Chromosomal aberrations induced by 12C6+ ions and 60Co γ-rays in mouse immature oocytes

The ovaries of Kun-Ming strain mice (3 weeks) were irradiated with different doses of 12C6+ ion or 60Co γ-ray. Chromosomal aberrations were analyzed in metaphase II oocytes at 7 weeks after irradiation. The relative biological effectiveness (RBE) of 12C6+ ion was calculated with respect to 60Co γ-ray for the induction of chromosomal aberrations. The 12C6+ ion and 60Co γ-ray dose–response relationships for chromosomal aberrations were plotted by linear quadratic models. The data showed that there was a dose-related increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values for 12C6+ ions relative to 60Co γ-rays were 2.49, 2.29, 1.57, 1.42 or 1.32 for the doses of 0.5, 1.0, 2.0, 4.0 or 6.0 Gy, respectively. Moreover, a different distribution of the various types of aberrations has been found for 12C6+ ion and 60Co γ-ray irradiations. The dose–response relationships for 12C6+ ion and 60Co γ-ray exhibited positive correlations. The results from the present study may be helpful for assessing genetic damage following exposure of immature oocytes to ionizing radiation.