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Lyons TW, Tino CJ, Fournier GP, Anderson RE, Leavitt WD, Konhauser KO, Stüeken EE. Co-evolution of early Earth environments and microbial life. Nat Rev Microbiol 2024; 22:572-586. [PMID: 38811839 DOI: 10.1038/s41579-024-01044-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2024] [Indexed: 05/31/2024]
Abstract
Two records of Earth history capture the evolution of life and its co-evolving ecosystems with interpretable fidelity: the geobiological and geochemical traces preserved in rocks and the evolutionary histories captured within genomes. The earliest vestiges of life are recognized mostly in isotopic fingerprints of specific microbial metabolisms, whereas fossils and organic biomarkers become important later. Molecular biology provides lineages that can be overlayed on geologic and geochemical records of evolving life. All these data lie within a framework of biospheric evolution that is primarily characterized by the transition from an oxygen-poor to an oxygen-rich world. In this Review, we explore the history of microbial life on Earth and the degree to which it shaped, and was shaped by, fundamental transitions in the chemical properties of the oceans, continents and atmosphere. We examine the diversity and evolution of early metabolic processes, their couplings with biogeochemical cycles and their links to the oxygenation of the early biosphere. We discuss the distinction between the beginnings of metabolisms and their subsequent proliferation and their capacity to shape surface environments on a planetary scale. The evolution of microbial life and its ecological impacts directly mirror the Earth's chemical and physical evolution through cause-and-effect relationships.
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Affiliation(s)
- Timothy W Lyons
- Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA.
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA.
| | - Christopher J Tino
- Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA.
| | - Gregory P Fournier
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rika E Anderson
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA
- Biology Department, Carleton College, Northfield, MN, USA
| | - William D Leavitt
- Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
- Department of Chemistry, Dartmouth College, Hanover, NH, USA
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Eva E Stüeken
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
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2
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Gonçalves D. Rethinking life and predicting its origin. Theory Biosci 2024; 143:205-215. [PMID: 38922566 DOI: 10.1007/s12064-024-00420-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 06/24/2024] [Indexed: 06/27/2024]
Abstract
The definition, origin and recreation of life remain elusive. As others have suggested, only once we put life into reductionist physical terms will we be able to solve those questions. To that end, this work proposes the phenomenon of life to be the product of two dissipative mechanisms. From them, one characterises extant biological life and deduces a testable scenario for its origin. The proposed theory of life allows its replication, reinterprets ecological evolution and creates new constraints on the search for life.
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Affiliation(s)
- Diogo Gonçalves
- Centro de Química Estrutural and Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001, Lisbon, Portugal.
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3
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Rodriguez LE, Weber JM, Barge LM. Evaluating Pigments as a Biosignature: Abiotic/Prebiotic Synthesis of Pigments and Pigment Mimics in Planetary Environments. ASTROBIOLOGY 2024; 24:767-782. [PMID: 38768415 DOI: 10.1089/ast.2023.0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Pigments serve a multitude of functions in biology including light harvesting for photosynthesis, radiation protection, membrane support, and defense. The ubiquity of pigments-especially within extremophiles found in high-radiation, high-salinity, and dry environments-and their detectability via mission-ready techniques have elevated these molecules as promising targets in the search for evidence of life elsewhere. Moreover, the detection of pigments has been proposed as a "smoking gun" for extraterrestrial life as it has been suggested that these molecules cannot be generated abiotically. However, while pigments may hold promise as a biosignature, current understanding of their possible prebiotic origins remains understudied and uncertain. Better understanding of the abiotic synthesis of pigments is critical for evaluating the biogenicity of any pigment detected during missions, including by the Mars Perseverance rover or from returned samples. Compounding this uncertainty is the broad definition of pigment as it includes any compound capable of absorbing visible light and by itself does not specify a particular chemical motif. While not experimentally verified, there are promising prebiotic routes for generating pigments including hemes, chlorophylls, and carotenoids. Herein, we review the biochemistry of pigments, the inherent assumptions made when searching for these molecules in the field, their abiotic synthesis in industry and prebiotic reactions, prebiotically relevant molecules that can mimic their spectral signatures, and implications/recommendations for future work.
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Affiliation(s)
- Laura E Rodriguez
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Jessica M Weber
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Laura M Barge
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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4
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Shen J, Huang T, Zhang H, Lin W. Hydrochemical and isotopic characteristics of water sources for biological activity across a massive evaporite basin on the Tibetan Plateau: Implications for aquatic environments on early Mars. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 935:173442. [PMID: 38788948 DOI: 10.1016/j.scitotenv.2024.173442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/28/2024] [Accepted: 05/20/2024] [Indexed: 05/26/2024]
Abstract
Covered by vast eolian landforms, gravel deposits, and playas, the worldwide typical evaporite deposit land, Qaidam Basin, in northwestern China is analogous to early Mars when the aridification process had lasted for millions of years since the end of a wetter climate. This study aims to investigate the chemical and isotopic characteristics of waters in an evaporite-rich environment, as well as the habitable conditions therein, that have undergone a transformation similar to early Mars. In May 2023, a total of 26 water samples were collected across the representative central axis of a longitudinal aridity gradient in the Qaidam Basin, including categories of meteoric water, freshwater, standing water accumulated after precipitation, salty lacustrine water, and hypersaline brines to inspect compounds made up of carbon, nitrogen, phosphorus, sulfur, halogen, and metallic elements. As evaporation intensified, the salt types transformed from HCO3-Ca·Na to Cl·SO4-Na or ClMg. The dominance of carbonate will gradually be replaced by sulfate and chloride, leaving much more dilute and less detectable contents. The presence of trace ClO4-, ClO3-, ClO2-, and BrO3- was confirmed in a few of the sampled Qaidam waters, indicating the preservation of oxyhalides in waters within an arid region and possibly the presence of relevant microbial enzymes. The isotopes of water, carbonaceous, and nitrogenous compounds provide valuable references for either abiogenic or biogenic signatures. With undetectable amount, phosphorus was found to be the limiting nutrient in evaporative aquatic environments but not necessarily antibiosignatures. Overall, these results suggest that the paleo-lacustrine environments on Mars are more likely to preserve biosignatures if they feature the dominance of carbonate minerals, bioavailable nitrate, phosphorus, and organic carbon, the presence of thermodynamically unstable oxyhalides, and isotope ratios that point to the involvement of biological activity.
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Affiliation(s)
- Jianxun Shen
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Tianming Huang
- Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huiqing Zhang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Lin
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
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5
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Cockell CS. Astrobiology by Gavriil Tikhov. ASTROBIOLOGY 2024; 24:643-668. [PMID: 38917420 DOI: 10.1089/ast.2024.0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Affiliation(s)
- Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
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6
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Jirasek M, Sharma A, Bame JR, Mehr SHM, Bell N, Marshall SM, Mathis C, MacLeod A, Cooper GJT, Swart M, Mollfulleda R, Cronin L. Investigating and Quantifying Molecular Complexity Using Assembly Theory and Spectroscopy. ACS CENTRAL SCIENCE 2024; 10:1054-1064. [PMID: 38799656 PMCID: PMC11117308 DOI: 10.1021/acscentsci.4c00120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/16/2024] [Accepted: 04/09/2024] [Indexed: 05/29/2024]
Abstract
Current approaches to evaluate molecular complexity use algorithmic complexity, rooted in computer science, and thus are not experimentally measurable. Directly evaluating molecular complexity could be used to study directed vs undirected processes in the creation of molecules, with potential applications in drug discovery, the origin of life, and artificial life. Assembly theory has been developed to quantify the complexity of a molecule by finding the shortest path to construct the molecule from building blocks, revealing its molecular assembly index (MA). In this study, we present an approach to rapidly infer the MA of molecules from spectroscopic measurements. We demonstrate that the MA can be experimentally measured by using three independent techniques: nuclear magnetic resonance (NMR), tandem mass spectrometry (MS/MS), and infrared spectroscopy (IR). By identifying and analyzing the number of absorbances in IR spectra, carbon resonances in NMR, or molecular fragments in tandem MS, the MA of an unknown molecule can be reliably estimated. This represents the first experimentally quantifiable approach to determining molecular assembly. This paves the way to use experimental techniques to explore the evolution of complex molecules as well as a unique marker of where an evolutionary process has been operating.
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Affiliation(s)
- Michael Jirasek
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Abhishek Sharma
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Jessica R. Bame
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - S. Hessam M. Mehr
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Nicola Bell
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Stuart M. Marshall
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Cole Mathis
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Alasdair MacLeod
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Geoffrey J. T. Cooper
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
| | - Marcel Swart
- University
of Girona, Campus Montilivi (Ciencies), c/M.A. Capmany 69, 17003 Girona, Spain
- ICREA, Pg. Lluis Companys
23, 08010 Barcelona, Spain
| | - Rosa Mollfulleda
- University
of Girona, Campus Montilivi (Ciencies), c/M.A. Capmany 69, 17003 Girona, Spain
| | - Leroy Cronin
- School
of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ, U.K.
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7
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Puzzarini C, Ye H, Alessandrini S. Isomerism of CH 2 SO : Accurate structural, energetic, and spectroscopic characterization. J Comput Chem 2024; 45:777-786. [PMID: 38116807 DOI: 10.1002/jcc.27283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/24/2023] [Accepted: 11/28/2023] [Indexed: 12/21/2023]
Abstract
A recent work [Ye et al. Mon. Not. R. Astron. Soc. 2023, 525, 1158] on the gas-phase formation of t-HC(O)SH, already detected in the interstellar medium, pointed out that the trans form of HC(S)OH is a potential candidate for astronomical observations. Prompted by these results, theCH 2 SO family of isomers has been investigated from an energetic point of view using a double-hybrid density functional in combination with a partially augmented triple-zeta basis set. This preliminary study showed that the most stable species of the family are the cis and trans forms of HC(O)SH and HC(S)OH. For their structural and spectroscopic characterization, a composite scheme based on coupled cluster (CC) calculations that incorporates up to the quadruple excitations and accounts for the extrapolation to the complete basis set limit and core correlation effects has been employed. This approach opens to the prediction of rotational constants with an accuracy of 0.1%. A hybrid scheme, based on harmonic frequencies computed using the CC singles, doubles and a perturbative treatment of triples method (CCSD(T)) in conjunction with a quadruple-zeta basis set, allowed us to obtain fundamental vibrational frequencies with a mean absolute error of about 1%.
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Affiliation(s)
- Cristina Puzzarini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
| | - Hexu Ye
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
| | - Silvia Alessandrini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
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8
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Malaterre C. Is Life Binary or Gradual? Life (Basel) 2024; 14:564. [PMID: 38792586 PMCID: PMC11121977 DOI: 10.3390/life14050564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 04/15/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024] Open
Abstract
The binary nature of life is deeply ingrained in daily experiences, evident in the stark distinctions between life and death and the living and the inert. While this binary perspective aligns with disciplines like medicine and much of biology, uncertainties emerge in fields such as microbiology, virology, synthetic biology, and systems chemistry, where intermediate entities challenge straightforward classification as living or non-living. This contribution explores the motivations behind both binary and non-binary conceptualizations of life. Despite the perceived necessity to unequivocally define life, especially in the context of origin of life research and astrobiology, mounting evidence indicates a gray area between what is intuitively clearly alive and what is distinctly not alive. This prompts consideration of a gradualist perspective, depicting life as a spectrum with varying degrees of "lifeness". Given the current state of science, the existence or not of a definite threshold remains open. Nevertheless, shifts in epistemic granularity and epistemic perspective influence the framing of the question, and scientific advancements narrow down possible answers: if a threshold exists, it can only be at a finer level than what is intuitively taken as living or non-living. This underscores the need for a more refined distinction between the inanimate and the living.
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Affiliation(s)
- Christophe Malaterre
- Département de Philosophie, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada;
- Centre Interuniversitaire de Recherche sur la Science et la Technologie (CIRST), Montreal, QC H3C 3P8, Canada
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9
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Mráziková K, Knížek A, Saeidfirozeh H, Petera L, Civiš S, Saija F, Cassone G, Rimmer PB, Ferus M. A Novel Abiotic Pathway for Phosphine Synthesis over Acidic Dust in Venus' Atmosphere. ASTROBIOLOGY 2024; 24:407-422. [PMID: 38603526 DOI: 10.1089/ast.2023.0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
Recent ground-based observations of Venus have detected a single spectral feature consistent with phosphine (PH3) in the middle atmosphere, a gas which has been suggested as a biosignature on rocky planets. The presence of PH3 in the oxidized atmosphere of Venus has not yet been explained by any abiotic process. However, state-of-the-art experimental and theoretical research published in previous works demonstrated a photochemical origin of another potential biosignature-the hydride methane-from carbon dioxide over acidic mineral surfaces on Mars. The production of methane includes formation of the HC · O radical. Our density functional theory (DFT) calculations predict an energetically plausible reaction network leading to PH3, involving either HC · O or H· radicals. We suggest that, similarly to the photochemical formation of methane over acidic minerals already discussed for Mars, the origin of PH3 in Venus' atmosphere could be explained by radical chemistry starting with the reaction of ·PO with HC·O, the latter being produced by reduction of CO2 over acidic dust in upper atmospheric layers of Venus by ultraviolet radiation. HPO, H2P·O, and H3P·OH have been identified as key intermediate species in our model pathway for phosphine synthesis.
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Affiliation(s)
- Klaudia Mráziková
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Antonín Knížek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czechia
| | - Homa Saeidfirozeh
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Lukáš Petera
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Prague, Czechia
| | - Svatopluk Civiš
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Franz Saija
- Institute for Physical-Chemical Processes, National Research Council of Italy (IPCF-CNR), Messina, Italy
| | - Giuseppe Cassone
- Institute for Physical-Chemical Processes, National Research Council of Italy (IPCF-CNR), Messina, Italy
| | - Paul B Rimmer
- University of Cambridge, Cavendish Astrophysics, Cambridge, United Kingdom
| | - Martin Ferus
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
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10
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Schaible MJ, Szeinbaum N, Bozdag GO, Chou L, Grefenstette N, Colón-Santos S, Rodriguez LE, Styczinski MJ, Thweatt JL, Todd ZR, Vázquez-Salazar A, Adams A, Araújo MN, Altair T, Borges S, Burton D, Campillo-Balderas JA, Cangi EM, Caro T, Catalano E, Chen K, Conlin PL, Cooper ZS, Fisher TM, Fos SM, Garcia A, Glaser DM, Harman CE, Hermis NY, Hooks M, Johnson-Finn K, Lehmer O, Hernández-Morales R, Hughson KHG, Jácome R, Jia TZ, Marlow JJ, McKaig J, Mierzejewski V, Muñoz-Velasco I, Nural C, Oliver GC, Penev PI, Raj CG, Roche TP, Sabuda MC, Schaible GA, Sevgen S, Sinhadc P, Steller LH, Stelmach K, Tarnas J, Tavares F, Trubl G, Vidaurri M, Vincent L, Weber JM, Weng MM, Wilpiszeki RL, Young A. Chapter 1: The Astrobiology Primer 3.0. ASTROBIOLOGY 2024; 24:S4-S39. [PMID: 38498816 DOI: 10.1089/ast.2021.0129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The Astrobiology Primer 3.0 (ABP3.0) is a concise introduction to the field of astrobiology for students and others who are new to the field of astrobiology. It provides an entry into the broader materials in this supplementary issue of Astrobiology and an overview of the investigations and driving hypotheses that make up this interdisciplinary field. The content of this chapter was adapted from the other 10 articles in this supplementary issue and thus represents the contribution of all the authors who worked on these introductory articles. The content of this chapter is not exhaustive and represents the topics that the authors found to be the most important and compelling in a dynamic and changing field.
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Affiliation(s)
- Micah J Schaible
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Nadia Szeinbaum
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - G Ozan Bozdag
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Luoth Chou
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
- Georgetown University, Washington DC, USA
| | - Natalie Grefenstette
- Santa Fe Institute, Santa Fe, New Mexico, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Stephanie Colón-Santos
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Wisconsin, USA
- Department of Botany, University of Wisconsin-Madison, Wisconsin, USA
| | - Laura E Rodriguez
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - M J Styczinski
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- University of Washington, Seattle, Washington, USA
| | - Jennifer L Thweatt
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania, USA
| | - Zoe R Todd
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Alberto Vázquez-Salazar
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, California, USA
| | - Alyssa Adams
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
| | - M N Araújo
- Biochemistry Department, University of São Paulo, São Carlos, Brazil
| | - Thiago Altair
- Institute of Chemistry of São Carlos, Universidade de São Paulo, São Carlos, Brazil
- Department of Chemistry, College of the Atlantic, Bar Harbor, Maine, USA
| | | | - Dana Burton
- Department of Anthropology, George Washington University, Washington DC, USA
| | | | - Eryn M Cangi
- Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, Colorado, USA
| | - Tristan Caro
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado, USA
| | - Enrico Catalano
- Sant'Anna School of Advanced Studies, The BioRobotics Institute, Pisa, Italy
| | - Kimberly Chen
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter L Conlin
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Z S Cooper
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Theresa M Fisher
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | - Santiago Mestre Fos
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Amanda Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Wisconsin, USA
| | - D M Glaser
- Arizona State University, Tempe, Arizona, USA
| | - Chester E Harman
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ninos Y Hermis
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Department of Physics and Space Sciences, University of Granada, Granada, Spain
| | - M Hooks
- NASA Johnson Space Center, Houston, Texas, USA
| | - K Johnson-Finn
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
- Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Owen Lehmer
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Ricardo Hernández-Morales
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Kynan H G Hughson
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Rodrigo Jácome
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Tony Z Jia
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
| | - Jeffrey J Marlow
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Jordan McKaig
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Veronica Mierzejewski
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | - Israel Muñoz-Velasco
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ceren Nural
- Istanbul Technical University, Istanbul, Turkey
| | - Gina C Oliver
- Department of Geology, San Bernardino Valley College, San Bernardino, California, USA
| | - Petar I Penev
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Chinmayee Govinda Raj
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Tyler P Roche
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Mary C Sabuda
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Biotechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - George A Schaible
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Serhat Sevgen
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin, Turkey
| | - Pritvik Sinhadc
- BEYOND: Center For Fundamental Concepts in Science, Arizona State University, Arizona, USA
- Dubai College, Dubai, United Arab Emirates
| | - Luke H Steller
- Australian Centre for Astrobiology, and School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, Australia
| | - Kamil Stelmach
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - J Tarnas
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Frank Tavares
- Space Enabled Research Group, MIT Media Lab, Cambridge, Massachusetts, USA
| | - Gareth Trubl
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, USA
| | - Monica Vidaurri
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
- Department of Physics and Astronomy, Howard University, Washington DC, USA
| | - Lena Vincent
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Wisconsin, USA
| | - Jessica M Weber
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | | | - Amber Young
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Northern Arizona University, Flagstaff, Arizona, USA
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11
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Borges SR, Jones GG, Robinson TD. Detectability of Surface Biosignatures for Directly Imaged Rocky Exoplanets. ASTROBIOLOGY 2024; 24:283-299. [PMID: 38377582 DOI: 10.1089/ast.2023.0099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Modeling the detection of life has never been more opportune. With next-generation space telescopes, such as the currently developing Habitable Worlds Observatory (HWO) concept, we will begin to characterize rocky exoplanets potentially similar to Earth. However, few realistic planetary spectra containing surface biosignatures have been paired with direct imaging telescope instrument models. Therefore, we use a HWO instrument noise model to assess the detection of surface biosignatures affiliated with oxygenic, anoxygenic, and nonphotosynthetic extremophiles. We pair the HWO telescope model to a one-dimensional radiative transfer model to estimate the required exposure times necessary for detecting each biosignature on planets with global microbial coverage and varying atmospheric water vapor concentrations. For modeled planets with 0-50% cloud coverage, we determine pigments and the red edge could be detected within 1000 hr (100 hr) at distances within 15 pc (11 pc). However, tighter telescope inner working angles (2.5 λ/D) would allow surface biosignature detection at further distances. Anoxygenic photosynthetic biosignatures could also be more easily detectable than nonphotosynthetic pigments and the photosynthetic red edge when compared against a false positive iron oxide slope. Future life detection missions should evaluate the influence of false positives on the detection of multiple surface biosignatures.
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Affiliation(s)
- Schuyler R Borges
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona, USA
- Habitability, Atmospheres, and Biosignatures Laboratory, University of Arizona, Tucson, Arizona, USA
| | - Gabrielle G Jones
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona, USA
- Habitability, Atmospheres, and Biosignatures Laboratory, University of Arizona, Tucson, Arizona, USA
| | - Tyler D Robinson
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona, USA
- Habitability, Atmospheres, and Biosignatures Laboratory, University of Arizona, Tucson, Arizona, USA
- Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
- NASA Nexus for Exoplanet System Science Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
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12
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Chou L, Grefenstette N, Borges S, Caro T, Catalano E, Harman CE, McKaig J, Raj CG, Trubl G, Young A. Chapter 8: Searching for Life Beyond Earth. ASTROBIOLOGY 2024; 24:S164-S185. [PMID: 38498822 DOI: 10.1089/ast.2021.0104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The search for life beyond Earth necessitates a rigorous and comprehensive examination of biosignatures, the types of observable imprints that life produces. These imprints and our ability to detect them with advanced instrumentation hold the key to our understanding of the presence and abundance of life in the universe. Biosignatures are the chemical or physical features associated with past or present life and may include the distribution of elements and molecules, alone or in combination, as well as changes in structural components or physical processes that would be distinct from an abiotic background. The scientific and technical strategies used to search for life on other planets include those that can be conducted in situ to planetary bodies and those that could be observed remotely. This chapter discusses numerous strategies that can be employed to look for biosignatures directly on other planetary bodies using robotic exploration including those that have been deployed to other planetary bodies, are currently being developed for flight, or will become a critical technology on future missions. Search strategies for remote observations using current and planned ground-based and space-based telescopes are also described. Evidence from spectral absorption, emission, or transmission features can be used to search for remote biosignatures and technosignatures. Improving our understanding of biosignatures, their production, transformation, and preservation on Earth can enhance our search efforts to detect life on other planets.
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Affiliation(s)
- Luoth Chou
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
- Georgetown University, Washington, DC, USA
| | - Natalie Grefenstette
- Santa Fe Institute, Santa Fe, New Mexico, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | | | - Tristan Caro
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado, USA
| | - Enrico Catalano
- Sant'Anna School of Advanced Studies, The BioRobotics Institute, Pisa, Italy
| | | | - Jordan McKaig
- Georgia Institute of Technology, Atlanta, Georgia, USA
| | | | - Gareth Trubl
- Lawrence Livermore National Laboratory, Livermore, California, USA
| | - Amber Young
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Northern Arizona University, Flagstaff, Arizona, USA
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13
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Shapshak P, Zandi M, Somboonwit C, T. Sinnott J. Astrovirology and terrestrial life survival. Bioinformation 2024; 20:146-150. [PMID: 38497066 PMCID: PMC10941782 DOI: 10.6026/973206300200146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 03/19/2024] Open
Abstract
Microbial organisms have been implicated in several mass extinction events throughout Earth's planetary history. Concurrently, it can be reasoned from recent viral pandemics that viruses likely exacerbated the decline of life during these periods of mass extinction. The fields of exovirology and exobiology have evolved significantly since the 20th century, with early investigations into the varied atmospheric compositions of exoplanets revealing complex interactions between metallic and non-metallic elements. This diversity in exoplanetary and stellar environments suggests that life could manifest in forms previously unanticipated by earlier, more simplistic models of the 20th century. Non-linear theories of complexity, catastrophe, and chaos (CCC) will be important in understanding the dynamics and evolution of viruses.
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Affiliation(s)
- Paul Shapshak
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
| | - Milad Zandi
- Hepatitis Research Center, Department of Virology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, IRAN
| | - Charurut Somboonwit
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
| | - John T. Sinnott
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
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14
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Shapshak P, Zandi M, Somboonwit C, Sinnott JT. Neutrinos to Astrovirology: Signatures. Bioinformation 2024; 20:18-19. [PMID: 38352902 PMCID: PMC10859944 DOI: 10.6026/973206300200018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/16/2024] Open
Abstract
In the 20th century, the concept of terrestrial life's unity was solidified, and the 21st century saw the emergence and establishment of astrovirology. To date, life originating beyond Earth has not been identified. The singular instance where NASA investigated potential microfossils in Martian ejecta found on Earth has since been refuted. This report suggests that a more comprehensive discussion and analysis of life's biosignatures and communication methods are essential. Such approaches are crucial not only to avoid overlooking the possible existence of extra-terrestrial intelligence (ETI) but also to prevent potential human infections that could arise from extra-terrestrial contact. In addition terrestrial infections by microorganism that originally derived from Earth and were returned, require investigation due to potential mutations and subsequent increased pathogenicity.
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Affiliation(s)
- Paul Shapshak
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
| | - Milad Zandi
- Hepatitis Research Center, Department of Virology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Charurut Somboonwit
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
| | - John T Sinnott
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33606, USA
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15
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Maggiori C, Fernández-Martínez MA, Bourdages LJ, Sánchez-García L, Moreno-Paz M, Sobrado JM, Carrizo D, Vicente-Retortillo Á, Goordial J, Whyte LG. Biosignature Detection and MinION Sequencing of Antarctic Cryptoendoliths After Exposure to Mars Simulation Conditions. ASTROBIOLOGY 2024; 24:44-60. [PMID: 38153386 DOI: 10.1089/ast.2023.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
In the search for life in our Solar System, Mars remains a promising target based on its proximity and similarity to Earth. When Mars transitioned from a warmer, wetter climate to its current dry and freezing conditions, any putative extant life probably retreated into habitable refugia such as the subsurface or the interior of rocks. Terrestrial cryptoendolithic microorganisms (i.e., those inhabiting rock interiors) thus represent possible modern-day Mars analogs, particularly those from the hyperarid McMurdo Dry Valleys in Antarctica. As DNA is a strong definitive biosignature, given that there is no known abiotic chemistry that can polymerize nucleobases, we investigated DNA detection with MinION sequencing in Antarctic cryptoendoliths after an ∼58-sol exposure in MARTE, a Mars environmental chamber capable of simulating martian temperature, pressure, humidity, ultraviolet (UV) radiation, and atmospheric composition, in conjunction with protein and lipid detection. The MARTE conditions resulted in changes in community composition and DNA, proteins, and cell membrane-derived lipids remained detectable postexposure. Of the multitude of extreme environmental conditions on Mars, UV radiation (specifically UVC) is the most destructive to both cells and DNA. As such, we further investigated if a UVC exposure corresponding to ∼278 martian years would impede DNA detection via MinION sequencing. The MinION was able to successfully detect and sequence DNA after this UVC radiation exposure, suggesting its utility for life detection in future astrobiology missions focused on finding relatively recently exposed biomarkers inside possible martian refugia.
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Affiliation(s)
- Catherine Maggiori
- Department of Biology, Georgetown University, Washington, District of Columbia, USA
| | - Miguel Angel Fernández-Martínez
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne-de-Bellevue, Quebec, Canada
- Department of Ecology, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, Madrid, Spain
| | - Louis-Jacques Bourdages
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne-de-Bellevue, Quebec, Canada
| | | | | | | | | | | | - Jacqueline Goordial
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Lyle G Whyte
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne-de-Bellevue, Quebec, Canada
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16
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Siliprandi J, MacLachlan DG, Ross CA, Sharma TK, Labadie L, Madhav K, Nayak AS, Dinkelaker AN, Roth MM, Scott NJ, du Foresto VC, Thomson RR, Benoit A. Fiber-connectorized ultrafast-laser-inscribed K-band integrated optics beam combiner for the CHARA telescope array. APPLIED OPTICS 2024; 63:159-166. [PMID: 38175017 DOI: 10.1364/ao.510293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 11/28/2023] [Indexed: 01/05/2024]
Abstract
A fiber-connectorized K-band integrated-optics two-telescope beam combiner was developed for long-baseline interferometry at the CHARA telescope array utilizing the ultrafast laser inscription (ULI) technique. Single-mode waveguide insertion losses were measured to be ∼1.1d B over the 2-2.3 µm window. The development of asymmetric directional couplers enabled the construction of a beam combiner that includes a 50:50 coupler for interferometric combination and two ∼75:25 couplers for photometric calibration. The visibility of the bare beam combiner was measured at 87% and then at 82% after fiber-connectorization by optimizing the input polarization. These results indicate that ULI technique can fabricate efficient fiber-connectorized K-band beam combiners for astronomical purposes.
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17
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Luo Y, Hu Y, Yang J, Zhang M, Yung YL. Coupled atmospheric chemistry, radiation, and dynamics of an exoplanet generate self-sustained oscillations. Proc Natl Acad Sci U S A 2023; 120:e2309312120. [PMID: 38091286 PMCID: PMC10743409 DOI: 10.1073/pnas.2309312120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 10/13/2023] [Indexed: 12/24/2023] Open
Abstract
Nonlinearity in photochemical systems is known to allow self-sustained oscillations, but they have received little attention in studies of planetary atmospheres. Here, we present a unique, self-oscillatory solution for ozone chemistry of an exoplanet from a numerical simulation using a fully coupled, three-dimensional (3D) atmospheric chemistry-radiation-dynamics model. Forced with nonvarying stellar insolation and emission flux of nitric oxide (NO), atmospheric ozone abundance oscillates by a factor of thirty over a multidecadal timescale. As such self-oscillations can only occur with biological nitrogen fixation contributing to NO emission, we propose that they are a unique class of biosignature. The resulting temporal variability in the atmospheric spectrum is potentially observable. Our results underscore the importance of revisiting the spectra of exoplanets over multidecadal timescales to characterizing the atmospheric chemistry of exoplanets and searching for exoplanet biosignatures. There are also profound implications for comparative planetology and the evolution of the atmospheres of terrestrial planets in the solar system and beyond. Fully coupled, 3D atmospheric chemistry-radiation-dynamics models can reveal new phenomena that may not exist in one-dimensional models, and hence, they are powerful tools for future planetary atmospheric research.
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Affiliation(s)
- Yangcheng Luo
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA91125
- Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing100871, China
- Laboratoire de Météorologie Dynamique/Institut Pierre-Simon Laplace, Sorbonne Université, École Normale Supérieure, Université Paris Sciences et Lettres, Ecole Polytechnique, Institut Polytechnique de Paris, Centre National de la Recherche Scientifique, Paris75005, France
| | - Yongyun Hu
- Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing100871, China
| | - Jun Yang
- Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing100871, China
| | - Michael Zhang
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA91125
| | - Yuk L. Yung
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA91125
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18
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Campargue A, Karlovets EV, Vasilchenko SS, Turbet M. The high resolution absorption spectrum of methane in the 10 800-14 000 cm -1 region: literature review, new results and perspectives. Phys Chem Chem Phys 2023. [PMID: 38038983 DOI: 10.1039/d3cp02385k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
The recent development of high resolution spectrographs for exoplanetary research in the visible range makes suitable an improvement of our knowledge of the high resolution spectrum of methane. In this contribution, the weak and highly congested absorption spectrum of methane in the 10 800-14 000 cm-1 region (0.71-0.93 μm) is considered on the basis of (i) an exhaustive review of the literature over the lasts decades, (ii) the analysis of a spectrum recorded at Kitt Peak by Fourier transform spectroscopy at room temperature, (iii) a very high sensitivity spectrum recorded by cavity ring down spectroscopy near 760 nm. The line list retrieved from the Kitt Peak spectrum includes 12 800 lines between 10 802 and 13 922 cm-1. Together with the CRDS line list in the 13 060-13 300 cm-1 interval (about 2650 lines), the reported FTS dataset represents the first high resolution extensive intensity measurements of methane for wavenumbers above 11 502 cm-1. A very good agreement between our Kitt Peak line list and HITRAN list is found in the 10 800-11 502 cm-1 interval. The "quasi-continuum" absorption background underlying the congested spectrum around 11 200 cm-1 is quantitatively evaluated to about 42% of the absorption by CH4 lines. Previous laser-based investigations are critically reviewed by comparison to the FTS and CRDS experimental data retrieved in the present work. The review of the studies of the minor isotopologues (13CH4, CH3D, CH2D2, and CHD3) is also presented. Intensity comparison with band models used for planetary applications is discussed and confirms the importance of the "quasi-continuum" absorption in the methane spectrum at room temperature. The comparison to the TheoReTs line list obtained by ab initio calculations gives valuable hints for future assignments but the TheoReTS line positions are not sufficiently accurate for application to high resolution exoplanetary spectra in the region. From the various comparisons and results obtained in this work, we conclude that the high frequency absorption spectrum of methane deserves to be revisited by modern cavity-enhanced absorption techniques to fulfil needs both for future analysis of high resolution exoplanetary spectra and for theoretical analysis.
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Affiliation(s)
- A Campargue
- University Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France.
| | - E V Karlovets
- Tomsk State University, Department of Optics and Spectroscopy, 36, Lenin Avenue, 634050, Tomsk, Russia
| | - S S Vasilchenko
- V.E. Zuev Institute of Atmospheric Optics, 1, Academician Zuev Square, 634055 Tomsk, Russia
| | - M Turbet
- Laboratoire de Météorologie Dynamique/IPSL, CNRS, Sorbonne Université, École Normale Supérieure, Université PSL, Ecole Polytechnique, Institut Polytechnique de Paris, 75005 Paris, France
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19
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Smith HB, Mathis C. Life detection in a universe of false positives: Can the Fatal Flaws of Exoplanet Biosignatures be Overcome Absent a Theory of Life? Bioessays 2023; 45:e2300050. [PMID: 37821360 DOI: 10.1002/bies.202300050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 09/24/2023] [Accepted: 09/27/2023] [Indexed: 10/13/2023]
Abstract
Astrobiology aims to determine the distribution and diversity of life in the universe. But as the word "biosignature" suggests, what will be detected is not life itself, but an observation implicating living systems. Our limited access to other worlds suggests this observation is more likely to reflect out-of-equilibrium gasses than a writhing octopus. Yet, anything short of a writhing octopus will raise skepticism about what has been detected. Resolving that skepticism requires a theory to delineate processes due to life and those due to abiotic mechanisms. This poses an existential question for life detection: How do astrobiologists plan to detect life on exoplanets via features shared between non-living and living systems? We argue that you cannot without an underlying theory of life. We illustrate this by analyzing the hypothetical detection of an "Earth 2.0" exoplanet. Without a theory of life, we argue the community should focus on identifying unambiguous features of life via four areas: examining life on Earth, building life in the lab, probing the solar system, and searching for technosignatures. Ultimately, we ask, what exactly do astrobiologists hope to learn by searching for life?
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Affiliation(s)
- Harrison B Smith
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Cole Mathis
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona, USA
- Santa Fe Institute, Santa Fe, New Mexico, USA
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20
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Brown SM, Mayer-Bacon C, Freeland S. Xeno Amino Acids: A Look into Biochemistry as We Do Not Know It. Life (Basel) 2023; 13:2281. [PMID: 38137883 PMCID: PMC10744825 DOI: 10.3390/life13122281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/18/2023] [Accepted: 11/20/2023] [Indexed: 12/24/2023] Open
Abstract
Would another origin of life resemble Earth's biochemical use of amino acids? Here, we review current knowledge at three levels: (1) Could other classes of chemical structure serve as building blocks for biopolymer structure and catalysis? Amino acids now seem both readily available to, and a plausible chemical attractor for, life as we do not know it. Amino acids thus remain important and tractable targets for astrobiological research. (2) If amino acids are used, would we expect the same L-alpha-structural subclass used by life? Despite numerous ideas, it is not clear why life favors L-enantiomers. It seems clearer, however, why life on Earth uses the shortest possible (alpha-) amino acid backbone, and why each carries only one side chain. However, assertions that other backbones are physicochemically impossible have relaxed into arguments that they are disadvantageous. (3) Would we expect a similar set of side chains to those within the genetic code? Many plausible alternatives exist. Furthermore, evidence exists for both evolutionary advantage and physicochemical constraint as explanatory factors for those encoded by life. Overall, as focus shifts from amino acids as a chemical class to specific side chains used by post-LUCA biology, the probable role of physicochemical constraint diminishes relative to that of biological evolution. Exciting opportunities now present themselves for laboratory work and computing to explore how changing the amino acid alphabet alters the universe of protein folds. Near-term milestones include: (a) expanding evidence about amino acids as attractors within chemical evolution; (b) extending characterization of other backbones relative to biological proteins; and (c) merging computing and laboratory explorations of structures and functions unlocked by xeno peptides.
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21
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Vickers P, Cowie C, Dick SJ, Gillen C, Jeancolas C, Rothschild LJ, McMahon S. Confidence of Life Detection: The Problem of Unconceived Alternatives. ASTROBIOLOGY 2023; 23:1202-1212. [PMID: 37506351 DOI: 10.1089/ast.2022.0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Potential biosignatures that offer the promise of extraterrestrial life (past or present) are to be expected in the coming years and decades, whether from within our own solar system, from an exoplanet atmosphere, or otherwise. With each such potential biosignature, the degree of our uncertainty will be the first question asked. Have we really identified extraterrestrial life? How sure are we? This paper considers the problem of unconceived alternative explanations. We stress that articulating our uncertainty requires an assessment of the extent to which we have explored the relevant possibility space. It is argued that, for most conceivable potential biosignatures, we currently have not explored the relevant possibility space very thoroughly at all. Not only does this severely limit the circumstances in which we could reasonably be confident in our detection of extraterrestrial life, it also poses a significant challenge to any attempt to quantify our degree of uncertainty. The discussion leads us to the following recommendation: when it comes specifically to an extraterrestrial life-detection claim, the astrobiology community should follow the uncertainty assessment approach adopted by the Intergovernmental Panel on Climate Change (IPCC).
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Affiliation(s)
| | | | - Steven J Dick
- NASA Chief Historian (Retired), NASA, Washington, DC, USA
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22
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Malaterre C, Ten Kate IL, Baqué M, Debaille V, Grenfell JL, Javaux EJ, Khawaja N, Klenner F, Lara YJ, McMahon S, Moore K, Noack L, Patty CHL, Postberg F. Is There Such a Thing as a Biosignature? ASTROBIOLOGY 2023; 23:1213-1227. [PMID: 37962841 DOI: 10.1089/ast.2023.0042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The concept of a biosignature is widely used in astrobiology to suggest a link between some observation and a biological cause, given some context. The term itself has been defined and used in several ways in different parts of the scientific community involved in the search for past or present life on Earth and beyond. With the ongoing acceleration in the search for life in distant time and/or deep space, there is a need for clarity and accuracy in the formulation and reporting of claims. Here, we critically review the biosignature concept(s) and the associated nomenclature in light of several problems and ambiguities emphasized by recent works. One worry is that these terms and concepts may imply greater certainty than is usually justified by a rational interpretation of the data. A related worry is that terms such as "biosignature" may be inherently misleading, for example, because the divide between life and non-life-and their observable effects-is fuzzy. Another worry is that different parts of the multidisciplinary community may use non-equivalent or conflicting definitions and conceptions, leading to avoidable confusion. This review leads us to identify a number of pitfalls and to suggest how they can be circumvented. In general, we conclude that astrobiologists should exercise particular caution in deciding whether and how to use the concept of biosignature when thinking and communicating about habitability or life. Concepts and terms should be selected carefully and defined explicitly where appropriate. This would improve clarity and accuracy in the formulation of claims and subsequent technical and public communication about some of the most profound and important questions in science and society. With this objective in mind, we provide a checklist of questions that scientists and other interested parties should ask when assessing any reported detection of a "biosignature" to better understand exactly what is being claimed.
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Affiliation(s)
- Christophe Malaterre
- Département de philosophie, Chaire de recherche du Canada en philosophie des sciences de la vie, Université du Québec à Montréal (UQAM), Montréal, Québec, Canada
- Centre interuniversitaire de recherche sur la science et la technologie (CIRST), Université du Québec à Montréal (UQAM), Montréal, Québec, Canada
| | - Inge Loes Ten Kate
- Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
| | - Mickael Baqué
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - Vinciane Debaille
- Laboratoire G-Time, Université libre de Bruxelles, Brussels, Belgium
| | - John Lee Grenfell
- Department of Extrasolar Planets and Atmospheres, Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - Emmanuelle J Javaux
- Early Life Traces & Evolution-Astrobiology, UR Astrobiology, University of Liège, Liège, Belgium
| | - Nozair Khawaja
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Fabian Klenner
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Yannick J Lara
- Early Life Traces & Evolution-Astrobiology, UR Astrobiology, University of Liège, Liège, Belgium
| | - Sean McMahon
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Keavin Moore
- Department of Earth & Planetary Sciences, McGill University, Montreal, Québec, Canada
- Trottier Space Institute, McGill University, Montreal, Québec, Canada
| | - Lena Noack
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - C H Lucas Patty
- Physikalisches Institut, Universität Bern, Bern, Switzerland
- Center for Space and Habitability, Universität Bern, Bern, Switzerland
| | - Frank Postberg
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
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23
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Gillen C, Jeancolas C, McMahon S, Vickers P. The Call for a New Definition of Biosignature. ASTROBIOLOGY 2023; 23:1228-1237. [PMID: 37819715 DOI: 10.1089/ast.2023.0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The term biosignature has become increasingly prevalent in astrobiology literature as our ability to search for life advances. Although this term has been useful to the community, its definition is not settled. Existing definitions conflict sharply over the balance of evidence needed to establish a biosignature, which leads to misunderstanding and confusion about what is being claimed when biosignatures are purportedly detected. To resolve this, we offer a new definition of a biosignature as any phenomenon for which biological processes are a known possible explanation and whose potential abiotic causes have been reasonably explored and ruled out. This definition is strong enough to do the work required of it in multiple contexts-from the search for life on Mars to exoplanet spectroscopy-where the quality and indeed quantity of obtainable evidence is markedly different. Moreover, it addresses the pernicious problem of unconceived abiotic mimics that is central to biosignature research. We show that the new definition yields intuitively satisfying judgments when applied to historical biosignature claims. We also reaffirm the importance of multidisciplinary work on abiotic mimics to narrow the gap between the detection of a biosignature and a confirmed discovery of life.
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Cleaves HJ, Hystad G, Prabhu A, Wong ML, Cody GD, Economon S, Hazen RM. A robust, agnostic molecular biosignature based on machine learning. Proc Natl Acad Sci U S A 2023; 120:e2307149120. [PMID: 37748080 PMCID: PMC10576141 DOI: 10.1073/pnas.2307149120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/17/2023] [Indexed: 09/27/2023] Open
Abstract
The search for definitive biosignatures-unambiguous markers of past or present life-is a central goal of paleobiology and astrobiology. We used pyrolysis-gas chromatography coupled to mass spectrometry to analyze chemically disparate samples, including living cells, geologically processed fossil organic material, carbon-rich meteorites, and laboratory-synthesized organic compounds and mixtures. Data from each sample were employed as training and test subsets for machine-learning methods, which resulted in a model that can identify the biogenicity of both contemporary and ancient geologically processed samples with ~90% accuracy. These machine-learning methods do not rely on precise compound identification: Rather, the relational aspects of chromatographic and mass peaks provide the needed information, which underscores this method's utility for detecting alien biology.
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Affiliation(s)
- H. James Cleaves
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Earth Life Science Institute, Tokyo Institute of Technology, Tokyo152-8550, Japan
- Blue Marble Space Institute for Science, Seattle, WA98104
| | - Grethe Hystad
- Department of Mathematics and Statistics, Purdue University Northwest, Hammond, IN46323
| | - Anirudh Prabhu
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
| | - Michael L. Wong
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Sagan Fellow, NASA Hubble Fellowship Program, Space Telescope Science Institute, Baltimore, MD21218
| | - George D. Cody
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
| | - Sophia Economon
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD21218
| | - Robert M. Hazen
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
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Trubl G, Stedman KM, Bywaters KF, Matula EE, Sommers P, Roux S, Merino N, Yin J, Kaelber JT, Avila-Herrera A, Johnson PA, Johnson JC, Borges S, Weber PK, Pett-Ridge J, Boston PJ. Astrovirology: how viruses enhance our understanding of life in the Universe. INTERNATIONAL JOURNAL OF ASTROBIOLOGY 2023; 22:247-271. [PMID: 38046673 PMCID: PMC10691837 DOI: 10.1017/s1473550423000058] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Viruses are the most numerically abundant biological entities on Earth. As ubiquitous replicators of molecular information and agents of community change, viruses have potent effects on the life on Earth, and may play a critical role in human spaceflight, for life-detection missions to other planetary bodies and planetary protection. However, major knowledge gaps constrain our understanding of the Earth's virosphere: (1) the role viruses play in biogeochemical cycles, (2) the origin(s) of viruses and (3) the involvement of viruses in the evolution, distribution and persistence of life. As viruses are the only replicators that span all known types of nucleic acids, an expanded experimental and theoretical toolbox built for Earth's viruses will be pivotal for detecting and understanding life on Earth and beyond. Only by filling in these knowledge and technical gaps we will obtain an inclusive assessment of how to distinguish and detect life on other planetary surfaces. Meanwhile, space exploration requires life-support systems for the needs of humans, plants and their microbial inhabitants. Viral effects on microbes and plants are essential for Earth's biosphere and human health, but virus-host interactions in spaceflight are poorly understood. Viral relationships with their hosts respond to environmental changes in complex ways which are difficult to predict by extrapolating from Earth-based proxies. These relationships should be studied in space to fully understand how spaceflight will modulate viral impacts on human health and life-support systems, including microbiomes. In this review, we address key questions that must be examined to incorporate viruses into Earth system models, life-support systems and life detection. Tackling these questions will benefit our efforts to develop planetary protection protocols and further our understanding of viruses in astrobiology.
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Affiliation(s)
- Gareth Trubl
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Kenneth M. Stedman
- Center for Life in Extreme Environments, Department of Biology, Portland State University, Portland, OR, USA
| | | | | | | | - Simon Roux
- DOE Joint Genome Institute, Berkeley, CA, USA
| | - Nancy Merino
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - John Yin
- Chemical and Biological Engineering, Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
| | - Jason T. Kaelber
- Institute for Quantitative Biomedicine, Rutgers, the State University of New Jersey, Piscataway, NJ, USA
| | - Aram Avila-Herrera
- Computing Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Peter Anto Johnson
- Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada
| | | | | | - Peter K. Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
- Life & Environmental Sciences Department, University of California Merced, Merced, CA, USA
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Battistuzzi M, Cocola L, Liistro E, Claudi R, Poletto L, La Rocca N. Growth and Photosynthetic Efficiency of Microalgae and Plants with Different Levels of Complexity Exposed to a Simulated M-Dwarf Starlight. Life (Basel) 2023; 13:1641. [PMID: 37629498 PMCID: PMC10455698 DOI: 10.3390/life13081641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/16/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
Oxygenic photosynthetic organisms (OPOs) are primary producers on Earth and generate surface and atmospheric biosignatures, making them ideal targets to search for life from remote on Earth-like exoplanets orbiting stars different from the Sun, such as M-dwarfs. These stars emit very low light in the visible and most light in the far-red, an issue for OPOs, which mostly utilize visible light to photosynthesize and grow. After successfully testing procaryotic OPOs (cyanobacteria) under a simulated M-dwarf star spectrum (M7, 365-850 nm) generated through a custom-made lamp, we tested several eukaryotic OPOs: microalgae (Dixoniella giordanoi, Microchloropsis gaditana, Chromera velia, Chlorella vulgaris), a non-vascular plant (Physcomitrium patens), and a vascular plant (Arabidopsis thaliana). We assessed their growth and photosynthetic efficiency under three light conditions: M7, solar (SOL) simulated spectra, and far-red light (FR). Microalgae grew similarly in SOL and M7, while the moss P. patens showed slower growth in M7 with respect to SOL. A. thaliana grew similarly in SOL and M7, showing traits typical of shade-avoidance syndrome. Overall, the synergistic effect of visible and far-red light, also known as the Emerson enhancing effect, could explain the growth in M7 for all organisms. These results lead to reconsidering the possibility and capability of the growth of OPOs and are promising for finding biosignatures on exoplanets orbiting the habitable zone of distant stars.
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Affiliation(s)
- Mariano Battistuzzi
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), 35131 Padua, Italy; (L.C.)
- Department of Biology, University of Padua, 35121 Padua, Italy (N.L.R.)
- Center for Space Studies and Activities (CISAS), University of Padua, 35131 Padua, Italy
| | - Lorenzo Cocola
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), 35131 Padua, Italy; (L.C.)
| | | | - Riccardo Claudi
- National Institute for Astrophysics (INAF), Astronomical Observatory of Padua, 35122 Padua, Italy
- Department of Mathematics and Physics, University Roma Tre, 00146 Rome, Italy
| | - Luca Poletto
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), 35131 Padua, Italy; (L.C.)
| | - Nicoletta La Rocca
- Department of Biology, University of Padua, 35121 Padua, Italy (N.L.R.)
- Center for Space Studies and Activities (CISAS), University of Padua, 35131 Padua, Italy
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Seeburger R, Higgins PM, Whiteford NP, Cockell CS. Linking Methanogenesis in Low-Temperature Hydrothermal Vent Systems to Planetary Spectra: Methane Biosignatures on an Archean-Earth-like Exoplanet. ASTROBIOLOGY 2023; 23:415-430. [PMID: 37017441 DOI: 10.1089/ast.2022.0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, the viability of the detection of methane produced by microbial activity in low-temperature hydrothermal vents on an Archean-Earth-like exoplanet in the habitable zone is explored via a simplified bottom-up approach using a toy model. By simulating methanogens at hydrothermal vent sites in the deep ocean, biological methane production for a range of substrate inflow rates was determined and compared to literature values. These production rates were then used, along with a range of ocean floor vent coverage fractions, to determine likely methane concentrations in the simplified atmosphere. At maximum production rates, a vent coverage of 4-15 × 10-4 % (roughly 2000-6500 times that of modern Earth) is required to achieve 0.25% atmospheric methane. At minimum production rates, 100% vent coverage is not enough to produce 0.25% atmospheric methane. NASA's Planetary Spectrum Generator was then used to assess the detectability of methane features at various atmospheric concentrations. Even with future space-based observatory concepts (such as LUVOIR and HabEx), our results show the importance of both mirror size and distance to the observed planet. Planets with a substantial biomass of methanogens in hydrothermal vents can still lack a detectable, convincingly biological methane signature if they are beyond the scope of the chosen instrument. This work shows the value of coupling microbial ecological modeling with exoplanet science to better understand the constraints on biosignature gas production and its detectability.
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Affiliation(s)
- Rhys Seeburger
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Max Planck Institute for Astronomy, Heidelberg, Germany
| | - Peter M Higgins
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Department of Earth Sciences, University of Toronto, Toronto, Canada
| | - Niall P Whiteford
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Centre for Exoplanet Science, University of Edinburgh, Edinburgh, UK
- American Museum of Natural History, New York, New York, USA
| | - Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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Distinguishing Biotic vs. Abiotic Origins of ‘Bio’signatures: Clues from Messy Prebiotic Chemistry for Detection of Life in the Universe. Life (Basel) 2023; 13:life13030766. [PMID: 36983921 PMCID: PMC10058490 DOI: 10.3390/life13030766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/04/2023] [Accepted: 03/11/2023] [Indexed: 03/16/2023] Open
Abstract
It is not a stretch to say that the search for extraterrestrial life is possibly the biggest of the cosmic endeavors that humankind has embarked upon. With the continued discovery of several Earth-like exoplanets, the hope of detecting potential biosignatures is multiplying amongst researchers in the astrobiology community. However, to be able to discern these signatures as being truly of biological origin, we also need to consider their probable abiotic origin. The field of prebiotic chemistry, which is aimed at understanding enzyme-free chemical syntheses of biologically relevant molecules, could particularly aid in this regard. Specifically, certain peculiar characteristics of prebiotically pertinent messy chemical reactions, including diverse and racemic product yields and lower synthesis efficiencies, can be utilized in analyzing whether a perceived ‘signature of life’ could possibly have chemical origins. The knowledge gathered from understanding the transition from chemistry to biology during the origin of life could be used for creating a library of abiotically synthesized biologically relevant organic molecules. This can then be employed in designing, standardizing, and testing mission-specific instruments/analysis systems, while also enabling the effective targeting of exoplanets with potentially ‘ongoing’ molecular evolutionary processes for robust detection of life in future explorative endeavors.
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Corenblit D, Decaux O, Delmotte S, Toumazet JP, Arrignon F, André MF, Darrozes J, Davies NS, Julien F, Otto T, Ramillien G, Roussel E, Steiger J, Viles H. Signatures of Life Detected in Images of Rocks Using Neural Network Analysis Demonstrate New Potential for Searching for Biosignatures on the Surface of Mars. ASTROBIOLOGY 2023; 23:308-326. [PMID: 36668995 DOI: 10.1089/ast.2022.0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Microorganisms play a role in the construction or modulation of various types of landforms. They are especially notable for forming microbially induced sedimentary structures (MISS). Such microbial structures have been considered to be among the most likely biosignatures that might be encountered on the martian surface. Twenty-nine algorithms have been tested with images taken during a laboratory experiment for testing their performance in discriminating mat cracks (MISS) from abiotic mud cracks. Among the algorithms, neural network types produced excellent predictions with similar precision of 0.99. Following that step, a convolutional neural network (CNN) approach has been tested to see whether it can conclusively detect MISS in images of rocks and sediment surfaces taken at different natural sites where present and ancient (fossil) microbial mat cracks and abiotic desiccation cracks were observed. The CNN approach showed excellent prediction of biotic and abiotic structures from the images (global precision, sensitivity, and specificity, respectively, 0.99, 0.99, and 0.97). The key areas of interest of the machine matched well with human expertise for distinguishing biotic and abiotic forms (in their geomorphological meaning). The images indicated clear differences between the abiotic and biotic situations expressed at three embedded scales: texture (size, shape, and arrangement of the grains constituting the surface of one form), form (outer shape of one form), and pattern of form arrangement (arrangement of the forms over a few square meters). The most discriminative components for biogenicity were the border of the mat cracks with their tortuous enlarged and blistered morphology more or less curved upward, sometimes with thin laminations. To apply this innovative biogeomorphological approach to the images obtained by rovers on Mars, the main physical and biological sources of variation in abiotic and biotic outcomes must now be further considered.
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Affiliation(s)
- Dov Corenblit
- Université Clermont Auvergne, CNRS, GEOLAB, Clermont-Ferrand, France
- CNRS, Laboratoire écologie fonctionnelle et environnement, Université Paul Sabatier, CNRS, INPT, UPS, Toulouse, France
| | | | | | | | | | | | - José Darrozes
- Université Paul Sabatier, CNRS/IRD, GET, Toulouse, France
| | - Neil S Davies
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Frédéric Julien
- CNRS, Laboratoire écologie fonctionnelle et environnement, Université Paul Sabatier, CNRS, INPT, UPS, Toulouse, France
| | - Thierry Otto
- CNRS, Laboratoire écologie fonctionnelle et environnement, Université Paul Sabatier, CNRS, INPT, UPS, Toulouse, France
| | | | - Erwan Roussel
- Université Clermont Auvergne, CNRS, GEOLAB, Clermont-Ferrand, France
| | - Johannes Steiger
- Université Clermont Auvergne, CNRS, GEOLAB, Clermont-Ferrand, France
| | - Heather Viles
- School of Geography and the Environment, University of Oxford, Oxford, United Kingdom
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Spectroscopic Detection of Biosignatures in Natural Ice Samples as a Proxy for Icy Moons. Life (Basel) 2023; 13:life13020478. [PMID: 36836835 PMCID: PMC9960113 DOI: 10.3390/life13020478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 01/29/2023] [Accepted: 02/04/2023] [Indexed: 02/11/2023] Open
Abstract
Some of the icy moons of the solar system with a subsurface ocean, such as Europa and Enceladus, are the targets of future space missions that search for potential extraterrestrial life forms. While the ice shells that envelop these moons have been studied by several spacecrafts, the oceans beneath them remain unreachable. To better constrain the habitability conditions of these moons, we must understand the interactions between their frozen crusts, liquid layers, and silicate mantles. To that end, astrobiologists rely on planetary field analogues, for which the polar regions of Earth have proven to be great candidates. This review shows how spectroscopy is a powerful tool in space missions to detect potential biosignatures, in particular on the aforementioned moons, and how the polar regions of the Earth are being used as planetary field analogues for these extra-terrestrial environments.
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Battistuzzi M, Cocola L, Claudi R, Pozzer AC, Segalla A, Simionato D, Morosinotto T, Poletto L, La Rocca N. Oxygenic photosynthetic responses of cyanobacteria exposed under an M-dwarf starlight simulator: Implications for exoplanet's habitability. FRONTIERS IN PLANT SCIENCE 2023; 14:1070359. [PMID: 36824196 PMCID: PMC9941696 DOI: 10.3389/fpls.2023.1070359] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
INTRODUCTION The search for life on distant exoplanets is expected to rely on atmospheric biosignatures detection, such as oxygen of biological origin. However, it is not demonstrated how much oxygenic photosynthesis, which on Earth depends on visible light, could work under spectral conditions simulating exoplanets orbiting the Habitable Zone of M-dwarf stars, which have low light emission in the visible and high light emission in the far-red/near-infrared. By utilizing cyanobacteria, the first organisms to evolve oxygenic photosynthesis on our planet, and a starlight simulator capable of accurately reproducing the emission spectrum of an M-dwarf in the range 350-900 nm, we could answer this question. METHODS We performed experiments with the cyanobacterium Chlorogloeopsis fritschii PCC6912, capable of Far-Red Light Photoacclimation (FaRLiP), which allows the strain to harvest far-red in addition to visible light for photosynthesis, and Synechocystis sp. PCC6803, a species unable to perform this photoacclimation, comparing their responses when exposed to three simulated light spectra: M-dwarf, solar and far-red. We analysed growth and photosynthetic acclimation features in terms of pigment composition and photosystems organization. Finally, we determined the oxygen production of the strains directly exposed to the different spectra. RESULTS Both cyanobacteria were shown to grow and photosynthesize similarly under M-dwarf and solar light conditions: Synechocystis sp. by utilizing the few photons in the visible, C. fritschii by harvesting both visible and far-red light, activating the FaRLiP response. DISCUSSION Our results experimentally show that an M-dwarf light spectrum could support a biological oxygen production similar to that in solar light at the tested light intensities, suggesting the possibility to discover such atmospheric biosignatures on those exoplanets if other boundary conditions are met.
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Affiliation(s)
- Mariano Battistuzzi
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
| | - Lorenzo Cocola
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), Padua, Italy
| | - Riccardo Claudi
- National Institute for Astrophysics, Astronomical Observatory of Padua (INAF-OAPD), Padua, Italy
| | - Anna Caterina Pozzer
- Department of Biology, University of Padua, Padua, Italy
- National Institute for Astrophysics, Astronomical Observatory of Padua (INAF-OAPD), Padua, Italy
| | - Anna Segalla
- Department of Biology, University of Padua, Padua, Italy
| | | | - Tomas Morosinotto
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
| | - Luca Poletto
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), Padua, Italy
| | - Nicoletta La Rocca
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
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Kim K, Kim C, Yoo J, Kim JR, Kim YH, Lee SE. Phosphine gas in the dark induces severe phytotoxicity in Arabidopsis thaliana by increasing a hypoxia stress response and disrupting the energy metabolism: Transcriptomic approaches. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130141. [PMID: 36241498 DOI: 10.1016/j.jhazmat.2022.130141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Phosphine (PH3) is an ideal fumigant alternative on methyl bromide (MB) as MB has been classified as an ozone-depleting substance. However, several challenges limit its efficient use in crop production, including the emergence of PH3-resistant insect pests and the incidence of phytotoxic effects on nursery plants. Therefore, this study aims to elucidate the mechanism underlying PH3 phytotoxicity in plants using transcriptomic techniques. Fumigation with 2 g/m3 PH3 induced phytotoxic effects in A. thaliana, as evidenced by a decrease in growth and vegetation indices compared to the control group. Transcriptomic analysis revealed that PH3 fumigation phytotoxicity responses in A. thaliana involve genes related to hypoxia stress and energy metabolism. Additionally, pretreatment with ethylene induced pre-adaptation to hypoxia under light conditions during fumigation effectively suppressed the phytotoxic effects of PH3 in A. thaliana by increasing the expression of hypoxia-adaptive genes. Moreover, the phytotoxicity of PH3 was also confirmed in pumpkin (Cucurbita moschata Duch.), and was dependent on light. Overall, our findings showed that fumigation under light conditions and ethylene pretreatment could be used to minimize PH3-induced phytotoxic effects in plants.
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Affiliation(s)
- Kyeongnam Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chaeeun Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jinsung Yoo
- Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - Jun-Ran Kim
- Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - Yoon-Ha Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Sung-Eun Lee
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea.
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Angerhausen D, Ottiger M, Dannert F, Miguel Y, Sousa-Silva C, Kammerer J, Menti F, Alei E, Konrad BS, Wang HS, Quanz SP. Large Interferometer for Exoplanets: VIII. Where Is the Phosphine? Observing Exoplanetary PH 3 with a Space-Based Mid-Infrared Nulling Interferometer. ASTROBIOLOGY 2023; 23:183-194. [PMID: 36576793 DOI: 10.1089/ast.2022.0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Phosphine could be a key molecule in the understanding of exotic chemistry that occurs in (exo)planetary atmospheres. While phosphine has been detected in the Solar System's giant planets, it has not been observed in exoplanets to date. In the exoplanetary context, however, it has been theorized to be a potential biosignature molecule. The goal of our study was to identify which illustrative science cases for PH3 chemistry are observable with a space-based mid-infrared nulling interferometric observatory like the Large Interferometer for Exoplanets (LIFE) concept. We identified a representative set of scenarios for PH3 detections in exoplanetary atmospheres that vary over the whole dynamic range of the LIFE mission. We used chemical kinetics and radiative transfer calculations to produce forward models of these informative, prototypical observational cases for LIFEsim, our observation simulator software for LIFE. In a detailed, yet first order approximation, it takes a mission like LIFE: (i) about 1 h to find phosphine in a warm giant around a G star at 10 pc, (ii) about 10 h in H2 or CO2 dominated temperate super-Earths around M star hosts at 5 pc, (iii) and even in 100 h it seems very unlikely that phosphine would be detectable in a Venus-Twin with extreme PH3 concentrations at 5 pc. Phosphine in concentrations previously discussed in the literature is detectable in 2 out of the 3 cases, and it is detected about an order of magnitude faster than in comparable cases with James Webb Space Telescope. We show that there is a significant number of objects accessible for these classes of observations. These results will be used to prioritize the parameter range for the next steps with more detailed retrieval simulations. They will also inform timely questions in the early design phase of a mission like LIFE and guide the community by providing easy-to-scale first estimates for a large part of detection space of such a mission.
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Affiliation(s)
- Daniel Angerhausen
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
- National Center of Competence in Research PlanetS, Bern, Switzerland
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Maurice Ottiger
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
| | - Felix Dannert
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
| | - Yamila Miguel
- SRON Netherlands Institute for Space Research, Utrecht, The Netherlands
- Leiden Observatory, University of Leiden, Leiden, The Netherlands
| | - Clara Sousa-Silva
- Center for Astrophysics, Harvard-Smithsonian, Cambridge, Massachusetts, USA
- Division of Science, Mathematics, and Computing, Bard College, Annandale-on-Hudson, New York, USA
| | - Jens Kammerer
- Space Telescope Science Institute, Baltimore, Maryland, USA
| | - Franziska Menti
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
| | - Eleonora Alei
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
- National Center of Competence in Research PlanetS, Bern, Switzerland
| | - Björn S Konrad
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
- National Center of Competence in Research PlanetS, Bern, Switzerland
| | - Haiyang S Wang
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
- National Center of Competence in Research PlanetS, Bern, Switzerland
| | - Sascha P Quanz
- Department of Physics, Institute for Particle Physics and Astrophysics, ETH Zurich, Zurich, Switzerland
- National Center of Competence in Research PlanetS, Bern, Switzerland
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McKay CP, Davies PCW, Worden SP. Directed Panspermia Using Interstellar Comets. ASTROBIOLOGY 2022; 22:1443-1451. [PMID: 36475964 DOI: 10.1089/ast.2021.0188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
It may be that habitable planets are common but life is rare. If future advances in telescopes increasingly suggest this is so, humankind might feel motivated to seed lifeless planets with resilient terrestrial organisms or synthetic forms designed to thrive on the target planet. A useful mechanism for achieving this goal at a relatively low cost is to use interstellar comets transiting the Solar System to convey microbial cargoes toward nearby planetary systems, where they could disseminate the inoculum via their dust trails. Conversely, it is conceivable that terrestrial life was deliberately seeded in this matter, a hypothesis that could be tested if we found evidence for life on other Solar System bodies that displayed common basic biochemical signatures. Our scenario raises a number of ethical and technological challenges that need to be addressed.
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Affiliation(s)
- Christopher P McKay
- Space Science Division, NASA Ames Research Center, Moffett Field, California, USA
| | - Paul C W Davies
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona, USA
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35
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Somayaji A, Dhanjal CR, Lingamsetty R, Vinayagam R, Selvaraj R, Varadavenkatesan T, Govarthanan M. An insight into the mechanisms of homeostasis in extremophiles. Microbiol Res 2022; 263:127115. [PMID: 35868258 DOI: 10.1016/j.micres.2022.127115] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 07/07/2022] [Accepted: 07/07/2022] [Indexed: 01/10/2023]
Abstract
The homeostasis of extremophiles is one that is a diamond hidden in the rough. The way extremophiles adapt to their extreme environments gives a clue into the true extent of what is possible when it comes to life. The discovery of new extremophiles is ever-expanding and an explosion of knowledge surrounding their successful existence in extreme environments is obviously perceived in scientific literature. The present review paper aims to provide a comprehensive view on the different mechanisms governing the extreme adaptations of extremophiles, along with insights and discussions on what the limits of life can possibly be. The membrane adaptations that are vital for survival are discussed in detail. It was found that there are many alterations in the genetic makeup of such extremophiles when compared to their mesophilic counterparts. Apart from the several proteins involved, the significance of chaperones, efflux systems, DNA repair proteins and a host of other enzymes that adapt to maintain functionality, are enlisted, and explained. A deeper understanding of the underlying mechanisms could have a plethora of applications in the industry. There are cases when certain microbes can withstand extreme doses of antibiotics. Such microbes accumulate numerous genetic elements (or plasmids) that possess genes for multiple drug resistance (MDR). A deeper understanding of such mechanisms helps in the development of potential approaches and therapeutic schemes for treating pathogen-mediated outbreaks. An in-depth analysis of the parameters - radiation, pressure, temperature, pH value and metal resistance - are discussed in this review, and the key to survival in these precarious niches is described.
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Affiliation(s)
- Adithi Somayaji
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India; Manipal Biomachines, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Chetan Roger Dhanjal
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India; Manipal Biomachines, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Rathnamegha Lingamsetty
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India; Manipal Biomachines, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Ramesh Vinayagam
- Department of Chemical Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Raja Selvaraj
- Department of Chemical Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Thivaharan Varadavenkatesan
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - Muthusamy Govarthanan
- Department of Environmental Engineering, Kyungpook National University, Daegu, South Korea; Department of Biomaterials, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai 600077, India.
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36
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Malaterre C, Jeancolas C, Nghe P. The Origin of Life: What Is the Question? ASTROBIOLOGY 2022; 22:851-862. [PMID: 35594335 PMCID: PMC9298494 DOI: 10.1089/ast.2021.0162] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/12/2022] [Indexed: 06/15/2023]
Abstract
The question of the origin of life is a tenacious question that challenges many branches of science but is also extremely multifaceted. While prebiotic chemistry and micropaleontology reformulate the question as that of explaining the appearance of life on Earth in the deep past, systems chemistry and synthetic biology typically understand the question as that of demonstrating the synthesis of novel living matter from nonliving matter independently of historical constraints. The objective of this contribution is to disentangle the different readings of the origin-of-life question found in science. We identify three main dimensions along which the question can be differently constrained depending on context: historical adequacy, natural spontaneity, and similarity to life-as-we-know-it. We argue that the epistemic status of what needs to be explained-the explanandum-varies from approximately true when the origin-of-life question is the most constrained to entirely speculative when the constraints are the most relaxed. This difference in epistemic status triggers a shift in the nature of the origin-of-life question from an explanation-seeking question in the most constrained case to a fact-establishing question in the lesser-constrained ones. We furthermore explore how answers to some interpretations of the origin-of-life questions matter for other interpretations.
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Affiliation(s)
- Christophe Malaterre
- Département de philosophie, Université du Québec à Montréal (UQAM), Montréal, Canada
- Centre interuniversitaire de recherche sur la science et la technologie (CIRST), Université du Québec à Montréal (UQAM), Montréal, Canada
| | - Cyrille Jeancolas
- Laboratoire Biophysique et Évolution, UMR Chimie Biologie Innovation 8231, ESPCI Paris, Université PSL, CNRS, Paris, France
- Laboratoire d'Anthropologie Sociale, Collège de France, Paris, France
| | - Philippe Nghe
- Laboratoire Biophysique et Évolution, UMR Chimie Biologie Innovation 8231, ESPCI Paris, Université PSL, CNRS, Paris, France
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37
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Journaux B. Salty ice and the dilemma of ocean exoplanet habitability. Nat Commun 2022; 13:3304. [PMID: 35729159 PMCID: PMC9213393 DOI: 10.1038/s41467-022-30799-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/06/2022] [Indexed: 11/09/2022] Open
Affiliation(s)
- Baptiste Journaux
- Earth and Space Science Department, University of Washington, Seattle, WA, USA.
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38
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Hernández G. Schrödinger and the Possible Existence of Different Types of Life. Front Microbiol 2022; 13:902212. [PMID: 35711773 PMCID: PMC9194607 DOI: 10.3389/fmicb.2022.902212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
Eighty years ago, Nobel Prize-winner physicist Erwin Schrödinger gave three lectures in Dublin’s Trinity College, titled What is Life? The physical aspect of the living cell to explain life in terms of the chemistry and physics laws. Life definitions rely on the cellular theory, which poses in the first place that life is made up of cells. The recent discovery of giant viruses, along with the development of synthetic cells at the beginning of century 21st, has challenged the current idea of what life is. Thus, rather than having arrived at a close answer to Schrödinger’s question, modern biology has touched down at a novel scenario in which several types of life—as opposed to only one—actually might exist on Earth and possibly the Universe. Eighty years after the Dublin lectures, the Schrödinger question could be: “What are lives”?
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Affiliation(s)
- Greco Hernández
- Translation and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (Instituto Nacional de Cancerología, INCan), Mexico City, Mexico
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39
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Sephus CD, Fer E, Garcia AK, Adam ZR, Schwieterman EW, Kaçar B. Earliest photic zone niches probed by ancestral microbial rhodopsins. Mol Biol Evol 2022; 39:6582242. [PMID: 35524714 PMCID: PMC9117797 DOI: 10.1093/molbev/msac100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
For billions of years, life has continuously adapted to dynamic physical conditions near the Earth’s surface. Fossils and other preserved biosignatures in the paleontological record are the most direct evidence for reconstructing the broad historical contours of this adaptive interplay. However, biosignatures dating to Earth’s earliest history are exceedingly rare. Here, we combine phylogenetic inference of primordial rhodopsin proteins with modeled spectral features of the Precambrian Earth environment to reconstruct the paleobiological history of this essential family of photoactive transmembrane proteins. Our results suggest that ancestral microbial rhodopsins likely acted as light-driven proton pumps and were spectrally tuned toward the absorption of green light, which would have enabled their hosts to occupy depths in a water column or biofilm where UV wavelengths were attenuated. Subsequent diversification of rhodopsin functions and peak absorption frequencies was enabled by the expansion of surface ecological niches induced by the accumulation of atmospheric oxygen. Inferred ancestors retain distinct associations between extant functions and peak absorption frequencies. Our findings suggest that novel information encoded by biomolecules can be used as “paleosensors” for conditions of ancient, inhabited niches of host organisms not represented elsewhere in the paleontological record. The coupling of functional diversification and spectral tuning of this taxonomically diverse protein family underscores the utility of rhodopsins as universal testbeds for inferring remotely detectable biosignatures on inhabited planetary bodies.
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Affiliation(s)
- Cathryn D Sephus
- NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI, USA
| | - Evrim Fer
- NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI, USA.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.,Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Amanda K Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Zachary R Adam
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA.,Blue Marble Space Institute of Science, Seattle, WA, USA
| | - Edward W Schwieterman
- Blue Marble Space Institute of Science, Seattle, WA, USA.,Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA
| | - Betül Kaçar
- NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI, USA.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
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40
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Thompson MA, Krissansen-Totton J, Wogan N, Telus M, Fortney JJ. The case and context for atmospheric methane as an exoplanet biosignature. Proc Natl Acad Sci U S A 2022; 119:e2117933119. [PMID: 35353627 PMCID: PMC9168929 DOI: 10.1073/pnas.2117933119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/31/2022] [Indexed: 11/24/2022] Open
Abstract
Methane has been proposed as an exoplanet biosignature. Imminent observations with the James Webb Space Telescope may enable methane detections on potentially habitable exoplanets, so it is essential to assess in what planetary contexts methane is a compelling biosignature. Methane’s short photochemical lifetime in terrestrial planet atmospheres implies that abundant methane requires large replenishment fluxes. While methane can be produced by a variety of abiotic mechanisms such as outgassing, serpentinizing reactions, and impacts, we argue that—in contrast to an Earth-like biosphere—known abiotic processes cannot easily generate atmospheres rich in CH4 and CO2 with limited CO due to the strong redox disequilibrium between CH4 and CO2. Methane is thus more likely to be biogenic for planets with 1) a terrestrial bulk density, high mean-molecular-weight and anoxic atmosphere, and an old host star; 2) an abundance of CH4 that implies surface fluxes exceeding what could be supplied by abiotic processes; and 3) atmospheric CO2 with comparatively little CO.
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Affiliation(s)
- Maggie A. Thompson
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064
| | | | - Nicholas Wogan
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195
| | - Myriam Telus
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064
| | - Jonathan J. Fortney
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064
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41
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From Atmospheric Evolution to the Search of Species of Astrobiological Interest in the Solar System—Case Studies Using the Planetary Spectrum Generator. ATMOSPHERE 2022. [DOI: 10.3390/atmos13030461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The study of minor chemical species in terrestrial planets’ atmospheres can teach us about the chemistry, dynamics and evolution of the atmospheres through time. Phosphine or methane on terrestrial planets are potential biosignatures, such that their detection may signify the presence of life on a planet. Therefore, the search for these species in the solar system is an important step for the subsequent application of the same techniques to exoplanetary atmospheres. To study atmospheric depletion and the evolution of water abundance in the atmospheres of terrestrial planets, the estimation of the D/H ratio and its spatial and temporal variability is used. We used the Planetary Spectrum Generator (PSG), a radiative transfer suite, with the goal of simulating spectra from observations of Venus, Mars and Jupiter, searching for minor chemical species. The present study contributes to highlight that the PSG is an efficient tool for studying minor chemical species and compounds of astrobiological interest in planetary atmospheres, allowing to perform the detection and retrieval of the relevant molecular species. Regarding detection, it is effective in disentangling different molecular opacities affecting observations. In order to contribute to the scientific community that is focused on the study of minor chemical species in the solar system’s atmospheres, using this tool, in this work, we present the results from an analysis of observations of Venus, Mars and Jupiter, by comparison of observations with simulations in the infrared (IR). The first step was to clearly identify the position of molecular features using our model simulations, since the molecular absorption/emission features of different molecules tend to overlap. For this step, we used the method of the variation of abundances. The second step was to determine the molecular abundances and compare them with values from the literature using the retrieval method and the line depth ratio method. For Venus, our study of SO2-related observations by the Texas Echelon Cross Echelle Spectrograph (TEXES) at 7.4 μm enabled the identification of absorption lines due to sulphur dioxide and carbon dioxide as well as constrain the abundance of SO2 at the cloud top. Phosphine was not detected in the comparison between the simulation and TEXES IR observations around 10.5 μm. For Mars, both a positive and a non-detection of methane were studied using PSG simulations. The related spectra observations in the IR, at approximately 3.3 μm, correspond, respectively, to the Mars Express (MEx) and ExoMars space probes. Moreover, an estimate of the deuterium-to-hydrogen ratio (D/H ratio) was obtained by comparing the simulations with observations by the Echelon Cross Echelle Spectrograph (EXES) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) at approximately 7.19–7.23 μm. For Jupiter, the detection of ammonia, phosphine, deuterated methane and methane was studied, by comparing the simulations with IR observations by the Infrared Space Observatory (ISO) at approximately 7–12 μm. Moreover, the retrieval of the profiles of ammonia and phosphine was performed.
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42
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Medina-Chávez NO, Travisano M. Archaeal Communities: The Microbial Phylogenomic Frontier. Front Genet 2022; 12:693193. [PMID: 35154237 PMCID: PMC8826477 DOI: 10.3389/fgene.2021.693193] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 11/22/2021] [Indexed: 11/17/2022] Open
Abstract
Archaea are a unique system for investigating the diversity of life. There are the most diverse group of organisms with the longest evolutionary history of life on Earth. Phylogenomic investigations reveal the complex evolutionary history of Archaea, overturning longstanding views of the history of life. They exist in the harshest environments and benign conditions, providing a system to investigate the basis for living in extreme environments. They are frequently members of microbial communities, albeit generally rare. Archaea were central in the evolution of Eukaryotes and can be used as a proxy for studying life on other planets. Future advances will depend not only upon phylogenomic studies but also on a better understanding of isolation and cultivation techniques.
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Affiliation(s)
- Nahui Olin Medina-Chávez
- Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, United States.,BioTechnology Institute, University of Minnesota, St. Paul, MN, United States
| | - Michael Travisano
- Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, United States.,BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.,Minnesota Center for the Philosophy of Science, University of Minnesota, Minneapolis, MN, United States
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43
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Lisak D, Charczun D, Nishiyama A, Voumard T, Wildi T, Kowzan G, Brasch V, Herr T, Fleisher AJ, Hodges JT, Ciuryło R, Cygan A, Masłowski P. Dual-comb cavity ring-down spectroscopy. Sci Rep 2022; 12:2377. [PMID: 35149716 PMCID: PMC8837621 DOI: 10.1038/s41598-022-05926-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/12/2022] [Indexed: 12/16/2022] Open
Abstract
Cavity ring-down spectroscopy is a ubiquitous optical method used to study light-matter interactions with high resolution, sensitivity and accuracy. However, it has never been performed with the multiplexing advantages of direct frequency comb spectroscopy without significantly compromising spectral resolution. We present dual-comb cavity ring-down spectroscopy (DC-CRDS) based on the parallel heterodyne detection of ring-down signals with a local oscillator comb to yield absorption and dispersion spectra. These spectra are obtained from widths and positions of cavity modes. We present two approaches which leverage the dynamic cavity response to coherently or randomly driven changes in the amplitude or frequency of the probe field. Both techniques yield accurate spectra of methane-an important greenhouse gas and breath biomarker. When combined with broadband frequency combs, the high sensitivity, spectral resolution and accuracy of our DC-CRDS technique shows promise for applications like studies of the structure and dynamics of large molecules, multispecies trace gas detection and isotopic composition.
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Affiliation(s)
- Daniel Lisak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland.
| | - Dominik Charczun
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
| | - Akiko Nishiyama
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8563, Japan
| | - Thibault Voumard
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Thibault Wildi
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Grzegorz Kowzan
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
| | - Victor Brasch
- CSEM - Swiss Center for Electronics and Microtechnology, 2000, Neuchâtel, Switzerland
| | - Tobias Herr
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
- Physics Department, Universität Hamburg UHH, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Adam J Fleisher
- Optical Measurements Group, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Joseph T Hodges
- Optical Measurements Group, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Roman Ciuryło
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
| | - Agata Cygan
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
| | - Piotr Masłowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland
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44
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Messmer MW, Dieser M, Smith HJ, Parker AE, Foreman CM. Investigation of Raman Spectroscopic Signatures with Multivariate Statistics: An Approach for Cataloguing Microbial Biosignatures. ASTROBIOLOGY 2022; 22:14-24. [PMID: 34558961 DOI: 10.1089/ast.2021.0021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spectroscopic instruments are increasingly being implemented in the search for extraterrestrial life. However, microstructural spectral analyses of alien environments could prove difficult without knowledge on the molecular identification of individual spectral signatures. To bridge this gap, we introduce unsupervised K-means clustering as a statistical approach to discern spectral patterns of biosignatures without prior knowledge of spectral regions of biomolecules. Spectral profiles of bacterial isolates from analogous polar ice sheets were measured with Raman spectroscopy. Raman analysis identified carotenoid and violacein pigments, and key cellular features including saturated and unsaturated fats, triacylglycerols, and proteins. Principal component analysis and targeted spectra integration biplot analysis revealed that the clustering of bacterial isolates was attributed to spectral biosignatures influenced by carotenoid pigments and ratio of unsaturated/saturated fat peaks. Unsupervised K-means clustering highlighted the prevalence of the corresponding spectral peaks, while subsequent supervised permutational multivariate analysis of variance provided statistical validation for spectral differences associated with the identified cellular features. Establishing a validated catalog of spectral signatures of analogous biotic and abiotic materials, in combination with targeted supervised tools, could prove effective at identifying extant biosignatures.
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Affiliation(s)
- Mitch W Messmer
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemical & Biological Engineering, Montana State University, Bozeman, Montana, USA
| | - Markus Dieser
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemical & Biological Engineering, Montana State University, Bozeman, Montana, USA
| | - Heidi J Smith
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Microbiology and Cell Biology, and Montana State University, Bozeman, Montana, USA
| | - Albert E Parker
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Mathematical Sciences, Montana State University, Bozeman, Montana, USA
| | - Christine M Foreman
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemical & Biological Engineering, Montana State University, Bozeman, Montana, USA
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45
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Bains W, Petkowski JJ, Seager S, Ranjan S, Sousa-Silva C, Rimmer PB, Zhan Z, Greaves JS, Richards AMS. Phosphine on Venus Cannot Be Explained by Conventional Processes. ASTROBIOLOGY 2021; 21:1277-1304. [PMID: 34283644 DOI: 10.1089/ast.2020.2352] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The recent candidate detection of ∼1 ppb of phosphine in the middle atmosphere of Venus is so unexpected that it requires an exhaustive search for explanations of its origin. Phosphorus-containing species have not been modeled for Venus' atmosphere before, and our work represents the first attempt to model phosphorus species in the venusian atmosphere. We thoroughly explore the potential pathways of formation of phosphine in a venusian environment, including in the planet's atmosphere, cloud and haze layers, surface, and subsurface. We investigate gas reactions, geochemical reactions, photochemistry, and other nonequilibrium processes. None of these potential phosphine production pathways is sufficient to explain the presence of ppb phosphine levels on Venus. If PH3's presence in Venus' atmosphere is confirmed, it therefore is highly likely to be the result of a process not previously considered plausible for venusian conditions. The process could be unknown geochemistry, photochemistry, or even aerial microbial life, given that on Earth phosphine is exclusively associated with anthropogenic and biological sources. The detection of phosphine adds to the complexity of chemical processes in the venusian environment and motivates in situ follow-up sampling missions to Venus. Our analysis provides a template for investigation of phosphine as a biosignature on other worlds.
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Affiliation(s)
- William Bains
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Janusz J Petkowski
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sara Seager
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sukrit Ranjan
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Clara Sousa-Silva
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Paul B Rimmer
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Zhuchang Zhan
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jane S Greaves
- School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Anita M S Richards
- Department of Physics and Astronomy, Jodrell Bank Centre for Astrophysics, The University of Manchester, Manchester, United Kingdom
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46
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Omran A, Oze C, Jackson B, Mehta C, Barge LM, Bada J, Pasek MA. Phosphine Generation Pathways on Rocky Planets. ASTROBIOLOGY 2021; 21:1264-1276. [PMID: 34551269 DOI: 10.1089/ast.2021.0034] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The possibility of life in the venusian clouds was proposed in the 1960s, and recently this hypothesis has been revived with the potential detection of phosphine (PH3) in Venus' atmosphere. These observations may have detected ∼5-20 ppb phosphine on Venus (Greaves et al., 2020), which raises questions about venusian atmospheric/geochemical processes and suggests that this phosphine could possibly be generated by biological processes. In such a claim, it is essential to understand the abiotic phosphorus chemistry that may occur under Venus-relevant conditions, particularly those processes that may result in phosphine generation. Here, we discuss two related abiotic routes for phosphine generation within the atmosphere of Venus. Based on our assessment, corrosion of large impactors as they ablate near Venus' cloud layer, and the presence of reduced phosphorus compounds in the subcloud layer could result in production of phosphine and may explain the phosphine detected in Venus' atmosphere or on other rocky planets. We end on a cautionary note: although there may be life in the clouds of Venus, the detection of a simple, single gas, phosphine, is likely not a decisive indicator.
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Affiliation(s)
- Arthur Omran
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
| | - Christopher Oze
- Geology Department, Occidental College, Los Angeles, California, USA
| | - Brian Jackson
- Department of Physics, Boise State University, Boise, Idaho, USA
| | - Chris Mehta
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
| | - Laura M Barge
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jeffrey Bada
- Scripps Institution of Oceanography Department, University of California at San Diego, La Jolla, California, USA
| | - Matthew A Pasek
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
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47
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Quanz SP, Absil O, Benz W, Bonfils X, Berger JP, Defrère D, van Dishoeck E, Ehrenreich D, Fortney J, Glauser A, Grenfell JL, Janson M, Kraus S, Krause O, Labadie L, Lacour S, Line M, Linz H, Loicq J, Miguel Y, Pallé E, Queloz D, Rauer H, Ribas I, Rugheimer S, Selsis F, Snellen I, Sozzetti A, Stapelfeldt KR, Udry S, Wyatt M. Atmospheric characterization of terrestrial exoplanets in the mid-infrared: biosignatures, habitability, and diversity. EXPERIMENTAL ASTRONOMY 2021; 54:1197-1221. [PMID: 36915622 PMCID: PMC9998579 DOI: 10.1007/s10686-021-09791-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
Exoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for signatures in their atmospheres that indicate biological activity, assess their ability to provide conditions for life as we know it, and investigate their expected atmospheric diversity. None of the currently adopted projects or missions, from ground or in space, can address these goals. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we argue that a large space-based mission designed to detect and investigate thermal emission spectra of terrestrial exoplanets in the mid-infrared wavelength range provides unique scientific potential to address these goals and surpasses the capabilities of other approaches. While NASA might be focusing on large missions that aim to detect terrestrial planets in reflected light, ESA has the opportunity to take leadership and spearhead the development of a large mid-infrared exoplanet mission within the scope of the "Voyage 2050" long-term plan establishing Europe at the forefront of exoplanet science for decades to come. Given the ambitious science goals of such a mission, additional international partners might be interested in participating and contributing to a roadmap that, in the long run, leads to a successful implementation. A new, dedicated development program funded by ESA to help reduce development and implementation cost and further push some of the required key technologies would be a first important step in this direction. Ultimately, a large mid-infrared exoplanet imaging mission will be needed to help answer one of humankind's most fundamental questions: "How unique is our Earth?"
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Affiliation(s)
- Sascha P. Quanz
- ETH Zurich, Institute for Particle Physics and Astrophysics, Zurich, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | | - Oliver Krause
- Max Planck Institute for Astronomy, Heidelberg, Germany
| | | | | | | | - Hendrik Linz
- Max Planck Institute for Astronomy, Heidelberg, Germany
| | - Jérôme Loicq
- Faculty of Aerospace Engineering, Delft University of Technology, Delft, Netherlands
| | | | - Enric Pallé
- Instituto de Astrofisica de Canarias, Santa Cruz de Tenerife, Spain
| | | | - Heike Rauer
- German Aerospace Center (DLR), Berlin, Germany
| | - Ignasi Ribas
- Institut de Ciencies de l’Espai, Barcelona, Spain
| | | | - Franck Selsis
- Laboratoire d’astrophysique de Bordeaux, Bordeaux, France
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48
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Komatsu Y, Takizawa K. A quantum chemical study on the effects of varying the central metal in extended photosynthetic pigments. Phys Chem Chem Phys 2021; 23:14404-14414. [PMID: 34180470 DOI: 10.1039/d1cp00760b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In a certain period of Earth's history, chlorophylls with Mg as their central metal would have been selected as the major photosynthetic pigments, reflecting the radiation in habitats. Assuming evolution in different light and material environments, different photosynthetic pigments would occur. This study is the first attempt to evaluate the physical and chemical properties of model photosynthetic pigments and their potential to function in a variety of light environments using quantum chemistry calculations. Specifically, bacteriochlorophyll b (Bchl b), phthalocyanine (Pht) and meso-dibenzoporphycene (mDBPc) were selected as template molecules, while Be, Mg, Ca, Ni, Zn, Sr, Pd, Cd, Ba, Pt, Hg, Pb and H2 were examined as the central metals in each molecule in various solvents. The results showed that the light absorption by each of these compounds varied over a range of 100 nm depending on the central metal and the surrounding solvent, and Pb produced the largest red shift in the absorption bands of all three photosynthetic pigments. The Pht molecules showed similar redox properties to the chlorophylls, suggesting that these derivatives could be substituted for the special pairs in reaction centers, while the mDBPc molecules appear to be more suitable as accessory pigments due to their extraordinarily broad absorption ranges of approximately 500 nm depending on the conditions.
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Affiliation(s)
- Yu Komatsu
- AstroBiology Center, Osawa 2-21-1, Mitaka, Tokyo, Japan. and National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo, Japan
| | - Kenji Takizawa
- AstroBiology Center, Osawa 2-21-1, Mitaka, Tokyo, Japan. and National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi, Japan
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49
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Lyons TW, Diamond CW, Planavsky NJ, Reinhard CT, Li C. Oxygenation, Life, and the Planetary System during Earth's Middle History: An Overview. ASTROBIOLOGY 2021; 21:906-923. [PMID: 34314605 PMCID: PMC8403206 DOI: 10.1089/ast.2020.2418] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The long history of life on Earth has unfolded as a cause-and-effect relationship with the evolving amount of oxygen (O2) in the oceans and atmosphere. Oxygen deficiency characterized our planet's first 2 billion years, yet evidence for biological O2 production and local enrichments in the surface ocean appear long before the first accumulations of O2 in the atmosphere roughly 2.4 to 2.3 billion years ago. Much has been written about this fundamental transition and the related balance between biological O2 production and sinks coupled to deep Earth processes that could buffer against the accumulation of biogenic O2. However, the relationship between complex life (eukaryotes, including animals) and later oxygenation is less clear. Some data suggest O2 was higher but still mostly low for another billion and a half years before increasing again around 800 million years ago, potentially setting a challenging course for complex life during its initial development and ecological expansion. The apparent rise in O2 around 800 million years ago is coincident with major developments in complex life. Multiple geochemical and paleontological records point to a major biogeochemical transition at that time, but whether rising and still dynamic biospheric oxygen triggered or merely followed from innovations in eukaryotic ecology, including the emergence of animals, is still debated. This paper focuses on the geochemical records of Earth's middle history, roughly 1.8 to 0.5 billion years ago, as a backdrop for exploring possible cause-and-effect relationships with biological evolution and the primary controls that may have set its pace, including solid Earth/tectonic processes, nutrient limitation, and their possible linkages. A richer mechanistic understanding of the interplay between coevolving life and Earth surface environments can provide a template for understanding and remotely searching for sustained habitability and even life on distant exoplanets.
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Affiliation(s)
- Timothy W. Lyons
- Department of Earth and Planetary Sciences, University of California, Riverside, California, USA
- Address correspondence to: Timothy W. Lyons, Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA
| | - Charles W. Diamond
- Department of Earth and Planetary Sciences, University of California, Riverside, California, USA
| | - Noah J. Planavsky
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Christopher T. Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Chao Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
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50
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Rivera-Valentín EG, Filiberto J, Lynch KL, Mamajanov I, Lyons TW, Schulte M, Méndez A. Introduction-First Billion Years: Habitability. ASTROBIOLOGY 2021; 21:893-905. [PMID: 34406807 PMCID: PMC8403211 DOI: 10.1089/ast.2020.2314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 12/22/2020] [Indexed: 06/13/2023]
Abstract
The physical processes active during the first billion years (FBY) of Earth's history, such as accretion, differentiation, and impact cratering, provide constraints on the initial conditions that were conducive to the formation and establishment of life on Earth. This motivated the Lunar and Planetary Institute's FBY topical initiative, which was a four-part conference series intended to look at each of these physical processes to study the basic structure and composition of our Solar System that was set during the FBY. The FBY Habitability conference, held in September 2019, was the last in this series and was intended to synthesize the initiative; specifically, to further our understanding of the origins of life, planetary and environmental habitability, and the search for life beyond Earth. The conference included discussions of planetary habitability and the potential emergence of life on bodies within our Solar System, as well as extrasolar systems by applying our knowledge of the Solar System's FBY, and in particular Earth's early history. To introduce this Special Collection, which resulted from work discussed at the conference, we provide a review of the main themes and a synopsis of the FBY Habitability conference.
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Affiliation(s)
| | - Justin Filiberto
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Kennda L. Lynch
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Irena Mamajanov
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Timothy W. Lyons
- Department of Earth and Planetary Sciences, University of California Riverside, Riverside, California, USA
| | - Mitch Schulte
- Planetary Science Division, NASA Headquarters, Washington, District of Columbia, USA
| | - Abel Méndez
- Planetary Habitability Laboratory, University of Puerto Rico Arecibo, Arecibo, Puerto Rico
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