MOLECULAR ENDOCRINOLOGICAL STUDY ON MECHANISMS OF ARTIFICIAL MATURATION IN FEMALE JAPANESE EEL

1)研究了日本鳗鲡脑垂体GTH Iβ和IIβ亚基mRNA水平在人工成熟过程中的变化。人工成熟处理开始后，Iβ水平立即显著下降，而IIβ水平显著升高。2）卵巢甾体生成机制从日本鳗鲡卵巢中克隆了P450 SCC、P450 c17、P450 arom、3β-HSD和17β-HSD的cDNA。卵巢P450 arom、P450 c17、P450 arom和17β-HSD的mRNA水平在人工成熟过程中逐渐升高，而3β-HSD的mRNA水平在成熟后期有所下降。3）肝脏卵黄原蛋白（VTG）的产生机制4）自然成熟鳗鱼的性成熟机制比较了人工成熟日本鳗鲡（JP）和人工成熟日本鳗鲡（JP）垂体中GTH Iβ和IIβ以及卵巢中多种类固醇生成酶的mRNA水平。和自然成熟的新西兰长鳍鳗（LF）。LF组Iβ水平高于JP组。而其他各因子在JP组均高于LF组。

1) Mechanism of pituitary GTH productionChanges in mRNA levels of GTH Iβ and IIβ subunits in pituitary of Japanese eel were examined during artificial maturation. The level of Iβ dramatically decreased immediately after the start of the treatment of artificial maturation, while the level of IIβdramatically increased. Experiment of pituitary organ culture revealed that estrogen and androgen strongly supressed the expression of Iβ, while they stimulated the expression of IIβ.2) Mechanism of ovarian sterod productioncDNAs of P450scc, P450c17, P450arom, 3β-HSD and 17β-HSD were cloned from Japanese eel ovary. The mRNA levels of ovarian P450scc, P450c17 , P450arom and 17β-HSD gradually increased during artificial maturation although the level of P450arom decreased in final maturation phase, while the level of 3β-HSD did not change.3) Mechanism of liver vitellogenin(VTG) productionThe mRNA levels of VTG1 in liver increased after mid-vitellogenic stage, while the level of VTG2 increased immediately after the start of the treatment of artificial maturation.4) Mechanism of sexual maturation in natural eelThe mRNA levels of GTH Iβ and IIβ in pituitary and various steroidogenic enzymes in ovary were compared between the artificially maturing Japanese eel (JP) and naturally maturing New Zealand longfinned eel (LF). The level of Iβ in LF was higher than that in JP. However, the levels of others were higher in JP than those in LF.