Meeting Abstract
Neuropeptides are evolutionarily ancient, short polypeptide hormones that are expressed in the nervous and neuroendocrine systems of animals. Shared across Bilateria (e.g. insects and worms) and its sister group Cnidaria (e.g. jellyfishes and corals) are the Wamide and RFamide families of neuropeptides that appear to mediate a range of biological processes from motor behavior, reproduction, and development. In particular, it has been proposed that Wamides ancestrally controlled life cycle transitions from a free-swimming larva into a benthic (juvenile) form, because Wamides are sufficient to initiate life cycle transitions across cnidarians and annelid bilaterians. However, evidence for the necessity of Wamide signaling for such transitions is limited. By using CRISPR-Cas9-mediated reverse genetics, here we show that deeply conserved neuropeptides are not required for metamorphosis in the sea anemone cnidarian Nematostella vectensis. Transcripts of the cnidarian Wamide and RFamide—referred to as GLWamide and Antho-RFamide, respectively—are expressed in ectodermal sensory cells of a free-swimming planula larva; in addition, GLWamide transcripts, but not Antho-RFamide transcripts, occur in a subset of endodermal cells in the planula. However, null mutant planulae for either GLWamide or Antho-RFamide transform normally into primary polyps with oral tentacles. These results demonstrate that GLWamide and Antho-RFamide neuropeptidergic input from the planula larval nervous system is dispensable for the transition from a planula larva into a polyp in sea anemones, lending little support to the hypothesis that the key ancestral function of neuropeptides was to regulate life cycle transitions.
