KOENIG, MM; SAWYER, SJ*; Southern Illinois University, Edwardsville; Southern Illinois University, Edwardsville: The architecture of the actin microfilament network in various species of sea anemones

Tissue integrity is maintained through interactions between the cytoskeleton and cell adhesion molecules. Cnidarians were the first animals to have true tissues, but the morphology of the cytoskeleton and its relation to cell adhesion molecules is not well characterized in these animals. Previously we have shown the arrangement of the actin microfilaments (MFs) in the symbiotic sea anemone, Aiptasia pulchella. In this anemone, the most intense staining of MFs occurs in the basal processes of the epithelial-muscular cells of the endoderm. Interestingly, other than the basal processes, there is poor MF staining in the endoderm of both symbiotic and aposymbiotic A. pulchella. There is a well-developed MF network in the ectoderm in these anemones. To determine if a poorly developed MF network is characteristic of all Actinaria, we are investigating the morphology of the MFs in several species of sea anemones. MF staining in the sea anemone Metridium senile is similar to that of A. pulchella except that in M. senile MFs can be visualized throughout the endoderm, although the MF staining in the endoderm is reduced compared to the ectoderm. We also show that the MFs of A. pulchella are resistant to disruption by 10 µM cytochalasin B. The susceptibility of the MFs of M. senile to disruption by cytochalasin B is being tested. Understanding the cytoskeletal architecture of these cnidarians will aid in our understanding of how these animals maintain tissue integrity during environmental stress.