The Evolutionary and Functional Genomics of Dosage Compensation in Drosophila

描述（由申请方提供）：剂量补偿是一种性别中X连锁基因表达改变的过程，以平衡异配子性别中X染色体和常染色体数量的差异。非重组Y染色体的变性是性染色体进化的一个普遍方面。使雄性中X连锁基因的表达水平相等的选择压力伴随Y染色体变性，从而驱动剂量补偿的进化。果蝇米兰达-一个物种，我们最近产生了从头基因组序列组装-有三个不同年龄的性染色体，并在不同阶段的过渡，从普通的常染色体到异形性染色体。具体地说，X-L是果蝇属的祖先性染色体，年龄> 60 MY，X-R由D. pseudobscura亚群和> 10 MY年龄，而其新性染色体（约1 MY年龄）仍然在很大程度上类似于常染色体，但新X正在进化部分剂量补偿。D.因此，米兰达提供了一个独特的系统，使用比较和功能基因组学方法来研究作用中剂量补偿的演变。我们将使用ChIP-seq技术与全基因组群体分析一起，在功能上表征剂量补偿复合物对X染色体的靶向作用，以及它如何演变。

DESCRIPTION (provided by applicant): Dosage compensation is the process by which the expression of X-linked genes is altered in one sex to counterbalance the difference in X-chromosome and autosome number in the heterogametic sex. Degeneration of the non-recombining Y chromosome is a general facet of sex chromosome evolution. Selective pressure to equalize expression levels of X- linked genes in males accompanies Y-chromosome degeneration, thus driving the evolution of dosage compensation. Drosophila miranda - a species for which we recently generated a de novo genome sequence assembly - has three sex chromosomes of different age and at different stages of transition from ordinary autosomes into heteromorphic sex chromosomes. Specifically, X-L is the ancestral sex chromosome of the genus Drosophila and >60MY old, X-R is shared by members of the D. pseudoobscura subgroup and >10MY old, while its neo-sex chromosome (about 1MY old) still largely resembles an autosome, but the neo-X is evolving partial dosage compensation. D. miranda therefore provides a unique system to study the evolution of dosage compensation in action using a comparative and functional genomics approach. We will use ChIP-seq techniques together with whole-genome population analysis to functionally characterize the targeting of the dosage compensation complex to the X chromosome, and how it evolves.