The orange-spotted grouper, Epinephelus coioides, is a marine protogynous hermaphrodite fish of commercial importance. There are many examples of sex change species among marine fish, but the molecular basis for the sex change is still unknown. Gonadal expression patterns of the dmrts and foxls genes in E. coioides have pointed to sexual dimorphism in this species and it has been shown that mRNA levels of dmrts and foxls to vary significantly during reproduction cycles. The steroid 17α-methyltestosterone was used to induce sex reversal in these fish, during which dmrts and foxls levels changed significantly and subsequently reverted to normal when 17α-methyltestosterone was withdrawn. Interestingly, the expression of dmrt2b and dmrt3 was not affected by this steroid. We speculate that the role of foxl2 in reproduction may be conserved via regulation of early differentiation of the ovary by the hypothalamus-pituitary-gonad axis, and dmrt2 may have a significant role in premature ovarian differentiation and maintenance in E. coioides. dmrt1 and foxl3 played a role in the development of the testes and are believed to be potential male regulatory genes.
Keywords: Epinephelus coioides; Gene expression; Sex reversal; dmrts; foxl2; foxl3.
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