Meeting Abstract
Glycan-lectin interactions are a fundamental mechanism of interpartner communication involved in innate immunity and host-microbe interactions. During onset of cnidarian-dinoflagellate symbiosis, cnidarian gastrodermal cells bind sugar residues on their algal partners. These algal glycans are important for recognition and may in part mediate host-symbiont specificity. We aimed to manipulate the Symbiodinium minutum glycome to determine the effect of specific glycan enrichment and simplification on symbiont colonization success. S. minutum cultures were treated with two different mannosidase inhibitors, kifunensine and swainsonine, which directly inhibit endogenous glycan biosynthesis pathways in the ER and Golgi, respectively. To test for efficacy, cultures were incubated with lectin-conjugated fluorophores that specifically labeled high-mannose glycans. Flow cytometric analysis revealed that both kifunensine- and swainsonine-treated cultures showed significant enrichment for high-mannose compared to untreated cultures. After confirming high-mannose enrichment, we then compared colonization success of each culture in the symbiotic sea anemone, Aiptasia pallida. Colonized hosts were imaged three days after inoculation. Kifunensine-treated cells had significantly lower colonization compared to untreated cells, measured via symbiont density. A similar decrease in colonization was found with S. minutum cells modified via glycosidase surface cleavage. Together, these results suggest that simplified glycans decrease the colonization success of Symbiodinium, and highlight the importance of complex glycans in symbiosis recognition.
