exchange. A DNA polymerase then ... DNA damage DNA REPAIR PATHWAYS Direct Reversal The simplest of the human DNA repair pathways involves the direct reversal of ... binding of the KU heterodimer to double-stranded DNA ends, recruitment of DNA-PKcs (officially known as protein kinase, DNA- ... replication of single-stranded DNA breaks, and mechanical stress on the chromosomes. DSBs differ from most other types of DNA ...
Failure to reseal broken DNA strands results in protein-linked DNA breaks, causing neurodegeneration in humans. This is ... Tyrosyl DNA phosphodiesterase 1 (TDP1) repairs DNA breaks and is mutated in the disease Spinocerebellar Ataxia with Axonal ... and cells carrying a mutation at this residue are inefficient at single-strand DNA break repair. ... While SUMOylation exhibits no impact on TDP1 catalytic activity, it promotes its accumulation at sites of DNA damage. A TDP1 ...
Man who broke into Selena Gomezs home released, arrested again ... Man who broke into Selena Gomezs home released, arrested again ... Known as @lacrimes on Twitter, during almost 30 years at The Times he also has been part of the breaking news staff that won ... A homeless man was arrested twice this week after allegedly breaking into Selena Gomezs home in Calabasas. ...
... plan and will instead play interruption-free with a short ad break before and after each episode. Visit the Hulu Help Center ... Due to streaming rights, a few shows with an ad break before and after. Which shows? ...
The OxiSelect™ DNA Double-Strand Break Staining Kit provides an easy-to-use method for detecting the presence of DSBs in cells ... in DNA are among the most dangerous types of DNA damage occuring within cells. One of the earliest cellular responses to double ... breaks is the phosphorylation of a histone variant, H2AX, at the sites of DNA damage. Within seconds Ser139 is phosphorylated ... Double strand breaks can be detected in just a few hours by immunofluorescence staining of the phosphorylated histone H2AX. ...
EADV Updates Research and Delves Into DNA Behind Dermatology * 2001/viewarticle/933300 ... The third late-breaking trial that warmed the heart of ESC 2003 was SPORTIF III. Advertised as "the largest-ever stroke ... Conference Coverage Tales From The Vienna Congress - Late-Breaking Clinical Trials and Other Considerations ... A substantial number of the presentations were certainly ground-breaking and inspiring, but inevitably there was also a ...
Double strand breaks in DNA resulting from double ionization events. E. Surdutovich1,2a and A.V. Solovyov2,3 ... A mechanism of double strand breaking in DNA due to the action of two electrons is considered. These are the electrons produced ... Multiscale approach to radiation damage induced by ion beams: complex DNA damage and effects of thermal spikes Eur. Phys. J. D ... in the vicinity of DNA molecules due to ionization of water molecules with a consecutive emission of two electrons, making such ...
... can mono-ADP-ribosylate double-stranded DNA ends. ADP-ribosylation of DNA mediated by PARP3 attaches a single mono-ADP-ribose ... We further show that mono ADP-ribosylation at DNA ends can be efficiently reversed by several cellular hydrolases (PARG, ... Here, we show using biochemical studies that PARP3, a DNA damage-activated ADP-ribosyltransferase, ... MACROD2, TARG1 and ARH3). This suggests that mono ADP-ribosylated DNA adducts can be efficiently removed in cells by several ...
San Franciscos District Attorney on Tuesday explained why he believes the citys police officers are comparing DNA from rape ... kits to unknown DNA left behind by suspects at crime scenes. ... BREAKING NEWS. Breaking news delivered fast. By clicking Sign ... s police officers are comparing DNA from rape kits to unknown DNA left behind by suspects at crime scenes. ... One was unknown DNA left by a suspect at a crime that occurred recently. During a routine search of the SFPD crime lab. It goes ...
Break Point trailer out: A tale of Mahesh Bhupati-Leander Paes journey from bromance to break-up". DNA India. 17 September ... "Watch Break Point Web Series, Show Online in HD on ZEE5". Shekhar, Mimansa (1 October 2021). "Break Point: Leander Paes, Mahesh ... Break Point on ZEE5 Break Point at IMDb (CS1 errors: generic name, Articles with short description, Short description matches ... "Break Point: Mahesh Bhupati-Leander Paes series tells their story from bromance to break-up". The Indian Express. 15 ...
  • We were also able to detect spontaneous DSBs within the 70-bp repeats upstream of the actively transcribed VSG gene, indicating that a DSB is a natural intermediate of VSG gene conversion and that VSG switching is the result of the resolution of this DSB by break-induced replication. (nih.gov)
  • DNA double strand breaks (DSBs) have detrimental effects on cell survival and genomic stability, and are related to cancer and other human diseases. (elifesciences.org)
  • Kif2C knockdown or knockout led to accumulation of endogenous DNA damage, DNA damage hypersensitivity, and reduced DSB repair via both NHEJ and HR. Interestingly, Kif2C depletion, or inhibition of its microtubule depolymerase activity, reduced the mobility of DSBs, impaired the formation of DNA damage foci, and decreased the occurrence of foci fusion and resolution. (elifesciences.org)
  • The most deleterious DNA damages are double-strand breaks (DSBs), and a single unrepaired DSB can lead to cell death. (utexas.edu)
  • In U87 and U251 cells, TMZ (200 μM) induced DNA double strand breaks (DSBs) and nuclear translocation of apoptosis inducing factor (AIF), which was accompanied by BNIP3-mediated mitophagy and FOXO3a accumulation in nucleus. (chinaphar.com)
  • TMZ treatment induced intracellular ROS accumulation in U87 and U251 cells via enhancing mitochondrial superoxide, which not only contributed to DNA DSBs and exacerbated mitochondrial dysfunction, but also upregulated FOXO3a expression. (chinaphar.com)
  • Knockdown of FOXO3a aggravated TMZ-induced DNA DSBs and mitochondrial damage, as well as glioma cell death. (chinaphar.com)
  • While these DNA transactions are essential for human fertility and the development of the immune system, misrepaired or unrepaired DNA double-strand breaks (DSBs) can lead to chromosome rearrangements or cell death. (columbia.edu)
  • If NHEJ fails, DSBs may be nucleolytically cleaved to generate 3' single-stranded DNA overhangs via a process called end resection. (columbia.edu)
  • DNA movements can lead to the clustering of DSBs into a common repair focus. (columbia.edu)
  • The OxiSelect™ DNA Double-Strand Break Staining Kit provides an easy-to-use method for detecting the presence of DSBs in cells cultured in microtiter plates. (cellbiolabs.com)
  • DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer. (preprints.org)
  • XRCC4-like factor (XLF)-also known as Cernunnos-has recently been shown to be involved in non-homologous end-joining (NHEJ), which is the main pathway for the repair of DNA double-strand breaks (DSBs) in mammalian cells. (arizona.edu)
  • DNA double-strand breaks (DSBs) trigger ATM (ataxia telangiectasia mutated) signalling and elicit genomic rearrangements and chromosomal fragmentation if misrepaired or unrepaired. (birmingham.ac.uk)
  • The fission yeast Schizosaccharomyces pombe Rec12 protein , the homolog of Spo11 in other organisms, initiates meiotic recombination by creating DNA double-strand breaks (DSBs) and becoming covalently linked to the DNA ends of the break. (bvsalud.org)
  • This protein - DNA linkage has previously been detected only in mutants such as rad50S in which break repair is impeded and DSBs accumulate. (bvsalud.org)
  • These results confirm our earlier findings describing the occurrence of widely spaced DSBs primarily in large intergenic regions of DNA and demonstrate the relevance and usefulness of fission yeast studies employing rad50S. (bvsalud.org)
  • The ataxia telangiectasia Rad3-related (ATR) protein responds to UV damage, whereas the ataxia telangiectasia mutated (ATM) protein responds to double-strand breaks (DSBs) caused by ionizing radiation and radiomimetic compounds. (medscape.com)
  • Using the SURVEYOR nuclease assay 13 , we assessed the ability of each Cas9-sgRNA complex to generate indels in human embryonic kidney (HEK) 293FT cells through the induction of DNA doublestranded breaks (DSBs) and subsequent nonhomologous end joining (NHEJ) DNA damage repair (Online Methods). (cdc.gov)
  • Researchers find that temporary double-stranded DNA breaks commonly result from normal neuron activation-but expression of an Alzheimer's-linked protein increases the damage. (the-scientist.com)
  • Because of these limited therapeutic targets, many cancers, including TNBCs, are typically treated with surgery and a combination of radiation and chemotherapy that induce various types of DNA damage. (sciencedaily.com)
  • Collectively, our study provides new insight into the DNA damage repair pathway, long non-coding RNAs, and triple-negative breast cancer. (sciencedaily.com)
  • and Richard Sherwood of Brigham and Women's Hospital-suggests that the cell's own repair mechanisms could one day be combined with CRISPR-based therapies that correct gene mutations by simply cutting DNA precisely and allowing the cell to naturally heal the damage ( https://doi.org/10.1038/s41586-018-0686-x ). (bio-itworld.com)
  • We speculate that these effects could result from a direct effect of radiofrequency electromagnetic energy on DNA molecules and/or impairment of DNA-damage repair mechanisms in brain cells. (nih.gov)
  • The recruitment of Kif2C to DNA damage sites was dependent on both PARP and ATM activities. (elifesciences.org)
  • Taken together, our study established Kif2C as a new player of the DNA damage response, and presented a new mechanism that governs DSB dynamics and repair. (elifesciences.org)
  • DNA damage is ubiquitous to all organisms and very complex pathways have evolved to recognize and repair these lesions. (utexas.edu)
  • However, tumor cells can tolerate otherwise lethal levels of DNA damage by exploiting DNA repair pathways. (columbia.edu)
  • Following DNA damage, repair factors accumulate at DSB sites and form microscopically-detectable DNA repair foci. (columbia.edu)
  • We demonstrated that 2-ME increased nuclear localization of neuronal nitric oxide synthase, resulting in nitro-oxidative DNA damage. (oncotarget.com)
  • Each time we learn something new, our brain cells break their DNA, creating damage that the neurons must immediately repair, according to Dr. Li-Huei Tsai, the Picower Professor of Neuroscience and Director of the Picower Institute for Learning and Memory at MIT. (bioquicknews.com)
  • However, as we age, our cells' ability to repair this DNA damage weakens, leading to degeneration, Dr. Tsai says. (bioquicknews.com)
  • When we are young, our brains create DNA breaks as we learn new things, but our cells are absolutely on top of this and can quickly repair the damage to maintain the functionality of the system," Dr. Tsai says. (bioquicknews.com)
  • Evolutionary selection ensures specificity and efficiency in dynamic metastable macromolecular machines that repair DNA damage without releasing toxic and mutagenic intermediates. (escholarship.org)
  • Double-strand breaks ( DSB ) in DNA are among the most dangerous types of DNA damage occuring within cells. (cellbiolabs.com)
  • One of the earliest cellular responses to double-strand breaks is the phosphorylation of a histone variant, H2AX , at the sites of DNA damage. (cellbiolabs.com)
  • Phosphorylation of this serine residue causes chromatin condensation and appears to play a critical role in the recruitment of repair or damage-signaling factors to the DNA damage sites. (cellbiolabs.com)
  • Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated. (preprints.org)
  • Excluding 53BP1 from chromatin is required to attenuate the DNA damage response during mitosis, yet the functional relevance and regulation of this exclusion are unclear. (ewha.ac.kr)
  • Ctp1 is a first responder to DNA damage, but the molecular nature of the Ctp1-DNA interaction was unknown," he said. (nih.gov)
  • To maintain the integrity of the genome, cells evolved complex mechanisms to detect DNA damage, signal its presence, and guide its repair. (nih.gov)
  • DNA strand breaks, oxidative damage, and 1-OH pyrene in roofers with coal-tar pitch dust and/or asphalt fume exposure. (cdc.gov)
  • OBJECTIVE: To determine the potential for asphalt fume exposure to increase DNA damage, we conducted a cross-sectional study of roofers involved in the application of roofing asphalt. (cdc.gov)
  • Significant changes in DNA damage appeared to be linked to PACs from coal-tar exposure, although asphalt fume alone was associated with a small but significant increase in urinary 1-OH-pyrene and DNA strand breaks. (cdc.gov)
  • CONCLUSIONS: Results are consistent with previous reports that asphalt or coal-tar exposure can cause DNA damage. (cdc.gov)
  • The increase in urinary 8OHdG coupled with the decrease in leukocyte 8-OHdG/dG, suggests that coal-tar exposure induces protective or repair mechanisms that result in reduced levels of steady-state oxidative-DNA damage. (cdc.gov)
  • Acetaldehyde damages your DNA and prevents your body from repairing the damage. (cdc.gov)
  • We hypothesized that DA WT cells might undergo changes, such as acquiring a persistent tolerance to DNA damage and copy number aberrations (CNAs), which could eventually lead to their resistance to chemotherapy treatment. (lu.se)
  • These ROS cause much used was 7,12-dmethylbenz[a]anthracene (DMBA), DNA damage each day n each cell (Burkart et al. (who.int)
  • Mutatons caused by genotoxc agents general y damage) and many other types of DNA damage. (who.int)
  • The amount of DNA damage caused each day s appled. (who.int)
  • The two repair scaffold proteins, Ku80 and DNA-PKcs, that LINP1 links coordinate the non-homologous end-joining (NHEJ) repair molecules that fix double-strand breaks in DNA. (sciencedaily.com)
  • The NHEJ pathway, which repairs double-strand breaks in DNA, is one of the major pathways in tumor cells that respond to radiation treatment and chemotherapeutic agents. (sciencedaily.com)
  • Inhibition of the NHEJ pathway has been proposed by oncology researchers to synergize DNA-damaging therapies for better treatment outcomes for TNBCs. (sciencedaily.com)
  • In human cells, there exist two canonical pathways of DSB repair: Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR). Two protein complexes that rapidly bind DNA ends coordinate these separate pathways: the Ku70-Ku80 heterodimer (Ku) and the Mre11-Rad50-Nbs1 complex (MRN), respectively. (utexas.edu)
  • The resected DNA strands are poor substrates for NHEJ and instead search for homology in the genome to resynthesize the sequence surrounding the break site. (columbia.edu)
  • The dynamics of these foci may be observed by time-lapse microscopy making it possible to observe the behavior of breaks undergoing HDR and NHEJ. (columbia.edu)
  • In this chapter, I also investigate how Arp2/3-driven DSB movements specifically promote the dynamics of HDR breaks, while Arp2/3 activity does not influence NHEJ breaks. (columbia.edu)
  • Here we examine non-homologous end joining (NHEJ) as the primary conserved DNA double-strand break (DSB) repair process in human cells. (escholarship.org)
  • Upon binding two DNA ends, auto-phosphorylation opens DNA-PKcs dimer licensing NHEJ via concerted conformational transformations of XLF-XRCC4, XLF-Ku80, and LigIV BRCT -Ku70 interfaces. (escholarship.org)
  • In this study, we identified microtubule-depolymerizing kinesin Kif2C as a protein associated with DSB-mimicking DNA templates and known DSB repair proteins in Xenopus egg extracts and mammalian cells. (elifesciences.org)
  • In contrast, MRN along with the long-range nuclease Exo1 and helicase BLM digests the DNA to create long 3' single-stranded DNA overhangs, which are rapidly bound by the single-stranded DNA binding protein RPA. (utexas.edu)
  • During meiosis proteins Red1 and Hop1 form a protein:DNA (coloured black) axis together with cohesin (not shown for clarity). (elifesciences.org)
  • In the long-range synaptic complex, X-ray repair cross-complementing 4 (XRCC4) plus XRCC4-like-factor (XLF) form a flexible bridge and linchpin for DNA ends bound to KU heterodimer (Ku70/80) and DNA-PKcs (DNA-dependent protein kinase catalytic subunit). (escholarship.org)
  • NIEHS scientists and colleagues discovered how the protein Ctp1 helps repair DNA double-strand breaks, which may shed light on certain genetic diseases. (nih.gov)
  • A protein called Ctp1 mediates the repair of DNA double-strand breaks by forming filaments that bridge two DNA strands, according to a study in yeast by NIEHS researchers and their colleagues at the University of North Carolina at Chapel Hill (UNC). (nih.gov)
  • This work provides the first molecular snapshot of the Ctp1 protein bound to DNA. (nih.gov)
  • A model for the Ctp1-DNA bridging filament is depicted as orange Ctp1 protein tetramers bound to silver DNA strands, shown on a blue background of atomic force imaging. (nih.gov)
  • While it was bound to double-stranded DNA, Ctp1 clustered into tetramers, or protein complexes consisting of four subunits. (nih.gov)
  • Protein-DNA filaments are an architectural feature frequently found to regulate genomic structure and repair," Williams noted. (nih.gov)
  • Chromatin is the complex of DNA and protein that packages DNA into chromosomes. (medlineplus.gov)
  • A DNA-binding protein that mediates DNA REPAIR of double strand breaks, and HOMOLOGOUS RECOMBINATION. (bvsalud.org)
  • This molecule enhances the repair of DNA breaks by serving as a scaffold that links two other proteins in the repair machinery. (sciencedaily.com)
  • Through a technique known as DNA origami, scientists have created the fastest, most persistent DNA nano motor yet. (engineersireland.ie)
  • This area of biotechnology research, known as DNA origami, folds DNA into nano-scale shapes designed to perform specific mechanical functions or biological interactions. (thebulletin.org)
  • Loops of chromatin are extruded from the axis, where DNA breaks are made by the Spo11 complex (pale magenta). (elifesciences.org)
  • We recall that the latter involves driving a DNA filament through a pore so narrow that only one of the double-helical strands can pass, while the other strand is left behind. (nanowerk.com)
  • By moving around the sequence of letters on the strands, researchers can get the DNA strands to bind together in ways that create different shapes. (engineersireland.ie)
  • The rod, or 'chassis' of the motor consists of 16 DNA strands bound together in a four-by-four stack to form a beam with four flat sides. (engineersireland.ie)
  • A single string of DNA can fold into all kinds of intricate shapes-depending on the base sequence encoded in the staple strands. (thebulletin.org)
  • And because researchers were focused on designing structures from scratch, it was necessary to create purified DNA strands. (thebulletin.org)
  • Our DNA strands are continuously broken through intrinsic cellular DNA processes, and through environmental exposures to DNA-damaging radiation and chemotherapeutic drugs," said senior study author Scott Williams, Ph.D. , deputy chief of the NIEHS Genome Integrity and Structural Biology Laboratory. (nih.gov)
  • We knew that Ctp1 could bind DNA and bridge two strands together, but we didn't know how," Williams explained. (nih.gov)
  • Interestingly, in yeast and mammalian cells, DNA motion is increased following DSB generation. (columbia.edu)
  • X-ray scattering reveals disordered linkers and dynamic interfaces in complexes and mechanisms for DNA double-strand break repair impacting cell and cancer biology. (escholarship.org)
  • The disorders are characterized by a defect in DNA repair mechanisms or genomic stability, and patients with these disorders show increased predisposition to cancer. (medscape.com)
  • Here we demonstrate that the introduction of a DNA double-stranded break (DSB) adjacent to the approximately 70-base-pair (bp) repeats upstream of the transcribed VSG gene increases switching in vitro approximately 250-fold, producing switched clones with a frequency and features similar to those generated early in an infection. (nih.gov)
  • Here we describe prime editing, a versatile and precise genome editing method that directly writes new genetic information into a specified DNA site using a catalytically impaired Cas9 endonuclease fused to an engineered reverse transcriptase, programmed with a prime editing guide RNA (pegRNA) that both specifies the target site and encodes the desired edit. (nature.com)
  • They break plants apart to a genetic level and put the pieces back together to build a "reference genome. (alfafarmers.org)
  • While it has human nuclear DNA within its genome, there are also distinctly non-human, non-archaic hominin, and non-ape sequences. (yahoo.com)
  • cerevisiae, genome -wide microarray analysis of Rec12- DNA reveals indistinguishable meiotic DSB distributions in rad50(+) and rad50S strains of Sc. (bvsalud.org)
  • One of the biggest challenges of DNA motors is the fact that rules governing motion at the nanoscale are different than those for objects that humans can see. (engineersireland.ie)
  • The male progenitor that contributed the unknown sequence to this hybrid is unique as its DNA is more distantly removed from humans than other recently discovered hominins like the Denisovan individual," explains Ketchum. (yahoo.com)
  • The findings , published in the March 1 issue of the Journal of Biological Chemistry, could provide insight into the DNA repair defect that causes Seckel and Jawad syndromes in humans. (nih.gov)
  • We believe that the DNA binding and bridging activity of Ctp1 has likely been conserved in evolution and plays a similar role in humans," Williams said. (nih.gov)
  • breaks among cattle and humans in Brazil. (cdc.gov)
  • We performed more than 175 edits in human cells, including targeted insertions, deletions, and all 12 types of point mutation, without requiring double-strand breaks or donor DNA templates. (nature.com)
  • Fig. 2: Prime editing of genomic DNA in human cells by PE1 and PE2. (nature.com)
  • In a study published yesterday in Nature , researchers created a machine-learning model-inDelphi-that predicts how human and mouse cells will respond to CRISPR-induced breaks in DNA. (bio-itworld.com)
  • The team discovered that cells often repair broken genes in ways that are precise and predictable, sometimes even returning mutated genes back to their healthy version. (bio-itworld.com)
  • To make sense of it, Sherwood and his colleagues constructed a library of 2,000 Cas9 guide RNAs (gRNAs) paired with DNA target sites, and they observed how cells repaired the breaks at each of the 2,000 sites. (bio-itworld.com)
  • We investigated the effects of acute (2-h) exposure to pulsed (2-micros pulse width, 500 pulses s(-1)) and continuous wave 2450-MHz radiofrequency electromagnetic radiation on DNA strand breaks in brain cells of rat. (nih.gov)
  • Single- and double-strand DNA breaks in individual brain cells were measured at 4h post-exposure using a microgel electrophoresis assay. (nih.gov)
  • These results demonstrate that FOXO3a attenuates temozolomide-induced DNA double strand breaks in human glioma cells via promoting BNIP3-mediated mitophagy. (chinaphar.com)
  • Cells physiologically break their DNA to allow certain important genes to be expressed," Dr. Tsai says. (bioquicknews.com)
  • DNA Double-Strand Break Formation in A549 Cells. (cellbiolabs.com)
  • BCNU-treated UWR2 and UWR3 cells showed a significant BCNU dose-dependent increase in radiation-induced DNA-SSBs at 6 hrs post-drug treatment, and at 100 microM BCNU DNA-ISC was completely masked in UWR2 cells. (duke.edu)
  • We provide evidence that the synergism between BCNU and radiation in the generation of DNA-SSBs is the result of low DNA-SSB repair capacity of the cells, and is further potentiated by the carbamoylating action of BCNU. (duke.edu)
  • Moreover, mutations that changed the DNA bridging made cells especially sensitive to radiation and chemicals that produce double-strand breaks. (nih.gov)
  • Your DNA can also affect how quickly some drugs are removed from the cells in which they act. (cdc.gov)
  • In conclusion, we suggest that chemoresistance of DA WTs may be partly explained by a high proliferative capability of anaplastic cells, which also have a high burden of double-stranded DNA breaks and CNAs, and that there is a gradual emergence of anaplasia in WT. (lu.se)
  • Ectopic recruitment of 53BP1-T1609A/S1618A to mitotic DNA lesions was associated with significant mitotic defects that could bereversed by inhibiting nonhomologous end-joining. (ewha.ac.kr)
  • Nanowerk News ) Reconstructing accurately how the parts of a complex molecular are held together knowing only how the molecule distorts and breaks up. (nanowerk.com)
  • Thus researchers can predict, with reasonably good success, the shapes into which a DNA molecule of a given sequence will fold. (thebulletin.org)
  • An increase in both types of DNA strand breaks was observed after exposure to either the pulsed or continuous-wave radiation, No significant difference was observed between the effects of the two forms of radiation. (nih.gov)
  • Our data further support the results of earlier in vitro and in vivo studies showing effects of radiofrequency electromagnetic radiation on DNA. (nih.gov)
  • Although most DSB repair is ATM-independent, approximately 15% of ionizing radiation (IR)-induced breaks persist in the absence of ATM-signalling. (birmingham.ac.uk)
  • The production of DNA interstrand crosslinks (ISC) by BCNU and other bifunctional alkylators and the effects of these drugs on the repair of radiation-induced DNA-single strand breaks (SSB) were studied in two human glioblastoma used to assess both DNA-ISCs and DNA-SSBs. (duke.edu)
  • There was no enhancement of radiation-induced DNA-SSBs in both cell lines after treatment with cis-DDP, CHZ, or MNU. (duke.edu)
  • A new genetic sensor called PRISM makes use of a host cell's DNA replication machinery to trigger fluorescence in neurons with damaged DNA. (the-scientist.com)
  • In addition, scientists may also use the site to confirm the efficiency of DNA cuts intended to turn genes off, or to determine the end-joining byproducts of a template-driven repair. (bio-itworld.com)
  • The Cell article is titled "Activity-Induced DNA Breaks Govern the Expression of Neuronal Early-Response Genes. (bioquicknews.com)
  • In the case of neurons, they need to break their DNA to enable the expression of early-response genes, which ultimately pave the way for the transcriptional program that supports learning and memory, and many other behaviors. (bioquicknews.com)
  • While the exact size of the deletion varies among affected individuals, most are missing a sequence of about 500,000 DNA building blocks (base pairs) containing several genes. (medlineplus.gov)
  • the resulting piece of DNA is reversed and reinserted into the chromosome. (medlineplus.gov)
  • Indistinguishable landscapes of meiotic DNA breaks in rad50+ and rad50S strains of fission yeast revealed by a novel rad50+ recombination intermediate. (bvsalud.org)
  • A new tool called PRISM draws on virus-host interactions and a DNA repair pathway to help researchers visualize how cellular stress may contribute to neurodegenerative disease. (the-scientist.com)
  • These filaments bridged two double-stranded DNA molecules. (nih.gov)
  • DNA Breaks" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (ouhsc.edu)
  • Scholars@Duke publication: DNA interstrand crosslinking and strand break repair in human glioma cell lines of varying [1,3-bis(2-chloroethyl)-1-nitrosourea] resistance. (duke.edu)
  • The research team used a cluster of computers to simulate the translocation of DNA through nanopores with different driving forces keeping track of the DNA's unzipping speed, a type of data that has rarely been studied despite being directly accessible in experiments Researchers were able to work "backwards", using the information on the speed to accurately reconstruct the thermodynamics of the formation and rupture of the double-helix structure. (nanowerk.com)
  • The technique adopted in the study is general, and thus the researchers expect to be able to extend it beyond DNA to other molecular systems that are still relatively unexplored. (nanowerk.com)
  • The Emory researchers solved these problems by designing a rod-shaped DNA motor that rolls. (engineersireland.ie)
  • Their data will help other researchers and breeders discover the DNA building blocks that give certain plants desirable traits, such as disease resistance or drought tolerance. (alfafarmers.org)
  • In a seemingly unrelated area of technology, researchers are designing and building machines out of DNA-at a scale one thousand times smaller than a human hair. (thebulletin.org)
  • Since the discovery of the DNA double helix 65 years ago, researchers have developed a detailed understanding of this molecular-scale building material and its properties. (thebulletin.org)
  • In the journal RSC Advances, they present the basic idea: while the DNA waves occur in two types (LEFT and RIGHT) for arrays with round pillars, breaking the lateral symmetry in the shape of the pillars, the researchers only see one of the types (LEFT or RIGHT). (lu.se)
  • Rothemund designed DNA staples that would bind to specific points along the "scaffold" strand of a virus. (thebulletin.org)
  • I summarize all of these findings in Chapter 3 and discuss their implications for DNA repair, translocation formation, and clinical applications. (columbia.edu)
  • To fuel its motion, the motor is placed on a track of RNA, a nucleic acid with base pairs that are complementary to DNA base pairs. (engineersireland.ie)
  • Base pairs are the building blocks of the DNA double helix. (nih.gov)
  • Furthermore, under some conditions, instead of the chaotic turbulence, the result is large-scale waves in the form of cyclic spatial and temporal concentration variations, as has been shown for macromolecular DNA flowing in microfluidic pillar arrays. (lu.se)
  • VSG switching is thought to occur predominantly through gene conversion, a form of homologous recombination initiated by a DNA lesion that is used by other pathogens (for example, Candida albicans, Borrelia sp. (nih.gov)
  • Severing the DNA double helix is a requisite step in the exchange of genetic material between homologous chromosomes in meiosis and between immunoglobulin domains during the generation of immune-receptor diversity. (columbia.edu)
  • Combine such machinery with photonic sensors, electric circuits, and complex motion and dynamics, and you are well on your way to a nanorobot made from DNA-a nanorobot that not only mimics mechanical functions but also interacts with biological materials. (thebulletin.org)
  • DNA is the cell's "instruction manual" that controls a cell's normal growth and function. (cdc.gov)
  • An enzyme that targets only RNA that is bound to DNA then quickly destroys the bound RNA. (engineersireland.ie)
  • We were surprised by how nicely the symmetry break of the pillars on the micrometer scale was reflected in the overall behavior of the waves on the millimeter scale," says Jonas Tegenfeldt. (lu.se)
  • We can thus control the behavior of the DNA waves on the millimeter scale by changing details on the 10μm scale in the array," says Jonas Tegenfeldt. (lu.se)
  • Title: Versatile Association Behavior in Mixtures of Oppositely Charged Amphiphiles: From DNA-Like Assembly of Supramolecular Helices to Coacervation in Chiral Surfactant Systems. (lu.se)
  • The rolling DNA motor forges a persistent path, so it continues to move in a straight line, as opposed to the more random motion of walking DNA motors. (engineersireland.ie)
  • In their recently published article, "Using symmetry to control viscoelastic waves in pillar arrays", Professor Jonas Tegenfeldt, Jason P. Beech, Oskar Ström, and Enrico Turato demonstrate waves in a microfluidic channel as a high-contraction DNA solution is pumped through an array of pillars. (lu.se)
  • Our data suggest caution in the use of the standard alkaline elution technique (with 6 hrs between drug exposure and irradiation) to measure BCNU-induced DNA-ISC induction in highly BCNU-resistant cell lines. (duke.edu)
  • Scientists interested in repairing pathogenic mutations can query the site to see where they might be able to cut DNA and get their desired outcomes. (bio-itworld.com)
  • Mutations that prevented Ctp1 from forming multiunit complexes severely impaired DNA bridging. (nih.gov)
  • In particular, the scientists studied how a DNA double helix unzips when translocated at high velocity through a nanopore, reconstructing fundamental DNA thermodynamic properties from the sole speed of the process. (nanowerk.com)
  • Scientists in the U.S. claim to have sequenced the DNA of Bigfoot - and found he is a relative of the human race. (yahoo.com)
  • The "calving" event, as scientists call the break, will take place within "days, hours or weeks," the MIDAS Project predicted on Wednesday . (motherjones.com)
  • Scientists have also begun fashioning tiny machine components by coating DNA objects with plastics and other materials. (thebulletin.org)
  • Scientists knew that Ctp1 plays an important role in repairing DNA double-strand breaks, but until now, the underlying mechanism was unclear, according to Petr Cejka Ph.D., from the Institute for Research in Biomedicine in Switzerland. (nih.gov)
  • All regions were scored for anaplastic features and immunohistochemistry was used to quantify p53 expression, proliferation index (Ki67), and DNA double-strand breaks (γH2AX). (lu.se)
  • Proliferation index and the frequency of DNA double-strand breaks (γH2AX dot expression) increased with higher anaplasia scores. (lu.se)
  • Kosicki, M., Tomberg, K. & Bradley, A. Repair of double-strand breaks induced by CRISPR-Cas9 leads to large deletions and complex rearrangements. (nature.com)
  • The new DNA motor is rod-shaped and uses RNA fuel to roll persistently in a straight line, without human intervention, at speeds up to 100 nanometres per minute. (engineersireland.ie)
  • The rolling motion also adds to the new DNA motor's speed: it can travel the length of a human stem cell within two or three hours. (engineersireland.ie)
  • While Schmutz and Grimwood study plants at the non-profit research institute, another division of HudsonAlpha focuses on human DNA research and discovering links to human diseases. (alfafarmers.org)
  • Yale neurologist Dr. Steven Novella says the samples may be contaminated samples of normal, human DNA. (yahoo.com)
  • Human DNA plus some anomalies or unknowns does not equal an impossible human-ape hybrid. (yahoo.com)
  • It equals human DNA plus some anomalies. (yahoo.com)
  • Ku encircles the DNA ends and recruits other factors, such the kinase DNA-PKcs, to bluntly ligate the ends back together. (utexas.edu)
  • Then, once it reaches the end, MRN removes DNA-PK and recruits Exo1 and BLM in order to promote long-range digestion of the DNA. (utexas.edu)
  • He explains the significance of breaks in DNA that cell phones are proven to cause, emphasizes the dangers to children, and compares giving kids cell phones to giving them power saws. (buergerwelle.de)
  • When DNA is damaged, a cell can begin growing out of control and create a cancer tumor. (cdc.gov)
  • Importantly, we know from studies that the company has done that the mRNA disintegrates or is broken down by the cell very quickly. (cdc.gov)
  • We find that SpCas9 tolerates mismatches between guide RNA and target DNA at different positions in a sequence-dependent manner, sensitive to the number, position and distribution of mismatches. (cdc.gov)