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Astrobiology

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https://www.readbyqxmd.com/read/30431334/an-apparent-binary-choice-in-biochemistry-mutual-reactivity-implies-life-chooses-thiols-or-nitrogen-sulfur-bonds-but-not-both
#1
Janusz J Petkowski, William Bains, Sara Seager
A fundamental goal of biology is to understand the rules behind life's use of chemical space. Established work focuses on why life uses the chemistry that it does. Given the enormous scope of possible chemical space, we postulate that it is equally important to ask why life largely avoids certain areas of chemical space. The nitrogen-sulfur bond is a prime example, as it rarely appears in natural molecules, despite the very rich N-S bond chemistry applied in various branches of industry (e.g., industrial materials, agrochemicals, pharmaceuticals)...
November 15, 2018: Astrobiology
https://www.readbyqxmd.com/read/30431329/organization-and-compartmentalization-by-lipid-membranes-promote-reactions-related-to-the-origin-of-cellular-life
#2
Constantinos M Paleos
Liquid crystals have certain physical properties that promote chemical reactions which cannot occur in bulk phase media. These properties are displayed, among other molecules, by amphiphilic compounds which assemble into membrane structures then concentrate and organize biologically relevant monomers within their confined spaces. When mixtures of lipids and nucleotides are cycled multiple times between hydrated and anhydrous conditions, the monomers polymerize in the dry phase into oligonucleotides. Upon rehydration, mixtures of the polymers are encapsulated in lipid-bounded compartments called protocells...
November 15, 2018: Astrobiology
https://www.readbyqxmd.com/read/30407074/wind-driven-saltation-an-overlooked-challenge-for-life-on-mars
#3
E N Bak, M G Larsen, S K Jensen, P Nørnberg, R Moeller, K Finster
Numerous studies have demonstrated that the martian surface environment is hostile to life because of its rough radiation climate and the reactive chemistry of the regolith. Physical processes such as erosion and transport of mineral particles by wind-driven saltation have hitherto not been considered as a life hazard. We report a series of experiments where bacterial endospores (spores of Bacillus subtilis) were exposed to a simulated saltating martian environment. We observed that 50% of the spores that are known to be highly resistant to radiation and oxidizing chemicals were destroyed by saltation-mediated abrasion within one minute...
November 8, 2018: Astrobiology
https://www.readbyqxmd.com/read/30383981/detection-of-fungi-from-low-biomass-spacecraft-assembly-clean-room-aerosols
#4
Ying Zhang, Cong-Xin Xin, Lan-Tao Zhang, Yu-Lin Deng, Xiang Wang, Xiang-Yu Chen, Zhao-Qian Wang
Highly sensitive and rapid detection of airborne fungi in space stations is essential to ensure disease prevention and equipment safety. In this study, quantitative loop-mediated isothermal amplification (qLAMP) was used to detect fungi in the aerosol of the low-biomass environment of China's space station assembly clean room (CSSAC). A qLAMP primer set for detecting a wide range of aerosol fungi was developed by aligning 34 sequences of isolated fungal species and 17 space station aerosol-related fungal species...
November 1, 2018: Astrobiology
https://www.readbyqxmd.com/read/30383399/on-the-rate-of-abiogenesis-from-a-bayesian-informatics-perspective
#5
Jingjing Chen, David Kipping
Life appears to have emerged relatively quickly on the Earth, a fact sometimes used to justify a high rate of spontaneous abiogenesis (λ) among Earth-like worlds. Conditioned upon a single datum-the time of earliest evidence for life (tobs )-previous Bayesian formalisms for the posterior distribution of λ have demonstrated how inferences are highly sensitive to the priors. Rather than attempt to infer the true λ posterior, we here compute the relative change to λ when new experimental/observational evidence is introduced...
October 31, 2018: Astrobiology
https://www.readbyqxmd.com/read/30383392/lichen-as-micro-ecosystem-extremophilic-behavior-with-astrobiotechnological-applications
#6
Athina Parasyri, Aikaterini Papazi, Nikolaos Stamatis, Sotirios Zerveas, Evangelia V Avramidou, Andreas G Doulis, Stergios Pirintsos, Kiriakos Kotzabasis
This work demonstrates the tolerance of lichen Pleurosticta acetabulum under extreme conditions similar to those encountered in extraterrestrial environments. Specifically, the impact of three extreme Mars-like conditions-complete dehydration, extremely low temperature (-196°C/77K), and oxygen depletion-on lichens was investigated. The symbiosis of mycobiont and photobiont partners creates a micro-ecosystem that ensures viability of both symbiotic partners under prolonged desiccation and extremely low temperatures without any cultivation care...
October 31, 2018: Astrobiology
https://www.readbyqxmd.com/read/30376361/survival-dna-and-ultrastructural-integrity-of-a-cryptoendolithic-antarctic-fungus-in-mars-and-lunar-rock-analogues-exposed-outside-the-international-space-station
#7
Silvano Onofri, Laura Selbmann, Claudia Pacelli, Laura Zucconi, Elke Rabbow, Jean-Pierre de Vera
The search for life beyond Earth involves investigation into the responses of model organisms to the deleterious effects of space. In the frame of the BIOlogy and Mars Experiment, as part of the European Space Agency (ESA) space mission EXPOSE-R2 in low Earth orbit (LEO), dried colonies of the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515 were grown on martian and lunar analog regolith pellets, and exposed for 16 months to LEO space and simulated Mars-like conditions on the International Space Station...
October 30, 2018: Astrobiology
https://www.readbyqxmd.com/read/30339033/basalt-a-basaltic-terrains-in-idaho-and-hawaii-as-planetary-analogues-for-mars-geology-and-astrobiology
#8
Scott S Hughes, Christopher W Haberle, Shannon E Kobs Nawotniak, Alexander Sehlke, W Brent Garry, Richard C Elphic, Samuel J Payler, Adam H Stevens, Charles S Cockell, Allyson L Brady, Jennifer L Heldmann, Darlene S S Lim
Field research target regions within two basaltic geologic provinces are described as Earth analogues to Mars. Regions within the eastern Snake River Plain of Idaho and the Big Island of Hawaii, the United States, provinces that represent analogues of present-day and early Mars, respectively, were evaluated on the basis of geologic settings, rock lithology and geochemistry, rock alteration, and climate. Each of these factors provides rationale for the selection of specific targets for field research in five analog target regions: (1) Big Craters and (2) Highway lava flows at Craters of the Moon National Monument and Preserve, Idaho, and (3) Mauna Ulu low shield, (4) Kīlauea Iki lava lake, and (5) Kīlauea caldera in the Kīlauea Volcano summit region and the East Rift Zone of Hawaii...
October 19, 2018: Astrobiology
https://www.readbyqxmd.com/read/30346215/the-nasa-roadmap-to-ocean-worlds
#9
Amanda R Hendrix, Terry A Hurford, Laura M Barge, Michael T Bland, Jeff S Bowman, William Brinckerhoff, Bonnie J Buratti, Morgan L Cable, Julie Castillo-Rogez, Geoffrey C Collins, Serina Diniega, Christopher R German, Alexander G Hayes, Tori Hoehler, Sona Hosseini, Carly J A Howett, Alfred S McEwen, Catherine D Neish, Marc Neveu, Tom A Nordheim, G Wesley Patterson, D Alex Patthoff, Cynthia Phillips, Alyssa Rhoden, Britney E Schmidt, Kelsi N Singer, Jason M Soderblom, Steven D Vance
In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to "identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find...
October 13, 2018: Astrobiology
https://www.readbyqxmd.com/read/30251886/tunnel-formation-in-basalt-glass
#10
Martin R Fisk, Radu Popa, David Wacey
We propose a model whereby microscopic tunnels form in basalt glass in response to a natural proton flux from seawater into the glass. This flux is generated by the alteration of the glass as protons from water replace cations in the glass. In our proton gradient model, cells are gateways through which protons enter and alter the glass and through which cations leave the glass. In the process, tunnels are formed, and cells derive energy from the proton and ion fluxes. Proton flux from seawater into basalt glass would have occurred on Earth as soon as water accumulated on the surface and would have preceded biological redox catalysis...
September 22, 2018: Astrobiology
https://www.readbyqxmd.com/read/30251874/mars-relevant-field-experiences-in-morocco-the-importance-of-spatial-scales-and-subsurface-exploration
#11
Akos Kereszturi, Zsuzsanna Kapui, Gian Gabrielle Ori, Kamal Taj-Eddine, Gabor Ujvari
During field work at the Ibn Battuta Mars analogue sites, two research questions were analyzed: (1) How do we identify sampling sites using remote and local imaging and (2) what kind of information can be gained from shallow subsurface exploration? While remote images help in targeting field activities in general, the connection between observations at different spatial scales for different rocky desert terrain types is not well established; in this, focused comparison of remote in situ images of well-selected analogues would help a great deal...
September 22, 2018: Astrobiology
https://www.readbyqxmd.com/read/30199267/basalt-the-future-of-mars-on-earth-today
#12
Stanley G Love
No abstract text is available yet for this article.
September 8, 2018: Astrobiology
https://www.readbyqxmd.com/read/30183335/habitable-climate-scenarios-for-proxima-centauri-b-with-a-dynamic-ocean
#13
Anthony D Del Genio, Michael J Way, David S Amundsen, Igor Aleinov, Maxwell Kelley, Nancy Y Kiang, Thomas L Clune
The nearby exoplanet Proxima Centauri b will be a prime future target for characterization, despite questions about its retention of water. Climate models with static oceans suggest that Proxima b could harbor a small dayside surface ocean despite its weak instellation. We present the first climate simulations of Proxima b with a dynamic ocean. We find that an ocean-covered Proxima b could have a much broader area of surface liquid water but at much colder temperatures than previously suggested, due to ocean heat transport and/or depression of the freezing point by salinity...
September 5, 2018: Astrobiology
https://www.readbyqxmd.com/read/30152704/dalangtan-saline-playa-in-a-hyperarid-region-on-tibet-plateau-ii-preservation-of-salts-with-high-hydration-degrees-in-subsurface
#14
Alian Wang, Pablo Sobron, Fanjing Kong, Mianping Zheng, Yu-Yan Sara Zhao
Based on a field expedition to the Dalangtan (DLT) saline playa located in a hyperarid region (Qaidam Basin) on the Tibet Plateau and follow-up investigations, we report the mineralogy and geochemistry of the salt layers in two vertical stratigraphic cross sections in the DLT playa. Na-, Ca-, Mg-, KCaMg-sulfates; Na-, K-, KMg-chlorides; mixed (K, Mg)-chloride-sulfate; and chlorate and perchlorate were identified in the collected samples. This mineral assemblage represents the last-stage precipitation products from Na-K-Mg-Ca-Cl-SO4 brine and the oxychlorine formation from photochemistry reaction similar to other hyperarid regions on Earth...
August 28, 2018: Astrobiology
https://www.readbyqxmd.com/read/30289279/paleolakes-of-northeast-hellas-precipitation-groundwater-fed-and-fluvial-lakes-in-the-navua-hadriacus-ausonia-region-mars
#15
Henrik I Hargitai, Virginia C Gulick, Natalie H Glines
The slopes of northeastern Hellas Basin, Mars exhibit a wide variety of fluvial landforms. In addition to the Dao-Niger-Harmakhis-Reull Valles outflow channels, many smaller channels and valleys cut into this terrain, several of which include discontinuous sections. We have mapped these channels and channel-associated depressions to investigate potential paleolakes from the Navua Valles in the West, through the Hadriacus Mons volcano in the center, to the Ausonia Montes in the East. We have identified three groups of candidate paleolakes at the source regions of major drainages and a fourth paleolake type scattered along the lower reaches of these drainages...
November 2018: Astrobiology
https://www.readbyqxmd.com/read/30289276/environmental-data-and-survival-data-of-deinococcus-aetherius-from-the-exposure-facility-of-the-japan-experimental-module-of-the-international-space-station-obtained-by-the-tanpopo-mission
#16
Akihiko Yamagishi, Yuko Kawaguchi, Hirofumi Hashimoto, Hajime Yano, Eiichi Imai, Satoshi Kodaira, Yukio Uchihori, Kazumichi Nakagawa
The Tanpopo mission has two objectives: (1) test the panspermia hypothesis and (2) test whether organic compounds may have been transferred to Earth before the origin of life. We developed an exposure panel (EP) designed to expose microbes and organic compounds to the space environment and a capture panel designed to capture high-velocity particles on the International Space Station (ISS) using aerogel contained in an aluminum container. The panels returned after 1 year of exposure at the Exposure Facility of the Japan Experimental Module, ISS...
November 2018: Astrobiology
https://www.readbyqxmd.com/read/30289268/comparing-spore-resistance-of-bacillus-strains-isolated-from-hydrothermal-vents-and-spacecraft-assembly-facilities-to-environmental-stressors-and-decontamination-treatments
#17
Vincenzo Zammuto, Felix M Fuchs, Marcel Fiebrandt, Katharina Stapelmann, Nikea J Ulrich, Teresa L Maugeri, Rüdiger Pukall, Concetta Gugliandolo, Ralf Moeller
Submarine hydrothermal vents are inhabited by a variety of microorganisms capable of tolerating environmental extremes, making them ideal candidates to further expand our knowledge of the limitations for terrestrial life, including their ability to survive the exposure of spaceflight-relevant conditions. The spore resistance of two Bacillus spp. strains, APA and SBP3, isolated from two shallow vents off Panarea Island (Aeolian Islands, Italy), to artificial and environmental stressors (i.e., UVC radiation, X-rays, heat, space vacuum, hydrogen peroxide [H2 O2 ], and low-pressure plasma), was compared with that of two close phylogenetic relatives (Bacillus horneckiae and Bacillus oceanisediminis)...
November 2018: Astrobiology
https://www.readbyqxmd.com/read/30230354/superflare-ultraviolet-impact-on-kepler-96-system-a-glimpse-of-habitability-when-the-ozone-layer-first-formed-on-earth
#18
Raissa Estrela, Adriana Valio
Kepler-96 is an active solar-type star harboring a Super-Earth planet in close orbit. Its age of 2.3 gigayears is the same as the Sun when there was a considerable increase of oxygen in Earth's atmosphere due to micro-organisms living in the ocean. We present the analysis of superflares seen on the transit light curves of Kepler-96b. The model used here simulates the planetary transit in a flaring star. By fitting the observational data with this model, it is possible to infer the physical properties of the flares, such as their duration and the energy released...
November 2018: Astrobiology
https://www.readbyqxmd.com/read/30160529/enhancement-and-inhibitory-activities-of-minerals-for-alanine-oligopeptide-elongation-under-hydrothermal-conditions
#19
Kunio Kawamura, Noriko Konagaya, Yoshimi Maruoka
In a previous study, we have showed that the elongation of an alanine oligopeptide [L-alanyl-L-alanyl-L-alanyl-L-alanine ((Ala)4 )] to higher oligopeptides is enhanced by calcite and dolomite at 275°C, using a mineral-mediated hydrothermal flow reactor system. However, a problem during the use of hydrothermal flow reactor system was that some of the minerals, such as clay, could not be tested due to their clogging in the reactor. In this article, we attempted to analyze the scope of enhancement for the formation of L-alanyl-L-alanyl-L-alanyl-L-alanyl-L-alanine ((Ala)5 ) and higher oligopeptides with different minerals including clay minerals for the elongation of alanine oligopeptide at 175°C...
November 2018: Astrobiology
https://www.readbyqxmd.com/read/30129781/functional-properties-of-amino-acid-side-chains-as-biomarkers-of-extraterrestrial-life
#20
Christos D Georgiou
The present study proposes to search our solar system (Mars, Enceladus, Europa) for patterns of organic molecules that are universally associated with biological functions and structures. The functions are primarily catalytic because life could only have originated within volume/space-constrained compartments containing chemical reactions catalyzed by certain polymers. The proposed molecular structures are specific groups in the side chains of amino acids with the highest catalytic propensities related to life on Earth, that is, those that most frequently participate as key catalytic groups in the active sites of enzymes such as imidazole, thiol, guanidinium, amide, and carboxyl...
November 2018: Astrobiology
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