Hydrothermal Vent Gastropod Research Articles

Hydrothermal vent gastropods from the same family (Provannidae) harbour ɛ‐ and γ‐proteobacterial endosymbionts

The discovery of new hydrothermal vent systems in the back-arc basins of the Western Pacific revealed chemosynthesis-based faunal communities distinct from those of other vents. These vents are dominated by two related gastropods (Alviniconcha spp. and Ifremeria nautilei) that harbour symbiotic bacteria in their gills. We used comparative 16S ribosomal RNA (rRNA) gene sequencing and in situ hybridization with rRNA-targeted probes to characterize the bacterial symbionts of Alviniconcha sp. and I. nautilei from the Manus Basin in the Western Pacific. The analyses revealed that these two gastropod species, although affiliated with the same family, harbour phylogenetically distant chemosymbionts, suggesting independent origins of these endosymbioses. The I. nautilei endosymbiont clusters with sulfur-oxidizing bacteria within the gamma-Proteobacteria, as is the case for all previously characterized endosymbionts from a wide diversity of host taxa harbouring thioautotrophic prokaryotes. In contrast, the Alviniconcha endosymbiont is affiliated with sulfur-oxidizing bacteria within the epsilon-Proteobacteria. These results show that bacteria from the epsilon-Proteobacteria are also capable of forming endosymbiotic associations with marine invertebrates from chemosynthetic environments. More generally, the endosymbiotic lifestyle is now shown to be distributed throughout all recognized classes of the Proteobacteria.

Role of thermal conditions in habitat selection by hydrothermal vent gastropods

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 305:1-15 (2005) - doi:10.3354/meps305001 Role of thermal conditions in habitat selection by hydrothermal vent gastropods Amanda E. Bates1,*, Verena Tunnicliffe1, Raymond W. Lee2 1Department of Biology, University of Victoria, PO Box 3020, Victoria, British Columbia V8W 3N5, Canada 2School of Biological Sciences, Washington State University, Pullman, Washington 99164-4236, USA *Email: bates.amanda@gmail.com ABSTRACT: Habitat selection by 3 Juan de Fuca Ridge gastropod species relates to their thermal environment. Both collections and images taken along transects document the small-scale abundance patterns of each species with respect to temperature and distance from vent flows. Lepetodrilus fucensis and Depressigyra globulus were most abundant at distances from vent flows of 0 to 25 cm in warm fluids with high temperature variability (10 ± 5°C) over several time scales. Both species were also abundant at 26 to 50 cm, where temperatures were lower with less variability (4 ± 1°C). Provanna variabilis was most abundant from 51 to 75 cm, where temperatures were stable (3 ± 0.5°C). All species were absent where maximum fluid temperatures reached 18°C and their substratum coverage was related to temperature. When presented with a choice in vent fluids from 10 to 2°C, L. fucensis and D. globulus moved to areas with temperatures above 5°C, while P. variabilis showed no preference. In species-specific temperature preference experiments, L. fucensis and D. globulus aggregated between 5 and 13°C, while P. variabilis occupied areas with significantly lower temperatures from 4 to 11°C. These experimental temperature preferences correspond with their thermal environments. Upper temperature limits are moderate; extreme abiotic variability in higher temperature fluids may constrain these 3 species. We conclude thermal conditions are a primary determinant of habitat selection, thereby driving gastropod abundance patterns. However, other factors likely contribute. Space competition nearest vent flows may result in the displacement of individuals of these species to low quality habitats. KEY WORDS: Thermal variability · Abundance patterns · Hydrothermal vent · Lepetodrilus fucensis · Depressigyra globulus · Provanna variabilis · Preferences Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 305. Online publication date: December 23, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Characterization and expression of genes from the RubisCO gene cluster of the chemoautotrophic symbiont of Solemya velum: cbbLSQO.

Chemoautotrophic endosymbionts residing in Solemya velum gills provide this shallow water clam with most of its nutritional requirements. The cbb gene cluster of the S. velum symbiont, including cbbL and cbbS, which encode the large and small subunits of the carbon-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO), was cloned and expressed in Escherichia coli. The recombinant RubisCO had a high specific activity, approximately 3 micromol min(-1) mg protein (-1), and a KCO2 of 40.3 microM. Based on sequence identity and phylogenetic analyses, these genes encode a form IA RubisCO, both subunits of which are closely related to those of the symbiont of the deep-sea hydrothermal vent gastropod Alviniconcha hessleri and the photosynthetic bacterium Allochromatium vinosum. In the cbb gene cluster of the S. velum symbiont, the cbbLS genes were followed by cbbQ and cbbO, which are found in some but not all cbb gene clusters and whose products are implicated in enhancing RubisCO activity post-translationally. cbbQ shares sequence similarity with nirQ and norQ, found in denitrification clusters of Pseudomonas stutzeri and Paracoccus denitrificans. The 3' region of cbbO from the S. velum symbiont, like that of the three other known cbbO genes, shares similarity to the 3' region of norD in the denitrification cluster. This is the first study to explore the cbb gene structure for a chemoautotrophic endosymbiont, which is critical both as an initial step in evaluating cbb operon structure in chemoautotrophic endosymbionts and in understanding the patterns and forces governing RubisCO evolution and physiology.

Novel forms of structural integration between microbes and a hydrothermal vent gastropod from the Indian Ocean.

Here we describe novel forms of structural integration between endo- and episymbiotic microbes and an unusual new species of snail from hydrothermal vents in the Indian Ocean. The snail houses a dense population of gamma-proteobacteria within the cells of its greatly enlarged esophageal gland. This tissue setting differs from that of all other vent mollusks, which harbor sulfur-oxidizing endosymbionts in their gills. The significantly reduced digestive tract, the isotopic signatures of the snail tissues, and the presence of internal bacteria suggest a dependence on chemoautotrophy for nutrition. Most notably, this snail is unique in having a dense coat of mineralized scales covering the sides of its foot, a feature seen in no other living metazoan. The scales are coated with iron sulfides (pyrite and greigite) and heavily colonized by epsilon- and delta-proteobacteria, likely participating in mineralization of the sclerites. This novel metazoan-microbial collaboration illustrates the great potential of organismal adaptation in chemically and physically challenging deep-sea environments.

An Ascomycete Commensal on the Gills of Bathynerita naticoidea, the Dominant Gastropod at Gulf of Mexico Hydrocarbon Seeps

The discovery of a fungal commensal on the gills of Bathynerita naticoidea, the dominant gastropod at petroleum seep communities located along the Gulf of Mexico upper continental slope (500-800 m), is reported. Light and electron micrographs revealed filamentous fungi of the class Ascomycetes and unidentified fungal bodies associated with the gill tissue of each of the 7 freshly collected specimens of B. naticoidea examined. Fungi were found attached to the surface of the gill cells, intercellularly, within the gill blood spaces, enclosed in otherwise empty intracellular vacuoles, and external but adjacent to the gill tissue. The exact nature of this fungal association is unknown; the fungi may act to detoxify the hydrocarbons and sulfide compounds of the seep environment, or may be parasites that have infected the gill tissue. Although chemoautotrophic and methanotrophic bacterial symbionts have been found previously within the gills of deep-sea (2200-3000 m) hydrothermal vent gastropods, there was no evidence of bacterial symbionts within the gills of B. naticoidea. This is the first report of a fungal association within gastropods endemic to hydrocarbon seep or hydrothermal vent

Symbiosis of the Hydrothermal Vent Gastropod Ifremeria nautilei (Provannidae) With Endobacteria-Structural Analyses and Ecological Considerations.

The gastropod Ifremeria nautilei lives in high abundance around deep-sea hydrothermal vents of the Western Pacific. The filaments of its ctenidium are very long and have a rigid axis with a hemocoelic vessel and a strongly ciliated epithelium. The flattened part of each filament largely consists of bacteriocytes that are distally filled with numerous gram-negative bacteria. The bacteria lie one by one in vacuoles that seem to be part of an interconnected tubular system. Some of the apical vacuoles regularly showed what could be openings to the ambient seawater. This special topological arrangement of the bacteria suggests that in a morphological series mirroring the supposed evolutionary pathway from extra- to intracellular symbioses, I. nautilei might correspond to an intermediate stage. The high sulfur content and the low stable carbon isotope values measured in this study, combined with corresponding data from the literature, indicate that I. nautilei is the host partner in a thiotrophic chemoautotrophic bacterial symbiosis. The importance of this symbiosis for the nutrition of the gastropod is underlined by the reduced size of the host's stomach. Unlike specimens of I. nautilei from the Manus Basin (Galchenko et al., 1992), the inspected specimens from the North Fiji Basin did not contain any methanotrophic bacteria in addition to the thiotrophic type. From the disparity in results, it may be concluded that this host species can develop different patterns of symbiosis either as an adaptation to local variances of hydrothermal vent fluid chemistry or as a consequence of genetic differentiation in the host.

New species, anatomy, and systematic position of the hydrothermal vent and hydrocarbon seep gastropod family Provannidae fam.n. (Caenogastropoda)

The anatomy of the hydrothermal vent gastropod Provanna is described. It is shown to be a primitive neotaenioglossan with mainly plesiomorphic features in all systems, including open pallial gonoducts, epiathroid nervous system with accessory pedal ganglia and a circulatory system where a considerable portion of the venous blood from the coelomic spaces enters the pallial skirt. Apomorphic features include the possession of an anterior notch, or short canal in the shell (and mantle edge), an annulated sensory pallial tentacle, paraspermatozoa modificd as nurse cells. multiple seminal receptacles, a posterior bursa copulatrix, and a renal oviduct with three distinct regions. the middle one expanded. Comparisons are madc with Abyssochrysos, a genus assumed to be a relict member of the Loxonematoidea, which appears to be the closest known relative. A new family. Provannidae fam.n., is created and tentatively included in the Loxonematoidea. The following new specics are described: Provanna segonzaci sp.n. (from hydrothermal vents at the Fiji Back Arc), P. laevis sp.n. (from hydrothermal seeps in the Gulf of California), P. sculpta sp.n. and P. admetoides sp.n. (from hydrocarbon seeps in the Gulf of Mexico). New records are added for previously described species of Provanna.