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Front. Microbiol. | doi: 10.3389/fmicb.2019.01153

Proteomic Basis of Symbiosis: A Heterologous Partner Fails to Duplicate Homologous Success in a Novel Cnidarian- Symbiodiniaceae Mutualism

  • 1Florida International University, United States

Reef corals and sea anemones form symbioses with unicellular symbiotic dinoflagellates. The molecular circumventions that underlie the successful intracellular colonization of hosts by symbionts are still largely unknown. We conducted proteomic analyses to determine molecular differences of Exaiptasia pallida anemones colonized by physiologically different symbiont species, in comparison with symbiont-free (aposymbiotic) anemones. We compared one homologous species, Symbiodinium linucheae, that is natively associated with the clonal Exaiptasia strain (CC7) to another heterologous species, Durusdinium trenchii, a thermally tolerant species that colonizes numerous coral species. This approach allowed the discovery of a core set of host genes that are differentially regulated as a function of symbiosis regardless of symbiont species. The findings revealed that symbiont colonization at higher densities requires circumvention of the host cellular immunological response, enhancement of ammonium regulation, and suppression of phagocytosis after a host cell in colonized. Furthermore, the heterologous symbionts failed to duplicate the same level of homologous colonization within the host, evidenced by substantially lower symbiont densities. This reduced colonization of D. trenchii correlated with its inability to circumvent key host systems including autophagy-suppressing modulators, cytoskeletal alteration, and isomerase activity. The larger capability of host molecular circumvention by homologous symbionts could be the result of a longer evolutionary history of host/symbiont interactions, which translates into a more finely tuned symbiosis. These findings are of great importance within the context of the response of reef corals to climate change since it has been suggested that coral may acclimatize to ocean warming by changing their dominant symbiont species.

Keywords: Symbiosis, Cnidarian, Exaiptasia pallida, Symbiodiniaceae, Symbiodinium linucheae, Durusdinium trenchii, Symbiosis core genes

Received: 05 Dec 2018; Accepted: 06 May 2019.

Edited by:

Joerg Graf, University of Connecticut, United States

Reviewed by:

Daniel J. Thornhill, National Science Foundation (NSF), United States
Verena Schrameyer, University of Copenhagen, Denmark  

Copyright: © 2019 Medrano, Merselis, Bellantuono and Rodriguez-Lanetty. 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(s) 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. Mauricio Rodriguez-Lanetty, Florida International University, Miami, United States, rodmauri@fiu.edu