Spectrum of the sex and the sex reversal by gonads

2021 Fiscal Year Final Research Report

• Project Area: Spectrum of the Sex: a continuity of phenotypes between female and male
• Project/Area Number: 17H06430
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Biological Sciences
• Research Institution: Nagoya University
• Principal Investigator: TANAKA MINORU 名古屋大学, 理学研究科, 教授 (80202175)
• Co-Investigator(Kenkyū-buntansha): 山本 耕裕 大阪医科薬科大学, 医学部, 講師 (20613558)
• Project Period (FY): 2017-06-30 – 2022-03-31
• Keywords: 生殖細胞 / 性決定 / 生殖腺 / メダカ

Outline of Final Research Achievements

Starve treatment after hatching makes XX female medaka functional male. We revealed that the starvation causes a decrease of lipogenesis via a reduced activity of a CoA-producing pathway. The reduction of lipogenesis then leads to repression of dmrt1 expression that is a critical gene for testis development. This result is the first mechanistic demonstration that genetically determined vertebrate is affected by the change of metabolism induced by environment.
We also found genetic regulation on the spectrum of germ cell sex. After expression of germ cell sexual switch gene, foxl3, in germline stem cells, germ cells initiate oogenesis. However, germ cells remains feasible in sexual state and could develop into spermatogenesis. We found that feminization of germ cells establishes by pachytene stage. The mechanism underlying this spectrum demonstrates flexible sex that organisms originally possess and may ensure the base for creation of naturally sex reversed organism during evolution.

Free Research Field

生殖生物

Academic Significance and Societal Importance of the Research Achievements

遺伝的に性が決まる動物であっても、環境によって性が影響されることは知られていたが、その分子機構の一端が明らかになった学術的意義は大きい。同時にこの結果は代謝も性に影響することを示している。また卵巣中で卵が作られる過程においても性には揺らぎ（卵になるか、精子になるか）があり、その揺らぎを引き起こす機構が分子遺伝学的に明らかとなった。このような性スペクトラムの仕組みは、生き物が本来性をフレキシブルに制御できることを示しており、それが自然性転換行う動物や環境性性決定を行う動物の進化を担保してきたと考えられる。また近年議論のあるLGBTの生物学的基盤となっている可能性をも提示している。