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Metatranscriptomics profile of the gill microbial community during Bathymodiolus azoricus aquarium acclimatization at atmospheric pressure

1 Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal
2 MARE-Marine and Environmental Sciences Centre, 9901-862 Horta, Portugal
3 Next Generation Sequencing Unit-BIOCANT; Parque Tecnológico de Cantanhede, Núcleo 04, Lote 8, 3060-197 Cantanhede, Portugal
4 Harvard University, Informatics and Scientific Applications, 38 Oxford Street, Cambridge, MA 02138-2020, United States
5 Harvard University, Biological Laboratories, Room 3085, 16 Divinity Avenue, Cambridge, MA 02138-2020, United States
6 OKEANOS Center, Faculty of Science and Technology, University of the Azores, 9901-862 Horta, Portugal

Topical Section: Recent Discoveries in Archaea Research

Background: The deep-sea mussels Bathymodiolus azoricus (Bivalvia: Mytilidae) are the dominant macrofauna subsisting at the hydrothermal vents site Menez Gwen in the Mid-Atlantic Ridge (MAR). Their adaptive success in such challenging environments is largely due to their gill symbiotic association with chemosynthetic bacteria. We examined the response of vent mussels as they adapt to sea-level environmental conditions, through an assessment of the relative abundance of host-symbiont related RNA transcripts to better understand how the gill microbiome may drive host-symbiont interactions in vent mussels during hypothetical venting inactivity. Results: The metatranscriptome of B. azoricus was sequenced from gill tissues sampled at different time-points during a five-week acclimatization experiment, using Next-Generation-Sequencing. After Illumina sequencing, a total of 181,985,262 paired-end reads of 150 bp were generated with an average of 16,544,115 read per sample. Metatranscriptome analysis confirmed that experimental acclimatization in aquaria accounted for global gill transcript variation. Additionally, the analysis of 16S and 18S rRNA sequences data allowed for a comprehensive characterization of host-symbiont interactions, which included the gradual loss of gill endosymbionts and signaling pathways, associated with stress responses and energy metabolism, under experimental acclimatization. Dominant active transcripts were assigned to the following KEGG categories: “Ribosome”, “Oxidative phosphorylation” and “Chaperones and folding catalysts” suggesting specific metabolic responses to physiological adaptations in aquarium environment. Conclusions: Gill metagenomics analyses highlighted microbial diversity shifts and a clear pattern of varying mRNA transcript abundancies and expression during acclimatization to aquarium conditions which indicate change in bacterial community activity. This approach holds potential for the discovery of new host-symbiont associations, evidencing new functional transcripts and a clearer picture of methane metabolism during loss of endosymbionts. Towards the end of acclimatization, we observed trends in three major functional subsystems, as evidenced by an increment of transcripts related to genetic information processes; the decrease of chaperone and folding catalysts and oxidative phosphorylation transcripts; but no change in transcripts of gluconeogenesis and co-factors-vitamins.
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Keywords Bathymodiolus azoricus; long term acclimatization; metatranscriptome; RNA-seq; host-microbe interactions; symbionts; hydrothermal vent

Citation: Inês Barros, Hugo Froufe, George Marnellos, Conceição Egas, Jennifer Delaney, Michele Clamp, Ricardo Serrão Santos, Raul Bettencourt. Metatranscriptomics profile of the gill microbial community during Bathymodiolus azoricus aquarium acclimatization at atmospheric pressure. AIMS Microbiology, 2018, 4(2): 240-260. doi: 10.3934/microbiol.2018.2.240


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Copyright Info: © 2018, Inês Barros, licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

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