Meeting Abstract
Understanding how new neuropeptides become functionally integrated into the pre-existing nervous system during evolution is important for understanding the mechanism by which neural function evolves. In Cnidaria, novel neuropeptides known as RPamides likely emerged in the sea anemone lineage, but little is known about their function. To bridge this fundamental knowledge gap, we examine the expression pattern of RPamides during development of the sea anemone Nematostella vectensis. We show that RPamide precursor transcripts first occur during gastrulation in scattered epithelial cells in the aboral ectoderm. These RPamide-positive epithelial cells then extend basal neuronal processes toward the aboral pole, forming an aboral sensory nerve net of the planula larva. During planula development, several RPamide-positive sensory cells become part of the aboral apical organ, and a subset of endodermal sensory cells begin to express RPamides. During metamorphosis into a polyp, RPamide-positive sensory cells in the aboral ectoderm disappear via apoptosis, and RPamide-positive ectodermal sensory cells develop in growing oral tentacles. These expression data strongly suggest a role of RPamide in sea anemone development and/or larval behavior. Interestingly, the developmental expression pattern of RPamide differs from those of RFamide and GLWamide – ancient families of neuropeptides thought to have been present in the last common ancestor of Cnidaria and Bilateria – indicative of distinct functions. Thus, during cnidarian evolution, RPamides may have acquired new function that pre-existing neuropeptides did not have; alternatively, RPamides may have inherited old function that pre-existing neuropeptides subsequently lost. We are currently taking a CRISPR-Cas9-mediated gene knockout approach to directly test RPamide function during N. vectensis development.
