Androgen induces gonadal soma derived factor, Gsdf, in XX gonads correlated to sex reversal but not Dmrt1 directly, in the teleost fish, northern medaka (Oryzias sakaizumii)
In the inbred HNI II strain of Oryzias sakaizumii, Dmy and Gsdf are expressed in XY gonads from Stages 35 and 36, respectively, similarly to the inbred Hd rR strain of Oryzias latipes. However, Dmrt1 respectively becomes detectable at Stage 36 and 5 days post hatching (dph) in the two strains. In XX HNI II embryos, 17a methyltestosterone (MT) induces Gsdf mRNA from Stage 36, accompanied by complete sex reversal in all treated individuals (MT, 10 ng/mL) while Dmrt1 mRNA was first detectable at 5 dph. In XX d rR, MT induced Gsdf mRNA expression and sex reversal in only some of the treated individuals. Together, these results suggest the testis differentiation cascade in XY individuals differs between the HNI II and Hd rR strains. In addition, it is suggested that androgen induced XX sex reversal proceeds via an androgen Gsdf Dmrt1 cascade and that Gsdf plays an important role in sex reversal in medaka.
Molecular and Cellular Endocrinology