AME 66:63-75 (2012)  -  DOI: https://doi.org/10.3354/ame01559

Direct evidence for symbiont sequestration in the marine red tide ciliate Mesodinium rubrum

P. J. Hansen1,*, M. Moldrup1, W. Tarangkoon1,2, L. Garcia-Cuetos3, Ø. Moestrup3

1Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, Helsingør 3000, Denmark
2Faculty of Science and Fisheries Technology, Rajamangala University of Technology Srivijaya, Trang 92150, Thailand
3Phycology Laboratory, Department of Biology, University of Copenhagen, Øster Farimagsgade 2D, Copenhagen 1353, Denmark

ABSTRACT: The red tide ciliate Mesodinium rubrum (= Myrionecta rubra) is known to contain symbionts of cryptophyte origin. Molecular data have shown that the symbiont is closely related or similar to free-living species of the Teleaulax/Plagioselmis/Geminigera clade. This suggests that the symbiont of M. rubrum is either a temporary symbiont or a quite recently established symbiont. Here, we present data from a number of experiments in which we offered M. rubrum a phototrophic dinoflagellate and 8 different cryptophyte species belonging to 5 different clades. Mesodinium rubrum was only able to grow when fed the 2 cryptophyte species belonging to the genus Teleaulax, T. acuta and T. amphioxeia. Using the nucleomorph large subunit rDNA gene as marker, we were able to discriminate the 2 Teleaulax species, allowing monitoring of the exchange of the symbionts in M. rubrum. Over a period of 35 d, M. rubrum was able to exchange its symbionts from T. amphioxeia symbionts to T. acuta symbionts. This research suggests that M. rubrum can only utilize prey within the Teleaulax/Plagioselmis/Geminigera clade for sustained high growth rates and provides the first time-frame of endosymbiont replacement by M. rubrum.


KEY WORDS: Mesodinium rubrum · Symbionts · Ingestion · Cryptophytes


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Cite this article as: Hansen PJ, Moldrup M, Tarangkoon W, Garcia-Cuetos L, Moestrup Ø (2012) Direct evidence for symbiont sequestration in the marine red tide ciliate Mesodinium rubrum. Aquat Microb Ecol 66:63-75. https://doi.org/10.3354/ame01559

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