Meeting Abstract

P1.42  Tuesday, Jan. 4  Rhogocytes of the giant keyhole limpet, Megathura crenulata MARTIN, Alanna M.*; MARTIN, Gary G.; TSAI, Whitney L. E.; BUTLER, Robert; Occidental College, Los Angeles; Occidental College, Los Angeles; Occidental College, Los Angeles; Cal Tech, Pasadena gmartin@oxy.edu

Rhogocytes are cells scattered throughout the connective tissue of gastropods that are thought to be involved with the production of the respiratory pigment hemocyanin (HCN). Using TEM, rhogocytes in several species of gastropods have been found with dilated cisternae of RER containing aggregates of HCN but it is not clear whether rhogocytes are synthesizing or recycling HCN. Markl and Harris (2000) localized the mRNA for HCN in rhogocytes of the abalone but not the giant keyhole limpet M. crenulata. In M. crenulata, the HCN forms a large aggregate (didecamer) called keyhole limpet hemocyanin (KLH). KLH is highly antigenic in vertebrates and used as an adjuvant in the treatment of cancers and allergic responses. In this study we characterize the rhogocytes of M. crenulata. Rhogocytes are common in the connective tissue surrounding the esophagus and intestine, occur in pockets within the digestive gland and are in low density in the mantle and foot. The cells are surrounded by a 62nm thick basal lamina. Regions of the plasma membrane are folded to form parallel longitudinal grooves connected by diaphragms. The most obvious structures in rhogocytes are large lysosomal vacuoles that take up neutral red and Lysotracker dye. Samples processed throughout the year show rhogocytes with dilated cisternae of RER filled with molecules resembling KLH and these areas stain with antibodies for KLH. Finally we have been able to extract mRNA for KLH from rhogocytes showing that rhogocytes in the giant keyhole limpet as in other gastropods are the source of KLH. Other functions of these cells, involving the large lysosomes, require further work and our initial attempts to culture these cells will be presented.