title: Detection in situ of gamma-ray-induced DNA strand breaks in single cells: enzymatic labelling of free 3'-OH ends.
abstract: We report a procedure allowing the detection and counting of free 3'-OH DNA strand extremities in single cells in situ. Terminal transferase (TdT) catalysed the incorporation of 3H-dGMP into fixed nuclei of human colonic adenocarcinoma cells (HT29), using free 3'-OH ends as initiator. Radioactivity was detected by autoradiography and determined quantitatively with a rapid image-processing system for grain counting. The initiator activity for TdT increases with the dose of gamma-rays in the dose range 2.5-20 Gy.
mesh_terms: D000230:Adenocarcinoma; D001345:Autoradiography; D002460:Cell Line; D002588:Cesium Radioisotopes; D003110:Colonic Neoplasms; D004253:DNA Nucleotidylexotransferase; D004273:DNA, Neoplasm / Q000528:radiation effects*; D003848:Deoxyguanine Nucleotides / Q000096:biosynthesis; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans
chemical_list: D002588:Cesium Radioisotopes; D004273:DNA, Neoplasm; D003848:Deoxyguanine Nucleotides; C007257:2'-deoxyguanosine 5'-phosphate; D004253:DNA Nucleotidylexotransferase