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Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium ChroococcidiopsisThe effect of X-ray irradiation on cell survival, induction, and repair of DNA damage was studied by using 10 Chroococcidiopsis strains isolated from desert and hypersaline environments. After exposure to 2.5 kGy, the percentages of survival for the strains ranged from 80 to 35%. In the four most resistant strains, the levels of survival were reduced by 1 or 2 orders of magnitude after irradiation with 5 kGy; viable cells were recovered after exposure to 15 kGy but not after exposure to 20 kGy. The severe DNA damage evident after exposure to 2.5 kGy was repaired within 3 h, and the severe DNA damage evident after exposure to 5 kGy was repaired within 24 h. The increase in trichloroacetic acid-precipitable radioactivity in the culture supernatant after irradiation with 2.5 kGy might have been due to cell lysis and/or an excision process involved in DNA repair. The radiation resistance of Chroococcidiopsis strains may reflect the ability of these cyanobacteria to survive prolonged desiccation through efficient repair of the DNA damage that accumulates during dehydration.
Document ID
Document Type
Reprint (Version printed in journal)
Billi, D. (Florida State University Tallahassee, Florida 32306-1100, United States)
Friedmann, E. I.
Hofer, K. G.
Caiola, M. G.
Ocampo-Friedmann, R.
Date Acquired
August 22, 2013
Publication Date
April 1, 2000
Publication Information
Publication: Applied and environmental microbiology
Volume: 66
Issue: 4
ISSN: 0099-2240
Subject Category
Life Sciences (General)
Distribution Limits
Non-NASA Center
NASA Discipline Exobiology