Meeting Abstract

P2.41  Jan. 5  Development of neuromuscular system in the scyphozoan Aurelia sp.1 from the polyp to ephyra larval stage NAKANISHI, N*; YUAN, D; HARTENSTEIN, V; JACOBS, D K; UCLA nnakanis@ucla.edu

According to the current view of metazoan phylogeny, the presence of neuromuscular systems is a derived character shared by cnidarians and bilaterians. Detailed understanding of the development of the neuromuscular system in cnidarians is thus essential to shed light on its origin and evolution. The scyphozoan Aurelia medusa is known to possess two functionally independent nervous systems, the diffuse nerve net (DNN) and the giant fiber nerve net (GFNN). The DNN has a net-like structure over exumbrella and subumbrella and is responsible for feeding and spasm behaviors. The GFNN runs parallel with radial muscles and is responsible for the swimming behavior. Here, in an attempt to better understand the development of these two distinct nervous systems and their spatial relationship with the muscular system in the scyphozoan Aurelia, immunohistochemistry with anti-FMRFamide and anti-tyrosine tubulin antibodies and fluorescent phalloidin were used to visualize the development of the neuromuscular system of Aurelia sp.1 from the sedentary polyp through free-swimming ephyra larval stage. Immunoreactivity with the anti-FMRFamide antibody showed a net-like distribution, resembling the DNN. On the other hand, a strong immunoreactivity with the anti-tyrosine tubulin antibody occurred along the radial muscle fiber in the ephyra larva, indicating its localization in the GFNN. Phalloidin illuminates the filamentous actin abundant in muscle fibers. Thus, these markers can effectively visualize distinct sets of the neuromuscular system of Aurelia sp.1. By using confocal microscopy, structural changes in the neuromuscular system associated with the metamorphosis from the polyp into ephyra larva will be examined.