Evaluation of gamma radiation-induced DNA damage in Aedes aegypti using the comet assay.

The study was undertaken to evaluate gamma radiation-induced DNA damage in Aedes aegypti. The comet assay was employed to demonstrate the extent of DNA damage produced in adult male A. aegypti exposed to seven different doses of gamma radiation, ranging from 1 Gy to 50 Gy. DNA damage was measured as the percentage of comet tail DNA. A significant linear increase in DNA damage was observed in all samples; the extent of damage being proportional to the dose of gamma radiation the organism received, except in those treated with 1 Gy. The highest amount of DNA damage was noticed at 1 h postirradiation, which decreased gradually with time, that is, at 3, 6 and 12 h postirradiation. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the postirradiation time increased. The comet assay serves as a sensitive and rapid technique to detect gamma radiation-induced DNA damage in A. aegypti. This could be used as a potential biomarker for environmental risk assessment.

Effect of gamma radiation on life history traits of Aedes aegypti (L.).

Aedes aegypti is an important vector for Dengue and Dengue hemorrhagic fever. Considering its medical importance and its relevance as a model system, this study was undertaken to evaluate the impact of different doses of gamma radiation for three generations of A. aegypti. Two to three days old virgin males of A. aegypti were irradiated with 15 doses of gamma radiation, ranging from 1 to 50 Gy and were immediately mass mated with the same aged virgin females. Observations were made for changes on their life history traits, particularly fecundity, hatchability, adult emergence, sex ratio and longevity, for three generations. Adult males exposed 30, 35, 40, 45 and 50 Gy doses showed a significant decrease in fecundity in F0 generations. While hatchability was observed to have decreased with increasing radiation doses from 3 Gy onwards in the F1 generation, samples irradiated with 30, 35, 40, 45 and 50 Gy maintained significant decline in hatchability in their succeeding generations, F2 and F3 also. Similarly, a decline was observed in adult emergence from 3 Gy onwards in all three generations. A male favoring sex ratio distortion was observed at the doses of 35, 40, 45 and 50 Gy in all three generations. Following exposure to 4 Gy, parental males and the resultant progeny showed increased longevity by 10.56 and 8.66 days respectively. Similarly, the F1 generations of samples irradiated with 30, 35 and 40 Gy exhibited an increase in longevity by 7.16, 7.44 and 6.64 days respectively. Dose response curve for fertility among the three generations was drawn and presented. The effect of radiological exposure on the life history traits of A. aegypti varies with dose for the three generations studied. These results have potential implications in mutational studies and risk assessment and also contribute to a better understanding towards employment of the sterile insect technique in A. aegypti, plausibly paving the way to an effective mosquito genetic control program.