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31.
The effects of an auxin herbicide, 2,4-D, at a concentration of 0.01 mM, on the K+ uptake and efflux of excised roots of wheat (Triticum aestivum L. cv. Rannaya) were investigated at different pH values. The K+ movement was monitored with a K+ (86Rb) tracer. In parallel experiments the ATPase activities of microsomal fractions were determined by the inorganic phosphate liberation method. 2,4-D inhibited the K+ uptake especially at low pH, irrespective of whether Ca2+ was present or not. No marked changes were observed in the K+ efflux properties at pH values above 4. The inhibitory effect on K+ uptake exhibited a correlation with the hydrocarbon solubility of the herbicide, but not with the 2,4-D-induced decrease of the ATPase activity. It is suggested that 2,4-D exerts a non-specific effect on the lipid-protein interactions, giving rise to a generalized alteration of the transport barrier properties of the plasma membrane even at as low a concentration as 0.01 mM. 相似文献
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It was shown that 2,6-tolyidinonaphthalene sulfonate (2,6-TNS) is localized mainly at the bilayer-water border of the erythrocytic membranes. Under the effect of gamma-radiation the rearrangements occur in the membrane which bring about changes in the distribution of the probe between the membrane and the medium. The lifetime of the excited state of 2,6-TNS after irradiation varies slightly. 相似文献
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小麦族(Triticeae)是禾本科、早熟禾亚科中一个有重要经济价值、以多年生植物占优势的族,族内绝大多数种类是重要的粮食作物和畜牧业上的优良牧草,饲用价值极高,有些种类具有耐寒、耐旱、耐碱等特性,是农牧业上良种繁育、牧草利用的重要基因资源。但该族同时又是分类学上的一个疑难族,各学者对族内系统分类意见不一、争议颇大,尤其在族的界限、族下类群划分以及类群演化关系上问题较多,至今尚未解决。查阅了国内外分类学文献,探讨其分类差异以及存在问题,为充分开发利用中国丰富的小麦族植物资源提供理论依据。 相似文献
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Dung Tien Le Lionel Tarrago Yasuko Watanabe Alaattin Kaya Byung Cheon Lee Uyen Tran Rie Nishiyama Dmitri E. Fomenko Vadim N. Gladyshev Lam-Son Phan Tran 《PloS one》2013,8(6)
Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological conditions. Organisms evolved two distinct methionine sulfoxide reductase families (MSRA & MSRB) to repair oxidized methionine residues. We found that 5 MSRB genes exist in the soybean genome, including GmMSRB1 and two segmentally duplicated gene pairs (GmMSRB2 and GmMSRB5, GmMSRB3 and GmMSRB4). GmMSRB2 and GmMSRB4 proteins showed MSRB activity toward protein-based MetO with either DTT or thioredoxin (TRX) as reductants, whereas GmMSRB1 was active only with DTT. GmMSRB2 had a typical MSRB mechanism with Cys121 and Cys 68 as catalytic and resolving residues, respectively. Surprisingly, this enzyme also possessed the MSRB activity toward free Met-R-O with kinetic parameters similar to those reported for fRMSR from Escherichia coli, an enzyme specific for free Met-R-O. Overexpression of GmMSRB2 or GmMSRB4 in the yeast cytosol supported the growth of the triple MSRA/MSRB/fRMSR (Δ3MSRs) mutant on MetO and protected cells against H2O2-induced stress. Taken together, our data reveal an unexpected diversity of MSRBs in plants and indicate that, in contrast to mammals that cannot reduce free Met-R-O and microorganisms that use fRMSR for this purpose, plants evolved MSRBs for the reduction of both free and protein-based MetO. 相似文献
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LISE COMTE LAËTITIA BUISSON MARTIN DAUFRESNE GAËL GRENOUILLET 《Freshwater Biology》2013,58(4):625-639
1. Climate change could be one of the main threats faced by aquatic ecosystems and freshwater biodiversity. Improved understanding, monitoring and forecasting of its effects are thus crucial for researchers, policy makers and biodiversity managers. 2. Here, we provide a review and some meta‐analyses of the literature reporting both observed and predicted climate‐induced effects on the distribution of freshwater fish. After reviewing three decades of research, we summarise how methods in assessing the effects of climate change have evolved, and whether current knowledge is geographically or taxonomically biased. We conducted multispecies qualitative and quantitative analyses to find out whether the observed responses of freshwater fish to recent changes in climate are consistent with those predicted under future climate scenarios. 3. We highlight the fact that, in recent years, freshwater fish distributions have already been affected by contemporary climate change in ways consistent with anticipated responses under future climate change scenarios: the range of most cold‐water species could be reduced or shift to higher altitude or latitude, whereas that of cool‐ and warm‐water species could expand or contract. 4. Most evidence about the effects of climate change is underpinned by the large number of studies devoted to cold‐water fish species (mainly salmonids). Our knowledge is still incomplete, however, particularly due to taxonomic and geographic biases. 5. Observed and expected responses are well correlated among families, suggesting that model predictions are supported by empirical evidence. The observed effects are of greater magnitude and show higher variability than the predicted effects, however, indicating that other drivers of changes may be interacting with climate and seriously affecting freshwater fish. 6. Finally, we suggest avenues of research required to address current gaps in what we know about the climate‐induced effects on freshwater fish distribution, including (i) the need for more long‐term data analyses, (ii) the assessment of climate‐induced effects at higher levels of organisation (e.g. assemblages), (iii) methodological improvements (e.g. accounting for uncertainty among projections and species’ dispersal abilities, combining both distributional and empirical approaches and including multiple non‐climatic stressors) and (iv) systematic confrontation of observed versus predicted effects across multi‐species assemblages and at several levels of biological organisation (i.e. populations and assemblages). 相似文献
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S. E. Fomenko N. F. Kushnerova V. G. Sprygin T. V. Momot 《Russian Journal of Marine Biology》2016,42(6):509-514
The effects of an extract from the green alga Ulva lactuca and the Essentiale® commercial preparation, which was used as a reference, on the weight indexes of the viscera and the biochemical markers of the liver have been studied in a model of acute stress in rats. Acute stress was simulated by suspending animals in the upright position by their neck dorsal skin fold for 24 hours. Administration of the U. lactuca extract to rats exposed to the extreme stress resulted in a pronounced preventive action, which was manifested in the support of the weight index of their viscera, lipids metabolism, the antioxidant defense system of liver, and a reduction of lipid peroxidation. The extract from U. lactuca was no less effective in protecting the metabolic reactions of the liver under acute stress than the Essentiale® commercial preparation. The pronounced protective properties of the U. lactuca extract are explained by the combined effects of phospholipids of marine origin, n-3 PUFAs, and antioxidant polyphenols that comprise it. 相似文献
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