Astrobiology最新文献

{"title":"Solid-State Single-Molecule Sensing with the Electronic Life-Detection Instrument for Enceladus/Europa (ELIE).","authors":"Christopher E Carr, José L Ramírez-Colón, Daniel Duzdevich, Sam Lee, Masateru Taniguchi, Takahito Ohshiro, Yuki Komoto, Jason M Soderblom, M T Zuber","doi":"10.1089/ast.2022.0119","DOIUrl":"10.1089/ast.2022.0119","url":null,"abstract":"<p><p>Growing evidence of the potential habitability of Ocean Worlds across our solar system is motivating the advancement of technologies capable of detecting life as we know it-sharing a common ancestry or physicochemical origin with life on Earth-or don't know it, representing a distinct emergence of life different than our one known example. Here, we propose the Electronic Life-detection Instrument for Enceladus/Europa (ELIE), a solid-state single-molecule instrument payload that aims to search for life based on the detection of amino acids and informational polymers (IPs) at the parts per billion to trillion level. As a first proof-of-principle in a laboratory environment, we demonstrate the single-molecule detection of the amino acid L-proline at a 10 μM concentration in a compact system. Based on ELIE's solid-state quantum electronic tunneling sensing mechanism, we further propose the quantum property of the HOMO-LUMO gap (energy difference between a molecule's highest energy-occupied molecular orbital and lowest energy-unoccupied molecular orbital) as a novel metric to assess amino acid complexity. Finally, we assess the potential of ELIE to discriminate between abiotically and biotically derived α-amino acid abundance distributions to reduce the false positive risk for life detection. Nanogap technology can also be applied to the detection of nucleobases and short sequences of IPs such as, but not limited to, RNA and DNA. Future missions may utilize ELIE to target preserved biosignatures on the surface of Mars, extant life in its deep subsurface, or life or its biosignatures in a plume, surface, or subsurface of ice moons such as Enceladus or Europa. One-Sentence Summary: A solid-state nanogap can determine the abundance distribution of amino acids, detect nucleic acids, and shows potential for detecting life as we know it and life as we don't know it.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41101442","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":"Life Detection on Icy Moons Using Flow Cytometry and Exogenous Fluorescent Stains.","authors":"Matthew L Wallace,&nbsp;Nicholas Tallarida,&nbsp;Wayne W Schubert,&nbsp;James Lambert","doi":"10.1089/ast.2023.0016","DOIUrl":"10.1089/ast.2023.0016","url":null,"abstract":"<p><p>Flow cytometry is a potential technology for <i>in situ</i> life detection on icy moons (such as Enceladus and Europa) and on the polar ice caps of Mars. We developed a method for using flow cytometry to positively identify four classes of biomarkers using exogenous fluorescent stains: nucleic acids, proteins, carbohydrates, and lipids. We demonstrated the effectiveness of exogenous stains with six known organisms and known abiotic material and showed that the cytometer is easily able to distinguish between the known organisms and the known abiotic material using the exogenous stains. To simulate a life-detection experiment on an icy world lander, we used six natural samples with unknown biotic and abiotic content. We showed that flow cytometry can identify all four biomarkers using the exogenous stains and can separate the biotic material from the known abiotic material on scatter plots. Exogenous staining techniques would likely be used in conjunction with intrinsic fluorescence, clustering, and sorting for a more complete and capable life-detection instrument on an icy moon lander.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10160741","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 Catalytic Activity as a Method for Agnostic Life Detection.","authors":"Christos D Georgiou, Christopher McKay, Jean-Louis Reymond","doi":"10.1089/ast.2023.0022","DOIUrl":"10.1089/ast.2023.0022","url":null,"abstract":"<p><p>An ideal life detection instrument would have high sensitivity but be insensitive to abiotic processes and would be capable of detecting life with alternate molecular structures. In this study, we propose that catalytic activity can be the basis of a nearly ideal life detection instrument. There are several advantages to catalysis as an agnostic life detection method. Demonstrating catalysis does not necessarily require culturing/growing the alien life and in fact may persist even in dead biomass for some time, and the amplification by catalysis is large even by minute amounts of catalysts and, hence, can be readily detected against abiotic background rates. In specific, we propose a hydrolytic catalysis detection instrument that could detect activity in samples of extraterrestrial organic material from unknown life. The instrument uses chromogenic assay-based detection of various hydrolytic catalytic activities, which are matched to corresponding artificial substrates having the same, chromogenic (preferably fluorescent) upon release, group; D- and L-enantiomers of these substrates can be used to also answer the question whether unknown life is chiral. Since catalysis is a time-proportional product-concentration amplification process, hydrolytic catalytic activity can be measured on a sample of even a minute size, and with instruments based on, for example, optofluidic chip technology.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9901996","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":"Consumption of Hydrogen by Annihilation Reactions in Ultradense Hydrogen H(0) Contributed to Form a Hot and Dry Venus.","authors":"Leif Holmlid, Frans Olofson, Dan Gall","doi":"10.1089/ast.2022.0131","DOIUrl":"10.1089/ast.2022.0131","url":null,"abstract":"<p><p>When water vapor reacts with metals at temperatures of a few hundred kelvin, free hydrogen and metal oxides are formed. Iron is a common metal giving such reactions. Iron oxide together with a small amount of alkali metal as promoter is a good catalyst for forming ultradense hydrogen H(0) from the released hydrogen. Ultradense hydrogen is the densest form of condensed matter hydrogen. It can be formed easily at low pressure and is the densest material in the Solar System. Spontaneous and induced nuclear processes in H(0) create mesons (kaons, pions) in proton annihilation reactions. It is here agreed on that the great difference in the present conditions on Venus and Earth are caused by the initial difference in the temperatures of the planets due to their different distances from the Sun. This temperature difference means that, in warmer planetary environments such as on Venus, the iron + water steam → iron oxide + hydrogen reaction proceeded easily, meaning a consumption of water to give H(0) formation and release of nuclear energy by subsequent nuclear reactions in H(0). On the slightly cooler Earth, the iron + liquid water reaction was slower, and less water formed H(0). Thus, the water consumption and the heating due to nuclear reactions was smaller on Earth. The experiments proving that the mechanisms of forming H(0) and the details of the nuclear processes have been published. The more intense particle radiation from the nuclear processes in H(0) and the lack of water probably impeded formation of complex molecules and, thus, of life on planets like Venus. These processes in H(0) may, therefore, also imply a narrower zone of life in a planetary system than believed previously.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10616947/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41109350","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":"Origin of Homochirality in Amino Acids Induced by Lyman-α Irradiation in the Early Stage of the Milky Way.","authors":"Akimasa Sato, Mitsuo Shoji, Natsuki Watanabe, Mauro Boero, Yasuteru Shigeta, Masayuki Umemura","doi":"10.1089/ast.2022.0140","DOIUrl":"10.1089/ast.2022.0140","url":null,"abstract":"<p><p>The enantiomeric excess (ee) of l-form amino acids found in the Murchison meteorite poses some issues about the cosmic origin of their chirality. Circular dichroism (CD) spectra of amino acids in the far-ultraviolet (FUV) at around 6.8 eV (182 nm) indicate that the circularly polarized light can induce ee through photochemical reactions. Here, we resort to <i>ab initio</i> calculations to extract the CD spectra up to the vacuum-ultraviolet (VUV) region (∼11 eV), and we propose a novel equation to compute the ee applicable to a wider range of light frequency than what is available to date. This allows us to show that the strength of the induced ee (|ee|) in the 10 eV VUV region is comparable to the one in the 6.8 eV FUV region. This feature is common for some key amino acids (alanine, 2-aminobutyric acid, and valine). In space, intense Lyman-α (Lyα) light of 10.2 eV is emitted from star forming regions. This study provides a theoretical basis that Lyα emitter from an early starburst in the Milky Way plays a crucial role in initiating the ee of amino acids.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41103861","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":"A Comparative Study of Methods for Detecting Extraterrestrial Life in Exploration Missions to Mars and the Solar System II: Targeted Characteristics, Detection Techniques, and Their Combination for Survey, Detection, and Analysis.","authors":"Keigo Enya, Akihiko Yamagishi, Kensei Kobayashi, Yoshitaka Yoshimura, Elizabeth J Tasker","doi":"10.1089/ast.2022.0148","DOIUrl":"10.1089/ast.2022.0148","url":null,"abstract":"<p><p>We present a comparative study of the methods used in the search for extraterrestrial microorganism life, including a summary table where different life-detection techniques can be easily compared as an aid to mission and instrument design aimed at life detection. This is an extension of previous study, where detection techniques for a series of target characteristics and molecules that could constitute a positive life detection were evaluated. This comparison has been extended with a particular consideration to sources of false positives, the causes of negative detection, the results of detection techniques when presented regarding terrestrial life, and additional science objectives that could be achieved outside the primary aim of detecting life. These additions address both the scientific and programmatic side of exploration mission design, where a successful proposal must demonstrate probable outcomes and be able to return valuable results even if no life is found. The applicability of the life detection techniques is considered for Earth life, Earth-independent life (life emerging independently from that on Earth,) and Earth-kin life (sharing a common ancestor with life on Earth), and techniques effective in detecting Earth life should also be useful in the detection of Earth-kin life. However, their applicability is not guaranteed for Earth-independent life. As found in our previous study, there exists no realistic single detection method that can conclusively determine the discovery of extraterrestrial life, and no method is superior to all others. In this study, we further consider combinations of detection techniques and identify imaging as a valuable addition to molecule detection methods, even in cases where there is insufficient resolution to observe the detailed morphology of a microbial cell. The search for extraterrestrial life is further divided into a survey-and-detection and analysis-and-conclusion step. These steps benefit from different detection techniques, but imaging is necessary for both parts.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10616949/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41103208","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":"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":null,"pages":null},"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":"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":null,"pages":null},"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":"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":null,"pages":null},"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":"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":null,"pages":null},"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}