Figure 7.

Focus counting analysis in mouse tongue basal cells. Mice were irradiated with doses 0.5, 1.0, 1.5, 2, 3, 4 and 5 Gy (3 or 6 mice for each dose). Panel A: each data point represents average number of foci per nucleus calculated for an individual fluorescence image. The number of nuclei identified in each image varies from 50 to 160. The total number of images analysed is 105. The line is drawn with the intercept = 0 and the slope = 1. The correlation coefficient R² = 0.886 (P<0.0001). Panel B: each data point represents average number of foci per nucleus calculated in a range of fluorescence images obtained from mouse tongue sections irradiated at a given dose. Error bars indicate the standard error. The line is generated as a result of linear regression analysis. Two-parameter linear regression analysis resulted in the following values: slope = 0.990 ± 0.042, intercept = 0.124 ± 0.308. Given that the intercept is not different significantly from 0, subsequent single-parameter linear regression resulted in the following value: slope = 1.004 ± 0.021. The correlation coefficient R² = 0.989 (P<0.0001). Panel C: Dose response of γ-H2AX foci induction in mouse tongue basal cells 1 hr after irradiation. Symbols represent results of manual counting (circles), automatic counting (triangles) and automatic 3D counting (squares). Lines show results of non-linear regression analysis using the three-parameter saturation model as described in the Figure 6 legend; solid line for manual and automatic 2D counting, dashed line for automatic 3D counting. The yield of foci for automatic 2D counting δ = 3.05 ± 0.63 Gy⁻¹, for manual counting δ = 3.16 ± 0.42 Gy⁻¹, for automatic 3D counting δ = 4.26 ± 1.20 Gy⁻¹. For manual and automatic 2D counting, the regression analysis reveals some deviation from the linear response with N_m = ~30.