title: Studies on sister chromatid exchange (SCE) induction by gamma-irradiation and protective effect of L-cysteine in HeLa cells.
abstract: Effect of different doses of gamma-irradiation on SCE induction in unifiliarly 5-bromo 2-deoxyuridine substituted DNA was studied in various phases of cell cycle. Changes in gamma-irradiation induced SCE frequency was measured by post-irradiation treatment with antimutagen L-cysteine. Perturbation in cellular proliferation kinetics due to gamma-irradiation and gamma-irradiation plus L-cysteine was also studied. It was observed that gamma-irradiation is an efficient inducer of SCE and is most effective in S phase. L-cysteine also causes SCE induction which is slightly higher than the spontaneous level of SCEs found in HeLa cells. However, post-irradiation addition of L-cysteine reduces SCE frequency in gamma-irradiated cultures and this reduction is maximum in G1 phase irradiated cells. gamma-irradiation delayed the mitosis considerably and this delay continued to increase with increasing doses. L-cysteine reduced the delay in cell cycle caused by gamma-irradiation.
mesh_terms: D003545:Cysteine / Q000494:pharmacology*; D006367:HeLa Cells / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D011831:Radiation Genetics; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D012854:Sister Chromatid Exchange / Q000187:drug effects / Q000528:radiation effects*
chemical_list: D011837:Radiation-Protective Agents; D003545:Cysteine