title: DNA strand breaking and rejoining in response to ultraviolet light in normal human and xeroderma pigmentosum cells.
abstract: We describe a reproducible technique for measuring DNA strand breaking and rejoining in cells after treatment with U.V.-light. Results obtained with normal human cells, xeroderma pigmentosum cells (XP, complementation group A) and XP variant cells suggest that all three of these cell-types can carry out single-strand incision with equal rapidity. However, the breaks so induced appeared to be only slowly rejoined in the XP variant cells and rejoined not at all in XP complementation group A cells. Furthermore, parental strand rejoining was inhibited by caffeine in XP variant cells but not in normal cells.
mesh_terms: D002110:Caffeine / Q000494:pharmacology; D002460:Cell Line; D004260:DNA Repair / Q000187:drug effects; D004277:DNA, Single-Stranded / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics*
chemical_list: D004277:DNA, Single-Stranded; D002110:Caffeine