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In situ identification and localization of bacteria associated with Gyrodinium instriatum (Gymnodiniales, Dinophyceae) by electron and confocal microscopy

Alverca, Elsa and Biegala, Isabelle and Kennaway, Gabrielle and Lewis, Jane and Franca, Susana (2002) In situ identification and localization of bacteria associated with Gyrodinium instriatum (Gymnodiniales, Dinophyceae) by electron and confocal microscopy. European Journal of Phycology, 37 (4). pp. 523-530. ISSN 0967-0262

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Official URL: http://dx.doi.org/10.1017/S0967026202003955

Abstract

The presence of intracellular bacteria in the dinoflagellate Gyrodinium instriatum Freudenthal & Lee has previously been described but the bacterial flora associated with this species has not been characterized. In this study, new results of transmission electron microscopy (TEM) and in situ hybridization using several bacterial group-specific oligonucleotide probes are presented. The long-term association of endocytoplasmic and endonuclear bacteria with G. instriatum has been confirmed. All endonuclear and most of the endocytoplasmic bacteria labelled were identified as belonging to the betaproteobacteria. Large clusters of Cytophaga-Flavobacterium-Bacteroides (CFB) were labelled and observed in the cytoplasm of the dinoflagellate cells, but were absent from the nucleus. Gammaproteobacteria were only observed outside the dinoflagellates. No alphaproteobacteria were detected either free-living or intracellular. Empirical observation of intracellular CFB reflected a degradation process of moribund dinoflagellate cells, whereas the systematic colonization of dinoflagellate nucleoplasm by betaproteobacteria suggested a true symbiotic relationship. Natural colonization may have occurred, perpetuated by vertical transmission of intracellular bacteria to the dinoflagellate daughter cells, via a pool of bacteria sequestered within the nucleus. Dividing bacteria were observed in the nucleus and equilibrium may be maintained by release of endonuclear bacteria to the cytoplasm through nuclear envelope constrictions.

Item Type:Article
Additional Information:Online ISSN 1469-4433
Research Community:University of Westminster > Life Sciences, School of
ID Code:306
Deposited On:01 Dec 2005
Last Modified:21 Dec 2009 16:42

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