title: The stability of methylated purines and of methylphosphotriesters in the DNA of V79 cells after treatment with N-methyl-N-nitrosourea.
abstract: V79-379A cells growing in suspension culture were treated with N-methyl-N-nitrosourea at concentrations of 0.6 and 1.2 mM. After incubation for periods from 1 to 48 h DNA was isolated from the cells and the concentrations of 7-methylguanine, O6-methylguanine, 3-methyladenine and methyl phosphotriesters were determined. After correction for dilution resulting from DNA synthesis during the incubation it was found that no loss of O6-methylguanine or methylphosphotriesters occurred; 7-methylguanine disappeared with a half-life of 22 h and 3-methyladenine was detectable only immediately after the initial treatment. The results show that these cells eliminate 7-methylguanine and 3-methyladenine from DNA by a repair process but are unable to excise or repair O6-methylguanine or methyl phosphotriesters.
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000032:analysis; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000032:analysis*; D004260:DNA Repair / Q000187:drug effects*; D004952:Esters / Q000032:analysis; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis; D008770:Methylnitrosourea / Q000494:pharmacology*; D009607:Nitrosourea Compounds / Q000494:pharmacology*; D011687:Purines / Q000032:analysis*
chemical_list: D004952:Esters; D009607:Nitrosourea Compounds; D011687:Purines; D006147:Guanine; D008770:Methylnitrosourea; D004247:DNA; D000225:Adenine