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https://www.readbyqxmd.com/read/28537771/atmospheric-constraints-on-the-surface-uv-environment-of-mars-at-3-9%C3%A2-ga-relevant-to-prebiotic-chemistry
#1
Sukrit Ranjan, Robin Wordsworth, Dimitar D Sasselov
Recent findings suggest that Mars may have been a clement environment for the emergence of life and may even have compared favorably to Earth in this regard. These findings have revived interest in the hypothesis that prebiotically important molecules or even nascent life may have formed on Mars and been transferred to Earth. UV light plays a key role in prebiotic chemistry. Characterizing the early martian surface UV environment is key to understanding how Mars compares to Earth as a venue for prebiotic chemistry...
May 24, 2017: Astrobiology
https://www.readbyqxmd.com/read/28520475/kombucha-multimicrobial-community-under-simulated-spaceflight-and-martian-conditions
#2
O Podolich, I Zaets, O Kukharenko, I Orlovska, O Reva, L Khirunenko, M Sosnin, A Haidak, S Shpylova, E Rabbow, M Skoryk, M Kremenskoy, R Demets, N Kozyrovska, J-P de Vera
Kombucha microbial community (KMC) produces a cellulose-based biopolymer of industrial importance and a probiotic beverage. KMC-derived cellulose-based pellicle film is known as a highly adaptive microbial macrocolony-a stratified community of prokaryotes and eukaryotes. In the framework of the multipurpose international astrobiological project "BIOlogy and Mars Experiment (BIOMEX)," which aims to study the vitality of prokaryotic and eukaryotic organisms and the stability of selected biomarkers in low Earth orbit and in a Mars-like environment, a cellulose polymer structural integrity will be assessed as a biomarker and biotechnological nanomaterial...
May 2017: Astrobiology
https://www.readbyqxmd.com/read/28520474/survival-of-deinococcus-geothermalis-in-biofilms-under-desiccation-and-simulated-space-and-martian-conditions
#3
Jan Frösler, Corinna Panitz, Jost Wingender, Hans-Curt Flemming, Petra Rettberg
Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions...
May 2017: Astrobiology
https://www.readbyqxmd.com/read/28520473/a-new-method-and-mass-spectrometric-instrument-for-extraterrestrial-microbial-life-detection-using-the-elemental-composition-analyses-of-martian-regolith-and-permafrost-ice
#4
G G Managadze, A A Safronova, K A Luchnikov, E A Vorobyova, N S Duxbury, P Wurz, N G Managadze, A E Chumikov, R Kh Khamizov
We propose a new technique for the detection of microorganisms by elemental composition analyses of a sample extracted from regolith, permafrost, and ice of extraterrestrial bodies. We also describe the design of the ABIMAS instrument, which consists of the onboard time-of-flight laser mass-reflectron (TOF LMR) and the sample preparation unit (SPU) for biomass extraction. This instrument was initially approved to fly on board the ExoMars 2020 lander mission. The instrument can be used to analyze the elemental composition of possible extraterrestrial microbial communities and compare it to that of terrestrial microorganisms...
May 2017: Astrobiology
https://www.readbyqxmd.com/read/28520472/a-study-of-the-microbial-spatial-heterogeneity-of-bahamian-thrombolites-using-molecular-biochemical-and-stable-isotope-analyses
#5
Artemis S Louyakis, Jennifer M Mobberley, Brooke E Vitek, Pieter T Visscher, Paul D Hagan, R Pamela Reid, Reinhard Kozdon, Ian J Orland, John W Valley, Noah J Planavsky, Giorgio Casaburi, Jamie S Foster
Thrombolites are buildups of carbonate that exhibit a clotted internal structure formed through the interactions of microbial mats and their environment. Despite recent advances, we are only beginning to understand the microbial and molecular processes associated with their formation. In this study, a spatial profile of the microbial and metabolic diversity of thrombolite-forming mats of Highborne Cay, The Bahamas, was generated by using 16S rRNA gene sequencing and predictive metagenomic analyses. These molecular-based approaches were complemented with microelectrode profiling and in situ stable isotope analysis to examine the dominant taxa and metabolic activities within the thrombolite-forming communities...
May 2017: Astrobiology
https://www.readbyqxmd.com/read/28459604/magnesium-sulfate-salt-solutions-and-ices-fail-to-protect-serratia-liquefaciens-from-the-biocidal-effects-of-uv-irradiation-under-martian-conditions
#6
Rebecca L Mickol, Jessica L Page, Andrew C Schuerger
The growth of Serratia liquefaciens has been demonstrated under martian conditions of 0.7 kPa (7 mbar), 0°C, and CO2-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 MgSO4 solutions, or frozen brines, and exposed to terrestrial (i.e., 101.3 kPa, 24°C, O2/N2-normal atmosphere) or martian (i.e., 0...
May 2017: Astrobiology
https://www.readbyqxmd.com/read/28443722/reflections-on-o2-as-a-biosignature-in-exoplanetary-atmospheres
#7
Victoria S Meadows
Oxygenic photosynthesis is Earth's dominant metabolism, having evolved to harvest the largest expected energy source at the surface of most terrestrial habitable zone planets. Using CO2 and H2O-molecules that are expected to be abundant and widespread on habitable terrestrial planets-oxygenic photosynthesis is plausible as a significant planetary process with a global impact. Photosynthetic O2 has long been considered particularly robust as a sign of life on a habitable exoplanet, due to the lack of known "false positives"-geological or photochemical processes that could also produce large quantities of stable O2...
April 26, 2017: Astrobiology
https://www.readbyqxmd.com/read/28422534/in-situ-sampling-of-relative-dust-devil-particle-loads-and-their-vertical-grain-size-distributions
#8
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/28418707/liquid-water-restricts-habitability-in-extreme-deserts
#9
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
#10
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
#11
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
#12
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
#13
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/28409237/prevalence-of-sucretolerant-bacteria-in-common-soils-and-their-isolation-and-characterization
#14
Casper Fredsgaard, Donald B Moore, Fei Chen, Benton C Clark, Mark A Schneegurt
Sucretolerant microbes grow in the presence of sugar concentrations high enough to substantially lower water activities. Natural habitats high in sugars are mainly limited to dried fruit, floral nectar, honey, sugarcane, and associated soils. Organisms that tolerate extremes of solute concentration, high enough to lower water activities, might not be expected in common oligoosmotic soils. We report on the isolation of sucretolerant bacteria from common soils using media supplemented with 50% sucrose (a w 0...
April 13, 2017: Antonie Van Leeuwenhoek
https://www.readbyqxmd.com/read/28323483/taphonomy-of-microbial-biosignatures-in-spring-deposits-a-comparison-of-modern-quaternary-and-jurassic-examples
#15
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
#16
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
#17
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/28323456/stratosphere-conditions-inactivate-bacterial-endospores-from-a-mars-spacecraft-assembly-facility
#18
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/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
#19
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
#20
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
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