Inclusions in evaporitic minerals sometimes contain remnants of microorganisms or biomarkers, which can be considered as traces of life. Raman spectroscopy with resonance enhancement is one of the best analytical methods to search for such biomarkers in places of interest for astrobiology, including the surface and near subsurface of planet Mars. Portable Raman spectrometers are used as training tools for detection of biomarkers. Investigations of the limits and challenges of detecting biomolecules in crystals using Raman spectroscopy is important because natural occurrences often involve mineral assemblages as well as their fluid and solid inclusions. A portable Raman spectrometer with 532 nm excitation was used for detection of carotenoid biomarkers: salinixanthin of Salinibacter ruber (Bacteroidetes) and α-bacterioruberin of Halorubrum sodomense (Halobacteria) in laboratory-grown artificial inclusions in compound crystals of several chlorides and sulfates, simulating entrapment of microorganisms in evaporitic minerals. Crystals of halite (NaCl), sylvite (KCl), arcanite (K2SO4) and tschermigite ((NH4)Al(SO4)2·12H2O) were grown from synthetic solutions that contained microorganisms. A second crystalline layer of NaCl or K2SO4 was grown subsequently so that primary crystals containing microorganisms are considered as solid inclusions. A portable Raman spectrometer with resonance enabling excitation detected signals of both carotenoid pigments. Correct positions of diagnostic Raman bands corresponding to the specific carotenoids were recorded.
- MeSH
- Bacteria chemistry MeSH
- Chlorides chemistry MeSH
- Exobiology * MeSH
- Carotenoids analysis MeSH
- Crystallization MeSH
- Mars * MeSH
- Prokaryotic Cells chemistry MeSH
- Spectrum Analysis, Raman instrumentation MeSH
- Sulfates chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
People confined to a closed space live in a visual environment that differs from a natural open-space environment in several respects. The view is restricted to no more than a few meters, and nearby objects cannot be perceived relative to the position of a horizon. Thus, one might expect to find changes in visual space perception as a consequence of the prolonged experience of confinement. The subjects in our experimental study were participants of the Mars-500 project and spent nearly a year and a half isolated from the outside world during a simulated mission to Mars. The participants were presented with a battery of computer-based psychophysical tests examining their performance on various 3-D perception tasks, and we monitored changes in their perceptual performance throughout their confinement. Contrary to our expectations, no serious effect of the confinement on the crewmembers' 3-D perception was observed in any experiment. Several interpretations of these findings are discussed, including the possibilities that (1) the crewmembers' 3-D perception really did not change significantly, (2) changes in 3-D perception were manifested in the precision rather than the accuracy of perceptual judgments, and/or (3) the experimental conditions and the group sample were problematic.
- MeSH
- Housing classification MeSH
- Adult MeSH
- Space Flight * MeSH
- Astronauts psychology MeSH
- Humans MeSH
- Mars MeSH
- Judgment physiology MeSH
- Distance Perception physiology MeSH
- Stress, Psychological physiopathology MeSH
- Regression Analysis MeSH
- Social Isolation psychology MeSH
- Space Perception physiology MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Journal Article MeSH
- Clinical Trial MeSH
- Research Support, Non-U.S. Gov't MeSH
Raman spectroscopy is being adopted as a nondestructive instrumentation for the robotic exploration of Mars to search for traces of life in the geological record. Here, miniaturized Raman spectrometers of two different types equipped with 532 and 785 nm lasers for excitation, respectively, were compared for the detection of microbial biomarkers in natural halite from the hyperarid region of the Atacama Desert. Measurements were performed directly on the rock as well as on the homogenized, powdered samples prepared from this material-the effects of this sample preparation and the excitation wavelength employed in the analysis are compared and discussed. From these results, 532 nm excitation was found to be superior for the analysis of powdered specimens due to its high sensitivity toward carotenoids and hence a higher capability for their detection at relatively low concentration in bulk powdered specimens. For the same reason, this wavelength was a better choice for the detection of carotenoids in direct measurements made on the rock samples. The 785 nm excitation wavelength, in contrast, proved to be more sensitive toward the detection of scytonemin.
- Keywords
- molecular adsorbent recirculating system, fractionated plasma separation and adsorption, FPSA, bioeliminační metody, BAL systémy, FPSA,
- MeSH
- Liver Failure, Acute * therapy MeSH
- Bioreactors MeSH
- Hepatocytes MeSH
- Intracranial Pressure MeSH
- Humans MeSH
- Mars MeSH
- Extracorporeal Circulation * instrumentation MeSH
- Swine, Miniature MeSH
- Disease Models, Animal MeSH
- Sorption Detoxification * MeSH
- Liver Transplantation MeSH
- Equipment and Supplies MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
