Revealing the mechanism behind pronuclear selection in Tetrahymena thermophila

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20643
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0701:Biology at molecular to cellular levels, and related fields
• Research Institution: Nihon University
• Principal Investigator: AKEMATSU Takahiko 日本大学, 文理学部, 助教 (90906637)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: テトラヒメナ / 繊毛虫類 / 配偶子 / 核 / 核膜 / 運命決定

Outline of Final Research Achievements

Unlike other eukaryotes, the ciliated protist Tetrahymena has both germline and soma in a single cell as two spatially separate nuclei, germline (micro-) and somatic (macro-) nuclei, and the lifecycle is performed between the two types of nuclei without fusion or disintegration of the individual cells. During sexual reproduction in Tetrahymena, cells of complementary mating type pair undergo simultaneous meiosis and fertilize each other. In both mating partners only one of the four meiotic products is selected to gives rise to gametic pronuclei. In this study, we screened genes that show a high expression level in the pre-zygotic period of mating and found two genes (Dear3, Mfs1) as essential factors for selective gametogenesis and the subsequent reciprocal fertilization. This finding provides a new insight into understanding the core and diversified parts of eukaryotic sexual reproduction.

Free Research Field

細胞生物学

Academic Significance and Societal Importance of the Research Achievements

繊毛虫類の有性生殖は、動物の精子と卵に見られるような細胞の融合を伴うことなく、異性細胞間での核の交換により行われる点で極めてユニークである。この仕組みの解明は、より広い真核生物における有性生殖の多彩性を理解するための重要な研究課題である。本研究で得られた成果は、核を単位とした配偶子形成に必須な新規遺伝子を明らかにしたものである。配偶子形成に必要な遺伝子には、繊毛虫類に特異的なものと、多くの生物に広く保存されているものが含まれる。今後の研究の進展により、真核生物がもつ配偶子形成メカニズムの共通性と、進化的なバリエーションの理解に繋がると期待される。