Meeting Abstract

99.2  Sunday, Jan. 6  Expression of Wnt pathway genes in Ectopleura larynx (Hydrozoa: Aplanulata) and implications for their potential role in hydrozoan life cycle evolution NAWROCKI, A.M.*; CARTWRIGHT, P.; Pomona College, Claremont, CA; University of Kansas, Lawrence, KS annarocky@gmail.com

The canonical Wnt signaling pathway is conserved in its role in axial patterning throughout Metazoa. In hydrozoans (Phylum Cnidaria), Wnt signaling is implicated in oral-aboral patterning of the planula, polyp and medusa. Here, we present gene expression data for Wnt pathway components in the hydrozoan species Ectopleura larynx. Using next-generation sequencing, we isolated genes from the canonical Wnt signaling pathway and examined their expression in E. larynx. Unlike most hydrozoans, E. larynx lacks a larva and the polyp instead develops directly from a brooded embryo. These embryos develop within gonophores that represent a truncated medusa stage of the hydrozoan life cycle, with gonophores of E. larynx retaining evolutionary remnants of medusae, including tentacles. Our data are consistent with the Wnt pathway being involved in axial patterning of both the polyp and elements of the truncated medusa. Specifically, changes in the spatial expression of Wnt pathway genes are correlated with the development of different oral structures in male and female gonophores. The absence of expression of components of the Wnt pathway, and presence of a Wnt pathway antagonist in the developing anterior end of the gonophore, suggest that downregulation of the Wnt pathway may be implicated in the evolution of medusa reduction in Hydrozoa.