著者

黒川 宏之

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.51, no.3, pp.5, 2023 (Released:2023-12-23)

参考文献数

78

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Remote sensing observations and returned sample analysis in Hayabusa2 mission revealed the origin and evolution of the asteroid 162173 Ryugu and its parent body and provided insights into the early solar system history. Here first we review findings of the Hayabusa2 mission, mostly focusing on Ryugu’s physical, chemical, and mineralogical properties. Spectral properties, elemental composition, and mineralogy of the asteroid Ryugu informed from remote-sensing observations of the asteroid and analysis of its returned samples show that Ryugu closely resembles CI chondrite meteorites, while its properties more primitive than CI chondrite meteorites are also identified. The presence of CO2 fluid inclusions and nucleosynthetic isotopic characteristics point to a distant formation location distinct from those of other carbonaceous chondrite parent bodies for Ryugu’s and CI chondrite parent bodies, possibly beyond Jupiter’s formation location. The homogeneity of Ryugu’s surface suggests that the parent body may be an undifferentiated body. Next, we place those findings in broader context with the solar system explorations, astronomical observations, and theoretical studies to highlight unsolved issues on the origin and evolution of the asteroid Ryugu and the early solar system. While Ryugu’s origin beyond Jupiter’s orbit has been widely discussed in previous studies, combined evidence including Jupiter’s envelope composition, asteroid taxonomy, and theoretical studies do not rule out other possibilities. Observational evidence and theoretical studies suggest water-rock differentiation of large asteroids (parent bodies) and its role in chemical evolution. We conclude with discussion on future studies to better understand the origin of the asteroid Ryugu and the evolution of the early solar system.

著者

水内 良

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.49, no.3, pp.10, 2021 (Released:2021-12-18)

参考文献数

34

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Origins-of-life hypotheses generally posit evolution from simple molecular replicators, such as RNA, to complex living systems. The understanding of how molecular replicators could have evolved on the early Earth has been advanced through theoretical research. However, experimental verification was generally hindered due to the lack of appropriate experimental systems (i.e., molecular replicators that can undergo Darwinian evolution). Here, I describe our recent approach to develop and evolve such a model replication system to illuminate possible evolutionary pathways that would have led to the emergence of complex life.

著者

栗栖 実 今井 正幸

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.51, no.2, pp.3, 2023 (Released:2023-06-23)

参考文献数

333

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Vesicles are membrane compartments in aqueous solutions consisting of self-assembled amphiphilic molecules such as lipids. Before the first living systems emerged from non-living forms of matter, functional macromolecules and vesicles must have assembled to form prebiotic self-reproducing compartment systems called “protocells.” Although we cannot observe protocells today, recent advances in soft matter physics, systems chemistry, and synthetic biology are making steady progress in our bottom-up understanding of what bridges non-living and living systems. In this review, we focus on the vesicular compartment aspect of recent protocell research and provide a membrane physics background that helps us understand how protocells reproduced themselves four billion years ago. In addition to prebiotically plausible reactions and dynamics, we also focus on the non-natural (or artificial) approaches that can achieve the same essential concepts of protocells in different ways from biological systems. Therefore, this review will provide knowledge on vesicles also for researchers and students interested in artificial cells and minimal cells.

著者

杉山 博紀

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.51, no.1, pp.1, 2023 (Released:2023-06-23)

参考文献数

46

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Synthesizing a possible earliest cell-like molecular assembly from scratch can contribute to investigating the underlying design principle of the current living organisms. Liposomes, closed phospholipid bilayers, are a promising scaffold for this synthetic approach. Therein, the low permeability of the phospholipid membrane prohibits the efficient supply of molecules encapsulated inside, which makes it challenging to assume liposome-based protocells at the origin of life. Using the developed automatic observation platform based on microfluidic devices (termed MANSIONs), we find that liposomes can accumulate some molecules, including analogs of adenosine triphosphate and polyethylene glycol, against their concentration gradient, without proteins but under a hydrodynamic condition. We further elucidate that the negatively charged phospholipids in the liposomal membrane are crucial for this unique molecular transport across the phospholipid membrane (hydrodynamic accumulation; HDA). Finally, we discuss the potential contribution of HDA in investigating the origin of life.

著者

池原 健二

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.40, no.4, pp.62-68, 2012 (Released:2021-12-29)

参考文献数

19

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生命の起原を解明するために必要なことは、生命が生きる上で最も重要な遺伝子や遺伝情報を翻訳する際に使用される遺伝暗号、そして、タンパク質の三つの要素がどのようにして形成されたのかを説明することであろう。これまでも、宇宙起原説や熱水噴出孔起原説、がらくたワールド仮説、そして、RNAワールド仮説などが生命の起原を説明する考えとして提出されてきた。しかし、そのいずれもが、遺伝子や遺伝暗号、そして、タンパク質がどのようにして形成されてきたのかを説明していない。いや、説明できない考えとなっている。それに対して、私が提唱している[GADV]-タンパク質ワールド仮説(略して、GADV仮説)は、遺伝子、遺伝暗号、そして、タンパク質の形成過程を示しながら、自己矛盾なく生命の起原を説明できる可能性の大きな考えとなっている。本総説では、GADV仮説の要点と長所、遺伝子や遺伝暗号、そして、タンパク質の形成過程、および、GADV仮説をより確かなものとするにはどのような実験的証拠が必要なのかなどについて解説する。

著者

古賀 俊貴

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.51, no.4, pp.6, 2023 (Released:2023-12-23)

参考文献数

35

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The study of extraterrestrial organic molecules has entered a new era, facilitated by the capability to retrieve primordial materials from carbonaceous asteroids and perform comprehensive laboratory analyses on Earth. On December 6, 2020, the asteroid explorer "Hayabusa2" successfully completed its mission, returning 5.4 g of samples from the near-Earth asteroid "Ryugu (162173)". For astroorganic chemists, the initial analysis of Ryugu samples provided a golden opportunity to conduct comprehensive organic chemical analyses on the soluble organic matter (SOM) in the more chemically pristine sample compared to other Solar System materials previously analyzed in laboratories. This review outlines the distribution and characteristics of the organic molecules identified in the Ryugu samples, including amino acids and nucleobases. The diversity of Ryugu's SOM is not only comparable to that of previously analyzed carbonaceous chondrites, but is also characterized by sulfur-rich compounds such as polythionic acids. The discovery of more than ten types of amino acids and the nucleobase 'uracil' in the Ryugu samples marks a significant milestone in both astrochemistry and astrobiology. The molecular distribution of amino acids, amines, and carboxylic acids suggests these molecules were influenced by low-temperature hydrothermal reactions on the Ryugu’s parent body. The prominent distribution of tetracyclic PAHs suggests that it might not only be influenced by hydrothermal reactions but also indicates the possibility that interstellar origins have been partially preserved. The initial SOM analysis showed that despite the harsh conditions of solar heat, ultraviolet light, cosmic ray irradiation, and high vacuum, Ryugu’s surface and subsurface materials have retained a wide variety of organic molecules. Therefore, SOM on C-type asteroids, like Ryugu, could have been supplied to early Earth and other celestial bodies through releases caused by interstellar collisions.

著者

四方 勝

出版者

生命の起原および進化学会

雑誌

Viva origino (ISSN:09104003)

巻号頁・発行日

vol.32, no.1, 2004-02-28

著者

河合 純 癸生川 陽子 小林 憲正

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.46, no.1, pp.1, 2018 (Released:2021-11-16)

参考文献数

74

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How to find life on extraterrestrial bodies? Firstly, we need to define what life is. Although there are a large number of definitions proposed by individual scientists, there are no definition that everyone agrees. If we would describe the characteristics that all the terrestrial organisms have, they would include the followings: 1) metabolisms, 2) reproductions, 3) boundaries and 4) Darwinian evolutions. The Earth-type life consist of DNA using 4 nucleic acid bases, proteins composed of basically 20 kinds of amino acids, and cell membrane mainly composed of phospholipids. However, it is not well known that how Earth-type life select these organic compounds. In this paper, first we will explain the organic compounds used by terrestrial organisms. We will then introduce the analytical methods of organic compounds used in the past planetary explorations, as well as in the ground laboratories. Finally we would like to introduce future astrobiology missions considered in Japan, together with analytical techniques that could be used in them.

著者

田村 浩二 長谷川 典巳

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.41, no.4, pp.29-33, 2013 (Released:2021-12-29)

参考文献数

29

著者

古賀 俊貴

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.50, no.3, pp.5, 2022 (Released:2022-12-27)

参考文献数

90

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Since the detection of extraterrestrial amino acids in the Murchison meteorite, dramatic improvements in chromatographic techniques with mass spectrometry over the past half century have revealed the presence of a wide variety of organic compounds of extraterrestrial origin in carbonaceous meteorites. The possibility that biologically relevant compounds (amino acids, sugars, nucleobases, etc.) contained in extraterrestrial materials were transported to the early Earth and contributed to the primordial molecular evolution has been discussed in many previous works. In this sense, organic analysis of carbonaceous meteorites provides unique geological evidence for understanding the distributions of organic molecules that may have been available on the prebiotic Earth. Equally important, determining how the abiotic molecules in meteorites were formed in the Solar system will provide important clues for considering the pristine chemical reactions that proceeded on the early Earth. Here, this review overviews comprehensive reports on the distributions and characteristics of amino acids, sugars, and nucleobases found in carbonaceous meteorites with the aim of sharing the knowledge on pre-biologically relevant molecules of extraterrestrial origin.

著者

浦田 秀仁

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.40, no.Supplement, pp.1-50, 2012 (Released:2021-12-29)

著者

櫻沢 繁

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.38, no.Supplement, pp.1-35, 2010 (Released:2022-01-18)

著者

島田 秋彦

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.30, no.1, pp.1-53, 2002 (Released:2022-02-23)

著者

河原林 裕

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.41, no.Supplement, pp.1-50, 2013 (Released:2021-12-29)

著者

山岸 明彦 矢野 創 小林 憲正 横堀 伸一 橋本 博文 山下 雅道 田端 誠 河合 秀幸

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.36, no.4, pp.72-76, 2008 (Released:2022-01-18)

参考文献数

23

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たんぽぽ(蒲公英,dandelion)は綿毛のついた種子を風に乗せて頒布し,その生息域を広げる多年草である.我々は,この名前のもと,国際宇宙ステーション-JEM(日本実験棟)上での微生物と生命材料となり得る有機化合物の天体間の移動の可能性の検討と微小隕石の検出および解析実験を提案する.我々は,超低密度エアロゲルを用いることで,微小隕石やその他の微粒子を捕集することが可能であると考えている.低軌道上で超低密度エアロゲルを一定期間曝露することで宇宙空間で微粒子を捕集する.エアロゲル表面と衝突トラックの顕微観察の後,エアロゲルの様々な解析を行う.衝突トラックの詳細な検討により,国際宇宙ステーション周辺のデブリのサイズと速度が明らかにできると期待される.エアロゲル中に残存した粒子に関して,鉱物学的,有機化学的,及び微生物学的な検討を行う.一方,宇宙環境下での微生物の生存可能性について検討するため,微生物を直接宇宙空間に曝露する実験も行う.同様に,宇宙環境下での有機化合物の変性の可能性を検討するため,有機化合物の宇宙空間への直接曝露実験も行う.これらの実験を行うための装置はすべて受動的な装置であり,そのための装置の基本構造,装置回収後の解析法も,既に確立されている.

著者

長谷川 典巳

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.34, no.1, pp.1-39, 2006 (Released:2022-01-29)

著者

薮田 ひかる

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.36, no.2, pp.20-43, 2008 (Released:2022-01-18)

参考文献数

128

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This review (in Japanese) highlights the results on the Stardust mission organics preliminary examination of the returned Comet 81P/Wild 2 particles, based on the Science article published in December 15, 2006. The recent developments of studies on organics in chondritic meteorites and/or interstellar dust particles using modern instruments are also described for seeking relations of organic characteristics among the three extraterrestrial samples. In addition, potential chemistry for which cometary and meteoritic organics were responsible as a source of exogenous delivery to the early Earth is discussed.

著者

三田 肇

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.39, no.Supplement, pp.1-34, 2011 (Released:2021-12-29)

被引用文献数

1

著者

小林 憲正

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.36, no.4, pp.77-82, 2008 (Released:2022-01-18)

参考文献数

34

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A great number of experiments have been done to examine possible prebiotic formation of bioorganic compounds such as amino acids in possible primitive environments. There are two scenario of prebiotic formation of bioorganic compounds: An endogenous formation scenario and an exogenous formation scenario. The latter scenario was supported by the facts that a wide variety of organic compounds were detected in meteorites and comets. It is now suggested that organic compounds in extraterrestrial bodies were originally formed in extremely cold environments such as in molecular clouds. Laboratory experiments showed that complex precursors of amino acids could be formed from simulated interstellar media by irradiation with high-energy particles. It was suggested that such extraterrestrial organic compounds were delivered mainly by cosmic dusts. We have, however, very limited information on organic compounds in cosmic dusts since they are captured within terrestrial environments. We proposed a novel astrobiology mission “Tanpopo” by utilizing the international space station. In the mission, cosmic dusts will be collected with ultra-low-density aerogel, and organic compounds in them will be analyzed. In the mission, organic compounds simulating extraterrestrial organics will be directly exposed to solar ultraviolet light and cosmic rays at the same time to study the fate of organic compounds in cosmic dusts near the Earth orbit.

著者

山岸 明彦

出版者

生命の起原および進化学会

雑誌

Viva Origino (ISSN:09104003)

巻号頁・発行日

vol.49, no.2, pp.6, 2021 (Released:2021-11-25)

参考文献数

87

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In my college age, I read the Japanese translation of “The Origin of Life” written by Oparin, though understood a little. During graduate school and postdoctoral position in Japan and USA, I started the research experience in the field of photosynthesis. After returning back to Japan, I started the research career in Tokyo Institute of Technology, where I started the research on the structure of genomic DNA of archaebacteria. We analyzed the characteristics of the last universal common ancestor, which we named Commonote commonote, and found that the species was hyper-thermophilic, based on the experimental results obtained by reproducing an enzyme possessed by C. commonote, in Tokyo University of Pharmacy and Life Sciences. Then, we started the research on microbiota in deep see hydrothermal system as well as high atmosphere. Later, we started the space experiment Tanpopo on the International Space Station. The research field is now called Astrobiology.   There are ample of research results related to the RNA-origin of life. The ribonucleotides were produced nonbiologically in aqueous media by a reaction process with drying steps. The ribonucleotides were polymerized without biological catalyst. RNA-replicating ribozyme with the length of 200 nucleotides capable of replicating 200-nucleotide-long template has been reported. The process from the protocell containing self-replicating ribozyme surrounded by lipid membrane to the last universal common ancestor Commonote commonote is proposed.