INVESTIGATION OF THE REPAIR OF SINGLE-STRAND BREAKS IN HUMAN DNA USING ALKALINE GEL-ELECTROPHORESIS

Unstimulated lymphocytes from eight healthy persons were exposed to 10-, 30-, and 100-Gy doses of 60Co γ radiation. The repair of damaged DNA was measured by (1) alkaline gel electrophoresis (extracted DNA loaded on 0.25% agarose gel, run at 1 V/cm for 39-44 h) at 0, 1, and 2 h after exposure and (2) incorporation of [3H]thymidine into unstimulated lymphocytes in the presence of 2 mM hydroxyurea 1 and 2 h after exposure. Both methods - alkaline gel electrophoresis and thymidine incorporation - showed that repair was completed within 2 h.