Meeting Abstract

99.1  Monday, Jan. 6 13:30  Posterior axis elongation without segmentation: insights into the origins of the bilaterian trunk FRITZENWANKER, J.H.*; LOWE, C.J.; Hopkins Marine Station of Stanford University jhfritzenwanker@web.de

One common feature of bilaterian animals is their anteroposterior (AP) axis which is divided into two major regions; the head and the trunk. In many groups the posterior trunk elongates by a process of posterior growth characterized by a posterior, terminal growth zone from which tissue is added. However, due to sparse comparative data, it is not clear how mechanisms of trunk development arose at the base of the bilaterians. All functional studies of posterior axis elongation to date in bilaterians have been conducted in either chordates or arthropods, which are characterized by a segmented body plan where mechanisms of segmentation are tightly coupled with posterior growth. This makes it challenging to untangle the two processes experimentally. We have begun to study posterior axis elongation during the development of the unsegmented hemichordate Saccoglossus kowalevskii to determine what components of the posterior growth/segmentation-network, shared between chordates and arthropods, is associated with posterior growth in this novel developmental system. We are exploring these mechanisms by characterizing the gene regulatory networks regulating posterior patterning during trunk development.