Evaluation of genotoxicity of the acute gamma radiation on earthworm Eisenia fetida using single cell gel electrophoresis technique (Comet assay)

Earthworms (Eisenia fetida) most suitable biological indicators of radioactive pollution. Radiation-induced lesions in DNA can be considered to be molecular markers for early effects of ionizing radiation. Gamma radiation produces a wide spectrum of DNA. Some of these lesions, i.e., DNA strand breaks and alkali labile sites can be detected by the single-cell gel electrophoresis (SCGE) or comet assay by measuring the migration of DNA from immobilized nuclear DNA. E. fetida were exposed to different doses of gamma radiation, i.e., 1, 5, 10, 20, 30, 40 and 50 Gy, and comet assay was performed for all the doses along with control at 1, 3 and 5 h post irradiation to evaluate the genotoxicity of gamma radiation in this organism. The DNA damage was measured as percentage of comet tail DNA. A significant increase in DNA damage was observed in samples exposed to 5 Gy and above, and the increase in DNA damage was dose dependent i.e., DNA damage was increased with increased doses of radiation. The highest DNA damage was noticed at 1 h post irradiation and gradually decreased with time, i.e., at 3 and 5 h post irradiation. The present study reveals that gamma radiation induces DNA damage in E. fetida and the comet assay is a sensitive and rapid method for its detection to detect genotoxicity of gamma radiation. © 2015 Elsevier B.V

Effects of acute gamma radiation on the reproductive ability of the earthworm Eisenia fetida

Earthworms are the most suitable biological indicators of radioactive pollution because they are the parts of nutritional webs, and are present in relatively high numbers. Four months old Eisenia fetida were exposed to different doses of gamma radiation, namely 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 & 60 Gy to study the effects of radiation on different reproductive parameters. The number of cocoons laid and the hatchlings emerged were recorded for all the selected doses. There was no reduction in cocoon production, however; decreasing size and weight of the cocoons was observed from the samples exposed to 20 Gy and above doses. Significant reductions in the hatchlings were recorded in earthworms exposed to 10 Gy and above doses. The dose response curves for a percentage reduction in hatchlings were constructed. Exposure to radiation dose of 1 and 2 Gy did not show any reduction, however, there was ≈10%, ≈50% and ≈90% decrease in the hatchlings in samples exposed to 3, 15 and 45, 50, 55 and 60 Gy doses respectively. Delayed hatchability was also reported at al exposure level. Histology of irradiated earthworms revealed that the structural damage in the seminal vesicles was prominent at the exposed dose of 3 Gy onwards with complete degeneration on exposure to 60 Gy of gamma radiation

Does exposure of male Drosophila melanogaster to acute gamma radiation influence egg to adult development time and longevity of F1–F3 offspring?

Two- to three-day-old male Drosophila melanogaster flies were irradiated with 1, 2, 4, 6, 8, 10, 20, 25, 30, 40 and 50 Gy doses of gamma radiation. The longevity and rate of development were observed for three successive generations to assess the impact of irradiation. The mean lifespan of irradiated flies was significantly increased at 1, 2 and 8 Gy, while it was vice versa for high doses at 30, 40 and 50 Gy. Paternal irradiation had an impact on F1 generation, with significantly increased mean longevity at 2 (female), 4, 6, 8 and 10 and decreased mean longevity at 40 and 50 Gy (male and female). Significant increase in the longevity was observed in the F2 generation of the 8 (male and female) and 10 Gy (male) irradiated groups, while decreased longevity was observed in F2 female progeny at 40 Gy. In the case of F3 progeny of irradiated flies, longevity did not show significant difference with the control. Paternal exposure to radiation had a significant impact on the mean egg to adult developmental time of the F1 generation; it was shortened at 2 Gy and extended at 25, 30, 40 and 50 Gy compared to the control. Mean development time at 30, 40 and 50 Gy was significantly increased in the F2 generation, while there were no significant changes in the F3 generation. The present study concludes that the effect of acute gamma irradiation on longevity and “egg to adult” development time of D. melanogaster may persist to following generations