Alterations of liver DNA after x-irradiation. Reassociation and hybridization with nuclear RNA

When RNA was extracted either from irradiated or unirradiated rat livers, no difference in its ability to hybridize with DNA was detectable. In contrast, the ability of DNA extracted from irradiated animals to hybridize with RNA was decreased, probably as a result of DNA fragmentation. Sedimentation of X-irradiated DNA on sucrose gradients separated a small (low molecular weight) from a large peak (high molecular weight.). The hybridization capacity for RNA of the large molecular weight DNA was similar to that of unirradiated DNA, but that of the small molecular weight DNA was reduced. After irradiation of the denatured DNA in vitro, the reassociation of DNA was inhibited, which suggested that DNA strands had lost part of their complementariness. (author)