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. Author manuscript; available in PMC: 2011 Jan 1.
Published in final edited form as: Nature. 2010 Jul 11;466(7306):612–616. doi: 10.1038/nature09172

Figure 3. Convergent gene gain on the chicken Z and human X chromosomes.

Figure 3

a. Gene density of Z and X chromosomes compared to autosomes. Both are unusually gene poor, with about half the gene density of a typical autosome.

b. Venn diagrams comparing gene content of chicken Z and human X chromosomes to orthologous autosomes. Most genes on orthologous autosomes remain on the sex chromosomes; few have been lost. Both chicken Z and human X gained hundreds of genes not present on orthologous autosomes.

c. Percentage of protein coding genes with testis ESTs in Unigene. Left panel: Compared to chicken autosomes, Z chromosome is enriched for testis-expressed genes. Single-copy Z chromosome genes (SC) show no enrichment for testis ESTs compared to autosomal gene, but nearly all multi-copy (MC) genes are expressed in testis. Right panel: Similar results on human X chromosome.