The Roles of Segmentation Gene Homologues in Annelids

[00:90378]目前对动物细胞分化和模式形成的理解在很大程度上是基于从“模型”系统获得的数据，如果蝇黑腹果蝇。目前尚不清楚苍蝇的发育机制在其他门中保存的程度。这个问题将通过检查环节动物中苍蝇发育调节基因的同源物及其在身体结构多样化中的作用来解决。在迄今为止所研究的所有动物中，Hox基因簇负责确定沿身体前后轴的区域身份。该基因簇的上游调控指向身体形态差异的潜在来源。除了果蝇之外，关于Hox基因调控的知识是有限的。因此，我们的具体目标是在环节动物中鉴定出与苍蝇同源的调控Hox基因表达的基因。在水蛭和多毛类中，与两个果蝇片段基因（驼背和尾端）的同源物将被表征。这种比较方法将使我们能够区分一般发育机制和门特异性机制，从而为环节动物胚胎的形成和区域规范提供新的见解。

0090378SavageCurrent understandings of cell differentiation and pattern formation in animals have largely been based on data obtained from 'model' systems such as the fruit fly Drosophila melanogastor. The extent to which developmental mechanisms operating in the fly are conserved in other phyla is at present unknown. This question will be addressed by examining annelid homologues of fly developmental regulatory genes and their role in the diversification of body plans. In all animals that have been studied to date, the Hox gene cluster is responsible for determining regional identity along the anterior-posterior body axis. The upstream regulation of this gene cluster points to a potential source of morphological variation between body plans. Knowledge of Hox gene regulation beyond Drosophila is limited. Therefore, the specific aim is to identify in annelids homologues to fly genes which have been shown to regulate Hox gene expression. The homologues to two Drosophila segmentation genes, hunchback and caudal , in both leeches and in polychaetes will be characterized. This comparative approach will allow us to differentiate between general developmental mechanisms and phylum-specific ones, in so doing providing novel insights into the formation and regional specification of the annelid embryo.