Figure 3.

Hierarchical clustering to identify early accumulating proteins. Three clusters were selected from hierarchical clustering results. A (red cluster) and B (orange cluster) look very similar with up-regulated proteins at an early stage (2 hours after irradiation) but are statistically different. The red cluster contains 5 spots already detected by the statistic method implemented in the ImageMaster software (indicated with diff). The third one C (green cluster) gathers proteins up-regulated from 4 hours and beyond. The dendogram on the left indicates the order of the protein grouping. The intensities (protein accumulation) range from bright green (underproduced in comparison with the mean value) to bright red (overproduced in comparison with the mean value) according to the color scale at the bottom of the figure. The three successive columns for each biological sample correspond to the corresponding 3 technical replicates recorded and they are numbered in the bottom of the figure. Red and orange clusters are statistically different partly because of (i) missing values and (ii) inability of the statistical method available in the software program to analyze gel images (here, ImageMaster 2D) to detect these spots in some gels.