The changes in the concentrations of endogenous hormones and their influence on carbohydrate metabolism in leaves of micropropagated Fuji apple plants were studied under water deficiency stress. The results showed tha...The changes in the concentrations of endogenous hormones and their influence on carbohydrate metabolism in leaves of micropropagated Fuji apple plants were studied under water deficiency stress. The results showed that water stress induced a rapid increase in the concentration of abscisic acid （ABA） and led to a decrease in concentrations of both zeatin and gibberellins （GAs）. The concentration of indole-3-acetic acid （IAA） changed in an independent manner, which was not correlated with the different levels of water stress. With regard to the carbohydrates, the contents of sorbitol and sucrose increased, whereas the content of starch decreased. The increase in the concentration of ABA was significantly correlated with both the increase in the activity of aldose-6-phosphate reductase （A6PR） and the decrease in the activity of sorbitol dehydrogenase （SDH）, indicating that ABA played a regulatory role in sorbitol metabolism. The concentration of ABA was positively correlated to the activity of sucrose-phosphate synthase （SPS） but negatively correlated to the activities of acid invertase （AI） and ADP-glucose-pyrophosphorylase （ADPGppase） in water-stressed plants, which indicated that ABA promoted sucrose synthesis and inhibited sucrose degradation and starch synthesis at the same time. Under conditions of water stress, the decrease in the level of zeatin was accompanied by a decrease in the activities of SDH and ADPGPPase. GAs concentration showed positive correlation with ADPGPPase activity. IAA showed no significant correlation with any of the enzymes tested in this study. The results of this study suggested that ABA might be one of the key factors regulating the distribution of carbohydrates under water stress. The metabolism of sorbitol and starch under conditions of water stress might be regulated by the combined action of many plant hormones.展开更多
细菌分泌系统的发现是近年来细菌致病机制研究的重点。致病菌为在宿主体内生存、繁殖、扩散,会分泌一些蛋白性质的毒性因子。目前认为革兰阴性致病菌在长期进化过程中形成入侵宿主细胞的特异性分泌系统共有5种类型(Ⅰ~Ⅴ型),其中最显著...细菌分泌系统的发现是近年来细菌致病机制研究的重点。致病菌为在宿主体内生存、繁殖、扩散,会分泌一些蛋白性质的毒性因子。目前认为革兰阴性致病菌在长期进化过程中形成入侵宿主细胞的特异性分泌系统共有5种类型(Ⅰ~Ⅴ型),其中最显著的是细菌Ⅲ型分泌系统(type three secretion system,T3SS),与细菌致病性密切相关。T3SS抑制剂的策略是细菌分泌毒力蛋白,阻止其对宿主细胞的侵染。本文对细菌T3SS的组成、T3SS抑制剂筛选系统、T3SS抑制剂以及作用机制等进行综述,为深入研究以T3SS为靶点的药物设计提供参考。展开更多
基金supported by the National Natural Science Foundation of China(39970527)Establishment of High School Subject Groups in Beijing,China(XK1001900553)Program for New Century Excellent Talents in Universities of China.
文摘The changes in the concentrations of endogenous hormones and their influence on carbohydrate metabolism in leaves of micropropagated Fuji apple plants were studied under water deficiency stress. The results showed that water stress induced a rapid increase in the concentration of abscisic acid （ABA） and led to a decrease in concentrations of both zeatin and gibberellins （GAs）. The concentration of indole-3-acetic acid （IAA） changed in an independent manner, which was not correlated with the different levels of water stress. With regard to the carbohydrates, the contents of sorbitol and sucrose increased, whereas the content of starch decreased. The increase in the concentration of ABA was significantly correlated with both the increase in the activity of aldose-6-phosphate reductase （A6PR） and the decrease in the activity of sorbitol dehydrogenase （SDH）, indicating that ABA played a regulatory role in sorbitol metabolism. The concentration of ABA was positively correlated to the activity of sucrose-phosphate synthase （SPS） but negatively correlated to the activities of acid invertase （AI） and ADP-glucose-pyrophosphorylase （ADPGppase） in water-stressed plants, which indicated that ABA promoted sucrose synthesis and inhibited sucrose degradation and starch synthesis at the same time. Under conditions of water stress, the decrease in the level of zeatin was accompanied by a decrease in the activities of SDH and ADPGPPase. GAs concentration showed positive correlation with ADPGPPase activity. IAA showed no significant correlation with any of the enzymes tested in this study. The results of this study suggested that ABA might be one of the key factors regulating the distribution of carbohydrates under water stress. The metabolism of sorbitol and starch under conditions of water stress might be regulated by the combined action of many plant hormones.
文摘细菌分泌系统的发现是近年来细菌致病机制研究的重点。致病菌为在宿主体内生存、繁殖、扩散,会分泌一些蛋白性质的毒性因子。目前认为革兰阴性致病菌在长期进化过程中形成入侵宿主细胞的特异性分泌系统共有5种类型(Ⅰ~Ⅴ型),其中最显著的是细菌Ⅲ型分泌系统(type three secretion system,T3SS),与细菌致病性密切相关。T3SS抑制剂的策略是细菌分泌毒力蛋白,阻止其对宿主细胞的侵染。本文对细菌T3SS的组成、T3SS抑制剂筛选系统、T3SS抑制剂以及作用机制等进行综述,为深入研究以T3SS为靶点的药物设计提供参考。
