| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 98 === The objective of this study was to investigate the gene expression
of insulin-like growth factor (IGFs) and their receptors during the sex differentiation and development of the black porgy (Acanthopagrus schlegeli).
Igf-1r, igf-2 and igf-2r were significantly increased at 150 dah, and the expression levels of igf-1 and insr were higher at the 60 dah than the other stages in the gonad of 0+ black porgy (BP). Estradiol (E2) reduced the expression levels of igf-1, igf -1r and igf-2.
However, E2 increased the expression levels of igf-2r and insr. 1,4,6-androstatriene-3,17-dione (ATD，aromatase inhibitor) reduced the expression levels of igf-1, igf-1r, igf-2 and igf-2r. However, there was no significant effect of ATD on the expression of insr. The expression levels of igf-1, igf-1r and igf-2 in testis were higher than ovary of 1+ BP, and igf-2r and insr showed no significant differences in testis and ovary. Igf-1 and igf-1r were significantly increased in testis during the pre-spawning season (from July to September), and igf-2 was significantly increased in testis in October. The expression of igf-1 was significantly increased in testis-excised gonad of 2+ BP in September and January, and the expression levels of igf-1r, igf-2, igf-2r and insr were significantly increased in November. By RNA in situ hybridization, igf-2 was expressed mainly in oogonia and primary oocyte in the gonad of 180 dah juvenile BP, and insr was expressed in the primary oocyte of the ovary of 1+BP. By immunohistochemical stainning, Insr was expressed mainly in germ cells of 150 dah juvenile BP and also in spermatogonia and oogonia of 1+BP gonad at pre-spawning season, Igf-1r was expressed in the follicle cells and spermatogonia of 1+BP at the pre-spawning season and also in the follicle cells of 3+BP at the spawning season.
The results showed that the expressions of igf-1, igf-1r and igf-2 at various developmental stages were significantly different between testis and ovary. E2 and ATD reduced the expression of igf-1, igf-1r and igf-2 in the gonad of 0+ BP, suggesting that E2 and ATD might inhibit the gonadal differentiation and later development. Therefore, igf-1, igf-1r, igf-2,igf-2r and insr might play important roles in the gonadal development and differentiation of BP.
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