Extracellular DNA level in the blood of irradiated rats.

There is high-molecular DNA in the blood of unirradiated rats which moves as a single fraction during electrophoresis in 0.5% agarose. At short times (2-5 h) after gamma-irradiation at doses from 1 to 100 Gy a low-molecular species of DNA appears (about 180 nucleotide pairs), the amount of which is directly proportional to exposure dose at 5 h after exposure. It has been established by Southern hybridization that the low-molecular DNA has few nucleotide sequences common with those of the high-molecular DNA, but it shows homologously to genomic sequences.