Meeting Abstract
Similarity of Metazoan mechano-sensory cells as well as sponge choanocytes has has led to inferences that such cells evolved from a common ancestral cell type. Usher syndrome (US) causes deafness and blindness in vertebrates, and the suite of genes characteristic of this syndrome are known to play key roles in mechanosensation. To explore the ancestry of function of these genes in the base of the metazoa we conducted a bioinformatic assessment across basal Metazoa and Eukarya. Having confirmed a variety of these genes through the base of the Metazoa we are conducting antibody work to examine the expression of US genes in Aurelia, a medusa bearing cnidarian sister to the better studied Bilaterian clade. Aurelia is one of the more basal taxa with discrete sensory structures including a statocyst associated with mechanoreceptors, cnidocyte sensory response and eyes. Hair cells project tightly packed ascending rows of microvillar “stereocilia” tip-linked to each other and to a cilium using the US1 subset of US genes. In Aurelia, immunofluorescence detected an association of the US1 gene Myosin VIIa in mechanosensory cells, associated with cnidocytes, known to be tip-linked in other Cnidaria. This strongly supports the common functional origin of mechanoreceptors through the base of the cnidarian Bilaterian clade. We hope to examine this general problem in greater detail across the sensory cell types found in Aurelia. More broadly biomedical syndromes provide a nexus of interaction that is potentially of substantial interest in an evolutionary context.
