Changes in template properties of chromatin during aminoazo-carcinogenesis

Male rats were kept on a diet containing the carcinogen 3′-methyl-4-dimethylaminoazobenzene. No difference from the control was found either in the electrophoretic spectrum of the total protein of deoxyribonucleoproteins (DNP) or nonhistone proteins, or in the character of the melting curves of DNA and DNP, or in the template ability of DNA isolated from rat liver. DNP of tumor tissue functioned more actively as template for RNA synthesisin vitro in a system with animal or bacterial RNA-polymerase, with low concentrations of substrates (of the order of 2·10−5 M), but RNA synthesis did not differ from the control in the presence of high concentrations of each of the substrates (2·10−3 M). During lysis of the nuclei in a solution with alkaline pH the percentage of activity of RNA-polymerase that could be extracted from the complex with chromatin decreased considerably if the rats were fed with the carcinogen.