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 Jan 5;11:6. doi: 10.1186/1471-2164-11-6.
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.
X 染色体在雄性果蝇中受到剂量补偿。剂量补偿需要 X 染色体的顺式序列特征，这些特征在两性中都存在，还需要反式作用因子将染色质修饰机制靶向到雄性的 X 染色体上。该系统的进化可能导致中性 X 染色质变化，在雌性中是显而易见的。
我们发现雌性 X 染色体的一般染色质结构与常染色体明显不同。此外，与剂量补偿相关的特定组蛋白标记和雄性 X 染色体上的活性染色质标记也在雌性 X 染色体上富集，尽管程度较低。
我们的数据表明，X 染色体的染色质结构在两性中都与常染色体的结构有根本的不同。我们认为，雌性 X 染色体与常染色体之间的差异是为了确保雄性体细胞中有足够的 X 染色体表达而进化出的机制的结果。
