DNA-REPAIR IS LESS EFFICIENT IN THE NUCLEAR MATRIX THAN IN NON-MATRIXNUCLEAR FRACTIONS IN THE LIVER OF RATS TREATED WITH 2-AMINOFLUORENE

The amount of DNA adducts and radioactive thymidine incorporation into DNA fractions attached and not attached to the nuclear matrix in the liver of rats treated with the carcinogen 2-aminofluorene (2-AF) were compared. The rate of [H-3]thymidine incorporation was directly propor tional to the amount of adducts in total hepatic DNA. Within the first 10 h after the carcinogen treatment, the level of adducts in the nucl ear matrix DNA was higher than in the whole nuclei. The rate of [H-3]t hymidine incorporation into the nuclear matrix DNA was 5-30% lower tha n into DNA in whole nuclei at any time after 2-AF injection. We sugges t that in rat liver cells, the 2-AF-induced DNA repair does not occur in close contact with the nuclear matrix.