The origin of sex chromosome systems

2021 Fiscal Year Final Research Report

• Project Area: Spectrum of the Sex: a continuity of phenotypes between female and male
• Project/Area Number: 17H06425
• 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: The University of Tokyo
• Principal Investigator: Kikuchi Kiyoshi 東京大学, 大学院農学生命科学研究科(農学部), 教授 (20292790)
• Co-Investigator(Kenkyū-buntansha): 小山 喬 長崎大学, 水産・環境科学総合研究科(水産), 准教授 (40749701)
• Project Period (FY): 2017-06-30 – 2022-03-31
• Keywords: 性決定遺伝子 / 性染色体 / 組換え抑制 / 魚類 / 性特異的優性効果

Outline of Final Research Achievements

Sex chromosomes of many species are dimorphic due to suppression of recombination. However, the initial process of recombination suppression has been elusive. In this study, we analyzed the initial process of sex chromosome evolution using a group of fish species that are expected to have chromosomes before and after the dimorphism. We confirmed that Yellowtail fishes have sex chromosomes before and after recombination suppression. Although sex chromosome inversion has been regarded as the main cause of recombination suppression, no inversion was observed in Yellowtail fishes, suggesting the existence of a novel recombination inhibition mechanism. We also identified candidate mutations that caused recombination suppression. In pufferfishes, we found that sex-determining regions containing multiple genes moved around in the genome, and proposed the hypothesis that recombination repression is the cause of this phenomenon.

Free Research Field

水産遺伝学

Academic Significance and Societal Importance of the Research Achievements

多くの生物種の性染色体は、組換え抑制が原因で異形化している。しかし、組換え抑制発達の初期過程は不明であった。本研究は、異形化前後の染色体をもつ魚類近縁種群を対象として、性染色体進化の初期プロセスの一端を明らかとした。ブリ類の研究からは、これまでの説とは異なるメカニズムで組換え抑制が開始される可能性がしめされた。フグ類の研究からは、性決定領域がゲノム中を動き回るという現象が明らかとなった。本研究によりもたらされた知見が生物界に普遍的なものであるかどうかは、今後の研究によって明らかになると思われる。