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[PMID]:28459604
[Au] Autor:Mickol RL; Page JL; Schuerger AC
[Ad] Endereço:1 Center for Space and Planetary Sciences, University of Arkansas , Fayetteville, Arkansas.
[Ti] Título:Magnesium Sulfate Salt Solutions and Ices Fail to Protect Serratia liquefaciens from the Biocidal Effects of UV Irradiation under Martian Conditions.
[So] Source:Astrobiology;17(5):401-412, 2017 May.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The growth of Serratia liquefaciens has been demonstrated under martian conditions of 0.7 kPa (7 mbar), 0°C, and CO -enriched anoxic atmospheres (Schuerger et al., 2013, Astrobiology 13:115-131), but studies into the survivability of cells under hypersaline conditions that are likely to be encountered on Mars are lacking. Serratia liquefaciens cells were suspended in aqueous MgSO solutions, or frozen brines, and exposed to terrestrial (i.e., 101.3 kPa, 24°C, O /N -normal atmosphere) or martian (i.e., 0.7 kPa, -25°C, CO -anoxic atmosphere) conditions to assess the roles of MgSO and UV irradiation on the survival of S. liquefaciens. Four solutions were tested for their capability to attenuate martian UV irradiation in both liquid and frozen forms: sterile deionized water (SDIW), 10 mM PO buffer, 5% MgSO , and 10% MgSO . None of the solutions in either liquid or frozen forms provided enhanced protection against martian UV irradiation. Sixty minutes of UV irradiation reduced cell densities from 2.0 × 10 cells/mL to less than 10 cells/mL for both liquid and frozen solutions. In contrast, 3-4 mm of a Mars analog soil were sufficient to attenuate 100% of UV irradiation. Results suggest that terrestrial microorganisms may not survive on Sun-exposed surfaces on Mars, even if the cells are embedded in frozen martian brines composed of MgSO . However, if dispersed microorganisms can be covered by only a few millimeters of dust or regolith, long-term survival is probable. Key Words: Hypobaria-Mars-Planetary protection-Brines. Astrobiology 17, 401-412.
[Mh] Termos MeSH primário: Serratia liquefaciens/efeitos da radiação
Raios Ultravioleta
[Mh] Termos MeSH secundário: Exobiologia
Meio Ambiente Extraterreno
Gelo
Sulfato de Magnésio
Serratia liquefaciens/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Ice); 7487-88-9 (Magnesium Sulfate)
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171214
[Lr] Data última revisão:
171214
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170502
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2015.1448


  2 / 1681 MEDLINE  
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[PMID]:28470425
[Au] Autor:Ranawat P; Rawat S
[Ad] Endereço:Department of Botany and Microbiology, Hemvati Nandan Bahuguna Garhwal University, Srinagar (Garhwal), Uttrakhand, India.
[Ti] Título:Radiation resistance in thermophiles: mechanisms and applications.
[So] Source:World J Microbiol Biotechnol;33(6):112, 2017 Jun.
[Is] ISSN:1573-0972
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:The study of prokaryotic life in high temperature environments viz., geothermal areas, hot, acidic geysers and undersea hydrothermal vents has revealed the existence of thermophiles (or hyperthermophiles). These microorganisms possess various stress adaptation mechanisms which enable them to bypass multiple physical and chemical barriers for survival. The discovery of radiation resistant thermophile Deinococcus geothermalis has given new insights into the field of radiation microbiology. The ability of radiation resistant thermophiles to deal with the lethal effects of ionizing radiations like DNA damage, oxidative bursts and protein damage has made them a model system for exobiology and interplanetary transmission of life. They might be an antiquity of historical transport process that brought microbial life on Earth. These radiation resistant thermophiles are resistant to desiccation as well and maintain their homeostasis by advance DNA repair mechanisms, reactive oxygen species (ROS) detoxification system and accumulation of compatible solutes. Moreover, engineered radioresistant thermophilic strains are the best candidate for bioremediation of radionuclide waste while the extremolytes produced by these organisms may have predicted therapeutic uses. So, the present article delineate a picture of radiation resistance thermophiles, their adaptive mechanisms to evade stress viz., radiation and desiccation, their present applications along with new horizons in near future.
[Mh] Termos MeSH primário: Archaea/fisiologia
Archaea/efeitos da radiação
Bactérias/efeitos da radiação
Fenômenos Fisiológicos Bacterianos/efeitos da radiação
Temperatura Alta
[Mh] Termos MeSH secundário: Actinobacteria/fisiologia
Actinobacteria/efeitos da radiação
Bactérias/genética
Fenômenos Fisiológicos Bacterianos/genética
Biodegradação Ambiental
Cianobactérias/fisiologia
Cianobactérias/efeitos da radiação
Dano ao DNA/efeitos da radiação
Reparo do DNA
Deinococcus/genética
Deinococcus/fisiologia
Deinococcus/efeitos da radiação
Microbiologia Ambiental
Exobiologia
Halobacterium/fisiologia
Halobacterium/efeitos da radiação
Pyrococcus/fisiologia
Pyrococcus/efeitos da radiação
Radiação Ionizante
Espécies Reativas de Oxigênio/efeitos da radiação
Explosão Respiratória/efeitos da radiação
Estresse Fisiológico
Sulfolobus/fisiologia
Sulfolobus/efeitos da radiação
Thermococcus/fisiologia
Thermococcus/efeitos da radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Reactive Oxygen Species)
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171201
[Lr] Data última revisão:
171201
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170505
[St] Status:MEDLINE
[do] DOI:10.1007/s11274-017-2279-5


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[PMID]:28541174
[Au] Autor:Cirkovic MM
[Ti] Título:Enhancing a Person, Enhancing a Civilization: A Research Program at the Intersection of Bioethics, Future Studies, and Astrobiology.
[So] Source:Camb Q Healthc Ethics;26(3):459-468, 2017 Jul.
[Is] ISSN:1469-2147
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:There are manifold intriguing issues located within largely unexplored borderlands of bioethics, future studies (including global risk analysis), and astrobiology. Human enhancement has for quite some time been among the foci of bioethical debates, but the same cannot be said about its global, transgenerational, and even cosmological consequences. In recent years, discussions of posthuman and, in general terms, postbiological civilization(s) have slowly gained a measure of academic respect, in parallel with the renewed interest in the entire field of future studies and the great strides made in understanding of the origin and evolution of life and intelligence in their widest, cosmic context. These developments promise much deeper synergic answers to questions regarding the long-term future of enhancement: how far can it go? Is human enhancement a further step toward building a true postbiological civilization? Should we actively participate and help shape this process? Is the future of humanity "typical" in the same Copernican sense as our location in space and time is typical in the galaxy, and if so, can we derive important insights about the evolutionary pathways of postbiological evolution from astrobiological and Search for ExtraTerrestrial Intelligence (SETI) studies? These and similar questions could be understood as parts of a possible unifying research program attempting to connect cultural and moral evolution with what we know and understand about their cosmological and biological counterparts.
[Mh] Termos MeSH primário: Melhoramento Biomédico/ética
Civilização
Exobiologia
Meio Ambiente Extraterreno
Inteligência
[Mh] Termos MeSH secundário: Temas Bioéticos
Previsões
Seres Humanos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171113
[Lr] Data última revisão:
171113
[Sb] Subgrupo de revista:E; IM
[Da] Data de entrada para processamento:170526
[St] Status:MEDLINE
[do] DOI:10.1017/S0963180116001134


  4 / 1681 MEDLINE  
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[PMID]:28426003
[Au] Autor:Dittmann JA; Irwin JM; Charbonneau D; Bonfils X; Astudillo-Defru N; Haywood RD; Berta-Thompson ZK; Newton ER; Rodriguez JE; Winters JG; Tan TG; Almenara JM; Bouchy F; Delfosse X; Forveille T; Lovis C; Murgas F; Pepe F; Santos NC; Udry S; Wünsche A; Esquerdo GA; Latham DW; Dressing CD
[Ad] Endereço:Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
[Ti] Título:A temperate rocky super-Earth transiting a nearby cool star.
[So] Source:Nature;544(7650):333-336, 2017 04 19.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars. Statistical results suggest that the nearest transiting Earth-sized planet in the liquid-water, habitable zone of an M dwarf star is probably around 10.5 parsecs away. A temperate planet has been discovered orbiting Proxima Centauri, the closest M dwarf, but it probably does not transit and its true mass is unknown. Seven Earth-sized planets transit the very low-mass star TRAPPIST-1, which is 12 parsecs away, but their masses and, particularly, their densities are poorly constrained. Here we report observations of LHS 1140b, a planet with a radius of 1.4 Earth radii transiting a small, cool star (LHS 1140) 12 parsecs away. We measure the mass of the planet to be 6.6 times that of Earth, consistent with a rocky bulk composition. LHS 1140b receives an insolation of 0.46 times that of Earth, placing it within the liquid-water, habitable zone. With 90 per cent confidence, we place an upper limit on the orbital eccentricity of 0.29. The circular orbit is unlikely to be the result of tides and therefore was probably present at formation. Given its large surface gravity and cool insolation, the planet may have retained its atmosphere despite the greater luminosity (compared to the present-day) of its host star in its youth. Because LHS 1140 is nearby, telescopes currently under construction might be able to search for specific atmospheric gases in the future.
[Mh] Termos MeSH primário: Meio Ambiente Extraterreno/química
Planetas
Astros Celestes
Temperatura Ambiente
[Mh] Termos MeSH secundário: Exobiologia
Água/análise
Água/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
059QF0KO0R (Water)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170824
[Lr] Data última revisão:
170824
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170421
[St] Status:MEDLINE
[do] DOI:10.1038/nature22055


  5 / 1681 MEDLINE  
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[PMID]:28418707
[Au] Autor:Cockell CS; Brown S; Landenmark H; Samuels T; Siddall R; Wadsworth J
[Ad] Endereço:UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK.
[Ti] Título:Liquid Water Restricts Habitability in Extreme Deserts.
[So] Source:Astrobiology;17(4):309-318, 2017 Apr.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water. Key Words: Deserts-Extremophiles-Stress-High temperatures-UV radiation-Desiccation. Astrobiology 17, 309-318.
[Mh] Termos MeSH primário: Clima Desértico
Exobiologia
Meio Ambiente Extraterreno
Água
[Mh] Termos MeSH secundário: Cianobactérias/citologia
Cianobactérias/efeitos da radiação
Dessecação
Esterases/metabolismo
Congelamento
Viabilidade Microbiana/efeitos da radiação
Temperatura Ambiente
Raios Ultravioleta
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
059QF0KO0R (Water); EC 3.1.- (Esterases)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170508
[Lr] Data última revisão:
170508
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170419
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2016.1580


  6 / 1681 MEDLINE  
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[PMID]:28418704
[Au] Autor:Reinhard CT; Olson SL; Schwieterman EW; Lyons TW
[Ad] Endereço:1 NASA Astrobiology Institute .
[Ti] Título:False Negatives for Remote Life Detection on Ocean-Bearing Planets: Lessons from the Early Earth.
[So] Source:Astrobiology;17(4):287-297, 2017 Apr.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes throughout its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has centered on refining our understanding of false positives for remote life detection, much less attention has been paid to the possibility of false negatives, that is, cryptic biospheres that are widespread and active on a planet's surface but are ultimately undetectable or difficult to detect in the composition of a planet's atmosphere. Here, we summarize recent developments from geochemical proxy records and Earth system models that provide insight into the long-term evolution of the most readily detectable potential biosignature gases on Earth-oxygen (O ), ozone (O ), and methane (CH ). We suggest that the canonical O -CH disequilibrium biosignature would perhaps have been challenging to detect remotely during Earth's ∼4.5-billion-year history and that in general atmospheric O /O levels have been a poor proxy for the presence of Earth's biosphere for all but the last ∼500 million years. We further suggest that detecting atmospheric CH would have been problematic for most of the last ∼2.5 billion years of Earth's history. More broadly, we stress that internal oceanic recycling of biosignature gases will often render surface biospheres on ocean-bearing silicate worlds cryptic, with the implication that the planets most conducive to the development and maintenance of a pervasive biosphere will often be challenging to characterize via conventional atmospheric biosignatures. Key Words: Biosignatures-Oxygen-Methane-Ozone-Exoplanets-Planetary habitability. Astrobiology 17, 287-297.
[Mh] Termos MeSH primário: Terra (Planeta)
Exobiologia
Meio Ambiente Extraterreno
Oceanos e Mares
Planetas
[Mh] Termos MeSH secundário: Atmosfera/química
Metano/análise
Oxigênio/análise
Ozônio/análise
Análise Espectral
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
66H7ZZK23N (Ozone); OP0UW79H66 (Methane); S88TT14065 (Oxygen)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170508
[Lr] Data última revisão:
170508
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170419
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2016.1598


  7 / 1681 MEDLINE  
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[PMID]:28282216
[Au] Autor:Poch O; Frey J; Roditi I; Pommerol A; Jost B; Thomas N
[Ad] Endereço:1 Center for Space and Habitability , Universität Bern, Bern, Switzerland .
[Ti] Título:Remote Sensing of Potential Biosignatures from Rocky, Liquid, or Icy (Exo)Planetary Surfaces.
[So] Source:Astrobiology;17(3):231-252, 2017 Mar.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:To detect signs of life by remote sensing on objects of our Solar System and on exoplanets, the characterization of light scattered by surface life material could complement possible clues given by the atmospheric composition. We reviewed the reflectance spectra of a broad selection of major biomolecules that constitute terrestrial carbon-based life from 0.4 to 2.4 µm, and we discuss their detectability through atmospheric spectral windows. Biomolecule features in the near-infrared (0.8-2.4 µm) will likely be obscured by water spectral features and some atmospheric gases. The visible range (0.4-0.8 µm), including the strong spectral features of pigments, is the most favorable. We investigated the detectability of a pigmented microorganism (Deinococcus radiodurans) when mixed with silica sand, liquid water, and water-ice particles representative of diverse surfaces of potentially habitable worlds. We measured the visible to near-infrared reflectance spectra (0.4-2.4 µm) and the visible phase curves (at 0.45 and 0.75 µm) of the mixtures to assess how the surface medium and the viewing geometry affect the detectability of the microorganisms. The results show that ice appears to be the most favorable medium for the detection of pigments. Water ice is bright and featureless from 0.4 to 0.8 µm, allowing the absorption of any pigment present in the ice to be well noticeable. We found that the visible phase curve of water ice is the most strongly affected by the presence of pigments, with variations of the spectral slope by more than a factor of 3 with phase angles. Finally, we show that the sublimation of the ice results in the concentration of the biological material onto the surface and the consequent increase of its signal. These results have applications to the search for life on icy worlds, such as Europa or Enceladus. Key Words: Remote sensing-Biosignatures-Reflectance spectroscopy-Exoplanets-Spectroscopic biosignatures-Pigments. Astrobiology 17, 231-252.
[Mh] Termos MeSH primário: Bactérias/metabolismo
Exobiologia/métodos
Meio Ambiente Extraterreno
Planetas
Tecnologia de Sensoriamento Remoto/métodos
[Mh] Termos MeSH secundário: Atmosfera/química
Deinococcus/metabolismo
Gelo
Origem da Vida
Dióxido de Silício/química
Água/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Ice); 059QF0KO0R (Water); 7631-86-9 (Silicon Dioxide)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171009
[Lr] Data última revisão:
171009
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170311
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2016.1523


  8 / 1681 MEDLINE  
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[PMID]:28230125
[Au] Autor:Gillon M; Triaud AH; Demory BO; Jehin E; Agol E; Deck KM; Lederer SM; de Wit J; Burdanov A; Ingalls JG; Bolmont E; Leconte J; Raymond SN; Selsis F; Turbet M; Barkaoui K; Burgasser A; Burleigh MR; Carey SJ; Chaushev A; Copperwheat CM; Delrez L; Fernandes CS; Holdsworth DL; Kotze EJ; Van Grootel V; Almleaky Y; Benkhaldoun Z; Magain P; Queloz D
[Ad] Endereço:Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
[Ti] Título:Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1.
[So] Source:Nature;542(7642):456-460, 2017 02 22.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away. The transiting configuration of these planets, combined with the Jupiter-like size of their host star-named TRAPPIST-1-makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities. Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.
[Mh] Termos MeSH primário: Planetas
Astros Celestes
[Mh] Termos MeSH secundário: Exobiologia
Meio Ambiente Extraterreno/química
Temperatura Ambiente
Água/análise
Água/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
059QF0KO0R (Water)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:171010
[Lr] Data última revisão:
171010
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170224
[St] Status:MEDLINE
[do] DOI:10.1038/nature21360


  9 / 1681 MEDLINE  
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[PMID]:28206823
[Au] Autor:Meeßen J; Backhaus T; Brandt A; Raguse M; Böttger U; de Vera JP; de la Torre R
[Ad] Endereço:1 Institute of Botany, Heinrich-Heine-University (HHU) , Düsseldorf, Germany .
[Ti] Título:The Effect of High-Dose Ionizing Radiation on the Isolated Photobiont of the Astrobiological Model Lichen Circinaria gyrosa.
[So] Source:Astrobiology;17(2):154-162, 2017 Feb.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Lichen symbioses between fungi and algae represent successful life strategies to colonize the most extreme terrestrial habitats. Consequently, space exposure and simulation experiments have demonstrated lichens' high capacity for survival, and thus, they have become models in astrobiological research with which to discern the limits and limitations of terrestrial life. In a series of ground-based irradiation experiments, the STARLIFE campaign investigated the resistance of astrobiological model organisms to galactic cosmic radiation, which is one of the lethal stressors of extraterrestrial environments. Since previous studies have identified that the alga is the more sensitive lichen symbiont, we chose the isolated photobiont Trebouxia sp. of the astrobiological model Circinaria gyrosa as a subject in the campaign. Therein, γ radiation was used to exemplify the deleterious effects of low linear energy transfer (LET) ionizing radiation at extremely high doses up to 113 kGy in the context of astrobiology. The effects were analyzed by chlorophyll a fluorescence of photosystem II (PSII), cultivation assays, live/dead staining and confocal laser scanning microscopy (CLSM), and Raman laser spectroscopy (RLS). The results demonstrate dose-dependent impairment of photosynthesis, the cessation of cell proliferation, cellular damage, a decrease in metabolic activity, and degradation of photosynthetic pigments. While previous investigations on other extraterrestrial stressors have demonstrated a high potential of resistance, results of this study reveal the limits of photobiont resistance to ionizing radiation and characterize γ radiation-induced damages. This study also supports parallel STARLIFE studies on the lichens Circinaria gyrosa and Xanthoria elegans, both of which harbor a Trebouxia sp. photobiont. Key Words: Astrobiology-Gamma rays-Extremotolerance-Ionizing radiation-Lichens-Photobiont. Astrobiology 17, 154-162.
[Mh] Termos MeSH primário: Exobiologia
Líquens/efeitos da radiação
Modelos Biológicos
Radiação Ionizante
[Mh] Termos MeSH secundário: Clorofila/análise
Relação Dose-Resposta à Radiação
Fluorescência
Lasers
Líquens/crescimento & desenvolvimento
Líquens/metabolismo
Fotossíntese/efeitos da radiação
Análise Espectral Raman
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
1406-65-1 (Chlorophyll); YF5Q9EJC8Y (chlorophyll a)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171009
[Lr] Data última revisão:
171009
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170217
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2015.1453


  10 / 1681 MEDLINE  
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[PMID]:28206822
[Au] Autor:de la Torre R; Miller AZ; Cubero B; Martín-Cerezo ML; Raguse M; Meeßen J
[Ad] Endereço:1 Departamento de Observación de la Tierra, Instituto Nacional de Técnica Aeroespacial (INTA) , Madrid, Spain .
[Ti] Título:The Effect of High-Dose Ionizing Radiation on the Astrobiological Model Lichen Circinaria gyrosa.
[So] Source:Astrobiology;17(2):145-153, 2017 Feb.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The lichen Circinaria gyrosa is an astrobiological model defined by its high capacity of resistance to space conditions and to a simulated martian environment. Therefore, it became part of the currently operated BIOMEX experiment on board the International Space Station and the recent STARLIFE campaign to study the effects of four types of space-relevant ionizing radiation. The samples were irradiated with helium and iron ions at doses up to 2 kGy, with X-rays at doses up to 5 kGy and with γ rays at doses from 6 to 113 kGy. Results on C. gyrosa's resistance to simulated space ionizing radiation and its post-irradiation viability were obtained by (i) chlorophyll a fluorescence of photosystem II (PSII), (ii) epifluorescence microscopy, (iii) confocal laser scanning microscopy (CLSM), and (iv) field emission scanning electron microscopy (FESEM). Results of photosynthetic activity and epifluorescence show no significant changes up to a dose of 1 kGy (helium ions), 2 kGy (iron ions), 5 kGy (X-rays)-the maximum doses applied for those radiation qualities-as well as a dose of 6 kGy of γ irradiation, which was the lowest dose applied for this low linear energy transfer (LET) radiation. Significant damage in a dose-related manner was observed only at much higher doses of γ irradiation (up to 113 kGy). These data corroborate the findings of the parallel STARLIFE studies on the effects of ionizing radiation on the lichen Circinaria gyrosa, its isolated photobiont, and the lichen Xanthoria elegans. Key Words: Simulated space ionizing radiation-Gamma rays-Extremotolerance-Lichens-Circinaria gyrosa-Photosynthetic activity. Astrobiology 17, 145-153.
[Mh] Termos MeSH primário: Exobiologia
Líquens/efeitos da radiação
Modelos Biológicos
Radiação Ionizante
[Mh] Termos MeSH secundário: Clorofila/análise
Relação Dose-Resposta à Radiação
Líquens/metabolismo
Líquens/ultraestrutura
Microscopia de Fluorescência
Fotossíntese/efeitos da radiação
Complexo de Proteína do Fotossistema II/metabolismo
Espectrometria por Raios X
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Photosystem II Protein Complex); 1406-65-1 (Chlorophyll); YF5Q9EJC8Y (chlorophyll a)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171009
[Lr] Data última revisão:
171009
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170217
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2015.1454



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