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Erhart T, Nadegger C, Vergeiner S, Kreutz C, Müller T, Kräutler B. Novel Types of Phyllobilins in a Fern - Molecular Reporters of the Evolution of Chlorophyll Breakdown in the Paleozoic Era. Chemistry 2024; 30:e202401288. [PMID: 38634697 DOI: 10.1002/chem.202401288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Breakdown of chlorophyll (Chl), as studied in angiosperms, follows the pheophorbide a oxygenase/phyllobilin (PaO/PB) pathway, furnishing linear tetrapyrroles, named phyllobilins (PBs). In an investigation with fern leaves we have discovered iso-phyllobilanones (iPBs) with an intriguingly rearranged and oxidized carbon skeleton. We report here a key second group of iPBs from the fern and on their structure analysis. Previously, these additional Chl-catabolites escaped their characterization, since they exist in aqueous media as mixtures of equilibrating isomers. However, their chemical dehydration furnished stable iPB-derivatives that allowed the delineation of the enigmatic structures and chemistry of the original natural catabolites. The structures of all fern-iPBs reflect the early core steps of a PaO/PB-type pathway and the PB-to-iPB carbon skeleton rearrangement. A striking further degradative chemical ring-cleavage was observed, proposed to consume singlet molecular oxygen (1O2). Hence, Chl-catabolites may play a novel active role in detoxifying cellular 1O2. The critical deviations from the PaO/PB pathway, found in the fern, reflect evolutionary developments of Chl-breakdown in the green plants in the Paleozoic era.
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Affiliation(s)
- Theresia Erhart
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Christian Nadegger
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Stefan Vergeiner
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Thomas Müller
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Bernhard Kräutler
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
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2
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Gomes Gradíssimo D, Pereira Xavier L, Valadares Santos A. Cyanobacterial Polyhydroxyalkanoates: A Sustainable Alternative in Circular Economy. Molecules 2020; 25:E4331. [PMID: 32971731 PMCID: PMC7571216 DOI: 10.3390/molecules25184331] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/16/2020] [Accepted: 07/21/2020] [Indexed: 01/11/2023] Open
Abstract
Conventional petrochemical plastics have become a serious environmental problem. Its unbridled use, especially in non-durable goods, has generated an accumulation of waste that is difficult to measure, threatening aquatic and terrestrial ecosystems. The replacement of these plastics with cleaner alternatives, such as polyhydroxyalkanoates (PHA), can only be achieved by cost reductions in the production of microbial bioplastics, in order to compete with the very low costs of fossil fuel plastics. The biggest costs are carbon sources and nutrients, which can be appeased with the use of photosynthetic organisms, such as cyanobacteria, that have a minimum requirement for nutrients, and also using agro-industrial waste, such as the livestock industry, which in turn benefits from the by-products of PHA biotechnological production, for example pigments and nutrients. Circular economy can help solve the current problems in the search for a sustainable production of bioplastic: reducing production costs, reusing waste, mitigating CO2, promoting bioremediation and making better use of cyanobacteria metabolites in different industries.
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Affiliation(s)
- Diana Gomes Gradíssimo
- Post Graduation Program in Biotechnology, Institute of Biological Sciences, Universidade Federal do Pará, Augusto Corrêa Street, Guamá, Belém, PA 66075-110, Brazil
- Laboratory of Biotechnology of Enzymes and Biotransformations, Institute of Biological Sciences, Universidade Federal do Pará, Augusto Corrêa Street, Guamá, Belém, PA 66075-110, Brazil;
| | - Luciana Pereira Xavier
- Laboratory of Biotechnology of Enzymes and Biotransformations, Institute of Biological Sciences, Universidade Federal do Pará, Augusto Corrêa Street, Guamá, Belém, PA 66075-110, Brazil;
| | - Agenor Valadares Santos
- Post Graduation Program in Biotechnology, Institute of Biological Sciences, Universidade Federal do Pará, Augusto Corrêa Street, Guamá, Belém, PA 66075-110, Brazil
- Laboratory of Biotechnology of Enzymes and Biotransformations, Institute of Biological Sciences, Universidade Federal do Pará, Augusto Corrêa Street, Guamá, Belém, PA 66075-110, Brazil;
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Saona LA, Soria M, Villafañe PG, Lencina AI, Stepanenko T, Farías ME. Andean Microbial Ecosystems: Traces in Hypersaline Lakes About Life Origin. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/978-3-030-46087-7_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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4
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Nabhan S, Marin-Carbonne J, Mason PRD, Heubeck C. In situ S-isotope compositions of sulfate and sulfide from the 3.2 Ga Moodies Group, South Africa: A record of oxidative sulfur cycling. GEOBIOLOGY 2020; 18:426-444. [PMID: 32301171 DOI: 10.1111/gbi.12393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/12/2020] [Accepted: 02/27/2020] [Indexed: 06/11/2023]
Abstract
Sulfate minerals are rare in the Archean rock record and largely restricted to the occurrence of barite (BaSO4 ). The origin of this barite remains controversially debated. The mass-independent fractionation of sulfur isotopes in these and other Archean sedimentary rocks suggests that photolysis of volcanic aerosols in an oxygen-poor atmosphere played an important role in their formation. Here, we report on the multiple sulfur isotopic composition of sedimentary anhydrite in the ca. 3.22 Ga Moodies Group of the Barberton Greenstone Belt, southern Africa. Anhydrite occurs, together with barite and pyrite, in regionally traceable beds that formed in fluvial settings. Variable abundances of barite versus anhydrite reflect changes in sulfate enrichment by evaporitic concentration across orders of magnitude in an arid, nearshore terrestrial environment, periodically replenished by influxes of seawater. The multiple S-isotope compositions of anhydrite and pyrite are consistent with microbial sulfate reduction. S-isotope signatures in barite suggest an additional oxidative sulfate source probably derived from continental weathering of sulfide possibly enhanced by microbial sulfur oxidation. Although depositional environments of Moodies sulfate minerals differ strongly from marine barite deposits, their sulfur isotopic composition is similar and most likely reflects a primary isotopic signature. The data indicate that a constant input of small portions of oxidized sulfur from the continents into the ocean may have contributed to the observed long-term increase in Δ33 Ssulfate values through the Paleoarchean.
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Affiliation(s)
- Sami Nabhan
- Department for Geosciences, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Johanna Marin-Carbonne
- Laboratoire Magma et Volcans, Univ Lyon, UJM Saint Etienne, UBP, CNRS, IRD, St Etienne, France
- Institute of Earth Sciences, Universitè of Lausanne, Lausanne, Switzerland
| | - Paul R D Mason
- Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
| | - Christoph Heubeck
- Department for Geosciences, Friedrich-Schiller-Universität Jena, Jena, Germany
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5
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6
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Gayday I, Teplukhin A, Babikov D. Computational analysis of vibrational modes in tetra-sulfur using dimensionally reduced potential energy surface. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1574038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Igor Gayday
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
| | - Alexander Teplukhin
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
| | - Dmitri Babikov
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
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7
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Sarka K, Danielache SO, Kondorskiy A, Nanbu S. Theoretical study of electronic properties and isotope effects in the UV absorption spectrum of disulfur. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2018.08.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Schwieterman EW, Kiang NY, Parenteau MN, Harman CE, DasSarma S, Fisher TM, Arney GN, Hartnett HE, Reinhard CT, Olson SL, Meadows VS, Cockell CS, Walker SI, Grenfell JL, Hegde S, Rugheimer S, Hu R, Lyons TW. Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life. ASTROBIOLOGY 2018; 18:663-708. [PMID: 29727196 PMCID: PMC6016574 DOI: 10.1089/ast.2017.1729] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 12/10/2017] [Indexed: 05/04/2023]
Abstract
In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its fingerprint on the spectrum of our planet. Aided by the universality of the laws of physics and chemistry, we turn to Earth's biosphere, both in the present and through geologic time, for analog signatures that will aid in the search for life elsewhere. Considering the insights gained from modern and ancient Earth, and the broader array of hypothetical exoplanet possibilities, we have compiled a comprehensive overview of our current understanding of potential exoplanet biosignatures, including gaseous, surface, and temporal biosignatures. We additionally survey biogenic spectral features that are well known in the specialist literature but have not yet been robustly vetted in the context of exoplanet biosignatures. We briefly review advances in assessing biosignature plausibility, including novel methods for determining chemical disequilibrium from remotely obtainable data and assessment tools for determining the minimum biomass required to maintain short-lived biogenic gases as atmospheric signatures. We focus particularly on advances made since the seminal review by Des Marais et al. The purpose of this work is not to propose new biosignature strategies, a goal left to companion articles in this series, but to review the current literature, draw meaningful connections between seemingly disparate areas, and clear the way for a path forward. Key Words: Exoplanets-Biosignatures-Habitability markers-Photosynthesis-Planetary surfaces-Atmospheres-Spectroscopy-Cryptic biospheres-False positives. Astrobiology 18, 663-708.
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Affiliation(s)
- Edward W. Schwieterman
- Department of Earth Sciences, University of California, Riverside, California
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Blue Marble Space Institute of Science, Seattle, Washington
| | - Nancy Y. Kiang
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Goddard Institute for Space Studies, New York, New York
| | - Mary N. Parenteau
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Ames Research Center, Exobiology Branch, Mountain View, California
| | - Chester E. Harman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Goddard Institute for Space Studies, New York, New York
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland
- Institute of Marine and Environmental Technology, University System of Maryland, Baltimore, Maryland
| | - Theresa M. Fisher
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | - Giada N. Arney
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Hilairy E. Hartnett
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
| | - Christopher T. Reinhard
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Stephanie L. Olson
- Department of Earth Sciences, University of California, Riverside, California
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
| | - Victoria S. Meadows
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Astronomy Department, University of Washington, Seattle, Washington
| | - Charles S. Cockell
- University of Edinburgh School of Physics and Astronomy, Edinburgh, United Kingdom
- UK Centre for Astrobiology, Edinburgh, United Kingdom
| | - Sara I. Walker
- Blue Marble Space Institute of Science, Seattle, Washington
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona
- ASU-Santa Fe Institute Center for Biosocial Complex Systems, Arizona State University, Tempe, Arizona
| | - John Lee Grenfell
- Institut für Planetenforschung (PF), Deutsches Zentrum für Luft und Raumfahrt (DLR), Berlin, Germany
| | - Siddharth Hegde
- Carl Sagan Institute, Cornell University, Ithaca, New York
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York
| | - Sarah Rugheimer
- Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom
| | - Renyu Hu
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - Timothy W. Lyons
- Department of Earth Sciences, University of California, Riverside, California
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
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Meadows VS, Reinhard CT, Arney GN, Parenteau MN, Schwieterman EW, Domagal-Goldman SD, Lincowski AP, Stapelfeldt KR, Rauer H, DasSarma S, Hegde S, Narita N, Deitrick R, Lustig-Yaeger J, Lyons TW, Siegler N, Grenfell JL. Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment. ASTROBIOLOGY 2018; 18:630-662. [PMID: 29746149 PMCID: PMC6014580 DOI: 10.1089/ast.2017.1727] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/15/2017] [Indexed: 05/04/2023]
Abstract
We describe how environmental context can help determine whether oxygen (O2) detected in extrasolar planetary observations is more likely to have a biological source. Here we provide an in-depth, interdisciplinary example of O2 biosignature identification and observation, which serves as the prototype for the development of a general framework for biosignature assessment. Photosynthetically generated O2 is a potentially strong biosignature, and at high abundance, it was originally thought to be an unambiguous indicator for life. However, as a biosignature, O2 faces two major challenges: (1) it was only present at high abundance for a relatively short period of Earth's history and (2) we now know of several potential planetary mechanisms that can generate abundant O2 without life being present. Consequently, our ability to interpret both the presence and absence of O2 in an exoplanetary spectrum relies on understanding the environmental context. Here we examine the coevolution of life with the early Earth's environment to identify how the interplay of sources and sinks may have suppressed O2 release into the atmosphere for several billion years, producing a false negative for biologically generated O2. These studies suggest that planetary characteristics that may enhance false negatives should be considered when selecting targets for biosignature searches. We review the most recent knowledge of false positives for O2, planetary processes that may generate abundant atmospheric O2 without a biosphere. We provide examples of how future photometric, spectroscopic, and time-dependent observations of O2 and other aspects of the planetary environment can be used to rule out false positives and thereby increase our confidence that any observed O2 is indeed a biosignature. These insights will guide and inform the development of future exoplanet characterization missions. Key Words: Biosignatures-Oxygenic photosynthesis-Exoplanets-Planetary atmospheres. Astrobiology 18, 630-662.
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Affiliation(s)
- Victoria S. Meadows
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Christopher T. Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
| | - Giada N. Arney
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Mary N. Parenteau
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Ames Research Center, Exobiology Branch, Mountain View, California
| | - Edward W. Schwieterman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Department of Earth Sciences, University of California, Riverside, California
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- Blue Marble Space Institute of Science, Seattle, Washington
| | - Shawn D. Domagal-Goldman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Andrew P. Lincowski
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Karl R. Stapelfeldt
- NASA Exoplanet Exploration Program, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California
| | - Heike Rauer
- German Aerospace Center, Institute of Planetary Research, Extrasolar Planets and Atmospheres, Berlin, Germany
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland
- Institute of Marine and Environmental Technology, University System of Baltimore, Maryland
| | - Siddharth Hegde
- Carl Sagan Institute, Cornell University, Ithaca, New York
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York
| | - Norio Narita
- Department of Astronomy, The University of Tokyo, Tokyo, Japan
- Astrobiology Center, NINS, Tokyo, Japan
- National Astronomical Observatory of Japan, NINS, Tokyo, Japan
| | - Russell Deitrick
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Jacob Lustig-Yaeger
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Timothy W. Lyons
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Department of Earth Sciences, University of California, Riverside, California
| | - Nicholas Siegler
- NASA Exoplanet Exploration Program, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California
| | - J. Lee Grenfell
- German Aerospace Center, Institute of Planetary Research, Extrasolar Planets and Atmospheres, Berlin, Germany
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10
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Fakhraee M, Crowe SA, Katsev S. Sedimentary sulfur isotopes and Neoarchean ocean oxygenation. SCIENCE ADVANCES 2018; 4:e1701835. [PMID: 29376118 PMCID: PMC5783677 DOI: 10.1126/sciadv.1701835] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 12/19/2017] [Indexed: 05/22/2023]
Abstract
Abrupt disappearance of mass-independent fractionation of sulfur isotopes (MIF-S) from the geologic record and an apparent ingrowth in seawater sulfate around 2.45 billion years ago (Ga) signal the first large-scale oxygenation of the atmosphere [the Great Oxygenation Event (GOE)]. Pre-GOE O2 production is evident from multiple other terrestrial and marine proxies, but oceanic O2 concentrations remain poorly constrained. Furthermore, current interpretations of S isotope records do not explain a concurrent expansion in the range of both MIF-S-diagnostic for low atmospheric O2-and δ34S beginning at 2.7 Ga. To address these unknowns, we developed a reaction-transport model to analyze the preservation patterns of sulfur isotopes in Archean sedimentary pyrites, one of the most robust and widely distributed proxies for early Earth biogeochemistry. Our modeling, paradoxically, reveals that micromolar levels of O2 in seawater enhance the preservation of large MIF-S signals, whereas concomitant ingrowth of sulfate expands the ranges in pyrite δ34S. The 2.7- to 2.45-Ga expansion in both Δ33S and δ34S ranges thus argues for a widespread and protracted oxygenation of seawater, at least in shallow marine environments. At the micromolar levels predicted, the surface oceans would support a strong flux of O2 to the atmosphere, where O2 sinks balanced these fluxes until the GOE. This microoxic seawater would have provided habitat for early aerobic microorganisms and supported a diversity of new O2-driven biogeochemical cycles in the Neoarchean.
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Affiliation(s)
- Mojtaba Fakhraee
- Large Lakes Observatory, University of Minnesota Duluth, 2205 East 5th Street, Duluth, MN 55812, USA
| | - Sean A. Crowe
- Department of Microbiology and Immunology and Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Sergei Katsev
- Large Lakes Observatory, University of Minnesota Duluth, 2205 East 5th Street, Duluth, MN 55812, USA
- Department of Physics and Astronomy, University of Minnesota Duluth, Duluth, MN 55812, USA
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Abstract
Oxygenic photosynthesis is Earth's dominant metabolism, having evolved to harvest the largest expected energy source at the surface of most terrestrial habitable zone planets. Using CO2 and H2O-molecules that are expected to be abundant and widespread on habitable terrestrial planets-oxygenic photosynthesis is plausible as a significant planetary process with a global impact. Photosynthetic O2 has long been considered particularly robust as a sign of life on a habitable exoplanet, due to the lack of known "false positives"-geological or photochemical processes that could also produce large quantities of stable O2. O2 has other advantages as a biosignature, including its high abundance and uniform distribution throughout the atmospheric column and its distinct, strong absorption in the visible and near-infrared. However, recent modeling work has shown that false positives for abundant oxygen or ozone could be produced by abiotic mechanisms, including photochemistry and atmospheric escape. Environmental factors for abiotic O2 have been identified and will improve our ability to choose optimal targets and measurements to guard against false positives. Most of these false-positive mechanisms are dependent on properties of the host star and are often strongest for planets orbiting M dwarfs. In particular, selecting planets found within the conservative habitable zone and those orbiting host stars more massive than 0.4 M⊙ (M3V and earlier) may help avoid planets with abundant abiotic O2 generated by water loss. Searching for O4 or CO in the planetary spectrum, or the lack of H2O or CH4, could help discriminate between abiotic and biological sources of O2 or O3. In advance of the next generation of telescopes, thorough evaluation of potential biosignatures-including likely environmental context and factors that could produce false positives-ultimately works to increase our confidence in life detection. Key Words: Biosignatures-Exoplanets-Oxygen-Photosynthesis-Planetary spectra. Astrobiology 17, 1022-1052.
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Affiliation(s)
- Victoria S Meadows
- 1 Department of Astronomy and Astrobiology Program, University of Washington , Seattle, Washington
- 2 NASA Astrobiology Institute-Virtual Planetary Laboratory , USA
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12
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Sarka K, Danielache SO, Kondorskiy A, Nanbu S. RETRACTED: Theoretical study of electronic properties and isotope effects in the UV absorption spectrum of disulfur. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Ishida T, Nanbu S, Nakamura H. Clarification of nonadiabatic chemical dynamics by the Zhu-Nakamura theory of nonadiabatic transition: from tri-atomic systems to reactions in solutions. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1293399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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Recombination reactions as a possible mechanism of mass-independent fractionation of sulfur isotopes in the Archean atmosphere of Earth. Proc Natl Acad Sci U S A 2017; 114:3062-3067. [PMID: 28258172 DOI: 10.1073/pnas.1620977114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A hierarchy of isotopically substituted recombination reactions is formulated for production of sulfur allotropes in the anoxic atmosphere of Archean Earth. The corresponding system of kinetics equations is solved analytically to obtain concise expressions for isotopic enrichments, with focus on mass-independent isotope effects due to symmetry, ignoring smaller mass-dependent effects. Proper inclusion of atom-exchange processes is shown to be important. This model predicts significant and equal depletions driven by reaction stoichiometry for all rare isotopes: 33S, 34S, and 36S. Interestingly, the ratio of capital [Formula: see text] values obtained within this model for 33S and 36S is -1.16, very close to the mass-independent fractionation line of the Archean rock record. This model may finally offer a mechanistic explanation for the striking mass-independent fractionation of sulfur isotopes that took place in the Archean atmosphere of Earth.
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Terrett R, Frankcombe T, Pace R, Stranger R. Effect of concomitant oxidation and deprotonation of hydrated Mn centres in rationalising the FTIR difference silence of D1-Asp170 in Photosystem II. J Inorg Biochem 2015; 155:101-4. [PMID: 26684583 DOI: 10.1016/j.jinorgbio.2015.11.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/29/2015] [Accepted: 11/24/2015] [Indexed: 11/28/2022]
Abstract
The observation of negligible FTIR differences in carboxylate vibrational modes for the D1-Asp170 residue of Photosystem II (PSII) on successive one-electron oxidations of the Mn4CaO5 oxygen-evolving complex (OEC) is counterintuitive in light of the apparent ligation of D1-Asp170 to an oxidisable Mn ion in the X-ray crystallographic structures of PSII. Here, we show computational support for the hypothesis that suppression of the FTIR difference spectrum in the 1100cm(-1) to 1700cm(-1) region of D1-Asp170 occurs by concomitant Mn oxidation and deprotonation of water ligands bound to the ligated metal centre. Density functional theory calculations on the model species [Mn(II)Ca(COOH)(OH)2(H2O)2](+) over two successive oxidations of the Mn ion are performed, where those oxidations are accompanied by deprotonation of water and μ-hydroxo ligands coordinated to the Mn ion. In contrast, dramatically increased FTIR difference activity is observed where these oxidations are unaccompanied by proton loss.
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Affiliation(s)
- Richard Terrett
- Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia
| | - Terry Frankcombe
- Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia; School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2610, Australia
| | - Ron Pace
- Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia
| | - Robert Stranger
- Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia.
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17
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Yang H, Liao L, Bo T, Zhao L, Sun X, Lu X, Norling B, Huang F. Slr0151 in Synechocystis sp. PCC 6803 is required for efficient repair of photosystem II under high-light condition. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:1136-50. [PMID: 25146729 DOI: 10.1111/jipb.12275] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 08/18/2014] [Indexed: 05/06/2023]
Abstract
Cyanobacteria are ancient photosynthetic prokaryotes that have adapted successfully to adverse environments including high-light irradiation. Although it is known that the repair of photodamaged photosystem II (PSII) in the organisms is a highly regulated process, our knowledge of the molecular components that regulate each step of the process is limited. We have previously identified a hypothetical protein Slr0151 in the membrane fractions of cyanobacterium Synechocystis sp. PCC 6803. Here, we report that Slr0151 is involved in PSII repair of the organism. We generated a mutant strain (Δslr0151) lacking the protein Slr0151 and analyzed its characteristics under normal and high-light conditions. Targeted deletion of slr0151 resulted in decreased PSII activity in Synechocystis. Moreover, the mutant exhibited increased photoinhibition due to impairment of PSII repair under high-light condition. Further analysis using in vivo radioactive labeling and 2-D blue native/sodium dodecylsulfate polyacrylamide gel electrophoresis indicated that the PSII repair cycle was hindered at the levels of D1 synthesis and disassembly and/or assembly of PSII in the mutant. Protein interaction assays demonstrated that Slr0151 interacts with D1 and CP43 proteins. Taken together, these results indicate that Slr0151 plays an important role in regulating PSII repair in the organism under high-light stress condition.
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Affiliation(s)
- Haomeng Yang
- Key Laboratory of Photobiology, Institute of Botany, the Chinese Academy of Sciences, Beijing, 100093, China
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Gaudana SB, Krishnakumar S, Alagesan S, Digmurti MG, Viswanathan GA, Chetty M, Wangikar PP. Rhythmic and sustained oscillations in metabolism and gene expression of Cyanothece sp. ATCC 51142 under constant light. Front Microbiol 2013; 4:374. [PMID: 24367360 PMCID: PMC3854555 DOI: 10.3389/fmicb.2013.00374] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/21/2013] [Indexed: 11/13/2022] Open
Abstract
Cyanobacteria, a group of photosynthetic prokaryotes, oscillate between day and night time metabolisms with concomitant oscillations in gene expression in response to light/dark cycles (LD). The oscillations in gene expression have been shown to sustain in constant light (LL) with a free running period of 24 h in a model cyanobacterium Synechococcus elongatus PCC 7942. However, equivalent oscillations in metabolism are not reported under LL in this non-nitrogen fixing cyanobacterium. Here we focus on Cyanothece sp. ATCC 51142, a unicellular, nitrogen-fixing cyanobacterium known to temporally separate the processes of oxygenic photosynthesis and oxygen-sensitive nitrogen fixation. In a recent report, metabolism of Cyanothece 51142 has been shown to oscillate between photosynthetic and respiratory phases under LL with free running periods that are temperature dependent but significantly shorter than the circadian period. Further, the oscillations shift to circadian pattern at moderate cell densities that are concomitant with slower growth rates. Here we take this understanding forward and demonstrate that the ultradian rhythm under LL sustains at much higher cell densities when grown under turbulent regimes that simulate flashing light effect. Our results suggest that the ultradian rhythm in metabolism may be needed to support higher carbon and nitrogen requirements of rapidly growing cells under LL. With a comprehensive Real time PCR based gene expression analysis we account for key regulatory interactions and demonstrate the interplay between clock genes and the genes of key metabolic pathways. Further, we observe that several genes that peak at dusk in Synechococcus peak at dawn in Cyanothece and vice versa. The circadian rhythm of this organism appears to be more robust with peaking of genes in anticipation of the ensuing photosynthetic and respiratory metabolic phases.
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Affiliation(s)
- Sandeep B Gaudana
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
| | - S Krishnakumar
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
| | - Swathi Alagesan
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
| | - Madhuri G Digmurti
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
| | - Ganesh A Viswanathan
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
| | - Madhu Chetty
- Gippsland School of Information Technology, Monash University VIC, Australia
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, India
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Sherman LA, Wangikar PP, Swarup R, Kasture S. Highlights from the Indo-US workshop "Cyanobacteria: molecular networks to biofuels" held at Lonavala, India during December 16-20, 2012. PHOTOSYNTHESIS RESEARCH 2013; 118:1-8. [PMID: 24142037 DOI: 10.1007/s11120-013-9933-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An Indo-US workshop on "Cyanobacteria: molecular networks to biofuels" was held December 16-20, 2012 at Lagoona Resort, Lonavala, India. The workshop was jointly organized by two of the authors, PPW, a chemical engineer and LAS, a biologist, thereby ensuring a broad and cross-disciplinary participation. The main objective of the workshop was to bring researchers from academia and industry of the two countries together with common interests in cyanobacteria or microalgae and derived biofuels. An exchange of ideas resulted from a series of oral and poster presentations and, importantly, through one-on-one discussions during tea breaks and meals. Another key objective was to introduce young researchers of India to the exciting field of cyanobacterial physiology, modeling, and biofuels. PhD students and early stage researchers were especially encouraged to participate and about half of the 75 participants belonged to this category. The rest were comprised of senior researchers, including 13-15 invited speakers from each country. Overall, twenty-four institutes from 12 states of India were represented. The deliberations, which are being compiled in the present special issue, revolved mainly around molecular aspects of cyanobacterial biofuels including metabolic engineering, networks, genetic regulation, circadian rhythms, and stress responses. Representatives of some key funding agencies and industry provided a perspective and opportunities in the field and for bilateral collaboration. This article summarizes deliberations that took place at the meeting and provides a bird's eye view of the ongoing research in the field in the two countries.
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Affiliation(s)
- Louis A Sherman
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, 915 W. State St, West Lafayette, IN, 47907, USA,
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Bonilla-Rosso G, Peimbert M, Alcaraz LD, Hernández I, Eguiarte LE, Olmedo-Alvarez G, Souza V. Comparative metagenomics of two microbial mats at Cuatro Ciénegas Basin II: community structure and composition in oligotrophic environments. ASTROBIOLOGY 2012; 12:659-73. [PMID: 22920516 PMCID: PMC3426889 DOI: 10.1089/ast.2011.0724] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Microbial mats are self-sustained, functionally complex ecosystems that make good models for the understanding of past and present microbial ecosystems as well as putative extraterrestrial ecosystems. Ecological theory suggests that the composition of these communities might be affected by nutrient availability and disturbance frequency. We characterized two microbial mats from two contrasting environments in the oligotrophic Cuatro Ciénegas Basin: a permanent green pool and a red desiccation pond. We analyzed their taxonomic structure and composition by means of 16S rRNA clone libraries and metagenomics and inferred their metabolic role by the analysis of functional traits in the most abundant organisms. Both mats showed a high diversity with metabolically diverse members and strongly differed in structure and composition. The green mat had a higher species richness and evenness than the red mat, which was dominated by a lineage of Pseudomonas. Autotrophs were abundant in the green mat, and heterotrophs were abundant in the red mat. When comparing with other mats and stromatolites, we found that taxonomic composition was not shared at species level but at order level, which suggests environmental filtering for phylogenetically conserved functional traits with random selection of particular organisms. The highest diversity and composition similarity was observed among systems from stable environments, which suggests that disturbance regimes might affect diversity more strongly than nutrient availability, since oligotrophy does not appear to prevent the establishment of complex and diverse microbial mat communities. These results are discussed in light of the search for extraterrestrial life.
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Affiliation(s)
- Germán Bonilla-Rosso
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, México D.F., México
| | - Mariana Peimbert
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana, Cuajimalpa, Álvaro Obregón, México D.F., México
| | - Luis David Alcaraz
- Departamento de Genómica y Salud, Centro Superior de Investigación en Salud Pública, Valencia, España
| | - Ismael Hernández
- Departamento de Ingeniería Genética, Cinvestav, Campus Guanajuato, Irapuato, México
| | - Luis E. Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, México D.F., México
| | | | - Valeria Souza
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, México D.F., México
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Buchko GW, Robinson H. Crystal structure of cce_0566 from Cyanothece 51142, a protein associated with nitrogen fixation in the DUF269 family. FEBS Lett 2012; 586:350-5. [PMID: 22289180 PMCID: PMC3641832 DOI: 10.1016/j.febslet.2012.01.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 01/16/2012] [Accepted: 01/16/2012] [Indexed: 11/24/2022]
Abstract
The crystal structure for cce_0566 (171 aa, 19.4 kDa), a DUF269 annotated protein from the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142, was determined to 1.60Å resolution. Cce_0566 is a homodimer with each molecule composed of eight α-helices folded on one side of a three strand anti-parallel β-sheet. Hydrophobic interactions between the side chains of largely conserved residues on the surface of each β-sheet hold the dimer together. The fold observed for cce_0566 may be unique to proteins in the DUF269 family, hence, the protein may also have a function unique to nitrogen fixation. A solvent accessible cleft containing conserved charged residues near the dimer interface could represent the active site or ligand-binding surface for the protein's biological function.
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Affiliation(s)
- Garry W Buchko
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
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Bandyopadhyay A, Elvitigala T, Welsh E, Stöckel J, Liberton M, Min H, Sherman LA, Pakrasi HB. Novel metabolic attributes of the genus cyanothece, comprising a group of unicellular nitrogen-fixing Cyanothece. mBio 2011; 2:e00214-11. [PMID: 21972240 PMCID: PMC3187577 DOI: 10.1128/mbio.00214-11] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 09/12/2011] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The genus Cyanothece comprises unicellular cyanobacteria that are morphologically diverse and ecologically versatile. Studies over the last decade have established members of this genus to be important components of the marine ecosystem, contributing significantly to the nitrogen and carbon cycle. System-level studies of Cyanothece sp. ATCC 51142, a prototypic member of this group, revealed many interesting metabolic attributes. To identify the metabolic traits that define this class of cyanobacteria, five additional Cyanothece strains were sequenced to completion. The presence of a large, contiguous nitrogenase gene cluster and the ability to carry out aerobic nitrogen fixation distinguish Cyanothece as a genus of unicellular, aerobic nitrogen-fixing cyanobacteria. Cyanothece cells can create an anoxic intracellular environment at night, allowing oxygen-sensitive processes to take place in these oxygenic organisms. Large carbohydrate reserves accumulate in the cells during the day, ensuring sufficient energy for the processes that require the anoxic phase of the cells. Our study indicates that this genus maintains a plastic genome, incorporating new metabolic capabilities while simultaneously retaining archaic metabolic traits, a unique combination which provides the flexibility to adapt to various ecological and environmental conditions. Rearrangement of the nitrogenase cluster in Cyanothece sp. strain 7425 and the concomitant loss of its aerobic nitrogen-fixing ability suggest that a similar mechanism might have been at play in cyanobacterial strains that eventually lost their nitrogen-fixing ability. IMPORTANCE The unicellular cyanobacterial genus Cyanothece has significant roles in the nitrogen cycle in aquatic and terrestrial environments. Cyanothece sp. ATCC 51142 was extensively studied over the last decade and has emerged as an important model photosynthetic microbe for bioenergy production. To expand our understanding of the distinctive metabolic capabilities of this cyanobacterial group, we analyzed the genome sequences of five additional Cyanothece strains from different geographical habitats, exhibiting diverse morphological and physiological attributes. These strains exhibit high rates of N(2) fixation and H(2) production under aerobic conditions. They can generate copious amounts of carbohydrates that are stored in large starch-like granules and facilitate energy-intensive processes during the dark, anoxic phase of the cells. The genomes of some Cyanothece strains are quite unique in that there are linear elements in addition to a large circular chromosome. Our study provides novel insights into the metabolism of this class of unicellular nitrogen-fixing cyanobacteria.
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Affiliation(s)
| | | | - Eric Welsh
- Biomedical Informatics Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA; and
| | - Jana Stöckel
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Michelle Liberton
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Hongtao Min
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Louis A. Sherman
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
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Microbial Diversity in Modern Stromatolites. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2011. [DOI: 10.1007/978-94-007-0397-1_17] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Farquhar J, Zerkle AL, Bekker A. Geological constraints on the origin of oxygenic photosynthesis. PHOTOSYNTHESIS RESEARCH 2011; 107:11-36. [PMID: 20882345 DOI: 10.1007/s11120-010-9594-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 08/18/2010] [Indexed: 05/29/2023]
Abstract
This article examines the geological evidence for the rise of atmospheric oxygen and the origin of oxygenic photosynthesis. The evidence for the rise of atmospheric oxygen places a minimum time constraint before which oxygenic photosynthesis must have developed, and was subsequently established as the primary control on the atmospheric oxygen level. The geological evidence places the global rise of atmospheric oxygen, termed the Great Oxidation Event (GOE), between ~2.45 and ~2.32 Ga, and it is captured within the Duitschland Formation, which shows a transition from mass-independent to mass-dependent sulfur isotope fractionation. The rise of atmospheric oxygen during this interval is closely associated with a number of environmental changes, such as glaciations and intense continental weathering, and led to dramatic changes in the oxidation state of the ocean and the seawater inventory of transition elements. There are other features of the geologic record predating the GOE by as much as 200-300 million years, perhaps extending as far back as the Mesoarchean-Neoarchean boundary at 2.8 Ga, that suggest the presence of low level, transient or local, oxygenation. If verified, these features would not only imply an earlier origin for oxygenic photosynthesis, but also require a mechanism to decouple oxygen production from oxidation of Earth's surface environments. Most hypotheses for the GOE suggest that oxygen production by oxygenic photosynthesis is a precondition for the rise of oxygen, but that a synchronous change in atmospheric oxygen level is not required by the onset of this oxygen source. The potential lag-time in the response of Earth surface environments is related to the way that oxygen sinks, such as reduced Fe and sulfur compounds, respond to oxygen production. Changes in oxygen level imply an imbalance in the sources and sinks for oxygen. Changes in the cycling of oxygen have occurred at various times before and after the GOE, and do not appear to require corresponding changes in the intensity of oxygenic photosynthesis. The available geological constraints for these changes do not, however, disallow a direct role for this metabolism. The geological evidence for early oxygen and hypotheses for the controls on oxygen level are the basis for the interpretation of photosynthetic oxygen production as examined in this review.
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Affiliation(s)
- James Farquhar
- Department of Geology and ESSIC, University of Maryland, College Park, MD 20742, USA.
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DeWitt HL, Hasenkopf CA, Trainer MG, Farmer DK, Jimenez JL, McKay CP, Toon OB, Tolbert MA. The formation of sulfate and elemental sulfur aerosols under varying laboratory conditions: implications for early earth. ASTROBIOLOGY 2010; 10:773-781. [PMID: 21087157 DOI: 10.1089/ast.2009.9455] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The presence of sulfur mass-independent fractionation (S-MIF) in sediments more than 2.45 × 10(9) years old is thought to be evidence for an early anoxic atmosphere. Photolysis of sulfur dioxide (SO(2)) by UV light with λ < 220 nm has been shown in models and some initial laboratory studies to create a S-MIF; however, sulfur must leave the atmosphere in at least two chemically different forms to preserve any S-MIF signature. Two commonly cited examples of chemically different sulfur species that could have exited the atmosphere are elemental sulfur (S(8)) and sulfuric acid (H(2)SO(4)) aerosols. Here, we use real-time aerosol mass spectrometry to directly detect the sulfur-containing aerosols formed when SO(2) either photolyzes at wavelengths from 115 to 400 nm, to simulate the UV solar spectrum, or interacts with high-energy electrons, to simulate lightning. We found that sulfur-containing aerosols form under all laboratory conditions. Further, the addition of a reducing gas, in our experiments hydrogen (H(2)) or methane (CH(4)), increased the formation of S(8). With UV photolysis, formation of S(8) aerosols is highly dependent on the initial SO(2) pressure; and S(8) is only formed at a 2% SO(2) mixing ratio and greater in the absence of a reductant, and at a 0.2% SO(2) mixing ratio and greater in the presence of 1000 ppmv CH(4). We also found that organosulfur compounds are formed from the photolysis of CH(4) and moderate amounts of SO(2). The implications for sulfur aerosols on early Earth are discussed. Key Words: S-MIF-Archean atmosphere-Early Earth-Sulfur aerosols.
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Affiliation(s)
- H Langley DeWitt
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
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Wegener KM, Singh AK, Jacobs JM, Elvitigala T, Welsh EA, Keren N, Gritsenko MA, Ghosh BK, Camp DG, Smith RD, Pakrasi HB. Global proteomics reveal an atypical strategy for carbon/nitrogen assimilation by a cyanobacterium under diverse environmental perturbations. Mol Cell Proteomics 2010; 9:2678-89. [PMID: 20858728 DOI: 10.1074/mcp.m110.000109] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to accommodate periodic changes in environmental conditions. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses. Toward this goal, we have performed a large-scale proteomic analysis of the widely studied model cyanobacterium Synechocystis sp. PCC 6803 under 33 different environmental conditions. The resulting high-quality dataset consists of 22,318 unique peptides corresponding to 1955 proteins, a coverage of 53% of the predicted proteome. Quantitative determination of protein abundances has led to the identification of 1198 differentially regulated proteins. Notably, our analysis revealed that a common stress response under various environmental perturbations, irrespective of amplitude and duration, is the activation of atypical pathways for the acquisition of carbon and nitrogen from urea and arginine. In particular, arginine is catabolized via putrescine to produce succinate and glutamate, sources of carbon and nitrogen, respectively. This study provides the most comprehensive functional and quantitative analysis of the Synechocystis proteome to date, and shows that a significant stress response of cyanobacteria involves an uncommon mode of acquisition of carbon and nitrogen.
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Singh AK, Elvitigala T, Cameron JC, Ghosh BK, Bhattacharyya-Pakrasi M, Pakrasi HB. Integrative analysis of large scale expression profiles reveals core transcriptional response and coordination between multiple cellular processes in a cyanobacterium. BMC SYSTEMS BIOLOGY 2010; 4:105. [PMID: 20678200 PMCID: PMC2924297 DOI: 10.1186/1752-0509-4-105] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Accepted: 08/02/2010] [Indexed: 12/30/2022]
Abstract
BACKGROUND Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis. They play significant roles in global biogeochemical cycles and carbon sequestration, and have recently been recognized as potential vehicles for production of renewable biofuels. Synechocystis sp. PCC 6803 has been extensively used as a model organism for cyanobacterial studies. DNA microarray studies in Synechocystis have shown varying degrees of transcriptome reprogramming under altered environmental conditions. However, it is not clear from published work how transcriptome reprogramming affects pre-existing networks of fine-tuned cellular processes. RESULTS We have integrated 163 transcriptome data sets generated in response to numerous environmental and genetic perturbations in Synechocystis. Our analyses show that a large number of genes, defined as the core transcriptional response (CTR), are commonly regulated under most perturbations. The CTR contains nearly 12% of Synechocystis genes found on its chromosome. The majority of genes in the CTR are involved in photosynthesis, translation, energy metabolism and stress protection. Our results indicate that a large number of differentially regulated genes identified in most reported studies in Synechocystis under different perturbations are associated with the general stress response. We also find that a majority of genes in the CTR are coregulated with 25 regulatory genes. Some of these regulatory genes have been implicated in cellular responses to oxidative stress, suggesting that reactive oxygen species are involved in the regulation of the CTR. A Bayesian network, based on the regulation of various KEGG pathways determined from the expression patterns of their associated genes, has revealed new insights into the coordination between different cellular processes. CONCLUSION We provide here the first integrative analysis of transcriptome data sets generated in a cyanobacterium. This compilation of data sets is a valuable resource to researchers for all cyanobacterial gene expression related queries. Importantly, our analysis provides a global description of transcriptional reprogramming under different perturbations and a basic framework to understand the strategies of cellular adaptations in Synechocystis.
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Affiliation(s)
- Abhay K Singh
- Department of Biology, Washington University, St Louis, MO 63130, USA
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McGuinness ET. Some Molecular Moments of the Hadean and Archaean Aeons: A Retrospective Overview from the Interfacing Years of the Second to Third Millennia. Chem Rev 2010; 110:5191-215. [DOI: 10.1021/cr050061l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Eugene T. McGuinness
- Department of Chemistry & Biochemistry, Seton Hall University, South Orange, New Jersey 07079-2690
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Past, Present, and Future: Microbial Mats as Models for Astrobiological Research. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2010. [DOI: 10.1007/978-90-481-3799-2_29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Grant DJ, Dixon DA, Francisco JS, Feller D, Peterson KA. Heats of Formation of the H1,2OmSn (m, n = 0−3) Molecules from Electronic Structure Calculations. J Phys Chem A 2009; 113:11343-53. [DOI: 10.1021/jp905847e] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Joseph S. Francisco
- Department of Chemistry, H. C. Brown Laboratory, Purdue University, West Lafayette, Indiana 47907-1393
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Srinivasan N, Golbeck JH. Protein–cofactor interactions in bioenergetic complexes: The role of the A1A and A1B phylloquinones in Photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1057-88. [DOI: 10.1016/j.bbabio.2009.04.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 04/14/2009] [Accepted: 04/22/2009] [Indexed: 10/20/2022]
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Jagannathan B, Golbeck JH. Understanding of the binding interface between PsaC and the PsaA/PsaB heterodimer in photosystem I. Biochemistry 2009; 48:5405-16. [PMID: 19432395 DOI: 10.1021/bi900243f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The PsaC subunit of Photosystem I (PS I) is tightly bound to the PsaA/PsaB heterodimer via an extensive network of ionic and hydrogen bonds. To improve our understanding of the design of the PsaC-PsaA/PsaB binding interface, variants of PsaC were generated, each lacking a key binding contact with the PsaA/PsaB heterodimer. The characteristics of the reconstituted, variant PS I complexes were monitored by time-resolved optical spectroscopy, low-temperature EPR spectroscopy, and electron transfer throughput measurements. In the absence of the ionic bond forming contacts R52(C) or R65(C), a markedly slower charge recombination occurs between P(700)(+) and [F(A)/F(B)](-). The addition of PsaD leads to the restoration of native recombination kinetics in a fraction of the PS I complexes reconstituted with R52A(C), but not with R65A(C). Contrary to expectation, the absence of Y80(C), which forms two symmetry-breaking H-bonds with PsaB, does not significantly affect the binding of PsaC as judged by the rate of charge recombination between P(700)(+) and [F(A)/F(B)](-). However, the removal of the entire C-terminus results in a dramatic decrease in the rate of charge recombination. Low-temperature EPR spectra of the variant PS I complexes indicate that the magnetic environments of F(A) and F(B) are altered when compared to that of native PS I. The slowing of the rate of charge recombination in the variant PS I complexes could be due to an increase in the distance between F(X) and F(A)/F(B) as the result of non-native binding or to an altered reduction potential of the iron-sulfur clusters, which would result in a different rate of thermalization up the electron acceptor chain. The most significant finding is that the variant PS I complexes support lower rates of light-induced flavodoxin reduction and that the rates deteriorate rapidly on exposure to dioxygen due to the degradation of F(A) and F(B). We suggest that the extensive set of ionic bonds and H-bonds between PsaC and the PsaA/PsaB heterodimer has evolved to ensure an exceedingly tight binding interface, thereby rendering the [4Fe-4S] clusters in PsaC inaccessible to dioxygen at the onset of oxygenic photosynthesis.
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Affiliation(s)
- Bharat Jagannathan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University,University Park, Pennsylvania 16802, USA
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Simons MJP. The evolution of the cyanobacterial posttranslational clock from a primitive "phoscillator". J Biol Rhythms 2009; 24:175-82. [PMID: 19465694 DOI: 10.1177/0748730409333953] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cyanobacteria were among the 1st organisms to evolve on earth. The molecular circadian clock proteins of cyanobacteria and their phylogenetics have recently been elucidated. This allows for a conjecture on the evolution of 1 of the 1st circadian clocks. A scenario has now been created by combining known in vitro and in vivo properties of the 3 clock proteins of cyanobacteria (KaiA, KaiB, and KaiC). This scenario describes the evolution of the cyanobacterial clock in gradual steps: evolving from a masking mechanism, toward an hourglass, into a clock.
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Affiliation(s)
- Mirre J P Simons
- Department of Chronobiology, University of Groningen, Haren, The Netherlands.
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On the free energy that drove primordial anabolism. Int J Mol Sci 2009; 10:1853-1871. [PMID: 19468343 PMCID: PMC2680651 DOI: 10.3390/ijms10041853] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 04/16/2009] [Accepted: 04/20/2009] [Indexed: 12/25/2022] Open
Abstract
A key problem in understanding the origin of life is to explain the mechanism(s) that led to the spontaneous assembly of molecular building blocks that ultimately resulted in the appearance of macromolecular structures as they are known in modern biochemistry today. An indispensable thermodynamic prerequisite for such a primordial anabolism is the mechanistic coupling to processes that supplied the free energy required. Here I review different sources of free energy and discuss the potential of each form having been involved in the very first anabolic reactions that were fundamental to increase molecular complexity and thus were essential for life.
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Watanabe Y, Farquhar J, Ohmoto H. Anomalous Fractionations of Sulfur Isotopes During Thermochemical Sulfate Reduction. Science 2009; 324:370-3. [DOI: 10.1126/science.1169289] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Buchko GW, Robinson H, Addlagatta A. Structural characterization of the protein cce_0567 from Cyanothece 51142, a metalloprotein associated with nitrogen fixation in the DUF683 family. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1794:627-33. [PMID: 19336042 PMCID: PMC3707797 DOI: 10.1016/j.bbapap.2009.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 01/06/2009] [Accepted: 01/07/2009] [Indexed: 11/26/2022]
Abstract
The genomes of many cyanobacteria contain the sequence for a small protein with a common "Domain of Unknown Function" grouped into the DUF683 protein family. While the biological function of DUF683 is still not known, their genomic location within nitrogen fixation clusters suggests that DUF683 proteins may play a role in the process. The diurnal cyanobacterium Cyanothece sp. PCC 51142 contains a gene for a protein that falls into the DUF683 family, cce_0567 (78 aa, 9.0 kDa). In an effort to elucidate the biochemical role DUF683 proteins may play in nitrogen fixation, we have determined the first crystal structure for a protein in this family, cce_0567, to 1.84 A resolution. Cce_0567 crystallized in space group P2(1) with two protein molecules and one Ni(2+) cation per asymmetric unit. The protein is composed of two alpha-helices, residues P11 to G41 (alpha1) and L49-E74 (alpha2), with the second alpha-helix containing a short 3(10)-helix (Y46-N48). A four-residue linker (L42-D45) between the helices allows them to form an anti-parallel bundle and cross over each other towards their termini. In solution it is likely that two molecules of cce_0567 form a rod-like dimer by the stacking interactions of approximately 1/2 of the protein. Histidine-36 is highly conserved in all known DUF683 proteins and the N2 nitrogen of the H36 side chain of each molecule in the dimer is coordinated with Ni(2+) in the crystal structure. The divalent cation Ni(2+) was titrated into (15)N-labeled cce_0567 and chemical shift perturbations were observed only in the (1)H-(15)N HSQC spectra for residues at, or near, the site of Ni(2+) binding observed in the crystal structure. There was no evidence for an increase in the size of cce_0567 upon binding Ni(2+), even in large molar excess of Ni(2+), indicating that a metal was not required for dimer formation. Circular dichroism spectroscopy indicated that cce_0567 was extremely robust, with a melting temperature of approximately 62 degrees C that was reversible.
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Affiliation(s)
- Garry W Buchko
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
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Danielache SO, Eskebjerg C, Johnson MS, Ueno Y, Yoshida N. High-precision spectroscopy of32S,33S, and34S sulfur dioxide: Ultraviolet absorption cross sections and isotope effects. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd009695] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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38
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Mozaffarieh M, Grieshaber M, Orgül S, Flammer J. The Potential Value of Natural Antioxidative Treatment in Glaucoma. Surv Ophthalmol 2008; 53:479-505. [DOI: 10.1016/j.survophthal.2008.06.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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39
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Abstract
Mitochondrial respiration is responsible for more than 90% of oxygen consumption in humans. Cells utilize oxygen as the final electron acceptor in the aerobic metabolism of glucose to generate ATP which fuels most active cellular processes. Consequently, a drop in tissue oxygen levels to the point where oxygen demand exceeds supply (termed hypoxia) leads rapidly to metabolic crisis and represents a severe threat to ongoing physiological function and ultimately, viability. Because of the central role of oxygen in metabolism, it is perhaps not surprising that we have evolved an efficient and rapid molecular response system which senses hypoxia in cells, leading to the induction of an array of adaptive genes which facilitate increased oxygen supply and support anaerobic ATP generation. This response is governed by HIF (hypoxia-inducible factor). The oxygen sensitivity of this pathway is conferred by a family of hydroxylases which repress HIF activity in normoxia allowing its rapid activation in hypoxia. Because of its importance in a diverse range of disease states, the mechanism by which cells sense hypoxia and transduce a signal to the HIF pathway is an area of intense investigation. Inhibition of mitochondrial function reverses hypoxia-induced HIF leading to speculation of a role for mitochondria in cellular oxygen sensing. However, the nature of the signal between mitochondria and oxygen-sensing hydroxylase enzymes has remained controversial. In the present review, two models of the role for mitochondria in oxygen sensing will be discussed and recent evidence will be presented which raises the possibility that these two models which implicate ROS (reactive oxygen species) and oxygen redistribution respectively may complement each other and facilitate rapid and dynamic activation of the HIF pathway in hypoxia.
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Abstract
There are growing indications that life began in a radioactive beach environment. A geologic framework for the origin or support of life in a Hadean heavy mineral placer beach has been developed, based on the unique chemical properties of the lower-electronic actinides, which act as nuclear fissile and fertile fuels, radiolytic energy sources, oligomer catalysts, and coordinating ions (along with mineralogically associated lanthanides) for prototypical prebiotic homonuclear and dinuclear metalloenzymes. A four-factor nuclear reactor model was constructed to estimate how much uranium would have been required to initiate a sustainable fission reaction within a placer beach sand 4.3 billion years ago. It was calculated that about 1-8 weight percent of the sand would have to have been uraninite, depending on the weight percent, uranium enrichment, and quantity of neutron poisons present within the remaining placer minerals. Radiolysis experiments were conducted with various solvents with the use of uraniumand thorium-rich minerals (metatorbernite and monazite, respectively) as proxies for radioactive beach sand in contact with different carbon, hydrogen, oxygen, and nitrogen reactants. Radiation bombardment ranged in duration of exposure from 3 weeks to 6 months. Low levels of acetonitrile (estimated to be on the order of parts per billion in concentration) were conclusively identified in 2 setups and tentatively indicated in a 3(rd) by gas chromatography/mass spectrometry. These low levels have been interpreted within the context of a Hadean placer beach prebiotic framework to demonstrate the promise of investigating natural nuclear reactors as power production sites that might have assisted the origins of life on young rocky planets with a sufficiently differentiated crust/mantle structure. Future investigations are recommended to better quantify the complex relationships between energy release, radioactive grain size, fissionability, reactant phase, phosphorus release, and possible abiotic production of sugars, amino acids, activated phosphorus, prototypical organometallic enzymes, and oligomer catalysts at a single putative beach site.
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Affiliation(s)
- Zachary Adam
- Department of Aeronautics & Astronautics Engineering, and UW Center for Astrobiology, University of Washington, Seattle, Washington 98195-2400, USA.
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Kiang NY, Segura A, Tinetti G, Blankenship RE, Cohen M, Siefert J, Crisp D, Meadows VS. Spectral signatures of photosynthesis. II. Coevolution with other stars and the atmosphere on extrasolar worlds. ASTROBIOLOGY 2007; 7:252-74. [PMID: 17407410 DOI: 10.1089/ast.2006.0108] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take previously simulated planetary atmospheric compositions for Earth-like planets around observed F2V and K2V, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. With a line-by-line radiative transfer model, we calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the near-infrared, in bands at 0.93-1.1 microm, 1.1-1.4 microm, 1.5-1.8 microm, and 1.8-2.5 microm. However, underwater organisms will be restricted to wavelengths shorter than 1.4 microm and more likely below 1.1 microm. M star planets without oxygenic photosynthesis will have photon fluxes above 1.6 microm curtailed by methane. Longer-wavelength, multi-photo-system series would reduce the quantum yield but could allow for oxygenic photosystems at longer wavelengths. A wavelength of 1.1 microm is a possible upper cutoff for electronic transitions versus only vibrational energy; however, this cutoff is not strict, since such energetics depend on molecular configuration. M star planets could be a half to a tenth as productive as Earth in the visible, but exceed Earth if useful photons extend to 1.1 microm for anoxygenic photosynthesis. Under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth.
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Affiliation(s)
- Nancy Y Kiang
- NASA Goddard Institute for Space Studies, New York, New York 10025, USA.
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Goldblatt C, Lenton TM, Watson AJ. Bistability of atmospheric oxygen and the Great Oxidation. Nature 2006; 443:683-6. [PMID: 17036001 DOI: 10.1038/nature05169] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 08/14/2006] [Indexed: 11/09/2022]
Abstract
The history of the Earth has been characterized by a series of major transitions separated by long periods of relative stability. The largest chemical transition was the 'Great Oxidation', approximately 2.4 billion years ago, when atmospheric oxygen concentrations rose from less than 10(-5) of the present atmospheric level (PAL) to more than 0.01 PAL, and possibly to more than 0.1 PAL. This transition took place long after oxygenic photosynthesis is thought to have evolved, but the causes of this delay and of the Great Oxidation itself remain uncertain. Here we show that the origin of oxygenic photosynthesis gave rise to two simultaneously stable steady states for atmospheric oxygen. The existence of a low-oxygen (less than 10(-5) PAL) steady state explains how a reducing atmosphere persisted for at least 300 million years after the onset of oxygenic photosynthesis. The Great Oxidation can be understood as a switch to the high-oxygen (more than 5 x 10(-3) PAL) steady state. The bistability arises because ultraviolet shielding of the troposphere by ozone becomes effective once oxygen levels exceed 10(-5) PAL, causing a nonlinear increase in the lifetime of atmospheric oxygen. Our results indicate that the existence of oxygenic photosynthesis is not a sufficient condition for either an oxygen-rich atmosphere or the presence of an ozone layer, which has implications for detecting life on other planets using atmospheric analysis and for the evolution of multicellular life.
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Affiliation(s)
- Colin Goldblatt
- School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
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Ohmoto H, Watanabe Y, Ikemi H, Poulson SR, Taylor BE. Sulphur isotope evidence for an oxic Archaean atmosphere. Nature 2006; 442:908-11. [PMID: 16929296 DOI: 10.1038/nature05044] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Accepted: 07/10/2006] [Indexed: 11/08/2022]
Abstract
The presence of mass-independently fractionated sulphur isotopes (MIF-S) in many sedimentary rocks older than approximately 2.4 billion years (Gyr), and the absence of MIF-S in younger rocks, has been considered the best evidence for a dramatic change from an anoxic to oxic atmosphere around 2.4 Gyr ago. This is because the only mechanism known to produce MIF-S has been ultraviolet photolysis of volcanic sulphur dioxide gas in an oxygen-poor atmosphere. Here we report the absence of MIF-S throughout approximately 100-m sections of 2.76-Gyr-old lake sediments and 2.92-Gyr-old marine shales in the Pilbara Craton, Western Australia. We propose three possible interpretations of the MIF-S geologic record: (1) the level of atmospheric oxygen fluctuated greatly during the Archaean era; (2) the atmosphere has remained oxic since approximately 3.8 Gyr ago, and MIF-S in sedimentary rocks represents times and regions of violent volcanic eruptions that ejected large volumes of sulphur dioxide into the stratosphere; or (3) MIF-S in rocks was mostly created by non-photochemical reactions during sediment diagenesis, and thus is not linked to atmospheric chemistry.
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Affiliation(s)
- Hiroshi Ohmoto
- NASA Astrobiology Institute and Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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Olson JM. Photosynthesis in the Archean era. PHOTOSYNTHESIS RESEARCH 2006; 88:109-17. [PMID: 16453059 DOI: 10.1007/s11120-006-9040-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Accepted: 01/08/2006] [Indexed: 05/06/2023]
Abstract
The earliest reductant for photosynthesis may have been H2. The carbon isotope composition measured in graphite from the 3.8-Ga Isua Supercrustal Belt in Greenland is attributed to H2-driven photosynthesis, rather than to oxygenic photosynthesis as there would have been no evolutionary pressure for oxygenic photosynthesis in the presence of H2. Anoxygenic photosynthesis may also be responsible for the filamentous mats found in the 3.4-Ga Buck Reef Chert in South Africa. Another early reductant was probably H2S. Eventually the supply of H2 in the atmosphere was likely to have been attenuated by the production of CH4 by methanogens, and the supply of H2S was likely to have been restricted to special environments near volcanos. Evaporites, possible stromatolites, and possible microfossils found in the 3.5-Ga Warrawoona Megasequence in Australia are attributed to sulfur-driven photosynthesis. Proteobacteria and protocyanobacteria are assumed to have evolved to use ferrous iron as reductant sometime around 3.0 Ga or earlier. This type of photosynthesis could have produced banded iron formations similar to those produced by oxygenic photosynthesis. Microfossils, stromatolites, and chemical biomarkers in Australia and South Africa show that cyanobacteria containing chlorophyll a and carrying out oxygenic photosynthesis appeared by 2.8 Ga, but the oxygen level in the atmosphere did not begin to increase until about 2.3 Ga.
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Affiliation(s)
- John M Olson
- Department of Biochemistry and Molecular Biology, 913 Lederle GRT Tower-B, University of Massachusetts Amherst, Amherst, MA 01003-9305, USA.
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45
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Abstract
Recent studies using geological and molecular phylogenetic evidence suggest several alternative evolutionary scenarios for the origin of photosynthesis. The earliest photosynthetic group is variously thought to be heliobacteria, proteobacteria or a precursor of cyanobacteria, organisms whose photosynthetic pigments make them different colors.
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Affiliation(s)
- Jin Xiong
- Department of Biology, Texas A&M University, College Station, TX 77843, USA.
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46
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Barr H. Photodynamic Therapy for High-Grade Dysplasia in Barrett’s Esophagus. TECHNIQUES IN GASTROINTESTINAL ENDOSCOPY 2005. [DOI: 10.1016/j.tgie.2005.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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47
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Farquhar J, Wing BA. The terrestrial record of stable sulphur isotopes: a review of the implications for evolution of Earth’s sulphur cycle. ACTA ACUST UNITED AC 2005. [DOI: 10.1144/gsl.sp.2005.248.01.09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractThe observation of anomalous (non mass-dependent) sulphur isotope compositions in Archaean and early Proterozoic rocks but not in rocks younger than approximately 2 Ga has been interpreted to reflect fundamental change in the terrestrial sulphur cycle, in atmospheric chemistry, and in atmospheric oxygen content. Similar non mass-dependent sulphur isotope compositions in present-day samples (atmospheric aerosols and ice-core horizons containing remnants of stratosphere-piercing volcanic eruptions) are interpreted to carry information about modern atmospheric chemistry and transport. The interpretation of these observations hinges on our understanding of the processes that produce non mass-dependent sulphur isotope compositions, the processes that transport and transfer the isotopic signals throughout the sulphur cycle, and the processes that act to preserve or erase these isotopic signals once they are established. The growing dataset and hypotheses related to non mass-dependent sulphur are evaluated, emphasizing that which remains to be learned about the evolution of the record, the compositions of key reservoirs, and the transfer of the signal from the atmosphere to the surface and ultimately to the deep Earth.
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Affiliation(s)
- James Farquhar
- Earth System Science Interdisciplinary Center and Department of Geology, University of Maryland
College Park, Maryland 20742
| | - Boswell A. Wing
- Earth System Science Interdisciplinary Center and Department of Geology, University of Maryland
College Park, Maryland 20742
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Abstract
Comparative physiology has proven a powerful approach to our understanding of how animals function under hypoxic conditions and to identifying potential adaptations to environmental oxygen levels. This review considers the potential for using a similar comparative approach with functional genomics to understand the genetic basis of such physiological processes and evolutionary adaptations. Comparative functional genomics is currently limited by genome data, which are available for only a few model organisms. However, comparative studies between model organisms of the same species having slightly different genomes (e.g., in-bred strains of laboratory rodents, transgenic mice, and consomic rats) demonstrate the types of results, as well as the analytical challenges, that are possible if comparative functional genomics is applied to more species. Results from wild and domestic animal studies suggest new models to investigate physiological and evolutionary responses to oxygen levels with functional genomics.
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Affiliation(s)
- Frank L Powell
- Department of Medicine and White Mountain Research Station, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92037-0623, USA.
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49
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Rees DC, Howard JB. The interface between the biological and inorganic worlds: iron-sulfur metalloclusters. Science 2003; 300:929-31. [PMID: 12738849 DOI: 10.1126/science.1083075] [Citation(s) in RCA: 180] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Complex iron-sulfur metalloclusters form the active sites of the enzymes that catalyze redox transformations of N2, CO, and H2, which are likely components of Earth's primordial atmosphere. Although these centers reflect the organizational principles of simpler iron-sulfur clusters, they exhibit extensive elaborations that confer specific ligand-binding and catalytic properties. These changes were probably achieved through evolutionary processes, including the fusion of small clusters, the addition of new metals, and the development of cluster assembly pathways, driven by selective pressures resulting from changes in the chemical composition of the biosphere.
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Affiliation(s)
- Douglas C Rees
- Division of Chemistry and Chemical Engineering 114-96, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
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50
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Berman-Frank I, Lundgren P, Falkowski P. Nitrogen fixation and photosynthetic oxygen evolution in cyanobacteria. Res Microbiol 2003; 154:157-64. [PMID: 12706503 DOI: 10.1016/s0923-2508(03)00029-9] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The biological reduction of N(2) is catalyzed by nitrogenase, which is irreversibly inhibited by molecular oxygen. Cyanobacteria are the only diazotrophs (nitrogen-fixing organisms) that produce oxygen as a by-product of the photosynthetic process, and which must negotiate the inevitable presence of molecular oxygen with an essentially anaerobic enzyme. In this review, we present an analysis of the geochemical conditions under which nitrogenase evolved and examine how the evolutionary history of the enzyme complex corresponds to the physiological, morphological, and developmental strategies for reducing damage by molecular oxygen. Our review highlights biogeochemical constraints on diazotrophic cyanobacteria in the contemporary world.
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Affiliation(s)
- Ilana Berman-Frank
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Rd., New Brunswick, NJ 08901, USA.
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