Transition mechanism between XY and ZW sex determination system in medaka fishes

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18590
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Genetics/Chromosome dynamics
• Research Institution: Nagahama Institute of Bio-Science and Technology (2017-2018); National Institute for Basic Biology (2016)
• Principal Investigator: Takehana Yusuke 長浜バイオ大学, バイオサイエンス学部, 准教授 (60432093)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 性決定遺伝子 / 性染色体 / 遺伝子重複

Outline of Final Research Achievements

Sex chromosomes harbor a primary sex-determining signal that triggers sexual development of the organism. However, independent evolution of sex chromosomes is widespread in non-mammalian vertebrates, suggesting that sex determination mechanisms are regulated by different genes and have evolved rapidly. To understand the molecular mechanism underling the XY-ZW transitions, we analyzed sex chromosomes and sex-determining genes of medaka species. We found that duplicated copies of Dmrt1 at the Y chromosomes were required for male determination in the XY species, Oryzias haugiangensis. Although no sex-determining gene has been isolated in the ZW species, O. hubbsi or O. javanicus, Gsdf is not a conserved downstream component of male determination pathway in O. hubbsi. These results suggest that sex-determining genes have more diverse downstream targets between XY and ZW systems than previously thought.

Free Research Field

遺伝学

Academic Significance and Societal Importance of the Research Achievements

ほとんどすべての動物にオス・メスがあるのと対照的に、オス・メスを決定する仕組みは動物種によってさまざまである。しかし、この性決定の仕組みがどのように多様化してきたのかはほとんどわかっていない。今回の研究により、メダカ属という近縁なグループ内で、下流遺伝子の重複転座によって異なる性染色体が独立に進化してきたことや、XY型とZW型で性決定遺伝子の作用点が異なることが明らかになってきた。これらの成果は、性決定の仕組みが（従来考えられてきたよりも）さらに多様である可能性を示唆している。