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Vermeij GJ. The illusion of balance in the history of the biosphere. GEOBIOLOGY 2024; 22:e12584. [PMID: 38385604 DOI: 10.1111/gbi.12584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 12/15/2023] [Accepted: 01/03/2024] [Indexed: 02/23/2024]
Abstract
Earth's surface has been irreversibly altered by the activity of organisms, a process that has accelerated as the power of the biosphere (the rate at which life extracts and deploys energy) has increased over time. This trend is incompatible with the expectation that the inputs to Earth's surface of life's materials from the crust and mantle be matched by export from Earth's surface to long-term reservoirs. Here, I suggest that the collective activity of organisms has always violated this balance. The biosphere's ability to extract, retain, recycle, and accumulate materials has allowed living biomass to increase and for exports to decrease over very long timescales. This collective metabolism implies a net transfer of materials from the planet's interior to its surface. The combination of metabolic innovations, competition, adaptive evolution, and the establishment of collaborative economic feedback in ecosystems created dynamic ecological stability despite great spatial and temporal heterogeneity in physical and biological inputs and export of nutrients into and out of the biosphere. Models of geochemical cycling must take the fundamental role of living organisms and the evolutionary changes in these roles into account to explain past and future conditions.
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Mather CC, Lampinen HM, Tucker M, Leopold M, Dogramaci S, Raven M, Gilkes RJ. Microbial influence on dolomite and authigenic clay mineralisation in dolocrete profiles of NW Australia. GEOBIOLOGY 2023; 21:644-670. [PMID: 36973880 DOI: 10.1111/gbi.12555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/02/2023] [Accepted: 03/12/2023] [Indexed: 06/18/2023]
Abstract
Dolomite (CaMg(CO3 )2 ) precipitation is kinetically inhibited at surface temperatures and pressures. Experimental studies have demonstrated that microbial extracellular polymeric substances (EPS) as well as certain clay minerals may catalyse dolomite precipitation. However, the combined association of EPS with clay minerals and dolomite and their occurrence in the natural environment are not well documented. We investigated the mineral and textural associations within groundwater dolocrete profiles from arid northwest Australia. Microbial EPS is a site of nucleation for both dolomite and authigenic clay minerals in this Late Miocene to Pliocene dolocrete. Dolomite crystals are commonly encased in EPS alveolar structures, which have been mineralised by various clay minerals, including montmorillonite, trioctahedral smectite and palygorskite-sepiolite. Observations of microbial microstructures and their association with minerals resemble textures documented in various lacustrine and marine microbialites, indicating that similar mineralisation processes may have occurred to form these dolocretes. EPS may attract and bind cations that concentrate to form the initial particles for mineral nucleation. The dolomite developed as nanocrystals, likely via a disordered precursor, which coalesced to form larger micritic crystal aggregates and rhombic crystals. Spheroidal dolomite textures, commonly with hollow cores, are also present and may reflect the mineralisation of a biofilm surrounding coccoid bacterial cells. Dolomite formation within an Mg-clay matrix is also observed, more commonly within a shallow pedogenic horizon. The ability of the negatively charged surfaces of clay and EPS to bind and dewater Mg2+ , as well as the slow diffusion of ions through a viscous clay or EPS matrix, may promote the incorporation of Mg2+ into the mineral and overcome the kinetic effects to allow disordered dolomite nucleation and its later growth. The results of this study show that the precipitation of clay and carbonate minerals in alkaline environments may be closely associated and can develop from the same initial amorphous Ca-Mg-Si-rich matrix within EPS. The abundance of EPS preserved within the profiles is evidence of past microbial activity. Local fluctuations in chemistry, such as small increases in alkalinity, associated with the degradation of EPS or microbial activity, were likely important for both clay and dolomite formation. Groundwater environments may be important and hitherto understudied settings for microbially influenced mineralisation and for low-temperature dolomite precipitation.
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Affiliation(s)
- Caroline C Mather
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- School of Social Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Heta M Lampinen
- Commonwealth Scientific and Industrial Research Organisation, Mineral Resources, 26 Dick Perry Avenue, Kensington, Western Australia, 6151, Australia
| | - Maurice Tucker
- School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK
| | - Matthias Leopold
- UWA-School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Shawan Dogramaci
- School of Earth Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- National Centre for Groundwater Research and Training & College of Science and Engineering, Flinders University, Adelaide, South Australia, 5042, Australia
| | - Mark Raven
- Commonwealth Scientific and Industrial Research Organisation, Mineralogical Services, Waite Campus, Urrbrae, South Australia, 5064, Australia
| | - Robert J Gilkes
- UWA-School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
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Ibarra Y, Sanon S. A freshwater analog for the production of Epiphyton-like microfossils. GEOBIOLOGY 2019; 17:510-522. [PMID: 31002215 DOI: 10.1111/gbi.12341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 06/09/2023]
Abstract
Calcified microbial microfossils-often interpreted as cyanobacteria-were important components of Precambrian and Paleozoic limestones, but their paucity in modern marine environments complicates our ability to make conclusive interpretations about their taxonomic affinity and geologic significance. Freshwater spring-associated limestones (e.g., travertine and tufa) serve as terrestrial analogs to investigate mineralization in and around aquatic biofilms on observable timescales. We document the diagenesis of calcite fabrics associated with the freshwater algae Oocardium stratum, an epiphytic colonial green algae (desmid) known for producing stalks of extracellular polymeric substances (EPS) and passively producing a bifurcating tubular calcite monocrystal. Bifurcating EPS stalks produced by Oocardium colonies can become calcified and preserved in ancient carbonate deposits. Calcified micritic EPS stalks have a filamentous morphology, show evidence of branching, and maintain uniformity in diameter thickness throughout the mm-scale colony, much like the enigmatic calcimicrobe Epiphyton. We provide a mechanism by which calcification associated with a colonial semispherical micro-organism produces microfossils that deceptively resemble filamentous forms. These findings have implications for the use of morphological traits when assigning taxonomic affinities to extinct microfossil groups and highlight the utility of calcifying freshwater modern environments to investigate microbial taphonomy.
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Affiliation(s)
- Yadira Ibarra
- Department of Earth and Climate Sciences, San Francisco State University, San Francisco, California
| | - Sonicah Sanon
- Department of Earth and Climate Sciences, San Francisco State University, San Francisco, California
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McMahon S, Bosak T, Grotzinger JP, Milliken RE, Summons RE, Daye M, Newman SA, Fraeman A, Williford KH, Briggs DEG. A Field Guide to Finding Fossils on Mars. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2018; 123:1012-1040. [PMID: 30034979 PMCID: PMC6049883 DOI: 10.1029/2017je005478] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/28/2018] [Accepted: 04/23/2018] [Indexed: 05/05/2023]
Abstract
The Martian surface is cold, dry, exposed to biologically harmful radiation and apparently barren today. Nevertheless, there is clear geological evidence for warmer, wetter intervals in the past that could have supported life at or near the surface. This evidence has motivated National Aeronautics and Space Administration and European Space Agency to prioritize the search for any remains or traces of organisms from early Mars in forthcoming missions. Informed by (1) stratigraphic, mineralogical and geochemical data collected by previous and current missions, (2) Earth's fossil record, and (3) experimental studies of organic decay and preservation, we here consider whether, how, and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early Mars. We conclude that Noachian-Hesperian Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits, especially where enriched in silica, currently represent the most promising and best understood astropaleontological targets. Siliceous sinters would also be an excellent target, but their presence on Mars awaits confirmation. More work is needed to improve our understanding of fossil preservation in the context of other environments specific to Mars, particularly within evaporative salts and pore/fracture-filling subsurface minerals.
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Affiliation(s)
- S. McMahon
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
- UK Centre for Astrobiology, School of Physics and AstronomyUniversity of EdinburghEdinburghUK
| | - T. Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - J. P. Grotzinger
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
| | - R. E. Milliken
- Department of Earth, Environmental and Planetary SciencesBrown UniversityProvidenceRIUSA
| | - R. E. Summons
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - M. Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - S. A. Newman
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - A. Fraeman
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. H. Williford
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. E. G. Briggs
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
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Gomes ML, Fike DA, Bergmann KD, Jones C, Knoll AH. Environmental insights from high-resolution (SIMS) sulfur isotope analyses of sulfides in Proterozoic microbialites with diverse mat textures. GEOBIOLOGY 2018; 16:17-34. [PMID: 29047210 DOI: 10.1111/gbi.12265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
In modern microbial mats, hydrogen sulfide shows pronounced sulfur isotope (δ34 S) variability over small spatial scales (~50‰ over <4 mm), providing information about microbial sulfur cycling within different ecological niches in the mat. In the geological record, the location of pyrite formation, overprinting from mat accretion, and post-depositional alteration also affect both fine-scale δ34 S patterns and bulk δ34 Spyrite values. We report μm-scale δ34 S patterns in Proterozoic samples with well-preserved microbial mat textures. We show a well-defined relationship between δ34 S values and sulfide mineral grain size and type. Small pyrite grains (<25 μm) span a large range, tending toward high δ34 S values (-54.5‰ to 11.7‰, mean: -14.4‰). Larger pyrite grains (>25 μm) have low but equally variable δ34 S values (-61.0‰ to -10.5‰, mean: -44.4‰). In one sample, larger sphalerite grains (>35 μm) have intermediate and essentially invariant δ34 S values (-22.6‰ to -15.6‰, mean: -19.4‰). We suggest that different sulfide mineral populations reflect separate stages of formation. In the first stage, small pyrite grains form near the mat surface along a redox boundary where high rates of sulfate reduction, partial closed-system sulfate consumption in microenvironments, and/or sulfide oxidation lead to high δ34 S values. In another stage, large sphalerite grains with low δ34 S values grow along the edges of pore spaces formed from desiccation of the mat. Large pyrite grains form deeper in the mat at slower sulfate reduction rates, leading to low δ34 Ssulfide values. We do not see evidence for significant 34 S-enrichment in bulk pore water sulfide at depth in the mat due to closed-system Rayleigh fractionation effects. On a local scale, Rayleigh fractionation influences the range of δ34 S values measured for individual pyrite grains. Fine-scale analyses of δ34 Spyrite patterns can thus be used to extract environmental information from ancient microbial mats and aid in the interpretation of bulk δ34 Spyrite records.
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Affiliation(s)
- M L Gomes
- Washington University, Saint Louis, MO, USA
- Harvard University, Cambridge, MA, USA
| | - D A Fike
- Washington University, Saint Louis, MO, USA
| | - K D Bergmann
- Massachusettes Institute of Technology, Cambridge, MA, USA
| | - C Jones
- Washington University, Saint Louis, MO, USA
| | - A H Knoll
- Harvard University, Cambridge, MA, USA
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Cyanobacterial exopolymer properties differentiate microbial carbonate fabrics. Sci Rep 2017; 7:11805. [PMID: 28924251 PMCID: PMC5603507 DOI: 10.1038/s41598-017-12303-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/07/2017] [Indexed: 02/01/2023] Open
Abstract
Although environmental changes and evolution of life are potentially recorded via microbial carbonates, including laminated stromatolites and clotted thrombolites, factors controlling their fabric are still a matter of controversy. Herein, we report that the exopolymer properties of different cyanobacterial taxa primarily control the microbial carbonates fabrics in modern examples. This study shows that the calcite encrustation of filamentous Phormidium sp. secreting acidic exopolymers forms the laminated fabric of stromatolites, whereas the encrustation of coccoid Coelosphaeriopsis sp. secreting acidic exopolymers and poor calcification of filamentous Leptolyngbya sp. secreting non-acidic exopolymers form peloids and fenestral structures, respectively, i.e. the clotted fabric of thrombolites. Based on these findings, we suggest that the rise and decline of cyanobacteria possessing different exopolymer properties caused the expansion of thrombolites around the Proterozoic/Cambrian boundary.
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Foucher F, Westall F. Raman imaging of metastable opal in carbonaceous microfossils of the 700-800 ma old Draken Formation. ASTROBIOLOGY 2013; 13:57-67. [PMID: 23276206 DOI: 10.1089/ast.2012.0889] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Opaline silica was detected, with Raman spectroscopy, in carbonaceous microfossils (especially Myxococcoides) in silicified filamentous microbial mats within dolomitized conglomerates of the Draken Formation (-800 to -700 Ma). High-resolution electron microscopy (HRTEM) and microprobe analyses were used to confirm the nature of this phase in the quartz matrix of the microbial mats. The silica likely precipitated in a microcrystalline form onto the organic macromolecules around, and within, the degrading microorganisms and preserved them by inhibiting the natural phase change to quartz. The Raman signal of opaline silica associated with carbonaceous matter and other biosignatures could be a potential indicator of biogenicity. This kind of association could be very useful during the future ExoMars mission (ESA/Roscosmos, 2018) that will search for traces of past life on Mars.
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Affiliation(s)
- Frédéric Foucher
- Centre de Biophysique Moléculaire, UPR CNRS 4301, Orléans, France.
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Arp G, Bissett A, Brinkmann N, Cousin S, De Beer D, Friedl T, Mohr KI, Neu TR, Reimer A, Shiraishi F, Stackebrandt E, Zippel B. Tufa-forming biofilms of German karstwater streams: microorganisms, exopolymers, hydrochemistry and calcification. ACTA ACUST UNITED AC 2010. [DOI: 10.1144/sp336.6] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractTo understand mechanisms of tufa biofilm calcification, selected karstwater stream stromatolites in Germany have been investigated with regard to their hydrochemistry, biofilm community, exopolymers, physicochemical microgradients, calcification pattern and lamination. In stream waters, CO2 degassing drives the increase in calcite saturation to maximum values of approximately 10-fold, independent from the initial Ca2+/alkalinity ratio. For the cyanobacteria of tufa biofilms, a culture-independent molecular approach showed that microscopy of resin-embedded biofilm thin sections underestimated the actual diversity of cyanobacteria, i.e. the six cyanobacteria morphotypes were opposed to nine different lineages of the 16S rDNA phylogeny. The same morphotype may even represent two genetically distant cyanobacteria and the closest relatives of tufa biofilm cyanobacteria may be from quite different habitats. Diatom diversity was even higher in the biofilm at the studied exemplar site than that of the cyanobacteria, i.e. 13 diatom species opposed to 9 cyanobacterial lineages. The non-phototrophic prokaryotic biofilm community is clearly different from the soil-derived community of the stream waters, and largely composed of flavobacteria, firmicutes, proteobacteria and actinobacteria. The exopolymeric biofilm matrix can be divided into three structural domains by fluorescence lectin-binding analysis. Seasonal and spatial variability of these structural EPS domains is low in the investigated streams. As indicated by microsensor data, biofilm photosynthesis is the driving mechanism in tufa stromatolite formation. However, photosynthesis-induced biofilm calcification accounts for only 10–20% of the total Ca2+ loss in the streams, and occurs in parallel to inorganic precipitation driven by CO2-degassing within the water column and on biofilm-free surfaces. Annual stromatolite laminae reflect seasonal changes in temperature and light supply. The stable carbon isotope composition of the laminae is not affected by photosynthesis-induced microgradients, but mirrors that of the bulk water body only reflecting climate fluctuations. Tufa stromatolites with their cyanobacterial–photosynthesis-related calcification fabrics form an analogue to porostromate cyanobacterial stromatolites in fossil settings high in CaCO3 mineral supersaturation but comparatively low in dissolved inorganic carbon. Here, the sum-effect of heterotrophic exopolymer-degradation and secondary Ca2+-release rather decreases calcite saturation, contrary to settings high in dissolved inorganic carbon such as soda lakes.
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Affiliation(s)
- Gernot Arp
- University of Göttingen, Geoscience Centre, Goldschmidtstraße 3, D-37077 Göttingen, Germany
| | - Andrew Bissett
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, D-28359 Bremen, Germany
- Present address: CSIRO, Plant Industry, P. O. Box 1600, Canberra, ACT 2601, Australia
| | - Nicole Brinkmann
- University of Göttingen, Albrecht-von-Haller-Institute for Plant Sciences, Experimental Phycology and Culture Collection of Algae (SAG), Nikolausberger Weg 18, D-37073 Göttingen
| | - Sylvie Cousin
- German Collection of Microorganisms and Cell Cultures DSMZ, Inhoffenstraße 7 B, D-38124 Braunschweig, Germany
- Institut Pasteur, Genopole de l'Ile de France, PF1, Paris, France
| | - Dirk De Beer
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, D-28359 Bremen, Germany
| | - Thomas Friedl
- University of Göttingen, Albrecht-von-Haller-Institute for Plant Sciences, Experimental Phycology and Culture Collection of Algae (SAG), Nikolausberger Weg 18, D-37073 Göttingen
| | - Kathrin I. Mohr
- University of Göttingen, Albrecht-von-Haller-Institute for Plant Sciences, Experimental Phycology and Culture Collection of Algae (SAG), Nikolausberger Weg 18, D-37073 Göttingen
- Present address: Helmholtz Centre for Infection Research, Inhoffenstraße 7, D-38124 Braunschweig, Germany
| | - Thomas R. Neu
- Helmholtz Centre for Environmental Research UFZ, Department of River Ecology, Brückstraße 3a, D-39114 Magdeburg, Germany
| | - Andreas Reimer
- University of Göttingen, Geoscience Centre, Goldschmidtstraße 3, D-37077 Göttingen, Germany
| | - Fumito Shiraishi
- University of Göttingen, Geoscience Centre, Goldschmidtstraße 3, D-37077 Göttingen, Germany
- Present address: Division of Evolution of Earth Environment, Graduate School of Social and Cultural Studies, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Erko Stackebrandt
- German Collection of Microorganisms and Cell Cultures DSMZ, Inhoffenstraße 7 B, D-38124 Braunschweig, Germany
| | - Barbara Zippel
- Helmholtz Centre for Environmental Research UFZ, Department of River Ecology, Brückstraße 3a, D-39114 Magdeburg, Germany
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Planavsky N, Reid RP, Lyons TW, Myshrall KL, Visscher PT. Formation and diagenesis of modern marine calcified cyanobacteria. GEOBIOLOGY 2009; 7:566-576. [PMID: 19796131 DOI: 10.1111/j.1472-4669.2009.00216.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Calcified cyanobacterial microfossils are common in carbonate environments through most of the Phanerozoic, but are absent from the marine rock record over the past 65 Myr. There has been long-standing debate on the factors controlling the formation and temporal distribution of these fossils, fostered by the lack of a suitable modern analog. We describe calcified cyanobacteria filaments in a modern marine reef setting at Highborne Cay, Bahamas. Our observations and stable isotope data suggest that initial calcification occurs in living cyanobacteria and is photosynthetically induced. A single variety of cyanobacteria, Dichothrix sp., produces calcified filaments. Adjacent cyanobacterial mats form well-laminated stromatolites, rather than calcified filaments, indicating there can be a strong taxonomic control over the mechanism of microbial calcification. Petrographic analyses indicate that the calcified filaments are degraded during early diagenesis and are not present in well-lithified microbialites. The early diagenetic destruction of calcified filaments at Highborne Cay indicates that the absence of calcified cyanobacteria from periods of the Phanerozoic is likely to be caused by low preservation potential as well as inhibited formation.
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Affiliation(s)
- N Planavsky
- Rosenstiel School of Marine and Atmospheric Sciences, Miami, FL, USA.
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Halverson GP, Hurtgen MT, Porter SM, Collins AS. Chapter 10 Neoproterozoic-Cambrian Biogeochemical Evolution. NEOPROTEROZOIC-CAMBRIAN TECTONICS, GLOBAL CHANGE AND EVOLUTION: A FOCUS ON SOUTH WESTERN GONDWANA 2009. [DOI: 10.1016/s0166-2635(09)01625-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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MEI M. Revised Classification of Microbial Carbonates: Complementing the Classification of Limestones. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/s1872-5791(07)60044-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Cavalazzi B. Chemotrophic filamentous microfossils from the Hollard Mound (Devonian, Morocco) as investigated by focused ion beam. ASTROBIOLOGY 2007; 7:402-15. [PMID: 17480168 DOI: 10.1089/ast.2005.0398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The biologic origin of objects with microbe-like morphologies from the oldest preserved terrestrial sedimentary rocks remains a matter of controversy. Their biogenicity has been questioned, as well as the claim that they are convincing evidence of early life. Though minerals with microbe-like morphologies represent ambiguous evidence of life, they are, in a number of conditions, the only achievable information. In this study, the focused ion beam (FIB) electron microscopy technique was used for nano and micrometer-scale high-resolution imaging and in situ microsectioning of filamentous microfossils. The structural elements of these filaments, their spatial relationships with the host rock, and artifacts produced by alteration of the original morphology due to laboratory sample processing have been clearly defined. The in situ sectioning provided a means by which to investigate surface and subsurface microstructures and perform different analytical techniques on the same object, which minimizes sample destruction and avoids excessive manual handling and exposure of the specimen during analysis. Improvement in the morphological and compositional evaluation of the filaments has facilitated the development of a hypothesis regarding the metabolic pathway of the filamentous microfossils preserved in the Middle Devonian-aged Hollard Mound deposit, Anti-Atlas, Morocco. The results of this study demonstrate the potential of the FIB/SEM (scanning electron microscopy) system for detecting microbial-scale morphologies.
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Affiliation(s)
- Barbara Cavalazzi
- Dipartimento di Scienze della Terra e Geologico-Ambientali, Universitá di Bologna, Bologna, Italy.
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Arp G, Reimer A, Reitner J. Photosynthesis-induced biofilm calcification and calcium concentrations in Phanerozoic oceans. Science 2001; 292:1701-4. [PMID: 11387471 DOI: 10.1126/science.1057204] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Photosynthetic carbon assimilation is commonly invoked as the cause of calcium carbonate precipitation in cyanobacterial biofilms that results in the formation of calcareous stromatolites. However, biofilm calcification patterns in recent lakes and simulation of photosynthetically induced rise in calcium carbonate supersaturation demonstrate that this mechanism applies only in settings low in dissolved inorganic carbon and high in calcium. Taking into account paleo-partial pressure curves for carbon dioxide, we show that Phanerozoic oceans sustaining calcified cyanobacteria must have had considerably higher calcium concentrations than oceans of today. In turn, the enigmatic lack of calcified cyanobacteria in stromatolite-bearing Precambrian sequences can now be explained as a result of high dissolved inorganic carbon concentrations.
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Affiliation(s)
- G Arp
- Göttinger Zentrum für Geowissenschaften, Abteilung Geobiologie, Universität Göttingen, Goldschmidtstrasse 3, D-37077 Göttingen, Germany.
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Marin F, Corstjens P, de Gaulejac B, de Vrind-De Jong E, Westbroek P. Mucins and molluscan calcification. Molecular characterization of mucoperlin, a novel mucin-like protein from the nacreous shell layer of the fan mussel Pinna nobilis (Bivalvia, pteriomorphia). J Biol Chem 2000; 275:20667-75. [PMID: 10770949 DOI: 10.1074/jbc.m003006200] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cDNA expression library constructed from mantle tissue mRNA of the Mediterranean fan mussel Pinna nobilis was screened with antibodies raised against the acetic acid-soluble shell matrix of the same species. This resulted in the isolation of a 2138-base pair cDNA, containing 13 tandem repeats of 93 base pairs. The deduced protein has a molecular mass of 66.7 kDa and a isoelectric point of 4.8. This protein, which is enriched in serine and proline residues, was overexpressed, purified, and used for producing polyclonal antibodies. Immunological in situ and in vitro tests showed that the protein is localized in the nacreous aragonitic layer of P. nobilis, but not in the calcitic prisms. Because this protein of the nacre of P. nobilis exhibits some mucin-like characteristics, we propose the name mucoperlin. This is the first paper reporting the cloning of a molluscan mucin and the first molecular evidence for the involvement of a mucin in molluscan calcification. This finding corroborates our previous hypothesis that some of the proteinaceous constituents of the molluscan shell matrix would derive from mucins, common to many metazoan lineages of the late Precambrian (Marin, F., Smith, M., Isa, Y., Muyzer, G. and Westbroek, P. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 1554-1559). The adaptation of an ancestral mucin to a new function, the regulation of the mineralization process, may be one of the molecular events, among others, that would explain the simultaneous emergence of organized calcification in many metazoan lineages during the Cambrian explosion.
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Affiliation(s)
- F Marin
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
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Westall F. The nature of fossil bacteria: A guide to the search for extraterrestrial life. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998je900051] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Grotzinger JP, Knoll AH. Stromatolites in Precambrian carbonates: evolutionary mileposts or environmental dipsticks? ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES 1999; 27:313-58. [PMID: 11543060 DOI: 10.1146/annurev.earth.27.1.313] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Stromatolites are attached, lithified sedimentary growth structures, accretionary away from a point or limited surface of initiation. Though the accretion process is commonly regarded to result from the sediment trapping or precipitation-inducing activities of microbial mats, little evidence of this process is preserved in most Precambrian stromatolites. The successful study and interpretation of stromatolites requires a process-based approach, oriented toward deconvolving the replacement textures of ancient stromatolites. The effects of diagenetic recrystallization first must be accounted for, followed by analysis of lamination textures and deduction of possible accretion mechanisms. Accretion hypotheses can be tested using numerical simulations based on modem stromatolite growth processes. Application of this approach has shown that stromatolites were originally formed largely through in situ precipitation of laminae during Archean and older Proterozoic times, but that younger Proterozoic stromatolites grew largely through the accretion of carbonate sediments, most likely through the physical process of microbial trapping and binding. This trend most likely reflects long-term evolution of the earth's environment rather than microbial communities.
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Affiliation(s)
- J P Grotzinger
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA.
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Affiliation(s)
- Rachel Wood
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom
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Abstract
Truth, goes an old proverb, is the daughter of time. Fifty years ago, G. G. Simpson (1944) brought paleontology into the Neodarwinian fold, arguing that evolutionary tempo can be documented in the geological record and used to inform debate about evolutionary mode. Today, increasingly sophisticated paleontological investigations of rate—be it diversification, extinction, migration, morphological change, or divergence in macromolecular sequence—require calibration of the geological time scale with a precision far greater than Simpson could have anticipated. Expanding research on the relationships between environmental history and evolution also requires unprecedented resolution in correlation and geochronometry.
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Affiliation(s)
- A H Knoll
- Botanical Museum, Harvard University, Cambridge, Massachusetts 02138, USA
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Logan GA, Hayes JM, Hieshima GB, Summons RE. Terminal Proterozoic reorganization of biogeochemical cycles. Nature 1995; 376:53-6. [PMID: 11536694 DOI: 10.1038/376053a0] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Proterozoic aeon (2,500-540 million years ago) saw episodic increases in atmospheric oxygen content, the evolution of multicellular life and, at its close, an enormous radiation of animal diversity. These profound biological and environmental changes must have been linked, but the underlying mechanisms have been obscure. Here we show that hydrocarbons extracted from Proterozoic sediments in several locations worldwide are derived mainly from bacteria or other heterotrophs rather than from photosynthetic organisms. Biodegradation of algal products in sedimenting matter was therefore unusually complete, indicating that organic material was extensively reworked as it sank slowly through the water column. We propose that a significant proportion of this reworking will have been mediated by sulphate-reducing bacteria, forming sulphide. The production of sulphide and consumption of oxygen near the ocean surface will have inhibited transport of O2 to the deep ocean. We find that preservation of algal-lipid skeletons improves at the beginning of the Cambrian, reflecting the increase in transport by rapidly sinking faecal pellets. We suggest that this rapid removal of organic matter will have increased oxygenation of surface waters, leading to a descent of the O2-sulphide interface to the sea floor and to marked changes in the marine environment, ultimately contributing to the Cambrian radiation.
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Affiliation(s)
- G A Logan
- Departments of Geological Sciences and of Chemistry, Indiana University, Bloomington 47405-1403, USA
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