title: Effect of protein diet on age-dependent methylation of liver nuclear components of mice administered N-nitrosodimethylamine.
abstract: Protein diets deficient or enriched in DL-methionine were studied for the effect of methylation of nuclear components in subadult and adult outbred albino male mice given N-nitrosodimethylamine. After the mice were fed diets for 6 days, they were given ip injections of [14C]N-nitrosodimethylamine (5 mg/kg body wt) and killed 45 minutes later. Liver nuclei were isolated; incorporation of 14C into nuclear proteins and methylation of DNA and RNA were determined. In the subadult and adult animals the nuclear protein content was diminished by shortage of a single essential amino acid. Incorporation of 14C into the total protein was reduced. The reduction amounted to 55% in the subadult and 23% in the adult animals. Neither an age-dependent nor a diet-dependent change in the specific methylation of DNA and RNA was observed. Analysis of methylation of DNA and RNA was observed. Analysis of methylated purine bases showed an age-related rise in O6-methylguanine in the adult as compared with the subadult mice.
mesh_terms: D000375:Aging; D000818:Animals; D002250:Carbon Radioisotopes; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004044:Dietary Proteins / Q000494:pharmacology*; D004128:Dimethylnitrosamine / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D008745:Methylation; D051379:Mice; D009698:Nucleoproteins / Q000378:metabolism; D012313:RNA / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D004044:Dietary Proteins; D009698:Nucleoproteins; D012313:RNA; D004247:DNA; D004128:Dimethylnitrosamine