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1.
Astrobiology ; 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32167834

RESUMO

The detection of biosignatures on Mars is of outstanding interest in the current field of Astrobiology and drives various fields of research, ranging from new sample collection strategies to the development of more sensitive detection techniques. Detailed analysis of the organic content in Mars analog materials collected from extreme environments on Earth improves the current understanding of biosignature preservation and detection under conditions similar to those of Mars. In this article, we examined the biological fingerprint of several locations in the Atacama Desert (Chile), which include different wet and dry, and intermediate to high elevation salt flats (also named salars). Liquid Chromatography and Multidimensional Gas Chromatography Mass Spectrometry measurement techniques were used for the detection and analysis of amino acids extracted from the salt crusts and sediments by using sophisticated extraction procedures. Illumina 16S amplicon sequencing was used for the identification of microbial communities associated with the different sample locations. Although amino acid load and organic carbon and nitrogen quantities were generally low, it was found that most of the samples harbored complex and versatile microbial communities, which were dominated by (extremely) halophilic microorganisms (most notably by species of the Archaeal family Halobacteriaceae). The dominance of salts (i.e., halites and sulfates) in the investigated samples leaves its mark on the composition of the microbial communities but does not appear to hinder the potential of life to flourish since it can clearly adapt to the higher concentrations. Although the Atacama Desert is one of the driest and harshest environments on Earth, it is shown that there are still sub-locations where life is able to maintain a foothold, and, as such, salt flats could be considered as interesting targets for future life exploration missions on Mars.

2.
J Chromatogr A ; 1487: 248-253, 2017 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-28139224

RESUMO

This work presents the development of a simple and efficient analytical protocol for the direct enantioselective resolution of sugars. A racemic mixture of the C3 sugar d,l-glyceraldehyde and the C5 monosaccharides d,l-arabinose, d,l-ribose, d,l-xylose, and d,l-lyxose was subjected to derivatization with trifluoroacetic anhydride, and corresponding derivatives were separated on a ß-cyclodextrin column with excellent resolution factors. Even though each aldopentose shows beside the linear form four predominant cyclic hemiacetals being the α- and ß-furanose along with the α- and ß-pyranose, we show that the overall enantiomeric excess of each compound can be precisely determined. Moreover, the measured detection limit for derivatized aldopentoses ranges from 0.015 to 0.019pmol on the column, while the quantification limit varies from 0.5 to 0.64pmol on the column.


Assuntos
Cromatografia Gasosa/métodos , Monossacarídeos/análise , Arabinose/análise , Arabinose/isolamento & purificação , Monossacarídeos/química , Monossacarídeos/isolamento & purificação , Pentoses/análise , Pentoses/isolamento & purificação , Ribose/análise , Ribose/isolamento & purificação , Estereoisomerismo , Xilose/análise , Xilose/isolamento & purificação
3.
Science ; 355(6321): 141, 2017 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-28082555

RESUMO

We detected ribose and related sugars in the organic residues of simulated interstellar ices using multidimensional gas chromatography. Kawai questions the formation of sugar compounds in the ices and suggests that they arise from a classical formose reaction during sample workup for analysis. We disagree with this hypothesis and present additional data to argue that Kawai's criticism does not apply.


Assuntos
Gelo/análise , Ribose , Meio Ambiente Extraterreno , Compostos Orgânicos , Raios Ultravioleta
4.
Phys Chem Chem Phys ; 18(18): 12696-706, 2016 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-27095534

RESUMO

Photoelectron circular dichroism (PECD) manifests itself as an intense forward/backward asymmetry in the angular distribution of photoelectrons produced from randomly-oriented enantiomers by photoionization with circularly-polarized light (CPL). As a sensitive probe of both photoionization dynamics and of the chiral molecular potential, PECD attracts much interest especially with the recent performance of related experiments with visible and VUV laser sources. Here we report, by use of quasi-perfect CPL VUV synchrotron radiation and using a double imaging photoelectron/photoion coincidence (i(2)PEPICO) spectrometer, new and very accurate values of the corresponding asymmetries on showcase chiral isomers: camphor and fenchone. These data have additionally been normalized to the absolute enantiopurity of the sample as measured by a chromatographic technique. They can therefore be used as benchmarking data for new PECD experiments, as well as for theoretical models. In particular we found, especially for the outermost orbital of both molecules, a good agreement with CMS-Xα PECD modeling over the whole VUV range. We also report a spectacular sensitivity of PECD to isomerism for slow electrons, showing large and opposite asymmetries when comparing R-camphor to R-fenchone (respectively -10% and +16% around 10 eV). In the course of this study, we could also assess the analytical potential of PECD. Indeed, the accuracy of the data we provide are such that limited departure from perfect enantiopurity in the sample we purchased could be detected and estimated in excellent agreement with the analysis performed in parallel via a chromatographic technique, establishing a new standard of accuracy, in the ±1% range, for enantiomeric excess measurement via PECD. The i(2)PEPICO technique allows correlating PECD measurements to specific parent ion masses, which would allow its application to analysis of complex mixtures.

5.
Science ; 352(6282): 208-12, 2016 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-27124456

RESUMO

Ribose is the central molecular subunit in RNA, but the prebiotic origin of ribose remains unknown. We observed the formation of substantial quantities of ribose and a diversity of structurally related sugar molecules such as arabinose, xylose, and lyxose in the room-temperature organic residues of photo-processed interstellar ice analogs initially composed of H2O, CH3OH, and NH3 Our results suggest that the generation of numerous sugar molecules, including the aldopentose ribose, may be possible from photochemical and thermal treatment of cosmic ices in the late stages of the solar nebula. Our detection of ribose provides plausible insights into the chemical processes that could lead to formation of biologically relevant molecules in suitable planetary environments.


Assuntos
Radiação Cósmica , Gelo , Origem da Vida , RNA/química , Ribose/síntese química , Ácido Acético/química , Amônia/química , Arabinose/síntese química , Meio Ambiente Extraterreno , Meteoroides , Pentoses/síntese química , Processos Fotoquímicos , Raios Ultravioleta , Xilose/síntese química
6.
J Chromatogr A ; 1433: 131-6, 2016 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-26803906

RESUMO

This work presents an improved analytical procedure for the resolution and quantification of amino acid enantiomers by multidimensional gas chromatography. The procedure contains a derivatization step, by which amino acids were transformed into N(O,S)-ethoxycarbonylheptafluorobutyl esters. It was optimized for the resolution of non-proteinogenic amino acids in the matrix of complex non-terrestrial samples. The procedure has proven to be highly sensitive and shows a wide linearity range with 0.005-3 pmol detection limits for quantitative determinations. The developed procedure was tested on a sample of the Murchison meteorite, for which obtained chromatograms show excellent peak resolution, minimal co-elution and peak overlap. We conclude that comprehensive two dimensional chromatography, in combination with the optimized derivatization method is a highly suitable technique for the analysis of samples with very limited quantities and containing potentially prebiotic molecules, such as interstellar ice analogs and meteorites.


Assuntos
Aminoácidos/isolamento & purificação , Meteoroides , Cromatografia Gasosa/métodos , Estereoisomerismo
7.
Proc Natl Acad Sci U S A ; 112(4): 965-70, 2015 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-25583475

RESUMO

Evolved interstellar ices observed in dense protostellar molecular clouds may arguably be considered as part of precometary materials that will later fall on primitive telluric planets, bringing a wealth of complex organic compounds. In our laboratory, experiments reproducing the photo/thermochemical evolution of these ices are routinely performed. Following previous amino acid identifications in the resulting room temperature organic residues, we have searched for a different family of molecules of potential prebiotic interest. Using multidimensional gas chromatography coupled to time-of-flight mass spectrometry, we have detected 10 aldehydes, including the sugar-related glycolaldehyde and glyceraldehyde--two species considered as key prebiotic intermediates in the first steps toward the synthesis of ribonucleotides in a planetary environment. The presence of ammonia in water and methanol ice mixtures appears essential for the recovery of these aldehydes in the refractory organic residue at room temperature, although these products are free of nitrogen. We finally point out the importance of detecting aldehydes and sugars in extraterrestrial environments, in the gas phase of hot molecular clouds, and, more importantly, in comets and in primitive meteorites that have most probably seeded the Earth with organic material as early as 4.2 billion years ago.

8.
Angew Chem Int Ed Engl ; 54(5): 1402-12, 2015 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-25431250

RESUMO

Life, as it is known to us, uses exclusively L-amino acid and D-sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry-breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the "chirality module" on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus.

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