Seasonal change in the balance between capacities of RuBP carboxylation and RuBP regeneration affects CO2 response of photosynthesis in Polygonum cuspidatum. (1/18)

The balance between the capacities of RuBP (ribulose-1,5-bisphosphate) carboxylation (V(cmax)) and RuBP regeneration (expressed as the maximum electron transport rate, J(max)) determines the CO(2) dependence of the photosynthetic rate. As it has been suggested that this balance changes depending on the growth temperature, the hypothesis that the seasonal change in air temperature affects the balance and modulates the CO(2) response of photosynthesis was tested. V(cmax) and J(max) were determined in summer and autumn for young and old leaves of Polygonum cuspidatum grown at two CO(2) concentrations (370 and 700 micromol mol(-1)). Elevated CO(2) concentration tended to reduce both V(cmax) and J(max) without changing the J(max):V(cmax) ratio. The seasonal environment, on the other hand, altered the ratio such that the J(max):V(cmax) ratio was higher in autumn leaves than summer leaves. This alternation made the photosynthetic rate more dependent on CO(2) concentration in autumn. Therefore, when photosynthetic rates were compared at growth CO(2) concentration, the stimulation in photosynthetic rate was higher in young-autumn than in young-summer leaves. In old-autumn leaves, the stimulation of photosynthesis brought by a change in the J(max):V(cmax) ratio was partly offset by accelerated leaf senescence under elevated CO(2). Across the two seasons and the two CO(2) concentrations, V(cmax) was strongly correlated with Rubisco and J(max) with cytochrome f content. These results suggest that seasonal change in climate affects the relative amounts of photosynthetic proteins, which in turn affect the CO(2) response of photosynthesis.  (+info)

Applicability and limitations of optimal biomass allocation models: a test of two species from fertile and infertile habitats. (2/18)

BACKGROUND AND AIMS: The practical applicability of optimal biomass allocation models is not clear. Plants may have constraints in the plasticity of their root : leaf ratio that prevent them from regulating their root : leaf ratio in the optimal manner predicted by the models. The aim of this study was to examine the applicability and limitations of optimal biomass allocation models and to test the assumption that regulation of the root : leaf ratio enables maximization of the relative growth rate (RGR). METHODS: Polygonum cuspidatum from an infertile habitat and Chenopodium album from a fertile habitat were grown under a range of nitrogen availabilities. The biomass allocation, leaf nitrogen concentration (LNC), RGR, net assimilation rate (NAR), and leaf area ratio (LAR) of each species were compared with optimal values determined using an optimal biomass allocation model. KEY RESULTS: The root : leaf ratio of C. album was smaller than the optimal ratio in the low-nitrogen treatment, while it was almost optimal in the high-nitrogen treatment. In contrast, the root : leaf ratio of P. cuspidatum was close to the optimum under both high- and low-nitrogen conditions. Owing to the optimal regulation of the root : leaf ratio, C. album in the high-nitrogen treatment and P. cuspidatum in both treatments had LNC and RGR (with its two components, NAR and LAR) close to their optima. However, in the low-nitrogen treatment, the suboptimal root : leaf ratio of C. album led to a smaller LNC than the optimum, which in turn resulted in a smaller NAR than the optimum and RGR than the theoretical maximum RGR. CONCLUSIONS: The applicability of optimal biomass allocation models is fairly high, although constraints in the plasticity of biomass allocation could prevent optimal regulation of the root : leaf ratio in some species. The assumption that regulation of the root : leaf ratio enables maximization of RGR was supported.  (+info)

Differentiation of rhizoma et radix polygoni cuspidati from closely related herbs by HPLC fingerprinting. (3/18)

An HPLC-DAD fingerprinting profile of Rhizoma Et Radix Polygoni Cuspidati was established basing on the consistent chromatographic features of 24 authentic herb samples. The major types of chemical constituents, stilbenes and anthraquinones, were analyzed and included in the fingerprint. Eight common peaks of Polygonum Cuspidatum were identified by using HPLC-MS. The developed fingerprint was applied to differentiate Rhizoma Et Radix Polygoni Cuspidati from Radix Polygoni Multiflori and Radix Et Rhizoma Rhei. Although the three herbs belong to the family of Polygonaceae, the results indicated that these could be differentiated by using the established method.  (+info)

Antioxidant activity of extract from Polygonum cuspidatum. (4/18)

Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oi Polygonum cuspidatum extract is 110 microg/ml in free radical scavenging assays, 3.2 microg/ml in superoxide radical scavenging assays, and 8 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 +/- 42.6 mg/g and 62.3 +/- 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects.  (+info)

Selective on-line extraction of trans-resveratrol and emodin from Polygonum cuspidatum using molecularly imprinted polymer. (5/18)

High-performance liquid chromatographic separation is performed to extract active components from the traditional Chinese medicine Polygonum cuspidatum using a trans-resveratrol imprinted polymer. Good separation and purification of trans-resveratrol and emodin from the Polygonum cuspidatum extract are achieved after condition optimization. The extraction recoveries are 83% and 99% for trans-resveratol and emodin, respectively. The results show that the molecularly imprinted polymer can be used as a selective extraction material for the extraction and purification of trans-resveratrol and emodin from Polygonum cuspidatum.  (+info)

An antiinflammatory and reactive oxygen species suppressive effects of an extract of Polygonum cuspidatum containing resveratrol. (6/18)

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2-Methoxystypandrone represses RANKL-mediated osteoclastogenesis by down-regulating formation of TRAF6-TAK1 signalling complexes. (7/18)

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Efficient synthesis of natural polyphenolic stilbenes: resveratrol, piceatannol and oxyresveratrol. (8/18)

The practical synthesis of important natural polyphenolic stilbenes, including resveratrol, piceatannol and oxyresveratrol, through Perkin methodology is described. Starting from 3,5-dihydoxyacetophenone (1), the common intermediate 3,5-dimethoxyphenylacetic acid (3) can be obtained via methylation and Willgerodt-Kindler reaction. Perkin condensations between (3) and substituted phenylaldehydes 4 furnished E-2,3-diarylacrylic acids 5, followed by decarboxylation in Cu/quinoline giving stilbene intermediates 6 which bear the Z-configuration. Finally, through a simultaneous demethylation/isomerization process in AlI(3)/CH(3)CN system, the target compounds 7a-c can be obtained respectively in good to high overall yields. The synthetic method proved to be more concise, trans-specific, mild, economical and commonly applicable.  (+info)

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