Soy Isoflavones Induce Feminization of Japanese Eel (Anguilla japonica)
Hiroyuki Inaba, Yuzo Iwata, Takashi Suzuki, Moemi Horiuchi, Ryohei Surugaya, Shigeho Ijiri, Ai Uchiyama, Ryoko Takano, Seiji Hara, Takashi Yazawa, Takeshi Kitano
Abstract
) produce a high percentage of males. However, females gain higher body weight and have better commercial value than males, and, therefore, a high female ratio is required in eel aquaculture. In this study, we examined the effects of isoflavones, genistein, and daidzein on sex differentiation and sex-specific genes of eels. To investigate the effects of these phytoestrogens on the gonadal sex, we explored the feminizing effects of soy isoflavones, genistein, and daidzein in a dose-dependent manner. The results showed that genistein induced feminization more efficiently than daidzein. To identify the molecular mechanisms of sex-specific genes, we performed a comprehensive expression analysis by quantitative real-time PCR and RNA sequencing. Phenotypic males and females were produced by feeding elvers a normal diet or an estradiol-17β- or genistein-treated diet for 45 days. The results showed that female-specific genes were up-regulated and male-specific genes were down-regulated in the gonads, suggesting that genistein induces feminization by altering the molecular pathways responsible for eel sex differentiation.