Irradiation induces a loss of H3K9me3 that mainly affects the recent L1Md subfamilies. (A and B) MA-plots showing nonsignificant (blue dots) and significant (P < 0.05, pink dots) differential H3K9me3 enrichment at confident peaks between NIR and IR conditions analyzed both in U and M-MRA (A) and TE loci (B). The number of peaks showing a significant decreased (down) or increased (up) in H3K9me3 enrichment upon IR is indicated in the plot. (C) Distribution of the percent of each family of TE among the total TE loci in the mouse mm10 genome (up) and among the significantly differentially enriched TE (bottom) retrieved in B. (D) Violin plot representing the distribution of H3K9me3 concentration at each locus retrieved in B for LINE, LTR, SINE, and DNA families of TEs in NIR and IR conditions. (E) Violin plot representing the distribution of the log₂ fold change (FC) in H3K9me3 concentration at each locus retrieved in B for LINE and LTR. (F) Correlation plot representing H3K9me3 concentration quantified at all LINE elements in M-MRA vs. their age in million years (My). R, Pearson correlation coefficient. (G) Violin plot representing the distribution of the log₂ fold change in H3K9me3 concentration at each locus retrieved in B for L1Md or other LINE. (H) Plot profile of H3K9me3 enrichment along the L1Md sequences (>5 kb) ± 1 kb flanking regions in IR (green) vs. NIR (blue) conditions. Wilcoxon test. (I) H3K9me3 enrichment at L1Md promoters analyzed by ChIP-qPCR normalized to H3K9me3 enrichment at repetitive 5S rRNA. n = 3 independent experiments. Each dot represents pools of three (NIR) or four (IR) mice. Results are expressed as fold change from the mean value of the NIR condition and represented as means ± SEM. t test. *, P < 0.05; **, P < 0.01; ****, P < 0.0001.