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. Author manuscript; available in PMC: 2012 Sep 16.
Published in final edited form as: Cell. 2011 Sep 16;146(6):1016–1028. doi: 10.1016/j.cell.2011.08.008

Figure 6.

Figure 6

Correlation of histone Kcr with gene expression in meiotic, post-meiotic male germ cells, and in tissues. (A) Hyper-crotonylation wave in elongating spermatids. Kcr was detected on paraffin mouse testis tubule sections representing different stages of spermatogenesis by immunohistochemistry (IH) using an anti-Kcr antibody. Pre-meiotic spermatogonia (Spg) and meiotic spermatocytes (Spc) cells are present at the periphery and middle of the tubule sections, whereas post-meiotic round (RS), elongating (ES) and condensing (CS) spermatids are near the lumen. The nuclei of ES are positive for Kcr. (B, C) Genes associated with higher Kcr in RS than Spc are mostly post-meiotically activated and show a predominant expression in the testis. The genes associated with Kcr peaks were divided into three categories according to their Kcr levels in Spc and RS: i) Spc=RS, similar Kcr levels between Spc and RS; ii) Spc>RS, lower Kcr levels in RS than Spc (fold change >=2); iii) Spc<RS, higher Kcr levels in RS than Spc (fold change >=2). The expression of these genes in male germ cells (B) and tissues (C) was then compared among the three categories. (B) Expression in male germ cells. Left panel: respective proportions of genes (Y axis) with higher expression either in Spc or RS among the three gene categories (X axis). Right panel: heatmap showing the expression of the third category of genes (Kcr, Spc <RS) in Spc (4 samples) and in RS (4 samples). Color scale showing low expression in green to high expression in red. (C) Expression of genes in tissues. Left panel: pie charts showing the respective proportions of genes with the highest level of expression in the indicated. Genes with the highest tissue-specific expression are those whose levels of expression, in the indicated tissue, are elevated by at least two standard deviations above the mean expression in all tissues. Right panel: heatmap showing the expression of the third category of genes in the indicated tissues. (D) The X-linked genes are highly and specifically marked by histone Kcr in RS. The respective proportion (%) of genes associated with Kcr (left panel) or Kac peaks (right panel) among chromosomes in male germ cells is shown.