Astrobiology最新文献

{"title":"Inducing Homochirality Through Intermediary Catalytic Species: A Stochastic Approach.","authors":"Osmel Martín, Yoelsy Leyva, José Suárez-Lezcano, Yunierkis Pérez-Castillo, Yovani Marrero-Ponce","doi":"10.1089/ast.2023.0004","DOIUrl":"10.1089/ast.2023.0004","url":null,"abstract":"<p><p>A new chiral amplification mechanism based on a stochastic approach is proposed. The mechanism includes five different chemical species, an achiral substrate (A), two chiral forms (L, D), and two intermediary species (LA, DA). The process occurs within a small, semipermeable compartment that can be diffusively coupled with the outside environment. The study considers two alternative primary sources for chiral species within the compartment, one chemical and the other diffusive. As a remarkable fact, the chiral amplification process occurs due to stochastic fluctuations of an intermediary catalytic species (LA, DA) produced <i>in situ,</i> given the interaction of the chiral species with the achiral substrate. The net process includes two different steps: the synthesis of the catalyst (LA and DA) and the catalytic production of new chiral species from the substrate. Stochastic simulations show that proper parameterization can induce a robust chiral state within the compartment regardless of whether the system is open or closed. We also show how an increase in the non-catalytic production of chiral species tends to negatively impact the homochirality degree of the system. By its conception, the proposed mechanism suggests a deeper connection with how most biochemical processes occur in living beings, a fact that could open new avenues for studying this fascinating phenomenon.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"1083-1089"},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10128851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the Cytotoxicity of Mars-Relevant Minerals upon Abrasion.","authors":"Martin Kobek-Kjeldager Sigvartssøn,&nbsp;Ebbe Norskov Bak,&nbsp;Per Nørnberg,&nbsp;Svend J Knak Jensen,&nbsp;Jan Thøgersen,&nbsp;Mikkel Begnhøj,&nbsp;Kai Finster","doi":"10.1089/ast.2023.0015","DOIUrl":"10.1089/ast.2023.0015","url":null,"abstract":"<p><p>Since the Viking Labeled Release experiments were carried out on Mars in the 1970s, it has been evident that the martian surface regolith has a strong oxidizing capacity that can convert organic compounds into CO₂ and probably water. While H₂O₂ was suggested originally for being the oxidizing agent responsible for the outcome of the Viking experiments, recent analyses of the martian regolith by the Phoenix lander and by consecutive missions point toward radiation-mediated decomposition products of perchlorate salts as the primary oxidant. In a series of experiments, we have shown that abrasion and triboelectric charging of basalt by simulated saltation could be an additional way of activating regolith. We have also shown that abraded basalt with a chemical composition close to that of martian regolith is toxic to several bacterial species and thus may affect the habitability of the martian surface. In the present study, we investigated the effect of the quantitatively most important minerals (olivine, augite, and plagioclase) and iron oxides (hematite, magnetite, and maghemite) on the survival of bacterial cells to elucidate whether a specific mineral that constitutes basalt is responsible for our observations. We observed that suspensions of iron-containing minerals olivine and augite in phosphate-buffered saline (1 × PBS) significantly reduce the number of surviving cells of our model organism <i>Pseudomonas putida</i> after 24 h of incubation. In contrast, the iron-free mineral plagioclase showed no effect. We also observed that suspending abraded olivine and augite in 1 × PBS led to a dramatic increase in pH compared to the pH of 1 × PBS alone. The sudden increase in pH caused by the presence of these minerals may partly explain the observed cytotoxicity. The cytotoxic effect of augite could be relieved when a strong buffer (20 × PBS) was used. In contrast, olivine, despite the stronger buffer, maintained its cytotoxicity. Iron oxides <i>per se</i> have no negative effect on the survival of our test organism. Overall, our experiments confirm the cytotoxicity of basalt and show that no single constituent mineral of the basalt can account for its toxicity. We could show that abraded iron-containing minerals (olivine and augite) change the pH of water when brought into suspension and thereby could affect the habitability of martian regolith.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"1090-1098"},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10160738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic Biosignature Degradation in Hydrothermal and Serpentinizing Environments: Implications for Life Detection on Icy Moons and Mars.","authors":"Jonathan S W Tan,&nbsp;Tara L Salter,&nbsp;Jonathan S Watson,&nbsp;J Hunter Waite,&nbsp;Mark A Sephton","doi":"10.1089/ast.2022.0144","DOIUrl":"10.1089/ast.2022.0144","url":null,"abstract":"<p><p>Evidence of liquid water is a primary indicator of habitability on the icy moons in our outer solar system as well as on terrestrial planets such as Mars. If liquid water-containing environments host life, some of its organic remains can be fossilized and preserved as organic biosignatures. However, inorganic materials may also be present and water-assisted organic-inorganic reactions can transform the organic architecture of biological remains. Our understanding of the fate of these organic remains can be assisted by experimental simulations that monitor the chemical changes that occur in microbial organic matter due to the presence of water and minerals. We performed hydrothermal experiments at temperatures between 100°C and 300°C involving lipid-rich microbes and natural serpentinite mineral mixtures generated by the subaqueous hydrothermal alteration of ultramafic rock. The products reveal what the signals of life may look like when subjected to water-organic-inorganic reactions. Straight- and branched-chain lipids in unaltered samples are joined by cyclization and aromatization products in hydrothermally altered samples. Hydrothermal reactions produce distinct products that are not present in the starting materials, including small, single-ring, heteroatomic, and aromatic compounds such as indoles and phenols. Hydrothermal reactions in the presence of serpentinite minerals lead to significant reduction of these organic structures and their replacement by diketopiperazines (DKPs) and dihydropyrazines (DHPs), which may be compounds that are distinct to organic-inorganic reactions. Given that the precursors of DKPs and DHPs are normally lost during early diagenesis, the presence of these compounds can be an indicator of coexisting recent life and hydrothermal processing in the presence of minerals. However, laboratory experiments reveal that the formation and preservation of these compounds can only occur within a distinct temperature window. Our findings are relevant to life detection missions that aim to access hydrothermal and serpentinizing environments in the subsurfaces of icy moons and Mars.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"1045-1055"},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10264299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Are Large Sulfur Isotope Variations Biosignatures in an Ancient, Impact-Induced Hydrothermal Mars Analog?","authors":"Christopher J Tino,&nbsp;Eva E Stüeken,&nbsp;Gernot Arp,&nbsp;Michael Ernst Böttcher,&nbsp;Steven M Bates,&nbsp;Timothy W Lyons","doi":"10.1089/ast.2022.0114","DOIUrl":"10.1089/ast.2022.0114","url":null,"abstract":"<p><p>Discrepancies have emerged concerning the application of sulfur stable isotope ratios as a biosignature in impact crater paleolakes. The first <i>in situ</i> δ³⁴S data from Mars at Gale crater display a ∼75‰ range that has been attributed to an abiotic mechanism. Yet biogeochemical studies of ancient environments on Earth generally interpret δ³⁴S fractionations >21‰ as indicative of a biological origin, and studies of δ³⁴S at analog impact crater lakes on Earth have followed the same approach. We performed analyses (including δ³⁴S, total organic carbon wt%, and scanning electron microscope imaging) on multiple lithologies from the Nördlinger Ries impact crater, focusing on hydrothermally altered impact breccias and associated sedimentary lake-fill sequences to determine whether the δ³⁴S properties define a biosignature. The differences in δ³⁴S between the host lithologies may have resulted from thermochemical sulfate reduction, microbial sulfate reduction, hydrothermal equilibrium fractionation, or any combination thereof. Despite abundant samples and instrumental precision currently exclusive to Earth-bound analyses, assertions of biogenicity from δ³⁴S variations >21‰ at the Miocene Ries impact crater are tenuous. This discourages the use of δ³⁴S as a biosignature in similar environments without independent checks that include the full geologic, biogeochemical, and textural context, as well as a comprehensive acknowledgment of alternative hypotheses.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"1027-1044"},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10288936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jack Dwayne Farmer: April 18, 1947-February 22, 2023.","authors":"David J Des Marais,&nbsp;Maria C Farmer,&nbsp;Ariel D Anbar,&nbsp;Jonathan Zaloumis,&nbsp;Svetlana Shkolyar,&nbsp;Charlene Estrada,&nbsp;Sherry L Cady","doi":"10.1089/ast.2023.0044","DOIUrl":"https://doi.org/10.1089/ast.2023.0044","url":null,"abstract":"","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"921-925"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10167353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unavoidable Extinctions in Ecosystems of Extreme Isolation.","authors":"Eftychia Symeonidou,&nbsp;John Maxwell Halley","doi":"10.1089/ast.2022.0116","DOIUrl":"10.1089/ast.2022.0116","url":null,"abstract":"<p><p>Future systems of extreme isolation, including initiatives in space exploration, may require the services of onboard ecosystems. Biosphere 2, which ran between 1991 and 1993, aspired to mimic the earthly ecosystem and assess the ability of humans and other species to survive in a fully enclosed space. In this study, the data for plant species survival in the tropical rainforest sector from the first 2-year mission were studied through the prism of the neutral theory of biodiversity (NTB), which predicts how closed communities develop and how they lose species due to random demographic effects. Biosphere-2 lost species faster than a neutral process would predict. The specific reasons have been well documented, but the integrated approach of NTB offers new insights. It predicts that a closed ecological community must lose species and there is a specific time frame for this. To test it properly, the operation time of Biosphere-2 should have been at least 30 times greater. The new insights that NTB brings to the story of Biosphere 2 could be important for microcosm studies in general. A similar analysis suggests that the operation and testing time of other simulated ecosystems should also be increased.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"951-958"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10234500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman Spectroscopic and Microbial Study of Biofilms Hosted Gypsum Deposits in the Hypersaline Wetlands: Astrobiological Perspective.","authors":"Zach Diloreto,&nbsp;Mirza Shaharyar Ahmad,&nbsp;Hamad Al Saad Al-Kuwari,&nbsp;Fadhil Sadooni,&nbsp;Tomaso R R Bontognali,&nbsp;Maria Dittrich","doi":"10.1089/ast.2023.0003","DOIUrl":"10.1089/ast.2023.0003","url":null,"abstract":"<p><p>Gypsum (CaSO₄·2H₂O) has been identified at the surface of Mars, by both orbiters and rovers. Because gypsum mostly forms in the presence of liquid water as an essential element for sustaining microbial life and has a low porosity, which is ideal for preserving organic material, it is a promising target to look for signs of past microbial life. In this article, we studied organic matter preservation within gypsum that precipitates in a salt flat or a so-called coastal sabkha located in Qatar. Sabkha's ecosystem is considered a modern analog to evaporitic environments that may have existed on early Mars. We collected the sediment cores in the areas where gypsum is formed and performed DNA analysis to characterize the community of extremophilic microorganisms that is present at the site of gypsum formation. Subsequently, we applied Raman spectroscopy, a technique available on several rovers that are currently exploring Mars, to evaluate which organic molecules can be detected through the translucent gypsum crystals. We showed that organic material can be encapsulated into evaporitic gypsum and detected via Raman microscopy with simple, straightforward sample preparation. The molecular biology data proved useful for assessing to what extent complex Raman spectra can be linked to the original microbial community, dominated by <i>Halobacteria</i> and methanogenic archaea, providing a reference for a signal that may be detected on Mars.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"991-1005"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10261397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of UV and Calcium Perchlorates on Uracil Deposited on Strontium Fluoride Substrates at Mars Pressure and Temperature.","authors":"N Chaouche-Mechidal,&nbsp;F Stalport,&nbsp;E Caupos,&nbsp;E Mebold,&nbsp;C Azémard,&nbsp;C Szopa,&nbsp;P Coll,&nbsp;H Cottin","doi":"10.1089/ast.2022.0137","DOIUrl":"10.1089/ast.2022.0137","url":null,"abstract":"<p><p>Organic matter is actively searched on Mars with current and future space missions as it is a key to detecting potential biosignatures. Given the current harsh environmental conditions at the surface of Mars, many organic compounds might not be preserved over a long period as they are exposed to energetic radiation such as ultraviolet light, which is not filtered above 190 nm by the martian atmosphere. Moreover, the presence of strong oxidizing species in the regolith, such as perchlorate salts, might enhance the photodegradation of organic compounds of astrobiological interest. Because current space instruments analyze samples collected in the upper surface layer, it is necessary to investigate the stability of organic matter at the surface of Mars. Previous experimental studies have shown that uracil, a molecule relevant to astrobiology, is quickly photolyzed when exposed to UV radiation under the temperature and pressure conditions of the martian surface with an experimental quantum efficiency of photodecomposition (φ_exp) of 0.30 ± 0.26 molecule·photon^-1. Moreover, the photolysis of uracil leads to the formation of more stable photoproducts that were identified as uracil dimers. The present work aims to characterize the additional effect of calcium perchlorate detected on Mars on the degradation of uracil. Results show that the presence of calcium perchlorate enhances the photodecomposition of uracil with φ_exp = 12.3 ± 8.3 molecule·photon^-1. Although some of the photoproducts formed during these experiments are common to those formed from pure uracil only, the Fourier transformation infrared (FTIR) detection of previously unseen chemical functions such as alkyne C ≡ C or nitrile C ≡ N has shown that additional chemical species are formed in the presence of calcium perchlorate in the irradiated sample. This implies that the effect of calcium perchlorate on the photolysis of uracil is not only kinetic but also related to the nature of the photoproducts formed.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"959-978"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10177816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Earth to Mars: A Protocol for Characterizing Permafrost in the Context of Climate Change as an Analog for Extraplanetary Exploration.","authors":"Kimberley R Miner,&nbsp;Joseph Razzell Hollis,&nbsp;Charles E Miller,&nbsp;Kyle Uckert,&nbsp;Thomas A Douglas,&nbsp;Emily Cardarelli,&nbsp;Rachel Mackelprang","doi":"10.1089/ast.2022.0155","DOIUrl":"10.1089/ast.2022.0155","url":null,"abstract":"<p><p><b>Abstract</b> Permafrost is important from an exobiology and climate change perspective. It serves as an analog for extraplanetary exploration, and it threatens to emit globally significant amounts of greenhouse gases as it thaws due to climate change. Viable microbes survive in Earth's permafrost, slowly metabolizing and transforming organic matter through geologic time. Ancient permafrost microbial communities represent a crucial resource for gaining novel insights into survival strategies adopted by extremotolerant organisms in extraplanetary analogs. We present a proof-of-concept study on ∼22 Kya permafrost to determine the potential for coupling Raman and fluorescence biosignature detection technology from the NASA Mars Perseverance rover with microbial community characterization in frozen soils, which could be expanded to other Earth and off-Earth locations. Besides the well-known utility for biosignature detection and identification, our results indicate that spectral mapping of permafrost could be used to rapidly characterize organic carbon characteristics. Coupled with microbial community analyses, this method has the potential to enhance our understanding of carbon degradation and emissions in thawing permafrost. Further, spectroscopy can be accomplished <i>in situ</i> to mitigate sample transport challenges and in assessing and prioritizing frozen soils for further investigation. This method has broad-range applicability to understanding microbial communities and their associations with biosignatures and soil carbon and mineralogic characteristics relevant to climate science and astrobiology.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"1006-1018"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10510695/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10624384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Determination of the Spatial Distribution of Indigenous Lipid Biomarkers in an Immature Jurassic Sediment Using Time-of-Flight-Secondary Ion Mass Spectrometry.","authors":"M Joseph Pasterski,&nbsp;Matthias Lorenz,&nbsp;Anton V Ievlev,&nbsp;Raveendra C Wickramasinghe,&nbsp;Luke Hanley,&nbsp;Fabien Kenig","doi":"10.1089/ast.2022.0145","DOIUrl":"10.1089/ast.2022.0145","url":null,"abstract":"<p><p>The ability to detect and map lipids, including potential lipid biomarkers, within a sedimentary matrix using mass spectrometry (MS) imaging may be critical to determine whether potential lipids detected in samples returned from Mars are indigenous to Mars or are contaminants. Here, we use gas chromatography-mass spectrometry (GC-MS) and time-of-flight-secondary ion mass spectrometry (ToF-SIMS) datasets collected from an organic-rich, thermally immature Jurassic geologic sample to constrain MS imaging analysis of indigenous lipid biomarkers in geologic samples. GC-MS data show that the extractable fractions are dominated by C₂₇-C₃₀ steranes and sterenes as well as isorenieratene derivatives. ToF-SIMS spectra from organic matter-rich laminae contain a strong, spatially restricted signal for ions <i>m/z</i> 370.3, <i>m/z</i> 372.3, and <i>m/z</i> 386.3, which we assign to C₂₇ sterenes, cholestane (C₂₇), and 4- or 24-methyl steranes (C₂₈), respectively, as well as characteristic fragment ions of isorenieratene derivatives, including <i>m/z</i> 133.1, <i>m/z</i> 171.1, and <i>m/z</i> 237.1. We observed individual steroid spatial heterogeneity at the scale of tens to hundreds of microns. The fine-scale heterogeneity observed implies that indigenous lipid biomarkers concentrated within specific regions may be detectable via ToF-SIMS in samples with even low amounts of organic carbon, including in samples returned from Mars.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"23 9","pages":"936-950"},"PeriodicalIF":4.2,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10177996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}