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Tiago Alves Jorge de Souza, Tiago Campos Pereira
One of the most important laboratory animal species is the nematode Caenorhabditis elegans, which has been used in a range of research fields such as neurobiology, body development, and molecular biology. The scientific progress obtained by employing C. elegans as a model in these areas has encouraged its use in new fields. One of the new potential applications concerns the biological responses to hyperacceleration stress (g-force), but only a few studies have evaluated the response of multicellular organisms to extreme hypergravity conditions at the order of magnitude 105  x g, which is the theorized force experienced by rocks ejected from Mars (or similar planets)...
May 10, 2018: Astrobiology
Victoria S Meadows, Christopher T Reinhard, Giada N Arney, Mary N Parenteau, Edward W Schwieterman, Shawn D Domagal-Goldman, Andrew P Lincowski, Karl R Stapelfeldt, Heike Rauer, Shiladitya DasSarma, Siddharth Hegde, Norio Narita, Russell Deitrick, Jacob Lustig-Yaeger, Timothy W Lyons, Nicholas Siegler, J Lee Grenfell
We describe how environmental context can help determine whether oxygen (O2 ) detected in extrasolar planetary observations is more likely to have a biological source. Here we provide an in-depth, interdisciplinary example of O2 biosignature identification and observation, which serves as the prototype for the development of a general framework for biosignature assessment. Photosynthetically generated O2 is a potentially strong biosignature, and at high abundance, it was originally thought to be an unambiguous indicator for life...
May 10, 2018: Astrobiology
Nancy Y Kiang, Shawn Domagal-Goldman, Mary N Parenteau, David C Catling, Yuka Fujii, Victoria S Meadows, Edward W Schwieterman, Sara I Walker
The rapid rate of discoveries of exoplanets has expanded the scope of the science possible for the remote detection of life beyond Earth. The Exoplanet Biosignatures Workshop Without Walls (EBWWW) held in 2016 engaged the international scientific community across diverse scientific disciplines, to assess the state of the science and technology in the search for life on exoplanets, and to identify paths for progress. The workshop activities resulted in five major review papers, which provide (1) an encyclopedic review of known and proposed biosignatures and models used to ascertain them (Schwieterman et al...
May 9, 2018: Astrobiology
Richard J Gillams, Tony Z Jia
An increasing body of evidence relates the wide range of benefits mineral surfaces offer for the development of early living systems, including adsorption of small molecules from the aqueous phase, formation of monomeric subunits and their subsequent polymerization, and supramolecular assembly of biopolymers and other biomolecules. Each of these processes was likely a necessary stage in the emergence of life on Earth. Here, we compile evidence that templating and enhancement of prebiotically-relevant self-assembling systems by mineral surfaces offers a route to increased structural, functional, and/or chemical complexity...
May 8, 2018: Life
Edward W Schwieterman, Nancy Y Kiang, Mary N Parenteau, Chester E Harman, Shiladitya DasSarma, Theresa M Fisher, Giada N Arney, Hilairy E Hartnett, Christopher T Reinhard, Stephanie L Olson, Victoria S Meadows, Charles S Cockell, Sara I Walker, John Lee Grenfell, Siddharth Hegde, Sarah Rugheimer, Renyu Hu, Timothy W Lyons
In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its fingerprint on the spectrum of our planet. Aided by the universality of the laws of physics and chemistry, we turn to Earth's biosphere, both in the present and through geologic time, for analog signatures that will aid in the search for life elsewhere...
May 4, 2018: Astrobiology
Catherine D Neish, Ralph D Lorenz, Elizabeth P Turtle, Jason W Barnes, Melissa G Trainer, Bryan Stiles, Randolph Kirk, Charles A Hibbitts, Michael J Malaska
Saturn's moon Titan has all the ingredients needed to produce "life as we know it." When exposed to liquid water, organic molecules analogous to those found on Titan produce a range of biomolecules such as amino acids. Titan thus provides a natural laboratory for studying the products of prebiotic chemistry. In this work, we examine the ideal locales to search for evidence of, or progression toward, life on Titan. We determine that the best sites to identify biological molecules are deposits of impact melt on the floors of large, fresh impact craters, specifically Sinlap, Selk, and Menrva craters...
May 2, 2018: Astrobiology
K B Chin, I Chi, J Pasalic, C-K Huang, Laura M Barge
Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration...
April 2018: Review of Scientific Instruments
Brian M Hynek, Karyn L Rogers, Monique Antunovich, Geoffroy Avard, Guillermo E Alvarado
The Poás volcano in Costa Rica has been studied as a Mars geochemical analog environment, since both the style of hydrothermal alteration present and the alteration mineralogy are consistent with Mars' relict hydrothermal systems. The site hosts an active volcano, with high-temperature fumaroles (up to 980°C) and an ultra-acidic lake. This lake, Laguna Caliente, is one of the most dynamic environments on Earth, with frequent phreatic eruptions, temperatures ranging from near-ambient to almost boiling, a pH range of -1 to 1...
April 24, 2018: Astrobiology
David C Catling, Joshua Krissansen-Totton, Nancy Y Kiang, David Crisp, Tyler D Robinson, Shiladitya DasSarma, Andrew J Rushby, Anthony Del Genio, William Bains, Shawn Domagal-Goldman
Finding life on exoplanets from telescopic observations is an ultimate goal of exoplanet science. Life produces gases and other substances, such as pigments, which can have distinct spectral or photometric signatures. Whether or not life is found with future data must be expressed with probabilities, requiring a framework of biosignature assessment. We present a framework in which we advocate using biogeochemical "Exo-Earth System" models to simulate potential biosignatures in spectra or photometry...
April 20, 2018: Astrobiology
Milan M Ćirković
Jared Diamond's argument against extraterrestrial intelligence from evolutionary contingency is subjected to critical scrutiny. As with the earlier arguments of George Gaylord Simpson, it contains critical loopholes that lead to its unraveling. From the point of view of the contemporary debates about biological evolution, perhaps the most contentious aspect of such arguments is their atemporal and gradualist usage of the space of all possible biological forms (morphospace). Such usage enables the translation of the adaptive value of a trait into the probability of its evolving...
April 20, 2018: Astrobiology
Yoelsy Leyva, Osmel Martín, César R García-Jacas
The ability to support a replicator population in an extremely hostile environment is considered in a simple model of a prebiotic cell. We explore from a classical approach how the replicator viability changes as a function of the cell radius. The model includes the interaction between two different species: a substrate that flows from the exterior and a replicator that feeds on the substrate and is readily destroyed in the environment outside the cell. According to our results, replicators in the cell only exist when the radius exceeds some critical value [Formula: see text] being, in general, a function of the substrate concentration, the diffusion constant of the replicator species, and the reproduction rate coefficient...
April 2018: Astrobiology
Rakesh Mogul, Gregory A Barding, Sidharth Lalla, Sooji Lee, Steve Madrid, Ryan Baki, Mahjabeen Ahmed, Hania Brasali, Ivonne Cepeda, Trevor Gornick, Shawn Gunadi, Nicole Hearn, Chirag Jain, Eun Jin Kim, Thi Nguyen, Vinh Bao Nguyen, Alex Oei, Nicole Perkins, Joseph Rodriguez, Veronica Rodriguez, Gautam Savla, Megan Schmitz, Nicholas Tedjakesuma, Jillian Walker
Spacecraft assembly facilities are oligotrophic and low-humidity environments, which are routinely cleaned using alcohol wipes for benchtops and spacecraft materials, and alkaline detergents for floors. Despite these cleaning protocols, spacecraft assembly facilities possess a persistent, diverse, dynamic, and low abundant core microbiome, where the Acinetobacter are among the dominant members of the community. In this report, we show that several spacecraft-associated Acinetobacter metabolize or biodegrade the spacecraft cleaning reagents of ethanol (ethyl alcohol), 2-propanol (isopropyl alcohol), and Kleenol 30 (floor detergent) under ultraminimal conditions...
April 19, 2018: Astrobiology
Jacob Heinz, Janosch Schirmack, Alessandro Airo, Samuel P Kounaves, Dirk Schulze-Makuch
It is well known that dissolved salts can significantly lower the freezing point of water and thus extend habitability to subzero conditions. However, most investigations thus far have focused on sodium chloride as a solute. In this study, we report on the survivability of the bacterial strain Planococcus halocryophilus in sodium, magnesium, and calcium chloride or perchlorate solutions at temperatures ranging from +25°C to -30°C. In addition, we determined the survival rates of P. halocryophilus when subjected to multiple freeze/thaw cycles...
April 17, 2018: Astrobiology
Sukrit Ranjan, Zoe R Todd, John D Sutherland, Dimitar D Sasselov
A key challenge in origin-of-life studies is understanding the environmental conditions on early Earth under which abiogenesis occurred. While some constraints do exist (e.g., zircon evidence for surface liquid water), relatively few constraints exist on the abundances of trace chemical species, which are relevant to assessing the plausibility and guiding the development of postulated prebiotic chemical pathways which depend on these species. In this work, we combine literature photochemistry models with simple equilibrium chemistry calculations to place constraints on the plausible range of concentrations of sulfidic anions (HS- , HSO3 - , SO3 2- ) available in surficial aquatic reservoirs on early Earth due to outgassing of SO2 and H2 S and their dissolution into small shallow surface water reservoirs like lakes...
April 8, 2018: Astrobiology
Svetlana Shkolyar, Evan J Eshelman, Jack D Farmer, David Hamilton, Michael G Daly, Cody Youngbull
The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies...
April 6, 2018: Astrobiology
Jihua Hao, Elena Giovenco, Ulysse Pedreira-Segade, Gilles Montagnac, Isabelle Daniel
Icy environments may have been common on early Earth due to the faint young sun. Previous studies have proposed that the formation of large icy bodies in the early ocean could concentrate the building blocks of life in eutectic fluids and, therefore, facilitate the polymerization of monomers. This hypothesis is based on the untested assumption that organic molecules are virtually incompatible in ice Ih (hexagonal ice). In this study, we conducted freezing experiments to explore the partitioning behavior of selected amino acids (AAs; glycine, l-alanine, l-proline, and l-phenylalanine) between ice Ih and aqueous solutions analogous to seawater...
April 5, 2018: Astrobiology
John D Rummel, Gerhard Kminek
The last time NASA envisioned a sample return mission from Mars, the development of a protocol to support the analysis of the samples in a containment facility resulted in a "Draft Test Protocol" that outlined required preparations "for the safe receiving, handling, testing, distributing, and archiving of martian materials here on Earth" (Rummel et al., 2002 ). This document comprised a specific protocol to be used to conduct a biohazard test for a returned martian sample, following the recommendations of the Space Studies Board of the US National Academy of Sciences...
April 2018: Astrobiology
Sanjay S Limaye, Rakesh Mogul, David J Smith, Arif H Ansari, Grzegorz P Słowik, Parag Vaishampayan
The lower cloud layer of Venus (47.5-50.5 km) is an exceptional target for exploration due to the favorable conditions for microbial life, including moderate temperatures and pressures (∼60°C and 1 atm), and the presence of micron-sized sulfuric acid aerosols. Nearly a century after the ultraviolet (UV) contrasts of Venus' cloud layer were discovered with Earth-based photographs, the substances and mechanisms responsible for the changes in Venus' contrasts and albedo are still unknown. While current models include sulfur dioxide and iron chloride as the UV absorbers, the temporal and spatial changes in contrasts, and albedo, between 330 and 500 nm, remain to be fully explained...
March 30, 2018: Astrobiology
Wayne L Nicholson, Andrew C Schuerger, Thierry Douki
DNA is considered a potential biomarker for life-detection experiments destined for Mars. Experiments were conducted to examine the photochemistry of bacterial DNA, either unprotected or within Bacillus subtilis spores, in response to exposure to simulated martian surface conditions consisting of the following: temperature (-10°C), pressure (0.7 kPa), atmospheric composition [CO2 (95.54%), N2 (2.7%), Ar (1.6%), O2 (0.13%), and H2 O (0.03%)], and UV-visible-near IR solar radiation spectrum (200-1100 nm) calibrated to 4 W/m2 of UVC (200-280 nm)...
April 2018: Astrobiology
Alexander Ruf, Basem Kanawati, Philippe Schmitt-Kopplin
Dihydroxymagnesium carboxylates [(OH)2 MgO2 CR] were probed for decarboxylation on a theoretical level, by utilizing both Møller-Plesset perturbation theory (MP2) and density functional theory (B3LYP-DFT) computations. This study is connected to the question of whether this recently introduced, astrobiologically relevant chemical class may form Grignard-type reagent molecules. To extract trends for a broad molecular mass range, different linear alkyl chain lengths between C4 and C11 were computed. The forward energy barrier for decarboxylation reactions increases linearly as a function of the ligand's chain length...
March 27, 2018: Journal of Molecular Modeling
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