Molecular mechanisms of sexual plasticity in adult medaka gonads

2014 Fiscal Year Final Research Report

• Project/Area Number: 24370028
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Morphology/Structure
• Research Institution: Ehime University
• Principal Investigator: NAGAHAMA Yoshitaka 愛媛大学, 南予水産研究センター, 特定教員(教授) (50113428)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 雌雄異体魚 / メダカ成魚 / 性的可塑性 / 性転換 / 生殖幹細胞 / 生殖腺体細胞 / エストロゲン / 芳香化酵素阻害剤

Outline of Final Research Achievements

In all gonochoristic vertebrates, the sexual plasticity of the gonads is not retained after the completion of sex differentiation. Here, we studied whether medaka gonads maintain sexual plasticity until adulthood. The depletion of estrogen resulted in a functional female-to-male sex reversal in sexually mature females. The sex-reserved fish showed a typical male pattern of estrogen levels, secondary sex characteristics, and male-like sex behavior. On the other hand, estrogen treatment in adult males undergoing spermatogenesis induced male-to-female sex reversal, producing fertile eggs. In situ hybridization of medaka gonads during female-to-male and male-to-female sex reversals indicated that cysts on the periphery portions of adult gonads are the origins of germ cells and their surrounding somatic cells in the newly formed testicular and ovarian tissues. Gonochoristic fish maintain their sexual plasticity until adulthood and estrogen plays critical roles in maintaing phenotypic sex.

Free Research Field

生殖生物学