Investigations on supercoiled DNA in various rat cells.

The effect of radiation induced single-strand breaks in nuclear DNA and the repair of this damages on the sedimentation properties of nucleoids obtained from rat spleen, rat thymus and rat Yoshida tumour cells was studied. A dose dependent effect of ethidium bromide intercalation on the behaviour of supercoiled DNA could be demonstrated. The repair process of radiation induced single-strand breaks in the DNA of Yoshida tumour cells was delayed in the presence of prostaglandin E2 in the incubation medium. Additionally some in vivo repair experiments were carried out on cells of whole body irradiated rats.