Meeting Abstract
Ctenophores are predatory gelatinous zooplankton which swim by beating eight rows composed of fused cilia. The recent publication of two ctenophore genomes, Pleurobrachia bachei and Mnemiopsis leidyi, has brought to the forefront molecular evidence that suggests ctenophores branched off from other animals near the base of the metazoan. Genomic data also uncovered the unusual characteristics of the ctenophore P. bachei nervous system. The evidence available suggests that ctenophores use a single canonical neurotransmitter, glutamate, to control their complex predatory behavior. Ctenophores exhibit an expansion of ionotropic glutamate receptors (iGluRs) that have undergone various molecular modifications after gene duplication. Phylogenetic studies show that these receptors are not associated with the common clades of AMPA, Kainate, NMDA and other phyla’s iGluRs from other other phyla. These receptors exhibit variable expression in ctenophore adults and embryos. Limited data suggests that glutamate is functional in the animal. However it is unclear in which cells glutamate is signaling. We are continuing to use a molecular and genomics approaches to ask how ctenophores have evolved variability in their iGluRs. We have identified three conserved domains in the P. bachei iGluRs, but only one conserved motif among other animal phyla. We also explore expression patterns of these iGluRs within P. bachei with parallel Phalloidin and Antibody staining of tyrosylated tubulin immunofluorescence to aid in identification of iGluR expression patterns within the muscles and neurons of P. bachei. Our findings suggest that Ctenophores use iGluRs in both neurotransmission and signaling muscle fibers. This new data will contribute to understanding the evolution of animal nervous systems
