Meeting Abstract
22.1 Monday, Jan. 4 Mucilage Secretion in Different Symbiodinium Strains MAZZILLO, Maria*; KEMPF, Stephen C.; Auburn University; Auburn University mmazzillo@gmail.com
Symbiodinium are brown, unicellular dinoflagellates that reside intracellularly in a variety of invertebrate hosts, including many cnidarians. In this mutualism, the endosymbiotic algae are enclosed in a symbiosome membrane (both host and symbiont-derived) and donate photosynthetically fixed carbon to their host in exchange for nutrients. Symbiodinium is a diverse genus of 8 clades with multiple strains in each clade. The specificity of the association between symbiont and host varies with some highly specific relationships and others of a more general nature. The symbiont secretes mucilage that lies at the interface between host and symbiont (as part of the symbiont contribution to the symbiosome membrane). Cultured Symbiodinium from a variety of clades were labeled with an antibody to symbiont mucilage (PC3; developed to a clade B alga cultured from Aiptasia pallida). The labeling was visualized with a fluorescent marker and examined with a confocal microscope. Previous work found PC3 antigen in cultured Symbiodinium from clades A and B but not in clades C and D. New mucilage markers are being developed to further characterize mucilage differences between clades. Biochemical analyses of the mucilage are also being performed to examine the protein and carbohydrate composition. Using 13C tagged Na-bicarbonate to label cultured algae in the dark and light and measuring the amount of 13C in the mucilage shows incorporation of 6.8%, indicating photosynthetically fixed carbon is a significant part of the mucilage in the strain of alga tested. These data suggest that the mucilage may play a role in both specificity (via host-symbiont interaction) and in translocation of carbon to the host.
