CNRS, LM2E, UMR6197, BP70, Plouzané, France.
ISME J. 2012 Mar;6(3):597-609. doi: 10.1038/ismej.2011.133. Epub 2011 Oct 13.
The caridean shrimp Rimicaris exoculata dominates the fauna at several Mid-Atlantic Ridge hydrothermal vent sites. This shrimp has an enlarged gill chamber, harboring a dense ectosymbiotic community of chemoautotrophic bacteria associated with mineral oxide deposits. Until now, their acquisition is not fully understood. At three hydrothermal vent sites, we analyzed the epibionts diversity at different moult stages and also in the first stages of the shrimp life (eggs, hatched eggs (with larvae) and juveniles). Hatched eggs associated with young larvae were collected for the first time directly from gravid females at the Logachev vent site during the Serpentine cruise. An approach using 16S rRNA clone libraries, scanning and transmission electron microscopy, and fluorescent in situ hybridization was used. Molecular results and microscope observations indicated a switch in the composition of the bacterial community between early R. exoculata life cycle stage (egg libraries dominated by the Gammaproteobacteria) and later stages (juvenile/adult libraries dominated by the Epsilonproteobacteria). We hypothesized that the epibiotic phylotype composition could vary according to the life stage of the shrimp. Our results confirmed the occurrence of a symbiosis with Gammaproteobacteria and Epsilonproteobacteria, but more complex than previously assumed. We revealed the presence of active type-I methanotrophic bacteria colonizing the cephalothorax of shrimps from the Rainbow site. They were also present on the eggs from the Logachev site. This could be the first 'epibiotic' association between methanotrophic bacteria and hydrothermal vent crustacean. We discuss possible transmission pathways for epibionts linked to the shrimp life cycle.
铠甲虾 Rimicaris exoculata 是中大西洋海脊多个热液喷口栖息地里占主导地位的动物。这种虾的鳃腔增大，栖息着与其矿化氧化物沉积物相关的、密集的共生异养细菌群落。直到现在，人们对其获取方式仍不完全了解。在三个热液喷口地点，我们在不同蜕皮阶段和虾生命的早期阶段（卵、孵化卵（带幼虫）和幼体）分析了附生生物多样性。首次直接从 Logachev 喷口的 Serpentine 巡游期间的孕虾中收集了带有幼幼虫的孵化卵。采用 16S rRNA 克隆文库、扫描和透射电子显微镜以及荧光原位杂交的方法。分子结果和显微镜观察表明，在早期 R. exoculata 生命周期阶段（以γ变形菌为主的卵文库）和后期阶段（以ε变形菌为主的幼体/成体文库）之间，细菌群落的组成发生了转变。我们假设，附生生物型的组成可能因虾的生命阶段而异。我们的研究结果证实了与γ变形菌和ε变形菌共生的发生，但比以前的假设更为复杂。我们揭示了活跃的 I 型甲烷营养细菌存在于 Rainbow 站点虾的头胸甲上。它们也存在于 Logachev 站点的卵上。这可能是甲烷营养细菌与热液喷口甲壳类动物之间的首次“附生”关联。我们讨论了与虾生命周期相关的附生生物可能的传播途径。
