Changes in the supercoiled structure of nuclear DNA in rat and human peripheral blood lymphocytes after γ-irradiation

A study has been made of the superhelical conformation of nuclear DNA of peripheral blood lymphocytes of the rat after in vivo or in vitro γ-irradiation, and of man after in vitro irradiation. The changes caused were measured by sedimentation analysis and viscosimetry. It was shown that the supercoiled conformation of DNA of peripheral blood lymphocytes is actively repaired both in vitro and in vivo. This process has a multiphase character. The full restoration of superhelical DNA conformation takes place in vitro by five hours after irradiation and after total-body irradiation of rats only in 24 hours. (U.K.)