P2.61 Thursday, Jan. 5 Expression of myoregulatory factors in the sea urchin Lytechinus variegatus FLORES, E.B.*; BYRUM, C.A.; University of Miami; College of Charleston email@example.com
Although much has been learned about the molecular interactions that regulate early formation of endomesoderm in the sea urchin embryo, much less is known about the mechanisms regulating the specification and differentiation of endodermal and mesodermal cells that form later in development. Our research focuses on the processes responsible for formation of one subgroup of late mesoderm; muscle. The phylogenetic position of our subject, the echinoderm Lytechinus variegatus, makes it an attractive model for studying the evolution of muscle formation in metazoans. As a basal deuterostome, L. variegatus provides a valuable intermediate between the vertebrate phyla and more pleisiomorphic groups such as the Cnidaria. Using reverse transcriptase PCR and wholemount in situ hybridization, we have evaluated the expression of several genes known to participate in the regulation of myogenesis or in the differentiation of muscle in numerous metazoan groups. Embryos cultured at 22˚C were evaluated every two hours from the late mesenchyme blastula stage (16 hours postfertilization) to the late pluteus stage (46 hours postfertilization at 22˚C). This preliminary work provides an important foundation for future functional studies in the formation of muscle in basal deuterostomes.