Radiation induced DNA damage evaluation of insects using comet assay

Ionizing radiation is a potent inducer of DNA damage because it causes single-and double-stranded breaks at alkali-labile sites, base damage, and cross links. to evaluate the level of genetic damage in insects, 5^th instar caterpillars of Papilio polytes (Lepidoptera) and 5^th instar nymphs Dysdercus cingulatus (hemiptera) were irradiated with 10 gy, 30 gy, 40 gy, 50 gy and 70 gy gamma rays. Single-cell gel electrophoresis was employed for detecting DNA strand breaks and measuring the extent of DNA lesion and also to measure the repair kinetics in single cell. the results showed that tail length and tail moment were seen to be increased exponentially. the average tail length and tail moment of irradiated P. polytes cells varied from 6.33 ±0.33 to 318.00 ± 0.58 and 0.36 ± 0.07 to 180.38 ± 2.79 respectively as the radiation dosage increased from 10 gy to 70 gy. Similarly, the average tail length and tail moment of D. cingulatus increased exponentially from 3.33 ± 0.33 to 374.67 ± 2.33 and 0.16 ± 0.04 to 305.32 ± 1.45 respectively. these studies showed that the genetic defects of ionizing radiation on insects increased exponentially as the radiation dosage increases and depends on the rate at which it is delivered. The present study confirmed the applicability of the comet assay as a sensitive tool for the detection of DNA lesions caused by extremely high radiation dose, which is not possible by using standard cytogenetic methods.