Fig. 4

Positive correlation of sex-specific H3K27ac modifications on autosomal genes with the sex-biased gene expression. A The female-specific H3K27ac-associated genes are expressed higher in females. B The male-specific H3K27ac-associated genes are expressed higher in males. A total of 516 and 996 genes were identified to exclusively adjacent to the female- and male-specific H3K27ac peaks, respectively. The overall expression levels of the 516 genes are significantly higher in females than in males, while the overall expression of the 996 genes are significantly higher in males than in females. Kolmogorov Smirnov test was performed to compare the overall gene expression levels. **p < 0.01, ***p < 0.001. C Integrative Genomics Viewer (IGV) examples of H3K27ac binding and mRNA expression profiles of the selected autosomal genes showing sex-biased chromatin acetylation and gene expression. Note the AvBD12 and Fbln5 genes showed higher H3K27ac signal at the proximal regulatory regions and elevated mRNA expression levels in female gonads, whereas Tox3 and Nell2 genes showed higher H3K27ac signal at the neighboring regulatory chromatin regions and elevated mRNA expression levels in male gonads. The H3K27ac track represents the peak signal after subtracting the non-specific input. D The binding motif enrichment analysis of H3K27ac marked chromatin regions from different gonads. Note the binding motifs of the male-specific (Sox9) and female-specific (Foxl2) transcription factors were enriched in the H3K27ac marked chromatin regions in both sexes, although Sox9 and Foxl2 already show male- and female-biased expression, respectively