The Transcriptome of Bathymodiolus azoricus Gill Reveals Expression of Genes from Endosymbionts and Free-Living Deep-Sea Bacteria

Abstract

Deep-sea environments are largely unexplored habitats where a surprising number of species may be found in large communities, thriving regardless of the darkness, extreme cold, and high pressure. Their unique geochemical features result in reducing environments rich in methane and sulfides, sustaining complex chemosynthetic ecosystems that represent one of the most surprising findings in oceans in the last 40 years. The deep-sea Lucky Strike hydrothermal vent field, located in the Mid Atlantic Ridge, is home to large vent mussel communities where Bathymodiolus azoricus represents the dominant faunal biomass, owing its survival to symbiotic associations with methylotrophic or methanotrophic and thiotrophic bacteria. The recent transcriptome sequencing and analysis of gill tissues from B. azoricus revealed a number of genes of bacterial origin, hereby analyzed to provide a functional insight into the gill microbial community. The transcripts supported a metabolically active microbiome and a variety of mechanisms and pathways, evidencing also the sulfur and methane metabolisms. Taxonomic affiliation of transcripts and 16S rRNA community profiling revealed a microbial community dominated by thiotrophic and methanotrophic endosymbionts of B. azoricus and the presence of a Sulfurovum-like epsilonbacterium.

In Situ Determination of Bacterial Growth in Mixing Zone of Hydrothermal Vent Field on the Hatoma Knoll, Southern Okinawa Trough

“…In this study, the 16S rRNA gene sequences of Epsilonproteobacteria from a digestive tract of the Bathymodiolus have either possibility of a feed from mixing-zone bacterial population or a member of normal flora (Egas et al 2012;Van Horn et al 2011) . Fig 33.2 DGGE band patterns of the water sample before (a) and after (b) the incubation with the seeds water collected from plume and Bathymodiolus colony.…”

An Insightful Model to Study Innate Immunity and Stress Response in Deep‐Sea Vent Animals: Profiling the Mussel Bathymodiolus azoricus

“…The transcriptome sequencing of gill tissues from the mussel B. azoricus revealed a set of genes of bacterial origin, providing a functional insight into the microbial vent community [71]. The transcripts supported a metabolically active microbiome and a variety of bacterial mechanisms and pathways, among which the fixation of carbon, the use of nitrate as a terminal acceptor of electrons and oxidation of sulfur and methane.…”

Differential gene expression in the mussel <i>Bathymodiolus azoricus</i> from the Menez Gwen and Lucky Strike deep-sea hydrothermal vent sites

“…Two replicate PCR were amplified from the same sample for each primer set, quantified by fluorimetry with PicoGreen (Invitrogen, CA, USA), pooled at equimolar concentrations and sequenced in the A direction with GS 454 FLX Titanium chemistry, according to manufacturer's instructions (Roche, 454 Life Sciences, Brandford, CT, USA). The raw data from 454 pyrosequencing were processed as described in Egas et al (2012). The high quality sequences were clustered together by uclust v2.1 (Edgar et al, 2010) with a similarity of 97 %.…”

“…The clustered sequences were then assembled by Cap3 (Huang et al, 1999) to produce OTU (Operational Taxonomic Units). The OTU were searched by NCBI BLAST against RDP, release 10 update 24 (Ribosomal Database Project) with a cut-off of 1e −50 to identify the taxa (16S RNA sequences of closely related microorganisms) as in Egas et al (2012).…”

“…Most genes were designated for their relevance in innate immunity and for corresponding to the immune function categories as defined in Bettencourt et al (2010). In addition, bacterial genes ensued from our metatranscriptome characterization were also analyzed (Egas et al, 2012). Keeping in line with the assumption that geographically different vent mussels will adopt different physiological statuses in relation to their environmental settings, we also assumed that the relative abundance of methanotrophic and sulfide oxidizing endosymbiotic bacteria would differ between LS and MG mussels as previously reported by other researchers (Duperron et al, 2005(Duperron et al, , 2006.…”