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Astrobiology

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https://www.readbyqxmd.com/read/28422534/in-situ-sampling-of-relative-dust-devil-particle-loads-and-their-vertical-grain-size-distributions
#1
Jan Raack, Dennis Reiss, Matthew R Balme, Kamal Taj-Eddine, Gian Gabriele Ori
During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (∼46...
April 19, 2017: Astrobiology
https://www.readbyqxmd.com/read/28151691/starlife-an-international-campaign-to-study-the-role-of-galactic-cosmic-radiation-in-astrobiological-model-systems
#2
Ralf Moeller, Marina Raguse, Stefan Leuko, Thomas Berger, Christine Elisabeth Hellweg, Akira Fujimori, Ryuichi Okayasu, Gerda Horneck
In-depth knowledge regarding the biological effects of the radiation field in space is required for assessing the radiation risks in space. To obtain this knowledge, a set of different astrobiological model systems has been studied within the STARLIFE radiation campaign during six irradiation campaigns (2013-2015). The STARLIFE group is an international consortium with the aim to investigate the responses of different astrobiological model systems to the different types of ionizing radiation (X-rays, γ rays, heavy ions) representing major parts of the galactic cosmic radiation spectrum...
February 2, 2017: Astrobiology
https://www.readbyqxmd.com/read/28151689/evaluation-of-the-resistance-of-chroococcidiopsis-spp-to-sparsely-and-densely-ionizing-irradiation
#3
Cyprien Verseux, Mickael Baqué, Riccardo Cifariello, Claudia Fagliarone, Marina Raguse, Ralf Moeller, Daniela Billi
Studying the resistance of cyanobacteria to ionizing radiation provides relevant information regarding astrobiology-related topics including the search for life on Mars, lithopanspermia, and biological life-support systems. Here, we report on the resistance of desert cyanobacteria of the genus Chroococcidiopsis, which were exposed (as part of the STARLIFE series of experiments) in both hydrated and dried states to ionizing radiation with different linear energy transfer values (0.2 to 200 keV/μm). Irradiation with up to 1 kGy of He or Si ions, 2 kGy of Fe ions, 5 kGy of X-rays, or 11...
February 2, 2017: Astrobiology
https://www.readbyqxmd.com/read/28418707/liquid-water-restricts-habitability-in-extreme-deserts
#4
Charles S Cockell, Sarah Brown, Hanna Landenmark, Toby Samuels, Rebecca Siddall, Jennifer Wadsworth
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...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28418706/radiation-driven-formation-of-reactive-oxygen-species-in-oxychlorine-containing-mars-surface-analogues
#5
Christos D Georgiou, Dimitrios Zisimopoulos, Electra Kalaitzopoulou, Richard C Quinn
The present study demonstrates that γ-radiolyzed perchlorate-containing Mars soil salt analogues (in a CO2 atmosphere) generate upon H2O wetting the reactive oxygen species (ROS) superoxide radical (O2(•-)), hydrogen peroxide (H2O2), and hydroxyl radicals ((•)OH). This study also validates that analogue radiolysis forms oxychlorine species that, in turn, can UV-photolyze to (•)OH upon UV photolysis. This investigation was made possible by the development of a new assay for inorganic-origin O2(•-) and H2O2 determination and by the modification of a previous assay for soil (•)OH...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28418705/accurate-differentiation-of-carotenoid-pigments-using-flight-representative-raman-spectrometers
#6
Cedric Malherbe, Ian B Hutchinson, Melissa McHugh, Richard Ingley, Jan Jehlička, Howell G M Edwards
Raman spectrometers will be utilized on two Mars rover missions, ExoMars and Mars 2020, in the near future, to search for evidence of life and habitable geological niches on Mars. Carotenoid pigments are recognized target biomarkers, and as they are highly active in Raman spectroscopy, they can be readily used to characterize the capabilities of space representative instrumentation. As part of the preparatory work being performed for the ExoMars mission, a gypsum crust colonized by microorganisms was interrogated with commercial portable Raman instruments and a flight representative Raman laser spectrometer...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28418704/false-negatives-for-remote-life-detection-on-ocean-bearing-planets-lessons-from-the-early-earth
#7
Christopher T Reinhard, Stephanie L Olson, Edward W Schwieterman, Timothy W Lyons
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...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28418703/radioresistance-of-adenine-to-cosmic-rays
#8
Gabriel S Vignoli Muniz, Christian F Mejía, Rafael Martinez, Basile Auge, Hermann Rothard, Alicja Domaracka, Philippe Boduch
The presence of nucleobases in carbonaceous meteorites on Earth is an indication of the existence of this class of molecules in outer space. However, space is permeated by ionizing radiation, which can have damaging effects on these molecules. Adenine is a purine nucleobase that amalgamates important biomolecules such as DNA, RNA, and ATP. Adenine has a unique importance in biochemistry and therefore life. The aim of this work was to study the effects of cosmic ray analogues on solid adenine and estimate its survival when exposed to corpuscular radiation...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28323456/stratosphere-conditions-inactivate-bacterial-endospores-from-a-mars-spacecraft-assembly-facility
#9
Christina L Khodadad, Gregory M Wong, Leandro M James, Prital J Thakrar, Michael A Lane, John A Catechis, David J Smith
Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 10(7) spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28177270/biosignature-preservation-and-detection-in-mars-analog-environments
#10
Lindsay E Hays, Heather V Graham, David J Des Marais, Elisabeth M Hausrath, Briony Horgan, Thomas M McCollom, M Niki Parenteau, Sally L Potter-McIntyre, Amy J Williams, Kennda L Lynch
This review of material relevant to the Conference on Biosignature Preservation and Detection in Mars Analog Environments summarizes the meeting materials and discussions and is further expanded upon by detailed references to the published literature. From this diverse source material, there is a detailed discussion on the habitability and biosignature preservation potential of five primary analog environments: hydrothermal spring systems, subaqueous environments, subaerial environments, subsurface environments, and iron-rich systems...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28323483/taphonomy-of-microbial-biosignatures-in-spring-deposits-a-comparison-of-modern-quaternary-and-jurassic-examples
#11
Sally L Potter-McIntyre, Jason Williams, Charity Phillips-Lander, Laura O'Connell
On Earth, microorganisms commonly enhance mineral precipitation and mediate mineralogical and chemical compositions of resulting deposits, particularly at spring systems. However, preservation of any type of microbial fossil or chemical or textural biosignature depends on the degree of alteration during diagenesis and factors such as exposure to diagenetic fluids. Little is known about the transformation of biosignatures during diagenesis over geologic time. Ten Mile Graben, Utah, USA, hosts a cold spring system that is an exceptional site for evaluation of diagenetic alteration of biosignatures because of the presence of modern springs with actively precipitating microbial mats and a series of progressively older tufa terraces (<400 ka) preserved in the area from the same spring system...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28323482/constraints-on-the-early-terrestrial-surface-uv-environment-relevant-to-prebiotic-chemistry
#12
Sukrit Ranjan, Dimitar D Sasselov
The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28323481/the-emergence-of-life-as-a-first-order-phase-transition
#13
Cole Mathis, Tanmoy Bhattacharya, Sara Imari Walker
It is well known that life on Earth alters its environment over evolutionary and geological timescales. An important open question is whether this is a result of evolutionary optimization or a universal feature of life. In the latter case, the origin of life would be coincident with a shift in environmental conditions. Here we present a model for the emergence of life in which replicators are explicitly coupled to their environment through the recycling of a finite supply of resources. The model exhibits a dynamic, first-order phase transition from nonlife to life, where the life phase is distinguished by selection on replicators...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28282220/identification-and-characterization-of-early-mission-phase-microorganisms-residing-on-the-mars-science-laboratory-and-assessment-of-their-potential-to-survive-mars-like-conditions
#14
Stephanie A Smith, James N Benardini, David Anderl, Matt Ford, Emmaleen Wear, Michael Schrader, Wayne Schubert, Linda DeVeaux, Andrzej Paszczynski, Susan E Childers
Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28282216/remote-sensing-of-potential-biosignatures-from-rocky-liquid-or-icy-exo-planetary-surfaces
#15
Olivier Poch, Joachim Frey, Isabel Roditi, Antoine Pommerol, Bernhard Jost, Nicolas Thomas
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...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28277783/origin-of-life-and-the-phosphate-transfer-catalyst
#16
Radosław W Piast, Rafał M Wieczorek
In this paper, we revisit several issues relevant to origin-of-life research and propose a Phosphate Transfer Catalyst hypothesis that furthers our understanding of some of the key events in prebiotic chemical evolution. In the Phosphate Transfer Catalyst hypothesis, we assume the existence of hypothetical metallopeptides with phosphate transfer activity that use abundant polyphosphates as both substrates and energy sources. Nonspecific catalysis by this phosphate transfer catalyst would provide a variety of different products such as phosphoryl amino acids, nucleosides, polyphosphate nucleotides, nucleic acids, and aminoacylated nucleic acids...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28263676/survival-and-dna-damage-in-plant-seeds-exposed-for-558-and-682-days-outside-the-international-space-station
#17
David Tepfer, Sydney Leach
For life to survive outside the biosphere, it must be protected from UV light and other radiation by exterior shielding or through sufficient inherent resistance to survive without protection. We tested the plausibility of inherent resistance in plant seeds, reporting in a previous paper that Arabidopsis thaliana and tobacco (Nicotiana tabacum) seeds exposed for 558 days outside the International Space Station (ISS) germinated and developed into fertile plants after return to Earth. We have now measured structural genetic damage in tobacco seeds from this EXPOSE-E experiment by quantitatively amplifying a segment of an antibiotic resistance gene, nptII, inserted into the chloroplast genome...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28206823/the-effect-of-high-dose-ionizing-radiation-on-the-isolated-photobiont-of-the-astrobiological-model-lichen-circinaria-gyrosa
#18
Joachim Meeßen, Theresa Backhaus, Annette Brandt, Marina Raguse, Ute Böttger, Jean-Pierre de Vera, Rosa de la Torre
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...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206822/the-effect-of-high-dose-ionizing-radiation-on-the-astrobiological-model-lichen-circinaria-gyrosa
#19
Rosa de la Torre, Ana Zélia Miller, Beatriz Cubero, M Luisa Martín-Cerezo, Marina Raguse, Joachim Meeßen
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...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206821/simulated-space-radiation-impact-of-four-different-types-of-high-dose-ionizing-radiation-on-the-lichen-xanthoria-elegans
#20
Annette Brandt, Joachim Meeßen, Reiner U Jänicke, Marina Raguse, Sieglinde Ott
This study addresses the viability of the lichen Xanthoria elegans after high-dose ionizing irradiation in the frame of the STARLIFE campaign. The first set of experiments was intended to resemble several types of galactic cosmic radiation (GCR) as present beyond the magnetic shield of Earth. In the second set of experiments, γ radiation up to 113 kGy was applied to test the limit of lichen resistance to ionizing radiation. Entire thalli of Xanthoria elegans were irradiated in the anhydrobiotic state. After STARLIFE 1, the metabolic activity of both symbionts was quantified by live/dead staining with confocal laser scanning microscopy...
February 2017: Astrobiology
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