Project description:Colonization of deep-sea hydrothermal vents by invertebrates was made efficient through their adaptation to a symbiotic lifestyle with chemosynthetic bacteria, the primary producers of these ecosystems. Anatomical adaptations such as the establishment of specialized cells or organs have been evidenced in numerous deep-sea invertebrates. However, very few studies detailed global inter-dependencies between host and symbionts in these ecosystems. In this study, we proposed to describe, using a proteo-transcriptomic approach, the effects of symbionts on the deep-sea mussel Bathymodiolus azoricus’ molecular biology. We induced an in situ depletion of symbionts and compared the proteo-transcriptome of the gills of mussels in three conditions: symbiotic mussels (natural population), symbiont-depleted mussels and aposymbiotic mussels
Project description:Bathymodiolus mussels inhabiting deep-sea hydrothermal vents harbor bacterial symbionts in their gills, which support the animals’ diet. While the basic mechanisms of energy generation and CO2 fixation that drive these symbioses are largely established, details of molecular interactions between the symbiotic partners and adaptations to their respective habitats remain unknown. In this study, we therefore comparatively examined the genomes and proteomes of two Bathymodiolus hosts and their respective symbionts from different geographical locations. Two mussel species were proteomically compared: i) B. thermophilus mussel containing sulfur-oxidizing symbiont from the east pacific rise. thermophilus and ii) B. azoricus containing thiotrophic and methanotrophic symbionts from the mid-atlantic ridge. Symbionts (for both species) and host components (for B. azoricus) were selectively enriched using a multi-step centrifugation procedure. Enriched host and symbiont fractions along with unenriched gill foot tissue were subject to in-depth semi-quantitative proteomic analyses using the orbitrap and velos mass spectrometers. Proteins were quantified based on their spectral counts using the normalized spectral abundance factor (NSAF) method. We identified common strategies of metabolic interactions that provide mutual nutritional support between host and symbionts, such as the detoxification of ambient sulfide by the Bathymodiolus host, which provides a stable thiosulfate reservoir for the thiotrophic symbionts, and a putative amino acid cycling mechanism that could supply the host with symbiont-derived amino acids. A suite of genes and proteins putatively related to virulence or defense functions was particularly abundant in the B. thermophilus symbiont, compared to its symbiont relatives, and may pose a host species-specific adaptation. Our results reveal both, a high degree of integration between the symbiotic partners, and great potential to adapt to the prevailing environment, which facilitate the holobiont’s survival in its hydrothermal vent habitat.
Project description:Bathymodiolin mussels are a group of bivalves associated with deep-sea reducing habitats, such as hydrothermal vents and cold seeps. These mussels usually engage in an obligatory symbiosis with sulfur and/or methane oxidizing Gammaproteobacteria. In addition to these bacteria, Bathymodiolus heckerae that inhabit gas and oil seeps in Campeche Bay, the southern Gulf of Mexico, host bacteria phylogenetically with the Cycloclasticus genus. We recently discovered the capability for short-chain alkane degradation in draft genomes of symbiotic Cycloclasticus. With proteomics, we investigated whether the genes required for this process are expressed by the symbionts.
Project description:The project was designed to explore biological rhythms in the hydrothermal vent mussel Bathymodiolus azoricus. The experiment provides the first high-resolution temporal transcriptomes of an hydrothermal species, both in situ and in the laboratory. For each condition, 5 mussels were sampled every 2h 4min for 24h 48min.
Project description:Bathymodiolus azoricus is a deep-sea mussel found in the hydrothermal vent fields of the Mid-Atlantic Ridge. It lives in symbiosis with sulfur- and methane-oxidizing γ-proteobacteria within its gills. In our study, we aimed to understand the metabolic and physiological interconnections between the symbiotic partners. For this purpose, symbionts and host were physically separated using density gradient centrifugation. This procedure yielded a symbiont-enriched gradient pellet fraction and a supernatant fraction enriched in host components. The cytosolic and membrane-associated proteome of both these fractions along with whole gill and foot tissue of the mussel were then investigated through 1D-PAGE LC-MS/MS. Proteins were quantified based on their spectral counts using the NSAF method. For efficient identification, sequences from evolutionarily related endosymbiotic and free-living bacteria and from bivalve host relatives were compiled into a comprehensive protein database. A total of 3178 host and symbiont proteins were identified from all samples.
Project description:Bathymodiolus childressi is a species of deep-sea mussels found predominantly in the Gulf of Mexico. It colonizes cold seeps such as brine pool and oil seeps. The success of these animals in such environment is thought to be due to the symbiotic association of the mussel host with several species of bacteria. The aim of this study is to understand the role of the different partners involved in the symbiotic system using various “-omics” approaches. In addition to protein identification we used the mass spectrometry data generated and submitted with this project to derive the stable carbon isotope ratios for the different members of the symbiosis using the direct Protein-SIF method. The respective isotope pattern file and SIF computation files are included with this submission.