title: Relative induction of cyclobutane dimers and cytosine photohydrates in DNA irradiated in vitro and in vivo with ultraviolet-C and ultraviolet-B light.
abstract: SV40 DNA was irradiated in vitro and in vivo with UV-C (240-280 nm) and UV-B (280-320 nm) light, and damaged sites sensitive to digestion with Escherichia coli endonuclease III (endo III) and bacteriophage T4 endonuclease V (endo V) were quantified. The frequency of endo III-sensitive sites (primarily cytosine photohydrates) induced was 1-2% of the frequency of endo V-sensitive sites (cyclobutane dimers) in both purified SV40 DNA and intracellular episomal SV40 DNA. Endo III- and endo V-sensitive sites in DNA were induced in the same relative proportion at both UV-C and UV-B wavelengths. We found no evidence to support earlier inferences that intracellular conditions enhance the formation of cytosine photohydrates or other monobasic forms of DNA damage.
authors.affiliation: University of Texas M.D. Anderson Cancer Center, Science Park/Research Division, Smithville 78957.
authors.forename: D L
authors.initials: DL
authors.lastname: Mitchell
authors.forename: J
authors.initials: J
authors.lastname: Jen
authors.forename: J E
authors.initials: JE
authors.lastname: Cleaver
mesh_terms: D001483:Base Sequence; D002461:Cell Line, Transformed; D003503:Cyclobutanes / Q000528:radiation effects*; D003596:Cytosine / Q000528:radiation effects*; D004279:DNA, Viral / Q000528:radiation effects*; D015263:Deoxyribonucleases, Type III Site-Specific / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010957:Plasmids / Q000528:radiation effects; D013539:Simian virus 40 / Q000528:radiation effects*; D012996:Solutions / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014867:Water / Q000528:radiation effects
chemical_list: D003503:Cyclobutanes; D004279:DNA, Viral; D012996:Solutions; D014867:Water; D003596:Cytosine; D015263:Deoxyribonucleases, Type III Site-Specific