Identification and characterization of neurosensory structures in intact and regenerating sea urchins

Recent sequencing of the sea urchin genome has shown that sea urchins share more genes with humans than was previously anticipated including those involved in vision and hearing. Although genes involved in the formation of organs of the special senses have been identified, the actual organs that they form in the sea urchin have not been described. In fact, surprisingly little is known about the nervous system of echinoderms despite their close relationship to humans and their century‐old role as a model for development. Using a combination of immunocytochemistry and in situ hybridization we identified neural elements in the distal appendages of the sea urchin, the tube feet. We identified nerve tracts that end in the periphery of the tube foot disk in close relationship to periodically arrayed clusters of cilia. We also identified Pax6 expressing cells at the periphery of the tube foot disk in close association with nerve tracts identified by synaptotagmin and anti‐acetylated tubulin immunostaining. To further characterize these structures we are examining the expression of other neurosensory genes in intact tube feet and during tube foot regeneration. These studies will provide information concerning the nature and location of sea urchin sensory structures and the gene hierarchy involved in their formation. They will also contribute to our understanding of how sensory neurons evolve and diversify. Identification of the components of the genetic pathway that underlie sensory cell formation will be key to understanding genetic programs that can be manipulated to affect cellular identity in prospective therapeutic strategies for diseases and developmental defects involving human sensory structures. Grant Funding Source : None