Effect of ionizing radiation on synthesis of sub-replicon size DNA in ataxia telangiectasia cells

The effect of γ-radiation on the synthesis of short fragments of DNA was studied in control and ataxia telangiectasia lymphoblastoid cell lines. Cells were pulsed with [H]thymidine for 90 sec, which resulted in labelling of DNA fragments ranging from 0.1 to 2.1 x 10 daltons in size in both control and ataxia telangiectasia cells. After exposure to 800 rad of γ-rays, a decrease in the formation of DNA over this molecular weight range was observed in four control cell lines, 30 min post-irradiation. Four ataxia telangiectasia cell lines however exhibited no reduction in the synthesis of sub-replicon size DNA