"Gene Trafficking on an Evolving X Chromosome in Drosophila"

基因在基因组中是非随机分布的。从全基因组表达谱中出现的一个有趣的模式是，具有性别偏倚表达的基因，即在两性之间表达差异的基因，在性染色体上表现出偏倚分布。特别是，果蝇X染色体上的雄性偏向基因被耗尽，因此X染色体已经失去了男性特征。男性偏倚基因的缺失可以部分解释为男性基因从X染色体上移走。这些模式背后的进化力量是有争议的，可能涉及雄性生殖系X失活、性拮抗或剂量补偿机制。我们最近为米兰达果蝇（Drosophila miranda）生成了一个全新的基因组序列组装，它有一个新形成的性染色体系统。它的新y染色体正处于从普通常染色体向简并y染色体的转变过程中。因此，新X正在进化出分化X的典型特性，包括获得部分剂量补偿，以及——正如初步数据所表明的——源自其新X的过量基因易位。因此，米兰达博士提供了一个独特的系统来研究进化中的X染色体上的基因运输机制及其进化原因，使用比较和功能基因组学方法。

Genes are distributed non-randomly across the genome. One intriguing pattern to emerge from genome-wide expression profiling is that genes with sex-biased expression that is, genes that are differentially expressed between the sexes show a biased distribution on sex chromosomes. In particular, male-biased genes are depleted from the Drosophila X chromosome, such that the X has become demasculinized. The deficiency of male-biased genes can partly be explained by movement of male genes off the X chromosome. The evolutionary forces underlying these patterns are controversial and may involve male germline X inactivation, sexual antagonism, or dosage compensation mechanisms. Drosophila miranda - a species for which we recently generated a de novo genome sequence assembly - has a newly formed sex chromosome system. Its neo-Y chromosome is in transition from an ordinary autosome to a degenerate Y. In response, the neo-X is evolving the stereotypical properties of a differentiated X, including the acquisition of partial dosage compensation and - as suggested by preliminary data - an excess of gene translocations originating from its neo-X. D. Miranda therefore provides a unique system to study the mechanisms of gene trafficking on an evolving X chromosome and its evolutionary causes in action using a comparative and functional genomics approach.