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

Elsa Alverca, Isabelle C. Biegala, Gabrielle M. Kennaway, Jane Lewis, Susana Franca

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)523-530
Number of pages8
JournalEuropean Journal of Phycology
Volume37
Issue number4
DOIs
Publication statusPublished - Nov 2002

Keywords

  • Confocal microscopy
  • Dinoflagellates
  • Gyrodinium instriatum
  • In situ hybridization
  • Intracellular bacteria
  • Oligonucleotide probes
  • TEM
  • Ultrastructure

Fingerprint

Dive into the research topics of 'In situ identification and localization of bacteria associated with Gyrodinium instriatum (Gymnodiniales, Dinophyceae) by electron and confocal microscopy'. Together they form a unique fingerprint.

Cite this