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Dual Symbiosis in a Bathymodiolus sp. Mussel from a Methane Seep on the Gabon Continental Margin (Southeast Atlantic): 16S rRNA Phylogeny and Distribution of the Symbionts in Gills

IFREMER Départment Environnement Profond, Centre de Brest, Plouzané, Germany.
Applied and Environmental Microbiology (Impact Factor: 3.95). 05/2005; 71(4):1694-700. DOI: 10.1128/AEM.71.4.1694-1700.2005
Source: PubMed

ABSTRACT Deep-sea mussels of the genus Bathymodiolus (Bivalvia: Mytilidae) harbor symbiotic bacteria in their gills and are among the dominant invertebrate species at cold seeps and hydrothermal vents. An undescribed Bathymodiolus species was collected at a depth of 3,150 m in a newly discovered cold seep area on the southeast Atlantic margin, close to the Zaire channel. Transmission electron microscopy, comparative 16S rRNA analysis, and fluorescence in situ hybridization indicated that this Bathymodiolus sp. lives in a dual symbiosis with sulfide- and methane-oxidizing bacteria. A distinct distribution pattern of the symbiotic bacteria in the gill epithelium was observed, with the thiotrophic symbiont dominating the apical region and the methanotrophic symbiont more abundant in the basal region of the bacteriocytes. No variations in this distribution pattern or in the relative abundances of the two symbionts were observed in mussels collected from three different mussel beds with methane concentrations ranging from 0.7 to 33.7 microM. The 16S rRNA sequence of the methanotrophic symbiont is most closely related to those of known methanotrophic symbionts from other bathymodiolid mussels. Surprisingly, the thiotrophic Bathymodiolus sp. 16S rRNA sequence does not fall into the monophyletic group of sequences from thiotrophic symbionts of all other Bathymodiolus hosts. While these mussel species all come from vents, this study describes the first thiotrophic sequence from a seep mussel and shows that it is most closely related (99% sequence identity) to an environmental clone sequence obtained from a hydrothermal plume near Japan.

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    • "The presence of methanotrophic and thiotrophic bacterial endosymbiont in B. azoricus gill tissue was determined according to Duperron et al. (2005) with slight modifications [15] [23]. Gill tissues were fixed in 5% buffered formalin and processed for paraffin embedding according to standard protocol. "
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    ABSTRACT: Deep-sea hydrothermal vents are extreme habitats that are distributed worldwide in association with volcanic and tectonic events, resulting thus in the establishment of particular environmental conditions, in which high pressure, steep temperature gradients, and potentially toxic concentrations of sulfur, methane and heavy metals constitute driving factors for the foundation of chemosynthetic-based ecosystems. Of all the different macroorganisms found at deep-sea hydrothermal vents, the mussel Bathymodiolus azoricus is the most abundant species inhabiting the vent ecosystems from the Mid-Atlantic Ridge (MAR). In the present study, the effect of long term acclimatization at atmospheric pressure on host-symbiotic associations were studied in light of the ensuing physiological adaptations from which the immune and endosymbiont gene expressions were concomitantly quantified by means of real-time PCR.
    Fish &amp Shellfish Immunology 11/2014; 42(1):159-170. DOI:10.1016/j.fsi.2014.10.018 · 3.03 Impact Factor
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    • "m À 2 ), and cover large areas paved with authigenic carbonate crusts (up to 1400 m 2 ) within the pockmark (Olu-LeRoy et al., 2007; Marcon et al., 2014). Specimens were part of a large bush sampled using a BushMaster device (Penn State University, C.R. Fisher) manipulated by the arm of the ROV Victor6000 (dive 426; 5.7981S, 9.7111E, 3152 m depth) in the central zone of the pockmark (Duperron et al., 2005; Olu-LeRoy et al., 2007; Cowart et al., 2013). Hydrogen sulfide is undetectable in bottom waters at Regab, but present in anoxic methane-rich sediment below the seawater/sediment interface (Olu-LeRoy et al., 2007; Cambon- Bonavita et al., 2009; Ristova et al., 2012). "
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    • "Keeping in line with the assumption that geographically distinct vent mussels will adopt different physiological statuses in relation to their environmental conditions, we also surmised that the relative abundance of methanotrophic and sulfide oxidizing endosymbiotic bacteria would differ between Menez Gwen and Lucky Strike mussels as previously reported by other researchers [13] [14] [6]. "
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