Cytogenetic effects of ⁶⁰Co gamma radiation on Biomphalaria glabrata (Say, 1818) embryos

SUMMARY

Biomphalaria glabrata embryos irradiated with ⁶⁰Co gamma radiation at doses of 5, 10 and 15 Gy during the blastula stage were analyzed cytogenetically 24 hours after treatment. For embryos exposed to the 10 Gy dose, the chromosomal study was repeated 48 hours after irradiation. Several types of structural chromosome aberrations were detected, the most common being dicentrics and acentric fragments. Dicentric data fitted the linear model better, while the acentric fragments fitted the quadratic model. A significant decrease in the frequency of metaphases with aberrations was detected 48 hours after irradiation (12%) when compared with 24 hours (38.9%), indicating a probable elimination of cells with chromosome aberrations. The results also suggest a possible chromosome loss in cells irradiated with the 15 Gy dose, 24 hours after treatment. A fall in mitotic index with increasing radiation dose was observed, showing a certain parallelism between the frequency of chromosome aberrations and the degree of mitotic depression 24 hours after irradiation. An association of radioinduced chromosome aberrations with the morphogenetic effects of radiation is suggested to have occurred in embryos irradiated in the blastula phase.