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Antioxidant Metabolism (antioxidant + metabolism)
Selected AbstractsLead Induced Changes in the Growth and Antioxidant Metabolism of the Lead Accumulating and Non-accumulating Ecotypes of Sedum alfrediiJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2008Dan Liu Abstract The phytotoxicity and antioxidative adaptations of lead (Pb) accumulating ecotype (AE) and non-accumulating ecotype (NAE) of Sedum alfredii Hance were investigated under different Pb treatments involving 0, 0.02 mmol/L Pb, 0.1 mmol/L Pb and 0.1 mmol/L Pb/0.1 mmol/L ethylenediaminetetraacetic acid (EDTA) for 6 days. With the increasing Pb level, the Pb concentration in the shoots of AE plants enhanced accordingly, and EDTA supply helped 51% of Pb translocation to shoots of AE compared with those treated with 0.1 mmol/L Pb alone. Moreover, the presence of EDTA alleviated Pb phytotoxicity through changes in plant biomass, root morphology and chlorophyll contents. Lead toxicity induced hydrogen peroxide (H2O2) accumulation and lipid peroxidation in both ecotypes of S. alfredii. The activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POD), ascorbate peroxidase, and dehydroascorbate reductase elevated in both leaves and roots of AE as well as in leaves of NAE with the increasing Pb levels, but SOD and G-POD declined in roots of NAE. Enhancement in glutathione reductase activity was only detected in roots of NAE while a depression in catalase activity was recorded in the leaves of NAE. A significant enhancement in glutathione and ascorbic acid (AsA)levels occurred in both ecotypes exposed to Pb and Pb/EDTA treatment compared with the control, however, the differences between these two treatments were insignificant. The dehydroascorbate (DHA) contents in roots of both ecotypes were 1.41 to 11.22-fold higher than those in leaves, whereas the ratios of AsA to DHA (1.38 to 6.84) in leaves altering more to the reduced AsA form were much higher than those in roots. These results suggested that antioxidative enzymes and antioxidants play an important role in counteracting Pb stress in S. alfredii. [source] UV-induced skin changes due to regular use of commercial sunbedsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2002J. Ruegemer Background/aim: Increased pigmentation and thickening of the epidermis are the most important photoprotective skin reactions induced by ultraviolet (UV) radiation. The present study was designed to find out what changes are induced by regular use of commercial sunbeds twice weekly over a period of 6 weeks. Methods: The parameters analysed were skin pigmentation measured by chromametry, minimal erythema dose (MED) as a parameter of light sensitivity, epidermal thickening as determined by histology, induction of keratinocyte apoptosis as determined by TUNEL staining and antioxidant metabolism as measured by changes of cis - and trans -urocanic acid (UCA) content of the skin. Results: As expected, chromametry confirmed the clinically obvious increased skin pigmentation. However, no increase in MED was observed. In addition, neither epidermal thickening nor sunburn cells were seen. Significant detectable changes in proportion of the UCA isomer content of the UV-exposed skin were seen. The total UCA and cis -UCA content increased significantly between nearly all points of measurement. The amount of trans -UCA first decreased, then increased significantly between the different time points. Conclusion: Our data indicate that sunbed-induced tanning is non-protective, which has to be addressed for persons looking for this effect before planning a stay in a sunny climate. However, sunbed-induced tanning may influence immunological reactions. [source] Effects of chronic elevated ozone concentration on antioxidant capacity, photosynthesis and seed yield of 10 soybean cultivarsPLANT CELL & ENVIRONMENT, Issue 9 2010AMY M. BETZELBERGER ABSTRACT Crops losses to tropospheric ozone (O3) in the United States are estimated to cost $1,3 billion annually. This challenge is expected to increase as O3 concentrations ([O3]) rise over the next half century. This study tested the hypothesis that there is cultivar variation in the antioxidant, photosynthetic and yield response of soybean to growth at elevated [O3]. Ten cultivars of soybean were grown at elevated [O3] from germination through maturity at the Soybean Free Air Concentration Enrichment facility in 2007 and six were grown in 2008. Photosynthetic gas exchange, leaf area index, chlorophyll content, fluorescence and antioxidant capacity were monitored during the growing seasons in order to determine if changes in these parameters could be used to predict the sensitivity of seed yield to elevated [O3]. Doubling background [O3] decreased soybean yields by 17%, but the variation in response among cultivars and years ranged from 8 to 37%. Chlorophyll content and photosynthetic parameters were positively correlated with seed yield, while antioxidant capacity was negatively correlated with photosynthesis and seed yield, suggesting a trade-off between antioxidant metabolism and carbon gain. Exposure response curves indicate that there has not been a significant improvement in soybean tolerance to [O3] in the past 30 years. [source] Transcriptional profiling reveals elevated CO2 and elevated O3 alter resistance of soybean (Glycine max) to Japanese beetles (Popillia japonica)PLANT CELL & ENVIRONMENT, Issue 4 2008CLARE L. CASTEEL ABSTRACT The accumulation of CO2 and O3 in the troposphere alters phytochemistry which in turn influences the interactions between plants and insects. Using microarray analysis of field-grown soybean (Glycine max), we found that the number of transcripts in the leaves affected by herbivory by Japanese beetles (Popillia japonica) was greater when plants were grown under elevated CO2, elevated O3 and the combination of elevated CO2 plus elevated O3 than when grown in ambient atmosphere. The effect of herbivory on transcription diminished strongly with time (<1% of genes were affected by herbivory after 3 weeks), and elevated CO2 interacted more strongly with herbivory than elevated O3. The majority of transcripts affected by elevated O3 were related to antioxidant metabolism. Constitutive levels and the induction by herbivory of key transcripts associated with defence and hormone signalling were down-regulated under elevated CO2; 1-aminocyclopropane-1-carboxylate (ACC) synthase, lipoxygenase (LOX), allene oxide synthase (AOS), allene oxide cyclase (AOC), chalcone synthase (CHS), polyphenol oxidase (PPO) and cysteine protease inhibitor (CystPI) were lower in abundance compared with levels under ambient conditions. By suppressing the ability to mount an effective defence, elevated CO2 may decrease resistance of soybean to herbivory. [source] Distribution, developmental and stress responses of antioxidant metabolism in MalusPLANT CELL & ENVIRONMENT, Issue 10 2004M. W. DAVEY ABSTRACT A comprehensive study was carried out to examine the interactions between the two major hydrophilic antioxidants l -ascorbate (vitamin C, l -AA), and glutathione (, -glutamyl cysteinylglycine, GSH), and other antioxidant pools in tissues of Malus, to identify factors affecting steady-state cellular concentrations. We show that in Malus, each tissue type has a characteristic and different l -AA/GSH ratio and that in fruit, exocarp (epidermal) tissue acclimated to high light has higher l -AA levels but lower GSH levels than shaded (green) areas. Maturing seeds were characterized by the highest concentrations of GSH and a highly oxidized l -AA pool. It is demonstrated that fruit seeds are capable of l -AA biosynthesis, but that this occurs exclusively by means of the Smirnoff,Wheeler pathway. By contrast, foliar tissue was also able to synthesize l -AA using uronic acid substrates. Unlike the fruit of some other plant species however, the remaining fruit tissues are incapable of de novol -AA biosynthesis. The observed differences in the steady-state concentrations of l -AA and GSH and the capacity to withstand stress in fruit, were also independent of the rates of uptake of photosynthate or of l -AA, but were correlated with the protective effect provided by phenolic compounds in these tissues. During development and maturation, l -AA and GSH levels in apple fruit declined steadily while foliar levels remained essentially constant throughout. However there was no apparent relationship between the free sugar contents of the fruit and antioxidant concentrations. [source] | ||||||||||