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131.
Xing Shun Song Chun Lan Tiao Kai Shi Wei Hua Mao Joshua Otieno Ogweno Yan Hong Zhou Jing Quan Yu 《Plant Growth Regulation》2006,49(1):85-93
In order to clarify the response of antioxidant systems in various cellular organelles to photo-oxidative stress, the activities
of superoxide dismutase (SOD) and enzymes of the ascorbate–glutathione (AsA-GSH) cycle were investigated in chloroplasts,
mitochondria and cytosol of cucumber leaves subjected to methyl viologen (MV) treatment. Photo-oxidation by MV resulted in
significant reductions in net photosynthetic rate (Pn) and increases in the ratio of the quantum efficiency of photosystem
II (PSII),
ΦPSII to that of the quantum efficiency of CO2 fixation (ΦCO2), followed by increased activities of SOD, and a general increase of AsA-GSH cycle enzymes in chloroplasts, mitochondria
and cytosol. These increases were however, most significant in chloroplasts. There were also significant increases in dehydroascorbate
(DHA), reduced glutathione (GSH), and oxidized glutathione (GSSG) except that the content of ascorbate (AsA) in chloroplasts
and cytosol was slightly decreased and little effected, respectively. However, GSSG in mitochondria and GSH in cytosol were
little influenced by the MV treatment. The activity of ascorbate oxidase (AO) in these organelles was independent of the MV
treatment while the activity of l-galactono-1,4- lactone dehydrogenase (GLDH) in mitochondria was slightly inhibited by MV treatment. These results indicate
that disturbance of electron transport in chloroplasts by MV influenced the metabolism of whole cell by a crosstalk signaling
system and that the AsA-GSH cycle played a primary role in sustaining the levels of AsA. 相似文献
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134.
Journal of Molecular Modeling - Human sodium-dependent glucose co-transporter 2 (hSGLT2) is a crucial therapeutic target in the treatment of type 2 diabetes. In this study, both comparative... 相似文献
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中国东北样带的梯度分析及其预测 总被引:52,自引:1,他引:52
陆地样带研究已成为国际地圈-生物圈计划(IGBP)全球变化研究的重要手段与热点。中国东北样带(NECT)已被列为IGBP国际全球变化陆地样带之一。该样带在东经112°与130°30'之间沿北纬43°30'设置,长约1600km,是一条中纬度温带以降水为驱动因素的梯度,具有由温带针阔叶混交林向温带草原的3个亚地带——草甸草原、典型草原与荒漠草原过渡的空间系列。该样带上有4个生态实验站。在大量的固定样地、实验调查研究资料与数据的基础上给出了样带的初步梯度分析及在全球变化图景下的预测,包括其地理位置、设置意义、地形地貌、气候梯度、土壤类型、植被类型和土地利用格局,一个遥感数据驱动的模型和NPP模型在整个样带上运行过。今后NECT将在生物地球化学循环(水、C、N、P等与痕量气体CO_2、CH_4等)、生态系统结构、功能与动态、生物多样性、土地利用与土地覆盖、动态全球植被模型(DGVM)以及高分辨率遥感数据应用等方面得到加强,将成为我国全球变化与陆地生态系统(GCTE)与其它IGBP核心项目研究的前沿阵地。 相似文献
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Aurora B kinase (Aurora-B) functions in chromosome segregation and cleavage of polar spindle microtubules. However, its role in cellular senescence remains elusive. Here, we investigated Aurora-B effects on cellular senescence in human fibroblasts and endothelial cells. Aurora-B levels were reduced during replicative senescence and premature senescence by adriamycin. Aurora-B overexpression in old cells partially reversed senescence phenotypes. In contrast, Aurora-B down-regulation accelerated cellular senescence. p53 knockdown but not p16 knockdown inhibited cellular senescence by Aurora-B reduction. These results suggest that Aurora-B might function in the regulation of cellular senescence of human primary cells via a p53-dependent pathway. 相似文献
140.
Medicago truncatula mtpt4 mutants reveal a role for nitrogen in the regulation of arbuscule degeneration in arbuscular mycorrhizal symbiosis 总被引:1,自引:0,他引:1
Javot H Penmetsa RV Breuillin F Bhattarai KK Noar RD Gomez SK Zhang Q Cook DR Harrison MJ 《The Plant journal : for cell and molecular biology》2011,68(6):954-965
Plants acquire essential mineral nutrients such as phosphorus (P) and nitrogen (N) directly from the soil, but the majority of the vascular plants also gain access to these mineral nutrients through endosymbiotic associations with arbuscular mycorrhizal (AM) fungi. In AM symbiosis, the fungi deliver P and N to the root through branched hyphae called arbuscules. Previously we identified MtPT4, a Medicago truncatula phosphate transporter located in the periarbuscular membrane that is essential for symbiotic phosphate transport and for maintenance of the symbiosis. In mtpt4 mutants arbuscule degeneration occurs prematurely and symbiosis fails. Here, we show that premature arbuscule degeneration occurs in mtpt4 mutants even when the fungus has access to carbon from a nurse plant. Thus, carbon limitation is unlikely to be the primary cause of fungal death. Surprisingly, premature arbuscule degeneration is suppressed if mtpt4 mutants are deprived of nitrogen. In mtpt4 mutants with a low N status, arbuscule lifespan does not differ from that of the wild type, colonization of the mtpt4 root system occurs as in the wild type and the fungus completes its life cycle. Sulphur is another essential macronutrient delivered to the plant by the AM fungus; however, suppression of premature arbuscule degeneration does not occur in sulphur-deprived mtpt4 plants. The mtpt4 arbuscule phenotype is strongly correlated with shoot N levels. Analyses of an mtpt4-2 sunn-1 double mutant indicates that SUNN, required for N-mediated autoregulation of nodulation, is not involved. Together, the data reveal an unexpected role for N in the regulation of arbuscule lifespan in AM symbiosis. 相似文献