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Buckner DK, Anderson MJ, Wisnosky S, Alvarado W, Nuevo M, Williams AJ, Ricco AJ, Anamika, Debic S, Friend L, Hoac T, Jahnke L, Radosevich L, Williams R, Wilhelm MB. Quantifying Global Origin-Diagnostic Features and Patterns in Biotic and Abiotic Acyclic Lipids for Life Detection. ASTROBIOLOGY 2024; 24:1-35. [PMID: 38150549 DOI: 10.1089/ast.2023.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Lipids are a geologically robust class of organics ubiquitous to life as we know it. Lipid-like soluble organics are synthesized abiotically and have been identified in carbonaceous meteorites and on Mars. Ascertaining the origin of lipids on Mars would be a profound astrobiological achievement. We enumerate origin-diagnostic features and patterns in two acyclic lipid classes, fatty acids (i.e., carboxylic acids) and acyclic hydrocarbons, by collecting and analyzing molecular data reported in over 1500 samples from previously published studies of terrestrial and meteoritic organics. We identify 27 combined (15 for fatty acids, 12 for acyclic hydrocarbons) molecular patterns and structural features that can aid in distinguishing biotic from abiotic synthesis. Principal component analysis (PCA) demonstrates that multivariate analyses of molecular features (16 for fatty acids, 14 for acyclic hydrocarbons) can potentially indicate sample origin. Terrestrial lipids are dominated by longer straight-chain molecules (C4-C34 fatty acids, C14-C46 acyclic hydrocarbons), with predominance for specific branched and unsaturated isomers. Lipid-like meteoritic soluble organics are shorter, with random configurations. Organic solvent-extraction techniques are most commonly reported, motivating the design of our novel instrument, the Extractor for Chemical Analysis of Lipid Biomarkers in Regolith (ExCALiBR), which extracts lipids while preserving origin-diagnostic features that can indicate biogenicity.
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Affiliation(s)
- Denise K Buckner
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | - Morgan J Anderson
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Axient Corporation, Huntsville, Alabama, USA
| | - Sydney Wisnosky
- Axient Corporation, Huntsville, Alabama, USA
- Department of Biology, University of Miami, Coral Gables, Florida, USA
| | - Walter Alvarado
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Michel Nuevo
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | - Amy J Williams
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
| | - Antonio J Ricco
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Electrical Engineering-Integrated Circuits Laboratory, Stanford University, Stanford, California, USA
| | - Anamika
- Department of Space Studies, University of North Dakota, Grand Forks, North Dakota, USA
| | - Sara Debic
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Trinh Hoac
- Axient Corporation, Huntsville, Alabama, USA
| | - Linda Jahnke
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | | | - Ross Williams
- Civil & Environmental Engineering & Earth Sciences, Notre Dame University, Notre Dame, Indiana, USA
| | - Mary Beth Wilhelm
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
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Demaret L, Hutchinson IB, Eppe G, Malherbe C. Quantitative analysis of binary and ternary organo-mineral solid dispersions by Raman spectroscopy for robotic planetary exploration missions on Mars. Analyst 2021; 146:7306-7319. [PMID: 34755725 DOI: 10.1039/d1an01514a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The Mars 2020 and ExoMars 2022, rover-based missions are specifically dedicated to the search for evidence of life and will both utilise Raman spectrometers on the surface of Mars. Raman spectroscopy is indeed a valuable analytical technique for planetary exploration that enables in situ characterisation of rocks and soils collected directly from the surface or retrieved as cores and subsequently crushed when extracted from the subsurface with a drill. On Mars, the miniaturised spectrometers will interrogate ancient geological deposits, in order to try and identify hydrated or aqueously altered minerals and organic matter to assess the habitability of Mars. While the identification of relevant hydrous minerals and organic components is the primary analytical objective of the missions, quantifying their abundances would be of particular significance for interpreting past geological conditions (e.g. formation or alteration processes) and for ascertaining the putative presence of biosignatures. Therefore, we have developed quantitative models that enable the quantification of both mineral proportions from crushed mixtures of geological components and spiked mixtures containing organic analytes dispersed in mineral matrices. Based on data normalisation with appropriate standards (internal and external), we demonstrate that robust quantitative models can be (1) applied for solid dispersions of various complexities relevant to planetary exploration; and (2) applied to different Raman set-ups, including an instrument representative of the ExoMars Raman Laser Spectrometer. With important Raman-active minerals (calcite, gypsum, baryte, quartz), we demonstrate that using a correction factor Fϕ2/ϕ1, based on the ratio of apparent Raman scattering coefficients, the relative proportion of minerals in binary mixtures can be accurately determined. Regarding the organics, evaluated in clay-rich sediments (Fe-smectite) and crushed rocks of coarse-grained fraction (>100μm), we establish calibration curves in the concentration range 2-20 wt% for non-resonant compounds (L-cysteine, phthalic acid, adenine) and even lower (<1 wt%) for pre-resonant anthracene. Despite large levels of heterogeneity, the Raman analyses of these solid dispersions verify that quantitative Raman analyses can be performed in the context of robotic exploration studies.
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Affiliation(s)
- L Demaret
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, Liège, Belgium. .,Early Life Traces & Evolution Laboratory, UR Astrobiology, University of Liège, Liège, Belgium
| | - I B Hutchinson
- Department of Physics and Astronomy, University of Leicester, Leicester, UK
| | - G Eppe
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, Liège, Belgium.
| | - C Malherbe
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, Liège, Belgium. .,Early Life Traces & Evolution Laboratory, UR Astrobiology, University of Liège, Liège, Belgium.,Department of Physics and Astronomy, University of Leicester, Leicester, UK
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Chaddha AS, Sharma A, Singh NK. Clay minerals identification in rock varnish by XRD: A one-step reduction approach. MethodsX 2021; 8:101511. [PMID: 34754782 PMCID: PMC8563653 DOI: 10.1016/j.mex.2021.101511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/06/2021] [Indexed: 11/29/2022] Open
Abstract
Rock varnishes are known to be fine, dark, glossy submicron films found in deserts bare rock surfaces. The oxides and hydroxides of manganese and iron bind together the clay minerals present in the varnish layer. The processes of oxide-hydroxide accumulation at varnish sites are due to iron and manganese oxidizing bacteria which may require clay minerals for additional nutrition. Quantification and identification of clay minerals in this biofilm is needed to understand its formation. Past attempts to analyze the mineralogical composition of rock varnish have led to inconclusive results as varnish is a submicron thin layer composed of a complex mineral matrix. The elimination of non-crystalline cementing groups comprising of free iron oxides is a key step in the identification of many types of clay minerals, particularly in soil/sediment mineral studies.The Fe-Mn oxide-hydroxide coatings, acting as cementing materials, can be easily removed using a one-step reduction method employing Na2S2O4 at 70 °C, leading to separation of clay minerals. We have taken the lead from earlier reported Jackson (1958) method, wherein a combination of reagents was used such as sodium acetate, sodium citrate, hydrogen peroxide, sodium bicarbonate, and sodium dithionite for removing carbonate, organic carbon and Fe-Mn oxy-hydroxide coatings respectively from sediment grains to segregate individual grains from each other. Our modification helps in the unveiling of clay minerals from a solid substrate and reports the X-ray diffraction peaks, which are elsewise hard to detect and therefore earlier studies are inconclusive.
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Affiliation(s)
- Amritpal Singh Chaddha
- Birbal Sahni Institute of Palaeosciences, Lucknow-226007, India.,Department of Chemistry, University of Lucknow, Lucknow-226007, India
| | - Anupam Sharma
- Birbal Sahni Institute of Palaeosciences, Lucknow-226007, India
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