D.Sc. in Chemistry, University of Tokyo in 1982. Professor, Yokohama National University until 2020, and now Professor Emeritus. My research fields are analytical chemistry and astrobiology, especially prebiotic chemistry.
Origins of Life and Evolution of Biospheres - ORIGINS LIFE EVOL BIOSPHERE, 1994
It has been controversy that bioorganic compounds were formed on primitive earth or formed in spa... more It has been controversy that bioorganic compounds were formed on primitive earth or formed in space and supplied to the earth before the origin of life on the earth. The authors experimentally verified the possibility of the formation of bioorganic compounds under both primitive terrestrial and extraterrestrial conditions.
Microbiological activities can be detected in various extreme environments on Earth, which sugges... more Microbiological activities can be detected in various extreme environments on Earth, which suggest that extraterrestrial environments, such as on Mars, could host life. There have been proposed a number of biomarkers to detect extant life mostly based on specific molecules. Because terrestrial organisms have catalytic proteins (enzymes), enzymatic activity may also be a good indicator to evaluate biological activities in extreme environments. Phosphatases are essential for all terrestrial organisms because phosphate esters are ubiquitously used in genetic molecules (DNA/RNA) and membranes. In this study, we evaluated microbial activity in soils of the Atacama Desert, Chile, by analysing several biomarkers, including phosphatase activity. Phosphatases extracted with Tris buffer were assayed fluorometrically using 4-methylumbelliferyl phosphate as a substrate. The horizontal distribution of phosphatase activity and other parameters in soils from the Atacama Desert showed that phosphat...
Exobiology: Matter, Energy, and Information in the Origin and Evolution of Life in the Universe, 1998
For the generation of life, bioorganic compounds are essential. It has been supposed that most of... more For the generation of life, bioorganic compounds are essential. It has been supposed that most of bioorganic compounds essential to the first life were formed in the planets. Various kinds of simulation experiments have been performed to examine how these compounds were abiotically synthesized in primitive planetary environments. In these days, however, the primitive earth atmosphere is thought to be “mildly-reduced,” containing carbon monoxide, carbon dioxide, nitrogen and water (Kasting, 1990). If the primitive atmosphere was “mildly-reduced” type, formation of amino acids and other bioorganic compounds essential for origin of life were quite difficult (Schlesinger and Miller, 1983; Chang and Bur-Nun, 1983).
A great number of prebiotic synthesis experiments under possible primitive conditions have been c... more A great number of prebiotic synthesis experiments under possible primitive conditions have been conducted since the 1950s. In most of the prebiotic synthesis experiments of the earlier era, strongly reducing gas mixtures were used as a primitive Earth atmosphere, and amino acids and other bioorganic compounds were successfully synthesized. Their formation mechanisms were explained by step-by-step modes, such as the Strecker synthesis. However, such a strongly reducing atmosphere is questioned and the contributions of extraterrestrial organics are under consideration. We learned that quite complex organic compounds could be formed under interstellar environments through the analysis of extraterrestrial samples and products of experiments simulating extraterrestrial conditions. Simulation experiments are also introduced to examine the possible origins of the homochirality of biomolecules. Experiments simulating submarine hydrothermal systems were also conducted. It is very difficult to verify the origin of life on the Earth, since relics of the prebiotic synthesis do not remain on the Earth. It would be possible, however, to examine possible origins of life in space through the synergy of planetary exploration and space experiments.
Contents 1. Introduction 1.1. A workshop and this document 1.2. Framing origins of life science 1... more Contents 1. Introduction 1.1. A workshop and this document 1.2. Framing origins of life science 1.2.1. What do we mean by the origins of life (OoL)? 1.2.2. Defining life 1.2.3. How should we characterize approaches to OoL science? 1.2.4. One path to life or many? 2. A Strategy for Origins of Life Research 2.1. Outcomes-key questions and investigations 2.1.1. Domain 1: Theory 2.1.2. Domain 2: Practice 2.1.3. Domain 3: Process 2.1.4. Domain 4: Future studies 2.2. EON Roadmap 2.3. Relationship to NASA Astrobiology Roadmap and Strategy documents and the European AstRoMap Appendix I Appendix II Supplementary Materials References.
The extraterrestrial delivery of organics to primitive Earth has been supported by many laborator... more The extraterrestrial delivery of organics to primitive Earth has been supported by many laboratory and space experiments. Minerals played an important role in the evolution of meteoritic organic matter. In this study, we simulated aqueous alteration in small bodies by using a solution mixture of H2CO and NH3 in the presence of water at 150 °C under different heating durations, which produced amino acids after acid hydrolysis. Moreover, minerals were added to the previous mixture to examine their catalyzing/inhibiting impact on amino acid formation. Without minerals, glycine was the dominant amino acid obtained at 1 d of the heating experiment, while alanine and β-alanine increased significantly and became dominant after 3 to 7 d. Minerals enhanced the yield of amino acids at short heating duration (1 d); however, they induced their decomposition at longer heating duration (7 d). Additionally, montmorillonite enhanced amino acid production at 1 d, while olivine and serpentine enhance...
Origins of Life and Evolution of Biospheres - ORIGINS LIFE EVOL BIOSPHERE, 1994
It has been controversy that bioorganic compounds were formed on primitive earth or formed in spa... more It has been controversy that bioorganic compounds were formed on primitive earth or formed in space and supplied to the earth before the origin of life on the earth. The authors experimentally verified the possibility of the formation of bioorganic compounds under both primitive terrestrial and extraterrestrial conditions.
Microbiological activities can be detected in various extreme environments on Earth, which sugges... more Microbiological activities can be detected in various extreme environments on Earth, which suggest that extraterrestrial environments, such as on Mars, could host life. There have been proposed a number of biomarkers to detect extant life mostly based on specific molecules. Because terrestrial organisms have catalytic proteins (enzymes), enzymatic activity may also be a good indicator to evaluate biological activities in extreme environments. Phosphatases are essential for all terrestrial organisms because phosphate esters are ubiquitously used in genetic molecules (DNA/RNA) and membranes. In this study, we evaluated microbial activity in soils of the Atacama Desert, Chile, by analysing several biomarkers, including phosphatase activity. Phosphatases extracted with Tris buffer were assayed fluorometrically using 4-methylumbelliferyl phosphate as a substrate. The horizontal distribution of phosphatase activity and other parameters in soils from the Atacama Desert showed that phosphat...
Exobiology: Matter, Energy, and Information in the Origin and Evolution of Life in the Universe, 1998
For the generation of life, bioorganic compounds are essential. It has been supposed that most of... more For the generation of life, bioorganic compounds are essential. It has been supposed that most of bioorganic compounds essential to the first life were formed in the planets. Various kinds of simulation experiments have been performed to examine how these compounds were abiotically synthesized in primitive planetary environments. In these days, however, the primitive earth atmosphere is thought to be “mildly-reduced,” containing carbon monoxide, carbon dioxide, nitrogen and water (Kasting, 1990). If the primitive atmosphere was “mildly-reduced” type, formation of amino acids and other bioorganic compounds essential for origin of life were quite difficult (Schlesinger and Miller, 1983; Chang and Bur-Nun, 1983).
A great number of prebiotic synthesis experiments under possible primitive conditions have been c... more A great number of prebiotic synthesis experiments under possible primitive conditions have been conducted since the 1950s. In most of the prebiotic synthesis experiments of the earlier era, strongly reducing gas mixtures were used as a primitive Earth atmosphere, and amino acids and other bioorganic compounds were successfully synthesized. Their formation mechanisms were explained by step-by-step modes, such as the Strecker synthesis. However, such a strongly reducing atmosphere is questioned and the contributions of extraterrestrial organics are under consideration. We learned that quite complex organic compounds could be formed under interstellar environments through the analysis of extraterrestrial samples and products of experiments simulating extraterrestrial conditions. Simulation experiments are also introduced to examine the possible origins of the homochirality of biomolecules. Experiments simulating submarine hydrothermal systems were also conducted. It is very difficult to verify the origin of life on the Earth, since relics of the prebiotic synthesis do not remain on the Earth. It would be possible, however, to examine possible origins of life in space through the synergy of planetary exploration and space experiments.
Contents 1. Introduction 1.1. A workshop and this document 1.2. Framing origins of life science 1... more Contents 1. Introduction 1.1. A workshop and this document 1.2. Framing origins of life science 1.2.1. What do we mean by the origins of life (OoL)? 1.2.2. Defining life 1.2.3. How should we characterize approaches to OoL science? 1.2.4. One path to life or many? 2. A Strategy for Origins of Life Research 2.1. Outcomes-key questions and investigations 2.1.1. Domain 1: Theory 2.1.2. Domain 2: Practice 2.1.3. Domain 3: Process 2.1.4. Domain 4: Future studies 2.2. EON Roadmap 2.3. Relationship to NASA Astrobiology Roadmap and Strategy documents and the European AstRoMap Appendix I Appendix II Supplementary Materials References.
The extraterrestrial delivery of organics to primitive Earth has been supported by many laborator... more The extraterrestrial delivery of organics to primitive Earth has been supported by many laboratory and space experiments. Minerals played an important role in the evolution of meteoritic organic matter. In this study, we simulated aqueous alteration in small bodies by using a solution mixture of H2CO and NH3 in the presence of water at 150 °C under different heating durations, which produced amino acids after acid hydrolysis. Moreover, minerals were added to the previous mixture to examine their catalyzing/inhibiting impact on amino acid formation. Without minerals, glycine was the dominant amino acid obtained at 1 d of the heating experiment, while alanine and β-alanine increased significantly and became dominant after 3 to 7 d. Minerals enhanced the yield of amino acids at short heating duration (1 d); however, they induced their decomposition at longer heating duration (7 d). Additionally, montmorillonite enhanced amino acid production at 1 d, while olivine and serpentine enhance...
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