Selenoprotein biosynthesis may not only be affected by the availability of selenium and the transcription rate of pertinent genes but also by the activity of components of the selenocysteine incorporation complex, Sel...Selenoprotein biosynthesis may not only be affected by the availability of selenium and the transcription rate of pertinent genes but also by the activity of components of the selenocysteine incorporation complex, SelA, B, C, or D. Incorporation of selenocysteine into selenoproteins requires a complex co-translational mechanism guaranteeing the correct recoding of the termination codon TGA as selenocysteine codon. A particular tRNASer(Sec) is enzyrnatically transformed by selenophosphate into tRNAsec which recognizes the UGA codon by means of a specific elongation factor (SelB) and a peculiar mRNA secondary structure. Selenophosphate is formed from selenide and ATP by the SelD gene product, selenophosphate synthase (SelD). To further elucidate the biological role of phospholipid hydroperoxide GPx (PHGPx), we transformed cells with a heterologous (pig) PHGPx gene and/or an additional (human) SelD gene and studied the behaviour of these cells under selenium depletion and repletion. Transfection of the endothelial cell line ECV 304 with either PHGPx cDNA or SelD cDNA did not result in a substantial increase of PHGPx activities, independent of selenium supply. However, cells co-trans fected with both, PHGPx and SelD cDNA, expressed significantly higher PHGPx activlty. This effect was much more pronounced under selenium limiting conditions. The enhanced PHGPx activity correlated with two functional pararneters, increased capability to reduce hydroperoxides and less sensitivity against H2O2-induced cytotoxicity. Thus, the ECV cells, stably transfected with PHGPx and SelD cDNA, provide a model to specifically investigate the role of PHGPx in endothelial cell function展开更多
This article examines the reception of Western corporate governance models and standards into the Chinese system of corporate governance. It investigates how China has adapted these models to fit in with its political...This article examines the reception of Western corporate governance models and standards into the Chinese system of corporate governance. It investigates how China has adapted these models to fit in with its political, economic, and cultural norms in relation to its state owned enterprises （SOEs）, a large number of which are now listed in onthe Fortune Global 500 list. Overall, the study highlights that firstly, the importance of culture in the shaping and functioning of human behavior as well as that of institutions, and in their subsequent path dependence; and secondly the limited impact of property rights, minority shareholder rights, and financial markets as arbiters of the destination of investment funds.展开更多
文摘Selenoprotein biosynthesis may not only be affected by the availability of selenium and the transcription rate of pertinent genes but also by the activity of components of the selenocysteine incorporation complex, SelA, B, C, or D. Incorporation of selenocysteine into selenoproteins requires a complex co-translational mechanism guaranteeing the correct recoding of the termination codon TGA as selenocysteine codon. A particular tRNASer(Sec) is enzyrnatically transformed by selenophosphate into tRNAsec which recognizes the UGA codon by means of a specific elongation factor (SelB) and a peculiar mRNA secondary structure. Selenophosphate is formed from selenide and ATP by the SelD gene product, selenophosphate synthase (SelD). To further elucidate the biological role of phospholipid hydroperoxide GPx (PHGPx), we transformed cells with a heterologous (pig) PHGPx gene and/or an additional (human) SelD gene and studied the behaviour of these cells under selenium depletion and repletion. Transfection of the endothelial cell line ECV 304 with either PHGPx cDNA or SelD cDNA did not result in a substantial increase of PHGPx activities, independent of selenium supply. However, cells co-trans fected with both, PHGPx and SelD cDNA, expressed significantly higher PHGPx activlty. This effect was much more pronounced under selenium limiting conditions. The enhanced PHGPx activity correlated with two functional pararneters, increased capability to reduce hydroperoxides and less sensitivity against H2O2-induced cytotoxicity. Thus, the ECV cells, stably transfected with PHGPx and SelD cDNA, provide a model to specifically investigate the role of PHGPx in endothelial cell function
文摘This article examines the reception of Western corporate governance models and standards into the Chinese system of corporate governance. It investigates how China has adapted these models to fit in with its political, economic, and cultural norms in relation to its state owned enterprises （SOEs）, a large number of which are now listed in onthe Fortune Global 500 list. Overall, the study highlights that firstly, the importance of culture in the shaping and functioning of human behavior as well as that of institutions, and in their subsequent path dependence; and secondly the limited impact of property rights, minority shareholder rights, and financial markets as arbiters of the destination of investment funds.
