Rejoining Kinetics of DNA Single- and Double-Strand Breaks in Normal and DNA Ligase-Deficient Cells after Exposure to Ultraviolet C and Gamma Radiation: An Evaluation of Ligating Activities Involved in Different DNA Repair Processes

摘要: The repair kinetics for rejoining of DNA single- and double-strand breaks after exposure to UVC or gamma radiation was measured in cells with deficiencies ligase activities their normal counterparts. Human 46BR were deficient I. Hamster EM9 EM-C11 III activity as a consequence mutations the XRCC1 gene. XR-1 had mutation XRCC4 gene, whose product stimulates IV activity. assessed by comet assay alkaline conditions technique graded-field gel electrophoresis neutral conditions, respectively. cells, which are known re-ligate at reduced rate single-strand incurred during processing damage induced but not radiation, shown have radiation-induced breaks. exhibited ionizing reported previously, well radiation. radiation-induced-DNA but, contrast demonstrated same parental cell line resealing resulting from Both displayed significant defect confirmed be highly appeared rejoin irradiation rates close normal. Taken together these results indicate that: (1) I is involved only nucleotide excision repair; (2) plays an important role breaks; (3) implicated base breaks, probably repair.