Measurement of Co-60-gamma ray-induced DNA damage by capillary electrophoresis

Capillary electrophoresis was employed in this study to monitor Co-60-gamma ray-induced damage to a 1 kb DNA ladder which consists of restriction fragments ranging from 75 to 12 000 bp. DNA samples (0.5 mg/ml) were exposed to 0-60 Gy of gamma-radiation in the presence and absence of 110 mu mol/l ethidium bromide (EB). The analysis showed peak broadening without significant changes in the size distribution of irradiated fragments. Radiation-induced conformational changes may account for this peak broadening. EB addition caused small increases in the retention times of DNA fragments without affecting the overall DNA damage. This indicates that the presence of intercalated EB during radiation will not stabilize the DNA against Co-60-gamma ray-induced damage.