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Joseph R Pawlik - One of the best experts on this subject based on the ideXlab platform.
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settlement of the gregarious Tube Worm hydroides dianthus polychaeta serpulidae i gregarious and nongregarious settlement
Marine Ecology Progress Series, 2001Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:We conducted still-water time-course experiments on cultured larvae of the serpulid polychaete Hydroides dianthus (Verrill, 1873) to examine timing and patterns of gregarious and non- gregarious settlement to better understand the conditions under which larvae of a gregarious species colonize new habitats. We first confirmed that these Worms are aggregated in the field, and quanti- fied patterns of association with a number of other common intertidal species. Patterns of negative association with spatial competitors is unlikely to have resulted from larval avoidance during settle- ment, because we found no difference in larval settlement in response to conspecifics with or without the solitary tunicate Ascidia interrupta present. We then examined the settlement of competent lar- vae in response to biofilm and conspecifics to determine the conditions under which the larvae of this gregarious species settle nongregariously. Larvae settled concurrently in response to both biofilm and conspecifics, starting approximately 4 d after fertilization, and response was of similar magnitude to both biofilm and to conspecifics for the first couple of days post-competency. While settlement in response to conspecifics continued in subsequent assays carried out over 70 d (at which time larvae began to die in culture), settlement in response to biofilm decreased abruptly after the peak, and ceased by Day 14. Settlement patterns were qualitatively similar regardless of previous exposure to substrata; similar results were obtained whether the whole population of larvae in culture was denied access to or daily provided access to 1 or both experimental substrata. Furthermore, these patterns of settlement did not change as larval planktonic period was prolonged. Of larvae settling during 24 h sample assays, the majority of larvae metamorphosed in response to biofilm during the first 6 h, whereas metamorphosis in the final 6 h (between 18 and 24 h) of the assays was primarily in response to conspecifics. These results are opposite to the pattern predicted by the desperate larva hypothesis, because some larvae settled in response to biofilm even after rejecting conspecifics the previous day. In fact, cultures of competent larvae appear to become more specific in terms of larval settlement in response to live adult conspecifics as the planktonic period is artificially prolonged.
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settlement of the gregarious Tube Worm hydroides dianthus polychaeta serpulidae ii testing the desperate larva hypothesis
Marine Ecology Progress Series, 2001Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:We have documented patterns of gregarious and nongregarious settlement among the larvae of the gregarious Tube Worm Hydroides dianthus (Verrill, 1873) and shown that larvae do not exhibit decreased substratum-specificity throughout a prolonged planktonic period regardless of prior exposure to experimental substrata. Previous investigations with barnacles and polychaetes have suggested that the colonization of new substrata occurs because larvae become less discrimi- nating as they age, i.e. that they become 'desperate' to settle after searching unsuccessfully for con- specifics for some period of time. This hypothesis, first proposed by Knight-Jones & Wilson, is based on an energetic model in which non-feeding (lecithotrophic) larvae continue to search for specific substrata as long as their energetic reserves allow, but begin to accept sub-optimal habitat rather than exhaust their reserves and die without metamorphosing. Here, we examined whether it is pos- sible to induce decreased substratum-specificity among competent larvae of the gregarious Tube Worm H. dianthus, which has feeding (planktotrophic) larvae. We show that neither altered feeding regimes nor larval starvation lead to decreased substratum-specificity among competent larvae; although larvae maintained at lower food concentrations take longer to reach competency, the qual- itative patterns of settlement on biofilm and conspecifics is unaltered by feeding regime. Further- more, starving competent larvae results in a loss of competency rather than larval desperation. Lar- vae belonging to different size classes ( 127 µm) showed similar patterns of settlement, and differences among sibling cultures with different mean larval sizes resulted from a decrease in the proportion of larvae settling in response to conspecifics rather than an increase in the proportion settling in response to biofilm. We examined a number of obvious life-his- tory characters for correlations with the tendency for larvae to settle nongregariously, and found that although a variety of life-history traits showed significant correlations, only the total number of eggs spawned by a dam was significantly correlated with the proportion of larvae settling in response to biofilm (r 2 = 0.19), and the slope of this relationship was negative. These results are again diametric to predictions of the desperate larva hypothesis, and indicate that larval desperation is unlikely to be a general explanation for the initiation of monospecific aggregations of fouling marine invertebrates.
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settlement of the Tube Worm hydroides dianthus polychaeta serpulidae cues for gregarious settlement
Marine Biology, 1996Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:The larvae of many benthic marine invertebrates settle to form conspecific aggregations and are thought to rely on chemical cues associated with adults as indicators of habitat suitability, although the identification of inductive compounds has proven difficult. Still-water laboratory assays carried out during the summers of 1992 and 1993 with larvae of the serpulid polychaete, Hydroides dianthus (Verrill, 1873), demonstrate that unidentified water-borne compound(s) were responsible for gregarious settlement of competent larvae. Unlike inductive compounds associated with other Tube-dwelling polychaetes, the settlement cue was soluble in water and was not associated with the Tube, but rather with the body of live adults. In assay chambers divided by a 52-μm mesh barrier, a greater percentage of larvae settled on biofilmed substrata when adult Worms were present on the other side of the barrier than when adults were absent. Settlement in response to conspecific adults, live Worms removed from their Tubes, and amputated tentacular crowns of live Worms was significantly greater than settlement in response to dead Worms, empty Tubes, or biofilmed slides. The settlement inducer appears to emanate from the openings of occupied Tubes; settlement was greatest along the anterior two-fifths of the Tube of living conspecific adults. A single adult was equally capable of eliciting a gregarious response as were five or 25 conspecifics, and newly settled juveniles began to elicit gregarious settlement after approximately 96 h. Extraction of aggregations of adult Worms with organic solvents removed the inductive capacity of the tissue, and activity was found in both nonpolar and polar fractions of an extraction series.
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settlement of a marine Tube Worm as a function of current velocity interacting effects of hydrodynamics and behavior1
Limnology and Oceanography, 1993Co-Authors: Joseph R Pawlik, Cheryl Ann ButmanAbstract:Settlement cxpcriments were conducted with larvae of Phragmatopoma lapidosa callfirnica (a reefbuilding sabcllariid polychaetc) in turbulent flume flows (near-surface velocities of 5, 10, 15, 20, 25, 30, and 35 cm s-l) over a hydrodynamically smooth bed. Boundary shear velocities spanned the critical shear velocity for initiation of particle motion and for suspended-load transport of passive larval mimics. Larvae were allowed one pass over a scdimcnt array with two treatments: Tube sand, a natural inducer of metamorphosis, and noninductive sand. Delivery of larvae to the array was the result of interactions between the flow regime and larval behavior. At intermediate flows (15, 20, and 25 cm s-l), where numbers of metamorphosed juveniles and total animals (larvae + juveniles) in the array were maximal, larvae tumbled along the flume bottom, as did the passive larval mimics. At slower llows, larvae actively left the bottom and swam into the water, passing over the array. At the fastest flows, hydrodynamics alone may have reduced settlement because larvae, like the mimics, were eroded from the bed and carried as suspended load over the array or because enhanced turbulent mixing distributed larvae more evenly in the water, thus reducing their concentration close to the bed. Once delivered to the substratum, behavioral responses to chemical cues were ultimately responsible for metamorphosis; in all flows, > 96% of metamorphosed juveniles were in the Tube sand, whereas most unmetamorphosed larvae were in noninductive sand.
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hydrodynamic facilitation of gregarious settlement of a reef building Tube Worm
Science, 1991Co-Authors: Joseph R Pawlik, Cheryl Ann Butman, Victoria R StarczakAbstract:Experiments testing the effects of hydrodynamic processes and chemical cues on substrate selection were conducted with larvae of the marine Tube Worm Phragmatopoma lapidosa californica. In flume experiments, larvae were presented an array of sand treatments, including two substrates previously shown to induce metamorphosis in this species, under fast and slow flow regimes. Larvae preferentially metamorphosed on the inductive substrates in both flows. Delivery to the array was higher in fast flow because larvae tumbled along the bottom, whereas in slow flow, larvae were observed swimming in the water column. Thus, in addition to chemical cues, behavioral responses to flow conditions may play an important role in larval recruitment to the benthos.
Robert J Toonen - One of the best experts on this subject based on the ideXlab platform.
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settlement of the gregarious Tube Worm hydroides dianthus polychaeta serpulidae i gregarious and nongregarious settlement
Marine Ecology Progress Series, 2001Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:We conducted still-water time-course experiments on cultured larvae of the serpulid polychaete Hydroides dianthus (Verrill, 1873) to examine timing and patterns of gregarious and non- gregarious settlement to better understand the conditions under which larvae of a gregarious species colonize new habitats. We first confirmed that these Worms are aggregated in the field, and quanti- fied patterns of association with a number of other common intertidal species. Patterns of negative association with spatial competitors is unlikely to have resulted from larval avoidance during settle- ment, because we found no difference in larval settlement in response to conspecifics with or without the solitary tunicate Ascidia interrupta present. We then examined the settlement of competent lar- vae in response to biofilm and conspecifics to determine the conditions under which the larvae of this gregarious species settle nongregariously. Larvae settled concurrently in response to both biofilm and conspecifics, starting approximately 4 d after fertilization, and response was of similar magnitude to both biofilm and to conspecifics for the first couple of days post-competency. While settlement in response to conspecifics continued in subsequent assays carried out over 70 d (at which time larvae began to die in culture), settlement in response to biofilm decreased abruptly after the peak, and ceased by Day 14. Settlement patterns were qualitatively similar regardless of previous exposure to substrata; similar results were obtained whether the whole population of larvae in culture was denied access to or daily provided access to 1 or both experimental substrata. Furthermore, these patterns of settlement did not change as larval planktonic period was prolonged. Of larvae settling during 24 h sample assays, the majority of larvae metamorphosed in response to biofilm during the first 6 h, whereas metamorphosis in the final 6 h (between 18 and 24 h) of the assays was primarily in response to conspecifics. These results are opposite to the pattern predicted by the desperate larva hypothesis, because some larvae settled in response to biofilm even after rejecting conspecifics the previous day. In fact, cultures of competent larvae appear to become more specific in terms of larval settlement in response to live adult conspecifics as the planktonic period is artificially prolonged.
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settlement of the gregarious Tube Worm hydroides dianthus polychaeta serpulidae ii testing the desperate larva hypothesis
Marine Ecology Progress Series, 2001Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:We have documented patterns of gregarious and nongregarious settlement among the larvae of the gregarious Tube Worm Hydroides dianthus (Verrill, 1873) and shown that larvae do not exhibit decreased substratum-specificity throughout a prolonged planktonic period regardless of prior exposure to experimental substrata. Previous investigations with barnacles and polychaetes have suggested that the colonization of new substrata occurs because larvae become less discrimi- nating as they age, i.e. that they become 'desperate' to settle after searching unsuccessfully for con- specifics for some period of time. This hypothesis, first proposed by Knight-Jones & Wilson, is based on an energetic model in which non-feeding (lecithotrophic) larvae continue to search for specific substrata as long as their energetic reserves allow, but begin to accept sub-optimal habitat rather than exhaust their reserves and die without metamorphosing. Here, we examined whether it is pos- sible to induce decreased substratum-specificity among competent larvae of the gregarious Tube Worm H. dianthus, which has feeding (planktotrophic) larvae. We show that neither altered feeding regimes nor larval starvation lead to decreased substratum-specificity among competent larvae; although larvae maintained at lower food concentrations take longer to reach competency, the qual- itative patterns of settlement on biofilm and conspecifics is unaltered by feeding regime. Further- more, starving competent larvae results in a loss of competency rather than larval desperation. Lar- vae belonging to different size classes ( 127 µm) showed similar patterns of settlement, and differences among sibling cultures with different mean larval sizes resulted from a decrease in the proportion of larvae settling in response to conspecifics rather than an increase in the proportion settling in response to biofilm. We examined a number of obvious life-his- tory characters for correlations with the tendency for larvae to settle nongregariously, and found that although a variety of life-history traits showed significant correlations, only the total number of eggs spawned by a dam was significantly correlated with the proportion of larvae settling in response to biofilm (r 2 = 0.19), and the slope of this relationship was negative. These results are again diametric to predictions of the desperate larva hypothesis, and indicate that larval desperation is unlikely to be a general explanation for the initiation of monospecific aggregations of fouling marine invertebrates.
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settlement of the Tube Worm hydroides dianthus polychaeta serpulidae cues for gregarious settlement
Marine Biology, 1996Co-Authors: Robert J Toonen, Joseph R PawlikAbstract:The larvae of many benthic marine invertebrates settle to form conspecific aggregations and are thought to rely on chemical cues associated with adults as indicators of habitat suitability, although the identification of inductive compounds has proven difficult. Still-water laboratory assays carried out during the summers of 1992 and 1993 with larvae of the serpulid polychaete, Hydroides dianthus (Verrill, 1873), demonstrate that unidentified water-borne compound(s) were responsible for gregarious settlement of competent larvae. Unlike inductive compounds associated with other Tube-dwelling polychaetes, the settlement cue was soluble in water and was not associated with the Tube, but rather with the body of live adults. In assay chambers divided by a 52-μm mesh barrier, a greater percentage of larvae settled on biofilmed substrata when adult Worms were present on the other side of the barrier than when adults were absent. Settlement in response to conspecific adults, live Worms removed from their Tubes, and amputated tentacular crowns of live Worms was significantly greater than settlement in response to dead Worms, empty Tubes, or biofilmed slides. The settlement inducer appears to emanate from the openings of occupied Tubes; settlement was greatest along the anterior two-fifths of the Tube of living conspecific adults. A single adult was equally capable of eliciting a gregarious response as were five or 25 conspecifics, and newly settled juveniles began to elicit gregarious settlement after approximately 96 h. Extraction of aggregations of adult Worms with organic solvents removed the inductive capacity of the tissue, and activity was found in both nonpolar and polar fractions of an extraction series.
Guy Herve - One of the best experts on this subject based on the ideXlab platform.
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Enzyme distribution and metabolite exchange in the symbiosis between the deep-sea Tube Worm, Riftia pachyptila, and its bacterial endosymbiont
Symbiosis, 2007Co-Authors: Guy Herve, Zoran MinicAbstract:Riftia pachyptila is a Tube Worm living around the deep-sea vents along the East-Pacific Rise. Lacking a digestive track it is dependent on an obligate symbiosis with sulfide-oxidizing bacteria which are located in the bacteriocytes constituting the tissue of the Worm called trophosome. The enzymological and biochemical aspects of this symbiosis were studied with respect to the anabolic and catabolic pathways involved in pyrimidine and arginine metabolism. The results obtained demonstrate the importance of the metabolic exchanges between the two partners and the complexity of their interactions.
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Arginine metabolism in the deep sea Tube Worm Riftia pachyptila and its bacterial endosymbiont.
The Journal of biological chemistry, 2003Co-Authors: Zoran Minic, Guy HerveAbstract:The present study describes the distribution and properties of enzymes involved in arginine metabolism in Riftia pachyptila, a TubeWorm living around deep sea hydrothermal vents and known to be engaged in a highly specific symbiotic association with a bacterium. The results obtained show that the arginine biosynthetic enzymes, carbamyl phosphate synthetase, ornithine transcarbamylase, and argininosuccinate synthetase are present in all of the tissues of the Worm and in the bacteria. Thus, Riftia and its bacterial endosymbiont can assimilate nitrogen and carbon via this arginine biosynthetic pathway. The kinetic properties of ornithine transcarbamylase strongly suggest that neither Riftia nor the bacteria possess the catabolic form of this enzyme belonging to the arginine deiminase pathway, the absence of this pathway being confirmed by the lack of arginine deiminase activity. Arginine decarboxylase and ornithine decarboxylase are involved in the biosynthesis of polyamines such as putrescine and agmatine. These activities are present in the trophosome, the symbiont-harboring tissue, and are higher in the isolated bacteria than in the trophosome, indicating that these enzymes are of bacterial origin. This finding indicates that Riftia is dependent on its bacterial endosymbiont for the biosynthesis of polyamines that are important for its metabolism and physiology. These results emphasize a particular organization of the arginine metabolism and the exchanges of metabolites between the two partners of this symbiosis.
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contribution of the bacterial endosymbiont to the biosynthesis of pyrimidine nucleotides in the deep sea Tube Worm riftia pachyptila
Journal of Biological Chemistry, 2001Co-Authors: Zoran Minic, Valerie Simon, Bernadette Penverne, Francoise Gaill, Guy HerveAbstract:Abstract The deep-sea Tube Worm Riftia pachyptila (Vestimentifera) from hydrothermal vents lives in an intimate symbiosis with a sulfur-oxidizing bacterium. That involves specific interactions and obligatory metabolic exchanges between the two organisms. In this work, we analyzed the contribution of the two partners to the biosynthesis of pyrimidine nucleotides through both the “de novo” and “salvage” pathways. The first three enzymes of the de novo pathway, carbamyl-phosphate synthetase, aspartate transcarbamylase, and dihydroorotase, were present only in the trophosome, the symbiont-containing tissue. The study of these enzymes in terms of their catalytic and regulatory properties in both the trophosome and the isolated symbiotic bacteria provided a clear indication of the microbial origin of these enzymes. In contrast, the succeeding enzymes of this de novo pathway, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase, were present in all body parts of the Worm. This finding indicates that the animal is fully dependent on the symbiont for the de novo biosynthesis of pyrimidines. In addition, it suggests that the synthesis of pyrimidines in other tissues is possible from the intermediary metabolites provided by the trophosomal tissue and from nucleic acid degradation products since the enzymes of the salvage pathway appear to be present in all tissues of the Worm. Analysis of these salvage pathway enzymes in the trophosome strongly suggested that these enzymes belong to the Worm. In accordance with this conclusion, none of these enzyme activities was found in the isolated bacteria. The enzymes involved in the production of the precursors of carbamyl phosphate and nitrogen assimilation, glutamine synthetase and nitrate reductase, were also investigated, and it appears that these two enzymes are present in the bacteria.
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the enzymes involved in synthesis and utilization of carbamylphosphate in the deep sea Tube Worm riftia pachyptila
Marine Biology, 2000Co-Authors: Valerie Simon, Francoise Gaill, Cristina Purcarea, K Sun, J Joseph, Ghislaine Frebourg, Jeanpierre Lechaire, Guy HerveAbstract:The obligate symbiosis of the deep-sea Tube Worm Riftia pachyptila with a sulphur-oxidizing bacterium raises important questions concerning its metabolism and metabolic exchanges. In this study, the presence and properties of the enzymes synthesizing and utilizing carbamylphosphate in the arginine and pyrimidine nucleotide pathways were investigated in this Worm. The results show that the ammonium-dependent carbamylphosphate synthetase and ornithine transcarbamylase, enzymes involved in the arginine pathway, are present in all body parts of the Worm. In contrast, the glutamine-dependent carbamylphosphate synthetase and aspartate transcarbamylase, enzymes involved in the de novo pathway for pyrimidine nucleotides biosynthesis, are present only in the trophosome, the symbiont-harbouring tissue. Although the bacterial nature of these enzymes is not unambigously established, these results strongly suggest that the de novo biosynthesis of pyrimidine nucleotides is limited to the trophosome, the organ where the production of metabolic energy takes place, while the other parts of the Worm's body rely on the salvage pathway for the production of the pyrimidine triphosphate nucleotides.
François H. Lallier - One of the best experts on this subject based on the ideXlab platform.
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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}...
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S-Sulfohemoglobin and disulfide exchange: The mechanisms of sulfide binding by Riftia pachyptila hemoglobins
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Franck Zal, François H. Lallier, Andre Toulmond, Emmanuelle Leize, Alain Van Dorsselaer, James J. ChildressAbstract:The deep sea hydrothermal Tube Worm Riftia pachyptila possesses a multihemoglobin system with three different extracellular hemoglobins (Hbs; V1, V2, and C1): two dissolved in the vascular blood, V1 and V2, and one in the coelomic fluid, C1. V1 consists of four heme-containing chains and four linker chains. The globin chains making up V2 and C1 are, with one exception, common to V1. Remarkably these Hbs are able to bind oxygen and sulfide simultaneously and reversibly at two different sites. Two of the globin chains found in these three Riftia Hbs possess one free Cys residue and for at least one of the globins, the b-Cys75 is conserved among vestimentifera (Lamellibrachia sp.) and pogonophora (Oligobrachia mashikoi). By selectively blocking the free Cys with N-ethylmaleimide and using electrospray ionization mass spectrometry experiments, we show that these Cys residues are involved in sulfide binding by Riftia Hbs. Moreover, we also demonstrate that the larger V1 Hb can form persulfide groups on its linker chains, a mechanism that can account for the higher sulfide-binding potential of this Hb.
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Partially glucose-capped oligosaccharides are found on the hemoglobins of the deep-sea Tube Worm Riftia pachyptila
Glycobiology, 1998Co-Authors: Franck Zal, Bernhard Kuster, N Green Brian, David J. Harvey, François H. LallierAbstract:We report here the structural determination of N-linked oligosaccharides found on extracellular hemoglobins of the hydrothermal vent Tube Worm Riftia pachyptila. Structures were elucidated by a combination of electrospray ionization tandem mass spectrometry, matrix-assisted laser desorption/ionization mass spectrometry, normal-phase high performance liquid chromatography, and exoglycosidase digestion. The sugar chains were found to consist mainly of high-mannose-type glycans with some structures partially capped by one or two terminal glucose residues. The present study represents the first report of the occurrence of glucose capping of N-linked carbohydrates in a secreted glycoprotein of a metazoan. Previously, glucose capping has only been described for a membrane-bound surface glycoprotein from the unicellular parasite Leishmania mexicana amazonensis.
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primary structure of the common polypeptide chain b from the multi hemoglobin system of the hydrothermal vent Tube Worm riftia pachyptila an insight on the sulfide binding site
Proteins, 1997Co-Authors: James J. Childress, Franck Zal, François H. Lallier, Tomohiko Suzuki, Y Kawasaki, Andre ToulmondAbstract:The deep-sea Tube Worm Riftia pachyptila Jones possesses a multi-hemoglobin system with three different extracellular Hbs: two dissolved in the vascular blood, V1 (ca. 3,500 kDa) and V2 (ca. 400 kDa), and one in the coelomic fluid, C1 (ca. 400 kDa). V1 Hb consists of four heme-containing, globin chains (b-e) and four linker chains (L1-L4). V2 and C1 Hbs are exclusively built from globin chains, six for V2 (a-f) and five for C1 (a-e). The complete amino acid sequence of the isolated monomeric globin chain b, common to all Riftia Hbs, has been determined by automated Edman degradation sequencing of the peptides derived by digestion with trypsin, chymotrypsin, thermolysin, and CNBr. This polypeptide chain is composed of 144 amino acid residues, providing a M(r) of 16, 135.0 Da. Moreover, the primary sequence of chain b revealed 3 Cys residues at position 4, 75, and 134. Cys-4 and Cys-134 are located at positions where an intra-chain disulfide bridge is formed in all annelid, vestimentiferan, or pogonophoran chains, but Cys-75 is located at a unique position only found in three globin chains belonging to Lamellibrachia and Oligobrachia, a vestimentiferan and a pogonophoran. In both groups, Hbs can bind sulfide reversibly to fuel the chemosynthetic process of the symbiotic bacteria they harbor. Sulfide-binding experiments performed on purified Hb fractions (i.e., V1, V2, and C1 Hbs) suggest that free Cys residues on globin chains, and the numerous Cys found in linker chains, as determined previously by ESI-MS, may be the sulfide binding-sites. Blocking the free Cys by N-ethylmaleimide, we confirmed that free cysteines were involved in sulfide-binding but did not account for the whole sulfide-binding capacity of V1 Hb. Furthermore, a phylogenetic tree was constructed from 18 globin-like chains of annelid, vestimentiferan, and pogonophoran extracellular Hbs to clarify the systematic position of TubeWorms. Riftia chain b clearly belongs to the "strain A" family with 30 to 80% identity with the other sequences analyzed. Its position in the tree confirmed a close relationship between vestimentiferan, pogonophoran, and annelid Hbs.
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three dimensional reconstruction of the hexagonal bilayer hemoglobin of the hydrothermal vent Tube Worm riftia pachyptila by cryoelectron microscopy
Proteins, 1996Co-Authors: Felix De Haas, Franck Zal, François H. Lallier, Andre Toulmond, Jean N LamyAbstract:A frozen-hydrated specimen of the V1 hemoglobin of the hydrothermal vent Tube Worm Riftia pachyptila was observed in the electron microscope and subjected to three-dimensional reconstruction by the method of random conical tilt series. The 3D volume possesses a D6 point-group symmetry. When viewed along its 6-fold axis the vertices of its upper hexagonal layer are 16 degrees clockwise rotated compared to those of the lower layer. A central linker complex is decorated by 12 hollow globular substructures. The linker complex comprises (i) a central hexagonal toroid, (ii) two internal bracelets onto which the hollow globular substructures are built, and (iii) six structures connecting the two hexagonal layers. The hollow globular substructures, related to the dodecamers of globin chains resulting from the dissociation of the hexagonal bilayer hemoglobin, have a local pseudo 3-fold symmetry and are composed each of three elongated structures visible when the volume is displayed at high threshold. At a resolution of 36 A, the 3D volumes of the hexagonal bilayer hemoglobins of Riftia pachyptyla and of the leech Macrobdella decora look almost perfectly identical.
Franck Zal - One of the best experts on this subject based on the ideXlab platform.
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S-Sulfohemoglobin and disulfide exchange: The mechanisms of sulfide binding by Riftia pachyptila hemoglobins
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Franck Zal, François H. Lallier, Andre Toulmond, Emmanuelle Leize, Alain Van Dorsselaer, James J. ChildressAbstract:The deep sea hydrothermal Tube Worm Riftia pachyptila possesses a multihemoglobin system with three different extracellular hemoglobins (Hbs; V1, V2, and C1): two dissolved in the vascular blood, V1 and V2, and one in the coelomic fluid, C1. V1 consists of four heme-containing chains and four linker chains. The globin chains making up V2 and C1 are, with one exception, common to V1. Remarkably these Hbs are able to bind oxygen and sulfide simultaneously and reversibly at two different sites. Two of the globin chains found in these three Riftia Hbs possess one free Cys residue and for at least one of the globins, the b-Cys75 is conserved among vestimentifera (Lamellibrachia sp.) and pogonophora (Oligobrachia mashikoi). By selectively blocking the free Cys with N-ethylmaleimide and using electrospray ionization mass spectrometry experiments, we show that these Cys residues are involved in sulfide binding by Riftia Hbs. Moreover, we also demonstrate that the larger V1 Hb can form persulfide groups on its linker chains, a mechanism that can account for the higher sulfide-binding potential of this Hb.
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Partially glucose-capped oligosaccharides are found on the hemoglobins of the deep-sea Tube Worm Riftia pachyptila
Glycobiology, 1998Co-Authors: Franck Zal, Bernhard Kuster, N Green Brian, David J. Harvey, François H. LallierAbstract:We report here the structural determination of N-linked oligosaccharides found on extracellular hemoglobins of the hydrothermal vent Tube Worm Riftia pachyptila. Structures were elucidated by a combination of electrospray ionization tandem mass spectrometry, matrix-assisted laser desorption/ionization mass spectrometry, normal-phase high performance liquid chromatography, and exoglycosidase digestion. The sugar chains were found to consist mainly of high-mannose-type glycans with some structures partially capped by one or two terminal glucose residues. The present study represents the first report of the occurrence of glucose capping of N-linked carbohydrates in a secreted glycoprotein of a metazoan. Previously, glucose capping has only been described for a membrane-bound surface glycoprotein from the unicellular parasite Leishmania mexicana amazonensis.
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primary structure of the common polypeptide chain b from the multi hemoglobin system of the hydrothermal vent Tube Worm riftia pachyptila an insight on the sulfide binding site
Proteins, 1997Co-Authors: James J. Childress, Franck Zal, François H. Lallier, Tomohiko Suzuki, Y Kawasaki, Andre ToulmondAbstract:The deep-sea Tube Worm Riftia pachyptila Jones possesses a multi-hemoglobin system with three different extracellular Hbs: two dissolved in the vascular blood, V1 (ca. 3,500 kDa) and V2 (ca. 400 kDa), and one in the coelomic fluid, C1 (ca. 400 kDa). V1 Hb consists of four heme-containing, globin chains (b-e) and four linker chains (L1-L4). V2 and C1 Hbs are exclusively built from globin chains, six for V2 (a-f) and five for C1 (a-e). The complete amino acid sequence of the isolated monomeric globin chain b, common to all Riftia Hbs, has been determined by automated Edman degradation sequencing of the peptides derived by digestion with trypsin, chymotrypsin, thermolysin, and CNBr. This polypeptide chain is composed of 144 amino acid residues, providing a M(r) of 16, 135.0 Da. Moreover, the primary sequence of chain b revealed 3 Cys residues at position 4, 75, and 134. Cys-4 and Cys-134 are located at positions where an intra-chain disulfide bridge is formed in all annelid, vestimentiferan, or pogonophoran chains, but Cys-75 is located at a unique position only found in three globin chains belonging to Lamellibrachia and Oligobrachia, a vestimentiferan and a pogonophoran. In both groups, Hbs can bind sulfide reversibly to fuel the chemosynthetic process of the symbiotic bacteria they harbor. Sulfide-binding experiments performed on purified Hb fractions (i.e., V1, V2, and C1 Hbs) suggest that free Cys residues on globin chains, and the numerous Cys found in linker chains, as determined previously by ESI-MS, may be the sulfide binding-sites. Blocking the free Cys by N-ethylmaleimide, we confirmed that free cysteines were involved in sulfide-binding but did not account for the whole sulfide-binding capacity of V1 Hb. Furthermore, a phylogenetic tree was constructed from 18 globin-like chains of annelid, vestimentiferan, and pogonophoran extracellular Hbs to clarify the systematic position of TubeWorms. Riftia chain b clearly belongs to the "strain A" family with 30 to 80% identity with the other sequences analyzed. Its position in the tree confirmed a close relationship between vestimentiferan, pogonophoran, and annelid Hbs.
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three dimensional reconstruction of the hexagonal bilayer hemoglobin of the hydrothermal vent Tube Worm riftia pachyptila by cryoelectron microscopy
Proteins, 1996Co-Authors: Felix De Haas, Franck Zal, François H. Lallier, Andre Toulmond, Jean N LamyAbstract:A frozen-hydrated specimen of the V1 hemoglobin of the hydrothermal vent Tube Worm Riftia pachyptila was observed in the electron microscope and subjected to three-dimensional reconstruction by the method of random conical tilt series. The 3D volume possesses a D6 point-group symmetry. When viewed along its 6-fold axis the vertices of its upper hexagonal layer are 16 degrees clockwise rotated compared to those of the lower layer. A central linker complex is decorated by 12 hollow globular substructures. The linker complex comprises (i) a central hexagonal toroid, (ii) two internal bracelets onto which the hollow globular substructures are built, and (iii) six structures connecting the two hexagonal layers. The hollow globular substructures, related to the dodecamers of globin chains resulting from the dissociation of the hexagonal bilayer hemoglobin, have a local pseudo 3-fold symmetry and are composed each of three elongated structures visible when the volume is displayed at high threshold. At a resolution of 36 A, the 3D volumes of the hexagonal bilayer hemoglobins of Riftia pachyptyla and of the leech Macrobdella decora look almost perfectly identical.
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The Multi-hemoglobin System of the Hydrothermal Vent Tube Worm Riftia pachyptila I. REEXAMINATION OF THE NUMBER AND MASSES OF ITS CONSTITUENTS
The Journal of biological chemistry, 1996Co-Authors: Franck Zal, François H. Lallier, Joseph S. Wall, Serge N. Vinogradov, Andre ToulmondAbstract:Abstract The deep-sea Tube Worm Riftia pachyptila Jones possesses a well developed circulatory system and a large coelomic compartment, both containing extracellular hemoglobins. Fresh vascular blood is heterogeneous and contains two different hemoglobins (V1 and V2), whereas the coelomic fluid is homogeneous and comprises only one hemoglobin (C1). Their molecular weights have been determined by scanning transmission electron microscopy mass mapping (STEM) and by multi-angle laser light scattering (MALLS). Both methods yielded approximately the same molecular weights with masses significantly higher than the literature data for V1. V1, V2, and C1 had M of 3396 ± 540 × 103, 393 ± 71 × 103, and 410 ± 51 × 103 by STEM, and 3503 ± 13 × 103, 433 ± 8 × 103, and 380 ± 4 × 103 by MALLS, respectively. Transmission electron micrographs of V1 are typical of an hexagonal bilayer hemoglobin (HBL Hb). When submitted to dilution or osmotic shock, V1 dissociates into halves and one-twelfth subunits like annelid HBL Hbs. V1 is resistant to urea treatment, indicating that hydrophobic interactions play a small role in its quaternary structure. Conversely, V1 Hb is rather unstable in solution without denaturant, a property which seems to be characteristic of vestimentiferan HBL Hbs and could be explained by an important number of hydrogen bonds.
