[Study of populations of nuclear RNA of rat liver cells after short-term exposure to a carcinogen].

RNA-DNA hybridization in a solution with DNA excess was employed. Rat's livers were given one injection of 4-dimethylaminoazobenzene, and, when compared 24 hours afterwards with livers from normal untreated rats, demonstrated an altered transcription. The hybridization capacity of the nuclear RNA isolated from carcinogen-treated livers is lower than that of the control RNA. The changes observed in the carcinogen treated RNA population may be due to changes in the rate of transcription in DNA sites.