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Direct effects of UV-B radiation on the freshwater heterotrophic nanoflagellate Paraphysomonas sp.

ABSTRACT: The formation of DNA photoproducts in organisms exposed to ambient levels of UV-B radiation can lead to death and/or reduced population growth in aquatic systems. Dependence on photoenzymatic repair to reverse DNA damage caused by UV-B radiation is demonstrated for Paraphysomonas sp., a member of a widely distributed genus of heterotrophic nanoflagellates. At 20 degrees C, Paraphysomonas sp. was exposed to a range of UV-B intensities encountered in natural systems. Populations of the flagellate survived and grew in a dose-dependent manner, but only when simultaneously exposed to photorepair radiation (PRR). In contrast, flagellates exposed to UV-B at 15 degrees C suffered 100% mortality except at the lowest UV-B level (with PRR) tested, which suggested a photorepair temperature optimum above 15 degrees C. After acute UV-B exposures, DNA damage (measured as the formation of pyrimidine dimers) was reduced only in organisms that underwent subsequent exposure to PRR. Populations kept in the dark after UV-B exposure maintained the initial levels of pyrimidine dimers. These results are the first to demonstrate the reliance of a heterotrophic flagellate on photoenzymatic DNA repair for survival from UV-B exposure.

SUBMITTER: Macaluso AL

PROVIDER: S-EPMC2704802 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Direct effects of UV-B radiation on the freshwater heterotrophic nanoflagellate Paraphysomonas sp.

Macaluso Amy L AL Mitchell David L DL Sanders Robert W RW

Applied and environmental microbiology 20090508 13

The formation of DNA photoproducts in organisms exposed to ambient levels of UV-B radiation can lead to death and/or reduced population growth in aquatic systems. Dependence on photoenzymatic repair to reverse DNA damage caused by UV-B radiation is demonstrated for Paraphysomonas sp., a member of a widely distributed genus of heterotrophic nanoflagellates. At 20 degrees C, Paraphysomonas sp. was exposed to a range of UV-B intensities encountered in natural systems. Populations of the flagellate ...[more]

PMID: 19429560

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Direct effects of UV-B radiation on the freshwater heterotrophic nanoflagellate Paraphysomonas sp.

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Direct effects of UV-B radiation on the freshwater heterotrophic nanoflagellate Paraphysomonas sp.

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