title: O6-alkylguanine and structural modifications in liver DNA of dialkylnitrosamine-treated rats.
abstract: Isolated rat liver DNA was fractionated on benzoylated-naphthoylated-DEAE-cellulose (BND-cellulose) columns. In experiments with dimethyl-nitrosamine (DMN)-treated (1-30 mg/kg) rats killed 24 h after injection, the amount of DNA eluting in the formamide fraction (i.e., containing single-stranded or partially denatured regions) was increased in a dose-dependent way. The absence of an effect at 6 days after DMN indicated that above regions disappear much more rapidly from rat liver DNA than do those DMN-induced lesions that give rise to more persistent DNA fragmentation in alkaline sucrose gradients. This indicates that 2 different lesions are involved. When the extents of alkylation at the O6- and 7-position of guanine in the NaCl-eluted and formamide-eluted DNA were compared, no significant differences were observed. Our results indicate that, at least in the present system, neither the presence nor the repair of O6-alkylguanine is related to the formation of single-stranded regions in rat liver DNA.
mesh_terms: D000818:Animals; D004247:DNA; D004260:DNA Repair; D004277:DNA, Single-Stranded; D004128:Dimethylnitrosamine; D004305:Dose-Response Relationship, Drug; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives*; D008099:Liver / Q000187:drug effects*; D009602:Nitrosamines; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004277:DNA, Single-Stranded; D009602:Nitrosamines; D006147:Guanine; C008450:7-methylguanine; D004247:DNA; C008449:O-(6)-methylguanine; D004128:Dimethylnitrosamine