Revealing a genetic circuitry governing the development of the tritocerebral head segment

在节肢动物中，同源节段可以具有相当不同的形态。一个特别多样的节段是产生三头脑的头节，因此被称为三头脑节。根据节肢动物的不同，这个节段携带着不同的附属物——甲壳类动物的第二触角或螯足类动物的须肢——或者已经失去了附属物——昆虫和多足类动物的瓣间节。然而，这种损失与系统发育无关，在这两种情况下，都可能是对陆地生活的适应。此外，在所有真节肢动物中，三头脑节段是表达Hox基因的最前端节段，通常负责节段规范。在iBeetle全基因组RNAi筛选中，我们想要分离出一组全面的基因，这些基因参与了红粉甲虫（Tribolium castaneum）食膜间隙发育，以了解指定该片段的遗传电路。此外，我们希望利用这些信息作为参考点，对导致不同节肢动物中三脑节多样化和趋同进化的进化变化提出功能性问题。

In arthropods, homologous segments can have quite diverse morphologies. One particularly diverse segment is the head segment that gives rise to the tritocerebrum and has therefore been termed the tritocerebral segment. Depending on the arthropod clade, this segment carries diverse appendages - second-antenna in crustaceans or pedipalps in chelicerates - or has lost its appendages - intercalary segment of insects and myriapods. The loss, however, is phylogenetically independent and in both cases probably an adaptation to life on land. Moreover, the tritocerebral segment represents in all euarthropods the anterior-most segment expressing a Hox gene, which is usually responsible for segment specification. Within the iBeetle genome-wide RNAi screen we want to isolate a comprehensive set of genes involved in intercalary segment development of the red flour beetle Tribolium castaneum to understand the genetic circuitry specifying this segment. Moreover, we want to use this information then as reference point to ask functional questions on the evolutionary changes that led to the diversification and convergent evolution of the tritocerebral segment within the diverse arthropod clades.