Biology
Scientific paper
Jun 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005asbio...5..127c&link_type=abstract
Astrobiology, Volume 5, Issue 2, pp. 127-140.
Biology
35
Mars, Simulated Uv Flux, Chroococcidiopsis, Cyanobacterium
Scientific paper
Dried monolayers of Chroococcidiopsis sp. 029, a desiccation-tolerant, endolithic cyanobacterium, were exposed to a simulated martian-surface UV and visible light flux, which may also approximate to the worst-case scenario for the Archean Earth. After 5 min, there was a 99% loss of cell viability, and there were no survivors after 30 min. However, this survival was approximately 10 times higher than that previously reported for Bacillus subtilis. We show that under 1 mm of rock, Chroococcidiopsis sp. could survive (and potentially grow) under the high martian UV flux if water and nutrient requirements for growth were met. In isolated cells, phycobilisomes and esterases remained intact hours after viability was lost. Esterase activity was reduced by 99% after a 1-h exposure, while 99% loss of autofluorescence required a 4-h exposure. However, cell morphology was not changed, and DNA was still detectable by 4',6-diamidino-2-phenylindole staining after an 8-h exposure (equivalent to approximately 1 day on Mars at the equator). Under 1 mm of simulant martian soil or gneiss, the effect of UV radiation could not be detected on esterase activity or autofluorescence after 4 h. These results show that under the intense martian UV flux the morphological signatures of life can persist even after viability, enzymatic activity, and pigmentation have been destroyed. Finally, the global dispersal of viable, isolated cells of even this desiccation-tolerant, ionizing-radiation-resistant microorganism on Mars is unlikely as they are killed quickly by unattenuated UV radiation when in a desiccated state. These findings have implications for the survival of diverse microbial contaminants dispersed during the course of human exploratory class missions on the surface of Mars.
Billi Daniela
Cockell Charles S.
Friedmann Imre E.
Panitz Corinna
Schuerger Andrew C.
No associations
LandOfFree
Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-869412