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Front. Microbiol. | doi: 10.3389/fmicb.2018.00842

Subtle differences in symbiont cell surface glycan profiles do not explain species-specific colonization rates in a model cnidarian-algal symbiosis

 John E. Parkinson1*,  Trevor R. Tivey1, Paige E. Mandelare2,  Donovon A. Adpressa2,  Sandra Loesgen2 and Virginia M. Weis1
  • 1Integrative Biology, Oregon State University, United States
  • 2Chemistry, Oregon State University, United States

Mutualisms between cnidarian hosts and dinoflagellate endosymbionts are foundational to coral reef ecosystems. These symbioses are often re-established every generation with high specificity, but gaps remain in our understanding of the cellular mechanisms that control symbiont recognition and uptake dynamics. Here, we tested whether differences in glycan profiles among different symbiont species account for the different rates at which they initially colonize aposymbiotic polyps of the model sea anemone Aiptasia (Exaiptasia pallida). First, we used a lectin array to characterize the glycan profiles of colonizing Symbiodinium minutum (ITS2 type B1) and non-colonizing S. pilosum (ITS2 type A2), finding subtle differences in the binding of lectins EEL and UDA that distinguish between high-mannoside and hybrid-type protein linked glycans. Next, we enzymatically cleaved glycans from the surfaces of S. minutum cultures and followed their recovery using flow cytometry, establishing a 48-72 hour glycan turnover rate for this species. Finally, we exposed aposymbiotic host polyps to cultured S. minutum cells masked by EEL or UDA lectins for 48 hours, then measured cell densities the following day. We found no effect of glycan masking on symbiont density, providing further support to the hypothesis that glycan-lectin interactions are more important for post-phagocytic persistence of specific symbionts than they are for initial uptake. We also identified several methodological and biological factors that may limit the utility of studying glycan masking in the Aiptasia system.

Keywords: Aiptasia, Exaiptasia pallida, Glycans, Lectin array, recognition, specificity, Symbiodinium

Received: 10 Jan 2018; Accepted: 12 Apr 2018.

Edited by:

Sebastian Fraune, Christian-Albrechts-Universität zu Kiel, Germany

Reviewed by:

Malcolm Hill, University of Richmond, United States
Silvia Bulgheresi, Universität Wien, Austria  

Copyright: © 2018 Parkinson, Tivey, Mandelare, Adpressa, Loesgen and Weis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. John E. Parkinson, Oregon State University, Integrative Biology, 3029 Cordley Hall, Corvallis, 97331, OR, United States, jeverettparkinson@gmail.com