Gonadal expression profiles of sex-specific genes during early sexual differentiation in Japanese eel Anguilla japonica

Abstract

The Japanese eel Anguilla japonica is a prominent and highly valued species in the aquaculture industry in Japan. Sex determination and sex differentiation in eels are significantly affected by environmental factors; however, the molecular mechanisms involved in sex differentiation in eels are largely unknown. In this study, to investigate the gonadal expression profiles of sex-specific genes during and after sexual differentiation in Japanese eel, we induced elvers into predominantly phenotypic males or females by rearing on a control diet or estradiol-17β-treated diet, respectively, during the sex differentiation period. Quantitative real-time PCR showed that forkhead box L2A (foxl2a) and cytochrome P450 aromatase (cyp19a1) were more highly expressed in ovaries than in testes, whereas the expression levels of anti-Mullerian hormone (amh) and gonadal soma-derived factor (gsdf) were significantly higher in testes than in ovaries. Furthermore, foxl2a and cyp19a1 displayed female-specific expression early in the sex differentiation process, while after slightly more growth amh and gsdf displayed male-specific expression during sex differentiation. Together, these results suggest that these genes have important roles in sexual differentiation and development in this species.