The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus...The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH)or that of other hormones and factors that modulate its action. Amphibian metamorphosis is obligatorily dependent on TH which can initiate all the diverse physiological manifestations of this postembryonic developmental process(morphogenesis, cell death, re-structuring, etc.) in free-living embryos and larvae of most anurans. This article will first describe the salient features of metamorphosis and its control by TH and other hormones. Emphasis will be laid on the key role played by TH receptor (TR), in particular the phenomenon of TR gene autoinduction, in initiating the developmental action of TH. Finally, it will be argued that the findings on the control of amphibian metamorphosis enhance our understanding of the regulation of postembryonic development by TH in other vertebrate species.展开更多
Protein kinase inhibitor 6-DMAP was used to explore the effect of protein phosphorylation on germinal vesicle breakdown(GVBD) and chromatin/chromosome behavior of mousc oocytes at different stages .Protein phosphoryl...Protein kinase inhibitor 6-DMAP was used to explore the effect of protein phosphorylation on germinal vesicle breakdown(GVBD) and chromatin/chromosome behavior of mousc oocytes at different stages .Protein phosphorylation induced by 6-DMAP-sensitive protein kinases was not required for GVBD 2 hrs after culture. 6-DMAP stimulated transition to interphase in oocytes after GVBD and inhibited extrusion of the first polar body(PB1) and the second polar body(PB2). This drug also induced the reformation of nucleus in metaphase II(M II) oocytes spontaneously,without the release of cortical granules(CGs), a result that is different from the conclusion obtained before.展开更多
文摘The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH)or that of other hormones and factors that modulate its action. Amphibian metamorphosis is obligatorily dependent on TH which can initiate all the diverse physiological manifestations of this postembryonic developmental process(morphogenesis, cell death, re-structuring, etc.) in free-living embryos and larvae of most anurans. This article will first describe the salient features of metamorphosis and its control by TH and other hormones. Emphasis will be laid on the key role played by TH receptor (TR), in particular the phenomenon of TR gene autoinduction, in initiating the developmental action of TH. Finally, it will be argued that the findings on the control of amphibian metamorphosis enhance our understanding of the regulation of postembryonic development by TH in other vertebrate species.
文摘Protein kinase inhibitor 6-DMAP was used to explore the effect of protein phosphorylation on germinal vesicle breakdown(GVBD) and chromatin/chromosome behavior of mousc oocytes at different stages .Protein phosphorylation induced by 6-DMAP-sensitive protein kinases was not required for GVBD 2 hrs after culture. 6-DMAP stimulated transition to interphase in oocytes after GVBD and inhibited extrusion of the first polar body(PB1) and the second polar body(PB2). This drug also induced the reformation of nucleus in metaphase II(M II) oocytes spontaneously,without the release of cortical granules(CGs), a result that is different from the conclusion obtained before.
