The distribution of 7-methylguanine in the families of repetitive and unique sequences of rat liver chromatin DNA has been studied using the technique of DNA-DNA reassociation. Rats were injected with di[14C]methylnitrosamine and chromatin DNA was prepared 3 h later. The distribution of 7-methylguanine was found to be random between these classes of DNA. We have also studied chromatin DNA from rats treated with unlabelled DMN plus [3H]thymidine in this way, in order to find if DMN affects DNA synthesis within any one kinetic class. Our results suggest that there is no difference in the extent of synthesis between these classes.
Animals Base Sequence