Environmental factors regulating fish neurohormone genes

神经垂体激素基因在鲑鱼中的表达：硬骨鱼的神经垂体激素被认为是血管催产素(VT)和异催产素(IT)。由于鲑鱼是四倍体，它们通常可能至少有一对蛋白质激素前体基因，包括VT和IT前体基因。因此，我们合成了能够识别这两种mRNAs的反义寡核苷酸作为探针，用原位杂交的方法研究了前神经分泌神经元中前VT基因表达水平的变化，提示VT可能在淡水适应中起了作用。PRO-IT-I的杂交信号强于PRO-IT-II，而VT基因的表达模式因物种不同而不同。这些信息对分析鲑鱼激素基因表达的调控机制非常重要。腺垂体激素基因的表达：研究了虹鱼性腺成熟后促性腺激素前体基因水平的变化。此外，还研究了生长激素和催乳素基因在原代培养的虹鳟鱼脑垂体中的表达。

Expression of Neurohypophysial HOrmone Genes in Salmonids :Teleostean neurohypophysial hormones are considered to be vasotocin (VT) and isosotocin (IT). Since salmonids are tetraploid, they may usually have at least a pair of genes for precursors of proteinaceous hormones, including VT and IT precursor genes. Hence antisense oligodeoxynucleotides which can recognize both of 2 types of mRNAs were synthesized as probes for an in situ hybridization study on effects of increase in the level of pro-VT mRNA was found in preotic neurosecretory neurons, suggesting a possible role of VT in fresh water adaptarion.The pattern of expression of 2 pro-VT and 2 pro-IT genes were examined by use of Northern blot analysis in rainbow trout, masu salmon, sockeye salmon and chum salmon. The hybridization signal for pro-IT-I was stronger than that for pro-IT-II in all species examined, whereas the pattern of VT gene expression was different among species. Such information is quite important in a future study to analyze regulatory mechanisms of hormonal gene expression in salmonids.Expression of Adenohypophysial Hormone Genes :Changes in the levels of gonadotropin precursor genes were examined in rainbow trout following gonadal maturation. Expression of genes from growth harmone and prolactin was also examined in pituitaries of rainbow trout in primary culture.