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Vinberg M, McIntyre RS, Giraldi A, Coello K. Struggling Can Also Show on the Inside: Current Knowledge of the Impact of Childhood Maltreatment on Biomarkers in Mood Disorders. Neuropsychiatr Dis Treat 2024; 20:583-595. [PMID: 38496323 PMCID: PMC10944138 DOI: 10.2147/ndt.s383322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 03/05/2024] [Indexed: 03/19/2024] Open
Abstract
The link between childhood maltreatment and mood disorders is complex and involves multiple bio-psycho-social factors that affect multiple molecular pathways. The present narrative review aims to clarify the current understanding of the impact of childhood maltreatment on biomarkers in patients with mood disorders and their first-degree relatives. Neurotransmitters, such as serotonin, dopamine, norepinephrine, and hormones (eg the stress hormone cortisol), play a crucial role in regulating mood and emotion. Childhood maltreatment can alter and affect the levels and functioning of these neurotransmitters in the brain; further, childhood maltreatment can lead to structural and connectivity changes in the brain, hence contributing to the development of mood disorders and moderating illness presentation and modifying response to treatments. Childhood maltreatment information, therefore, appears mandatory in treatment planning and is a critical factor in therapeutic algorithms. Further research is needed to fully understand these pathways and develop new treatment modalities for individuals with mood disorders who have experienced childhood maltreatment and effective preventive interventions for individuals at risk of developing mood disorders.
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Affiliation(s)
- Maj Vinberg
- Mental Health Centre Northern Zealand, the Early Multimodular Prevention, and Intervention Research Institution (EMPIRI) – Mental Health Services CPH, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Roger S McIntyre
- Mood Disorders Psychopharmacology Unit, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Annamaria Giraldi
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Sexological Clinic, Mental Health Center Copenhagen, Copenhagen University Hospital, Copenhagen, Denmark
| | - Klara Coello
- Copenhagen Affective Disorder Research Centre (CADIC), Psychiatric Centre Copenhagen, Frederiksberg, Denmark
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Malas J, Russo DC, Bollengier O, Malaska MJ, Lopes RMC, Kenig F, Meyer-Dombard DR. Biological functions at high pressure: transcriptome response of Shewanella oneidensis MR-1 to hydrostatic pressure relevant to Titan and other icy ocean worlds. Front Microbiol 2024; 15:1293928. [PMID: 38414766 PMCID: PMC10896736 DOI: 10.3389/fmicb.2024.1293928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/25/2024] [Indexed: 02/29/2024] Open
Abstract
High hydrostatic pressure (HHP) is a key driver of life's evolution and diversification on Earth. Icy moons such as Titan, Europa, and Enceladus harbor potentially habitable high-pressure environments within their subsurface oceans. Titan, in particular, is modeled to have subsurface ocean pressures ≥ 150 MPa, which are above the highest pressures known to support life on Earth in natural ecosystems. Piezophiles are organisms that grow optimally at pressures higher than atmospheric (0.1 MPa) pressure and have specialized adaptations to the physical constraints of high-pressure environments - up to ~110 MPa at Challenger Deep, the highest pressure deep-sea habitat explored. While non-piezophilic microorganisms have been shown to survive short exposures at Titan relevant pressures, the mechanisms of their survival under such conditions remain largely unelucidated. To better understand these mechanisms, we have conducted a study of gene expression for Shewanella oneidensis MR-1 using a high-pressure experimental culturing system. MR-1 was subjected to short-term (15 min) and long-term (2 h) HHP of 158 MPa, a value consistent with pressures expected near the top of Titan's subsurface ocean. We show that MR-1 is metabolically active in situ at HHP and is capable of viable growth following 2 h exposure to 158 MPa, with minimal pressure training beforehand. We further find that MR-1 regulates 264 genes in response to short-term HHP, the majority of which are upregulated. Adaptations include upregulation of the genes argA, argB, argC, and argF involved in arginine biosynthesis and regulation of genes involved in membrane reconfiguration. MR-1 also utilizes stress response adaptations common to other environmental extremes such as genes encoding for the cold-shock protein CspG and antioxidant defense related genes. This study suggests Titan's ocean pressures may not limit life, as microorganisms could employ adaptations akin to those demonstrated by terrestrial organisms.
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Affiliation(s)
- Judy Malas
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Daniel C. Russo
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Olivier Bollengier
- Nantes Université, Univ Angers, Le Mans Université, CNRS, Laboratoire de Planétologie et Géosciences, LPG UMR 6112, Nantes, France
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Rosaly M. C. Lopes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Fabien Kenig
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - D'Arcy R. Meyer-Dombard
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
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Smith HB, Mathis C. Life detection in a universe of false positives: Can the Fatal Flaws of Exoplanet Biosignatures be Overcome Absent a Theory of Life? Bioessays 2023; 45:e2300050. [PMID: 37821360 DOI: 10.1002/bies.202300050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 09/24/2023] [Accepted: 09/27/2023] [Indexed: 10/13/2023]
Abstract
Astrobiology aims to determine the distribution and diversity of life in the universe. But as the word "biosignature" suggests, what will be detected is not life itself, but an observation implicating living systems. Our limited access to other worlds suggests this observation is more likely to reflect out-of-equilibrium gasses than a writhing octopus. Yet, anything short of a writhing octopus will raise skepticism about what has been detected. Resolving that skepticism requires a theory to delineate processes due to life and those due to abiotic mechanisms. This poses an existential question for life detection: How do astrobiologists plan to detect life on exoplanets via features shared between non-living and living systems? We argue that you cannot without an underlying theory of life. We illustrate this by analyzing the hypothetical detection of an "Earth 2.0" exoplanet. Without a theory of life, we argue the community should focus on identifying unambiguous features of life via four areas: examining life on Earth, building life in the lab, probing the solar system, and searching for technosignatures. Ultimately, we ask, what exactly do astrobiologists hope to learn by searching for life?
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Affiliation(s)
- Harrison B Smith
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Cole Mathis
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona, USA
- Santa Fe Institute, Santa Fe, New Mexico, USA
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Cleaves HJ, Hystad G, Prabhu A, Wong ML, Cody GD, Economon S, Hazen RM. A robust, agnostic molecular biosignature based on machine learning. Proc Natl Acad Sci U S A 2023; 120:e2307149120. [PMID: 37748080 PMCID: PMC10576141 DOI: 10.1073/pnas.2307149120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/17/2023] [Indexed: 09/27/2023] Open
Abstract
The search for definitive biosignatures-unambiguous markers of past or present life-is a central goal of paleobiology and astrobiology. We used pyrolysis-gas chromatography coupled to mass spectrometry to analyze chemically disparate samples, including living cells, geologically processed fossil organic material, carbon-rich meteorites, and laboratory-synthesized organic compounds and mixtures. Data from each sample were employed as training and test subsets for machine-learning methods, which resulted in a model that can identify the biogenicity of both contemporary and ancient geologically processed samples with ~90% accuracy. These machine-learning methods do not rely on precise compound identification: Rather, the relational aspects of chromatographic and mass peaks provide the needed information, which underscores this method's utility for detecting alien biology.
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Affiliation(s)
- H. James Cleaves
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Earth Life Science Institute, Tokyo Institute of Technology, Tokyo152-8550, Japan
- Blue Marble Space Institute for Science, Seattle, WA98104
| | - Grethe Hystad
- Department of Mathematics and Statistics, Purdue University Northwest, Hammond, IN46323
| | - Anirudh Prabhu
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
| | - Michael L. Wong
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Sagan Fellow, NASA Hubble Fellowship Program, Space Telescope Science Institute, Baltimore, MD21218
| | - George D. Cody
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
| | - Sophia Economon
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD21218
| | - Robert M. Hazen
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
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Li Y, Rochfort KD, Collins D, Grintzalis K. Development of Sensitive Methods for the Detection of Minimum Concentrations of DNA on Martian Soil Simulants. Life (Basel) 2023; 13:1999. [PMID: 37895382 PMCID: PMC10608431 DOI: 10.3390/life13101999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/29/2023] [Accepted: 09/29/2023] [Indexed: 10/29/2023] Open
Abstract
Several methods used for the quantification of DNA are based on UV absorbance or the fluorescence of complexes with intercalator dyes. Most of these intercalators are used in gels to visualize DNA and its structural integrity. Due to many extraterrestrial samples, such as meteorites or comets, which are likely to contain very small amounts of biological material, and because the ability to detect this material is crucial for understanding the origin and evolution of life in the universe, the development of assays that can detect DNA at low limits and withstand the rigors of space exploration is a pressing need in the field of astrobiology. In this study, we present a comparison of optimized protocols used for the fast and accurate quantification of DNA using common intercalator dyes. The sensitivity of assays exceeded that generated by any commercial kit and allowed for the accurate quantification of minimum concentrations of DNA. The methods were successful when applied to the detection and measurement of DNA spiked on soil samples. Furthermore, the impact of UV radiation as a harsh condition on the surface of Mars was assessed by DNA degradation and this was also confirmed by gel electrophoresis. Overall, the methods described provide economical, simple-step, and efficient approaches for the detection of DNA and can be used in future planetary exploration missions as tests used for the extraction of nucleic acid biosignatures.
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Affiliation(s)
- Yongda Li
- School of Biotechnology, Dublin City University, D09 Y5NO Dublin, Ireland; (Y.L.); (D.C.)
| | - Keith D. Rochfort
- School of Nursing, Psychotherapy, and Community Health, Dublin City University, D09 Y5NO Dublin, Ireland;
| | - David Collins
- School of Biotechnology, Dublin City University, D09 Y5NO Dublin, Ireland; (Y.L.); (D.C.)
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Sluka KA, Wager TD, Sutherland SP, Labosky PA, Balach T, Bayman EO, Berardi G, Brummett CM, Burns J, Buvanendran A, Caffo B, Calhoun VD, Clauw D, Chang A, Coffey CS, Dailey DL, Ecklund D, Fiehn O, Fisch KM, Frey Law LA, Harris RE, Harte SE, Howard TD, Jacobs J, Jacobs JM, Jepsen K, Johnston N, Langefeld CD, Laurent LC, Lenzi R, Lindquist MA, Lokshin A, Kahn A, McCarthy RJ, Olivier M, Porter L, Qian WJ, Sankar CA, Satterlee J, Swensen AC, Vance CG, Waljee J, Wandner LD, Williams DA, Wixson RL, Zhou XJ. Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures. Pain 2023; 164:1912-1926. [PMID: 37326643 PMCID: PMC10436361 DOI: 10.1097/j.pain.0000000000002938] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 06/17/2023]
Abstract
ABSTRACT Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention. Biomarkers are used to diagnose, track, and treat other diseases, but no validated clinical biomarkers exist yet for chronic pain. To address this problem, the National Institutes of Health Common Fund launched the Acute to Chronic Pain Signatures (A2CPS) program to evaluate candidate biomarkers, develop them into biosignatures, and discover novel biomarkers for chronification of pain after surgery. This article discusses candidate biomarkers identified by A2CPS for evaluation, including genomic, proteomic, metabolomic, lipidomic, neuroimaging, psychophysical, psychological, and behavioral measures. Acute to Chronic Pain Signatures will provide the most comprehensive investigation of biomarkers for the transition to chronic postsurgical pain undertaken to date. Data and analytic resources generatedby A2CPS will be shared with the scientific community in hopes that other investigators will extract valuable insights beyond A2CPS's initial findings. This article will review the identified biomarkers and rationale for including them, the current state of the science on biomarkers of the transition from acute to chronic pain, gaps in the literature, and how A2CPS will address these gaps.
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Affiliation(s)
- Kathleen A. Sluka
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Tor D. Wager
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH
| | - Stephani P. Sutherland
- Department of Biostatistics, Johns Hopkins Bloomberg Schools of Public Health, Baltimore, MD
| | - Patricia A. Labosky
- Office of Strategic Coordination, Division of Program Coordination, Planning and Strategic Initiatives, Office of the Director, National Institutes of Health, Bethesda, MD
| | - Tessa Balach
- Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago, Chicago, IL
| | - Emine O. Bayman
- Clinical Trials and Data Management Center, Department of Biostatistics, University of Iowa, Iowa City, IA
| | - Giovanni Berardi
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Chad M. Brummett
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI
| | - John Burns
- Division of Behavioral Sciences, Rush Medical College, Chicago, IL
| | | | - Brian Caffo
- Department of Biostatistics, Johns Hopkins Bloomberg Schools of Public Health, Baltimore, MD
| | - Vince D. Calhoun
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science (TReNDS), Georgia State, Georgia Tech, and Emory University, Atlanta, GA
| | - Daniel Clauw
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI
| | - Andrew Chang
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI
| | - Christopher S. Coffey
- Clinical Trials and Data Management Center, Department of Biostatistics, University of Iowa, Iowa City, IA
| | - Dana L. Dailey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Dixie Ecklund
- Clinical Trials and Data Management Center, Department of Biostatistics, University of Iowa, Iowa City, IA
| | - Oliver Fiehn
- University of California, Davis, Davis, CA, United States
| | - Kathleen M. Fisch
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Diego, San Diego, CA, United States
- Center for Computational Biology and Bioinformatics, University of California San Diego, San Diego, CA, United States
| | - Laura A. Frey Law
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Richard E. Harris
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI
| | - Steven E. Harte
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI
| | - Timothy D. Howard
- Department of Biochemistry, Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
- Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
| | - Joshua Jacobs
- Department of Orthopedic Surgery, Rush Medical College, CHicago, IL
| | - Jon M. Jacobs
- Environmental and Molecular Sciences Laboratory, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA
| | | | | | - Carl D. Langefeld
- Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
- Department of Biostatistics and Data Science, Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
| | - Louise C. Laurent
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Diego, San Diego, CA, United States
| | - Rebecca Lenzi
- Office of Strategic Coordination, Division of Program Coordination, Planning and Strategic Initiatives, Office of the Director, National Institutes of Health, Bethesda, MD
| | - Martin A. Lindquist
- Department of Biostatistics, Johns Hopkins Bloomberg Schools of Public Health, Baltimore, MD
| | | | - Ari Kahn
- Texas Advanced Computing Center, University of Texas, AUstin, TX
| | | | - Michael Olivier
- Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
- Department of Internal Medicine, Center for Precision Medicine, Wake Forest School of Medicine, Winstom-Salem, NC
| | - Linda Porter
- National Institute of Neurological Disorders and Stroke, Bethesda, MD
- Office of Pain Policy and Planning National Institutes of Health, Bethesda, MD
| | - Wei-Jun Qian
- Environmental and Molecular Sciences Laboratory, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA
| | - Cheryse A. Sankar
- National Institute of Neurological Disorders and Stroke, Bethesda, MD
| | | | - Adam C. Swensen
- Environmental and Molecular Sciences Laboratory, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA
| | - Carol G.T. Vance
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Jennifer Waljee
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI
| | - Laura D. Wandner
- National Institute of Neurological Disorders and Stroke, Bethesda, MD
| | - David A. Williams
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI
| | | | - Xiaohong Joe Zhou
- Center for MR Research and Departments of Radiology, Neurosurgery, and Bioengineering, University of Illinois College of Medicine at Chicago, Chicago, IL, United States
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Truong C, Bernard S, Le Pape P, Morin G, Baya C, Merrot P, Gorlas A, Guyot F. Production of carbon-containing pyrite spherules induced by hyperthermophilic Thermococcales: a biosignature? Front Microbiol 2023; 14:1145781. [PMID: 37303784 PMCID: PMC10248028 DOI: 10.3389/fmicb.2023.1145781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Thermococcales, a major order of hyperthermophilic archaea inhabiting iron- and sulfur-rich anaerobic parts of hydrothermal deep-sea vents, are known to induce the formation of iron phosphates, greigite (Fe3S4) and abundant quantities of pyrite (FeS2), including pyrite spherules. In the present study, we report the characterization of the sulfide and phosphate minerals produced in the presence of Thermococcales using X-ray diffraction, synchrotron-based X ray absorption spectroscopy and scanning and transmission electron microscopies. Mixed valence Fe(II)-Fe(III) phosphates are interpreted as resulting from the activity of Thermococcales controlling phosphorus-iron-sulfur dynamics. The pyrite spherules (absent in abiotic control) consist of an assemblage of ultra-small nanocrystals of a few ten nanometers in size, showing coherently diffracting domain sizes of few nanometers. The production of these spherules occurs via a sulfur redox swing from S0 to S-2 and then to S-1, involving a comproportionation of (-II) and (0) oxidation states of sulfur, as supported by S-XANES data. Importantly, these pyrite spherules sequester biogenic organic compounds in small but detectable quantities, possibly making them good biosignatures to be searched for in extreme environments.
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Affiliation(s)
- Chloé Truong
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Sylvain Bernard
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Pierre Le Pape
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Guillaume Morin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Camille Baya
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Pauline Merrot
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
| | - Aurore Gorlas
- CEA, CNRS, Institute for Integrative Biology of the Cell, Université Paris-Saclay, Gif-sur-Yvette, France
| | - François Guyot
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), MNHN, CNRS, IRD, Sorbonne Université, Paris, France
- Institut Universitaire de France (IUF), Paris, France
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8
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Garcia AK, Kędzior M, Taton A, Li M, Young JN, Kaçar B. Effects of RuBisCO and CO 2 concentration on cyanobacterial growth and carbon isotope fractionation. Geobiology 2023; 21:390-403. [PMID: 36602111 DOI: 10.1111/gbi.12543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/11/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
Carbon isotope biosignatures preserved in the Precambrian geologic record are primarily interpreted to reflect ancient cyanobacterial carbon fixation catalyzed by Form I RuBisCO enzymes. The average range of isotopic biosignatures generally follows that produced by extant cyanobacteria. However, this observation is difficult to reconcile with several environmental (e.g., temperature, pH, and CO2 concentrations), molecular, and physiological factors that likely would have differed during the Precambrian and can produce fractionation variability in contemporary organisms that meets or exceeds that observed in the geologic record. To test a specific range of genetic and environmental factors that may impact ancient carbon isotope biosignatures, we engineered a mutant strain of the model cyanobacterium Synechococcus elongatus PCC 7942 that overexpresses RuBisCO across varying atmospheric CO2 concentrations. We hypothesized that changes in RuBisCO expression would impact the net rates of intracellular CO2 fixation versus CO2 supply, and thus whole-cell carbon isotope discrimination. In particular, we investigated the impacts of RuBisCO overexpression under changing CO2 concentrations on both carbon isotope biosignatures and cyanobacterial physiology, including cell growth and oxygen evolution rates. We found that an increased pool of active RuBisCO does not significantly affect the 13 C/12 C isotopic discrimination (εp ) at all tested CO2 concentrations, yielding εp of ≈ 23‰ for both wild-type and mutant strains at elevated CO2 . We therefore suggest that expected variation in cyanobacterial RuBisCO expression patterns should not confound carbon isotope biosignature interpretation. A deeper understanding of environmental, evolutionary, and intracellular factors that impact cyanobacterial physiology and isotope discrimination is crucial for reconciling microbially driven carbon biosignatures with those preserved in the geologic record.
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Affiliation(s)
- Amanda K Garcia
- Department of Bacteriology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Mateusz Kędzior
- Department of Bacteriology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Arnaud Taton
- Division of Biological Sciences, University of California San Diego, La Jolla, California, USA
| | - Meng Li
- School of Oceanography, University of Washington, Seattle, Washington, USA
| | - Jodi N Young
- School of Oceanography, University of Washington, Seattle, Washington, USA
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin - Madison, Madison, Wisconsin, USA
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9
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Battistuzzi M, Cocola L, Claudi R, Pozzer AC, Segalla A, Simionato D, Morosinotto T, Poletto L, La Rocca N. Oxygenic photosynthetic responses of cyanobacteria exposed under an M-dwarf starlight simulator: Implications for exoplanet's habitability. Front Plant Sci 2023; 14:1070359. [PMID: 36824196 PMCID: PMC9941696 DOI: 10.3389/fpls.2023.1070359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
INTRODUCTION The search for life on distant exoplanets is expected to rely on atmospheric biosignatures detection, such as oxygen of biological origin. However, it is not demonstrated how much oxygenic photosynthesis, which on Earth depends on visible light, could work under spectral conditions simulating exoplanets orbiting the Habitable Zone of M-dwarf stars, which have low light emission in the visible and high light emission in the far-red/near-infrared. By utilizing cyanobacteria, the first organisms to evolve oxygenic photosynthesis on our planet, and a starlight simulator capable of accurately reproducing the emission spectrum of an M-dwarf in the range 350-900 nm, we could answer this question. METHODS We performed experiments with the cyanobacterium Chlorogloeopsis fritschii PCC6912, capable of Far-Red Light Photoacclimation (FaRLiP), which allows the strain to harvest far-red in addition to visible light for photosynthesis, and Synechocystis sp. PCC6803, a species unable to perform this photoacclimation, comparing their responses when exposed to three simulated light spectra: M-dwarf, solar and far-red. We analysed growth and photosynthetic acclimation features in terms of pigment composition and photosystems organization. Finally, we determined the oxygen production of the strains directly exposed to the different spectra. RESULTS Both cyanobacteria were shown to grow and photosynthesize similarly under M-dwarf and solar light conditions: Synechocystis sp. by utilizing the few photons in the visible, C. fritschii by harvesting both visible and far-red light, activating the FaRLiP response. DISCUSSION Our results experimentally show that an M-dwarf light spectrum could support a biological oxygen production similar to that in solar light at the tested light intensities, suggesting the possibility to discover such atmospheric biosignatures on those exoplanets if other boundary conditions are met.
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Affiliation(s)
- Mariano Battistuzzi
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
| | - Lorenzo Cocola
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), Padua, Italy
| | - Riccardo Claudi
- National Institute for Astrophysics, Astronomical Observatory of Padua (INAF-OAPD), Padua, Italy
| | - Anna Caterina Pozzer
- Department of Biology, University of Padua, Padua, Italy
- National Institute for Astrophysics, Astronomical Observatory of Padua (INAF-OAPD), Padua, Italy
| | - Anna Segalla
- Department of Biology, University of Padua, Padua, Italy
| | | | - Tomas Morosinotto
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
| | - Luca Poletto
- National Council of Research of Italy, Institute for Photonics and Nanotechnologies (CNR-IFN), Padua, Italy
| | - Nicoletta La Rocca
- Department of Biology, University of Padua, Padua, Italy
- Center for Space Studies and Activities (CISAS), University of Padua, Padua, Italy
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10
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Salter TL, Watson JS, Waite JH, Sephton MA. Hydrothermal Processing of Microorganisms: Mass Spectral Signals of Degraded Biosignatures for Life Detection on Icy Moons. ACS Earth Space Chem 2022; 6:2508-2518. [PMID: 36303715 PMCID: PMC9589906 DOI: 10.1021/acsearthspacechem.2c00213] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/30/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Life detection missions to the outer solar system are concentrating on the icy moons of Jupiter and Saturn and their inferred subsurface oceans. Access to evidence of habitability, and possibly even life, is facilitated by the ejection of subsurface material in plumes and outgassing fissures. Orbiting spacecraft can intersect the plume material or detect past sputtered remnants of outgassed products and analyze the contents using instruments such as mass spectrometers. Hydrothermalism has been proposed for the subsurface environments of icy moons, and the organic remains of any associated life would be expected to suffer some degradation through hydrothermalism, radiolysis, or spacecraft flyby impact fragmentation. Hydrothermalism is treated here for the first time in the context of the Europa Clipper mission. To assess the influence of hydrothermalism on the ability of orbiting mass spectrometers to detect degrading signals of life, we have subjected Earth microorganisms to laboratory hydrothermal processing. The processed microorganism samples were then analyzed using gas chromatography-mass spectrometry (GC-MS), and mass spectra were generated. Certain compound classes, such as carbohydrates and proteins, are significantly altered by hydrothermal processing, resulting in small one-ring and two-ring aromatic compounds such as indoles and phenols. However, lipid fragments, such as fatty acids, retain their fidelity, and their provenance is easily recognized as biological in origin. Our data indicate that mass spectrometry measurements in the plumes of icy moons, using instruments such as the MAss Spectrometer for Planetary Exploration (MASPEX) onboard the upcoming Europa Clipper mission, can reveal the presence of life even after significant degradation by hydrothermal processing has taken place.
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Affiliation(s)
- Tara L. Salter
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jonathan S. Watson
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - J. Hunter Waite
- Space
Science and Engineering Division, Southwest
Research Institute, San Antonio, Texas 78238, United States
| | - Mark A. Sephton
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
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11
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Kędzior M, Garcia AK, Li M, Taton A, Adam ZR, Young JN, Kaçar B. Resurrected Rubisco suggests uniform carbon isotope signatures over geologic time. Cell Rep 2022; 39:110726. [PMID: 35476992 DOI: 10.1016/j.celrep.2022.110726] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 02/26/2022] [Accepted: 03/30/2022] [Indexed: 11/30/2022] Open
Abstract
The earliest geochemical indicators of microbes-and the enzymes that powered them-extend back ∼3.8 Ga on Earth. Paleobiologists often attempt to understand these indicators by assuming that the behaviors of extant microbes and enzymes are uniform with those of their predecessors. This consistency in behavior seems at odds with our understanding of the inherent variability of living systems. Here, we examine whether a uniformitarian assumption for an enzyme thought to generate carbon isotope indicators of biological activity, RuBisCO, can be corroborated by independently studying the history of changes recorded within RuBisCO's genetic sequences. We resurrected a Precambrian-age RuBisCO by engineering its ancient DNA inside a cyanobacterium genome and measured the engineered organism's fitness and carbon-isotope-discrimination profile. Results indicate that Precambrian uniformitarian assumptions may be warranted but with important caveats. Experimental studies illuminating early innovations are crucial to explore the molecular foundations of life's earliest traces.
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Affiliation(s)
- Mateusz Kędzior
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Amanda K Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Meng Li
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Arnaud Taton
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zachary R Adam
- NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Geosciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jodi N Young
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; NASA Center for Early Life and Evolution, University of Wisconsin-Madison, Madison, WI 53706, USA.
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12
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Thompson MA, Krissansen-Totton J, Wogan N, Telus M, Fortney JJ. The case and context for atmospheric methane as an exoplanet biosignature. Proc Natl Acad Sci U S A 2022; 119:e2117933119. [PMID: 35353627 DOI: 10.1073/pnas.2117933119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Astronomers will soon begin searching for biosignatures, atmospheric gases or surface features produced by life, on potentially habitable planets. Since methane is the only biosignature that the James Webb Space Telescope could readily detect in terrestrial atmospheres, it is imperative to understand methane biosignatures to contextualize these upcoming observations. We explore the necessary planetary context for methane to be a persuasive biosignature and assess whether, and in what planetary environments, abiotic sources of methane could result in false-positive scenarios. With these results, we provide a tentative framework for assessing methane biosignatures. If life is abundant in the universe, then with the correct planetary context, atmospheric methane may be the first detectable indication of life beyond Earth. Methane has been proposed as an exoplanet biosignature. Imminent observations with the James Webb Space Telescope may enable methane detections on potentially habitable exoplanets, so it is essential to assess in what planetary contexts methane is a compelling biosignature. Methane’s short photochemical lifetime in terrestrial planet atmospheres implies that abundant methane requires large replenishment fluxes. While methane can be produced by a variety of abiotic mechanisms such as outgassing, serpentinizing reactions, and impacts, we argue that—in contrast to an Earth-like biosphere—known abiotic processes cannot easily generate atmospheres rich in CH4 and CO2 with limited CO due to the strong redox disequilibrium between CH4 and CO2. Methane is thus more likely to be biogenic for planets with 1) a terrestrial bulk density, high mean-molecular-weight and anoxic atmosphere, and an old host star; 2) an abundance of CH4 that implies surface fluxes exceeding what could be supplied by abiotic processes; and 3) atmospheric CO2 with comparatively little CO.
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13
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Wiemann J, Briggs DEG. Raman spectroscopy is a powerful tool in molecular paleobiology: An analytical response to Alleon et al. (https://doi.org/10.1002/bies.202000295). Bioessays 2022; 44:e2100070. [PMID: 34993976 DOI: 10.1002/bies.202100070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 01/08/2023]
Abstract
A recent article argued that signals from conventional Raman spectroscopy of organic materials are overwhelmed by edge filter and fluorescence artefacts. The article targeted a subset of Raman spectroscopic investigations of fossil and modern organisms and has implications for the utility of conventional Raman spectroscopy in comparative tissue analytics. The inferences were based on circular reasoning centered around the unconventional analysis of spectra from just two samples, one modern, and one fossil. We validated the disputed signals with in situ Fourier-Transform Infrared (FT-IR) Spectroscopy and through replication with different lasers, filters, and operators in independent laboratories. Our Raman system employs a holographic notch filter which is not affected by edge filter or other artefacts. Multiple lines of evidence confirm that conventional Raman spectra of fossils contain biologically and geologically meaningful information. Statistical analyses of large Raman and FT-IR spectral data sets reveal patterns in fossil composition and yield valuable insights into the history of life.
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Affiliation(s)
- Jasmina Wiemann
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA.,Dinosaur Institute, Natural History Museum of LA County, Los Angeles, California, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Yale Peabody Museum of Natural History, New Haven, Connecticut, USA
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14
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Michaelian K, Cano Mateo RE. A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems. Entropy (Basel) 2022; 24:e24010076. [PMID: 35052103 PMCID: PMC8774895 DOI: 10.3390/e24010076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/22/2021] [Accepted: 12/29/2021] [Indexed: 02/04/2023]
Abstract
Through a modern derivation of Planck’s formula for the entropy of an arbitrary beam of photons, we derive a general expression for entropy production due to the irreversible process of the absorption of an arbitrary incident photon spectrum in material and its dissipation into an infrared-shifted grey-body emitted spectrum, with the rest being reflected or transmitted. Employing the framework of Classical Irreversible Thermodynamic theory, we define the generalized thermodynamic flow as the flow of photons from the incident beam into the material and the generalized thermodynamic force is, then, the entropy production divided by the photon flow, which is the entropy production per unit photon at a given wavelength. We compare the entropy production of different inorganic and organic materials (water, desert, leaves and forests) under sunlight and show that organic materials are the greater entropy-producing materials. Intriguingly, plant and phytoplankton pigments (including chlorophyll) reach peak absorption exactly where entropy production through photon dissipation is maximal for our solar spectrum 430<λ<550 nm, while photosynthetic efficiency is maximal between 600 and 700 nm. These results suggest that the evolution of pigments, plants and ecosystems has been towards optimizing entropy production, rather than photosynthesis. We propose using the wavelength dependence of global entropy production as a biosignature for discovering life on planets of other stars.
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Affiliation(s)
- Karo Michaelian
- Department of Nuclear Physics and Application of Radiation, Instituto de Física, Universidad Nacional Autónoma de México, Cto. de la Investigación Científica, Cuidad Universitaria, Mexico City C.P. 04510, Mexico
- Correspondence:
| | - Ramón Eduardo Cano Mateo
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Cto. de la Investigación Científica, Cuidad Universitaria, Mexico City C.P. 04510, Mexico;
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15
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Guttenberg N, Chen H, Mochizuki T, Cleaves HJ 2nd. Classification of the Biogenicity of Complex Organic Mixtures for the Detection of Extraterrestrial Life. Life (Basel) 2021; 11:234. [PMID: 33809046 DOI: 10.3390/life11030234] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 11/17/2022] Open
Abstract
Searching for life in the Universe depends on unambiguously distinguishing biological features from background signals, which could take the form of chemical, morphological, or spectral signatures. The discovery and direct measurement of organic compounds unambiguously indicative of extraterrestrial (ET) life is a major goal of Solar System exploration. Biology processes matter and energy differently from abiological systems, and materials produced by biological systems may become enriched in planetary environments where biology is operative. However, ET biology might be composed of different components than terrestrial life. As ET sample return is difficult, in situ methods for identifying biology will be useful. Mass spectrometry (MS) is a potentially versatile life detection technique, which will be used to analyze numerous Solar System environments in the near future. We show here that simple algorithmic analysis of MS data from abiotic synthesis (natural and synthetic), microbial cells, and thermally processed biological materials (lab-grown organisms and petroleum) easily identifies relational organic compound distributions that distinguish pristine and aged biological and abiological materials, which likely can be attributed to the types of compounds these processes produce, as well as how they are formed and decompose. To our knowledge this is the first comprehensive demonstration of the utility of this analytical technique for the detection of biology. This method is independent of the detection of particular masses or molecular species samples may contain. This suggests a general method to agnostically detect evidence of biology using MS given a sufficiently strong signal in which the majority of the material in a sample has either a biological or abiological origin. Such metrics are also likely to be useful for studies of possible emergent living phenomena, and paleobiological samples.
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16
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Milojevic T, Kish A, Yamagishi A. Editorial: Astrobiology at the Interface: Interactions Between Biospheres, Geospheres, Hydrospheres and Atmospheres Under Planetary Conditions. Front Microbiol 2021; 12:629961. [PMID: 33643257 PMCID: PMC7906982 DOI: 10.3389/fmicb.2021.629961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 01/26/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tetyana Milojevic
- Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | | | - Akihiko Yamagishi
- Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
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17
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Chendi BH, Snyders CI, Tonby K, Jenum S, Kidd M, Walzl G, Chegou NN, Dyrhol-Riise AM. A Plasma 5-Marker Host Biosignature Identifies Tuberculosis in High and Low Endemic Countries. Front Immunol 2021; 12:608846. [PMID: 33732236 PMCID: PMC7958880 DOI: 10.3389/fimmu.2021.608846] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/03/2021] [Indexed: 01/06/2023] Open
Abstract
Background: Several host inflammatory markers have been proposed as biomarkers for diagnosis and treatment response in Tuberculosis (TB), but few studies compare their utility in different demographic, ethnic, and TB endemic settings. Methods: Fifty-four host biomarkers were evaluated in plasma samples obtained from presumed TB cases recruited at the Oslo University Hospital in Norway, and a health center in Cape Town, South Africa. Based on clinical and laboratory assessments, participants were classified as having TB or other respiratory diseases (ORD). The concentrations of biomarkers were analyzed using the Luminex multiplex platform. Results: Out of 185 study participants from both study sites, 107 (58%) had TB, and 78 (42%) ORD. Multiple host markers showed diagnostic potential in both the Norwegian and South African cohorts, with I-309 as the most accurate single marker irrespective of geographical setting. Although study site-specific biosignatures had high accuracy for TB, a site-independent 5-marker biosignature (G-CSF, C3b/iC3b, procalcitonin, IP-10, PDGF-BB) was identified diagnosing TB with a sensitivity of 72.7% (95% CI, 49.8–82.3) and specificity of 90.5% (95% CI, 69.6–98.8) irrespective of geographical site. Conclusion: A 5-marker host plasma biosignature has diagnostic potential for TB disease irrespective of TB setting and should be further explored in larger cohorts.
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Affiliation(s)
- Bih H Chendi
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Division of Molecular Biology and Human Genetics, Department of Science and Technology-National Research Foundation (DST-NRF) Centre of Excellence for Biomedical Tuberculosis Research, Faculty of Medicine and Health Sciences, South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
| | - Candice I Snyders
- Division of Molecular Biology and Human Genetics, Department of Science and Technology-National Research Foundation (DST-NRF) Centre of Excellence for Biomedical Tuberculosis Research, Faculty of Medicine and Health Sciences, South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
| | - Kristian Tonby
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway
| | - Synne Jenum
- Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway
| | - Martin Kidd
- Department of Statistics and Actuarial Sciences, Centre for Statistical Consultation, Stellenbosch University, Cape Town, South Africa
| | - Gerhard Walzl
- Division of Molecular Biology and Human Genetics, Department of Science and Technology-National Research Foundation (DST-NRF) Centre of Excellence for Biomedical Tuberculosis Research, Faculty of Medicine and Health Sciences, South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
| | - Novel N Chegou
- Division of Molecular Biology and Human Genetics, Department of Science and Technology-National Research Foundation (DST-NRF) Centre of Excellence for Biomedical Tuberculosis Research, Faculty of Medicine and Health Sciences, South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
| | - Anne M Dyrhol-Riise
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway
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18
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Gangidine A, Walter MR, Havig JR, Jones C, Sturmer DM, Czaja AD. Trace Element Concentrations Associated with Mid-Paleozoic Microfossils as Biosignatures to Aid in the Search for Life. Life (Basel) 2021; 11:142. [PMID: 33668639 DOI: 10.3390/life11020142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 02/03/2021] [Accepted: 02/09/2021] [Indexed: 12/29/2022] Open
Abstract
Identifying microbial fossils in the rock record is a difficult task because they are often simple in morphology and can be mimicked by non-biological structures. Biosignatures are essential for identifying putative fossils as being definitively biological in origin, but are often lacking due to geologic effects which can obscure or erase such signs. As such, there is a need for robust biosignature identification techniques. Here we show new evidence for the application of trace elements as biosignatures in microfossils. We found elevated concentrations of magnesium, aluminum, manganese, iron, and strontium colocalized with carbon and sulfur in microfossils from Drummond Basin, a mid-Paleozoic hot spring deposit in Australia. Our results also suggest that trace element sequestrations from modern hot spring deposits persist through substantial host rock alteration. Because some of the oldest fossils on Earth are found in hot spring deposits and ancient hot spring deposits are also thought to occur on Mars, this biosignature technique may be utilized as a valuable tool to aid in the search for extraterrestrial life.
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19
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Alleon J, Montagnac G, Reynard B, Brulé T, Thoury M, Gueriau P. Pushing Raman spectroscopy over the edge: purported signatures of organic molecules in fossil animals are instrumental artefacts. Bioessays 2021; 43:e2000295. [PMID: 33543495 DOI: 10.1002/bies.202000295] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/22/2020] [Accepted: 01/12/2021] [Indexed: 11/07/2022]
Abstract
Widespread preservation of fossilized biomolecules in many fossil animals has recently been reported in six studies, based on Raman microspectroscopy. Here, we show that the putative Raman signatures of organic compounds in these fossils are actually instrumental artefacts resulting from intense background luminescence. Raman spectroscopy is based on the detection of photons scattered inelastically by matter upon its interaction with a laser beam. For many natural materials, this interaction also generates a luminescence signal that is often orders of magnitude more intense than the light produced by Raman scattering. Such luminescence, coupled with the transmission properties of the spectrometer, induced quasi-periodic ripples in the measured spectra that have been incorrectly interpreted as Raman signatures of organic molecules. Although several analytical strategies have been developed to overcome this common issue, Raman microspectroscopy as used in the studies questioned here cannot be used to identify fossil biomolecules.
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Affiliation(s)
- Julien Alleon
- Institute of Earth Sciences, University of Lausanne, Géopolis, Lausanne, CH-1015, Switzerland
| | - Gilles Montagnac
- Université de Lyon, ENS de Lyon, Université Lyon 1, CNRS, LGL-TPE, Lyon, F-69007, France
| | - Bruno Reynard
- Université de Lyon, ENS de Lyon, Université Lyon 1, CNRS, LGL-TPE, Lyon, F-69007, France
| | | | - Mathieu Thoury
- Universitè Paris-Saclay, CNRS, ministère de la Culture, UVSQ, MNHN, Institut photonique d'analyse non-destructive européen des matériaux anciens, Saint-Aubin, 91192, France
| | - Pierre Gueriau
- Institute of Earth Sciences, University of Lausanne, Géopolis, Lausanne, CH-1015, Switzerland
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20
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Kok VC, Yu CC, Salvador JA. Editorial: Head & Neck Cancer and Esophageal Cancer: From Biosignatures to Therapeutics. Front Oncol 2021; 11:666103. [PMID: 33816319 PMCID: PMC8017309 DOI: 10.3389/fonc.2021.666103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 03/02/2021] [Indexed: 02/05/2023] Open
Affiliation(s)
- Victor C. Kok
- Division of Medical Oncology, Kuang Tien General Hospital Cancer Center, Taichung, Taiwan
- Department of Bioinformatics and Medical Engineering, Asia University Taiwan, Taichung, Taiwan
- *Correspondence: Victor C. Kok,
| | - Cheng-Chia Yu
- Institute of Oral Sciences, Chung Shan Medical University, Taichung, Taiwan
- School of Dentistry, Chung Shan Medical University, Taichung, Taiwan
| | - Jorge A.R. Salvador
- Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde—Azinhaga de Santa Comba, Coimbra, Portugal
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21
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Abstract
One of the major goals for astronomy in the next decades is the remote search for biosignatures (i.e., the spectroscopic evidence of biological activity) in exoplanets. Here we adopt a Bayesian statistical framework to discuss the implications of such future searches, both in the case when life is detected and when no definite evidence is found. We show that even a single detection of biosignatures in the vicinity of our stellar system, in a survey of similar size to what will be obtainable in the next 2 decades, would affect significantly our prior belief on the frequency of life in the universe, even starting from a neutral or pessimistic stance. In particular, after such discovery, an initially agnostic observer would be led to conclude that there are more than [Formula: see text] inhabited planets in the galaxy with a probability exceeding 95%. However, this conclusion would be somewhat weakened by the viability of transfer of biological material over interstellar distances, as in panspermia scenarios. Conversely, the lack of significant evidence of biosignatures would have little effect, leaving the assessment of the abundance of life in the galaxy still largely undetermined.
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22
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White RA, Visscher PT, Burns BP. Between a Rock and a Soft Place: The Role of Viruses in Lithification of Modern Microbial Mats. Trends Microbiol 2020; 29:204-213. [PMID: 32654857 DOI: 10.1016/j.tim.2020.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/07/2020] [Accepted: 06/16/2020] [Indexed: 12/22/2022]
Abstract
Stromatolites are geobiological systems formed by complex microbial communities, and fossilized stromatolites provide a record of some of the oldest life on Earth. Microbial mats are precursors of extant stromatolites; however, the mechanisms of transition from mat to stromatolite are controversial and are still not well understood. To fully recognize the profound impact that these ecosystems have had on the evolution of the biosphere requires an understanding of modern lithification mechanisms and how they relate to the geological record. We propose here viral mechanisms in carbonate precipitation, leading to stromatolite formation, whereby viruses directly or indirectly impact microbial metabolisms that govern the transition from microbial mat to stromatolite. Finding a tangible link between host-virus interactions and changes in biogeochemical processes will provide tools to interpret mineral biosignatures through geologic time, including those on Earth and beyond.
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Affiliation(s)
- Richard Allen White
- Plant Pathology, Washington State University, Pullman, WA, USA; Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia; RAW Molecular Systems (RMS) LLC, Spokane, WA, USA
| | - Pieter T Visscher
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia; Departments of Marine Sciences and Geosciences, University of Connecticut, CT, USA; Biogeosciences, the Université de Bourgogne Franche-Comté, Dijon, France
| | - Brendan P Burns
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia; School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia.
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23
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Popall RM, Bolhuis H, Muyzer G, Sánchez-Román M. Stromatolites as Biosignatures of Atmospheric Oxygenation: Carbonate Biomineralization and UV-C Resilience in a Geitlerinema sp. - Dominated Culture. Front Microbiol 2020; 11:948. [PMID: 32508777 PMCID: PMC7248245 DOI: 10.3389/fmicb.2020.00948] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 04/21/2020] [Indexed: 11/13/2022] Open
Abstract
Modern stromatolites are key to the record of past microbial activity preserved in fossil carbonate deposits. Mono-phototrophic cultures dominated by the cyanobacterium Geitlerinema sp. were obtained from a laboratory-maintained, low magnesium-calcite stromatolite originating from Lagoa Vermelha, Brazil. This lagoonal system has been described as a Precambrian analog, illustrating a period of photosynthetically induced atmospheric oxygenation, which created a global sanctuary from shortwave solar radiation and enabled the evolution of modern life on Earth. The enrichment cultures precipitate carbonates in minimal media, suggesting that cyanobacterial photosynthesis and extracellular polymeric substance production may be crucial in the mineralization of the studied stromatolite. We further show that Geitlerinema sp. can build and maintain filamentous mats under long-term UV-C exposure. Our results suggest that present day stromatolites dominated by cyanobacteria may be interpreted as biosignatures of atmospheric oxygenation and have implications for the search for putative biological traces on Mars.
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Affiliation(s)
- Rabja M. Popall
- Earth Sciences Department, Faculty of Science, Vrije Universiteit, Amsterdam, Netherlands
| | - Henk Bolhuis
- Marine Microbiology & Biogeochemistry Department, Royal Netherlands Institute for Sea Research, Utrecht University, Den Hoorn, Netherlands
| | - Gerard Muyzer
- Microbial Systems Ecology, Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands
| | - Mónica Sánchez-Román
- Earth Sciences Department, Faculty of Science, Vrije Universiteit, Amsterdam, Netherlands
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25
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White RA, Soles SA, Brady AL, Southam G, Lim DS, Slater GF. Biosignatures Associated with Freshwater Microbialites. Life (Basel) 2020; 10:life10050066. [PMID: 32429118 PMCID: PMC7281397 DOI: 10.3390/life10050066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/11/2020] [Accepted: 05/11/2020] [Indexed: 12/18/2022] Open
Abstract
Freshwater microbialites (i.e., lithifying microbial mats) are quite rare in northern latitudes of the North American continent, with two lakes (Pavilion and Kelly Lakes) of southeastern BC containing a morphological variety of such structures. We investigated Kelly Lake microbialites using carbon isotope systematics, phospholipid fatty acids (PLFAs) and quantitative PCR to obtain biosignatures associated with microbial metabolism. δ13CDIC values (mean δ13CDIC −4.9 ± 1.1‰, n = 8) were not in isotopic equilibrium with the atmosphere; however, they do indicate 13C-depleted inorganic carbon into Kelly Lake. The values of carbonates on microbialite surfaces (δ13C) fell within the range predicted for equilibrium precipitation from ambient lake water δ13CDIC (−2.2 to −5.3‰). Deep microbialites (26 m) had an enriched δ13Ccarb value of −0.3 ± 0.5‰, which is a signature of photoautotrophy. The deeper microbialites (>20 m) had higher biomass estimates (via PLFAs), and a greater relative abundance of cyanobacteria (measured by 16S copies via qPCR). The majority of PLFAs constituted monounsaturated and saturated PLFAs, which is consistent with gram-negative bacteria, including cyanobacteria. The central PLFA δ13C values were highly depleted (−9.3 to −15.7‰) relative to δ13C values of bulk organic matter, suggesting a predominance of photoautotrophy. A heterotrophic signature was also detected via the depleted iso- and anteiso-15:0 lipids (−3.2 to −5.2‰). Based on our carbonate isotopic biosignatures, PLFA, and qPCR measurements, photoautotrophy is enriched in the microbialites of Kelly Lake. This photoautotrophy enrichment is consistent with the microbialites of neighboring Pavilion Lake. This indication of photoautotrophy within Kelly Lake at its deepest depths raises new insights into the limits of measurable carbonate isotopic biosignatures under light and nutrient limitations.
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Affiliation(s)
- Richard Allen White
- Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA;
- RAW Molecular Systems (RMS) LLC, Spokane, WA 99218, USA
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW 2052, Australia
| | - Sarah A. Soles
- School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (S.A.S.); (A.L.B.)
| | - Allyson L. Brady
- School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (S.A.S.); (A.L.B.)
| | - Gordon Southam
- School of Earth and Environmental Sciences, University of Queensland, QLD 4072, Australia;
| | | | - Greg F. Slater
- School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (S.A.S.); (A.L.B.)
- Correspondence: ; Tel.: +1-905-525-9140 (ext. 26388)
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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27
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Simões MF, Ottoni CA, Antunes A. Biogenic Metal Nanoparticles: A New Approach to Detect Life on Mars? Life (Basel) 2020; 10:E28. [PMID: 32245046 PMCID: PMC7151574 DOI: 10.3390/life10030028] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/13/2020] [Accepted: 03/19/2020] [Indexed: 01/02/2023] Open
Abstract
Metal nanoparticles (MNPs) have been extensively studied. They can be produced via different methods (physical, chemical, or biogenic), but biogenic synthesis has become more relevant, mainly for being referred by many as eco-friendly and more advantageous than others. Biogenic MNPs have been largely used in a wide variety of applications, from industry, to agriculture, to health sectors, among others. Even though they are increasingly researched and used, there is still space for exploring further applications and increasing their functionality and our understanding of their synthesis process. Here, we provide an overview of MNPs and biogenic MNPs, and we analyze the potential application of their formation process to astrobiology and the detection of life on Mars and other worlds. According to current knowledge, we suggest that they can be used as potential biosignatures in extra-terrestrial samples. We present the advantages and disadvantages of this approach, suggest further research, and propose its potential use for the search for life in future space exploration.
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Affiliation(s)
- Marta Filipa Simões
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau SAR, Hong Kong, China
| | | | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau SAR, Hong Kong, China
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28
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McLoughlin N, Grosch EG, Vullum PE, Guagliardo P, Saunders M, Wacey D. Critically testing olivine-hosted putative martian biosignatures in the Yamato 000593 meteorite-Geobiological implications. Geobiology 2019; 17:691-707. [PMID: 31478592 DOI: 10.1111/gbi.12361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 07/12/2019] [Accepted: 07/31/2019] [Indexed: 06/10/2023]
Abstract
On rocky planets such as Earth and Mars the serpentinization of olivine in ultramafic crust produces hydrogen that can act as a potential energy source for life. Direct evidence of fluid-rock interaction on Mars comes from iddingsite alteration veins found in martian meteorites. In the Yamato 000593 meteorite, putative biosignatures have been reported from altered olivines in the form of microtextures and associated organic material that have been compared to tubular bioalteration textures found in terrestrial sub-seafloor volcanic rocks. Here, we use a suite of correlative, high-sensitivity, in situ chemical, and morphological analyses to characterize and re-evaluate these microalteration textures in Yamato 000593, a clinopyroxenite from the shallow subsurface of Mars. We show that the altered olivine crystals have angular and micro-brecciated margins and are also highly strained due to impact-induced fracturing. The shape of the olivine microalteration textures is in no way comparable to microtunnels of inferred biological origin found in terrestrial volcanic glasses and dunites, and rather we argue that the Yamato 000593 microtextures are abiotic in origin. Vein filling iddingsite extends into the olivine microalteration textures and contains amorphous organic carbon occurring as bands and sub-spherical concentrations <300 nm across. We propose that a martian impact event produced the micro-brecciated olivine crystal margins that reacted with subsurface hydrothermal fluids to form iddingsite containing organic carbon derived from abiotic sources. These new data have implications for how we might seek potential biosignatures in ultramafic rocks and impact craters on both Mars and Earth.
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Affiliation(s)
| | - Eugene G Grosch
- Department of Geology, Rhodes University, Grahamstown, South Africa
| | - Per Erik Vullum
- SINTEF Materials and Chemistry, Trondheim, Norway
- Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Paul Guagliardo
- Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Perth, Western Australia, Australia
| | - Martin Saunders
- Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Perth, Western Australia, Australia
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - David Wacey
- Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Perth, Western Australia, Australia
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29
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Georgiou CD, McKay CP, Quinn RC, Kalaitzopoulou E, Papadea P, Skipitari M. The Oxygen Release Instrument: Space Mission Reactive Oxygen Species Measurements for Habitability Characterization, Biosignature Preservation Potential Assessment, and Evaluation of Human Health Hazards. Life (Basel) 2019; 9:E70. [PMID: 31461989 PMCID: PMC6789740 DOI: 10.3390/life9030070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/21/2019] [Accepted: 08/25/2019] [Indexed: 11/17/2022] Open
Abstract
We describe the design of an instrument, the OxR (for Oxygen Release), for the enzymatically specific and non-enzymatic detection and quantification of the reactive oxidant species (ROS), superoxide radicals (O2•-), and peroxides (O22-, e.g., H2O2) on the surface of Mars and Moon. The OxR instrument is designed to characterize planetary habitability, evaluate human health hazards, and identify sites with high biosignature preservation potential. The instrument can also be used for missions to the icy satellites of Saturn's Titan and Enceladus, and Jupiter's Europa. The principle of the OxR instrument is based on the conversion of (i) O2•- to O2 via its enzymatic dismutation (which also releases H2O2), and of (ii) H2O2 (free or released by the hydrolysis of peroxides and by the dismutation of O2•-) to O2 via enzymatic decomposition. At stages i and ii, released O2 is quantitatively detected by an O2 sensor and stoichiometrically converted to moles of O2•- and H2O2. A non-enzymatic alternative approach is also designed. These methods serve as the design basis for the construction of a new small-footprint instrument for specific oxidant detection. The minimum detection limit of the OxR instrument for O2•- and O22- in Mars, Lunar, and Titan regolith, and in Europa and Enceladus ice is projected to be 10 ppb. The methodology of the OxR instrument can be rapidly advanced to flight readiness by leveraging the Phoenix Wet Chemical Laboratory, or microfluidic sample processing technologies.
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Affiliation(s)
| | | | - Richard C Quinn
- SETI Institute, Carl Sagan Center, Mountain View, CA 94043, USA
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30
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Abstract
Transcriptomics studies the set of RNA transcripts produced by the genome using high-throughput sequencing and bioinformatics. This growing field has revolutionized our understanding of host-pathogen interactions, revealing new insights into the host response to influenza infection and vaccination. Studies using transcriptomics have identified a unique immunosignature for influenza discernable from other bacterial and viral pathogens, key transcriptional factors that discriminate early from late, mild versus severe, and symptomatic versus asymptomatic infection. Recent studies evaluating the host response to influenza vaccines have revealed key differences in live versus inactivated influenza vaccines, identified early transcriptional signatures that predict hemagglutinin antibody production following vaccination, increased our understanding of how adjuvants enhance the immune response to influenza vaccine antigens, and demonstrate biologic variability in the response to vaccination due to host factors. These studies demonstrate the potential for influenza transcriptomics to be applied to clinical care, understanding the mechanisms of infection, and informing vaccine development.
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Affiliation(s)
- Suchitra Rao
- Department of Pediatrics (Infectious Diseases, Hospital Medicine, Epidemiology), University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO, USA
| | - Debashis Ghosh
- Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, CO, USA
| | - Edwin J Asturias
- Department of Pediatrics (Pediatric Infectious Diseases), University of Colorado School of Medicine and Children's Hospital Colorado and Department of Epidemiology, Center for Global Health, Colorado School of Public Health, Aurora, CO, USA
| | - Adriana Weinberg
- Department of Medicine, Pathology and Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
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31
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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32
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Loiselle L, McCraig MA, Dyar MD, Léveillé R, Shieh SR, Southam G. A Spectral Comparison of Jarosites Using Techniques Relevant to the Robotic Exploration of Biosignatures on Mars. Life (Basel) 2018; 8:E61. [PMID: 30563260 PMCID: PMC6316503 DOI: 10.3390/life8040061] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/30/2018] [Accepted: 12/02/2018] [Indexed: 11/19/2022] Open
Abstract
The acidic sulfate-rich waters of the Meridiani Planum region were potentially a habitable environment for iron-oxidizing bacteria on ancient Mars. If life existed in this ancient martian environment, jarosite minerals precipitating in these waters may record evidence of this biological activity. Since the Meridiani jarosite is thermodynamically stable at the martian surface, any biosignatures preserved in the jarosites may be readily available for analysis in the current surface sediments during the ongoing robotic exploration of Mars. However, thermal decomposition experiments indicate that organic compound detection of sediments containing jarosite may be challenging when using pyrolysis experiments; the instrument commonly used to assess organic matter in martian samples. So, here, we assess if the biogenicity of the Meridiani-type jarosites can be determined using complimentary spectroscopic techniques also utilized during the robotic exploration of Mars, including the upcoming ExoMars2020 rover mission. An abiotic jarosite, synthesized following established protocols, and a biological jarosite counterpart, derived from a microbial enrichment culture of Rio Tinto river sediments, were used to compare four spectroscopy techniques employed in the robotic exploration of Mars (Raman spectroscopy, mid-infrared (IR) spectroscopy, visible near-infrared reflectance (VNIR) spectroscopy and Mössbauer spectroscopy) to determine if the complimentary information obtained using these instruments can help elucidate the biological influence of Meridiani-type jarosites. Raman spectral differences might be due to the presence of unreacted reagents in the synthetic spectra and not biological contributions. Reflectance (IR/VNIR) spectra might exhibit minor organic absorption contributions, but are observed in both sample spectra, and do not represent a biosignature. Mössbauer spectra show minor differences in fit parameters that are related to crystal morphology and are unrelated to the biological (i.e., organic) component of the system. Results of this study suggest that the identification of biosignatures in Meridiani-type jarosites using the in situ robotic exploration on Mars may be possible but will be challenging. Our work provides additional insight into extraterrestrial biosignature detection and data interpretation for Mars exploration and indicates that sample return missions are likely required to unequivocally resolve the possible biogenicity of the Meridiani sediments or other jarosite-containing sediments.
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Affiliation(s)
- Liane Loiselle
- Research School of Earth Sciences, The Australian National University, Acton, ACT 2601, Australia.
- Centre for Planetary Science and Exploration (CPSX), Department of Earth Sciences, Western University, London, ON N6A 5B7, Canada.
| | | | - M Darby Dyar
- Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075, USA.
| | - Richard Léveillé
- Department of Earth and Planetary Science, McGill University, Montreal, QC H3A 0E8, Canada.
| | - Sean R Shieh
- Centre for Planetary Science and Exploration (CPSX), Department of Earth Sciences, Western University, London, ON N6A 5B7, Canada.
| | - Gordon Southam
- School of Earth & Environmental Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
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Mora MF, Jones SM, Creamer J, Willis PA. Extraction of amino acids from aerogel for analysis by capillary electrophoresis. Implications for a mission concept to Enceladus' Plume. Electrophoresis 2017; 39:620-625. [PMID: 29136289 DOI: 10.1002/elps.201700323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/20/2017] [Accepted: 11/07/2017] [Indexed: 11/07/2022]
Abstract
Ocean worlds like Europa and Enceladus in the outer solar system are prime targets in the search for life beyond Earth. Enceladus is particularly interesting due to the presence of a water plume ejecting from the south polar region. The recent discovery of H2 in the plume, in addition to the presence of previously observed organic compounds, highlights the possibility of life in this moon. The plume provides materials from the underlying ocean that could be collected simply by flying through it. The presence of the plume means that material from the ocean is available for collection during a flyby, without the need for landing or complex sample handling operations such as scooping or drilling. An attractive approach to preserve the organics in particles collected during flyby encounters would be to utilize silica aerogel, the material used to collect particles at hypervelocity during the Stardust mission. Here we demonstrate amino acids can be extracted from aerogel simply by adding water. This simple liquid extraction method could be implemented during a mission prior to analysis with a liquid-based technique like capillary electrophoresis.
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Affiliation(s)
- Maria F Mora
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Steve M Jones
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Jessica Creamer
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Peter A Willis
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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34
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Foucher F, Hickman-Lewis K, Westall F, Brack A. A Statistical Approach to Illustrate the Challenge of Astrobiology for Public Outreach. Life (Basel) 2017; 7:life7040040. [PMID: 29072614 PMCID: PMC5745553 DOI: 10.3390/life7040040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 01/08/2023] Open
Abstract
In this study, we attempt to illustrate the competition that constitutes the main challenge of astrobiology, namely the competition between the probability of extraterrestrial life and its detectability. To illustrate this fact, we propose a simple statistical approach based on our knowledge of the Universe and the Milky Way, the Solar System, and the evolution of life on Earth permitting us to obtain the order of magnitude of the distance between Earth and bodies inhabited by more or less evolved past or present life forms, and the consequences of this probability for the detection of associated biosignatures. We thus show that the probability of the existence of evolved extraterrestrial forms of life increases with distance from the Earth while, at the same time, the number of detectable biosignatures decreases due to technical and physical limitations. This approach allows us to easily explain to the general public why it is very improbable to detect a signal of extraterrestrial intelligence while it is justified to launch space probes dedicated to the search for microbial life in the Solar System.
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Affiliation(s)
- Frédéric Foucher
- CNRS, Centre de Biophysique Moléculaire, UPR 4301, Rue Charles Sadron, CS80054, 45071 Orléans CEDEX, France.
| | - Keyron Hickman-Lewis
- CNRS, Centre de Biophysique Moléculaire, UPR 4301, Rue Charles Sadron, CS80054, 45071 Orléans CEDEX, France.
| | - Frances Westall
- CNRS, Centre de Biophysique Moléculaire, UPR 4301, Rue Charles Sadron, CS80054, 45071 Orléans CEDEX, France.
| | - André Brack
- CNRS, Centre de Biophysique Moléculaire, UPR 4301, Rue Charles Sadron, CS80054, 45071 Orléans CEDEX, France.
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35
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Kölbl D, Pignitter M, Somoza V, Schimak MP, Strbak O, Blazevic A, Milojevic T. Exploring Fingerprints of the Extreme Thermoacidophile Metallosphaera sedula Grown on Synthetic Martian Regolith Materials as the Sole Energy Sources. Front Microbiol 2017; 8:1918. [PMID: 29062303 PMCID: PMC5640722 DOI: 10.3389/fmicb.2017.01918] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/20/2017] [Indexed: 12/04/2022] Open
Abstract
The biology of metal transforming microorganisms is of a fundamental and applied importance for our understanding of past and present biogeochemical processes on Earth and in the Universe. The extreme thermoacidophile Metallosphaera sedula is a metal mobilizing archaeon, which thrives in hot acid environments (optimal growth at 74°C and pH 2.0) and utilizes energy from the oxidation of reduced metal inorganic sources. These characteristics of M. sedula make it an ideal organism to further our knowledge of the biogeochemical processes of possible life on extraterrestrial planetary bodies. Exploring the viability and metal extraction capacity of M. sedula living on and interacting with synthetic extraterrestrial minerals, we show that M. sedula utilizes metals trapped in the Martian regolith simulants (JSC Mars 1A; P-MRS; S-MRS; MRS07/52) as the sole energy sources. The obtained set of microbiological and mineralogical data suggests that M. sedula actively colonizes synthetic Martian regolith materials and releases free soluble metals. The surface of bioprocessed Martian regolith simulants is analyzed for specific mineralogical fingerprints left upon M. sedula growth. The obtained results provide insights of biomining of extraterrestrial material as well as of the detection of biosignatures implementing in life search missions.
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Affiliation(s)
- Denise Kölbl
- Extremophiles Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Marc Pignitter
- Department of Nutritional and Physiological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Veronika Somoza
- Department of Nutritional and Physiological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Mario P Schimak
- Department of Symbiosis, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Oliver Strbak
- Biomedical Center Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Amir Blazevic
- Extremophiles Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Tetyana Milojevic
- Extremophiles Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
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36
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O'Connor S, Edwards HGM, Ali EMA. The preservation of archaeological brain remains in a human skeleton. Philos Trans A Math Phys Eng Sci 2016; 374:rsta.2016.0208. [PMID: 27799437 DOI: 10.1098/rsta.2016.0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
The identification of biomass within the cranial cavity of a waterlogged human skeleton inside a fish-tailed wooden coffin from a nineteenth century burial has been confirmed as brain tissue. A comparison is made between the Raman spectra obtained in the current study with those from an Iron Age brain found in an isolated cranium dating from about 500 years BCE, the only other Raman spectroscopy study made of human brain recovered from waterlogged, archaeological excavations. The spectra give some surprisingly detailed information about the state of preservation of brain tissue in both burials, especially when it is realized that, unlike preserved bog bodies, no other soft tissue has survived. The biosignatures of proteinaceous brain material are well characterized. The presence of spectral signatures from extraneous cyanobacterial colonization in the depositional site of the Iron Age brain had been construed to be responsible in part for the unusual preservation of brain tissues in the waterlogged environment, but they were not detected in the current study of the nineteenth century brain. The challenges for Raman spectroscopic analysis of biomaterials under these conditions are reviewed in the light of the successful outcome of the experiments.This article is part of the themed issue 'Raman spectroscopy in art and archaeology'.
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Affiliation(s)
- Sonia O'Connor
- Department of Archaeological Sciences, School of Life Sciences, University of Bradford, Bradford BD7 1 DP, UK
| | - Howell G M Edwards
- Division of Chemical and Forensic Sciences, School of Life Sciences, University of Bradford, Bradford BD7 1 DP, UK
| | - Esam M A Ali
- Division of Chemical and Forensic Sciences, School of Life Sciences, University of Bradford, Bradford BD7 1 DP, UK
- Department of Forensic Medicine, University of Sohag, Sohag, Egypt
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37
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Leuchter AF, Hunter AM, Krantz DE, Cook IA. Rhythms and blues: modulation of oscillatory synchrony and the mechanism of action of antidepressant treatments. Ann N Y Acad Sci 2015; 1344:78-91. [PMID: 25809789 DOI: 10.1111/nyas.12742] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Treatments for major depressive disorder (MDD) act at different hierarchical levels of biological complexity, ranging from the individual synapse to the brain as a whole. Theories of antidepressant medication action traditionally have focused on the level of cell-to-cell interaction and synaptic neurotransmission. However, recent evidence suggests that modulation of synchronized electrical activity in neuronal networks is a common effect of antidepressant treatments, including not only medications, but also neuromodulatory treatments such as repetitive transcranial magnetic stimulation. Synchronization of oscillatory network activity in particular frequency bands has been proposed to underlie neurodevelopmental and learning processes, and also may be important in the mechanism of action of antidepressant treatments. Here, we review current research on the relationship between neuroplasticity and oscillatory synchrony, which suggests that oscillatory synchrony may help mediate neuroplastic changes related to neurodevelopment, learning, and memory, as well as medication and neuromodulatory treatment for MDD. We hypothesize that medication and neuromodulation treatments may have related effects on the rate and pattern of neuronal firing, and that these effects underlie antidepressant efficacy. Elucidating the mechanisms through which oscillatory synchrony may be related to neuroplasticity could lead to enhanced treatment strategies for MDD.
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Affiliation(s)
- Andrew F Leuchter
- Laboratory of Brain, Behavior, and Pharmacology, and the Depression Research and Clinic Program, Semel Institute for Neuroscience and Human Behavior at UCLA, Los Angeles, California; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California
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38
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Hegde S, Paulino-Lima IG, Kent R, Kaltenegger L, Rothschild L. Surface biosignatures of exo-earths: remote detection of extraterrestrial life. Proc Natl Acad Sci U S A 2015; 112:3886-91. [PMID: 25775594 DOI: 10.1073/pnas.1421237112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exoplanet discovery has made remarkable progress, with the first rocky planets having been detected in the central star's liquid water habitable zone. The remote sensing techniques used to characterize such planets for potential habitability and life rely solely on our understanding of life on Earth. The vegetation red edge from terrestrial land plants is often used as a direct signature of life, but it occupies only a small niche in the environmental parameter space that binds life on present-day Earth and has been widespread for only about 460 My. To more fully exploit the diversity of the one example of life known, we measured the spectral characteristics of 137 microorganisms containing a range of pigments, including ones isolated from Earth's most extreme environments. Our database covers the visible and near-infrared to the short-wavelength infrared (0.35-2.5 µm) portions of the electromagnetic spectrum and is made freely available from biosignatures.astro.cornell.edu. Our results show how the reflectance properties are dominated by the absorption of light by pigments in the visible portion and by strong absorptions by the cellular water of hydration in the infrared (up to 2.5 µm) portion of the spectrum. Our spectral library provides a broader and more realistic guide based on Earth life for the search for surface features of extraterrestrial life. The library, when used as inputs for modeling disk-integrated spectra of exoplanets, in preparation for the next generation of space- and ground-based instruments, will increase the chances of detecting life.
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39
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Marshall CP, Marshall AO. Raman spectroscopy as a screening tool for ancient life detection on Mars. Philos Trans A Math Phys Eng Sci 2014; 372:rsta.2014.0195. [PMID: 25368343 DOI: 10.1098/rsta.2014.0195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The search for sp(2)-bonded carbonaceous material is one of the major life detection strategies of the astrobiological exploration programmes of National Aeronautics and Space Administration and European Space Agency (ESA). The ESA ExoMars rover scheduled for launch in 2018 will include a Raman spectrometer with the goal of detecting sp(2)-bonded carbonaceous material as potential evidence of ancient life. However, sp(2)-bonded carbonaceous material will yield the same Raman spectra of well-developed G and D bands whether they are synthesized biologically or non-biologically. Therefore, the origin and source of sp(2)-bonded carbonaceous material cannot be elucidated by Raman spectroscopy alone. Here, we report the combined approach of Raman spectroscopy and gas chromatography-mass spectrometry biomarker analysis to Precambrian sedimentary rocks, which taken together, provides a promising new methodology for readily detecting and rapidly screening samples for immature organic material amenable to successful biomarker analysis.
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Affiliation(s)
- Craig P Marshall
- Department of Geology, The University of Kansas, Lawrence, KS 66045-7613, USA
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40
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Abstract
The goal of finding and characterizing nearby Earth-like planets is driving many NASA high-contrast flagship mission concepts, the latest of which is known as the Advanced Technology Large-Aperture Space Telescope (ATLAST). In this article, we calculate the optimal spectral resolution R = λ/δλ and minimum signal-to-noise ratio per spectral bin (SNR), two central design requirements for a high-contrast space mission, to detect signatures of water, oxygen, and chlorophyll on an Earth twin. We first develop a minimally parametric model and demonstrate its ability to fit synthetic and observed Earth spectra; this allows us to measure the statistical evidence for each component's presence. We find that water is the easiest to detect, requiring a resolution R ≳ 20, while the optimal resolution for oxygen is likely to be closer to R = 150, somewhat higher than the canonical value in the literature. At these resolutions, detecting oxygen will require approximately two times the SNR as water. Chlorophyll requires approximately six times the SNR as oxygen for an Earth twin, only falling to oxygen-like levels of detectability for a low cloud cover and/or a large vegetation covering fraction. This suggests designing a mission for sensitivity to oxygen and adopting a multitiered observing strategy, first targeting water, then oxygen on the more favorable planets, and finally chlorophyll on only the most promising worlds.
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Affiliation(s)
- Timothy D Brandt
- School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540
| | - David S Spiegel
- School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540
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Abstract
'Most habitable worlds in the cosmos will have no remotely detectable signs of life' is proposed as a biological hypothesis to be tested in the study of exoplanets. Habitable planets could be discovered elsewhere in the Universe, yet there are many hypothetical scenarios whereby the search for life on them could yield negative results. Scenarios for habitable worlds with no remotely detectable signatures of life include: planets that are habitable, but have no biosphere (Uninhabited Habitable Worlds); planets with life, but lacking any detectable surface signatures of that life (laboratory examples are provided); and planets with life, where the concentrations of atmospheric gases produced or removed by biota are impossible to disentangle from abiotic processes because of the lack of detailed knowledge of planetary conditions (the 'problem of exoplanet thermodynamic uncertainty'). A rejection of the hypothesis would require that the origin of life usually occurs on habitable planets, that spectrally detectable pigments and/or metabolisms that produce unequivocal biosignature gases (e.g. oxygenic photosynthesis) usually evolve and that the organisms that harbour them usually achieve a sufficient biomass to produce biosignatures detectable to alien astronomers.
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