Centre for Environmental Radioactivity (CERAD CoE), NMBU, 1433 Ås, Norway; Norwegian University of Life Sciences (NMBU), Faculty of Veterinary Medicine and Biosciences, P.O. Box 8146 Dep., 0033 Oslo, Norway.
Norwegian Institute for Water research (NIVA), Gaustadalléen 21, NO-0349, Oslo, Norway.
Ecotoxicol Environ Saf. 2018 Jun 15;154:19-26. doi: 10.1016/j.ecoenv.2018.02.031. Epub 2018 Feb 22.
The biological effects of gamma radiation may exert damage beyond that of the individual through its deleterious effects on reproductive function. Impaired reproductive performance can result in reduced population size over consecutive generations. In a continued effort to investigate reproductive and heritable effects of ionizing radiation, we recently demonstrated adverse effects and genomic instability in progeny of parents exposed to gamma radiation. In the present study, genotoxicity and effects on the reproduction following subchronic exposure during a gametogenesis cycle to Co gamma radiation (27 days, 8.7 and 53 mGy/h, total doses 5.2 and 31 Gy) were investigated in the adult wild-type zebrafish (Danio rerio). A significant reduction in embryo production was observed one month after exposure in the 53 mGy/h exposure group compared to control and 8.7 mGy/h. One year later, embryo production was significantly lower in the 53 mGy/h group compared only to control, with observed sterility, accompanied by a regression of reproductive organs in 100% of the fish 1.5 years after exposure. Histopathological examinations revealed no significant changes in the testis in the 8.7 mGy/h group, while in 62.5% of females exposed to this dose rate the oogenesis was found to be only at the early previtellogenic stage. The DNA damage determined in whole blood, 1.5 years after irradiation, using a high throughput Comet assay, was significantly higher in the exposed groups (1.2 and 3-fold increase in 8.7 and 53 mGy/h females respectively; 3-fold and 2-fold increase in 8.7 and 53 mGy/h males respectively) compared to controls. A significantly higher number of micronuclei (4-5%) was found in erythrocytes of both the 8.7 and 53 mGy/h fish compared to controls. This study shows that gamma radiation at a dose rate of ≥ 8.7 mGy/h during gametogenesis causes adverse reproductive effects and persistent genotoxicity (DNA damage and increased micronuclei) in adult zebrafish.
γ 射线的生物效应可能会通过其对生殖功能的有害影响而对个体造成损害之外的损害。生殖性能受损会导致连续几代的种群数量减少。为了继续研究电离辐射的生殖和遗传效应，我们最近证明了暴露于 γ 射线的父母的后代会受到不良影响和基因组不稳定性。在本研究中，在配子发生周期中连续 27 天以 8.7 和 53 mGy/h（总剂量 5.2 和 31 Gy）的 Co γ 辐射进行亚慢性暴露后，研究了成年野生型斑马鱼（Danio rerio）的遗传毒性和对生殖的影响。与对照组和 8.7 mGy/h 组相比，暴露于 53 mGy/h 组的胚胎产量在暴露一个月后显著降低。一年后，与对照组相比，仅在 53 mGy/h 组中胚胎产量显著降低，观察到不育症，并伴有 100%的鱼在暴露 1.5 年后生殖器官退化。组织病理学检查显示，在 8.7 mGy/h 组中睾丸没有明显变化，而在暴露于该剂量率的 62.5%的雌性中，发现卵母细胞仅处于早期卵黄前发生阶段。在照射 1.5 年后，使用高通量彗星分析测定全血中的 DNA 损伤，暴露组（8.7 和 53 mGy/h 雌性分别增加 1.2 和 3 倍；8.7 和 53 mGy/h 雄性分别增加 3 倍和 2 倍）显著高于对照组。与对照组相比，8.7 和 53 mGy/h 鱼的红细胞中发现的微核数（4-5%）显著增加。本研究表明，在配子发生期间，剂量率≥8.7 mGy/h 的 γ 射线会导致成年斑马鱼产生不良的生殖效应和持续的遗传毒性（DNA 损伤和增加的微核）。
