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2.
Geobiology ; 17(6): 691-707, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31478592

RESUMO

On rocky planets such as Earth and Mars the serpentinization of olivine in ultramafic crust produces hydrogen that can act as a potential energy source for life. Direct evidence of fluid-rock interaction on Mars comes from iddingsite alteration veins found in martian meteorites. In the Yamato 000593 meteorite, putative biosignatures have been reported from altered olivines in the form of microtextures and associated organic material that have been compared to tubular bioalteration textures found in terrestrial sub-seafloor volcanic rocks. Here, we use a suite of correlative, high-sensitivity, in situ chemical, and morphological analyses to characterize and re-evaluate these microalteration textures in Yamato 000593, a clinopyroxenite from the shallow subsurface of Mars. We show that the altered olivine crystals have angular and micro-brecciated margins and are also highly strained due to impact-induced fracturing. The shape of the olivine microalteration textures is in no way comparable to microtunnels of inferred biological origin found in terrestrial volcanic glasses and dunites, and rather we argue that the Yamato 000593 microtextures are abiotic in origin. Vein filling iddingsite extends into the olivine microalteration textures and contains amorphous organic carbon occurring as bands and sub-spherical concentrations <300 nm across. We propose that a martian impact event produced the micro-brecciated olivine crystal margins that reacted with subsurface hydrothermal fluids to form iddingsite containing organic carbon derived from abiotic sources. These new data have implications for how we might seek potential biosignatures in ultramafic rocks and impact craters on both Mars and Earth.


Assuntos
Meio Ambiente Extraterreno/química , Compostos de Ferro/química , Compostos de Magnésio/química , Marte , Meteoroides , Silicatos/química , Exobiologia
3.
Trans Am Clin Climatol Assoc ; 130: 200-211, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31516184

RESUMO

The Hubble Space Telescope has been in Earth orbit for almost 30 years, returning an amazing variety of scientific discoveries. It can be pointed via ground command to the entire panoply of astronomical objects, from nearby targets in our solar system to the most distant objects in the known universe. While these wonderful scientific results were expected by the project's founders, what have been more surprising are the cultural aspects of the program. Hubble has been embraced by the general public to an extent unprecedented for complex scientific facilities. Not only are its images widely known for their beauty, but the project itself has repeatedly entered the popular lexicon as an example of a technological pinnacle. We present examples of the numerous scientific successes, as well as popular culture memes related to Hubble. Finally, it is also important to ponder the broader question of why we conduct astronomical research.


Assuntos
Astronomia , Cultura , Pesquisa , Galáxias , Humanos , Meteoroides , Cultura Popular , Sistema Solar
4.
Chem Commun (Camb) ; 55(71): 10563-10566, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31417990

RESUMO

Besides delivering plausible prebiotic feedstock molecules and high-energy initiators, extraterrestrial impacts could also affect the process of abiogenesis by altering the early Earth's geological environment in which primitive life was conceived. We show that iron-rich smectites formed by reprocessing of basalts due to the residual post-impact heat could catalyze the synthesis and accumulation of important prebiotic building blocks such as nucleobases, amino acids and urea.


Assuntos
Argila/química , Ferro/química , Meteoroides , Silicatos/química , Aminoácidos/química , Catálise , Evolução Química , Meio Ambiente Extraterreno/química , Origem da Vida , Ureia/química
5.
PLoS One ; 14(7): e0218750, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31260466

RESUMO

This study presents multiwall and bamboo-like carbon nanotubes found in samples from the Allende carbonaceous chondrite using high-resolution transmission electron microscopy (HRTEM). A highly disordered lattice observed in this material suggests the presence of chiral domains in it. Our results also show amorphous and poorly-graphitized carbon, nanodiamonds, and onion-like fullerenes. The presence of multiwall and bamboo-like carbon nanotubes have important implications for hypotheses that explain how a probable source of asymmetry in carbonaceous chondrites might have contributed to the enantiomeric excess in soluble organics under extraterrestrial scenarios. This is the first study proving the existence of carbon nanotubes in carbonaceous chondrites.


Assuntos
Meio Ambiente Extraterreno , Meteoroides , Nanodiamantes/ultraestrutura , Nanotubos de Carbono/ultraestrutura , Fulerenos/química , México , Microscopia Eletrônica de Transmissão , Nanodiamantes/química , Nanotubos de Carbono/química
7.
Orig Life Evol Biosph ; 49(1-2): 1-18, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31004318

RESUMO

Syntheses under shock in nitrogen bubbled samples of the water - formamide - bicarbonate - sodium hydroxide system at pH 8.63, 9.46 and 10.44 were performed in the stainless steel preservation capsules. The maximum temperature and pressure in the capsules reached 545 K and 12.5 GPa respectively. Using the LC-MS-MS analysis, the 21 synthesis products have been identified, including amines and polyamines, carboxamide, acetamide and urea derivatives, compounds containing aniline, pyrrolidine, pyrrole, imidazole, as well as alcohol groups. It was found that the Fischer-Tropsch-type syntheses with catalysis on the surface of the stainless steel of the conservation capsule associated with the adsorbed hydrogen cyanide reactions and transamidation processes play the main role in the shock syntheses. Formation reactions of all the above-mentioned compounds have been suggested. It was proposed that hydrogen cyanide, ammonia, isocyanic acid, aminonitrile, aminoacetonitrile, as well as adsorbed species H(a), CH(a), CH2(a), CHOH(a), NH2(a) and H2CNH(a) are especially important for the formation of the products. A reduction reaction of adsorbed bicarbonate with hydrogen to formaldehyde has been first postulated. In the studied system also classical reactions take place - Wöhler's synthesis of urea and Butlerov's synthesis of methenamine. It was suggest that material of meteorites may be an effective catalyst in the Fischer-Tropsch-type syntheses at falling of the iron-nickel meteorites in the water - formamide regions on the early Earth. It was concluded that life could have originated due to the impact of meteorites on alkaline water-formamide lakes located near volcanoes on the early Earth.


Assuntos
Bicarbonatos/química , Evolução Química , Formamidas/química , Origem da Vida , Compostos de Potássio/química , Hidróxido de Sódio/química , Cromatografia Líquida , Concentração de Íons de Hidrogênio , Meteoroides , Espectrometria de Massas em Tandem , Água/química
8.
Proc Jpn Acad Ser B Phys Biol Sci ; 95(4): 165-177, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30971619

RESUMO

A comprehensive geochemical study of the Chelyabinsk meteorite reveals further details regarding its history of impact-related fragmentation and melting, and later aqueous alteration, during its transit toward Earth. We support an ∼30 Ma age obtained by Ar-Ar method (Beard et al., 2014) for the impact-related melting, based on Rb-Sr isotope analyses of a melt domain. An irregularly shaped olivine with a distinct O isotope composition in a melt domain appears to be a fragment of a silicate-rich impactor. Hydrogen and Li concentrations and isotopic compositions, textures of Fe oxyhydroxides, and the presence of organic materials located in fractures, are together consistent with aqueous alteration, and this alteration could have pre-dated interaction with the Earth's atmosphere. As one model, we suggest that hypervelocity capture of the impact-related debris by a comet nucleus could have led to shock-wave-induced supercritical aqueous fluids dissolving the silicate, metallic, and organic matter, with later ice sublimation yielding a rocky rubble pile sampled by the meteorite.


Assuntos
Meteoroides , Água/química , Evolução Planetária
10.
Life Sci Space Res (Amst) ; 20: 20-29, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30797431

RESUMO

Titan is the largest moon of Saturn and possesses a dense atmosphere composed of nitrogen and methane. Various types of organic compounds (hydrocarbons, nitriles, etc.) have been found on Titan, which were generated by reactions taking place in its atmosphere. These reactions are considered to provide crucial evidence for chemical reactions which may have occurred in the atmosphere of primitive Earth. Cassini discovered several lakes of liquid methane and ethane on Titan's surface; in addition, the presence of ammonia water in its sub-surface was implied. In order to simulate the chemical reactions in Titan's atmosphere, gas mixtures of nitrogen and methane have been exposed to plasma discharges to synthesize complex organic matters. In this study, we focused on the formation of nucleic acid bases and related compounds recovered from synthesized Titan tholins. The five nucleic acid bases that terrestrial life uses (adenine, cytosine, thymine, guanine, and uracil) have already been reported to be present in synthesized Titan tholins. Purines and pyrimidines, including the five aforementioned nucleic acid bases, were extracted from synthesized Titan tholins and analyzed by HPLC and LC/MS. As a result, the pyrimidine bases of isocytosine and 2, 4-diaminopyrimidine were detected together with the terrestrial nucleic acid bases of adenine, uracil, and cytosine. The results obtained in conjunction with those from previous studies show that some nucleic acid bases and related pyrimidine bases are found in synthesized Titan tholins, suggesting that chemical evolutions toward xenogenetic systems could occur in Titan's environment.


Assuntos
Atmosfera , Ácidos Nucleicos/análise , Ácidos Nucleicos/química , Compostos Orgânicos/análise , Purinas/análise , Pirimidinas/análise , Saturno , Meio Ambiente Extraterreno , Meteoroides
11.
Nature ; 565(7739): 278-279, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30647423
12.
Artigo em Inglês | MEDLINE | ID: mdl-30195928

RESUMO

Confocal Raman spectroscopy is effective in unveiling structures of minerals without destruction from surface to certain depth. In this study, we introduce an application of confocal Raman spectroscopy on minerals in a primitive chondritic meteorite. The experimental lateral resolution on silicate minerals in this study is ~1.0 µm. Raman spectrum of mesostasis in a named "Tear Drop" chondrule, a spherule object from a primitive chondrite, of Elephant Moraine 14017 (EET 14017) shows a broad feature indicating amorphous phase, which is a common characteristic of primitive chondrule mesostasis. Weak intensities of 825 and 858 cm-1 peaks were observed in the glassy mesostasis, probably originated from olivine below the surface. A plagioclase-rich chondrule (PRC-1) of EET 14017 was investigated with Raman spectroscopy, which contains two different occurrences of plagioclase: lath-shaped and interstitial grains. The strong intensity of 488 and 505 cm-1 (plagioclase) and weak intensity of 461 cm-1 band were observed on the lath-shaped plagioclase. The weak 461 cm-1 peak from the plagioclase is probably from the subsurface quartz. Raman spectrum of interstital plagioclase in PRC-1 shows 488 and 505 cm-1 bands and weak pyroxene bands. Depth profiling conducted on the interstitial plagioclase clearly shows that pyroxene exists below the surface. High-lateral resolution and well-resolved depth profiling with the confocal Raman spectroscopy allows us to identify tiny grains and investigate hidden phases underneath the surface without destruction of extraterrestrial materials.


Assuntos
Meteoroides , Minerais/análise , Análise Espectral Raman/métodos , Silicatos/análise , Propriedades de Superfície
14.
Electrophoresis ; 39(22): 2898-2905, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30229957

RESUMO

The importance of microorganisms and biotechnology in space exploration and future planets colonization has been discussed in the literature. Meteorites are interesting samples to study microbe-mineral interaction focused on space exploration. The chemolithotropic bacterium Acidithiobacillus ferrooxidans has been used as model to understand the iron and sulfur oxidation. In this work, capillary electrophoresis with capacitively coupled contactless conductivity detection and UV detection was used to monitor bacterial growth in a meteorite simulant by measuring the conversion of Fe2+ into Fe+3 . The effect of Co2+ and Ni2+ (metals also found in meteorites) on the bacterial growth was also evaluated. The presented method allowed the analyses of all metals in a single run (less than 8 min). The background electrolyte was composted of 10 mmol/L α-hydroxyisobutyric acid/Histidine. For comparison purpose, the samples were also analyzed by UV-Vis spectrophotometry. The Fe2+ conversion into Fe3+ by A. ferrooxidans was observed up to 36 h with the growth rate constant of 0.19/h and 0.21/h in Tuovinen and Kelly (T&K) and in meteorite simulant media, respectively. The developed method presents favorable prospect to monitor the growth of other chemolithotropic microorganisms for biotechnology applications.


Assuntos
Acidithiobacillus/metabolismo , Eletroforese Capilar/métodos , Meteoroides , Acidithiobacillus/química , Crescimento Quimioautotrófico , Ferro/análise , Ferro/metabolismo , Oxirredução , Reprodutibilidade dos Testes , Espectrofotometria Ultravioleta , Sulfetos/análise , Sulfetos/metabolismo
15.
Astrobiology ; 18(11): 1479-1496, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30129781

RESUMO

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. Alternatively, these or other catalytic groups can be searched for on non-amino-acid organic molecules, which can be tested for certain hydrolytic catalytic activities. The first scenario assumes that life may have originated in a similar manner as the terrestrial set of α-amino acids, while the second scenario does not set such a requirement. From the catalytic propensity perspective proposed in the first scenario, life must have invented amino acids with high catalytic propensity (His, Cys, Arg) in order to overcome, and be complemented by, the low catalytic propensity of the initially available abiogenic amino acids. The abiogenic and the metabolically invented amino acids with the lowest catalytic propensity can also serve as markers of extraterrestrial life when searching for patterns on the basis of the following functional propensities related to protein secondary/quaternary structure: (1) amino acids that are able to form α-helical intramembrane peptide domains, which can serve as primitive transporters in protocell membrane bilayers and catalysts of simple biochemical reactions; (2) amino acids that tend to accumulate in extremophile proteins of Earth and possibly extraterrestrial life. The catalytic/structural functional propensity approach offers a new perspective in the search for extraterrestrial life and could help unify previous amino acid-based approaches.


Assuntos
Aminoácidos/química , Biomarcadores/química , Exobiologia , Meio Ambiente Extraterreno , Catálise , Meteoroides , Oligopeptídeos/química , Estrutura Secundária de Proteína , Tensoativos/química
16.
Sci Rep ; 8(1): 8833, 2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29891867

RESUMO

Magnetochiral phenomena may be responsible for the selection of chiral states of biomolecules in meteoric environments. For example, the Supernova Amino Acid Processing (SNAAP) Model was proposed previously as a possible mode of magnetochiral selection of amino acids by way of the weak interaction in strong magnetic fields. In earlier work, this model was shown to produce an enantiomeric excess (ee) as high as 0.014% for alanine. In this paper we present the results of molecular quantum chemistry calculations from which ees are determined for the α-amino acids plus isovaline and norvaline, which were found to have positive ees in meteorites. Calculations are performed for both isolated and aqueous states. In some cases, the aqueous state was found to produce larger ees reaching values as high as a few percent under plausible conditions.


Assuntos
Aminoácidos/química , Evolução Química , Meio Ambiente Extraterreno , Meteoroides , Origem da Vida , Estereoisomerismo , Campos Magnéticos , Modelos Teóricos
17.
Astrobiology ; 18(8): 1041-1056, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29638146

RESUMO

Potential martian molecular targets include those supplied by meteoritic carbonaceous chondrites such as amino acids and polycyclic aromatic hydrocarbons and true biomarkers stemming from any hypothetical martian biota (organic architectures that can be directly related to once living organisms). Heat extraction and pyrolysis-based methods currently used in planetary exploration are highly aggressive and very often modify the target molecules making their identification a cumbersome task. We have developed and validated a mild, nondestructive, multiplex inhibitory microarray immunoassay and demonstrated its implementation in the SOLID (Signs of Life Detector) instrument for simultaneous detection of several nonvolatile life- and nonlife-derived organic molecules relevant in planetary exploration and environmental monitoring. By utilizing a set of highly specific antibodies that recognize D- or L- aromatic amino acids (Phe, Tyr, Trp), benzo[a]pyrene (B[a]P), pentachlorophenol, and sulfone-containing aromatic compounds, respectively, the assay was validated in the SOLID instrument for the analysis of carbon-rich samples used as analogues of the organic material in carbonaceous chondrites or even Mars samples. Most of the antibodies enabled sensitivities at the 1-10 ppb level and some even at the ppt level. The multiplex immunoassay allowed the detection of B[a]P as well as aromatic sulfones in a water/methanol extract of an Early Cretaceous lignite sample (c.a., 140 Ma) representing type IV kerogen. No L- or D-aromatic amino acids were detected, reflecting the advanced diagenetic stage and the fossil nature of the sample. The results demonstrate the ability of the liquid extraction by ultrasonication and the versatility of the multiplex inhibitory immunoassays in the SOLID instrument to discriminate between organic matter derived from life and nonlife processes, an essential step toward life detection outside Earth.


Assuntos
Exobiologia , Imunoensaio/métodos , Meteoroides , Compostos Orgânicos/análise , Planetas , Aminoácidos Aromáticos/análise , Anticorpos/análise , Benzo(a)pireno/química , Calibragem , Modelos Moleculares , Volatilização
20.
Sci Adv ; 4(1): eaao3521, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29349297

RESUMO

Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life's precursor molecules such as amino acids. The organic compounds also contain a mixture of C-, O-, and N-bearing macromolecular carbon materials exhibiting a wide range of structural order, as well as aromatic, ketone, imine, and/or imidazole compounds. The enrichment in 15N is comparable to the organic matter in pristine Renazzo-type carbonaceous chondrites, which reflects the sources of interstellar 15N, such as ammonia and amino acids. The amino acid content of the Zag halite deviates from the meteorite matrix, supporting an exogenic origin of the halite, and therefore, the Zag meteorite contains organics synthesized on two distinct parent bodies. Our study suggests that the asteroidal parent body where the halite precipitated, potentially asteroid 1 Ceres, shows evidence for a complex combination of biologically and prebiologically relevant molecules.


Assuntos
Meio Ambiente Extraterreno , Compostos Orgânicos/química , Sais/química , Água/química , Aminoácidos/análise , Cristalização , Isótopos , Meteoroides , Análise Espectral Raman , Espectroscopia por Absorção de Raios X
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