Fig. 7. Chromatin accessibility after allelic Firre deletions and a Firre/Dxz4 deletion.

a Density histograms of the distribution of allelic proportions (spretus/(spretus + BL6)) of ATAC peaks along the autosomes and the X chromosomes for WT (blue) and ΔFirre^Xa (red). No shift is observed (Wilcoxon test: −log10P = 32). b. Percentages of ATAC peaks along the autosomes and the X chromosomes classified as spretus-specific, BL6-specific, or both show no differences between WT (blue) and ΔFirre^Xa (red). c. Plots of Xi-associated (common +Xi-specific) ATAC peak density (counts binned within 500 kb windows) along the Xi show increased accessibility at the telomeric end of the Xi in ΔFirre^Xa (red) versus WT (blue). To account for differences in the number of SNP-covered peaks between samples due to sequencing depth, the binned counts are scaled by a factor obtained from the between-sample ratios of autosomal diploid SNP-covered peaks. d Density histograms of the distribution of allelic proportions (spretus/(spretus + BL6)) of ATAC peaks show a shift to a lower Xa/(Xa + Xi) ratio in the double-mutant ΔFirre^Xi/ΔDxz4^Xi (purple), compared to ΔDxz4^Xi (black) and ΔFirre^Xi (green), consistent with increased accessibility on the Xi (Wilcoxon test: −log10P = 35). e Percentages of ATAC peaks in ΔDxz4^Xi (black), ΔFirre^Xi (green), and ΔFirre^Xi/ΔDxz4^Xi (purple) along the autosomes and the X chromosomes classified as spretus-specific, BL6-specific, or both show an increase on the BL6 Xi in the double mutant.