@article {3700, title = {Colonization of plant substrates at hydrothermal vents and cold seeps in the northeast Atlantic and Mediterranean and occurrence of symbiont-related bacteria.}, journal = {Front Microbiol}, volume = {6}, year = {2015}, month = {2015}, pages = {162}, abstract = {

Reducing conditions with elevated sulfide and methane concentrations in ecosystems such as hydrothermal vents, cold seeps or organic falls, are suitable for chemosynthetic primary production. Understanding processes driving bacterial diversity, colonization and dispersal is of prime importance for deep-sea microbial ecology. This study provides a detailed characterization of bacterial assemblages colonizing plant-derived substrates using a standardized approach over a geographic area spanning the North-East Atlantic and Mediterranean. Wood and alfalfa substrates in colonization devices were deployed for different periods at 8 deep-sea chemosynthesis-based sites in four distinct geographic areas. Pyrosequencing of a fragment of the 16S rRNA-encoding gene was used to describe bacterial communities. Colonization occurred within the first 14 days. The diversity was higher in samples deployed for more than 289 days. After 289 days, no relation was observed between community richness and deployment duration, suggesting that diversity may have reached saturation sometime in between. Communities in long-term deployments were different, and their composition was mainly influenced by the geographical location where devices were deployed. Numerous sequences related to horizontally-transmitted chemosynthetic symbionts of metazoans were identified. Their potential status as free-living forms of these symbionts was evaluated based on sequence similarity with demonstrated symbionts. Results suggest that some free-living forms of metazoan symbionts or their close relatives, such as Epsilonproteobacteria associated with the shrimp Rimicaris exoculata, are efficient colonizers of plant substrates at vents and seeps.

}, issn = {1664-302X}, doi = {10.3389/fmicb.2015.00162}, author = {Szafranski, Kamil M and Deschamps, Philippe and Cunha, Marina R and Sylvie M Gaudron and S{\'e}bastien Duperron} } @article {3761, title = {Epsilonproteobacteria as gill epibionts of the hydrothermal vent gastropod Cyathermia naticoides (North East-Pacific Rise)}, journal = {Marine Biology}, volume = {162}, year = {2015}, month = {11 D{\'e}c 2014}, pages = {435-448}, abstract = {

Mollusks, and particularly gastropods, are one of the major taxonomic groups at vents. In these ecosystems, devoid of light, chemoautotrophic bacteria are at the base of the food web and symbiotic association between metazoa and these bacteria is numerous. Nevertheless, apart few {\textquotedblleft}large-size{\textquotedblright} well-known species, the {\textquotedblleft}small-size{\textquotedblright} gastropods (shell \<5\ mm), although very abundant, remain poorly studied regarding symbioses. We investigated here Cyathermia naticoides (War{\'e}n and Bouchet in Zool Scr 18(1), 1989), a small coiled gastropod found in abundance on the East Pacific Rise among Riftia pachyptila tubes, and usually inferred to graze on tubeworm bacterial cover, and/or filter feeding. Among mollusks, symbioses are well known in large species and almost exclusively rely on sulfide or methane-oxidizing proteobacterial endosymbionts, occurring within the host tissues in gill epithelial bacteriocytes. Combining several approaches (molecular biology, microscopy, stable isotopes analyses), we described here an unusual symbiosis, where autotrophic filamentous Epsilonproteobacteria are located extracellularly, at the base of host gill filaments. Numerous endocytotic lysosome-like structures were observed in the gill epithelium of the animal suggesting bacteria may contribute to its nutrition through intracellular digestion by gill cells. Additional food source by non-symbiotic proteobacteria grazed on R. pachyptila tubes could complete the diet. The possible role of temperature in the selection of Epsilon- vs Gammaproteobacterial partners is discussed.

}, url = {http://link.springer.com/article/10.1007/s00227-014-2591-7$\#$}, author = {Magali Zbinden and Marqu{\'e}, Lise and Sylvie M Gaudron and Juliette Ravaux and Nelly L{\'e}ger and S{\'e}bastien Duperron} } @article {3701, title = {Direct evidence for maternal inheritance of bacterial symbionts in small deep-sea clams (Bivalvia: Vesicomyidae).}, journal = {Naturwissenschaften}, volume = {101}, year = {2014}, month = {2014 May}, pages = {373-83}, abstract = {

Bacterial symbiont transmission is a key step in the renewal of the symbiotic interaction at each host generation, and different modes of transmission can be distinguished. Vesicomyidae are chemosynthetic bivalves from reducing habitats that rely on symbiosis with sulfur-oxidizing bacteria, in which two studies suggesting vertical transmission of symbionts have been published, both limited by the imaging techniques used. Using fluorescence in situ hybridization and transmission electron microscopy, we demonstrate that bacterial symbionts of Isorropodon bigoti, a gonochoristic Vesicomyidae from the Guiness cold seep site, occur intracellularly within female gametes at all stages of gametogenesis from germ cells to mature oocytes and in early postlarval stage. Symbionts are completely absent from the male gonad and gametes. This study confirms the transovarial transmission of symbionts in Vesicomyidae and extends it to the smaller species for which no data were previously available.

}, keywords = {Animals, Bacterial Physiological Phenomena, Bivalvia, Female, Germ Cells, Gonads, In Situ Hybridization, Fluorescence, Male, Microscopy, Electron, Transmission, Oceans and Seas, Symbiosis}, issn = {1432-1904}, doi = {10.1007/s00114-014-1165-3}, author = {Szafranski, Kamil M and Sylvie M Gaudron and S{\'e}bastien Duperron} } @article {3216, title = {A microbiological and biogeochemical investigation of the cold seep tubeworm Escarpia southwardae (Annelida: Siboglinidae): Symbiosis and trace element composition of the tube}, journal = {Deep-Sea Research Part I - Oceanographic Research Papers}, year = {2014}, doi = {10.1016/J.dsr.2014.05.006}, author = {S{\'e}bastien Duperron and Sylvie M Gaudron and Lema{\^\i}tre, Nolwenn and Bayon, Germain} }