Meeting Abstract

P1.55  Jan. 4  An investigation into the cell adhesion molecules present in sponge tissue ROSSIN, M.*; SAWYER, S. J; Southern Illinois University; Southern Illinois University sasawye@siue.edu

Poriferans are currently classified as the phylogenetic sister group to the Metazoa. One reason for this separation is the lack of evidence for formation of germ layers during sponge development. Germ layers are the initial tissue layers that appear during embryogenesis and play pivotal roles in adult development. Animals such as Cnidarians and Ctenophores form two germ layers, the endoderm and the ectoderm; all other Metazoa are triploblastic, also forming mesoderm. Gastrulation, the coordinated movement of cells to form embryonic germ layers, has been compared to the formation of choanocyte chambers in sponges; others argue choanocyte chamber formation does not truly constitute gastrulation. As germ layers lead to the formation of adult tissues, without gastrulation forming germ layers, sponges are not thought to form true tissues including organized epithelia layers; however, sponges appear to have number genes that encode the necessary components of organized epithelia tissue. Genes for alpha- and beta-integrins, protocadherins, alpha-actinin and beta-catenin have all been sequenced from the sponge Oscarella carmela. We are using immunohistochemistry on three different species of sponges to investigate the localization of integrins and beta-catenin in sponge tissue to determine if these molecules are orientated in sponge tissue as they would be in true epithelial tissue. We seek to determine if sponges are using adhesion molecules known to regulate epithelial integrity in a manner similar to other animals.