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https://www.readbyqxmd.com/read/29156444/survival-of-microbes-in-earth-s-stratosphere
#1
REVIEW
Priya DasSarma, Shiladitya DasSarma
The remarkable survival of microorganisms high above the surface of the Earth is of increasing interest. At stratospheric levels, multiple stressors including ultraviolet and ionizing radiation, low temperatures, hypobaric conditions, extreme desiccation, and nutrient scarcity are all significant challenges. Our understanding of which microorganisms are capable of tolerating such stressful conditions has been addressed by stratospheric sample collection and survival assays, through launching and recovery, and exposure to simulated conditions in the laboratory...
November 17, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/29148825/on-the-growth-and-detectability-of-land-plants-on-habitable-planets-around-m-dwarfs
#2
Duo Cui, Feng Tian, Yuwei Wang, Changshen Li, Chaoqing Yu, Le Yu
One signature of life on Earth is the vegetation red edge (VRE) feature of land plants, a dramatic change of reflectivity at wavelength near 0.7 μm. Potentially habitable planets around M dwarfs are tidally locked, which can limit the distribution of land plants. In this study, we used a biogeochemical model to investigate the distribution of land plants on potentially habitable planets around M dwarfs driven by climate data produced in a general circulation model (GCM). When considering the effects of clouds, the observation time needed for VRE detection on nearby p = 1 exoplanets around nearby M dwarfs is on the order of days using a 25 m(2) telescope if a large continent faces Earth during observations...
November 17, 2017: Astrobiology
https://www.readbyqxmd.com/read/29148823/space-dust-collisions-as-a-planetary-escape-mechanism
#3
Arjun Berera
It is observed that hypervelocity space dust, which is continuously bombarding Earth, creates immense momentum flows in the atmosphere. Some of this fast space dust inevitably will interact with the atmospheric system, transferring energy and moving particles around, with various possible consequences. This paper examines, with supporting estimates, the possibility that by way of collisions the Earth-grazing component of space dust can facilitate planetary escape of atmospheric particles, whether they are atoms and molecules that form the atmosphere or larger-sized particles...
November 17, 2017: Astrobiology
https://www.readbyqxmd.com/read/29146666/students-in-fully-online-programs-report-more-positive-attitudes-toward-science-than-students-in-traditional-in-person-programs
#4
Viranga Perera, Chris Mead, Sanlyn Buxner, David Lopatto, Lev Horodyskyj, Steven Semken, Ariel D Anbar
Following the growth of online, higher-education courses, academic institutions are now offering fully online degree programs. Yet it is not clear how students who enroll in fully online degree programs are similar to those students who enroll in in-person ("traditional") degree programs. Because previous work has shown students' attitudes toward science can affect their performance in a course, it is valuable to ask how attitudes toward science differ between these two populations. We studied students who completed a fully online astrobiology course...
2017: CBE Life Sciences Education
https://www.readbyqxmd.com/read/29135301/microbialite-biosignature-analysis-by-mesoscale-x-ray-fluorescence-%C3%AE-xrf-mapping
#5
Michael M Tice, Kimbra Quezergue, Michael C Pope
As part of its biosignature detection package, the Mars 2020 rover will carry PIXL, the Planetary Instrument for X-ray Lithochemistry, a spatially resolved X-ray fluorescence (μXRF) spectrometer. Understanding the types of biosignatures detectable by μXRF and the rock types μXRF is most effective at analyzing is therefore an important goal in preparation for in situ Mars 2020 science and sample selection. We tested mesoscale chemical mapping for biosignature interpretation in microbialites. In particular, we used μXRF to identify spatial distributions and associations between various elements ("fluorescence microfacies") to infer the physical, biological, and chemical processes that produced the observed compositional distributions...
November 2017: Astrobiology
https://www.readbyqxmd.com/read/29135300/something-new-astrobiology-in-the-real-world
#6
Margaret S Race
No abstract text is available yet for this article.
November 2017: Astrobiology
https://www.readbyqxmd.com/read/29135299/oxygen-free-biochemistry-the-putative-chn-foundation-for-exotic-life-in-a-hydrocarbon-world
#7
Kong-Peng Lv, Lucy Norman, Yi-Liang Li
Since Earth's biochemistry is carbon-based and water-borne, the main strategies for searching for life elsewhere are "follow the carbon" and "follow the water." Recently, however, there is a growing focus on the prospect that putative exotic life on other planets could rely on unearthly biochemistries. Here, we hypothesize a novel oxygen-free organic chemistry for supporting potential exotic biosystems, which is named CHN biochemistry. This oxygen-free CHN biochemistry starts from simple oxygen-free species (including hydrocarbons, hydrogen cyanide, and nitriles) and produces a range of functional macromolecules that may function in similar ways to terran macromolecules, such as sugars (cyanosugars), acids (cyanoacids), amino acids (amino cyanoacids), and nucleobases (cyanonucleobases)...
November 2017: Astrobiology
https://www.readbyqxmd.com/read/29133444/exploring-astrobiology-using-in-silico-molecular-structure-generation
#8
REVIEW
Markus Meringer, H James Cleaves
The origin of life is typically understood as a transition from inanimate or disorganized matter to self-organized, 'animate' matter. This transition probably took place largely in the context of organic compounds, and most approaches, to date, have focused on using the organic chemical composition of modern organisms as the main guide for understanding this process. However, it has gradually come to be appreciated that biochemistry, as we know it, occupies a minute volume of the possible organic 'chemical space'...
December 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29116818/pure-and-oxidized-copper-materials-as-potential-antimicrobial-surfaces-for-spaceflight-activities
#9
C Hahn, M Hans, C Hein, R L Mancinelli, F Mücklich, R Wirth, P Rettberg, C E Hellweg, R Moeller
Microbial biofilms can lead to persistent infections and degrade a variety of materials, and they are notorious for their persistence and resistance to eradication. During long-duration space missions, microbial biofilms present a danger to crew health and spacecraft integrity. The use of antimicrobial surfaces provides an alternative strategy for inhibiting microbial growth and biofilm formation to conventional cleaning procedures and the use of disinfectants. Antimicrobial surfaces contain organic or inorganic compounds, such as antimicrobial peptides or copper and silver, that inhibit microbial growth...
November 8, 2017: Astrobiology
https://www.readbyqxmd.com/read/29106312/nitrogen-concentrations-and-isotopic-compositions-of-seafloor-altered-terrestrial-basaltic-glass-implications-for-astrobiology
#10
G E Bebout, N R Banerjee, M R M Izawa, K Kobayashi, K Lazzeri, L A Ranieri, E Nakamura
Observed enrichments of N (and the δ(15)N of this N) in volcanic glasses altered on Earth's modern and ancient seafloor are relevant in considerations of modern global N subduction fluxes and ancient life on Earth, and similarly altered glasses on Mars and other extraterrestrial bodies could serve as valuable tracers of biogeochemical processes. Palagonitized glasses and whole-rock samples of volcanic rocks on the modern seafloor (ODP Site 1256D) contain 3-18 ppm N with δ(15)Nair values of up to +4.5‰...
November 6, 2017: Astrobiology
https://www.readbyqxmd.com/read/29072614/a-statistical-approach-to-illustrate-the-challenge-of-astrobiology-for-public-outreach
#11
Frédéric Foucher, Keyron Hickman-Lewis, Frances Westall, André Brack
In this study, we attempt to illustrate the competition that constitutes the main challenge of astrobiology, namely the competition between the probability of extraterrestrial life and its detectability. To illustrate this fact, we propose a simple statistical approach based on our knowledge of the Universe and the Milky Way, the Solar System, and the evolution of life on Earth permitting us to obtain the order of magnitude of the distance between Earth and bodies inhabited by more or less evolved past or present life forms, and the consequences of this probability for the detection of associated biosignatures...
October 26, 2017: Life
https://www.readbyqxmd.com/read/29058452/investigation-of-the-geochemical-preservation-of-ca-3-0-ga-permineralized-and-encapsulated-microfossils-by-nanoscale-secondary-ion-mass-spectrometry
#12
Frédéric Delarue, François Robert, Kenichiro Sugitani, Romain Tartèse, Rémi Duhamel, Sylvie Derenne
Observations of Archean organic-walled microfossils suggest that their fossilization took place through both encapsulation and permineralization. In this study, we investigated microfossils from the ca. 3.0 Ga Farrel Quartzite (Pilbara, Western Australia) using transmitted light microscopy, scanning electron microscopy, Raman microspectrometry, and nanoscale secondary ion mass spectrometry (NanoSIMS) ion microprobe analyses. In contrast to previous studies, we demonstrated that permineralized microfossils were not characterized by the micrometric spatial relationships between Si and C-N as observed in thin sections...
October 23, 2017: Astrobiology
https://www.readbyqxmd.com/read/29048224/the-power-of-self-skepticism-in-astrobiology
#13
Shawn D Domagal-Goldman
No abstract text is available yet for this article.
October 2017: Astrobiology
https://www.readbyqxmd.com/read/29048223/laboratory-investigations-on-the-survival-of-bacillus-subtilis-spores-in-deliquescent-salt-mars-analog-environments
#14
Danielle L Nuding, Raina V Gough, Kasthuri J Venkateswaran, James A Spry, Margaret A Tolbert
Observed features such as recurring slope lineae suggest that liquid water may exist on the surface and near-subsurface of Mars today. The presence of this liquid water, likely in the form of a brine, has important implications for the present-day water cycle, habitability, and planetary protection policies. It is possible that this water is formed, at least partially, by deliquescence of salts, a process during which hygroscopic salts absorb water vapor from the atmosphere and form a saturated liquid brine...
October 2017: Astrobiology
https://www.readbyqxmd.com/read/29048222/correlations-between-life-detection-techniques-and-implications-for-sampling-site-selection-in-planetary-analog-missions
#15
Diana M Gentry, Elena S Amador, Morgan L Cable, Nosheen Chaudry, Thomas Cullen, Malene B Jacobsen, Gayathri Murukesan, Edward W Schwieterman, Adam H Stevens, Amanda Stockton, George Tan, Chang Yin, David C Cullen, Wolf Geppert
We conducted an analog sampling expedition under simulated mission constraints to areas dominated by basaltic tephra of the Eldfell and Fimmvörðuháls lava fields (Iceland). Sites were selected to be "homogeneous" at a coarse remote sensing resolution (10-100 m) in apparent color, morphology, moisture, and grain size, with best-effort realism in numbers of locations and replicates. Three different biomarker assays (counting of nucleic-acid-stained cells via fluorescent microscopy, a luciferin/luciferase assay for adenosine triphosphate, and quantitative polymerase chain reaction (qPCR) to detect DNA associated with bacteria, archaea, and fungi) were characterized at four nested spatial scales (1 m, 10 m, 100 m, and >1 km) by using five common metrics for sample site representativeness (sample mean variance, group F tests, pairwise t tests, and the distribution-free rank sum H and u tests)...
October 2017: Astrobiology
https://www.readbyqxmd.com/read/29042301/towards-a-first-implementation-of-the-wlimes-approach-in-living-system-studies-advancing-the-diagnostics-and-therapy-in-personalized-medicine
#16
Plamen L Simeonov
The goal of this paper is to advance an extensible theory of living systems using an approach to biomathematics and biocomputation that suitably addresses self-organized, self-referential and anticipatory systems with multi-temporal multi-agents. Our first step is to provide foundations for modelling of emergent and evolving dynamic multi-level organic complexes and their sustentative processes in artificial and natural life systems. Main applications are in life sciences, medicine, ecology and astrobiology, as well as robotics, industrial automation, man-machine interface and creative design...
October 16, 2017: Bio Systems
https://www.readbyqxmd.com/read/29039682/on-the-habitability-of-desert-varnish-a-combined-study-by-micro-raman-spectroscopy-x-ray-diffraction-and-methylated-pyrolysis-gas-chromatography-mass-spectrometry
#17
C Malherbe, I B Hutchinson, R Ingley, A Boom, A S Carr, H Edwards, B Vertruyen, B Gilbert, G Eppe
In 2020, the ESA ExoMars and NASA Mars 2020 missions will be launched to Mars to search for evidence of past and present life. In preparation for these missions, terrestrial analog samples of rock formations on Mars are studied in detail in order to optimize the scientific information that the analytical instrumentation will return. Desert varnishes are thin mineral coatings found on rocks in arid and semi-arid environments on Earth that are recognized as analog samples. During the formation of desert varnishes (which takes many hundreds of years), organic matter is incorporated, and microorganisms may also play an active role in the formation process...
November 2017: Astrobiology
https://www.readbyqxmd.com/read/29023147/nitrogen-oxides-in-early-earth-s-atmosphere-as-electron-acceptors-for-life-s-emergence
#18
Michael L Wong, Benjamin D Charnay, Peter Gao, Yuk L Yung, Michael J Russell
We quantify the amount of nitrogen oxides (NOx) produced through lightning and photochemical processes in the Hadean atmosphere to be available in the Hadean ocean for the emergence of life. Atmospherically generated nitrate (NO3(-)) and nitrite (NO2(-)) are the most attractive high-potential electron acceptors for pulling and enabling crucial redox reactions of autotrophic metabolic pathways at submarine alkaline hydrothermal vents. The Hadean atmosphere, dominated by CO2 and N2, will produce nitric oxide (NO) when shocked by lightning...
October 12, 2017: Astrobiology
https://www.readbyqxmd.com/read/29019413/instrumentation-for-testing-whether-the-icy-moons-of-the-gas-and-ice-giants-are-inhabited
#19
Julian Chela-Flores
Evidence of life beyond Earth may be closer than we think, given that the forthcoming missions to the Jovian system will be equipped with instruments capable of probing Europa's icy surface for possible biosignatures, including chemical biomarkers, despite the strong radiation environment. Geochemical biomarkers may also exist beyond Europa on icy moons of the gas giants. Sulfur is proposed as a reliable geochemical biomarker for approved and forthcoming missions to the outer solar system. Key Words: JUICE mission-Clipper mission-Geochemical biomarkers-Europa-Moons of the ice giants-Geochemistry-Mass spectrometry...
October 11, 2017: Astrobiology
https://www.readbyqxmd.com/read/29016195/critical-assessment-of-analytical-techniques-in-the-search-for-biomarkers-on-mars-a-mummified-microbial-mat-from-antarctica-as-a-best-case-scenario
#20
Yolanda Blanco, Ignacio Gallardo-Carreño, Marta Ruiz-Bermejo, Fernando Puente-Sánchez, Erika Cavalcante-Silva, Antonio Quesada, Olga Prieto-Ballesteros, Víctor Parro
The search for biomarkers of present or past life is one of the major challenges for in situ planetary exploration. Multiple constraints limit the performance and sensitivity of remote in situ instrumentation. In addition, the structure, chemical, and mineralogical composition of the sample may complicate the analysis and interpretation of the results. The aim of this work is to highlight the main constraints, performance, and complementarity of several techniques that have already been implemented or are planned to be implemented on Mars for detection of organic and molecular biomarkers on a best-case sample scenario...
October 2017: Astrobiology
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