TY - JOUR
T1 - Molecular assessment of UVC radiation-induced DNA damage repair in the stromatolitic halophilic archaeon, Halococcus hamelinensis
AU - Leuko, S.
AU - Neilan, B. A.
AU - Burns, B. P.
AU - Walter, M. R.
AU - Rothschild, L. J.
PY - 2011/2/7
Y1 - 2011/2/7
N2 - The halophilic archaeon Halococcus hamelinensis was isolated from living stromatolites in Shark Bay, Western Australia, that are known to be exposed to extreme conditions of salinity, desiccation, and UV radiation. Modern stromatolites are considered analogues of very early life on Earth and thus inhabitants of modern stromatolites, and Hcc. hamelinensis in particular, are excellent candidates to examine responses to high UV radiation. This organism was exposed to high dosages (up to 500 J/m2) of standard germicidal UVC (254 nm) radiation and overall responses such as survival, thymine-thymine cyclobutane pyrimidine dimer formation, and DNA repair have been assessed. Results show that Hcc. hamelinensis is able to survive high UVC radiation dosages and that intact cells give an increased level of DNA protection over purified DNA. The organism was screened for the bacterial-like nucleotide excision repair (NER) genes uvrA, uvrB, uvrC, as well as for the photolyase phr2 gene. All four genes were discovered and changes in the expression levels of those genes during repair in either light or dark were investigated by means of quantitative Real-Time (qRT) PCR. The data obtained and presented in this study show that the uvrA, uvrB, and uvrC genes were up-regulated during both repair conditions. The photolyase phr2 was not induced during dark repair, yet showed a 20-fold increase during repair in light conditions. The data presented is the first molecular study of different repair mechanisms in the genus Halococcus following exposure to high UVC radiation levels.
AB - The halophilic archaeon Halococcus hamelinensis was isolated from living stromatolites in Shark Bay, Western Australia, that are known to be exposed to extreme conditions of salinity, desiccation, and UV radiation. Modern stromatolites are considered analogues of very early life on Earth and thus inhabitants of modern stromatolites, and Hcc. hamelinensis in particular, are excellent candidates to examine responses to high UV radiation. This organism was exposed to high dosages (up to 500 J/m2) of standard germicidal UVC (254 nm) radiation and overall responses such as survival, thymine-thymine cyclobutane pyrimidine dimer formation, and DNA repair have been assessed. Results show that Hcc. hamelinensis is able to survive high UVC radiation dosages and that intact cells give an increased level of DNA protection over purified DNA. The organism was screened for the bacterial-like nucleotide excision repair (NER) genes uvrA, uvrB, uvrC, as well as for the photolyase phr2 gene. All four genes were discovered and changes in the expression levels of those genes during repair in either light or dark were investigated by means of quantitative Real-Time (qRT) PCR. The data obtained and presented in this study show that the uvrA, uvrB, and uvrC genes were up-regulated during both repair conditions. The photolyase phr2 was not induced during dark repair, yet showed a 20-fold increase during repair in light conditions. The data presented is the first molecular study of different repair mechanisms in the genus Halococcus following exposure to high UVC radiation levels.
KW - Astrobiology
KW - DNA damage
KW - Halophilic archaea
KW - Repair mechanisms
KW - UVC radiation
UR - http://www.scopus.com/inward/record.url?scp=78651440098&partnerID=8YFLogxK
U2 - 10.1016/j.jphotobiol.2010.10.002
DO - 10.1016/j.jphotobiol.2010.10.002
M3 - Article
C2 - 21074452
AN - SCOPUS:78651440098
VL - 102
SP - 140
EP - 145
JO - Journal of Photochemistry and Photobiology B: Biology
JF - Journal of Photochemistry and Photobiology B: Biology
SN - 1011-1344
IS - 2
ER -