The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
François H. Lallier - One of the best experts on this subject based on the ideXlab platform.
-
Identification, sequencing, and localization of a new carbonic anhydrase transcript from the hydrothermal vent tubeworm Riftia Pachyptila
The FEBS journal, 2007Co-Authors: Sophie Sanchez, Ann C Andersen, Stephane Hourdez, François H. LallierAbstract:The vestimentiferan annelid Riftia Pachyptila forms dense populations at hydrothermal vents along the East Pacific Rise at a depth of 2600 m. It harbors CO2-assimilating sulfide-oxidizing bacteria that provide all of its nutrition. To find specific host transcripts that could be important for the functioning of this symbiosis, we used a subtractive suppression hybridization approach to identify plume- or trophosome-specific proteins. We demonstrated the existence of carbonic anhydrase transcripts, a protein endowed with an essential role in generating the influx of CO2 required by the symbionts. One of the transcripts was previously known and sequenced. Our quantification analyses showed a higher expression of this transcript in the trophosome compared to the branchial plume or the body wall. A second transcript, with 69.7% nucleotide identity compared to the previous one, was almost only expressed in the branchial plume. Fluorescent in situ hybridization confirmed the coexpression of the two transcripts in the branchial plume in contrast with the trophosome where only one transcript could be detected. An alignment of these translated carbonic anhydrase cDNAs with vertebrate and nonvertebrate carbonic anhydrase protein sequences revealed the conservation of most amino acids involved in the catalytic site. According to the phylogenetic analyses, the two R. Pachyptila transcripts clustered together but not all nonvertebrate sequences grouped together. Complete sequencing of the new carbonic anhydrase transcript revealed the existence of two slightly divergent isoforms probably coded by two different genes.
-
biometry of the branchial plume in the hydrothermal vent tubeworm riftia Pachyptila vestimentifera annelida
Canadian Journal of Zoology, 2002Co-Authors: Ann C Andersen, Sylvie Jolivet, Stephanie Claudinot, François H. LallierAbstract:The branchial plume of the hydrothermal vent tubeworm Riftia Pachyptila is the main organ by which this mouth- and gut-less tubeworm directly exchanges metabolites with its environment. We estimated the total branchial surface area per unit wet mass, termed the specific branchial surface area (SBSA), from planimetric measurements. Changes in the SBSA during the growth of the worm were inferred from 16 individuals ranging from 1 to 112 g wet mass. Riftia Pachyptila has a mean SBSA of 22 cm2·g1, the second highest among all aquatic animals, representing 9 times the surface area of the rest of the body. Three significantly different classes of SBSA could be distinguished, corresponding to small, medium-sized, and large individuals. The SBSA values for small and medium-sized R. Pachyptila are twice that for large individuals. Negative growth allometry between the length of the branchial plume and that of the trunk may be correlated with this variation in SBSA, the plume growing faster than the trunk in the s...
-
Biometry of the branchial plume in the hydrothermal vent tubeworm Riftia Pachyptila (Vestimentifera; Annelida)
Canadian Journal of Zoology, 2002Co-Authors: Ann C Andersen, Sylvie Jolivet, Stephanie Claudinot, François H. LallierAbstract:The branchial plume of the hydrothermal vent tubeworm Riftia Pachyptila is the main organ by which this mouth- and gut-less tubeworm directly exchanges metabolites with its environment. We estimated the total branchial surface area per unit wet mass, termed the specific branchial surface area (SBSA), from planimetric measurements. Changes in the SBSA during the growth of the worm were inferred from 16 individuals ranging from 1 to 112 g wet mass. Riftia Pachyptila has a mean SBSA of 22 cm2·g1, the second highest among all aquatic animals, representing 9 times the surface area of the rest of the body. Three significantly different classes of SBSA could be distinguished, corresponding to small, medium-sized, and large individuals. The SBSA values for small and medium-sized R. Pachyptila are twice that for large individuals. Negative growth allometry between the length of the branchial plume and that of the trunk may be correlated with this variation in SBSA, the plume growing faster than the trunk in the small and medium-sized groups. In large individuals the trunk length exceeds the plume length, inducing an increase in body mass that lowers the SBSA. However, a lower SBSA does not imply reduced metabolite diffusion through the plume of large tubeworms, since their longer free filaments bear more developed pinnules, which are probably the preferred pathway of metabolite diffusion, owing to a minimal transepithelial distance of 2 µm.
-
Nitrogen metabolites and related enzymatic activities in the body fluids and tissues of the hydrothermal vent tubeworm Riftia Pachyptila.
The Journal of Experimental Biology, 2000Co-Authors: M. De Cian, M. Regnault, François H. LallierAbstract:The distribution of nitrogen metabolism end-products and the associated enzyme activities, free amino acids and purine base catabolites were investigated in all the body compartments (circulating fluids and tissues) of the hydrothermal vent tubeworm Riftia Pachyptila to acquire a general overview of nitrogen metabolism in this symbiotic organism. There were striking differences between the symbiont-containing trophosome tissue and other host tissues. High concentrations of ammonia, creatinine and, in particular, urate were found in all tissues, but they were present at consistently higher concentrations in the trophosome, which also contained large amounts of urea. Uric acid crystals were present at the periphery of trophosome lobules. The urea cycle appears to be fully functional in this tissue, which also uses creatine phosphate for phosphagen storage, while arginine phosphate or a combination of both phosphagens occurs in other tissues. The amino acid patterns are dominated by sulphated compounds in all tissues except the trophosome, which has high levels of aspartate and glutamate. Although no definitive conclusions could be drawn regarding the nitrogen regime of Riftia Pachyptila, this in vitro study gives several indications for future research in this area.
-
the ionic composition of the hydrothermal vent tube worm riftia Pachyptila evidence for the elimination of so2 4so and h and for a cl hco 3hco shift
Physiological and Biochemical Zoology, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Abstract Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss}...
Horst Felbeck - One of the best experts on this subject based on the ideXlab platform.
-
Host-Microbe Interactions in the Chemosynthetic Riftia Pachyptila Symbiosis.
mBio, 2019Co-Authors: Tjorven Hinzke, Manuel Kleiner, Corinna Breusing, Horst Felbeck, Robert Häsler, Stefan M. Sievert, Rabea Schlüter, Philip Rosenstiel, Thorsten B.h. Reusch, Thomas SchwederAbstract:The deep-sea tubeworm Riftia Pachyptila lacks a digestive system but completely relies on bacterial endosymbionts for nutrition. Although the symbiont has been studied in detail on the molecular level, such analyses were unavailable for the animal host, because sequence information was lacking. To identify host-symbiont interaction mechanisms, we therefore sequenced the Riftia transcriptome, which served as a basis for comparative metaproteomic analyses of symbiont-containing versus symbiont-free tissues, both under energy-rich and energy-limited conditions. Our results suggest that metabolic interactions include nutrient allocation from symbiont to host by symbiont digestion and substrate transfer to the symbiont by abundant host proteins. We furthermore propose that Riftia maintains its symbiont by protecting the bacteria from oxidative damage while also exerting symbiont population control. Eukaryote-like symbiont proteins might facilitate intracellular symbiont persistence. Energy limitation apparently leads to reduced symbiont biomass and increased symbiont digestion. Our study provides unprecedented insights into host-microbe interactions that shape this highly efficient symbiosis.IMPORTANCE All animals are associated with microorganisms; hence, host-microbe interactions are of fundamental importance for life on earth. However, we know little about the molecular basis of these interactions. Therefore, we studied the deep-sea Riftia Pachyptila symbiosis, a model association in which the tubeworm host is associated with only one phylotype of endosymbiotic bacteria and completely depends on this sulfur-oxidizing symbiont for nutrition. Using a metaproteomics approach, we identified both metabolic interaction processes, such as substrate transfer between the two partners, and interactions that serve to maintain the symbiotic balance, e.g., host efforts to control the symbiont population or symbiont strategies to modulate these host efforts. We suggest that these interactions are essential principles of mutualistic animal-microbe associations.
-
Host-microbe interactions in the chemosynthetic Riftia Pachyptila symbiosis
2019Co-Authors: Tjorven Hinzke, Manuel Kleiner, Corinna Breusing, Horst Felbeck, Robert Häsler, Stefan M. Sievert, Rabea Schlüter, Philip Rosenstiel, Thorsten B.h. Reusch, Thomas SchwederAbstract:The deep-sea tubeworm Riftia Pachyptila lacks a digestive system, but completely relies on bacterial endosymbionts for nutrition. Although the symbiont has been studied in detail on the molecular level, such analyses were unavailable for the animal host, because sequence information was lacking. To identify host-symbiont interaction mechanisms, we therefore sequenced the Riftia transcriptome, which enabled comparative metaproteomic analyses of symbiont-containing versus symbiont-free tissues, both under energy-rich and energy-limited conditions. We demonstrate that metabolic interactions include nutrient allocation from symbiont to host by symbiont digestion, and substrate transfer to the symbiont by abundant host proteins. Our analysis further suggests that Riftia maintains its symbiont by protecting the bacteria from oxidative damage, while also exerting symbiont population control. Eukaryote-like symbiont proteins might facilitate intracellular symbiont persistence. Energy limitation apparently leads to reduced symbiont biomass and increased symbiont digestion. Our study provides unprecedented insights into host-microbe interactions that shape this highly efficient symbiosis.
-
metabolic versatility of the riftia Pachyptila endosymbiont revealed through metagenomics
Environmental Microbiology, 2008Co-Authors: Julie Robidart, Shellie R Bench, Robert A Feldman, Alexey Novoradovsky, Sheila Podell, Terry Gaasterland, Eric E Allen, Horst FelbeckAbstract:The facultative symbiont of Riftia Pachyptila, named here Candidatus Endoriftia persephone, has evaded culture to date, but much has been learned regarding this symbiosis over the past three decades since its discovery. The symbiont population metagenome was sequenced in order to gain insight into its physiology. The population genome indicates that the symbionts use a partial Calvin–Benson Cycle for carbon fixation and the reverse TCA cycle (an alternative pathway for carbon fixation) that contains an unusual ATP citrate lyase. The presence of all genes necessary for heterotrophic metabolism, a phosphotransferase system, and dicarboxylate and ABC transporters indicate that the symbiont can live mixotrophically. The metagenome has a large suite of signal transduction, defence (both biological and environmental) and chemotaxis mechanisms. The physiology of Candidatus Endoriftia persephone is explored with respect to functionality while associated with a eukaryotic host, versus free-living in the hydrothermal environment.
-
physiological proteomics of the uncultured endosymbiont of riftia Pachyptila
Science, 2007Co-Authors: Stephanie Markert, Horst Felbeck, Stefan M. Sievert, Julie Robidart, Cordelia Arndt, Dorte Becher, Michael Hugler, Dirk Albrecht, Shellie R Bench, Robert A FeldmanAbstract:The bacterial endosymbiont of the deep-sea tube worm Riftia Pachyptila has never been successfully cultivated outside its host. In the absence of cultivation data, we have taken a proteomic approach based on the metagenome sequence to study the metabolism of this peculiar microorganism in detail. As one result, we found that three major sulfide oxidation proteins constitute ∼12% of the total cytosolic proteome, which highlights the essential role of these enzymes for the symbiont's energy metabolism. Unexpectedly, the symbiont uses the reductive tricarboxylic acid cycle in addition to the previously identified Calvin cycle for CO2 fixation.
-
proposed nitrate binding by hemoglobin in riftia Pachyptila blood
Deep Sea Research Part I: Oceanographic Research Papers, 2005Co-Authors: Edda Hahlbeck, James J. Childress, Franck Zal, Mark A. Pospesel, Horst FelbeckAbstract:Riftia Pachyptila lives in the unstable environment at hydrothermal vent sites along oceanic spreading zones in the Eastern Pacific. The tubeworm has a symbiosis with intracellular carbon-fixing and sulfide-oxidizing bacteria. Nitrate is the main source of nitrogen available from their habitat. This compound serves as a substrate either for nitrate respiration or for biosynthesis after transformation into ammonia. Very high nitrate (up to 3.2 mM) and nitrite (up to 0.8 mM) concentrations in vascular blood of R. Pachyptila indicate a novel uptake mechanism. The dialysis experiments reported here demonstrate the binding and transport of nitrate to the symbionts by high molecular weight components in the blood, most likely hemoglobin. The extent to which nitrate is bound differed markedly between blood from different animals. In addition, a strong inverse correlation was found between the concentrations of sulfide and nitrate in vascular blood, as well as between the sulfur content of trophosome and the nitrate content of vascular blood. Specimens with low sulfur stores showed much lower nitrate levels than those with pale green trophosome due to high levels of elemental sulfur.
James J. Childress - One of the best experts on this subject based on the ideXlab platform.
-
proposed nitrate binding by hemoglobin in riftia Pachyptila blood
Deep Sea Research Part I: Oceanographic Research Papers, 2005Co-Authors: Edda Hahlbeck, James J. Childress, Franck Zal, Mark A. Pospesel, Horst FelbeckAbstract:Riftia Pachyptila lives in the unstable environment at hydrothermal vent sites along oceanic spreading zones in the Eastern Pacific. The tubeworm has a symbiosis with intracellular carbon-fixing and sulfide-oxidizing bacteria. Nitrate is the main source of nitrogen available from their habitat. This compound serves as a substrate either for nitrate respiration or for biosynthesis after transformation into ammonia. Very high nitrate (up to 3.2 mM) and nitrite (up to 0.8 mM) concentrations in vascular blood of R. Pachyptila indicate a novel uptake mechanism. The dialysis experiments reported here demonstrate the binding and transport of nitrate to the symbionts by high molecular weight components in the blood, most likely hemoglobin. The extent to which nitrate is bound differed markedly between blood from different animals. In addition, a strong inverse correlation was found between the concentrations of sulfide and nitrate in vascular blood, as well as between the sulfur content of trophosome and the nitrate content of vascular blood. Specimens with low sulfur stores showed much lower nitrate levels than those with pale green trophosome due to high levels of elemental sulfur.
-
Experimental application of vascular and coelomic catheterization to identify vascular transport mechanisms for inorganic carbon in the vent tubeworm, Riftia Pachyptila
Deep Sea Research Part I: Oceanographic Research Papers, 2004Co-Authors: Horst Felbeck, Ute Hentschel, C. Arndt, James J. ChildressAbstract:Maintaining deep sea animals in in situ conditions has always been technically difficult because of the high-pressure requirements. Even more difficult are any attempts in manipulating or sampling these organisms while keeping them alive in high-pressure aquaria. We present a technique to withdraw blood samples by vascular catheterization which allows withdrawal of samples of during maintenance of specimens under high-pressure conditions. We have developed this technique to answer a long debated question, how carbon dioxide is transported from the ambient sea water to the bacterial symbionts inside the trophosome of the hydrothermal vent tubeworm Riftia Pachyptila. Our results indicate that the carbon supply to the symbionts is mainly through inorganic CO2 while its incorporation into malate and succinate may serve storage functions at periods of low CO2 availability in the environment.
-
activity and inhibitor sensitivity of atpases in the hydrothermal vent tubeworm riftia Pachyptila a comparative approach
Marine Biology, 2001Co-Authors: Shana K Goffredi, James J. ChildressAbstract:Phosphorylated ATPases may be involved in the effective pH regulation seen in the hydrothermal vent tubeworm Riftia Pachyptila. R. Pachyptila appears not only to have a large concentration of ATPases, but the main function of these ATPases seems to have shifted from other types of transport, such as Na+ and K+ movement, to the facilitation of H+ elimination. Plume and trophosome ATPase activity for R. Pachyptila measured 646.2 ± 29.5 and 481.4 ± 32.0 μmol Pi (inorganic phosphate) g−1 wet wt h−1, respectively. Plume tissue ATPase activity (both mass-specific and protein-specific) in R. Pachyptila was higher (between 7% and 55%) than the activity measured in any tissue for 7 other shallow- and deep-living species, in this study. This supports the hypothesis that R. Pachyptila regulates acid/base balance via high concentrations of H+-ATPases, including Na+/H+ and K+/H+ exchangers and possibly electrogenic H+-ATPases, as evidenced by a higher total ATPase concentration (646 μmol Pi g−1 wet wt h−1), lesser Na+/K+-ATPase activity (13% of the total, as compared to 20−40% found in other animals), and higher H+-ATPase activity (226–264 μmol Pi g−1wet wt h−1). Overall, R. Pachyptila appears to demonstrate elevated ATPase activity, with a greater fraction of the enzymes devoted to proton elimination, in order to effectively control its extracellular pH in the face of processes acting to acidify the internal environment.
-
Fate of nitrate acquired by the tubeworm Riftia Pachyptila.
Applied and environmental microbiology, 2000Co-Authors: Peter R Girguis, James J. Childress, Horst Felbeck, Nicole T. Desaulniers, Mark A. Pospesel, Raymond W. Lee, Franck ZalAbstract:The hydrothermal vent tubeworm Riftia Pachyptila lacks a mouth and gut and lives in association with intracellular, sulfide-oxidizing chemoautotrophic bacteria. Growth of this tubeworm requires an exogenous source of nitrogen for biosynthesis, and, as determined in previous studies, environmental ammonia and free amino acids appear to be unlikely sources of nitrogen. Nitrate, however, is present in situ (K. Johnson, J. Childress, R. Hessler, C. Sakamoto-Arnold, and C. Beehler, Deep-Sea Res. 35:1723–1744, 1988), is taken up by the host, and can be chemically reduced by the symbionts (U. Hentschel and H. Felbeck, Nature 366:338–340, 1993). Here we report that at an in situ concentration of 40 μM, nitrate is acquired by R. Pachyptila at a rate of 3.54 μmol g−1 h−1, while elimination of nitrite and elimination of ammonia occur at much lower rates (0.017 and 0.21 μmol g−1 h−1, respectively). We also observed reduction of nitrite (and accordingly nitrate) to ammonia in the trophosome tissue. When R. Pachyptila tubeworms are exposed to constant in situ conditions for 60 h, there is a difference between the amount of nitrogen acquired via nitrate uptake and the amount of nitrogen lost via nitrite and ammonia elimination, which indicates that there is a nitrogen “sink.” Our results demonstrate that storage of nitrate does not account for the observed stoichiometric differences in the amounts of nitrogen. Nitrate uptake was not correlated with sulfide or inorganic carbon flux, suggesting that nitrate is probably not an important oxidant in metabolism of the symbionts. Accordingly, we describe a nitrogen flux model for this association, in which the product of symbiont nitrate reduction, ammonia, is the primary source of nitrogen for the host and the symbionts and fulfills the association's nitrogen needs via incorporation of ammonia into amino acids.
-
the ionic composition of the hydrothermal vent tube worm riftia Pachyptila evidence for the elimination of so2 4so and h and for a cl hco 3hco shift
Physiological and Biochemical Zoology, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Abstract Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss}...
Shana K Goffredi - One of the best experts on this subject based on the ideXlab platform.
-
activity and inhibitor sensitivity of atpases in the hydrothermal vent tubeworm riftia Pachyptila a comparative approach
Marine Biology, 2001Co-Authors: Shana K Goffredi, James J. ChildressAbstract:Phosphorylated ATPases may be involved in the effective pH regulation seen in the hydrothermal vent tubeworm Riftia Pachyptila. R. Pachyptila appears not only to have a large concentration of ATPases, but the main function of these ATPases seems to have shifted from other types of transport, such as Na+ and K+ movement, to the facilitation of H+ elimination. Plume and trophosome ATPase activity for R. Pachyptila measured 646.2 ± 29.5 and 481.4 ± 32.0 μmol Pi (inorganic phosphate) g−1 wet wt h−1, respectively. Plume tissue ATPase activity (both mass-specific and protein-specific) in R. Pachyptila was higher (between 7% and 55%) than the activity measured in any tissue for 7 other shallow- and deep-living species, in this study. This supports the hypothesis that R. Pachyptila regulates acid/base balance via high concentrations of H+-ATPases, including Na+/H+ and K+/H+ exchangers and possibly electrogenic H+-ATPases, as evidenced by a higher total ATPase concentration (646 μmol Pi g−1 wet wt h−1), lesser Na+/K+-ATPase activity (13% of the total, as compared to 20−40% found in other animals), and higher H+-ATPase activity (226–264 μmol Pi g−1wet wt h−1). Overall, R. Pachyptila appears to demonstrate elevated ATPase activity, with a greater fraction of the enzymes devoted to proton elimination, in order to effectively control its extracellular pH in the face of processes acting to acidify the internal environment.
-
the ionic composition of the hydrothermal vent tube worm riftia Pachyptila evidence for the elimination of so2 4so and h and for a cl hco 3hco shift
Physiological and Biochemical Zoology, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Abstract Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss}...
-
The ionic composition of the hydrothermal vent tube worm Riftia Pachyptila: evidence for the elimination of SO2-4SO and H+ and for a Cl-/HCO-3HCO shift.
Physiological and biochemical zoology : PBZ, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a 1:1 stoichiometry. We believe this shift in chloride, out of the body fluids, is needed to compensate for changes in electrochemical balance caused by the large increase (up to and greater than 60 mmol L-1) in negatively charged bicarbonate. Riftia Pachyptila fits the general pattern of monovalent ion concentrations that is seen in other benthic marine invertebrates, with a high [Na+] : [K+] ratio extracellularly and low [Na+] : [K+] ratio intracellularly. Extracellular pH values of 7.38+/-0.03 and 7.37+/-0. 04 for coelomic fluid and vascular blood, respectively, as well as intracellular pH values of 7.37+/-0.04 and 7.04+/-0.05 for plume and trophosome tissue, respectively, were measured. On the basis of significant decreases in extracellular pH and, in some cases, Na+ and K+, in worms exposed to carbonyl cyanide m-chlorophenylhydrazone, sodium vanadate, and N-ethylmaleimide, we suggest that high concentrations of H+-ATPases, perhaps Na+/H+- or K+/H+-ATPases, are involved in H+ elimination in these animals.
-
Physiological Functioning of Carbonic Anhydrase in the Hydrothermal Vent Tubeworm Riftia Pachyptila
The Biological bulletin, 1999Co-Authors: Shana K Goffredi, James J. Childress, Peter R Girguis, Nicole T. DesaulniersAbstract:On the basis of our experiments, it is clear that carbonic anhydrase (CA) plays an important role in the CO,-concentrating mechanisms in Riftia Pachyptila. Plume tissue from freshly collected animals had the highest CA activity, 253.7 ? 36.0 pmol CO, mini g-' wet wt, and trophosome activity averaged 109.4 ? 17.9 pmol CO, min-l g-' wet wt. Exposure of living worms to ethoxyzol- amide, a carbonic anhydrase inhibitor, resulted in a 99% decrease in CA activity (from 103.9 ? 38.6 to 0.7 + 0.2 pmol CO, min-' g-' wet wt in the plume tissue and 57.6 -+ 17.9 to 0.04 2 0.11 pmol CO, min-' g-' wet wt in the trophosome) and essentially a complete cessation of CCO, uptake. High concentrations of CA appear to facilitate the equilibration between inorganic carbon (Ci) in the external and internal environments, greatly enhancing the diffusion of CO, into the animal. In summary, R. Pachyptila demon- strates very effective acquisition of inorganic carbon from the environment, thereby providing the symbionts with large amounts of CO,. This effective acquisition is made possible by three factors: extremely effective pH regulation, a large external pool of CO,, and, described in this paper, high levels of carbonic anhydrase.
-
Inorganic carbon acquisition by the hydrothermal vent tubeworm Riftia Pachyptila depends upon high external PCO2 and upon proton-equivalent ion transport by the worm
The Journal of Experimental Biology, 1997Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. Desaulniers, R. W. Lee, D. HammondAbstract:Riftia Pachyptila is the most conspicuous organism living at deep sea hydrothermal vents along the East Pacific Rise. To support its large size and high growth rates, this invertebrate relies exclusively upon internal chemosynthetic bacterial symbionts. The animal must supply inorganic carbon at high rates to the bacteria, which are far removed from the external medium. We found substantial differences in body fluid total inorganic carbon (CO2) both within and between vent sites when comparing freshly captured worms from a variety of places. However, the primary influence on body fluid CO2 was the chemical characteristics of the site from which the worms were collected. Studies on tubeworms, both freshly captured and maintained in captivity, demonstrate that the acquisition of inorganic carbon is apparently limited by the availability of CO2, as opposed to bicarbonate, and thus appears to be accomplished via diffusion of CO2 into the plume, rather than by mediated transport of bicarbonate. The greatly elevated PCO2 measured at the vent sites (up to 12.6 kPa around the tubeworms), which is a result of low environmental pH (as low as 5.6 around the tubeworms), and elevated CO2 (as high as 7.1 mmol l-1 around the tubes) speeds this diffusion. Moreover, despite large and variable amounts of internal CO2, these worms maintain their extracellular fluid pH stable, and alkaline, in comparison with the environment. The maintenance of this alkaline pH acts to concentrate inorganic carbon into extracellular fluids. Exposure to N-ethylmaleimide, a non-specific H+-ATPase inhibitor, appeared to stop this process, resulting in a decline in extracellular pH and CO2. We hypothesize that the worms maintain their extracellular pH by active proton-equivalent ion transport via high concentrations of H+-ATPases. Thus, Riftia Pachyptila is able to support its symbionts' large demand for inorganic carbon owing to the elevated PCO2 in the vent environment and because of its ability to control its extracellular pH in the presence of large inward CO2 fluxes.
Nicole T. Desaulniers - One of the best experts on this subject based on the ideXlab platform.
-
Fate of nitrate acquired by the tubeworm Riftia Pachyptila.
Applied and environmental microbiology, 2000Co-Authors: Peter R Girguis, James J. Childress, Horst Felbeck, Nicole T. Desaulniers, Mark A. Pospesel, Raymond W. Lee, Franck ZalAbstract:The hydrothermal vent tubeworm Riftia Pachyptila lacks a mouth and gut and lives in association with intracellular, sulfide-oxidizing chemoautotrophic bacteria. Growth of this tubeworm requires an exogenous source of nitrogen for biosynthesis, and, as determined in previous studies, environmental ammonia and free amino acids appear to be unlikely sources of nitrogen. Nitrate, however, is present in situ (K. Johnson, J. Childress, R. Hessler, C. Sakamoto-Arnold, and C. Beehler, Deep-Sea Res. 35:1723–1744, 1988), is taken up by the host, and can be chemically reduced by the symbionts (U. Hentschel and H. Felbeck, Nature 366:338–340, 1993). Here we report that at an in situ concentration of 40 μM, nitrate is acquired by R. Pachyptila at a rate of 3.54 μmol g−1 h−1, while elimination of nitrite and elimination of ammonia occur at much lower rates (0.017 and 0.21 μmol g−1 h−1, respectively). We also observed reduction of nitrite (and accordingly nitrate) to ammonia in the trophosome tissue. When R. Pachyptila tubeworms are exposed to constant in situ conditions for 60 h, there is a difference between the amount of nitrogen acquired via nitrate uptake and the amount of nitrogen lost via nitrite and ammonia elimination, which indicates that there is a nitrogen “sink.” Our results demonstrate that storage of nitrate does not account for the observed stoichiometric differences in the amounts of nitrogen. Nitrate uptake was not correlated with sulfide or inorganic carbon flux, suggesting that nitrate is probably not an important oxidant in metabolism of the symbionts. Accordingly, we describe a nitrogen flux model for this association, in which the product of symbiont nitrate reduction, ammonia, is the primary source of nitrogen for the host and the symbionts and fulfills the association's nitrogen needs via incorporation of ammonia into amino acids.
-
the ionic composition of the hydrothermal vent tube worm riftia Pachyptila evidence for the elimination of so2 4so and h and for a cl hco 3hco shift
Physiological and Biochemical Zoology, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Abstract Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss}...
-
The ionic composition of the hydrothermal vent tube worm Riftia Pachyptila: evidence for the elimination of SO2-4SO and H+ and for a Cl-/HCO-3HCO shift.
Physiological and biochemical zoology : PBZ, 1999Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. DesaulniersAbstract:Riftia Pachyptila is one of the most specialized invertebrate hosts of chemoautotrophic symbionts. Crucial to the functioning of this symbiosis is how these worms cope with fluctuating ion concentrations. Internal sulfate levels in R. Pachyptila appear comparable with other benthic marine invertebrates, despite the production of sulfate internally by means of the bacterial oxidation of hydrogen sulfide, suggesting that these worms are able to eliminate sulfate effectively. Internal chloride levels appear comparable; however, coelomic fluid chloride levels decrease significantly as the amount of coelomic fluid bicarbonate increases, demonstrating a 1:1 stoichiometry. We believe this shift in chloride, out of the body fluids, is needed to compensate for changes in electrochemical balance caused by the large increase (up to and greater than 60 mmol L-1) in negatively charged bicarbonate. Riftia Pachyptila fits the general pattern of monovalent ion concentrations that is seen in other benthic marine invertebrates, with a high [Na+] : [K+] ratio extracellularly and low [Na+] : [K+] ratio intracellularly. Extracellular pH values of 7.38+/-0.03 and 7.37+/-0. 04 for coelomic fluid and vascular blood, respectively, as well as intracellular pH values of 7.37+/-0.04 and 7.04+/-0.05 for plume and trophosome tissue, respectively, were measured. On the basis of significant decreases in extracellular pH and, in some cases, Na+ and K+, in worms exposed to carbonyl cyanide m-chlorophenylhydrazone, sodium vanadate, and N-ethylmaleimide, we suggest that high concentrations of H+-ATPases, perhaps Na+/H+- or K+/H+-ATPases, are involved in H+ elimination in these animals.
-
Physiological Functioning of Carbonic Anhydrase in the Hydrothermal Vent Tubeworm Riftia Pachyptila
The Biological bulletin, 1999Co-Authors: Shana K Goffredi, James J. Childress, Peter R Girguis, Nicole T. DesaulniersAbstract:On the basis of our experiments, it is clear that carbonic anhydrase (CA) plays an important role in the CO,-concentrating mechanisms in Riftia Pachyptila. Plume tissue from freshly collected animals had the highest CA activity, 253.7 ? 36.0 pmol CO, mini g-' wet wt, and trophosome activity averaged 109.4 ? 17.9 pmol CO, min-l g-' wet wt. Exposure of living worms to ethoxyzol- amide, a carbonic anhydrase inhibitor, resulted in a 99% decrease in CA activity (from 103.9 ? 38.6 to 0.7 + 0.2 pmol CO, min-' g-' wet wt in the plume tissue and 57.6 -+ 17.9 to 0.04 2 0.11 pmol CO, min-' g-' wet wt in the trophosome) and essentially a complete cessation of CCO, uptake. High concentrations of CA appear to facilitate the equilibration between inorganic carbon (Ci) in the external and internal environments, greatly enhancing the diffusion of CO, into the animal. In summary, R. Pachyptila demon- strates very effective acquisition of inorganic carbon from the environment, thereby providing the symbionts with large amounts of CO,. This effective acquisition is made possible by three factors: extremely effective pH regulation, a large external pool of CO,, and, described in this paper, high levels of carbonic anhydrase.
-
Inorganic carbon acquisition by the hydrothermal vent tubeworm Riftia Pachyptila depends upon high external PCO2 and upon proton-equivalent ion transport by the worm
The Journal of Experimental Biology, 1997Co-Authors: Shana K Goffredi, James J. Childress, François H. Lallier, Nicole T. Desaulniers, R. W. Lee, D. HammondAbstract:Riftia Pachyptila is the most conspicuous organism living at deep sea hydrothermal vents along the East Pacific Rise. To support its large size and high growth rates, this invertebrate relies exclusively upon internal chemosynthetic bacterial symbionts. The animal must supply inorganic carbon at high rates to the bacteria, which are far removed from the external medium. We found substantial differences in body fluid total inorganic carbon (CO2) both within and between vent sites when comparing freshly captured worms from a variety of places. However, the primary influence on body fluid CO2 was the chemical characteristics of the site from which the worms were collected. Studies on tubeworms, both freshly captured and maintained in captivity, demonstrate that the acquisition of inorganic carbon is apparently limited by the availability of CO2, as opposed to bicarbonate, and thus appears to be accomplished via diffusion of CO2 into the plume, rather than by mediated transport of bicarbonate. The greatly elevated PCO2 measured at the vent sites (up to 12.6 kPa around the tubeworms), which is a result of low environmental pH (as low as 5.6 around the tubeworms), and elevated CO2 (as high as 7.1 mmol l-1 around the tubes) speeds this diffusion. Moreover, despite large and variable amounts of internal CO2, these worms maintain their extracellular fluid pH stable, and alkaline, in comparison with the environment. The maintenance of this alkaline pH acts to concentrate inorganic carbon into extracellular fluids. Exposure to N-ethylmaleimide, a non-specific H+-ATPase inhibitor, appeared to stop this process, resulting in a decline in extracellular pH and CO2. We hypothesize that the worms maintain their extracellular pH by active proton-equivalent ion transport via high concentrations of H+-ATPases. Thus, Riftia Pachyptila is able to support its symbionts' large demand for inorganic carbon owing to the elevated PCO2 in the vent environment and because of its ability to control its extracellular pH in the presence of large inward CO2 fluxes.
