Meeting Abstract
P3.175 Tuesday, Jan. 6 Mucilage Antigenicity and Composition in Different Zooxanthella Strains MAZZILLO, Maria J.*; KEMPF, Stephen C.; Auburn University; Auburn University mazzimj@auburn.edu
Zooxanthellae (genus: Symbiodinium) are brown, unicellular algae that reside intracellularly in most cnidarians and comprise at least 8 clades, each consisting of several strains. In this mutualism the endosymbiotic algae are within a symbiosome membrane (host and symbiont-derived) and donate photosynthetic products to their host in exchange for shelter and nutrients. Symbiodinium produce mucilage that surrounds the cells while within the symbiosome or as free-living algae. The specificity of this association is beginning to be understood; however, the importance of mucilage production has not been examined. The symbiosome membrane is the area of interface in this symbiosis and is presumably important in recognition and transfer of nutrients. Cultured Symbiodinium were labeled with a previously developed primary antibody that binds to symbiont mucilage (PC3) and visualized with a fluorescent secondary antibody on a confocal microscope to identify labeling in different clades and strains. Mucilage contained PC3 antigen in cultured zooxanthellae from clades A and B from a variety of hosts, except Montastrea faveolata which did not label. The algae from clades C, D, and H did not label (including those from M. faveolata). Biochemical analyses of the mucilage show 1.09 g/L of carbohydrate and 36.7 g/L of protein. Using a 13C source to assay photosynthetic carbon incorporation in the mucilage of dark and light incubated, cultured algae shows incorporation of 6.8%, indicating photosynthetically fixed carbon is a significant component. These data suggest that the mucilage may play a role in both specificity between host and symbiont and in the translocation of carbon to the host.
