The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
P. Ehrenfreund - One of the best experts on this subject based on the ideXlab platform.
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a contamination assessment of the ci Carbonaceous Meteorite orgueil using a dna directed approach
Meteoritics & Planetary Science, 2016Co-Authors: Joost W Aerts, P. Ehrenfreund, Andreas Elsaesser, Wilfred F M RolingAbstract:The Orgueil Meteorite has become one of the most well-studied Carbonaceous Meteorites, after it fell in France 150 yr ago. Extraterrestrial organic compounds such as amino acids and nucleobases in the parts per billion ranges were identified in Orgueil samples with supporting isotopic analyses. However, speculations of terrestrial contamination such as organic inclusions in the form of microbes and seeds accompanied the analyses of the Orgueil Meteorite ever since its fall. By using molecular analysis, we performed DNA extractions and spiking experiments combined with 16S and 18S rRNA gene targeted PCR amplification to quantify the level of terrestrial biocontamination. Our results indicate that terrestrial contamination with DNA was insignificant in the investigated Meteorite fraction. We also remeasured and confirmed concentrations of amino acids found in previous studies and conclude that their rather high concentrations and distribution cannot be explained by terrestrial contamination with microorganisms alone. These results represent the first analysis using DNA-directed tools in the analysis of the Orgueil Meteorite to determine trace levels of biomarkers.
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Interstellar and Meteoritic Organic Matter at 3.4 μm
Symposium - International Astronomical Union, 1992Co-Authors: P. Ehrenfreund, F. Robert, L. D'hendecourt, F. BeharAbstract:The 3 micron spectrum of the galactic center source IRS 7 is compared to a spectrum obtained on the deuterium-rich organic polymer extracted from the Orgueil Carbonaceous Meteorite. The almost perfect match between the two spectra in the 3.4 μm region suggests that the chemical composition of the interstellar organic matter resembles that of the meteoritic macromolecule.
Sandra Pizzarello - One of the best experts on this subject based on the ideXlab platform.
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the chemistry of life s origin a Carbonaceous Meteorite perspective
Accounts of Chemical Research, 2006Co-Authors: Sandra PizzarelloAbstract:Carbonaceous chondrite Meteorites are primitive asteroidal fragments that contain organic carbon and offer a glimpse of the abiotic chemical processes that preceded the onset of life. Their organic material displays structures as diverse as kerogen-like macromolecules and simpler soluble compounds that range from polar amino acids and polyols to nonpolar hydrocarbons. Several of these compounds have identical counterparts in terrestrial biomolecules and some of the amino acids show a unique l-asymmetry, suggesting their possible contribution to terrestrial molecular evolution and the origin of biological homochirality.
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Chiral Analyses of Organic Compounds in Carbonaceous Meteorites
2004Co-Authors: Sandra PizzarelloAbstract:Contents include the following: 1. Characterization of Tagish Lake organic content. The first two grant years were largely devoted to the molecular and isotopic analyses of Tagish Lake organic composition. This Carbonaceous Meteorite fell in Canada in the winter of the year 2000, and its exceptional atmospheric entry and subsequent recovery (e. g., the sample was recovered and stored by avoiding hand contact and above freezing temperatures) contributed in providing a rare and pristine extraterrestrial material. 2. Chiral analyses of Murchison and Murray soluble organics. One of the most intriguing finding in regard to soluble Meteorite organics is the presence within the amino acid suite of some compounds displaying L-enantiomeric excesses. This configuration is exclusive in the amino acids of terrestrial proteins and the finding has raised speculations of a possible role of amino acids from Meteorites in the origin of homochirality on the early Earth. The main objective for this NASA funding was the characterization of enantiomeric excesses in Meteorites and we have conducted several studies toward establishing their distribution and indignity.
Joost W Aerts - One of the best experts on this subject based on the ideXlab platform.
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a contamination assessment of the ci Carbonaceous Meteorite orgueil using a dna directed approach
Meteoritics & Planetary Science, 2016Co-Authors: Joost W Aerts, P. Ehrenfreund, Andreas Elsaesser, Wilfred F M RolingAbstract:The Orgueil Meteorite has become one of the most well-studied Carbonaceous Meteorites, after it fell in France 150 yr ago. Extraterrestrial organic compounds such as amino acids and nucleobases in the parts per billion ranges were identified in Orgueil samples with supporting isotopic analyses. However, speculations of terrestrial contamination such as organic inclusions in the form of microbes and seeds accompanied the analyses of the Orgueil Meteorite ever since its fall. By using molecular analysis, we performed DNA extractions and spiking experiments combined with 16S and 18S rRNA gene targeted PCR amplification to quantify the level of terrestrial biocontamination. Our results indicate that terrestrial contamination with DNA was insignificant in the investigated Meteorite fraction. We also remeasured and confirmed concentrations of amino acids found in previous studies and conclude that their rather high concentrations and distribution cannot be explained by terrestrial contamination with microorganisms alone. These results represent the first analysis using DNA-directed tools in the analysis of the Orgueil Meteorite to determine trace levels of biomarkers.
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A contamination assessment of the CI Carbonaceous Meteorite Orgueil using a DNA‐directed approach
Meteoritics & Planetary Science, 2016Co-Authors: Joost W Aerts, Andreas Elsaesser, Wilfred F M Roling, Pascale EhrenfreundAbstract:The Orgueil Meteorite has become one of the most well-studied Carbonaceous Meteorites, after it fell in France 150 yr ago. Extraterrestrial organic compounds such as amino acids and nucleobases in the parts per billion ranges were identified in Orgueil samples with supporting isotopic analyses. However, speculations of terrestrial contamination such as organic inclusions in the form of microbes and seeds accompanied the analyses of the Orgueil Meteorite ever since its fall. By using molecular analysis, we performed DNA extractions and spiking experiments combined with 16S and 18S rRNA gene targeted PCR amplification to quantify the level of terrestrial biocontamination. Our results indicate that terrestrial contamination with DNA was insignificant in the investigated Meteorite fraction. We also remeasured and confirmed concentrations of amino acids found in previous studies and conclude that their rather high concentrations and distribution cannot be explained by terrestrial contamination with microorganisms alone. These results represent the first analysis using DNA-directed tools in the analysis of the Orgueil Meteorite to determine trace levels of biomarkers.
Philipp R Heck - One of the best experts on this subject based on the ideXlab platform.
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interstellar residence times of presolar sic dust grains from the murchison Carbonaceous Meteorite
The Astrophysical Journal, 2009Co-Authors: Sachiko Amari, E Zinner, Philipp R Heck, F Gyngard, M M M Meier, J N Avila, R S Lewis, H Baur, R WielerAbstract:The time span between the formation of presolar grains in stellar outflows and their incorporation into early solar-system solids is poorly constrained. Knowledge of this time span is essential for a better understanding of the processing of grains in the interstellar medium (ISM) and formation processes of the solar system. Here, we report interstellar residence times of ~3-1100 Myr for large (~5-50 μm) presolar SiC grains, based on their content of He and Ne produced by Galactic cosmic rays. A majority of these grains have interstellar residence times on the order of a few tens up to less than 200 Myr, considerably shorter than theoretical estimates of interstellar dust lifetimes (~500 Myr), but long enough to require formation of the majority of the grains before that of the presolar molecular cloud. The age distribution may be explained by starburst activity 1-2 billion years prior to the birth of the Sun. Our findings provide essential "ground truth" to constrain models of interstellar dust lifetimes and destructive processes in the ISM.
Michael N Mautner - One of the best experts on this subject based on the ideXlab platform.
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biological potential of extraterrestrial materials 2 microbial and plant responses to nutrients in the murchison Carbonaceous Meteorite
Icarus, 1997Co-Authors: Michael N Mautner, A J Conner, K Killham, David W DeamerAbstract:Abstract Meteoritic materials are investigated as potential early planetary nutrients. Aqueous extracts of the Murchison C2 Carbonaceous Meteorite are utilized as a sole carbon source by microorganisms, as demonstrated by the genetically modified Pseudomonas fluorescence equipped with the lux gene. Nutrient effects are observed also with the soil microorganisms Nocardia asteroides and Arthrobacter pascens that reach populations up to 5 × 10 7 CFU/ml in Meteorite extracts, similar to populations in terrestrial soil extracts. Plant tissue cultures of Asparagus officinalis and Solanum tuberosum (potato) exhibit enhanced pigmentation and some enhanced growth when Meteorite extracts are added to partial nutrient media, but inhibited growth when added to full nutrient solution. The Meteorite extracts lead to large increases in S, Ca, Mg, and Fe plant tissue contents as shown by X-ray fluorescence, while P, K, and Cl contents show mixed effects. In both microbiological and plant tissue experiments, the nutrient and inhibitory effects appear to be best balanced for growth at about 1:20 (extracted solid:H 2 O) ratios. The results suggest that solutions in cavities in Meteorites can provide efficient concentrated biogenic and early nutrient environments, including high phosphate levels, which may be the limiting nutrient. The results also suggest that Carbonaceous asteroid resources can sustain soil microbial activity and provide essential macronutrients for future space-based eco- systems.