Gene expression in mouse, dog, and human spermatocytes and round spermatids. A) Left and middle: boxplots showing median, 25, and 75 percentile log2(FPKM + 2) values of the mRNA levels of genes on chromosomes 1,3, and X in dog and mouse (using the dataset published by ) spermatocytes (spc) and round spermatids (st). Genes that were expressed below the 25 percentile values of the whole genome average in both spermatocytes and spermatids were excluded from this analysis. Right: boxplot showing median, 25, and 75 percentile values of the mRNA levels represented as log2(expression value). The values were obtained from published microarray hybridization data using mRNA isolated from human spermatocytes and spermatids , and shown here for chromosomes 1,3, and X. Genes with very low expression (value <100, Affimetrix probesets with mean signal intensities <100) in both spermatocytes and spermatids were excluded from this analysis. Asterisks indicate significant difference in gene expression between autosomes and the X chromosome for spermatocytes and spermatids. Plus indicates significantly higher X-linked than autosomal gene expression in spermatids. Horizontal red lines indicate significant difference in X-linked gene expression between spermatocytes and spermatids. B) Differentially expressed genes along chromosome 1 and chromosome X, comparing expression in spermatocytes and round spermatids from the dog. Genes that are significantly up-regulated in round spermatids compared to spermatocytes (differentially expressed genes; DEG) are indicated as +1 bars, and significantly down-regulated genes are represented as −1 bars along chromosome X and chromosome 1. In addition, the log2(FPKM + 2) values of all genes along the chromosomes in spermatocytes and round spermatids are shown. Gene density along the chromosomes can be inferred from the density of the bar representing locations of Ensembl annotated genes along the chromosome shown at the bottom. For the X chromosome, the approximate location of the PAR border is indicated by a light blue line, and centromere location is indicated by a dashed gray line.