vivo clearance of enteric bacteria from the hemolymph of the hard clam and the american oyster.american oysters, crassostrea virginica, and hard clams, mercenaria mercenaria, were experimentally contaminated with escherichia coli, salmonella typhimurium, and shigella flexneri either by intracardial injection or via the natural route of ingestion. bacterial inactivation in the hemolymph was monitored for 72 h after exposure to these enteric pathogens at 20 and 6 degrees c. at 6 degrees c, both mean bacterial uptake by ingestion and subsequent clearance was singificantly lower that at 20 de ...1979378127
in situ morphology of nitrifying-like bacteria in aquaculture systems.the in situ microbiota from several aquaculture facilities with active nitrification was examined by transmission electron microscopy of thin sections for the presence of bacteria that contained intracytoplasmic membranes characteristic of the nitrifying bacteria. colonies of bacteria with the cellular morphology of a species of nitrosomonas were found to be present in both the culture water and in the biological filter slime of a freshwater chinook salmon (oncorhynchus tshawytscha) culture syst ...1976938036
seasonal effects on accumulation of microbial indicator organisms by mercenaria mercenaria.the ability of hard-shelled clams (mercenaria mercenaria) to accumulate fecal coliforms and other microorganisms (escherichia coli, clostridium perfringens, and male-specific bacteriophages) was determined over a 1-year period. twenty separate trails were conducted during different seasons to encompass a wide range of water temperatures. the greatest accumulation of microorganisms in hard-shelled clams occurred during certain periods in the spring, at temperatures ranging from 11.5 to 21.5 degre ...19921575484
survival and replication of male-specific bacteriophages in molluscan shellfish.the survival and replication of male-specific bacteriophages in hard-shelled clams (mercenaria mercenaria) and their homogenates were examined to further assess their potential utility as indicator organisms. trials were conducted in the presence and absence of a suitable bacterial host, escherichia coli hs[pfamp]r. results of this study demonstrated that male-specific bacteriophages were unable to replicate in hard-shelled clams, with or without added host cells. in addition, the densities of t ...19921599255
phagocytosis by hemocytes of the hard clam, mercenaria mercenaria.large granular hemocytes of mercenaria mercenaria avidly phagocytose a variety of biological particles (red blood cells of six species, yeast, and gram-positive and gram-negative bacteria) as well as polystyrene spheres. clam hemolymph is not necessary for phagocytosis but may have some opsonic effect in certain circumstances (e.g., low temperature and low particle density). formaldehyde treatment of red blood cells enhances susceptibility to phagocytosis. phagocytosis by mercenaria hemocytes in ...19921607668
agglutinins in the hemolymph of the hard clam, mercenaria mercenaria.lectins in the serum of the clam mercenaria mercenaria agglutinate some red blood cells, bacteria, and yeast. the interaction of these substances with particles is affected by sugars, ions, temperature, and alteration of particle surfaces. lectins are not needed for phagocytosis of foreign particles in vitro. in m. mercenaria these recognition molecules do not enhance defense mechanisms.19921607669
a method for the enumeration of poliovirus in selected molluscan shellfish.a virus extraction procedure was developed and evaluated on five commercially important molluscan shellfish species: crassostrea virginica (eastern oyster), mya arenaria (softshell clam), mytilus edulis (blue mussel), mercenaria mercenaria (hardshell clam), and crassostrea gigas, (pacific oyster). shellfish tissue homogenates were spiked with poliovirus, extracted, and plaque assayed. mean virus recoveries were: c. virginica, 63.8%; m. arenaria, 42.1%; m. edulis, 67.3%; m. mercenaria, 48.3%; and ...19892559103
relationships between the fmrfamide-related peptides and other peptide families.the relationships between peptide families are recognized in terms of structural similarity and immunological and biological activity. most of the currently known fmrfamide-related peptides (farps) of molluscs were tested in a radioimmunoassay (ria) and in the two standard bioassays for fmrfamide: the radula protractor muscle of the whelk busycon contrarium, and the isolated heart of the clam mercenaria mercenaria. some peptides were also tested on the heart of the snail helix aspersa. the respo ...19882908809
anticoagulantly active heparin from clam (mercenaria mercenaria).heparin was isolated from mercenaria mercenaria by ion-exchange chromatography and was fractionated into two distinct populations with immobilized antithrombin. the high-affinity glycosaminoglycan accelerated dramatically the inhibition of purified human factors iia and xa via purified human antithrombin. specific anti-factor iia and anti-factor xa activities were 363 and 348 u.s.p. units/mg, respectively. the highly active clam heparin exhibited a molecular weight of approximately 18,000 and co ...19863740845
accumulation of escherichia coli by the northern quahaug.the uptake of escherichia coli by the quahaug, mercenaria mercenaria, was studied to obtain an insight into the environmental parameters significant to the accumulation of bacterial pathogens by shellfish growing in polluted waters and into the kinetics of the uptake process. experimental uptake was achieved by placing the animals in a flowing water system in which the contamination level of the water and its temperature and salinity could be controlled. data from periodic assays of individual a ...19704908527
accumulation and elimination of coliphage s-13 by the hard clam, mercenaria mercenaria.accumulation and elimination of viral particles by hard clams, mercenaria mercenaria, were studied with the coliphage s-13 as a working model. escherichia coli uptake and elimination were simultaneously monitored. clams were exposed to low levels of s-13 (7 particles/ml) in running seawater for several days, achieving titers in tissues from 2 to more than 1,000 times the levels to which they had been exposed. bacterial accumulation (previously established by other workers) was comparable. upon e ...19714935489
inhibition of effects of leukemogenic viruses in mice by extracts of mercenaria mercenaria. 19665924464
inefficient accumulation of low levels of monodispersed and feces-associated poliovirus in oysters.the accumulation of low levels (0.002 to 0.18 pfu/ml) of both feces-associated and monodispersed poliovirus by oysters (crassostrea virginica or c. gigas) and clams (mercenaria mercenaria) was investigated. these levels were chosen to duplicate the conditions present in light to moderately polluted waters. experiments were performed in both small- and large-scale flowing seawater systems, developed to mimic the natural marine habitats of shellfish. under these experimental conditions, viral accu ...19826297388
accumulation of sediment-associated viruses in shellfish.the present study focused on the importance of contaminated sediments in shellfish accumulation of human viruses. epifaunal (crassostrea virginica) and infaunal (mercenaria mercenaria) shellfish, placed on or in cores, were exposed to either resuspended or undisturbed sediments containing bound poliovirus type 1 (lsc 2ab). consistent bioaccumulation by oysters (four of five trials) was only noted when sediment-bound viruses occurred in the water column. virus accumulation was observed in a singl ...19836297392
activation of mammalian carcinogens to bacterial mutagens by microsomal enzymes from a pelecypod mollusk, mercenaria mercenaria.several kinds of neoplastic diseases have been described in mollusks collected from the field. the etiology of these lesions is unknown; however, the involvement of chemical carcinogens has been suggested. experimental models for chemically-induced neoplasia in bivalves have yet to be developed. we have obtained data which suggest that aromatic amines may be more appropriate candidates than polycyclic aromatic hydrocarbons for putative molluscan carcinogens. digestive gland enzymes from a bivalv ...19836339894
accumulation and elimination of escherichia coli and salmonella typhimurium by hard clams in an in vitro system.a simple, in vitro protocol was devised to study contamination by and subsequent elimination of escherichia coli and salmonella typhimurium in the hard clam, mercenaria mercenaria. the test bacteria were eliminated rapidly at similar rates for 8 h after exposure and less rapidly thereafter. at 24 h, numbers of e. coli had declined more than s. typhimurium. bacteria were cleared in the form of rapidly sedimenting fecal and pseudofecal particulates with which the bacteria were stably associated. i ...19846378093
organochlorine residues in shellfish from maryland waters, 1976-1980.shellfish samples, including the american oyster (craessostrea virginica), the soft shell clam (mya arenaria), the hard shell clam (mercenaria mercenaria) and the blue crab (callinectes sapidus), were taken from the maryland section of the chesapeake bay and its tributaries over a five year period (1976-80) and analyzed to determine residue levels of various organochlorine pesticides. qualitative and quantitative information was obtained for a variety of polychlorinated hydrocarbons. the purpose ...19846501793
inducible hemolytic activity in mercenaria mercenaria hemolymph. 19817319106
analysis of glycosphingolipids by fluorophore-assisted carbohydrate electrophoresis using ceramide glycanase from mercenaria mercenaria.polyacrylamide gel electrophoresis of fluorophore-labeled saccharides is a simple and sensitive separation method for glycan analysis. this method requires an aldehydic reducing carbon on the saccharide in order to react with the amine group of the fluorophore (8-aminonaphthalene-1,3,6-trisulfonic acid or 2-aminoacridone). we have used exoglycosidase-free ceramide glycanase from hard-shelled clam to expose the reducing terminal of the glycan in glycosphingolipid by cleaving the linkage between t ...19947856860
chemotaxis of mercenaria mercenaria hemocytes to bacteria in vitro.hemocytes of the hard clam mercenaria mercenaria migrate toward secreted bacterial products in vitro by chemotaxis (i.e., by detection of an increasing chemical gradient of attractant). the attractants produced by escherichia coli are peptides or small proteins. clam hemocytes also migrate toward formyl-methionyl-leucyl-phenylalanine (fmlf), a mammalian neutrophil chemoattractant produced by bacteria, but not toward the related compound formyl-methionyl-valine. migration of hemocytes to fmlf was ...19948021525
effect of gamma irradiation on shelf life and bacterial and viral loads in hard-shelled clams (mercenaria mercenaria).the feasibility of using 60co gamma irradiation to inactivate total coliforms, fecal coliforms, escherichia coli, clostridium perfringens, and f-coliphage in hard-shelled clams, mercenaria mercenaria, was investigated. the results of three trials indicated average d10 values of 1.32 kgy for total coliforms, 1.39 kgy for fecal coliforms, 1.54 kgy for e. coli, 2.71 kgy for c. perfringens, and 13.50 kgy for f-coliphage. irradiation doses of > 0.5 kgy were significantly lethal to the shellfish.19948074539
detection of hepatitis a virus in mercenaria mercenaria by coupled reverse transcription and polymerase chain reaction.hepatitis a virus (hav) is a major cause of infectious hepatitis in humans. in this respect, bivalve mollusks pose a major health concern because they are filter feeders and can concentrate the virus up to 900-fold from contaminated water. detection of hav has been hampered because wild-type hav grows poorly if at all in cell culture. here we describe a technique for the detection of hav in shellfish based on reverse transcription coupled with the polymerase chain reaction. rna is isolated from ...19938215351
[international trade in bivalve mollusks and the current situation in france and in europe].over the last century and a half, trade in shellfish has introduced into france four new species intended for aquaculture, as follows: -the portuguese oyster (crassostrea angulata) -the american clam (mercenaria mercenaria) -the pacific oyster (c. gigas) -the manila clam (ruditapes philippinarum). the development of hatcheries and air transport facilities has led to increased trade in these species among the countries of the european union (france, ireland, italy, the netherlands, portugal, spai ...19969019238
effects of experience on crab foraging in a mobile and a sedentary speciesthe effects of experience on prey and prey-patch choice were compared between two species of marine predatory crabs. the blue crab, callinectes sapidus rathbun, is highly mobile and forages in a variety of estuarine and lagoonal habitats. the atlantic mud crab, panopeus herbstii h. milne-edwards, is smaller and less mobile and is found mostly in oyster reefs and on shelly bottoms. in the laboratory, crabs were offered a choice between two prey types (juvenile hard clams, mercenaria mercenaria li ...19979236012
virion concentration method for the detection of human enteric viruses in extracts of hard-shelled clams.a method to extract and concentrate intact human enteric viruses from oyster extracts for detection using reverse transcription-polymerase chain reaction (rt-pcr) was applied to hard-shelled clams (mercenaria mercenaria). fifty-gram clam samples were processed by an adsorption-elution-precipitation method and then seeded with 10(1) to 10(5) pfu to poliovirus 1 (pv1) and/or hepatitis a virus (hav). seeded viruses in extracts were purified by fluorocarbon (freon) extraction and concentrated by pol ...19989709210
calcium speciation and exchange between blood and extrapallial fluid of the quahog mercenaria mercenaria (l.).calcium and small organic molecules (e.g., tyrosine, mw 181 da) introduced into the extrapallial fluid (epf) of the quahog mercenaria mercenaria exhibit rapid fluxes across the outer mantle epithelium and are distributed throughout the circulatory system within 3 h. larger molecules (e.g., bovine serum albumin, mw 66,000 da) are less readily exchanged between epf and blood. the protein compositions of blood plasma and epf are different, with at least seven protein bands expressed more prominentl ...19989739548
recovery and detection of enterovirus, hepatitis a virus and norwalk virus in hardshell clams (mercenaria mercenaria) by rt-pcr methods.a method for recovery of enteric viruses from hardshell clams (mercenaria mercenaria) has been developed and evaluated. seeded 50-g samples of clam tissue homogenates were processed by adsorption elution precipitation, two fluorocarbon extractions and peg precipitation. clam concentrates were assayed by infectivity and by rt-pcr after guanidinium isothiocyanate (git) extraction and/or an indirect immunomagnetic capture (ic) of the virus using paramagnetic beads. git extraction removed pcr inhibi ...199910092141
description of perkinsus andrewsi n. sp. isolated from the baltic clam (macoma balthica) by characterization of the ribosomal rna locus, and development of a species-specific pcr-based diagnostic assay.a perkinsus species was isolated from the baltic clam macoma balthica and an in vitro culture established under conditions described for p. marinus. as reported previously, morphological features remarkable enough to clearly indicate that this isolate is a distinct perkinsus species were lacking. in this study, regions of the rrna locus (nts, 18s, its1, 5.8s, and its2) of this isolate were cloned, sequenced, and compared by alignment with those available for other perkinsus species and isolates. ...200111249193
microbiological quality and safety of quahog clams, mercenaria mercenaria, during refrigeration and at elevated storage temperatures.the effects of storage temperatures and times on the microbiological quality and safety of hard-shelled quahog clams (mercenaria mercenaria) were examined. samples were stored at four different incubation temperatures (3.3, 7.2, 10.0, and 12.8 degrees c) for a period of 3 weeks, following their harvest from summer growing waters (> or = 27 degrees c) and winter waters (< or = 4 degrees c). clams were analyzed for two naturally occurring pathogens, vibrio parahaemolyticus and vibrio vulnificus. d ...200111252477
rapid and efficient extraction method for reverse transcription-pcr detection of hepatitis a and norwalk-like viruses in part of an effort to develop a broadly applicable test for norwalk-like viruses and hepatitis a virus (hav) in shellfish, a rapid extraction method that is suitable for use with one-step reverse transcription (rt)-pcr-based detection methods was developed. the method involves virus extraction using a ph 9.5 glycine buffer, polyethylene glycol (peg) precipitation, tri-reagent, and purification of viral poly(a) rna by using magnetic poly(dt) beads. this glycine-peg-tri-reagent-poly(dt) method c ...200111526018
effects of plasma from bivalve mollusk species on the in vitro proliferation of the protistan parasite perkinsus marinus.the in vitro culture of the eastern oyster parasite perkinsus marinus has provided a unique opportunity to examine its susceptibility to putative recognition and effector defense mechanisms operative in refractory bivalve species. in this study, we report the effect of supplementing the culture medium with plasma from: (1) uninfected to heavily infected eastern oysters; (2) oyster species considered to be disease-resistant; and (3) bivalve mollusk species that are naturally exposed to the parasi ...200211857456
effects of the pathogenic vibrio tapetis on defence factors of susceptible and non-susceptible bivalve species: ii. cellular and biochemical changes following in vivo challenge.this work compared the effect of challenge with vibrio tapetis, the etiologic agent of brown ring disease (brd) in clams, and other bacterial strains on defence-related factors in four bivalve species: ruditapes philippinarum (highly susceptible to brd), r. decussatus (slightly susceptible to brd), mercenaria mercenaria and crassostrea virginica (both non-susceptible to brd). results show that bacterial challenge modulated defence-related factors, namely total and differential haemocyte counts, ...200616005645
effects of the pathogenic vibrio tapetis on defence factors of susceptible and non-susceptible bivalve species: i. haemocyte changes following in vitro microbial infections, the interaction between microorganisms and phagocytic cells is a crucial determinant in the outcome of the disease process. we used flow cytometry to study the in vitro interactions between vibrio tapetis, the bacterium responsible for brown ring disease (brd) in the manila clam ruditapes philippinarum, and haemocytes from three bivalve species: the manila clam (susceptible to brd), the hard clam mercenaria mercenaria and the eastern oyster crassostrea virginica (both no ...200616023865
hard clams (mercenaria mercenaria) evaluate predation risk using chemical signals from predators and injured conspecifics.hard clams, mercenaria mercenaria, are sessile, filter-feeding organisms that are heavily preyed upon by blue crabs, which find their clam prey using chemical cues. clams may evade blue crabs by reducing their pumping (feeding) behavior when a threat is perceived. the purpose of this study was to determine the type of signals that clams use to detect consumers. clams decreased their pumping time in response to blue crabs and blue crab effluent, but not to crab shells, indicating that chemical si ...200616586040
germinoma in razor clam ensis arcuatus (jeffreys, 1865) in galicia (nw spain).germinoma is a gonadal neoplasm originating from progenitor cells in germinal epithelium. over the last four decades it has been diagnosed in several species of marine bivalve molluscs but most consistently in some populations of mercenaria mercenaria and mya arenaria in north america. tissue sections of gonads from ensis arcuatus (family pharidae--superfamily solenacea), collected in ría de vigo (galicia-nw spain), revealed germinoma in both males and females. proliferating, undifferentiated, g ...200616905143
does gender really matter in contaminant exposure? a case study using invertebrate models.exposure to contaminants in the environment is indiscriminate and multiple species/populations of all sexes are potentially at risk. in this paper we examine the current information available on gender specific differences in invertebrates following exposure to environmental contaminants. because of their close association with the environment and diversity of habitats, invertebrates are uniquely at risk for adverse responses to pollutants. since 97% of all animal species are invertebrates, it w ...200717097631
oxidative burst in hard clam (mercenaria mercenaria) haemocytes.haemocytes of bivalve molluscs are known to be responsible for many immunological functions, including recognition, phagocytosis, and killing or elimination of invading microorganisms, such as potentially infective bacteria and parasites. in many bivalves, killing of microorganisms engulfed by haemocytes is accomplished by a sudden release of reactive oxygen species (ros) within the haemocytes; this response is referred to as an oxidative burst. previous studies have failed to detect oxidative b ...200717137792
toxicity of fipronil and its enantiomers to marine and freshwater non-targets.fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. in this study, the acute toxicity of the (s,+) and (r,-) enantiomers and the racemic mixture of fipronil were assessed using simulium vittatum is-7 (black fly), xenopus laevis (african clawed frog), procambarus clarkii (crayfish ...200717562454
prevalence of perkinsus marinus (dermo), haplosporidium nelsoni (msx), and qpx in bivalves of delaware's inland bays and quantitative, high-throughput diagnosis of dermo by qpcr.restoration of oyster reef habitat in the inland bays of delaware was accompanied by an effort to detect and determine relative abundance of the bivalve pathogens perkinsus marinus, haplosporidium nelsoni, and qpx. both the oyster crassostrea virginica and the clam mercenaria mercenaria were sampled from the bays. in addition, oysters were deployed at eight sites around the bays as sentinels for the three parasites. perkinsus marinus prevalence was measured with a real-time, quantitative polymer ...200718070329
assessment of the northern distribution range of selected perkinsus species in eastern oysters (crassostrea virginica) and hard clams (mercenaria mercenaria) with the use of pcr-based detection assays.perkinsus species are protistan parasites of molluscs. in chesapeake bay, perkinsus marinus, perkinsus chesapeaki, and perkinsus andrewsi are sympatric, infecting oysters and clams. although p. marinus is a pathogen for crassostrea virginica, it remains unknown whether p. andrewsi and p. chesapeaki are equally pathogenic. perkinsus species have been reported in c. virginica as far north as maine, sometimes associated with high prevalence, but low mortality. thus, we hypothesized that, in additio ...200818564742
minchinia mercenariae n. sp. (haplosporidia) in the hard clam mercenaria mercenaria: implications of a rare parasite in a commercially important host.during routine histopathology of 180 juvenile hard clams, mercenaria mercenaria, from a site in virginia, usa, in 2007, we discovered a single individual heavily infected with a parasite resembling a haplosporidian, some members of which cause lethal bivalve diseases. scanning electron microscopy of spores and sequencing of small subunit ribosomal dna confirmed a new species: minchinia mercenariae n. sp. further sampling of clams at the site found prevalences up to 38% using polymerase chain rea ...200919883442
hydrodynamic sensory stressors produce nonlinear predation patterns.predators often have large effects on community structure, but these effects can be minimized in habitats subjected to intense physical stress. for example, predators exert large effects on rocky intertidal communities on wave-protected shores but are usually absent from wave-swept shores where hydrodynamic forces prevent them from foraging effectively. the physical environment also can affect predation levels when stressors are not severe enough to be physically risky. in these situations, envi ...201020503871
Effects of Karenia brevis on clearance rates and bioaccumulation of brevetoxins in benthic suspension feeding invertebrates.Blooms of the toxic alga Karenia brevis occur along coastlines where sessile suspension feeding invertebrates are common components of benthic communities. We studied the effects of K. brevis on four benthic suspension feeding invertebrates common to the coast of the SE United States: the sponge Haliclona tubifera, the bryozoan Bugula neritina, the bivalve Mercenaria mercenaria, and the tunicate Styela plicata. In controlled laboratory experiments, we determined the rate at which K. brevis was c ...201222115907
phosphorylation of paramyosin and its possible role in the catch mechanism.paramyosin isolated from the adductor muscle of mercenaria mercenaria was shown to contain three to five phosphate groups/molecule; the actual number varied depending on the method used to extract the protein. dephosphorylation resulted in an increase in the solubility of paramyosin near ph 7 and near physiological ionic strength. this behavior suggests that the number of phosphates/molecule may be a determining factor in the aggregation behavior of paramyosin-containing myofilaments. thus, phos ...1975429279
inhibition of embryonic development of the hard clam, mercenaria mercenaria, by heavy metals. 20154433787
problems in establishing the relationship between pumping rate and oxygen consumption rate in the hard clam, mercenaria mercenaria. 1976236117
characterization of the transcriptome and temperature-induced differential gene expression in qpx, the thraustochytrid parasite of hard clams.the hard clam or northern quahog, mercenaria mercenaria, is one of the most valuable seafood products in the united states representing the first marine resource in some northeastern states. severe episodes of hard clam mortality have been consistently associated with infections caused by a thraustochytrid parasite called quahog parasite unknown (qpx). qpx is considered as a cold/temperate water organism since the disease occurs only in the coastal waters of the northwestern atlantic ocean from ...201424678810
identification and expression of differentially expressed genes in the hard clam, mercenaria mercenaria, in response to quahog parasite unknown (qpx).the hard clam, mercenaria mercenaria, has been affected by severe mortality episodes associated with the protistan parasite qpx (quahog parasite unknown) for several years. despite the commercial importance of hard clams in the united states, molecular bases of defense mechanisms in m. mercenaria, especially during qpx infection, remain unknown.200919682366
effect of high hydrostatic pressure processing on freely suspended and bivalve-associated t7 bacteriophage.the effectiveness of hydrostatic pressure processing (hpp) for inactivating viruses has been evaluated in only a limited number of studies, and most of the work has been performed with viruses freely suspended in distilled water. in this work, hpp inactivation of freely suspended and shellfish-associated bacteriophage t7 was studied. t7 was selected in hopes that it could serve as a model for animal virus behavior. clams (mercenaria mercenaria) and oysters (crassostrea virginica) were homogeneou ...200818326185
thermal inactivation kinetics of hepatitis a virus in homogenized clam meat (mercenaria mercenaria).epidemiological evidence suggests that hepatitis a virus (hav) is the most common pathogen transmitted by bivalve molluscs such as clams, cockles, mussels and oysters. this study aimed to generate thermal inactivation kinetics for hav as a first step to design adequate thermal processes to control clam-associated hav outbreaks.201526184406
differential immune response in the hard clam (mercenaria mercenaria) against bacteria and the protistan pathogen qpx (quahog parasite unknown).the immune response of the hard clam (quahog) mercenaria mercenaria following challenge with live bacteria (vibrio alginolyticus) and the protist qpx (quahog parasite unknown) was investigated. the study also compared immune responses following qpx challenge in two different hard clam broodstocks exhibiting different degrees of susceptibility toward this parasite. different immune and stress-related cellular and humoral factors were assessed including general hemocyte parameters (total and diffe ...201222484278
abundance of vibrio cholerae, v. vulnificus, and v. parahaemolyticus in oysters (crassostrea virginica) and clams (mercenaria mercenaria) from long island sound.vibriosis is a leading cause of seafood-associated morbidity and mortality in the united states. typically associated with consumption of raw or undercooked oysters, vibriosis associated with clam consumption is increasingly being reported. however, little is known about the prevalence of vibrio spp. in clams. the objective of this study was to compare the levels of vibrio cholerae, vibrio vulnificus, and vibrio parahaemolyticus in oysters and clams harvested concurrently from long island sound ...201425281373
habitat fragmentation differentially affects trophic levels and alters behavior in a multi-trophic marine system.seagrass, an important subtidal marine ecosystem, is being lost at a rate of 110 km(2) year(-1), leading to fragmented seagrass seascapes. habitat fragmentation is predicted to affect trophic levels differently, with higher trophic levels being more sensitive, stressing the importance of a multi-trophic perspective. utilizing the trophic relationship between the blue crab (callinectes sapidus) and hard clam (mercenaria mercenaria), where adult blue crabs prey on juvenile blue crabs, and juvenile ...201728000022
biotic structure indirectly affects associated prey in a predator-specific manner via changes in the sensory environment.indirect effects, which can be either positive or negative, may be important in areas containing biotic structure, because such structure can provide refuge and habitat, produce additional sensory cues that may attract predators, and modify the sensory landscape in which predator-prey interactions occur. to determine the indirect effects of biotic structure on prey populations, we assessed predation on patches of hard clams (mercenaria mercenaria) by large odor-mediated blue crab (callinectes sa ...201322821422
acute effects of non-weathered and weathered crude oil and dispersant associated with the deepwater horizon incident on the development of marine bivalve and echinoderm larvae.acute toxicity tests (48-96-h duration) were conducted with larvae of 2 echinoderm species (strongylocentrotus purpuratus and dendraster excentricus) and 4 bivalve mollusk species (crassostrea virginica, crassostrea gigas, mytilus galloprovincialis, and mercenaria mercenaria). developing larvae were exposed to water-accommodated fractions (wafs) and chemically enhanced water-accommodated fractions (cewafs) of fresh and weathered oils collected from the gulf of mexico during the deepwater horizon ...201626749266
in vitro interactions between several species of harmful algae and haemocytes of bivalve molluscs.harmful algal blooms (habs) can have both lethal and sublethal impacts on shellfish. to understand the possible roles of haemocytes in bivalve immune responses to habs and how the algae are affected by these cells (haemocytes), in vitro tests between cultured harmful algal species and haemocytes of the northern quahog (= hard clam) mercenaria mercenaria, the soft-shell clam mya arenaria, the eastern and pacific oysters crassostrea virginica and crassostrea gigas and the manila clam ruditapes phi ...201121340660
mollusc larval shell formation: amorphous calcium carbonate is a precursor phase for aragonite.the larval shells of the marine bivalves mercenaria mercenaria and crassostrea gigas are investigated by polarized light microscopy, infrared spectroscopy, raman imaging spectroscopy, and scanning electron microscopy. both species contain similar shell ultrastructures. we show that larval shells contain amorphous calcium carbonate (acc), in addition to aragonite. the aragonite is much less crystalline than non-biogenic aragonite. we further show that the initially deposited mineral phase is pred ...200212486808
nitrogen extraction potential of wild and cultured bivalves harvested from nearshore waters of cape cod, nitrogen entering coastal waters continues to be an issue, much attention has been generated to identify potential options that may help alleviate this stressor to estuaries, including the propagation of bivalves to remove excess nitrogen. oysters (crassostrea virginica) and quahogs (mercenaria mercenaria) from numerous cape cod, ma, (usa) sources were analyzed for nitrogen content stored in tissues that would represent a net removal of nitrogen from a water body if harvested. results showed ...201728065550
effects of intermittent hypoxia on oxidative stress and protein degradation in molluscan mitochondria.oxygen fluctuations represent a common stressor in estuarine and intertidal environments and can compromise the mitochondrial integrity and function in marine organisms. we assessed the role of mitochondrial protection mechanisms (atp-dependent and -independent mitochondrial proteases, and antioxidants) in tolerance to intermittent hypoxia or anoxia in three species of marine bivalves: hypoxia-tolerant hard clams (mercenaria mercenaria) and oysters (crassostrea virginica), and a hypoxia-sensitiv ...201627655555
interactive effects of copper exposure and environmental hypercapnia on immune functions of marine bivalves crassostrea virginica and mercenaria mercenaria.estuarine organisms such as bivalves are commonly exposed to trace metals such as copper (cu) and hypercapnia (elevated co2 levels) in their habitats, which may affect their physiology and immune function. this study investigated the combined effects of elevated co2 levels (∼800-2000 μatm pco2, such as predicted by the near-future scenarios of global climate change) and cu (50 μg l(-1)) on immune functions of the sediment dwelling hard clams mercenaria mercenaria and an epifaunal bivalve, the ea ...201626700170
effects of environmental hypercapnia and metal (cd and cu) exposure on acid-base and metal homeostasis of marine bivalves.elevated co2 levels reduce seawater ph and may affect bioavailability of trace metals in estuaries. we studied the interactive effects of common metal pollutants (50 μg l(-1) cd or cu) and pco2 (~395, 800 and 2000 μatm) on metal levels, intracellular ph, expression of metal binding proteins and stress biomarkers in estuarine bivalves crassostrea virginica (oysters) and mercenaria mercenaria (hard clams). cd (but not cu or hypercapnia) exposure affected the acid-base balance of hemocytes resultin ...201526008775
effects of the red tide dinoflagellate, karenia brevis, on early development of the eastern oyster crassostrea virginica and northern quahog mercenaria mercenaria.the brevetoxin-producing dinoflagellate, karenia brevis, adversely affects many shellfish species including the commercially and ecologically important bivalve molluscs, the northern quahog (=hard clam) mercenaria mercenaria and eastern oyster crassostrea virginica, in the gulf of mexico, usa. this study assessed the effects of exposure of these bivalves to k. brevis during their early development. in separate experiments, embryos of 2-4 cell stage of m. mercenaria and c. virginica were exposed ...201425046170
a non-native prey mediates the effects of a shared predator on an ecosystem service.non-native species can alter ecosystem functions performed by native species often by displacing influential native species. however, little is known about how ecosystem functions may be modified by trait-mediated indirect effects of non-native species. oysters and other reef-associated filter feeders enhance water quality by controlling nutrients and contaminants in many estuarine environments. however, this ecosystem service may be mitigated by predation, competition, or other species interact ...201424718023
immunomodulation by the interactive effects of cadmium and hypercapnia in marine bivalves crassostrea virginica and mercenaria mercenaria.estuarine organisms are exposed to multiple stressors including large fluctuations in partial pressure of carbon dioxide (p2co) and concentrations of trace metals such as cadmium (cd) that can affect their survival and fitness. ocean acidification due to the increasing atmospheric (p2co) leads to a decrease in ph and shifts in the carbonate chemistry of seawater which can change bioavailability and toxicity of metals. we studied the interactive effects of (p2co) and cd exposure on metal levels, ...201424594010
interactive effects of co₂ and trace metals on the proteasome activity and cellular stress response of marine bivalves crassostrea virginica and mercenaria mercenaria.increased anthropogenic emission of co2 changes the carbonate chemistry and decreases the ph of the ocean. this can affect the speciation and the bioavailability of metals in polluted habitats such as estuaries. however, the effects of acidification on metal accumulation and stress response in estuarine organisms including bivalves are poorly understood. we studied the interactive effects of co2 and two common metal pollutants, copper (cu) and cadmium (cd), on metal accumulation, intracellular a ...201424572072
interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased co2 (low ph), are less understood. toxicity was assessed at 4 and 21 days for larval and juvenile stages of the eastern oyster, crassostrea virginica, and the ha ...201424531857
physiological response and resilience of early life-stage eastern oysters (crassostrea virginica) to past, present and future ocean acidification.the eastern oyster, crassostrea virginica (gmelin, 1791), is the second most valuable bivalve fishery in the usa and is sensitive to high levels of partial pressure of co2 (pco2). here we present experiments that comprehensively examined how the ocean's past, present and projected (21st and 22nd centuries) co2 concentrations impact the growth and physiology of larval stages of c. virginica. crassostrea virginica larvae grown in present-day pco2 concentrations (380 μatm) displayed higher growth a ...201427293625
interactive effects of ph and metals on mitochondrial functions of intertidal bivalves crassostrea virginica and mercenaria mercenaria.intertidal bivalves experience broad fluctuations of environmental temperature, ph and oxygen content which could change their intracellular ph. they are also exposed to trace metals such as cadmium (cd) and copper (cu) that accumulate in their tissues and may negatively affect mitochondrial functions and bioenergetics. we determined the interactive effects of ph and trace metals (25 μm cd or cu) on mitochondrial functions (including respiration and membrane potentials in both adp-stimulated (st ...201324211794
interactive effects of elevated temperature and co2 levels on energy metabolism and biomineralization of marine bivalves crassostrea virginica and mercenaria mercenaria.the continuing increase of carbon dioxide (co2) levels in the atmosphere leads to increases in global temperatures and partial pressure of co2 (pco2) in surface waters, causing ocean acidification. these changes are especially pronounced in shallow coastal and estuarine waters and are expected to significantly affect marine calcifiers including bivalves that are ecosystem engineers in estuarine and coastal communities. to elucidate potential effects of higher temperatures and pco2 on physiology ...201323707887
bioaccumulation and depuration of brevetoxins in the eastern oyster (crassostrea virginica) and the northern quahog (= hard clam, mercenaria mercenaria).the eastern oyster (crassostrea virginica) and northern quahog (= hard clam, mercenaria mercenaria) are two species of economic and ecological significance in east coast waters of the united states and the gulf of mexico. commercial industries for these species, especially within the state of florida, are significant. the current study was undertaken to build upon the already established body of knowledge surrounding effects of the toxic dinoflagellate karenia brevis on shellfish, to provide an ...201323419594
interactive effects of elevated temperature and co(2) levels on metabolism and oxidative stress in two common marine bivalves (crassostrea virginica and mercenaria mercenaria).marine bivalves such as the hard shell clams mercenaria mercenaria and eastern oysters crassostrea virginica are affected by multiple stressors, including fluctuations in temperature and co2 levels in estuaries, and these stresses are expected to be exacerbated by ongoing global climate change. hypercapnia (elevated co2 levels) and temperature stress can affect survival, growth and development of marine bivalves, but the cellular mechanisms of these effects are not yet fully understood. in this ...201323319162
biosorption of thorium on the external shell surface of bivalve mollusks: the role of shell surface microtopography.external shell surface (ess) of bivalve mollusks is known to adsorb various metals dissolved in ambient water in high concentration. it is hypothesized here that the surface microtopography of the thin organic coating layer, periostracum, or calcareous shell (if periostracum was destroyed) plays a major role in the adsorption of actinides on ess. thorium (natural alpha-emitter) was used in short-term biosorption experiment with shell fragments of five bivalve mollusks. after a 72 h exposure to t ...201222154000
effects of elevated temperature and carbon dioxide on the growth and survival of larvae and juveniles of three species of northwest atlantic bivalves.rising co(2) concentrations and water temperatures this century are likely to have transformative effects on many coastal marine organisms. here, we compared the responses of two life history stages (larval, juvenile) of three species of calcifying bivalves (mercenaria mercenaria, crassostrea virginica, and argopecten irradians) to temperatures (24 and 28°c) and co(2) concentrations (∼250, 390, and 750 ppm) representative of past, present, and future summer conditions in temperate estuaries. res ...201122066018
comparison of methods for evaluating acute and chronic toxicity in marine sediments.sublethal test methods are being used with increasing frequency to measure sediment toxicity, but little is known about the relative sensitivity of these tests compared to the more commonly used acute tests. the present study was conducted to compare the sensitivity of several acute and sublethal methods and to investigate their correlations with sediment chemistry and benthic community condition. six sublethal methods (amphipod: leptocheirus plumulosus survival, growth, and reproduction; polych ...200818333680
oxidative stress and expression of chaperones in aging mollusks.the mechanisms of aging are not well understood in animals with continuous growth such as fish, reptiles, amphibians and numerous invertebrates, including mollusks. we studied the effects of age on oxidative stress, cellular defense mechanisms (including two major antioxidant enzymes, superoxide dismutase (sod) and catalase), and molecular chaperones in two mollusks--eastern oysters crassostrea virginica and hard clams mercenaria mercenaria. in order to detect the age-related changes in these pa ...200818296092
comparative effects of the toxic dinoflagellate karenia brevis on clearance rates in juveniles of four bivalve molluscs from florida, usa.the effects of karenia brevis (gymnodiniales, gymnodiniaceae) on the feeding activity of juveniles of four species of bivalve mollusc were examined in the laboratory to assess the potential impacts on these important shellfish populations from florida. clearance rates were determined under short-term (one hour) static and long-term (two days) flow-through conditions using both whole and lysed cultures of k. brevis. under short-term conditions, the bay scallop, argopecten irradians, was the most ...200717182073
effects of the dinoflagellate karenia brevis on larval development in three species of bivalve mollusc from florida.the effects of karenia brevis (wilson clone) on larval survival and development of the northern quahog, mercenaria mercenaria, eastern oyster, crassostrea virginica and bay scallop, argopecten irradians, were studied in the laboratory. larvae were exposed to cultures of whole and lysed cells, with mean total brevetoxin concentrations of 53.8 and 68.9 microgl(-1), respectively. survival of early (3-day-old) larvae was generally over 85% for all shellfish species at k. brevis densities of 100 cell ...200616814341
the effects of the contemporary-use insecticide (fipronil) in an estuarine examine the effects of environmentally realistic fipronil concentrations on estuarine ecosystems, replicated mesocosms containing intact marsh plots and seawater were exposed to three treatments of fipronil (150, 355, and 5000 ng/l) and a control. juvenile fish (cyprinidon variegatus), juvenile clams (mercenaria mercenaria), oysters (crassostrea virginica), and grass shrimp (palaemonetes pugio) were added prior to fipronil in an effort to quantify survival, growth, and the persistence of toxi ...200415261399
detection of oxidative dna damage in isolated marine bivalve hemocytes using the comet assay and formamidopyrimidine glycosylase (fpg).organisms in polluted areas can be exposed to complex mixtures of chemicals; however, exposure to genotoxic contaminants can be particularly devastating. dna damage can lead to necrosis, apoptosis, or heritable mutations, and therefore has the potential to impact populations as well as individuals. single cell gel electrophoresis (the comet assay) is a simple and sensitive technique used to examine dna damage in single cells. the lesion-specific dna repair enzyme formamidopyrimidine glycoslyase ...200314644349
flow cytometric comparison of haemocytes from three species of bivalve molluscs.haemocyte subpopulations from three bivalve species (the clams ruditapes philippinarum and mercenaria mercenaria and the oyster, crassostrea virginica) were characterised using light-scatter flow cytometry and a standard set of methods. two parameter (forward and side scatter) plots for the three species were very similar and resembled plots for mammalian white blood cells. two haemocyte groups (granulocytes and agranulocytes) were found in both the haemolymph and the extrapallial fluid of the c ...200212400864
influences of subzero thermal acclimation on mitochondrial membrane composition of temperate zone marine bivalve mollusks.the phospholipid and phospholipid fatty acid composition of gill mitochondrial membranes from two temperate zone marine bivalve mollusks, the quahog, mercenaria mercenaria, and the american oyster, crassostrea virginica, were examined after acclimation to 12 and -1 degree c. cardiolipin (cl) was the only phospholipid with proportions altered upon acclimation to -1 degree c, increasing 188% in the mitochondrial membranes of m. mercenaria. although the ratio of bilayer stabilizing to destabilizing ...199910188598
hemocyte-derived reactive oxygen intermediate production in four bivalve mollusks.luminol-dependent chemiluminescence (ldcl) and nitroblue tetrazolium (nbt) reduction assays have been used to measure reactive oxygen intermediate (roi) production by oyster (crassostrea virginica) hemocytes, as well as roi modulation caused by disease or exposure to environmental toxicants. however, roi responses measured by these tests apparently vary considerably among other bivalve species. in all species tested, unstimulated hemocytes produced small quantities of rois. in c. virginica and g ...20118082818
immunohistochemical localization and radioenzymatic measurements of serotonin (5-hydroxytryptamine) in hearts of aplysia and several bivalve mollusks.serotonin immunoreactivity was localized in hearts of the opisthobranch gastropod, aplysia californica (sea hare) and several species of bivalve mollusks, the heterodonts, mercenaria mercenaria (quahog or cherry stone clam), protothaca staminea (little neck clam), and the pteriomorphs, hinnites multirugosus (rock scallop), crassostrea virginica (eastern oyster), mytilus edulis (eastern mussel), and geukensia demissa (ribbed mussel). in addition, serotonin was assayed in the ventricles, auricles ...19921423510
acute toxicity of tributyltin chloride to embryos and larvae of two bivalve mollusks, crassostrea virginica and mercenaria mercenaria. 19873440138
subcellular distribution of aminotransferases, and pyruvate branch point enzymes in gill tissue from four bivalves.aspartate aminotransferase (aat), alanine aminotransferase (alat), malic enzyme (me), malate dehydrogenase (mdh), pyruvate kinase (pk), and phosphoenolpyruvate carboxykinase (pepck) activities in cytosolic and mitochondrial fractions of gill tissue from modiolus demissus (ribbed mussel), mytilus edulis (sea mussel), crassostrea virginica (oyster) and mercenaria mercenaria (quahog) were determined using enzyme assay and starch gel electrophoresis combined with subcellular fractionation. aat showe ...19854053567
competitive inhibition by dimethylsulfoxide of molluscan and vertebrate acetylcholinesterase.anticholinesterase-like effects of dimethylsulfoxide (dmso) were demonstrated on a variety of invertebrate muscles. the excitatory effects of acetylcholine (ach) on the isolated preparations of the geukensia demissa heart and anterior byssus retractor muscle (abrm), and of the busycon contrarium radula protractor muscle, were potentiated by dmso (1-5 microliters/ml; 1 microliter/ml = 14 mm). the negative chronotropic effects of ach, but not of 4-ketoamyltrimethylammonium, were potentiated by dms ...19836830611
polychlorinated biphenyls in clams and oysters from new bedford harbor, massachusetts, march 1978.polychlorinated biphenyl (pcb) concentrations in clams (mercenaria mercenaria) and oysters (crassostrea virginica) from 17 stations of the western and new bedford harbor areas of buzzards bay, massachusetts, clearly show that the new bedford harbor area is severely polluted. up to 5 ppm pcbs (dry weight) were found in shellfish tissue. the most likely sources of the pcbs are chronic releases from two electrical component manufacturers in new bedford. close proximity of the shellfish to the sourc ...19816817293
three types of acetylcholine response in bivalve heart muscle cells.1. the acetylcholine (ach) responses of cardiac muscle cells from three species of bivalves were studied by intracellular recording and ach ionophoresis. heart muscle contraction was abolished by bathing in artificial sea water in which mn(2+) had been substituted for ca(2+).2. three different types of membrane potential changes were observed in response to ach pulses: a slow hyperpolarization in the clam mercenaria mercenaria, a rapid depolarization which was sometimes followed by a slower hype ...19807381787
elapid alpha-toxins have no effect on the cholinergic responses of bivalve myocardia.elapid alpha-toxins (alpha-bungarotoxin, alpha-cobratoxin and crude bungarus caeruleus venom) do not affect the myocardial nicotinic ach receptors of the following bivalve molluscs: mercenaria mercenaria, chione cancellata, mya arenaria, mytilus edulis, rangia cuneata and crassostrea virginica.1978729727
beta-glucuronidase in the serum and hemolymph cells of mercenaria mercenaria and crassostrea virginica (mollusca: pelecypoda). 19761245743
lysosomal and other enzymes in the hemolymph of crassostrea virginica and mercenaria mercenaria. 19751183196
a quantitative study of phagocytosis by hemolymph cells of the pelecypods crassostrea virginica and mercenaria mercenaria. 19751117165
the inorganic composition of molluscan extrapallial fluid.the inorganic composition of the extrapallial fluids of mercenaria mercenaria, mytilus edulis and crassostrea virginica was significantly different from sea water. calcium was the principal ion bound in the extrapallial fluids. this binding was accomplished by a non-dialyzable component that appeared to be a glycoprotein.197228368702
muscular alteration of gill geometry in vitro: implications for bivalve pumping bivalves, water-pumping potential is determined both by ciliary activity and by the geometry of the system of passageways that acts as a conduit for water flow. smooth muscles intrinsic to the gills of eulamellibranch bivalves possess the anatomical organization needed to regulate the dimensions of these water passageways. the tone of these muscles can be controlled experimentally using excitatory neurotransmitters to elicit muscle contraction and by removing ca++ from the ringer's solution t ...200111249214
skeletal matrices, muci, and the origin of invertebrate calcification.the sudden appearance of calcified skeletons among many different invertebrate taxa at the precambrian-cambrian transition may have required minor reorganization of preexisting secretory functions. in particular, features of the skeletal organic matrix responsible for regulating crystal growth by inhibition may be derived from mucous epithelial excretions. the latter would have prevented spontaneous calcium carbonate overcrusting of soft tissues exposed to the highly supersaturated late proteroz ...199611607630
Displaying items 1 - 95 of 95