A discussion of the mechanism of nylon 6, 6 dissolving process using CaCl_2/MeOH as the sol-vent is presented. The calcium chloride forms a complex compound with nylon 6, 6 by breakingthe hydrogen bonds. The melting p...A discussion of the mechanism of nylon 6, 6 dissolving process using CaCl_2/MeOH as the sol-vent is presented. The calcium chloride forms a complex compound with nylon 6, 6 by breakingthe hydrogen bonds. The melting point of the CaCl_2 --nylon 6, 6 complex was found to be reducedby 91K relative to the pure nylon 6, 6 polymer. The role of methanol is somewhat similar to acatalyst. The results demonstrate that the complexation of a Lewis acid (CaCl_2) and a Lewis base(nylon 6, 6) can be used to probe intermolecular interactions such as hydrogen bonding in polymers, to modify the polymer properties and mediate its solubility and processing.展开更多
Although considerable progress has been made in identifying the genes regulating accumulation of hormones that are involved in leaf senescence, only a few studies have focused on natural variations in jasmonates conte...Although considerable progress has been made in identifying the genes regulating accumulation of hormones that are involved in leaf senescence, only a few studies have focused on natural variations in jasmonates content and much less on the underlying genetic basis. Moreover, the epigenetic regulation of jasmonate-mediated leaf senescence remains largely unknown, in this study, we carried out metabolic profiling of a worldwide collection of rice accessions and demonstrated that there are substantial variations in jasmonate levels among these accessions. A subsequent metabolite-based genornewide association study identified candidates for two major quantitative genes （QTGs）, OsPME1 and OsTSD2, affecting the content of jasmonates. Further investigations using a series of relevant mutants and transgenic lines revealed the MeOH-jasmonata cascade plays an important role in regulating leaf senescence. Moreover, we showed that OsSRT1, one of the two Sir2 （silent information regugator 2） homologs in rice, negatively regulates leaf senescence by repressing expression of the biosynthetic genes of this metabolic cascade and at least particiaUy through histone H3K9 deacetylation of OsPME1. Taken together, our results indicate that the MeOH-jasmonates cascade and its epigenetic regulation are crucial for controlling leaf senescence process in rice.展开更多
文摘A discussion of the mechanism of nylon 6, 6 dissolving process using CaCl_2/MeOH as the sol-vent is presented. The calcium chloride forms a complex compound with nylon 6, 6 by breakingthe hydrogen bonds. The melting point of the CaCl_2 --nylon 6, 6 complex was found to be reducedby 91K relative to the pure nylon 6, 6 polymer. The role of methanol is somewhat similar to acatalyst. The results demonstrate that the complexation of a Lewis acid (CaCl_2) and a Lewis base(nylon 6, 6) can be used to probe intermolecular interactions such as hydrogen bonding in polymers, to modify the polymer properties and mediate its solubility and processing.
基金This work was supported by the State Key Program of the National Natural Science Foundation of China （no. 31530052）, the Major State Basic Research Development Program of China （973 Program, no. 2013CB127001）, the National High Technology R＆D Program of China （863 Program, no. 2012AA10A304）, and the Program from Fundamental Research Funds for the Central Universities （no. 2662015PY196）.
文摘Although considerable progress has been made in identifying the genes regulating accumulation of hormones that are involved in leaf senescence, only a few studies have focused on natural variations in jasmonates content and much less on the underlying genetic basis. Moreover, the epigenetic regulation of jasmonate-mediated leaf senescence remains largely unknown, in this study, we carried out metabolic profiling of a worldwide collection of rice accessions and demonstrated that there are substantial variations in jasmonate levels among these accessions. A subsequent metabolite-based genornewide association study identified candidates for two major quantitative genes （QTGs）, OsPME1 and OsTSD2, affecting the content of jasmonates. Further investigations using a series of relevant mutants and transgenic lines revealed the MeOH-jasmonata cascade plays an important role in regulating leaf senescence. Moreover, we showed that OsSRT1, one of the two Sir2 （silent information regugator 2） homologs in rice, negatively regulates leaf senescence by repressing expression of the biosynthetic genes of this metabolic cascade and at least particiaUy through histone H3K9 deacetylation of OsPME1. Taken together, our results indicate that the MeOH-jasmonates cascade and its epigenetic regulation are crucial for controlling leaf senescence process in rice.
