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Aerts JW, Röling WFM, Elsaesser A, Ehrenfreund P. Biota and biomolecules in extreme environments on Earth: implications for life detection on Mars. Life (Basel) 2014; 4:535-65. [PMID: 25370528 PMCID: PMC4284457 DOI: 10.3390/life4040535] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/08/2014] [Accepted: 09/16/2014] [Indexed: 11/24/2022] Open
Abstract
The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions “what to look for”, “where to look”, and “how to look for it” require more of our attention to ensure the success of future life detection missions on Mars.
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Affiliation(s)
- Joost W Aerts
- Molecular Cell Physiology, Faculty of Earth and Life Sciences, VU University Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | - Wilfred F M Röling
- Molecular Cell Physiology, Faculty of Earth and Life Sciences, VU University Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | - Andreas Elsaesser
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands.
| | - Pascale Ehrenfreund
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands.
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Placing an upper limit on cryptic marine sulphur cycling. Nature 2014; 513:530-3. [PMID: 25209667 DOI: 10.1038/nature13698] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 07/16/2014] [Indexed: 12/22/2022]
Abstract
A quantitative understanding of sources and sinks of fixed nitrogen in low-oxygen waters is required to explain the role of oxygen-minimum zones (OMZs) in controlling the fixed nitrogen inventory of the global ocean. Apparent imbalances in geochemical nitrogen budgets have spurred numerous studies to measure the contributions of heterotrophic and autotrophic N2-producing metabolisms (denitrification and anaerobic ammonia oxidation, respectively). Recently, 'cryptic' sulphur cycling was proposed as a partial solution to the fundamental biogeochemical problem of closing marine fixed-nitrogen budgets in intensely oxygen-deficient regions. The degree to which the cryptic sulphur cycle can fuel a loss of fixed nitrogen in the modern ocean requires the quantification of sulphur recycling in OMZ settings. Here we provide a new constraint for OMZ sulphate reduction based on isotopic profiles of oxygen ((18)O/(16)O) and sulphur ((33)S/(32)S, (34)S/(32)S) in seawater sulphate through oxygenated open-ocean and OMZ-bearing water columns. When coupled with observations and models of sulphate isotope dynamics and data-constrained model estimates of OMZ water-mass residence time, we find that previous estimates for sulphur-driven remineralization and loss of fixed nitrogen from the oceans are near the upper limit for what is possible given in situ sulphate isotope data.
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53
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Fischer E, Martínez GM, Elliott HM, Rennó NO. Experimental evidence for the formation of liquid saline water on Mars. GEOPHYSICAL RESEARCH LETTERS 2014; 41:4456-4462. [PMID: 25821267 PMCID: PMC4373172 DOI: 10.1002/grl.51829] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/11/2014] [Indexed: 05/09/2023]
Abstract
UNLABELLED Evidence for deliquescence of perchlorate salts has been discovered in the Martian polar region while possible brine flows have been observed in the equatorial region. This appears to contradict the idea that bulk deliquescence is too slow to occur during the short periods of the Martian diurnal cycle during which conditions are favorable for it. We conduct laboratory experiments to study the formation of liquid brines at Mars environmental conditions. We find that when water vapor is the only source of water, bulk deliquescence of perchlorates is not rapid enough to occur during the short periods of the day during which the temperature is above the salts' eutectic value, and the humidity is above the salts' deliquescence value. However, when the salts are in contact with water ice, liquid brine forms in minutes, indicating that aqueous solutions could form temporarily where salts and ice coexist on the Martian surface and in the shallow subsurface. KEY POINTS The formation of brines at Martian conditions was studied experimentallyBulk deliquescence from water vapor is too slow to occur diurnally on MarsBrines form in minutes when salts are placed in direct contact with ice.
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Affiliation(s)
- Erik Fischer
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Germán M Martínez
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Harvey M Elliott
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Nilton O Rennó
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
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54
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Fischer E, Martínez GM, Elliott HM, Rennó NO. Experimental evidence for the formation of liquid saline water on Mars. GEOPHYSICAL RESEARCH LETTERS 2014. [PMID: 25821267 DOI: 10.1002/2014gl060302] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
UNLABELLED Evidence for deliquescence of perchlorate salts has been discovered in the Martian polar region while possible brine flows have been observed in the equatorial region. This appears to contradict the idea that bulk deliquescence is too slow to occur during the short periods of the Martian diurnal cycle during which conditions are favorable for it. We conduct laboratory experiments to study the formation of liquid brines at Mars environmental conditions. We find that when water vapor is the only source of water, bulk deliquescence of perchlorates is not rapid enough to occur during the short periods of the day during which the temperature is above the salts' eutectic value, and the humidity is above the salts' deliquescence value. However, when the salts are in contact with water ice, liquid brine forms in minutes, indicating that aqueous solutions could form temporarily where salts and ice coexist on the Martian surface and in the shallow subsurface. KEY POINTS The formation of brines at Martian conditions was studied experimentallyBulk deliquescence from water vapor is too slow to occur diurnally on MarsBrines form in minutes when salts are placed in direct contact with ice.
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Affiliation(s)
- Erik Fischer
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Germán M Martínez
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Harvey M Elliott
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
| | - Nilton O Rennó
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
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Hawkings JR, Wadham JL, Tranter M, Raiswell R, Benning LG, Statham PJ, Tedstone A, Nienow P, Lee K, Telling J. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans. Nat Commun 2014; 5:3929. [PMID: 24845560 PMCID: PMC4050262 DOI: 10.1038/ncomms4929] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 04/22/2014] [Indexed: 11/22/2022] Open
Abstract
The Greenland and Antarctic Ice Sheets cover ~\n10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40–2.54 Tg per year in Greenland and 0.06–0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting. Glacial meltwaters may help fertilize the iron-limited Polar Oceans, yet the contribution is poorly constrained. Hawkings et al. monitor iron fluxes during a full-melt season in Greenland, and propose that ice sheets provide highly reactive and potentially bioavailable iron, comparable with aeolian dust fluxes.
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Affiliation(s)
- Jon R Hawkings
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Jemma L Wadham
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Martyn Tranter
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Rob Raiswell
- Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Liane G Benning
- Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Peter J Statham
- School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK
| | - Andrew Tedstone
- School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Peter Nienow
- School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Katherine Lee
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Jon Telling
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
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56
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Bakermans C, Skidmore ML, Douglas S, McKay CP. Molecular characterization of bacteria from permafrost of the Taylor Valley, Antarctica. FEMS Microbiol Ecol 2014; 89:331-46. [DOI: 10.1111/1574-6941.12310] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 02/18/2014] [Accepted: 02/19/2014] [Indexed: 12/01/2022] Open
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Raven JA. The evolution of autotrophy in relation to phosphorus requirement. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:4023-46. [PMID: 24123454 DOI: 10.1093/jxb/ert306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The evolution of autotrophy is considered in relation to the availability of phosphorus (P), the ultimate elemental resource limiting biological productivity through Earth's history. Work on microbes and plants is emphasized, dealing in turn with the main uses for P in cells, namely nucleic acids, phospholipids, and water-soluble low molecular mass phosphate esters plus metabolically active inorganic orthophosphate. There is a greater minimum gene number and minimum DNA content in autotrophic than in osmochemoorganotrophic archaea and bacteria, as well as a lower rate of biomass increase per unit P (P-use efficiency) in autotrophs than in osmochemoorganotrophs, in eukaryotes as well as bacteria. This may be due to the diversion of rRNA from producing proteins common to all organisms to producing highly expressed proteins specific to autotrophs. The P requirement for phospholipids is decreased in oxygenic photolithotrophs, and some anoxygenic photolithotrophs, by substituting galactolipids and sulpholipids for phospholipids in the photosynthetic, and some other, membranes. The six different autotrophic inorganic carbon assimilation pathways have varying requirements for low molecular mass water-soluble phosphate esters. In oxygenic photolithotrophs, there is no clear evidence of a different P requirement for growth in the absence (diffusive CO2 entry) relative to the presence of CO2-concentrating mechanisms (CCMs). P limitation increases the expression of crassulacean acid metabolism (CAM) in facultative CAM plants, decreases the extent of inorganic carbon accumulation in algae with CCMs, and (usually) their inorganic carbon affinity and the water-use efficiency of growth of terrestrial plants, and the light-use efficiency of photolithotrophs.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
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58
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Dold B, Gonzalez-Toril E, Aguilera A, Lopez-Pamo E, Cisternas ME, Bucchi F, Amils R. Acid rock drainage and rock weathering in Antarctica: important sources for iron cycling in the Southern Ocean. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:6129-36. [PMID: 23682976 DOI: 10.1021/es305141b] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Here we describe biogeochemical processes that lead to the generation of acid rock drainage (ARD) and rock weathering on the Antarctic landmass and describe why they are important sources of iron into the Antarctic Ocean. During three expeditions, 2009-2011, we examined three sites on the South Shetland Islands in Antarctica. Two of them displayed intensive sulfide mineralization and generated acidic (pH 3.2-4.5), iron-rich drainage waters (up to 1.78 mM Fe), which infiltrated as groundwater (as Fe(2+)) and as superficial runoff (as Fe(3+)) into the sea, the latter with the formation of schwertmannite in the sea-ice. The formation of ARD in the Antarctic was catalyzed by acid mine drainage microorganisms found in cold climates, including Acidithiobacillus ferrivorans and Thiobacillus plumbophilus. The dissolved iron (DFe) flux from rock weathering (nonmineralized control site) was calculated to be 0.45 × 10(9) g DFe yr(-1) for the nowadays 5468 km of ice-free Antarctic rock coastline which is of the same order of magnitude as glacial or aeolian input to the Southern Ocean. Additionally, the two ARD sites alone liberate 0.026 and 0.057 × 10(9) g DFe yr(-1) as point sources to the sea. The increased iron input correlates with increased phytoplankton production close to the source. This might even be enhanced in the future by a global warming scenario, and could be a process counterbalancing global warming.
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Affiliation(s)
- B Dold
- Instituto de Geología Económica Aplicada, Universidad de Concepción, Concepción, Chile
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Dachwald B, Ulamec S, Biele J. Clean In Situ Subsurface Exploration of Icy Environments in the Solar System. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/978-94-007-6546-7_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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60
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Raven JA. Iron acquisition and allocation in stramenopile algae. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:2119-27. [PMID: 23658428 DOI: 10.1093/jxb/ert121] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The essential element iron has a low biological availability in the surface ocean where photosynthetic organisms live. Recent advances in our understanding of iron acquisition mechanisms in brown algae and diatoms (stramenopile algae) show the importance of the reduction of ferric to ferrous iron prior to, or during, transport in the uptake process. The uses of iron in photosynthetic stramenopiles resembles that in other oxygenic organisms, although (with the exception of the diatom Thalassiosira oceanica from an iron-deficient part of the ocean) they lack plastocyanin, instead using cytochrome c 6, This same diatom further economizes genotypically on the use of iron in photosynthesis by decreasing the expression of photosystem I, cytochrome c 6, and the cytochrome b 6 f complex per cell and per photosystem II relative to the coastal Thalassiosira pseudonana; similar changes occur phenotypically in response to iron deficiency in other diatoms such as Phaeodactylum tricornutum. In some diatoms grown under iron-limiting conditions, essentially all of the iron in the cells can be accounted for by the iron occurring in catalytic proteins. However, stramenopiles can store iron. Genomic studies show that pennate, but not centric, diatoms have the iron storage protein ferritin. While Mössbauer and X-ray analysis of (57)Fe-labelled Ectocarpus siliculosus shows iron in an amorphous mineral phase resembling the core of ferritin, the genome shows no protein with significant sequence similarity to ferritin.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
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61
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Wilkins D, Yau S, Williams TJ, Allen MA, Brown MV, DeMaere MZ, Lauro FM, Cavicchioli R. Key microbial drivers in Antarctic aquatic environments. FEMS Microbiol Rev 2013; 37:303-35. [DOI: 10.1111/1574-6976.12007] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 08/11/2012] [Accepted: 10/01/2012] [Indexed: 11/27/2022] Open
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62
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Goordial J, Lamarche-Gagnon G, Lay CY, Whyte L. Left Out in the Cold: Life in Cryoenvironments. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/978-94-007-6488-0_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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63
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Dassarma S, Capes MD, Karan R, Dassarma P. Amino acid substitutions in cold-adapted proteins from Halorubrum lacusprofundi, an extremely halophilic microbe from antarctica. PLoS One 2013; 8:e58587. [PMID: 23536799 PMCID: PMC3594186 DOI: 10.1371/journal.pone.0058587] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/05/2013] [Indexed: 11/18/2022] Open
Abstract
The halophilic Archaeon Halorubrum lacusprofundi, isolated from the perennially cold and hypersaline Deep Lake in Antarctica, was recently sequenced and compared to 12 Haloarchaea from temperate climates by comparative genomics. Amino acid substitutions for 604 H. lacusprofundi proteins belonging to conserved haloarchaeal orthologous groups (cHOGs) were determined and found to occur at 7.85% of positions invariant in proteins from mesophilic Haloarchaea. The following substitutions were observed most frequently: (a) glutamic acid with aspartic acid or alanine; (b) small polar residues with other small polar or non-polar amino acids; (c) small non-polar residues with other small non-polar residues; (d) aromatic residues, especially tryptophan, with other aromatic residues; and (e) some larger polar residues with other similar residues. Amino acid substitutions for a cold-active H. lacusprofundi β-galactosidase were then examined in the context of a homology modeled structure at residues invariant in homologous enzymes from mesophilic Haloarchaea. Similar substitutions were observed as in the genome-wide approach, with the surface accessible regions of β-galactosidase displaying reduced acidity and increased hydrophobicity, and internal regions displaying mainly subtle changes among smaller non-polar and polar residues. These findings are consistent with H. lacusprofundi proteins displaying amino acid substitutions that increase structural flexibility and protein function at low temperature. We discuss the likely mechanisms of protein adaptation to a cold, hypersaline environment on Earth, with possible relevance to life elsewhere.
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Affiliation(s)
- Shiladitya Dassarma
- Department of Microbiology and Immunology, and Institute of Marine and Environmental Technology, University of Maryland, Baltimore, Maryland, United States of America.
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64
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Abstract
The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (-13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida's brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H(2)), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L(-1) nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans.
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65
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Carmichael JD, Pettit EC, Hoffman M, Fountain A, Hallet B. Seismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jf002221] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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66
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Kong W, Dolhi JM, Chiuchiolo A, Priscu J, Morgan-Kiss RM. Evidence of form II RubisCO (cbbM) in a perennially ice-covered Antarctic lake. FEMS Microbiol Ecol 2012; 82:491-500. [PMID: 22703237 DOI: 10.1111/j.1574-6941.2012.01431.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 06/10/2012] [Accepted: 06/11/2012] [Indexed: 11/27/2022] Open
Affiliation(s)
- Weidong Kong
- Department of Microbiology; Miami University; Oxford; OH; USA
| | - Jenna M. Dolhi
- Department of Microbiology; Miami University; Oxford; OH; USA
| | - Amy Chiuchiolo
- Department of Land Resources and Environmental Sciences; Montana State University; Bozeman; MT; USA
| | - John Priscu
- Department of Land Resources and Environmental Sciences; Montana State University; Bozeman; MT; USA
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67
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Dissolved gases in frozen basal water from the NGRIP borehole: implications for biogeochemical processes beneath the Greenland Ice Sheet. Polar Biol 2012. [DOI: 10.1007/s00300-012-1198-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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68
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Cameron KA, Hodson AJ, Osborn AM. Carbon and nitrogen biogeochemical cycling potentials of supraglacial cryoconite communities. Polar Biol 2012. [DOI: 10.1007/s00300-012-1178-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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69
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Diversity and expression of RubisCO genes in a perennially ice-covered Antarctic lake during the polar night transition. Appl Environ Microbiol 2012; 78:4358-66. [PMID: 22492447 DOI: 10.1128/aem.00029-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The autotrophic communities in the lakes of the McMurdo Dry Valleys, Antarctica, have generated interest since the early 1960s owing to low light transmission through the permanent ice covers, a strongly bimodal seasonal light cycle, constant cold water temperatures, and geographical isolation. Previous work has shown that autotrophic carbon fixation in these lakes provides an important source of organic matter to this polar desert. Lake Bonney has two lobes separated by a shallow sill and is one of several chemically stratified lakes in the dry valleys that support year-round biological activity. As part of an International Polar Year initiative, we monitored the diversity and abundance of major isoforms of RubisCO in Lake Bonney by using a combined sequencing and quantitative PCR approach during the transition from summer to polar winter. Form ID RubisCO genes related to a stramenopile, a haptophyte, and a cryptophyte were identified, while primers specific for form IA/B RubisCO detected a diverse autotrophic community of chlorophytes, cyanobacteria, and chemoautotrophic proteobacteria. Form ID RubisCO dominated phytoplankton communities in both lobes of the lake and closely matched depth profiles for photosynthesis and chlorophyll. Our results indicate a coupling between light availability, photosynthesis, and rbcL mRNA levels in deep phytoplankton populations. Regulatory control of rbcL in phytoplankton living in nutrient-deprived shallow depths does not appear to be solely light dependent. The distinct water chemistries of the east and west lobes have resulted in depth- and lobe-dependent variability in RubisCO diversity, which plays a role in transcriptional activity of the key gene responsible for carbon fixation.
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70
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Seckbach J, Chela-Flores J. Habitable Environments by Extremophiles on Earth, the Solar System, and Elsewhere. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/978-94-007-2941-4_43] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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71
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Hoffman PF, Macdonald FA, Halverson GP. Chapter 5 Chemical sediments associated with Neoproterozoic glaciation: iron formation, cap carbonate, barite and phosphorite. ACTA ACUST UNITED AC 2011. [DOI: 10.1144/m36.5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractOrthochemical sediments associated with Neoproterozoic glaciation have prominence beyond their volumetric proportions because of the insights they provide on the nature of glaciation and the records they hold of the environment in which they were precipitated. Synglacial Fe formations are mineralogically simple (haematite jaspilite), and their trace element spectra resemble modern seawater, with a weaker hydrothermal signature than Archaean–Palaeoproterozoic Fe formations. Lithofacies associations implicate subglacial meltwater plumes as the agents of Fe(II) oxidation, and temporal oscillations in the plume flux as the cause of alternating Fe- and Mn-oxide deposits. Most if not all Neoproterozoic examples belong to the older Cryogenian (Sturtian) glaciation. Older and younger Cryogenian (Marinoan) cap carbonates are distinct. Only the younger have well-developed transgressive cap dolostones, which were laid down during the rise in global mean sea level resulting from ice-sheet meltdown. Marinoan cap dolostones have a suite of unusual sedimentary structures, indicating abnormal palaeoenvironmental conditions during their deposition. Assuming the meltdown of ice-sheets was rapid, cap dolostones were deposited from surface waters dominated by buoyant glacial meltwater, within and beneath which microbial activity probably catalysed dolomite nucleation. Former aragonite seafloor cement (crystal fans) found in deeper water limestone above Marinoan cap dolostones indicates carbonate oversaturation at depth, implying extreme concentrations of dissolved inorganic carbon. Barite is associated with a number of Marinoan cap dolostones, either as digitate seafloor cement associated with Fe-dolomite at the top of the cap dolostone, or as early diagenetic void-filling cement associated with tepee or tepee-like breccias. Seafloor barite marks a redoxcline in the water column across which euxinic Ba-rich waters upwelled, causing simultaneous barite titration and Fe(III) reduction. Phosphatic stromatolites, shrub-like structures and coated grains are associated with a glacioisostatically induced exposure surface on a cap dolostone in the NE of the West African craton, but this appears to be a singular occurrence of phosphorite formed during a Neoproterozoic deglaciation.
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Affiliation(s)
- Paul F. Hoffman
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA, 02138, USA
- School of Earth and Ocean Sciences, University of Victoria, Box 1700, Victoria, BC V6W 2Y2, Canada
| | - Francis A. Macdonald
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA, 02138, USA
| | - Galen P. Halverson
- School of Earth and Environmental Sciences, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
- Present address: Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montréal, PQ H3A 2K6, Canada
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Spitzer J. From water and ions to crowded biomacromolecules: in vivo structuring of a prokaryotic cell. Microbiol Mol Biol Rev 2011; 75:491-506, second page of table of contents. [PMID: 21885682 PMCID: PMC3165543 DOI: 10.1128/mmbr.00010-11] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The interactions and processes which structure prokaryotic cytoplasm (water, ions, metabolites, and biomacromolecules) and ensure the fidelity of the cell cycle are reviewed from a physicochemical perspective. Recent spectroscopic and biological evidence shows that water has no active structuring role in the cytoplasm, an unnecessary notion still entertained in the literature; water acts only as a normal solvent and biochemical reactant. Subcellular structuring arises from localizations and interactions of biomacromolecules and from the growth and modifications of their surfaces by catalytic reactions. Biomacromolecular crowding is a fundamental physicochemical characteristic of cells in vivo. Though some biochemical and physiological effects of crowding (excluded volume effect) have been documented, crowding assays with polyglycols, dextrans, etc., do not properly mimic the compositional variety of biomacromolecules in vivo. In vitro crowding assays are now being designed with proteins, which better reflect biomacromolecular environments in vivo, allowing for hydrophobic bonding and screened electrostatic interactions. I elaborate further the concept of complex vectorial biochemistry, where crowded biomacromolecules structure the cytosol into electrolyte pathways and nanopools that electrochemically "wire" the cell. Noncovalent attractions between biomacromolecules transiently supercrowd biomacromolecules into vectorial, semiconducting multiplexes with a high (35 to 95%)-volume fraction of biomacromolecules; consequently, reservoirs of less crowded cytosol appear in order to maintain the experimental average crowding of ∼25% volume fraction. This nonuniform crowding model allows for fast diffusion of biomacromolecules in the uncrowded cytosolic reservoirs, while the supercrowded vectorial multiplexes conserve the remarkable repeatability of the cell cycle by preventing confusing cross talk of concurrent biochemical reactions.
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Affiliation(s)
- Jan Spitzer
- Mallard Creek Polymers, Inc., 14700 Mallard Creek Road, Charlotte, NC 28262, USA.
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Schulze-Makuch D, Haque S, de Sousa Antonio MR, Ali D, Hosein R, Song YC, Yang J, Zaikova E, Beckles DM, Guinan E, Lehto HJ, Hallam SJ. Microbial life in a liquid asphalt desert. ASTROBIOLOGY 2011; 11:241-258. [PMID: 21480792 DOI: 10.1089/ast.2010.0488] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Pitch Lake in Trinidad and Tobago is a natural asphalt reservoir nourished by pitch seepage, a form of petroleum that consists of mostly asphaltines, from the surrounding oil-rich region. During upward seepage, pitch mixes with mud and gases under high pressure, and the lighter portion evaporates or is volatilized, which produces a liquid asphalt residue characterized by low water activity, recalcitrant carbon substrates, and noxious chemical compounds. An active microbial community of archaea and bacteria, many of them novel strains (particularly from the new Tar ARC groups), totaling a biomass of up to 10(7) cells per gram, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical and molecular taxonomic approaches revealed diverse, novel, and deeply branching microbial lineages with the potential to mediate anaerobic hydrocarbon degradation processes in different parts of the asphalt column. In addition, we found markers for archaeal methane metabolism and specific gene sequences affiliated with facultative and obligate anaerobic sulfur- and nitrite-oxidizing bacteria. The microbial diversity at Pitch Lake was found to be unique when compared to microbial communities analyzed at other hydrocarbon-rich environments, which included Rancho Le Brea, a natural asphalt environment in California, USA, and an oil well and a mud volcano in Trinidad and Tobago, among other sites. These results open a window into the microbial ecology and biogeochemistry of recalcitrant hydrocarbon matrices and establish the site as a terrestrial analogue for modeling the biotic potential of hydrocarbon lakes such as those found on Saturn's largest moon Titan.
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Affiliation(s)
- Dirk Schulze-Makuch
- School of Earth and Environmental Sciences, Washington State University, Pullman, 99164-6376, USA.
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Abstract
Airborne radar surveys performed over East Antarctica reveal massive and widespread bodies of accreted basal ice.
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Affiliation(s)
- Slawek Tulaczyk
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA.
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Foreman CM, Dieser M, Greenwood M, Cory RM, Laybourn-Parry J, Lisle JT, Jaros C, Miller PL, Chin YP, McKnight DM. When a habitat freezes solid: microorganisms over-winter within the ice column of a coastal Antarctic lake. FEMS Microbiol Ecol 2011; 76:401-12. [DOI: 10.1111/j.1574-6941.2011.01061.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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76
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Skidmore M. Microbial communities in Antarctic subglacial aquatic environments. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010gm000995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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77
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Gostinčar C, Lenassi M, Gunde-Cimerman N, Plemenitaš A. Fungal adaptation to extremely high salt concentrations. ADVANCES IN APPLIED MICROBIOLOGY 2011; 77:71-96. [PMID: 22050822 DOI: 10.1016/b978-0-12-387044-5.00003-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hypersaline environments support substantial microbial communities of selected halotolerant and halophilic organisms, including fungi from various orders. In hypersaline water of solar salterns, the black yeast Hortaea werneckii is by far the most successful fungal representative. It has an outstanding ability to overcome the turgor loss and sodium toxicity that are typical for hypersaline environments, which facilitates its growth even in solutions that are almost saturated with NaCl. We propose a model of cellular responses to high salt concentrations that integrates the current knowledge of H. werneckii adaptations. The negative impact of a hyperosmolar environment is counteracted by an increase in the energy supply that is needed to drive the energy-demanding export of ions and synthesis of compatible solutes. Changes in membrane lipid composition and cell-wall structure maintain the integrity and functioning of the stressed cells. Understanding the salt responses of H. werneckii and other fungi (e.g., the halophilic Wallemia ichthyophaga) will extend our knowledge of fungal stress tolerance and promote the use of the currently unexploited biotechnological potential of fungi that live in hypersaline environments.
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78
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Siple Coast subglacial aquatic environments: The Whillans Ice Stream Subglacial Access Research Drilling Project. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010gm000932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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79
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Onstott TC, McGown DJ, Bakermans C, Ruskeeniemi T, Ahonen L, Telling J, Soffientino B, Pfiffner SM, Sherwood-Lollar B, Frape S, Stotler R, Johnson EJ, Vishnivetskaya TA, Rothmel R, Pratt LM. Microbial communities in subpermafrost saline fracture water at the Lupin Au mine, Nunavut, Canada. MICROBIAL ECOLOGY 2009; 58:786-807. [PMID: 19568805 DOI: 10.1007/s00248-009-9553-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2009] [Accepted: 06/06/2009] [Indexed: 05/22/2023]
Abstract
We report the first investigation of a deep subpermafrost microbial ecosystem, a terrestrial analog for the Martian subsurface. Our multidisciplinary team analyzed fracture water collected at 890 and 1,130 m depths beneath a 540-m-thick permafrost layer at the Lupin Au mine (Nunavut, Canada). 14C, 3H, and noble gas isotope analyses suggest that the Na-Ca-Cl, suboxic, fracture water represents a mixture of geologically ancient brine, approximately25-kyr-old, meteoric water and a minor modern talik-water component. Microbial planktonic concentrations were approximately10(3) cells mL(-1). Analysis of the 16S rRNA gene from extracted DNA and enrichment cultures revealed 42 unique operational taxonomic units in 11 genera with Desulfosporosinus, Halothiobacillus, and Pseudomonas representing the most prominent phylotypes and failed to detect Archaea. The abundance of terminally branched and midchain-branched saturated fatty acids (5 to 15 mol%) was consistent with the abundance of Gram-positive bacteria in the clone libraries. Geochemical data, the ubiquinone (UQ) abundance (3 to 11 mol%), and the presence of both aerobic and anaerobic bacteria indicated that the environment was suboxic, not anoxic. Stable sulfur isotope analyses of the fracture water detected the presence of microbial sulfate reduction, and analyses of the vein-filling pyrite indicated that it was in isotopic equilibrium with the dissolved sulfide. Free energy calculations revealed that sulfate reduction and sulfide oxidation via denitrification and not methanogenesis were the most thermodynamically viable consistent with the principal metabolisms inferred from the 16S rRNA community composition and with CH4 isotopic compositions. The sulfate-reducing bacteria most likely colonized the subsurface during the Pleistocene or earlier, whereas aerobic bacteria may have entered the fracture water networks either during deglaciation prior to permafrost formation 9,000 years ago or from the nearby talik through the hydrologic gradient created during mine dewatering. Although the absence of methanogens from this subsurface ecosystem is somewhat surprising, it may be attributable to an energy bottleneck that restricts their migration from surface permafrost deposits where they are frequently reported. These results have implications for the biological origin of CH4 on Mars.
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Affiliation(s)
- T C Onstott
- Department of Geosciences, Princeton University, Princeton, 08544, NJ 08544, USA.
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Bioprospecting for microbial products that affect ice crystal formation and growth. Appl Microbiol Biotechnol 2009; 85:481-9. [DOI: 10.1007/s00253-009-2291-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 10/01/2009] [Accepted: 10/03/2009] [Indexed: 10/20/2022]
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Affiliation(s)
- Antje Boetius
- HGF-MPG Joint Research Group for Deep Sea Ecology and Technology, Alfred Wegener Institute for Polar and Marine Research, 27515 Bremerhaven, Germany, and Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Samantha Joye
- Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
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Affiliation(s)
- Johanna Laybourn-Parry
- Institute of Antarctic and Southern Ocean Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
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83
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Life thrives beneath Antarctic glacier. Nature 2009. [DOI: 10.1038/news.2009.368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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