Intercellular recognition between sperm and eggs: Studies on the allogeneic and xenogeneic molecular recognition

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H03672
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Cell biology
• Research Institution: Kinjo Gakuin University (2019-2020); Nagoya University (2017-2018)
• Principal Investigator: Sawada Hitoshi 金城学院大学, 生活環境学部, 教授 (60158946)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 受精 / 自家不和合性 / 細胞間相互作用 / ホヤ / 精子 / 卵

Outline of Final Research Achievements

Ascidians are hermaphrodites, which release sperm and eggs nearly simultaneously, but self-fertilization is prohibited in Ciona intestinalis and Halocynthia roretzi. In C. intestinalis, we reported that two gene pairs, s-Themis-A and v-Themis-A in locus A, and s-Themis-B and v-Themis-B in locus B, play a pivotal role in self-sterility. Here, we identified one addition gene pair s/v-Themis-B2 in locus B involved in this system. Therefore, three multi-allelic gene pairs, s/v-Themis-A, -B, and B2, are responsible for self-sterility in C. intestinalis. We previously showed that the increase in intracellular Ca2+ takes place after sperm recognizes the vitelline coat of the egg as self-egg, resulting in the detachment from the vitelline coat. Here, we revealed low Ca2+ seawater enables self-fertilization, probably because of inhibition of Ca2+. However, these phenomena were never observed in H. roretzi, suggesting that the mechanism of self-sterility appears to be different.

Free Research Field

細胞生物学

Academic Significance and Societal Importance of the Research Achievements

ホヤの自家不稔性機構は動植物共通の生殖原理に基づくと考えられる。また、カタユウレイボヤで発見された精子s-Themisは、哺乳類精子のPKDREJと相同な分子で、多型がみられる。従って、配偶子間相互作用において同系統個体と認識されて受精が阻害され不妊になる可能性も考えられる。ホヤの受精研究から、ヒトの不妊診断・治療の研究に発展する可能性も考えられ、社会的にも臨床医学的にも意義深い研究である。