The molecular mechanisms of DNA repair following chronic medium-dose-rate (MDR) γ-ray-induced damage remain largely unknown.
We used a cell function imager to quantitatively measure the fluorescence intensity of γ-H2A.X foci in MDR (0.015 Gy/h and 0.06 Gy/h) or high-dose-rate (HDR) (54 Gy/h) γ-ray irradiated embryonic fibroblasts derived from DNA-dependent protein kinase mutated mice (scid/scid mouse embryonic fibroblasts (scid/scid MEFs)). The… CONTINUE READING
Figure 2. Increased intensity of c-H2A.X foci induced by HDR c-ray irradiation in wild-type MEFs. A. Histogram of cell cycle fractionation in wild-type MEFs, with G1 and G2/M phases indicated by black bars. B. Relation between averaged I/A (fluorescence intensity of c-H2A.X foci per nuclear area) and total doses (0, 0.54, 1.08, 1.67, 2.16, and 3.24 Gy) by HDR irradiation in the G1-phase fraction of wild-type MEFs. Each point in the figure indicates a relative ratio (IR/non-IR: averaged I/A in the irradiated condition/averaged I/A in the non-irradiated condition), which is the representative value for each irradiation condition. This result indicates that the averaged I/A is increased dose-dependently by HDR irradiation. C. Relation between averaged I/A (c-H2A.X foci per nuclear area) and total doses (0, 0.54, 1.08, 1.67, 2.16, and 3.24 Gy) by HDR irradiations in the G2/Mphase fraction of wild-type MEFs. Each averaged I/A was calculated from 10 replicate experiments (2 independent experiments with 5 points taken in each experiment) for detecting relative ratios. doi:10.1371/journal.pone.0045320.g002