Alterations of DNA-histone Interactions Following Irradiation

Summary The thermal denaturation profiles and melting temperatures (Tm) of DNA isolated from the thymus of rats which had received whole-body x-irradiation (1000 R) were found not to differ significantly from those of control animals. From this, it was concluded that the irradiation of animal systems does not principally involve damage to the double-stranded character of the DNA. Irradiation injury to DNA results more likely from depolymerization. The Tm values of both isolated and reconstituted deoxyribonucleoprotein (DNP) were found to decrease after irradiation. The lowered Tm values indicated alterations in the DNP which was attributed to damage involving the histones. Injury to the histones was shown also by gel electrophoresis.