Unravelling a complex nature of eukaryotic microbes using ultrastructural analyses and sub-single cell genomics

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01202
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Nomaki Hidetaka 国立研究開発法人海洋研究開発機構, 超先鋭研究開発部門(超先鋭研究開発プログラム), 上席研究員 (90435834)
• Co-Investigator(Kenkyū-buntansha): HUSNIK Filip 沖縄科学技術大学院大学, 進化・細胞・共生の生物学ユニット, 准教授 (30886130)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 単細胞真核生物 / 機能分化

Outline of Final Research Achievements

Benthic foraminifera are unicellular eukaryote but have large cell up to more than 10 cm. They have wide variety of metabolisms and symbiotic relationships and adapted diverse marine environments. We hypothesized that this metabolic diversity may have archived by a "pseudo- multicellular " manner, with each chamber containing cells having a different function. We conducted ultrastructural analysis, intracellular elemental mapping, and gene expression analysis at sub-single cell levels. The distribution of organelles varies greatly depending on the part of the cell, with some areas specialized for energy storage, symbiosis with prokaryotes, and for food digestion. Elemental distribution also confirmed these observations and presumable functions. Genes expression patterns also differ among the positions of chambers, indicating that this giant unicellular organism can have diverse metabolic functions through intracellular functional differentiation.

Free Research Field

深海生態学

Academic Significance and Societal Importance of the Research Achievements

生物の進化は、「単純な単細胞生物が誕生し、それらが共生して真核生物になり、やがて多細胞になり、大型化、複雑化し、現在の動物や植物になった」というストーリーがよく知られている。本研究の成果から、有孔虫などの生物は「単細胞生物が多細胞化することなく独自の異なるメカニズムにより機能分化、大型化したことで、海洋の様々な環境で繁栄している」ことが明らかになり、生物の進化、適応がこれまで以上に複雑かつ謎に満ちたストーリーであることを示している。