Explore the potential of epigenetic regulation in the chemosymbiotic system

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07227
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: System genome science
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: TAKAKI Yoshihiro 国立研究開発法人海洋研究開発機構, 深海・地殻内生物圏研究分野, 主任技術研究員 (10399561)
• Co-Investigator(Kenkyū-buntansha): 生田 哲朗 国立研究開発法人海洋研究開発機構, 海洋生物多様性研究分野, 技術研究員 (80584846)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 化学合成 / 共生 / エピジェネティクス

Outline of Final Research Achievements

Chemosymbiotic animals harboring methane-oxidizing bacteria are largely dependent on chemically-derived energy and nutrients provided by symbionts. It still remain unresolved as to how the symbiont growth is controlled to keep the within-host population size of symbionts to be constant. We focus on whether epigenetic regulation is associated with sustaining the symbiont population in host. PacBio whole genome sequencing was conducted for two symbionts of deep-sea Bathymodiolus mussels, and one free-living bacteria. The sequence analysis showed that these methane-oxidizing bacteria have the genome ranging 4 Mb to 4.5 Mb, of which about 50 thousands of sites is methylated. From the transcriptome analysis, expression of some genes in both symbionts are over 10-fold higher than those of free-living one. Some methylation sites were found in the upstream region of their gene. These finding indicates that symbiosis have the potential for enabling the epigenetic regulation.

Free Research Field

ゲノム微生物学

Academic Significance and Societal Importance of the Research Achievements

化学合成生態系における共生システムについて、宿主動物が、「どのように共生細菌を維持しているか？」といった、未だ未解明な問いに対して、本研究によって、エピジェネティクス的な遺伝子制御の可能性を示すことができた。この新たな視点での研究は、ゲノミックスの成果と合わせ、共生機構の維持、継承メカニズムの解明に繋がるはずである。また、そのメカニズムの解明は、共生系を利用した物質生産を目指す共生工学に大きく寄与すると考えられる。