title: Post-capture immune gene expression studies in the deep-sea hydrothermal vent mussel Bathymodiolus azoricus acclimatized to atmospheric pressure.
abstract: Deep-sea hydrothermal vents are extreme habitats that are distributed worldwide in association with volcanic and tectonic events, resulting thus in the establishment of particular environmental conditions, in which high pressure, steep temperature gradients, and potentially toxic concentrations of sulfur, methane and heavy metals constitute driving factors for the foundation of chemosynthetic-based ecosystems. Of all the different macroorganisms found at deep-sea hydrothermal vents, the mussel Bathymodiolus azoricus is the most abundant species inhabiting the vent ecosystems from the Mid-Atlantic Ridge (MAR). In the present study, the effect of long term acclimatization at atmospheric pressure on host-symbiotic associations were studied in light of the ensuing physiological adaptations from which the immune and endosymbiont gene expressions were concomitantly quantified by means of real-time PCR. The expression of immune genes at 0 h, 12 h, 24 h, 36 h, 48 h, 72 h, 1 week and 3 weeks post-capture acclimatization was investigated and their profiles compared across the samples tested. The gene signal distribution for host immune and bacterial genes followed phasic changes in gene expression at 24 h, 1 week and 3 weeks acclimatization when compared to other time points tested during this temporal expression study. Analyses of the bacterial gene expression also suggested that both bacterial density and activity could contribute to shaping the intricate association between endosymbionts and host immune genes whose expression patterns seem to be concomitant at 1 week acclimatization. Fluorescence in situ hybridization was used to assess the distribution and prevalence of endosymbiont bacteria within gill tissues confirming the gradual loss of sulfur-oxidizing (SOX) and methane-oxidizing (MOX) bacteria during acclimatization. The present study addresses the deep-sea vent mussel B. azoricus as a model organism to study how acclimatization in aquaria and the prevalence of symbiotic bacteria are driving the expression of host immune genes. Tight associations, unseen thus far, suggest that host immune and bacterial gene expression patterns reflect distinct physiological responses over the course of acclimatization under aquarium conditions.
authors.affiliation: Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal; IMAR-Center of the University of the Azores, LARSyS Associate Laboratory, 9901-862 Horta, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Barros
authors.affiliation: The National Institute of Oceanography (NIO) Dona Paula, Biological Oceanography Division, 403 004 Goa, India.
authors.forename: Baby
authors.initials: B
authors.lastname: Divya
authors.affiliation: IMAR-Center of the University of the Azores, LARSyS Associate Laboratory, 9901-862 Horta, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Martins
authors.affiliation: Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal; IMAR-Center of the University of the Azores, LARSyS Associate Laboratory, 9901-862 Horta, Portugal.
authors.forename: Frederic
authors.initials: F
authors.lastname: Vandeperre
authors.affiliation: Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal; IMAR-Center of the University of the Azores, LARSyS Associate Laboratory, 9901-862 Horta, Portugal.
authors.forename: Ricardo Serrão
authors.initials: RS
authors.lastname: Santos
authors.affiliation: IMAR-Center of the University of the Azores, LARSyS Associate Laboratory, 9901-862 Horta, Portugal; MARE-Marine and Environmental Science Center, University of the Azores, 9901-862 Horta, Azores, Portugal. Electronic address: raul@uac.pt.
authors.forename: Raul
authors.initials: R
authors.lastname: Bettencourt
mesh_terms: D000064:Acclimatization / Q000276:immunology*; D000818:Animals; D001267:Atlantic Ocean; D001274:Atmospheric Pressure; D049872:Bivalvia / Q000235:genetics / Q000276:immunology*; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D005786:Gene Expression Regulation / Q000276:immunology*; D005880:Gills / Q000276:immunology / Q000382:microbiology; D060086:Hydrothermal Vents; D007700:Kinetics; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D017931:DNA Primers
keywords: Deep-sea hydrothermal vent; Endosymbiont bacteria; Gene expression; Long term acclimatization; Molluscan immune system