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  • 1
    Electronic Resource
    Electronic Resource
    Metabolic and blood characteristics of the hydrothermal vent tube-worm Riftia pachyptila (1984)
    Springer
    Marine biology 83 (1984), S. 109-124 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of the hydrothermal vent pogonophoran Riftia pachyptila Jones were collected by submersible at a depth of 2 600 m at the 21°N hydrothermal vent site on the East Pacific Rise (20°50′N, 109°06′W) in April and May of 1982. The worms were maintained in pressurized aquaria for up to 45 d for metabolic studies. Consumption of O2 was regulated down to low PO 2 (oxygen partial pressure) values; O2 consumption rates were 0.63 and 1.12 μ mol g-1 wet wt h-1 at 2.5° and 8°C, respectively; such rates were comparable to those previously measured for other pogonophorans. Intact specimens of R. pachyptila (including bacterial symbionts) did not consume significant amounts of CH4 from the environment. The respiratory quotients, in the absence of added sulfide, indicated that metabolism was mainly heterotrophic. High rates of uptake of dissolved amino acids were recorded for one specimen. The total [CO2] in the vascular blood and the Hb-containing coelomic fluid were high. Under anaerobic conditions, there were equilibrium distributions of pH, total [CO2] and sulfide concentrations between the vascular blood and the coelomic fluid, apparently because these metabolites were readily exchanged between the two compartments. The vascular blood bound neither CH4 nor H2. However, sulfide was reversibly bound by both the vascular blood and coelomic fluid; because this binding depended strongly on pH (with a maximum at about 7.5), HS- was probably the molecular species bound. Under anaerobic, but not aerobic conditions, the trophosome bound substantial amount of sulfide; thus, the high concentrations of sulfide in the trophosome may have resulted mainly from sulfide bound to sulfide oxidases under anaerobic conditions. The coelomic fluid had a relatively low buffering capacity (2.2 mmol CO2ΔpH-1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394718
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  • 2
    Electronic Resource
    Electronic Resource
    The importance of methane and thiosulfate in the metabolism of the bacterial symbionts of two deep-sea mussels (1987)
    Springer
    Marine biology 96 (1987), S. 59-71 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Undescribed hydrocarbon-seep mussels were collected from the Louisiana Slope, Gulf of Mexico, during March 1986, and the ultrastructure of their gills was examined and compared to Bathymodiolus thermophilus, a mussel collected from the deep-sea hydrothermal vents on the Galápagos Rift in March 1985. These closely related mytilids both contain abundant symbiotic bacteria in their gills. However, the bacteria from the two species are distinctly different in both morphology and biochemistry, and are housed differently within the gills of the two mussels. The symbionts from the seep mussel are larger than the symbionts from B. thermophilus and, unlike the latter, contain stacked intracytoplasmic membranes. In the seep mussel three or fewer symbionts appear to be contained in each host-cell vacuole, while in B. thermophilus there are often more than twenty bacteria visible in a single section through a vacuole. The methanotrophic nature of the seep-mussel symbionts was confirmed in 14C-methane uptake experiments by the appearance of label in both CO2 and acid-stable, non-volatile, organic compounds after a 3 h incubation of isolated gill tissue. Furthermore, methane consumption was correlated with methanol dehydrogenase activity in isolated gill tissue. Activity of ribulose-1,5-biphosphate (RuBP) carboxylase and 14CO2 assimilation studies indicate the presence of either a second type of symbiont or contaminating bacteria on the gills of freshly captured seep mussels. A reevaluation of the nutrition of the symbionts in B. thermophilus indicates that while the major symbiont is not a methanotroph, its status as a sulfur-oxidizing chemoautotroph, as has been suggested previously, is far from proven.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394838
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  • 3
    Electronic Resource
    Electronic Resource
    Translocation of fixed carbon from symbiotic bacteria to host tissues in the gutless bivalve Solemya reidi (1986)
    Springer
    Marine biology 93 (1986), S. 59-68 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solemya reidii (Bernard, 1980) were collected by Van Veen grab near a sewage outfall in California, USA, in spring/early summer of 1984 and 1985. Fixation of carbon dioxide by symbiotic chemoautotrophic bacteria in the gills, followed by translocation of the fixed carbon to symbiontfree tissues of the clam has been demonstrated using NaH14CO3 in two types of experiments. The first approach used the technique of tissue autoradiography to determine the exact sites of fixation of carbon dioxide and subsequent utilization of the fixed carbon compounds. Initial deposition (〉95% after 10 min) was in the well defined portion of the gill filaments where the symbiotic bacteria reside. The heaviest redeposition of labeled carbon after a 2 d chase period was in the various glandular tissues of the clams (8 to 38% of the gill level). Levels in two of these glandular tissues decreased after a 5 d chase period, probably due to secretion. Significant labeling of muscle tissue, gonads, and the tips of the gill filaments occurred only after the chase periods. In the second approach, rates of initial carbon fixation by symbiotic bacteria and translocation into clam tissues were determined using pulse-chase experiments followed by dissections and assay of the clam tissues for radioactivity. Freshly caught clams fixed carbon at an average rate of 0.8 μmol CO2 g-1 wet weight h-1. In these fresh clams, 88% of the fixed carbon was found in the gills after 2 min incubation periods, with only 44% remaining in the gills after 1 to 1.7 h incubations. Individuals maintained in the laboratory for 100 d had only 5.8% of the RuBP carboxylase (a diagnostic enzyme for autotrophs) activity in their gills compared to freshly caught clams. After 2 min incubations in NaH14CO3, only 21% of the carbon fixed by the “old” clams was found in their gills, and the rate of incoporation into gill tissue was 5.7% of the rate in fresh individuals. These experiments demonstrate that the symbiotic bacteria fix carbon at a high rate, that a significant portion of the carbon fixed by the symbiotic bacteria (〉45%) is translocated to the host, and that the translocated carbon is used by the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428655
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  • 4
    Electronic Resource
    Electronic Resource
    Tubeworm succession at hydrothermal vents: use of biogenic cues to reduce habitat selection error? (2000)
    Springer
    Oecologia 123 (2000), S. 275-284 
    Details
    ISSN: 1432-1939
    Keywords: Key words Deep-sea ecology ; Hydrothermal vent ; Riftia pachyptila ; Succession ; Tevnia jerichonana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Species colonizing new deep-sea hydrothermal vents along the East Pacific Rise show a distinct successional sequence: pioneer assemblages dominated by the vestimentiferan tubeworm Tevnia jerichonana being subsequently invaded by another vestimentiferan Riftia pachyptila, and eventually the mussel Bathymodiolus thermophilus. Using a manipulative approach modified from shallow-water ecological studies, we test three alternative hypotheses to explain the initial colonization by T. jerichonana and its subsequent replacement by R. pachyptila. We show that R. pachyptila and another vestimentiferan, Oasisia alvinae, colonized new surfaces only if the surfaces also were colonized by T. jerichonana. This pattern does not appear to be due to restricted habitat tolerances or inferior dispersal capabilities of R. pachyptila and O. alvinae, and we argue the alternative explanation that T. jerichonana facilitates the settlement of the other two species and is eventually outcompeted by R. pachyptila. Unlike the classic model of community succession, in which facilitating species promote their own demise by modifying the environment to make it more hospitable for competitors, we suggest that T. jerichonana may produce a chemical substance that induces settlement of these competitors. This process of selecting habitat based on biogenic cues may be especially adaptive and widespread among later-successional species that occupy a physically variable and unpredictable environment. In these cases, the presence of weedy species implies some integrated period of environmental suitability, whereas an instantaneous assessment of physical habitat conditions, such as water temperature for vent tubeworms, provides a poorer predictor of long-term habitat suitability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420051014
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  • 5
    Electronic Resource
    Electronic Resource
    Methanotrophic symbiont location and fate of carbon incorporated from methane in a hydrocarbon seep mussel (1997)
    Springer
    Marine biology 129 (1997), S. 465-476 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seep Mytilid Ia (SMIa), an undescribed mussel found at hydrocarbon seeps in the Gulf of Mexico, harbors intracellular methanotrophic symbionts. Two techniques were used to address the hypothesis that host digestion of symbionts is a significant mechanism of carbon transfer from symbiont to host in the SMIa association: lysosomal enzyme cytochemistry and 14C tissue autoradiography. Acid phosphatase activity was consistently localized in the Golgi apparatus and associated vesicles of gill cells, but was detected around bacteria in only three of approximately 50 bacteriocytes examined. These results indicate that the cellular equipment necessary for lysosomal digestion of symbionts is present in host bacteriocytes, but that acid phosphatase activity in symbiont vacuoles is rare at a given point in time. Tissue autoradiography was conducted with mussels collected in September 1992 to document carbon fixation by symbionts and follow the time course of transfer to host tissues. No asymbiotic host cell type showed a significant increase in relative grain density until at least 1 d after the end of incubation with 14C-methane. The ratio of label in the basal portion of bacteriocytes to total bacteriocyte label did not show a significant increase until 10 d after the end of the incubation period, indicating a slow increase of labeled carbon in the putative residual bodies, containing the remnants of lysosomal digestion. These results are consistent with the hypothesis that host digestion of symbionts is one route of nutrient acquisition in SMIa. Intracellular methanotrophic bacteria were found outside of the gill in SMIa juveniles, in mantle and foot epithelial tissues previously believed to be symbiont-free. These extra-gill symbionts and their host cells are morphologically similar to their gill counterparts and, like the gill symbionts, actively fix carbon from methane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050187
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  • 6
    Electronic Resource
    Electronic Resource
    Composition of free amino acids and related compounds in invertebrates with symbiotic bacteria at hydrocarbon seeps in the Gulf of Mexico (2000)
    Springer
    Marine biology 136 (2000), S. 411-420 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five species of bivalves and two species of vestimentiferan tubeworms were collected from hydrocarbon seeps in the Gulf of Mexico, and the composition of their free amino acid and related compounds analysed. Like other marine molluscs, taurine, glycine, glutamic acid, and alanine were abundant in the seep bivalves, but, unlike other molluscs, hypotaurine and thiotaurine were also abundant in the seep species. The relative levels of the most abundant amino compounds indicate that glycine is likely to be an important osmoregulatory compound in the bivalves, but not in the vestimentiferans. A consistent pattern of decreasing taurine:glycine ratio with increasing depth was evident in both vent and seep bivalves, and attributed to differences in the relative availability of taurine and glycine in their diet. Additionally, the generally high glutamate levels and higher levels in the symbiont-containing gills are interpreted as consistent with the proposed role of glutamate as a nutritive transfer molecule in these symbioses. The distribution of hypotaurine and thiotaurine in the seep species is discussed in relation to previously proposed hypotheses on the function of these compounds: hypotaurine as an antioxidant, and thiotaurine as a binding and transport molecule for reduced-sulphur species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050700
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  • 7
    Electronic Resource
    Electronic Resource
    Role of filter-feeding in the nutritional biology of a deep-sea mussel with methanotrophic symbionts (1990)
    Springer
    Marine biology 104 (1990), S. 251-257 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ability of an undescribed deep-sea hydrocarbon-seep mussel which contains endosymbiotic methanotrophic bacteria to clear, ingest, and assimilate radiolabeled bacteria (Vibrio pelagicus andEscherichia coli) and algae (Dunaliella tertiolecta) was compared with that of the bay musselMytilus edulis. The seep mussel, collected in August 1987 from the Louisana Slope in the Gulf of Mexico, was slower to clear bacteria and algae thanM. edulis. The ingestion and assimilation of filtered bacteria and algae was established from the presence of radiolabel in mussel tissues and feces. The seep mussel was somewhat less efficient in assimilating radiolabeled components from bacteria and algae thanM. edulis. The dietary carbon maintenance-requirement of the seep mussel could potentially be met at environmental concentrations of greater than 106 bacteria ml−1. At lower concentrations of particulate organic matter, filter-feeding could be an important source of nitrogen and essential nutrients not supplied by the endosymbionts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313266
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  • 8
    Electronic Resource
    Electronic Resource
    The methane mussel: roles of symbiont and host in the metabolic utilization of methane (1992)
    Springer
    Marine biology 112 (1992), S. 389-401 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methane mussels (Bathymodiolus sp., undescribed; personal communication by R. Turner to CRF) were collected in September 1989 and April 1990 from offshore Louisiana in the Gulf of Mexico. These mussels contain endosymbiotic methane-oxidizing bacteria and are capable of utilizing environmental methane as a source of energy and carbon. Oxygen consumption, methane consumption, and carbon dioxide production were measured in mussels with intact symbionts, functionally aposymbiotic mussels, and separated symbiont preparations under controlled oxygen and methane conditions, in order to study the roles of the symbionts and the hosts in methane utilization. The association was found to be very efficient in fixing methane carbon (only ∼30% of CH4 consumed is released as CO2), and to be capable of maximal rates of net carbon uptake of nearly 5 μmol g-1 h-1. Rates of oxygen and methane consumption were dependent upon oxygen and methane concentrations. Maximal consumption rates were measured at 250 to 300 μM O2 and 200 to 300 μM CH4, under which conditions, oxygen consumption by the gill tissues (containing symbionts) had increased more than 50-fold over rates measured in the absence of methane. A model is proposed for the functioning of the intact association in situ, which shows the symbiosis to be capable of achieving growth rates (net carbon assimilation) in the range of 0.003 to 0.50% per day depending upon oxygen and methane concentrations. Under the conditions measured in the seep environment (200 μM O2, 60 μM CH4), a mussel consuming methane at rates found to be typical (4 to 5 μmol g-1 h-1) should have a net carbon assimilation rate of about 0.1% per day. We suggest that the effectiveness of this symbiosis arises through integration of the morphological and physiological characteristics inherent to each of the symbiotic partners, rather than from extensive specialization exhibited by other deep-sea chemotrophic associations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00356284
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  • 9
    Electronic Resource
    Electronic Resource
    An autoradiographic examination of carbon fixation, transfer and utilization in the Riftia pachyptila symbiosis (2000)
    Springer
    Marine biology 136 (2000), S. 621-632 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Riftia pachyptila, the giant vestimentiferan tubeworm from the East Pacific Rise, harbors abundant chemolithoautotrophic, sulfide-oxidizing bacteria in an internal organ, the trophosome. Several facts, such as the lack of a digestive system in the host, stable carbon isotope values and net carbon dioxide uptake all suggest that the tubeworms obtain the bulk of their nutrition from their symbionts. Using tissue autoradiography, we investigated the mode of nutritional transfer between symbionts and host, and the site of early incorporation of symbiont fixed-carbon in the host. Fast labeling in the trophosome clearly demonstrates that the symbionts are the primary site of carbon fixation. Appearance of label in some symbiont-free host tissues in as little as 15 min indicates that the symbionts release a significant amount of organic carbon immediately after fixation. The organic carbon is largely incorporated into specific, metabolically active host tissues such as fast-growing body regions in the trunk and plume, and into tube-secreting glands. In addition to immediate release of fixed carbon by the symbionts, there is evidence of a second possible nutritional mode, digestion of the symbionts, which is consistent with previous suggestions based on trophosome ultrastructure. Results suggest that symbiont-containing host cells migrate in a predictable pattern within trophosome lobules and that symbiont division occurs predominately in the center of a lobule, followed eventually by autolysis/digestion at the periphery of the lobule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050722
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  • 10
    Electronic Resource
    Electronic Resource
    Ammonium and free amino acid uptake by a deep-sea mussel (Bathymodiolus sp., undescribed) containing methanotrophic bacterial symbionts (1992)
    Springer
    Marine biology 113 (1992), S. 99-106 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mussels (Bathymodiolus sp., undescribed) that contain endosymbiotic methanotrophic bacteria were collected from the vicinity of hydrocarbon seeps on the Louisiana Slope of the Gulf of Mexico during September 1989 and 1991. In the presence of methane, these mussels took up ammonium and free amino acids (FAA) but not nitrate. Rates of ammonium uptake ranged from 0.11 to 0.78 μmolg-1 h-1 following initial concentrations of 3.7 to 140.0 μM. The relationship between uptake rate and ammonium concentration exhibited by these mussels appears to be non-linear, apparently differing from the linear kinetics exhibited by algal-invertebrate symbioses. Alanine and glycine were depleted from the medium by symbiotic mussels at rates of 0.10 and 0.07 μmolg-1 h-1 following initial concentrations of 1 μM. Given estimates of rates of carbon fixation and ammonium and FAA levels encountered by the mussels in situ, it is likely that ammonium uptake can meet the nitrogen needs of the association, and that acquisition of carbon and nitrogen from FAA uptake may be an important supplement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367643
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