Enrichment of brain-related genes on the mammalian X chromosome is ancient and predates the divergence of synapsid and sauropsid lineages
2009 (English)In: Chromosome Research, ISSN 0967-3849, E-ISSN 1573-6849, Vol. 17, no 6, 811-820 p.Article in journal (Refereed) Published
Previous studies have revealed an enrichment of reproduction- and brain-related genes on the human X chromosome. In the present study, we investigated the evolutionary history that underlies this functional specialization. To do so, we analyzed the orthologous building blocks of the mammalian X chromosome in the chicken genome. We used Affymetrix chicken genome microarrays to determine tissue-selective gene expression in several tissues of the chicken, including testis and brain. Subsequently, chromosomal distribution of genes with tissue-selective expression was determined. These analyzes provided several new findings. Firstly, they showed that chicken chromosomes orthologous to the mammalian X chromosome exhibited an increased concentration of genes expressed selectively in brain. More specifically, the highest concentration of brain-selectively expressed genes was found on chicken chromosome GGA12, which shows orthology to the X chromosomal regions with the highest enrichment of non-syndromic X-linked mental retardation (MRX) genes. Secondly, and in contrast to the first finding, no enrichment of testis-selective genes could be detected on these chicken chromosomes. These findings indicate that the accumulation of brain-related genes on the prospective mammalian X chromosome antedates the divergence of sauropsid and synapsid lineages 315 million years ago, whereas the accumulation of testis-related genes on the mammalian X chromosome is more recent and due to adaptational changes.
Place, publisher, year, edition, pages
2009. Vol. 17, no 6, 811-820 p.
Chromosome evolution, Vertebrate sex chromosomes, Gene expression, Gene enrichment
IdentifiersURN: urn:nbn:se:uu:diva-112613DOI: 10.1007/s10577-009-9072-8ISI: 000270648100011PubMedID: 19731051OAI: oai:DiVA.org:uu-112613DiVA: diva2:292014