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McMahon S, Parnell J, Reekie PBR. Mars-Analog Calcium Sulfate Veins Record Evidence of Ancient Subsurface Life. ASTROBIOLOGY 2020; 20:1212-1223. [PMID: 32985907 DOI: 10.1089/ast.2019.2172] [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: 06/11/2023]
Abstract
Ancient veins of calcium sulfate minerals (anhydrite, bassanite, and gypsum) deposited by subsurface aqueous fluids crosscut fluviolacustrine sedimentary rocks at multiple localities on Mars. Although these veins have been considered an attractive target for astrobiological investigation, their potential to preserve biosignatures is poorly understood. Here, we report the presence of biogenic authigenic pyrite in a fibrous gypsum vein of probable Cenozoic emplacement age from Permian lacustrine rocks in Northwest England. Pyrite occurs at the vein margins and displays a complex interfingering boundary with the surrounding gypsum suggestive of replacive authigenic growth. Gypsum-entombed carbonaceous material of probable organic origin was also identified by Raman spectroscopic microscopy in close proximity to the pyrite. Spatially resolved ion microprobe (SIMS) measurements reveal that the pyrite sulfur isotope composition is consistently very light (δ34SVCDT = -30.7‰). Comparison with the sulfate in the vein gypsum (δ34SVCDT = +8.5‰) indicates a fractionation too large to be explained by nonbiological (thermochemical) sulfate reduction. We infer that the pyrite was precipitated by microorganisms coupling the reduction of vein-derived sulfate with the oxidation of wall-derived organic matter. This is the first evidence that such veins can incorporate biosignatures that remain stable over geological time, which could be detected in samples returned from Mars.
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Affiliation(s)
- S McMahon
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- School of Geosciences, Grant Institute, University of Edinburgh, Edinburgh, UK
| | - J Parnell
- School of Geosciences, University of Aberdeen, King's College, Aberdeen, UK
| | - P B R Reekie
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- School of Geosciences, Grant Institute, University of Edinburgh, Edinburgh, UK
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52
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Schaefer K, Dambuza IM, Dall’Angelo S, Yuecel R, Jaspars M, Trembleau L, Zanda M, Brown GD, Netea MG, Gow NAR. A Weakened Immune Response to Synthetic Exo-Peptides Predicts a Potential Biosecurity Risk in the Retrieval of Exo-Microorganisms. Microorganisms 2020; 8:microorganisms8071066. [PMID: 32708909 PMCID: PMC7409182 DOI: 10.3390/microorganisms8071066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/30/2020] [Accepted: 07/15/2020] [Indexed: 11/25/2022] Open
Abstract
Simple Summary We tested the immune response of T cells of the mammalian immune system towards protein antigens that includes the unusual amino acids isovaline and α-aminoisobutyric. Those amino acids have been found in high abundance on carbonaceous meteorites but are extremely rare in proteomes of earth organisms. We hypothesised that proteins of non-terrestrial alien life forms might contain such amino acids and tested whether chemically synthesised “exopeptides” that contain these amino acids could be detected by the immune system. Our assays, based on the responses of CD8+ T cells to these exopeptides, indicated that antigen cleavage, processing, and subsequent T cell activation still occurred, but were less efficient than the response to control peptides that lacked these amino acids. We therefore speculate that the encounter of putative exo-microorganisms of an unusual antigenic repertoire might pose an immunological risk for space missions aiming to retrieve potentially biotic samples from exoplanets and moons. Abstract The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth’s ecosystem. Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites. It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids. We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides. This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.
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Affiliation(s)
- Katja Schaefer
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (I.M.D.); (G.D.B.); (N.A.R.G.)
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
- Correspondence:
| | - Ivy M. Dambuza
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (I.M.D.); (G.D.B.); (N.A.R.G.)
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - Sergio Dall’Angelo
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK; (S.D.); (M.Z.)
| | - Raif Yuecel
- Iain Fraser Cytometry Centre (IFCC), University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK;
- Centre for Cytomics, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Marcel Jaspars
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, UK; (M.J.); (L.T.)
| | - Laurent Trembleau
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, UK; (M.J.); (L.T.)
| | - Matteo Zanda
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK; (S.D.); (M.Z.)
- Sir David Davies Building, Centre for Imaging Science, School of Science, Loughborough University, Loughborough LE11 3TU, UK
| | - Gordon D. Brown
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (I.M.D.); (G.D.B.); (N.A.R.G.)
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - Mihai G. Netea
- Department of Internal Medicine, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
- Department for Genomics & Immunoregulation, Life and Medical Sciences Institute (LIMES), University of Bonn, 53115 Bonn, Germany
| | - Neil A. R. Gow
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (I.M.D.); (G.D.B.); (N.A.R.G.)
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
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53
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Broz AP. Organic Matter Preservation in Ancient Soils of Earth and Mars. Life (Basel) 2020; 10:E113. [PMID: 32708606 PMCID: PMC7400377 DOI: 10.3390/life10070113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/28/2020] [Accepted: 07/11/2020] [Indexed: 11/21/2022] Open
Abstract
The emerging field of astropedology is the study of ancient soils on Earth and other planetary bodies. Examination of the complex factors that control the preservation of organic matter and other biosignatures in ancient soils is a high priority for current and future missions to Mars. Though previously defined by biological activity, an updated definition of soil as planetary surfaces altered in place by biological, chemical or physical processes was adopted in 2017 by the Soil Science Society of America in response to mounting evidence of pedogenic-like features on Mars. Ancient (4.1-3.7 billion year old [Byr]) phyllosilicate-rich surface environments on Mars show evidence of sustained subaerial weathering of sediments with liquid water at circumneutral pH, which is a soil-forming process. The accumulation of buried, fossilized soils, or paleosols, has been widely observed on Earth, and recent investigations suggest paleosol-like features may be widespread across the surface of Mars. However, the complex array of preservation and degradation factors controlling the fate of biosignatures in paleosols remains unexplored. This paper identifies the dominant factors contributing to the preservation and degradation of organic carbon in paleosols through the geological record on Earth, and offers suggestions for prioritizing locations for in situ biosignature detection and Mars Sample Return across a diverse array of potential paleosols and paleoenvironments of early Mars. A compilation of previously published data and original research spanning a diverse suite of paleosols from the Pleistocene (1 Myr) to the Archean (3.7 Byr) show that redox state is the predominant control for the organic matter content of paleosols. Most notably, the chemically reduced surface horizons (layers) of Archean (2.3 Byr) paleosols have organic matter concentrations ranging from 0.014-0.25%. However, clay mineralogy, amorphous phase abundance, diagenetic alteration and sulfur content are all significant factors that influence the preservation of organic carbon. The surface layers of paleosols that formed under chemically reducing conditions with high amounts of iron/magnesium smectites and amorphous colloids should be considered high priority locations for biosignature investigation within subaerial paleoenvironments on Mars.
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Affiliation(s)
- Adrian P Broz
- Department of Earth Sciences, University of Oregon, Eugene, OR 97405, USA
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55
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Newman SA, Lincoln SA, O'Reilly S, Liu X, Shock EL, Kelemen PB, Summons RE. Lipid Biomarker Record of the Serpentinite-Hosted Ecosystem of the Samail Ophiolite, Oman and Implications for the Search for Biosignatures on Mars. ASTROBIOLOGY 2020; 20:830-845. [PMID: 32648829 DOI: 10.1089/ast.2019.2066] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Serpentinization is a weathering process in which ultramafic rocks react with water, generating a range of products, including serpentine and other minerals, in addition to H2 and low-molecular-weight hydrocarbons that are capable of sustaining microbial life. Lipid biomarker analyses of serpentinite-hosted ecosystems hold promise as tools for investigating microbial activity in ancient Earth environments and other terrestrial planets such as Mars because lipids have the potential for longer term preservation relative to DNA, proteins, and other more labile organic molecules. Here, we report the first lipid biomarker record of microbial activity in the mantle section of the Samail Ophiolite, in the Sultanate of Oman, a site undergoing active serpentinization. We detected isoprenoidal (archaeal) and branched (bacterial) glycerol dialkyl glycerol tetraether (GDGT) lipids, including those with 0-3 cyclopentane moieties, and crenarchaeol, an isoprenoidal GDGT containing four cyclopentane and one cyclohexane moieties, as well as monoether lipids and fatty acids indicative of sulfate-reducing bacteria. Comparison of our geochemical data and 16S rRNA data from the Samail Ophiolite with those from other serpentinite-hosted sites identifies the existence of a common core serpentinization microbiome. In light of these findings, we also discuss the preservation potential of serpentinite lipid biomarker assemblages on Earth and Mars. Continuing investigations of the Samail Ophiolite and other terrestrial analogues will enhance our understanding of microbial habitability and diversity in serpentinite-hosted environments on Earth and elsewhere in the Solar System.
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Affiliation(s)
- Sharon A Newman
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - Sara A Lincoln
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Shane O'Reilly
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- School of Earth Sciences, University College Dublin, Belfield, Ireland
| | - Xiaolei Liu
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma
| | - Everett L Shock
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
- Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, Arizona
| | - Peter B Kelemen
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
| | - Roger E Summons
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
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56
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Ligterink NFW, Grimaudo V, Moreno-García P, Lukmanov R, Tulej M, Leya I, Lindner R, Wurz P, Cockell CS, Ehrenfreund P, Riedo A. ORIGIN: a novel and compact Laser Desorption - Mass Spectrometry system for sensitive in situ detection of amino acids on extraterrestrial surfaces. Sci Rep 2020; 10:9641. [PMID: 32541786 PMCID: PMC7296031 DOI: 10.1038/s41598-020-66240-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 05/14/2020] [Indexed: 11/17/2022] Open
Abstract
For the last four decades space exploration missions have searched for molecular life on planetary surfaces beyond Earth. Often pyrolysis gas chromatography mass spectrometry has been used as payload on such space exploration missions. These instruments have relatively low detection sensitivity and their measurements are often undermined by the presence of chloride salts and minerals. Currently, ocean worlds in the outer Solar System, such as the icy moons Europa and Enceladus, represent potentially habitable environments and are therefore prime targets for the search for biosignatures. For future space exploration missions, novel measurement concepts, capable of detecting low concentrations of biomolecules with significantly improved sensitivity and specificity are required. Here we report on a novel analytical technique for the detection of extremely low concentrations of amino acids using ORIGIN, a compact and lightweight laser desorption ionization - mass spectrometer designed and developed for in situ space exploration missions. The identified unique mass fragmentation patterns of amino acids coupled to a multi-position laser scan, allows for a robust identification and quantification of amino acids. With a detection limit of a few fmol mm-2, and the possibility for sub-fmol detection sensitivity, this measurement technique excels current space exploration systems by three orders of magnitude. Moreover, our detection method is not affected by chemical alterations through surface minerals and/or salts, such as NaCl that is expected to be present at the percent level on ocean worlds. Our results demonstrate that ORIGIN is a promising instrument for the detection of signatures of life and ready for upcoming space missions, such as the Europa Lander.
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Affiliation(s)
| | - Valentine Grimaudo
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Pavel Moreno-García
- Interfacial Electrochemistry Group, Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Rustam Lukmanov
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Marek Tulej
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Ingo Leya
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Robert Lindner
- Life Support and Physical Sciences Instrumentation Section, European Space Agency, ESTEC, Bern, The Netherlands
| | - Peter Wurz
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Charles S Cockell
- School of Physics and Astronomy, UK Centre for Astrobiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Pascale Ehrenfreund
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands
- Space Policy Institute, George Washington University, 20052, Washington, DC, USA
| | - Andreas Riedo
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands
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57
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Baqué M, Napoli A, Claudia F, Moeller R, de Vera JP, Billi D. Carotenoid Raman Signatures Are Better Preserved in Dried Cells of the Desert Cyanobacterium Chroococcidiopsis than in Hydrated Counterparts after High-Dose Gamma Irradiation. Life (Basel) 2020; 10:E83. [PMID: 32521820 PMCID: PMC7345886 DOI: 10.3390/life10060083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 11/18/2022] Open
Abstract
Carotenoids are promising targets in our quest to search for life on Mars due to their biogenic origin and easy detection by Raman spectroscopy, especially with a 532 nm excitation thanks to resonance effects. Ionizing radiations reaching the surface and subsurface of Mars are however detrimental for the long-term preservation of biomolecules. We show here that desiccation can protect carotenoid Raman signatures in the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 even after high-dose gamma irradiation. Indeed, while the height of the carotenoids Raman peaks was considerably reduced in hydrated cells exposed to gamma irradiation, it remained stable in dried cells irradiated with the highest tested dose of 113 kGy of gamma rays, losing only 15-20% of its non-irradiated intensity. Interestingly, even though the carotenoid Raman signal of hydrated cells lost 90% of its non-irradiated intensity, it was still detectable after exposure to 113 kGy of gamma rays. These results add insights into the preservation potential and detectability limit of carotenoid-like molecules on Mars over a prolonged period of time and are crucial in supporting future missions carrying Raman spectrometers to Mars' surface.
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Affiliation(s)
- Mickael Baqué
- German Aerospace Center (DLR), Institute of Planetary Research, Department of Planetary Laboratories, Astrobiological Laboratories, 12489 Berlin, Germany; (M.B.); (J.-P.d.V.)
| | - Alessandro Napoli
- Department of Biology, Laboratory of Astrobiology and Molecular Biology of Cyanobacteria, University of Rome Tor Vergata, 00133 Rome, Italy; (A.N.); (C.F.)
| | - Fagliarone Claudia
- Department of Biology, Laboratory of Astrobiology and Molecular Biology of Cyanobacteria, University of Rome Tor Vergata, 00133 Rome, Italy; (A.N.); (C.F.)
| | - Ralf Moeller
- Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany;
| | - Jean-Pierre de Vera
- German Aerospace Center (DLR), Institute of Planetary Research, Department of Planetary Laboratories, Astrobiological Laboratories, 12489 Berlin, Germany; (M.B.); (J.-P.d.V.)
| | - Daniela Billi
- Department of Biology, Laboratory of Astrobiology and Molecular Biology of Cyanobacteria, University of Rome Tor Vergata, 00133 Rome, Italy; (A.N.); (C.F.)
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Carrier B, Beaty D, Meyer M, Blank J, Chou L, DasSarma S, Des Marais D, Eigenbrode J, Grefenstette N, Lanza N, Schuerger A, Schwendner P, Smith H, Stoker C, Tarnas J, Webster K, Bakermans C, Baxter B, Bell M, Benner S, Bolivar Torres H, Boston P, Bruner R, Clark B, DasSarma P, Engelhart A, Gallegos Z, Garvin Z, Gasda P, Green J, Harris R, Hoffman M, Kieft T, Koeppel A, Lee P, Li X, Lynch K, Mackelprang R, Mahaffy P, Matthies L, Nellessen M, Newsom H, Northup D, O'Connor B, Perl S, Quinn R, Rowe L, Sauterey B, Schneegurt M, Schulze-Makuch D, Scuderi L, Spilde M, Stamenković V, Torres Celis J, Viola D, Wade B, Walker C, Wiens R, Williams A, Williams J, Xu J. Mars Extant Life: What's Next? Conference Report. ASTROBIOLOGY 2020; 20:785-814. [PMID: 32466662 PMCID: PMC7307687 DOI: 10.1089/ast.2020.2237] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/24/2020] [Indexed: 05/19/2023]
Abstract
On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia ("oases"), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques-that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.
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Affiliation(s)
- B.L. Carrier
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - D.W. Beaty
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - J.G. Blank
- NASA Ames Research Center, Moffett Field, California, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - L. Chou
- Georgetown University, Washington, DC, USA
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - S. DasSarma
- Department of Microbiology and Immunology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | | | | | | | - N.L. Lanza
- Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - A.C. Schuerger
- University of Florida/Space Life Sciences Laboratory, Kennedy Space Center, Florida, USA
| | - P. Schwendner
- University of Florida/Space Life Sciences Laboratory, Kennedy Space Center, Florida, USA
| | - H.D. Smith
- NASA Ames Research Center, Moffett Field, California, USA
| | - C.R. Stoker
- NASA Ames Research Center, Moffett Field, California, USA
| | - J.D. Tarnas
- Brown University, Providence, Rhode Island, USA
| | - K.D. Webster
- Planetary Science Institute, Tucson, Arizona, USA
| | - C. Bakermans
- Pennsylvania State University, Altoona, Pennsylvania, USA
| | - B.K. Baxter
- Westminster College, Salt Lake City, Utah, USA
| | - M.S. Bell
- NASA Johnson Space Center, Houston, Texas, USA
| | - S.A. Benner
- Foundation for Applied Molecular Evolution, Alachua, Florida, USA
| | - H.H. Bolivar Torres
- Universidad Nacional Autonoma de Mexico, Coyoacan, Distrito Federal Mexico, Mexico
| | - P.J. Boston
- NASA Astrobiology Institute, NASA Ames Research Center, Moffett Field, California, USA
| | - R. Bruner
- Denver Museum of Nature and Science, Denver, Colorado, USA
| | - B.C. Clark
- Space Science Institute, Littleton, Colorado, USA
| | - P. DasSarma
- Department of Microbiology and Immunology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | | | - Z.E. Gallegos
- University of New Mexico, Albuquerque, New Mexico, USA
| | - Z.K. Garvin
- Princeton University, Princeton, New Jersey, USA
| | - P.J. Gasda
- Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - J.H. Green
- Texas Tech University, Lubbock, Texas, USA
| | - R.L. Harris
- Princeton University, Princeton, New Jersey, USA
| | - M.E. Hoffman
- University of New Mexico, Albuquerque, New Mexico, USA
| | - T. Kieft
- New Mexico Institute of Mining and Technology, Socorro, New Mexico, USA
| | | | - P.A. Lee
- College of Charleston, Charleston, South Carolina, USA
| | - X. Li
- University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - K.L. Lynch
- Lunar and Planetary Institute/USRA, Houston, Texas, USA
| | - R. Mackelprang
- California State University Northridge, Northridge, California, USA
| | - P.R. Mahaffy
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - L.H. Matthies
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - H.E. Newsom
- University of New Mexico, Albuquerque, New Mexico, USA
| | - D.E. Northup
- University of New Mexico, Albuquerque, New Mexico, USA
| | | | - S.M. Perl
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - R.C. Quinn
- NASA Ames Research Center, Moffett Field, California, USA
| | - L.A. Rowe
- Valparaiso University, Valparaiso, Indiana, USA
| | | | | | | | - L.A. Scuderi
- University of New Mexico, Albuquerque, New Mexico, USA
| | - M.N. Spilde
- University of New Mexico, Albuquerque, New Mexico, USA
| | - V. Stamenković
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - J.A. Torres Celis
- Universidad Nacional Autonoma de Mexico, Coyoacan, Distrito Federal Mexico, Mexico
| | - D. Viola
- NASA Ames Research Center, Moffett Field, California, USA
| | - B.D. Wade
- Michigan State University, East Lansing, Michigan, USA
| | - C.J. Walker
- Delaware State University, Dover, Delaware, USA
| | - R.C. Wiens
- Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | | | - J.M. Williams
- University of New Mexico, Albuquerque, New Mexico, USA
| | - J. Xu
- University of Texas, El Paso, Texas, USA
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Teece BL, George SC, Agbaje OBA, Jacquet SM, Brock GA. Mars Rover Techniques and Lower/Middle Cambrian Microbialites from South Australia: Construction, Biofacies, and Biogeochemistry. ASTROBIOLOGY 2020; 20:637-657. [PMID: 32159385 DOI: 10.1089/ast.2019.2110] [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: 06/10/2023]
Abstract
The Perseverance rover (Mars 2020) is equipped with an instrumental and analytical payload capable of identifying a broad range of organic molecules in geological samples. To determine the efficacy of these analytical techniques in recognizing important ecological and environmental signals in the rock record, this study utilized analogous equipment, including gas chromatography/mass spectrometry, Raman spectroscopy, X-ray fluorescence (XRF), Fourier transform infrared spectroscopy, along with macroscopic and petrographic observations, to examine early-middle Cambrian microbialites from the Arrowie Basin, South Australia. Morphological and petrographic observations of these carbonate successions reveal evidence of hypersaline-restricted environments. Microbialites have undergone moderate diagenesis, as supported by XRF data that show mineral assemblages, including celestine and the illitization of smectite. Raman spectral data, carbon preference indices of ∼1, and the methylphenanthrene index place the samples in the prehnite/pumpellyite metamorphic facies. Pristane and phytane are the only biomarkers that were detected in the least thermally mature samples. This research demonstrates a multitechnique approach that can yield significant geological, depositional, paleobiological, and diagenetic information that has important implications for planning future astrobiological exploration.
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Affiliation(s)
- Bronwyn L Teece
- Australian Centre for Astrobiology, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
- Department of Earth and Environmental Sciences and MQ Marine Research Centre, Macquarie University, Sydney, Australia
- Department of Biological Sciences, Macquarie University, Sydney, Australia
| | - Simon C George
- Department of Earth and Environmental Sciences and MQ Marine Research Centre, Macquarie University, Sydney, Australia
| | - Oluwatoosin Bunmi A Agbaje
- Department of Earth and Environmental Sciences and MQ Marine Research Centre, Macquarie University, Sydney, Australia
- Department of Biological Sciences, Macquarie University, Sydney, Australia
- Department of Earth Sciences, Palaeobiology, Uppsala University, Uppsala, Sweden
| | - Sarah M Jacquet
- Department of Biological Sciences, Macquarie University, Sydney, Australia
- Department of Geological Sciences, University of Missouri, Columbia, Missouri
| | - Glenn A Brock
- Department of Biological Sciences, Macquarie University, Sydney, Australia
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60
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Longo A, Damer B. Factoring Origin of Life Hypotheses into the Search for Life in the Solar System and Beyond. Life (Basel) 2020; 10:E52. [PMID: 32349245 PMCID: PMC7281141 DOI: 10.3390/life10050052] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 01/13/2023] Open
Abstract
Two widely-cited alternative hypotheses propose geological localities and biochemical mechanisms for life's origins. The first states that chemical energy available in submarine hydrothermal vents supported the formation of organic compounds and initiated primitive metabolic pathways which became incorporated in the earliest cells; the second proposes that protocells self-assembled from exogenous and geothermally-delivered monomers in freshwater hot springs. These alternative hypotheses are relevant to the fossil record of early life on Earth, and can be factored into the search for life elsewhere in the Solar System. This review summarizes the evidence supporting and challenging these hypotheses, and considers their implications for the search for life on various habitable worlds. It will discuss the relative probability that life could have emerged in environments on early Mars, on the icy moons of Jupiter and Saturn, and also the degree to which prebiotic chemistry could have advanced on Titan. These environments will be compared to ancient and modern terrestrial analogs to assess their habitability and biopreservation potential. Origins of life approaches can guide the biosignature detection strategies of the next generation of planetary science missions, which could in turn advance one or both of the leading alternative abiogenesis hypotheses.
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Affiliation(s)
- Alex Longo
- National Aeronautics and Space Administration Headquarters, Washington, DC 20546, USA
- Department of Geology, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Bruce Damer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA or
- Digital Space Research, Boulder Creek, CA 95006, USA
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61
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Gong J, Myers KD, Munoz-Saez C, Homann M, Rouillard J, Wirth R, Schreiber A, van Zuilen MA. Formation and Preservation of Microbial Palisade Fabric in Silica Deposits from El Tatio, Chile. ASTROBIOLOGY 2020; 20:500-524. [PMID: 31663774 PMCID: PMC7133459 DOI: 10.1089/ast.2019.2025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 09/19/2019] [Indexed: 05/26/2023]
Abstract
Palisade fabric is a ubiquitous texture of silica sinter found in low temperature (<40°C) regimes of hot spring environments, and it is formed when populations of filamentous microorganisms act as templates for silica polymerization. Although it is known that postdepositional processes such as biological degradation and dewatering can strongly affect preservation of these fabrics, the impact of extreme aridity has so far not been studied in detail. Here, we report a detailed analysis of recently silicified palisade fabrics from a geyser in El Tatio, Chile, tracing the progressive degradation of microorganisms within the silica matrix. This is complemented by heating experiments of natural sinter samples to assess the role of diagenesis. Sheathed cyanobacteria, identified as Leptolyngbya sp., were found to be incorporated into silica sinter by irregular cycles of wetting, evaporation, and mineral precipitation. Transmission electron microscopy analyses revealed that nanometer-sized silica particles are filling the pore space within individual cyanobacterial sheaths, giving rise to their structural rigidity to sustain a palisade fabric framework. Diagenesis experiments further show that the sheaths of the filaments are preferentially preserved relative to the trichomes, and that the amount of water present within the sinter is an important factor for overall preservation during burial. This study confirms that palisade fabrics are efficiently generated in a highly evaporative geothermal field, and that these biosignatures can be most effectively preserved under dry diagenetic conditions.
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Affiliation(s)
- Jian Gong
- Equipe Géomicrobiologie, Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Kimberly D. Myers
- Equipe Géomicrobiologie, Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Carolina Munoz-Saez
- Departamento de Geologia, FCFM, Centro de Excelencia en Geotermia de los Andes (CEGA), Universidad de Chile, Santiago, Chile
| | - Martin Homann
- CNRS-UMR6538 Laboratoire Géosciences Océan, European Institute for Marine Studies, Technopôle Brest-Iroise, Plouzané, France
| | - Joti Rouillard
- Equipe Géomicrobiologie, Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France
| | - Richard Wirth
- GeoForschungsZentrum, Section 3.5 Interface Geochemistry, D-14473, Potsdam, Germany
| | - Anja Schreiber
- GeoForschungsZentrum, Section 3.5 Interface Geochemistry, D-14473, Potsdam, Germany
| | - Mark A. van Zuilen
- Equipe Géomicrobiologie, Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France
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62
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Teece BL, George SC, Djokic T, Campbell KA, Ruff SW, Van Kranendonk MJ. Biomolecules from Fossilized Hot Spring Sinters: Implications for the Search for Life on Mars. ASTROBIOLOGY 2020; 20:537-551. [PMID: 32155343 DOI: 10.1089/ast.2018.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hot spring environments are commonly dominated by silica sinters that precipitate by the rapid cooling of silica-saturated fluids and the activity of microbial communities. However, the potential for preservation of organic traces of life in silica sinters back through time is not well understood. This is important for the exploration of early life on Earth and possibly Mars. Most previous studies have focused on physical preservation in samples <900 years old, with only a few focused on organic biomarkers. In this study, we investigate the organic geochemistry of hot spring samples from El Tatio, Chile and the Taupo Volcanic Zone, with ages varying from modern to ∼9.4 ka. Results show that all samples contain opaline silica and contain hydrocarbons that are indicative of a cyanobacterial origin. A ∼3 ka recrystallized, quartz-bearing sample also contains traces of cyanobacterial biomarkers. No aromatic compounds were detected in a ∼9.4 ka opal-A sample or in a modern sinter breccia sample. All other samples contain naphthalene, with one sample also containing other polyaromatic hydrocarbons. These aromatic hydrocarbons have a thermally mature distribution that is perhaps reflective of geothermal fluids migrating from deep, rather than surface, reservoirs. These data show that hot spring sinters can preserve biomolecules from the local microbial community, and that crystallinity rather than age may be the determining factor in their preservation. This research provides support for the exploration for biomolecules in opaline silica deposits on Mars.
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Affiliation(s)
- Bronwyn L Teece
- Australian Centre for Astrobiology (ACA) and PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Simon C George
- Department of Earth and Environmental Sciences and MQ Planetary Research Centre, Macquarie University, Sydney, Australia
| | - Tara Djokic
- Australian Centre for Astrobiology (ACA) and PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Kathleen A Campbell
- School of Environment and Te Ao Mārama-Centre for Fundamental Inquiry, Faculty of Science, The University of Auckland, Auckland, New Zealand
| | - Steven W Ruff
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | - Martin J Van Kranendonk
- Australian Centre for Astrobiology (ACA) and PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney, Sydney, Australia
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63
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Maggiori C, Stromberg J, Blanco Y, Goordial J, Cloutis E, García-Villadangos M, Parro V, Whyte L. The Limits, Capabilities, and Potential for Life Detection with MinION Sequencing in a Paleochannel Mars Analog. ASTROBIOLOGY 2020; 20:375-393. [PMID: 31976742 DOI: 10.1089/ast.2018.1964] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
No instrument capable of direct life detection has been included on a mission payload to Mars since NASA's Viking missions in the 1970s. This prevents us from discovering whether life is or ever was present on Mars. DNA is an ideal target biosignature since it is unambiguous, nonspecific, and readily detectable with nanopore sequencing. Here, we present a proof-of-concept utilization of the Oxford Nanopore Technologies (ONT) MinION sequencer for direct life detection and show how it can complement results from established space mission instruments. We used nanopore sequencing data from the MinION to detect and characterize the microbial life in a set of paleochannels near Hanksville, UT, with supporting data from X-ray diffraction, reflectance spectroscopy, Raman spectroscopy, and Life Detector Chip (LDChip) microarray immunoassay analyses. These paleochannels are analogs to martian sinuous ridges. The MinION-generated metagenomes reveal a rich microbial community dominated by bacteria and containing radioresistant, psychrophilic, and halophilic taxa. With spectral data and LDChip immunoassays, these metagenomes were linked to the surrounding Mars analog environment and potential metabolisms (e.g., methane production and perchlorate reduction). This shows a high degree of synergy between these techniques for detecting and characterizing biosignatures. We also resolved a prospective lower limit of ∼0.001 ng of DNA required for successful sequencing. This work represents the first determination of the MinION's DNA detection limits beyond ONT recommendations and the first whole metagenome analysis of a sinuous ridge analog.
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Affiliation(s)
- Catherine Maggiori
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Quebec, Canada
| | | | - Yolanda Blanco
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - Jacqueline Goordial
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Quebec, Canada
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine
| | - Edward Cloutis
- Department of Geography, Faculty of Science, University of Winnipeg, Winnipeg, Canada
| | | | - Victor Parro
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - Lyle Whyte
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Quebec, Canada
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64
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Poulet F, Gross C, Horgan B, Loizeau D, Bishop JL, Carter J, Orgel C. Mawrth Vallis, Mars: A Fascinating Place for Future In Situ Exploration. ASTROBIOLOGY 2020; 20:199-234. [PMID: 31916851 DOI: 10.1089/ast.2019.2074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
After the successful landing of the Mars Science Laboratory rover, both NASA and ESA initiated a selection process for potential landing sites for the Mars2020 and ExoMars missions, respectively. Two ellipses located in the Mawrth Vallis region were proposed and evaluated during a series of meetings (three for Mars2020 mission and five for ExoMars). We describe here the regional context of the two proposed ellipses as well as the framework of the objectives of these two missions. Key science targets of the ellipses and their astrobiological interests are reported. This work confirms that the proposed ellipses contain multiple past martian wet environments of a subaerial, subsurface, and/or subaqueous character, in which to probe the past climate of Mars; build a broad picture of possible past habitable environments; evaluate their exobiological potentials; and search for biosignatures in well-preserved rocks. A mission scenario covering several key investigations during the nominal mission of each rover is also presented, as well as descriptions of how the site fulfills the science requirements and expectations of in situ martian exploration. These serve as a basis for potential future exploration of the Mawrth Vallis region with new missions and describe opportunities for human exploration of Mars in terms of resources and science discoveries.
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Affiliation(s)
- François Poulet
- Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Orsay, France
| | - Christoph Gross
- Institute of Geological Sciences, Planetary Sciences and Remote Sensing Group, Freie Universität Berlin, Berlin, Germany
| | | | - Damien Loizeau
- Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Orsay, France
| | | | - John Carter
- Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Orsay, France
| | - Csilla Orgel
- Institute of Geological Sciences, Planetary Sciences and Remote Sensing Group, Freie Universität Berlin, Berlin, Germany
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65
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Guido DM, Campbell KA. Plastic Silica Conglomerate with an Extremophile Microbial Matrix in a Hot-Water Stream Paleoenvironment. ASTROBIOLOGY 2019; 19:1433-1441. [PMID: 31059288 DOI: 10.1089/ast.2018.1998] [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: 06/09/2023]
Abstract
A new and unusual type of fossil, siliceous hot-spring deposit (sinter)-comprising monomictic, quartzose conglomerate encrusted with silicified microbial laminates-has been recognized in distal portions of Jurassic and Miocene paleo-geothermal fields of South and North America, respectively. The siliceous clasts are inferred to have originated as conduit-delivered hydrothermal silica gel, owing to their general plastic morphologies, which were then locally reworked and redistributed in geothermally influenced stream paleoenvironments. Today, hot-spring-fed streams and creeks, in places with silica-armored pavements, host microbial mats coating streambeds and/or growing over, and silicifying at, stream air-water interfaces, for example, in Yellowstone National Park (USA) and Waimangu Volcanic Valley (New Zealand). However, the modern deposits do not contain the plastically deformed silica cobbles evident in Mesozoic and Cenozoic examples described herein. Moreover, the fossil microbial laminates of this study are relatively dense and strongly coat the silica cobbles, suggesting the mats stabilized the clasts under fully submerged and hot, high-energy conditions. Thus, this new sinter facies, typically found a few kilometers from main spring-vent areas, is a perhaps unexpected extreme environment in which life took hold in hydrothermal-fluvial settings of the past, and may serve as an additional target in the search for fossil biosignatures of early Earth and possibly Mars.
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Affiliation(s)
- Diego M Guido
- CONICET and Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Instituto de Recursos Minerales (INREMI), La Plata, Argentina
| | - Kathleen A Campbell
- School of Environment and Te Ao Mārama-Centre for Fundamental Inquiry, Faculty of Science, University of Auckland, Auckland, New Zealand
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66
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Shen J, Zerkle AL, Stueeken E, Claire MW. Nitrates as a Potential N Supply for Microbial Ecosystems in a Hyperarid Mars Analog System. Life (Basel) 2019; 9:life9040079. [PMID: 31635024 PMCID: PMC6958444 DOI: 10.3390/life9040079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/08/2019] [Accepted: 10/17/2019] [Indexed: 11/16/2022] Open
Abstract
Nitrate is common in Mars sediments owing to long-term atmospheric photolysis, oxidation, and potentially, impact shock heating. The Atacama Desert in Chile, which is the driest region on Earth and rich in nitrate deposits, is used as a Mars analog in this study to explore the potential effects of high nitrate levels on growth of extremophilic ecosystems. Seven study sites sampled across an aridity gradient in the Atacama Desert were categorized into 3 clusters—hyperarid, middle, and arid sites—as defined by essential soil physical and chemical properties. Intriguingly, the distribution of nitrate concentrations in the shallow subsurface suggests that the buildup of nitrate is not solely controlled by precipitation. Correlations of nitrate with SiO2/Al2O3 and grain sizes suggest that sedimentation rates may also be important in controlling nitrate distribution. At arid sites receiving more than 10 mm/yr precipitation, rainfall shows a stronger impact on biomass than nitrate does. However, high nitrate to organic carbon ratios are generally beneficial to N assimilation, as evidenced both by soil geochemistry and enriched culturing experiments. This study suggests that even in the absence of precipitation, nitrate levels on a more recent, hyperarid Mars could be sufficiently high to benefit potentially extant Martian microorganisms.
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Affiliation(s)
- Jianxun Shen
- School of Earth and Environmental Sciences and Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.
| | - Aubrey L Zerkle
- School of Earth and Environmental Sciences and Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.
| | - Eva Stueeken
- School of Earth and Environmental Sciences and Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.
| | - Mark W Claire
- School of Earth and Environmental Sciences and Centre for Exoplanet Science, University of St Andrews, St Andrews KY16 9AL, Scotland, UK.
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67
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Chan MA, Hinman NW, Potter-McIntyre SL, Schubert KE, Gillams RJ, Awramik SM, Boston PJ, Bower DM, Des Marais DJ, Farmer JD, Jia TZ, King PL, Hazen RM, Léveillé RJ, Papineau D, Rempfert KR, Sánchez-Román M, Spear JR, Southam G, Stern JC, Cleaves HJ. Deciphering Biosignatures in Planetary Contexts. ASTROBIOLOGY 2019; 19:1075-1102. [PMID: 31335163 PMCID: PMC6708275 DOI: 10.1089/ast.2018.1903] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 03/10/2019] [Indexed: 05/05/2023]
Abstract
Microbial life permeates Earth's critical zone and has likely inhabited nearly all our planet's surface and near subsurface since before the beginning of the sedimentary rock record. Given the vast time that Earth has been teeming with life, do astrobiologists truly understand what geological features untouched by biological processes would look like? In the search for extraterrestrial life in the Universe, it is critical to determine what constitutes a biosignature across multiple scales, and how this compares with "abiosignatures" formed by nonliving processes. Developing standards for abiotic and biotic characteristics would provide quantitative metrics for comparison across different data types and observational time frames. The evidence for life detection falls into three categories of biosignatures: (1) substances, such as elemental abundances, isotopes, molecules, allotropes, enantiomers, minerals, and their associated properties; (2) objects that are physical features such as mats, fossils including trace-fossils and microbialites (stromatolites), and concretions; and (3) patterns, such as physical three-dimensional or conceptual n-dimensional relationships of physical or chemical phenomena, including patterns of intermolecular abundances of organic homologues, and patterns of stable isotopic abundances between and within compounds. Five key challenges that warrant future exploration by the astrobiology community include the following: (1) examining phenomena at the "right" spatial scales because biosignatures may elude us if not examined with the appropriate instrumentation or modeling approach at that specific scale; (2) identifying the precise context across multiple spatial and temporal scales to understand how tangible biosignatures may or may not be preserved; (3) increasing capability to mine big data sets to reveal relationships, for example, how Earth's mineral diversity may have evolved in conjunction with life; (4) leveraging cyberinfrastructure for data management of biosignature types, characteristics, and classifications; and (5) using three-dimensional to n-D representations of biotic and abiotic models overlain on multiple overlapping spatial and temporal relationships to provide new insights.
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Affiliation(s)
- Marjorie A. Chan
- Department of Geology & Geophysics, University of Utah, Salt Lake City, Utah
| | - Nancy W. Hinman
- Department of Geosciences, University of Montana, Missoula, Montana
| | | | - Keith E. Schubert
- Department of Electrical and Computer Engineering, Baylor University, Waco, Texas
| | - Richard J. Gillams
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Electronics and Computer Science, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Stanley M. Awramik
- Department of Earth Science, University of California, Santa Barbara, Santa Barbara, California
| | - Penelope J. Boston
- NASA Astrobiology Institute, NASA Ames Research Center, Moffett Field, California
| | - Dina M. Bower
- Department of Astronomy, University of Maryland College Park (CRESST), College Park, Maryland
- NASA Goddard Space Flight Center, Greenbelt, Maryland
| | | | - Jack D. Farmer
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | - Tony Z. Jia
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Penelope L. King
- Research School of Earth Sciences, The Australian National University, Canberra, Australia
| | - Robert M. Hazen
- Geophysical Laboratory, Carnegie Institution for Science, Washington, District of Columbia
| | - Richard J. Léveillé
- Department of Earth and Planetary Sciences, McGill University, Montreal, Canada
- Geosciences Department, John Abbott College, Sainte-Anne-de-Bellevue, Canada
| | - Dominic Papineau
- London Centre for Nanotechnology, University College London, London, United Kingdom
- Department of Earth Sciences, University College London, London, United Kingdom
- Centre for Planetary Sciences, University College London, London, United Kingdom
- BioGeology and Environmental Geology State Key Laboratory, School of Earth Sciences, China University of Geosciences, Wuhan, China
| | - Kaitlin R. Rempfert
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado
| | - Mónica Sánchez-Román
- Earth Sciences Department, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado
| | - Gordon Southam
- School of Earth and Environmental Sciences, The University of Queensland, St. Lucia, Queensland, Australia
| | | | - Henderson James Cleaves
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Program in Interdisciplinary Studies, Institute for Advanced Study, Princeton, New Jersey
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68
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Stevens AH, McDonald A, de Koning C, Riedo A, Preston LJ, Ehrenfreund P, Wurz P, Cockell CS. Detectability of biosignatures in a low-biomass simulation of martian sediments. Sci Rep 2019; 9:9706. [PMID: 31273294 PMCID: PMC6609699 DOI: 10.1038/s41598-019-46239-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/18/2019] [Indexed: 01/19/2023] Open
Abstract
Discovery of a remnant habitable environment by the Mars Science Laboratory in the sedimentary record of Gale Crater has reinvigorated the search for evidence of martian life. In this study, we used a simulated martian mudstone material, based on data from Gale Crater, that was inoculated and cultured over several months and then dried and pressed. The simulated mudstone was analysed with a range of techniques to investigate the detectability of biosignatures. Cell counting and DNA extraction showed a diverse but low biomass microbial community that was highly dispersed. Pellets were analysed with bulk Elemental Analysis – Isotope Ratio Mass Spectrometry (EA-IRMS), high-resolution Laser-ablation Ionisation Mass Spectrometry (LIMS), Raman spectroscopy and Fourier Transform InfraRed (FTIR) spectroscopy, which are all techniques of relevance to current and future space missions. Bulk analytical techniques were unable to differentiate between inoculated samples and abiotic controls, despite total levels of organic carbon comparable with that of the martian surface. Raman spectroscopy, FTIR spectroscopy and LIMS, which are high sensitivity techniques that provide chemical information at high spatial resolution, retrieved presumptive biosignatures but these remained ambiguous and the sedimentary matrix presented challenges for all techniques. This suggests challenges for detecting definitive evidence for life, both in the simulated lacustrine environment via standard microbiological techniques and in the simulated mudstone via analytical techniques with relevance to robotic missions. Our study suggests that multiple co-incident high-sensitivity techniques that can scan the same micrometre-scale spots are required to unambiguously detect biosignatures, but the spatial coverage of these techniques needs to be high enough not to miss individual cellular-scale structures in the matrix.
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Affiliation(s)
- Adam H Stevens
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
| | - Alison McDonald
- School of Engineering, Bioimaging Facility, University of Edinburgh, Edinburgh, UK
| | - Coen de Koning
- Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands
| | - Andreas Riedo
- Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands.,Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Louisa J Preston
- Dept. of Earth and Planetary Sciences, Birkbeck, University of London, London, UK
| | - Pascale Ehrenfreund
- Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands
| | - Peter Wurz
- Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
| | - Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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69
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Chaves Torres L, Kaur G, Melbourne LA, Pancost RD. Selective chemical degradation of silica sinters of the Taupo Volcanic Zone (New Zealand). Implications for early Earth and Astrobiology. GEOBIOLOGY 2019; 17:449-464. [PMID: 31020785 DOI: 10.1111/gbi.12340] [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: 10/04/2018] [Revised: 02/26/2019] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
Most organic matter (OM) on Earth occurs as kerogen-like materials, that is naturally formed macromolecules insoluble with standard organic solvents. The formation of this insoluble organic matter (IOM) is a topic of much interest, especially when it limits the detection of compounds of geomicrobiological interest. For example, studies that search for biomarker evidence of life on early Earth or other planets usually use solvent-based extractions. This leaves behind a pool of OM as unexplored post-extraction residues, potentially containing diagnostic biomarkers. Since the IOM has an enhanced potential for preservation compared to soluble OM, analysing IOM-released biomarkers can also provide even deeper insights into the ecology of ancient settings, with implications for early Earth and Astrobiology investigations. Here, we analyse the prokaryotic lipid biosignature within soluble and IOM of the Taupo Volcanic Zone (TVZ) silica sinters, which are key analogues in the search for life. We apply sequential solvent extractions and a selective chemical degradation upon the post-solvent extraction residue. Moreover, we compare the IOM from TVZ sinters to analogous studies on peat and marine sediments to assess patterns in OM insolubilisation across the geosphere. Consistent with previous work, we find significant but variable proportions-1%-45% of the total prokaryotic lipids recovered-associated with IOM fractions. This occurs even in recently formed silica sinters, likely indicating inherent cell insolubility. Moreover, archaeal lipids seem more prone to insolubilisation as compared to the bacterial analogues, which might enhance their preservation and also bias overall biomarkers interpretation. These observations are similar to those observed in other settings, confirming that even in a setting where the OM derives predominantly from prokaryotic sources, patterns of IOM formation/occurrence are conserved. Differences with other settings, however, such as the occurrence of archaeol in IOM fractions, could be indicative of different mechanisms for IOM formation that merit further exploration.
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Affiliation(s)
- Lidia Chaves Torres
- Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol, UK
- Cabot Institute, University of Bristol, Bristol, UK
| | - Gurpreet Kaur
- Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol, UK
- Cabot Institute, University of Bristol, Bristol, UK
| | - Leanne A Melbourne
- Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol, UK
- Cabot Institute, University of Bristol, Bristol, UK
| | - Richard D Pancost
- Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol, UK
- Cabot Institute, University of Bristol, Bristol, UK
- School of Earth Sciences, University of Bristol, Bristol, UK
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70
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Sapers HM, Razzell Hollis J, Bhartia R, Beegle LW, Orphan VJ, Amend JP. The Cell and the Sum of Its Parts: Patterns of Complexity in Biosignatures as Revealed by Deep UV Raman Spectroscopy. Front Microbiol 2019; 10:679. [PMID: 31156562 PMCID: PMC6527968 DOI: 10.3389/fmicb.2019.00679] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 03/18/2019] [Indexed: 01/27/2023] Open
Abstract
The next NASA-led Mars mission (Mars 2020) will carry a suite of instrumentation dedicated to investigating Martian history and the in situ detection of potential biosignatures. SHERLOC, a deep UV Raman/Fluorescence spectrometer has the ability to detect and map the distribution of many organic compounds, including the aromatic molecules that are fundamental building blocks of life on Earth, at concentrations down to 1 ppm. The mere presence of organic compounds is not a biosignature: there is widespread distribution of reduced organic molecules in the Solar System. Life utilizes a select few of these molecules creating conspicuous enrichments of specific molecules that deviate from the distribution expected from purely abiotic processes. The detection of far from equilibrium concentrations of a specific subset of organic molecules, such as those uniquely enriched by biological processes, would comprise a universal biosignature independent of specific terrestrial biochemistry. The detectability and suitability of a small subset of organic molecules to adequately describe a living system is explored using the bacterium Escherichia coli as a model organism. The DUV Raman spectra of E. coli cells are dominated by the vibrational modes of the nucleobases adenine, guanine, cytosine, and thymine, and the aromatic amino acids tyrosine, tryptophan, and phenylalanine. We demonstrate that not only does the deep ultraviolet (DUV) Raman spectrum of E. coli reflect a distinct concentration of specific organic molecules, but that a sufficient molecular complexity is required to deconvolute the cellular spectrum. Furthermore, a linear combination of the DUV resonant compounds is insufficient to fully describe the cellular spectrum. The residual in the cellular spectrum indicates that DUV Raman spectroscopy enables differentiating between the presence of biomolecules and the complex uniquely biological organization and arrangements of these molecules in living systems. This study demonstrates the ability of DUV Raman spectroscopy to interrogate a complex biological system represented in a living cell, and differentiate between organic detection and a series of Raman features that derive from the molecular complexity inherent to life constituting a biosignature.
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Affiliation(s)
- Haley M. Sapers
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Joseph Razzell Hollis
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Rohit Bhartia
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Luther W. Beegle
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Victoria J. Orphan
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
| | - Jan P. Amend
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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71
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Parro V, Puente-Sánchez F, Cabrol NA, Gallardo-Carreño I, Moreno-Paz M, Blanco Y, García-Villadangos M, Tambley C, Tilot VC, Thompson C, Smith E, Sobrón P, Demergasso CS, Echeverría-Vega A, Fernández-Martínez MÁ, Whyte LG, Fairén AG. Microbiology and Nitrogen Cycle in the Benthic Sediments of a Glacial Oligotrophic Deep Andean Lake as Analog of Ancient Martian Lake-Beds. Front Microbiol 2019; 10:929. [PMID: 31130930 PMCID: PMC6509559 DOI: 10.3389/fmicb.2019.00929] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 04/12/2019] [Indexed: 02/06/2023] Open
Abstract
Potential benthic habitats of early Mars lakes, probably oligotrophic, could range from hydrothermal to cold sediments. Dynamic processes in the water column (such as turbidity or UV penetration) as well as in the benthic bed (temperature gradients, turbation, or sedimentation rate) contribute to supply nutrients to a potential microbial ecosystem. High altitude, oligotrophic, and deep Andean lakes with active deglaciation processes and recent or past volcanic activity are natural models to assess the feasibility of life in other planetary lake/ocean environments and to develop technology for their exploration. We sampled the benthic sediments (down to 269 m depth) of the oligotrophic lake Laguna Negra (Central Andes, Chile) to investigate its ecosystem through geochemical, biomarker profiling, and molecular ecology studies. The chemistry of the benthic water was similar to the rest of the water column, except for variable amounts of ammonium (up to 2.8 ppm) and nitrate (up to 0.13 ppm). A life detector chip with a 300-antibody microarray revealed the presence of biomass in the form of exopolysaccharides and other microbial markers associated to several phylogenetic groups and potential microaerobic and anaerobic metabolisms such as nitrate reduction. DNA analyses showed that 27% of the Archaea sequences corresponded to a group of ammonia-oxidizing archaea (AOA) similar (97%) to Nitrosopumilus spp. and Nitrosoarchaeum spp. (Thaumarchaeota), and 4% of Bacteria sequences to nitrite-oxidizing bacteria from the Nitrospira genus, suggesting a coupling between ammonia and nitrite oxidation. Mesocosm experiments with the specific AOA inhibitor 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) demonstrated an AOA-associated ammonia oxidation activity with the simultaneous accumulation of nitrate and sulfate. The results showed a rich benthic microbial community dominated by microaerobic and anaerobic metabolisms thriving under aphotic, low temperature (4°C), and relatively high pressure, that might be a suitable terrestrial analog of other planetary settings.
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Affiliation(s)
- Victor Parro
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
| | | | - Nathalie A. Cabrol
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
- NASA Ames Research Center, Mountain View, CA, United States
| | | | | | | | | | | | - Virginie C. Tilot
- Instituto Español de Oceanografía (IEO), Málaga, Spain
- Muséum National d’Histoire Naturelle, Paris, France
| | - Cody Thompson
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
| | - Eric Smith
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
| | - Pablo Sobrón
- SETI Institute, Carl Sagan Center, Mountain View, CA, United States
| | | | - Alex Echeverría-Vega
- Centro de Biotecnología, Universidad Católica del Norte, Antofagasta, Chile
- Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
| | | | - Lyle G. Whyte
- Department of Natural Resource Sciences, McGill University, Montreal, QC, Canada
| | - Alberto G. Fairén
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Department of Astronomy, Cornell University, Ithaca, NY, United States
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72
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Chan MA, Bowen BB, Corsetti FA, Farrand WH, Law ES, Newsom HE, Perl SM, Spear JR, Thompson DR. Exploring, Mapping, and Data Management Integration of Habitable Environments in Astrobiology. Front Microbiol 2019; 10:147. [PMID: 30891006 PMCID: PMC6412026 DOI: 10.3389/fmicb.2019.00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/21/2019] [Indexed: 11/17/2022] Open
Abstract
New approaches to blending geoscience, planetary science, microbiology-geobiology/ecology, geoinformatics and cyberinfrastructure technology disciplines in a holistic effort can be transformative to astrobiology explorations. Over the last two decades, overwhelming orbital evidence has confirmed the abundance of authigenic (in situ, formed in place) minerals on Mars. On Earth, environments where authigenic minerals form provide a substrate for the preservation of microbial life. Similarly, extraterrestrial life is likely to be preserved where crustal minerals can record and preserve the biochemical mechanisms (i.e., biosignatures). The search for astrobiological evidence on Mars has focused on identifying past or present habitable environments - places that could support some semblance of life. Thus, authigenic minerals represent a promising habitable environment where extraterrestrial life could be recorded and potentially preserved over geologic time scales. Astrobiology research necessarily takes place over vastly different scales; from molecules to viruses and microbes to those of satellites and solar system exploration, but the differing scales of analyses are rarely connected quantitatively. The mismatch between the scales of these observations- from the macro- satellite mineralogical observations to the micro- microbial observations- limits the applicability of our astrobiological understanding as we search for records of life beyond Earth. Each-scale observation requires knowledge of the geologic context and the environmental parameters important for assessing habitability. Exploration efforts to search for extraterrestrial life should attempt to quantify both the geospatial context and the temporal/spatial relationships between microbial abundance and diversity within authigenic minerals at multiple scales, while assimilating resolutions from satellite observations to field measurements to microscopic analyses. Statistical measures, computer vision, and the geospatial synergy of Geographic Information Systems (GIS), can allow analyses of objective data-driven methods to locate, map, and predict where the "sweet spots" of habitable environments occur at multiple scales. This approach of science information architecture or an "Astrobiology Information System" can provide the necessary maps to guide researchers to discoveries via testing, visualizing, documenting, and collaborating on significant data relationships that will advance explorations for evidence of life in our solar system and beyond.
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Affiliation(s)
- Marjorie A. Chan
- Department of Geology and Geophysics, The University of Utah, Salt Lake City, UT, United States
| | - Brenda B. Bowen
- Department of Geology and Geophysics, The University of Utah, Salt Lake City, UT, United States
| | - Frank A. Corsetti
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | | | - Emily S. Law
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Horton E. Newsom
- Department Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, United States
| | - Scott M. Perl
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - David R. Thompson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
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73
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Floyd MAM, Williams AJ, Grubisic A, Emerson D. Metabolic Processes Preserved as Biosignatures in Iron-Oxidizing Microorganisms: Implications for Biosignature Detection on Mars. ASTROBIOLOGY 2019; 19:40-52. [PMID: 30044121 PMCID: PMC6338579 DOI: 10.1089/ast.2017.1745] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Iron-oxidizing bacteria occupy a distinct environmental niche. These chemolithoautotrophic organisms require very little oxygen (when neutrophilic) or outcompete oxygen for access to Fe(II) (when acidophilic). The utilization of Fe(II) as an electron donor makes them strong analog organisms for any potential life that could be found on Mars. Despite their importance to the elucidation of early life on, and potentially beyond, Earth, many details of their metabolism remain unknown. By using on-line thermochemolysis and gas chromatography-mass spectrometry (GC-MS), a distinct signal for a low-molecular-weight molecule was discovered in multiple iron-oxidizing isolates as well as several iron-dominated environmental samples, from freshwater and marine environments and in both modern and older iron rock samples. This GC-MS signal was neither detected in organisms that did not use Fe(II) as an electron donor nor present in iron mats in which organic carbon was destroyed by heating. Mass spectral analysis indicates that the molecule bears the hallmarks of a pterin-bearing molecule. Genomic analysis has previously identified a molybdopterin that could be part of the electron transport chain in a number of lithotrophic iron-oxidizing bacteria, suggesting one possible source for this signal is the pterin component of this protein. The rock samples indicate the possibility that the molecule can be preserved within lithified sedimentary rocks. The specificity of the signal to organisms requiring iron in their metabolism makes this a novel biosignature with which to investigate both the evolution of life on ancient Earth and potential life on Mars.
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Affiliation(s)
| | - Amy J Williams
- 1 NASA Goddard Space Flight Center , Greenbelt, Maryland
- 2 Department of Physics, Astronomy, and Geosciences, Towson University , Towson, Maryland
| | | | - David Emerson
- 3 Bigelow Laboratory for Ocean Sciences , East Boothbay, Maine
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74
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Identification of Thiobacillus bacteria in agricultural soil in Iran using the 16S rRNA gene. Mol Biol Rep 2018; 45:1723-1731. [PMID: 30443822 DOI: 10.1007/s11033-018-4316-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 08/16/2018] [Indexed: 10/27/2022]
Abstract
Thiobacillus, as useful soil bacteria, plays an important role in sulfur cycling. The purpose of this study was to identify the species Thiobacillus thioparus, Thiobacillus novellas and Thiobacillus denitrificans in rainfed and irrigated lands soil in Ajabshir, Ilam, Qorveh, Rojintaak, Sonqor, Kermanshah and Research Farm of Razi University in Iran. Sampling was performed as randomized completely with three replications at depth of 0-30 cm. The Thiobacillus species were determined via 16S rRNA characteristics. The results of agarose gel electrophoresis indicated that T. thioparus was the highest amount in the irrigated land in Research Farm and its lowest amount was in the Rojintaak rainfed land. These species not found in four locations and conditions including the Ajabshir irrigated, Qorveh rainfed, Research Farm rainfed and Rojintaak irrigated lands. The results of the T. novellas indicated that this was found in Ilam irrigated, Qorveh rainfed, Research Farm irrigated, Rojintaak irrigated and Rojintaak rainfed lands. The highest and lowest amount of T. novellas was indicated in the Rojintaak and Ilam irrigated lands respectively. The T. denitrificans gene showed that this bacterium was observed only in both samples of Ajabshir. Our study showed that Thiobacillus was not detected in all of the soils. If sulfur fertilizer is given to the soil without this bacterium, it is necessary to use sulfur fertilizer with Thiobacillus bacteria inoculation for better sulfur oxidation.
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75
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Hynek BM, Rogers KL, Antunovich M, Avard G, Alvarado GE. Lack of Microbial Diversity in an Extreme Mars Analog Setting: Poás Volcano, Costa Rica. ASTROBIOLOGY 2018; 18:923-933. [PMID: 29688767 PMCID: PMC6067093 DOI: 10.1089/ast.2017.1719] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The Poás volcano in Costa Rica has been studied as a Mars geochemical analog environment, since both the style of hydrothermal alteration present and the alteration mineralogy are consistent with Mars' relict hydrothermal systems. The site hosts an active volcano, with high-temperature fumaroles (up to 980°C) and an ultra-acidic lake. This lake, Laguna Caliente, is one of the most dynamic environments on Earth, with frequent phreatic eruptions, temperatures ranging from near-ambient to almost boiling, a pH range of -1 to 1.5, and a wide range of chemistries and redox potential. Martian acid-sulfate hydrothermal systems were likely similarly dynamic and equally challenging to life. The microbiology existing within Laguna Caliente was characterized for the first time, with sampling taking place in November, 2013. The diversity of the microbial community was surveyed via extraction of environmental DNA from fluid and sediment samples followed by Illumina sequencing of the 16S rRNA gene. The microbial diversity was limited to a single species of the bacterial genus Acidiphilium. This organism likely gets its energy from oxidation of reduced sulfur in the lake, including elemental sulfur. Given Mars' propensity for sulfur and acid-sulfate environments, this type of organism is of significant interest to the search for past or present life on the Red Planet. Key Words: Mars astrobiology-Acid-sulfate hydrothermal systems-Extremophiles-Acidic-High temperature-Acidiphilium bacteria. Astrobiology 18, 923-933.
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Affiliation(s)
- Brian M. Hynek
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA
- Department of Geological Sciences, University of Colorado, Boulder, Colorado, USA
- Address correspondence to:Brian M. HynekLaboratory for Atmospheric and Space PhysicsUniversity of Colorado3665 Discovery Dr.Boulder, CO 80303
| | - Karyn L. Rogers
- Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Monique Antunovich
- Department of Geological Sciences, University of Colorado, Boulder, Colorado, USA
| | - Geoffroy Avard
- OVSICORI, National University of Costa Rica, Heredia, Costa Rica
| | - Guillermo E. Alvarado
- Centro de Investigaciones Geológicas, Red Sismológica Nacional, Universidad de Costa Rica, Costa Rica
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76
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McMahon S, Bosak T, Grotzinger JP, Milliken RE, Summons RE, Daye M, Newman SA, Fraeman A, Williford KH, Briggs DEG. A Field Guide to Finding Fossils on Mars. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2018; 123:1012-1040. [PMID: 30034979 PMCID: PMC6049883 DOI: 10.1029/2017je005478] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/28/2018] [Accepted: 04/23/2018] [Indexed: 05/05/2023]
Abstract
The Martian surface is cold, dry, exposed to biologically harmful radiation and apparently barren today. Nevertheless, there is clear geological evidence for warmer, wetter intervals in the past that could have supported life at or near the surface. This evidence has motivated National Aeronautics and Space Administration and European Space Agency to prioritize the search for any remains or traces of organisms from early Mars in forthcoming missions. Informed by (1) stratigraphic, mineralogical and geochemical data collected by previous and current missions, (2) Earth's fossil record, and (3) experimental studies of organic decay and preservation, we here consider whether, how, and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early Mars. We conclude that Noachian-Hesperian Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits, especially where enriched in silica, currently represent the most promising and best understood astropaleontological targets. Siliceous sinters would also be an excellent target, but their presence on Mars awaits confirmation. More work is needed to improve our understanding of fossil preservation in the context of other environments specific to Mars, particularly within evaporative salts and pore/fracture-filling subsurface minerals.
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Affiliation(s)
- S. McMahon
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
- UK Centre for Astrobiology, School of Physics and AstronomyUniversity of EdinburghEdinburghUK
| | - T. Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - J. P. Grotzinger
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
| | - R. E. Milliken
- Department of Earth, Environmental and Planetary SciencesBrown UniversityProvidenceRIUSA
| | - R. E. Summons
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - M. Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - S. A. Newman
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - A. Fraeman
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. H. Williford
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. E. G. Briggs
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
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77
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Cabrol NA. The Coevolution of Life and Environment on Mars: An Ecosystem Perspective on the Robotic Exploration of Biosignatures. ASTROBIOLOGY 2018; 18:1-27. [PMID: 29252008 PMCID: PMC5779243 DOI: 10.1089/ast.2017.1756] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/27/2017] [Indexed: 05/09/2023]
Abstract
Earth's biological and environmental evolution are intertwined and inseparable. This coevolution has become a fundamental concept in astrobiology and is key to the search for life beyond our planet. In the case of Mars, whether a coevolution took place is unknown, but analyzing the factors at play shows the uniqueness of each planetary experiment regardless of similarities. Early Earth and early Mars shared traits. However, biological processes on Mars, if any, would have had to proceed within the distinctive context of an irreversible atmospheric collapse, greater climate variability, and specific planetary characteristics. In that, Mars is an important test bed for comparing the effects of a unique set of spatiotemporal changes on an Earth-like, yet different, planet. Many questions remain unanswered about Mars' early environment. Nevertheless, existing data sets provide a foundation for an intellectual framework where notional coevolution models can be explored. In this framework, the focus is shifted from planetary-scale habitability to the prospect of habitats, microbial ecotones, pathways to biological dispersal, biomass repositories, and their meaning for exploration. Critically, as we search for biosignatures, this focus demonstrates the importance of starting to think of early Mars as a biosphere and vigorously integrating an ecosystem approach to landing site selection and exploration. Key Words: Astrobiology-Biosignatures-Coevolution of Earth and life-Mars. Astrobiology 18, 1-27.
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78
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Zeng Z, Tice MM. Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation. ASTROBIOLOGY 2018; 18:28-36. [PMID: 29265883 DOI: 10.1089/ast.2016.1560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms. Key Words: Microbial iron reduction-Micropore-Electron transfer strategies-Microbial carbonate. Astrobiology 18, 28-36.
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Affiliation(s)
- Zhirui Zeng
- Department of Geology and Geophysics, Texas A&M University , College Station, Texas
| | - Michael M Tice
- Department of Geology and Geophysics, Texas A&M University , College Station, Texas
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79
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Hays L, Beaty D. Conference Report: Biosignature Preservation and Detection in Mars Analog Environments. ASTROBIOLOGY 2017; 17:1-2. [PMID: 28072548 DOI: 10.1089/ast.2016.1608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Conference on Biosignature Preservation and Detection in Mars Analog Environments held in May 2016 brought together scientists to discuss microbial biosignatures in Mars analog habitable environments. Five analog environments were discussed: (1) hydrothermal spring systems, (2) subaqueous environments, (3) subaerial environments, (4) subsurface environments, and (5) iron-rich systems. This paper details the major messages that resulted from the discussions and will be followed by a review paper that adds significant detail from the published literature and interpretations from the writing committee of the workshop for future research and application to astrobiological exploration missions. Key Words: Biosignature preservation-Biosignature detection-Mars analog environments-Conference report-Astrobiological exploration. Astrobiology 17, 1-2.
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Affiliation(s)
- Lindsay Hays
- Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - David Beaty
- Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
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