Effects of 3'-methyl-4-dimethylaminoazobenzene on RNA processing in rat liver nuclei

Treatment of rats with the hepatocarcinogen 3'-methyl-4-dimethylaminoazobenzene (3'MeDAB) leads to the accumulation of polyadenylated RNA in rat liver nuclei. This polyadenylated nuclear RNA contains more double-stranded stretches than polyadenylated nuclear RNA isolated from liver of control animals. Treatment with 3'MeDAB also results in an increase of sequences homologous to small chromatin-associated RNA (fr 3-RNA) in the polyadenylated nuclear RNA and in the appearance of these sequences in polyadenylated nuclear RNA which contains some double-stranded stretches. The last mentioned fraction of nuclear RNA from liver of control animals did not hybridize with a DNA probe for fr 3-RNA. It is proposed that, perhaps as a result of inhibition of RNA processing by 3'MeDAB, the transient stages of RNA processing can be observed in animals treated with this compound.