2021 Fiscal Year Final Research Report

Experimental Validation of "the Garakuta World" Hypothesis for Origins of Life

Research Project

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Project/Area Number	19K21895
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 17:Earth and planetary science and related fields
Research Institution	Yokohama National University
Principal Investigator	Kobayashi Kensei 横浜国立大学, 大学院工学研究院, 名誉教授 (20183808)
Co-Investigator(Kenkyū-buntansha)	三田肇福岡工業大学, 工学部, 教授 (00282301) 癸生川陽子横浜国立大学, 大学院工学研究院, 准教授 (70725374)
Project Period (FY)	2019-06-28 – 2022-03-31
Keywords	生命の起源 / がらくたワールド / アミノ酸前駆体 / 触媒機能 / 宇宙線 / 宇宙実験 / 地球外生命探査
Outline of Final Research Achievements	It was conventionally supposed that chemical evolution toward the origin of life proceeded step by step. We found that complex molecules whose molecular weights were thousands were formed when a mixture of simple molecules such as CO and NH3 was irradiated with high energy particles. We named them garakuta molecules. Garakuta molecules contained amino acid precursors and molecules with catalytic activity. Stability of amino acid precursors in garakuta molecules were compared with free amino acids and simple amino acid precursors such as hydantoins by laboratory simulations and space experiments: Garakuta molecules were robust as amino acid precursors. It is difficult to find relics of prebiotic chemical evolution on the Earth. Thus it is necessary to make efforts to find it in extraterrestrial environments. We proposed to use catalytic activities for detection of extraterrestrial life or Garakuta World on other celestial bodies.
Free Research Field	アストロバイオロジー
Academic Significance and Societal Importance of the Research Achievements	生命の起源研究は，オパーリンらによる化学進化仮説が有力で，1950年代以降は実験による検証も多数行われてきた。それらの前提として，まずは小分子が生成し，それらが徐々に繋がって大きい分子になったとする段階的生成説が主流であった。本研究において，高エネルギー粒子線が小分子に作用した場合に，分子量数千の有機分子が生成し，その中にアミノ酸前駆体や触媒機能を有する分子が含まれていることが証明された。このような高分子態有機物（がらくた分子）を経由する生命起源説はこれまでなく，生命起源研究にあらたな方向を示すものといえる。