EXCISION REPAIR OF UVR-INDUCED PYRIMIDINE DIMERS IN CORNEAL DNA |
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Authors: | Steven E. Freeman Lee A. Applegate Ronald D. Ley |
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Affiliation: | Photocarcinogenesis Program, Division of Biomedical Research, Lovelace Medical Foundation, 2425 Ridgecrest Drive, S.E., Albuquerque, NM 87108, USA |
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Abstract: | Abstract— We measured excision repair of ultraviolet radiation (UVR)-induced pyrimidine dimers in DNA of the corneal epithelium of the marsupial, Monodelphis domestica , using damage-specific nucleases from Micrococcus luteus in conjunction with agarose gel electrophoresis. We observed that 100 J -2 of UVR from aFS–40 sunlamp(280–400 nm) induced an average of 2.2 ± 0.2 times 10-2 endonuclease-sensitive sites per kilobase (ESS/kb) (pyrimidine dimers) and that ∼ 50% of the dimers were repaired within 12 h after exposure. We also determined that an exposure of 400 J m-2 was needed to induce comparable numbers of pyrimidine dimers (2.5 times 10-2) in the DNA of skin of M. domestica in vivo . In addition, we found that 50% of the dimers were also removed from the epidermal cells of M. domestica within 12 h after exposure. A dose of 100 J m-2 was necessary to induce similar levels of pyrimidine dimers (2.0 ± 0.2 times 10-2) in the DNA of the cultured marsupial cell line Pt K2 ( Potorous tridactylus ). |
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