Meeting Abstract

P1.41  Sunday, Jan. 4  Evolution of germ layers: insight from early Wnt signaling in a cnidarian KUMBUREGAMA, S*; WIKRAMANAYAKE, A; University of Hawaii at Manoa; University of Miami shalika@bio.miami.edu

The animal-vegetal (AV) axis, a character seen in most bilaterian eggs is crucial for germ layer segregation and gastrulation. This axis most likely played an important role in evolution of pattern formation in animal embryos, but its evolutionary origins are unknown. We use cnidarians, a sister group to bilaterians, to gain insight into evolution of the AV axis. In Nematostella vectensis, the AV axis is specified by localization of the Wnt pathway regulator Dishevelled (Dsh) to the animal pole of unfertilized eggs. Dsh activates Wnt/catenin signaling segregating endoderm from ectoderm. Additionally, Dsh signaling in the Wnt/PCP pathway regulates morphogenesis during gastrulation in Nematostella. We will discuss mechanisms that localize Dsh protein to the animal pole and how this protein selectively regulates cell fate specification and morphogenesis in Nematostella. Our results support the hypothesis that Wnt signaling played a critical role in germ layer segregation and gastrulation during animal evolution.