Figure 4.

Effects of ground-based radiation on embryonic development. (A) To investigate the responses of mouse embryos to the accumulated low- doses of radiation, we irradiated 2-cell embryos with Cs-137 gamma at the doses of 0.1 mGy, 0.5 mGy and 2 mGy in ground-based experiments. (B) The percentage of 2-cell embryos that successfully developed to the blastocyst stage during in vitro cultivation with radiation exposure. Data are presented as the means ± SEM from four independent experiments. ^*P < 0.05; ^**P < 0.01; n.s., not significant (P > 0.05). (C) Representative fluorescence images of γH2AX in blastocysts that developed from 2-cell embryos with or without exposure to different doses of radiation for 64 h. Scale bars, 50 μm. (D) The level of genome-wide DNA methylation in blastocysts exposed to 0, 0.1, 0.5 and 2 mGy radiation. The results are shows as the means ± SEM. ^*P < 0.05; n.s., not significant (P < 0.05) (t-test). (E) The number of differentially methylated regions (DMRs) in each pair-wise comparison of groups are shown. Blue and red bars indicate the proportion of hypermethylated and hypomethylated DMRs.