UV radiation induced DNA damage in marine viruses along a latitudinal gradient in the southeastern Pacific Ocean

UV radiation induced DNA damage (inferred from cyclobutane pyrimidine dimers, CPDs) in native marine virus communities was examined at 12 locations along a latitudinal transect from 41degrees S to 3degrees N in the southeastern Pacific Ocean. Surface waters were collected prior to sunrise each day and placed in UV transparent incubators kept at in situ seawater temperatures. A replicate treatment was prefiltered through a 0.2 mum filter to remove microbial host cells. Both treatments were exposed to ambient solar radiation until approximately 1 h before sunset. At the end of the day, the virus fraction was collected from each sample by filtration and concentration. DNA damage was determined in each fraction and compared to DNA damage in pre-dawn samples as well as DNA dosimeters exposed to an entire solar day's influence. CPDs in dosimeters and integrated solar irradiance were very highly correlated, as was DNA damage in the pre-sunrise virus community and latitude. A reduction in host cell abundance resulted in no consistent pattern or change in the CPD induction of virus particles, suggesting minimal host mediated repair in this natural virus community. The low daily induction of damage in virus incubations combined with the high residual damage suggests that the sunrise damage levels were the result of DNA damage accumulation over numerous days, indicating a long residence time for virus particles in surface waters in this region.