An evolutionary consequence of dosage compensation on Drosophila melanogaster female X-chromatin structure?
Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD 20892-8028 USA
BMC Genomics 2010, 11:6 doi:10.1186/1471-2164-11-6Published: 5 January 2010
X chromosomes are subject to dosage compensation in Drosophila males. Dosage compensation requires cis sequence features of the X chromosome that are present in both sexes by definition and trans acting factors that target chromatin modifying machinery to the X specifically in males. The evolution of this system could result in neutral X chromatin changes that will be apparent in females.
We find that the general chromatin structure of female X chromosomes is distinct from autosomes. Additionally, specific histone marks associated with dosage compensation and active chromatin marks on the male X chromosome are also enriched on the X chromosomes of females, albeit to a lesser degree.
Our data indicate that X chromatin structure is fundamentally different from autosome structure in both sexes. We suggest that the differences between the X chromosomes and autosomes in females are a consequence of mechanisms that have evolved to ensure sufficient X chromosome expression in the soma of males.