Global upregulation of X-linked genes in Hr6b knockout spermatocytes. A) Number of differentially expressed genes per chromosome. Significantly expressed genes were annotated and plotted per chromosome. Except for chromosome 7 and chromosome X, the number of downregulated genes in the Hr6b knockout is higher than in wild type spermatids. A reverse effect is observed for chromosome X, where the number of upregulated genes in knockout round spermatids is higher than in wild type. Green, downregulated in knockout. Red, upregulated in knockout. B, C) The expression profile along chromosome X (B) and 3 (C) in wild type and Hr6b knockout spermatocytes and round spermatids. Gene expression data (linear scale) were mapped to the genomic location of each gene (Affymetrix annotation). D) Average expression per chromosome. RMA normalized average expression for each chromosome was calculated and plotted. Average expression, linear scale, is plotted on the y-axis, and chromosome numbers are shown on the x-axis. The late spermatocytes showed very few and variable changes in average gene expression per chromosome. For round spermatids, the average expression on all chromosomes is slightly higher in wild type, except on chromosome 7 and chromosome X. On chromosome 7 the average expression is equal in wild type and knockout round spermatids. On chromosome X, the average expression is significantly higher in knockout round spermatids. Abbreviations: wt, spt, round spermatid wild type; ko spt, round spermatid Hr6b knockout; wt spc, spermatocyte wild type; ko spc, spermatocyte Hr6b knockout.