Effect of ionizing radiation on DNA synthesis in ataxia telangiectasia cells

Abstract

The effect of ionizing radiation on DNA synthesis in control and ataxia telangiectasia (AT) lymphoblastoid cell lines was determined. A dose dependent decrease in DNA synthesis was observed in control cells, and the rate and extent of this decrease in synthesis increased with time after irradiation. No decrease in DNA synthesis was obtained in AT cells, imediately following irradiation, at doses up to 400 rads. At longer times postirradiation, inhibition of synthesis increased but the extent of inhibition was less in AT cells than controls at all doses used. An immediate depression of DNA synthesis was evident in control cells after a radiation dose of 200 rads reaching a maximun at 90 mm postirradiation. Little or no decrease in DNA synthesis was evident in AT cells up to 60 min after the same radiation dose, but a decrease occurred between 60 and 90 min after irradiation. The rate of recovery of DNA synthesis to normal levels was more rapid in AT cells than in controls.