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Aquatic Microbial Ecology

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AME 17:111-120 (1999)  -  doi:10.3354/ame017111

Sunlight-induced DNA damage and resistance in natural viral communities

Markus G. Weinbauer1, Steven W. Wilhelm2,*, Curtis A. Suttle3,**, Ralph J. Pledger4, David L. Mitchell4

1National Research Centre for Biotechnology, Division Microbiology, Mascheroder Weg 1, D-38124 Braunschweig, Germany
2National Water Research Institute, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario L7R 4A6, Canada
3Departments of Earth and Ocean Sciences (Oceanography), Botany, and Microbiology and Immunology, The University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada
4The University of Texas MD Anderson Cancer Center, Department of Carcinogenesis, Park Road 1, Smithville, Texas 78957, USA
*Present address: Department of Microbiology, The University of Tennessee, Knoxville, Tennessee 37996-0845, USA
**Addressee for correspondence. E-mail:

ABSTRACT: Using a highly specific radioimmunoassay, the sunlight-induced formation of cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts ([6-4] PPs) in viral DNA was investigated for natural virus communities in offshore and coastal waters of the western Gulf of Mexico as well as for clonal viral isolates. Concentrations of (6-4) PPs were consistently lower than CPD concentrations, and ranged from 1.5 to 17.0% of total measured photodamage. The accumulation of photoproducts varied among the natural viral community, the marine Vibrio phage PWH3a-P1 and the Synechococcus sp. DC2 (WH7803) cyanophage SYN-M3, which were deployed in situ from dawn until dark. Natural viral communities were more resistant to DNA damage than the cyanophage isolate SYN-M3, which was more resistant to damage than bacteriophage PWH3a-P1. Moreover, depth profiles revealed that photodamage in viral isolates deployed in the water column accumulated more rapidly at offshore stations than at coastal stations. In natural virus communities collected from offshore surface waters, photodamage accumulated during the solar day with maximum damage occurring between 15:00 and 18:00 h. Depth profiles obtained during calm seas showed that photodamage concentrations were high in surface waters at the offshore stations and at 1 coastal station. Results at other coastal stations undergoing significant mixing demonstrated no photoproduct accumulations. Results demonstrate that natural virus communities were more tolerant to DNA damaging radiation than the laboratory isolates used in this study. Consequently, laboratory isolates can be poor proxies for UV impacts on natural viral communities.

KEY WORDS: Marine viruses · UV · Pyrimidine dimers · 6-4 Photoproducts · DNA damage

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