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

在节肢动物中，同源节段可以有非常不同的形态。一个特别不同的部分是头部部分，它形成了三脑，因此被称为三脑部分。根据节肢动物分支的不同，这一部分携带不同的附肢--甲壳类动物的第二触角或海龟类的足掌--或者已经失去了它的附肢--昆虫和多足动物的中间部分。然而，这种丧失在系统发生上是独立的，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，三脑节段代表表达HOX基因的最前面的节段，这通常负责节段的指定。在iBeetle基因组范围的RNAi筛选中，我们想要分离一组与红粉甲虫的中间片段发育有关的基因，以了解指定这一片段的遗传电路。此外，我们希望以这些信息为参照点，就导致不同节肢动物分支内三脑节段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.