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stress-induced catecholamine changes in the hemolymph of the oyster crassostrea gigas.the stress response is a series of coordinated physiological reactions increasing an organism's capacity to maintain homeostasis in the presence of threatening agents. this fundamental process is known to involve hormonal signaling to rapidly modulate key physiological functions in vertebrates, but data are lacking concerning neuroendocrine responses to stress in invertebrates. the present study examined circulating catecholamine (ca) responses to stress in oysters. mechanical disturbances (cons ...200111316423
evidence for a form of adrenergic response to stress in the mollusc crassostrea gigas.catecholamines and pro-opiomelanocortin (pomc)-derived peptides, some of the central regulators of the stress-response systems of vertebrates, are also present in invertebrates. however, studies are needed to determine how these hormones participate in the organisation of neuroendocrine stress-response axes in invertebrates. our present work provides evidence for the presence of an adrenergic stress-response system in the oyster crassostrea gigas. noradrenaline and dopamine are released into the ...200111249835
[biological quality of seawater evaluated in situ with embryo-larval test of crassostrea gigas and mytilus galloprovincialis].embryos and larvae of bivalves are frequently used in marine ecotoxicology for the purpose of assessing seawater quality, because they are very sensitive to pollutants and provide rapid responses. laboratory studies, however, cannot accurately simulate natural conditions. we conducted bivalve embryo-larval studies in situ at the marina of arcachon (south-west french atlantic coast), in order to assess 'biological quality' of the water. one experiment conducted in winter 1999 (temperatures of 10 ...200111803816
noradrenaline modulates hemocyte reactive oxygen species production via beta-adrenergic receptors in the oyster crassostrea gigas.catecholamines (ca) are known to be present in the microenvironment of molluscan immunocytes. in the present study, experiments were conducted to determine the effects of noradrenaline (na), the principal ca circulating in bivalve hemolymph, on the luminol-dependent chemiluminescence (cl) of oyster crassostrea gigas hemocytes. results show that na had a dose-dependent inhibitory effect on the cl-response at the physiological concentration of 0.1 microm and above. the alpha-adrenoceptor agonist p ...200111246068
a centromeric satellite sequence in the pacific oyster (crassostrea gigas thunberg) identified by fluorescence in situ hybridization.a highly repetitive satellite sequence was previously identified in the pacific oyster crassostrea gigas thunberg. the sequence has 168 bp per unit, present in tandem repeats, and accounts for 1% to 4% of the genome. we studied the chromosomal location of this satellite sequence by fluorescence in situ hybridization (fish). a probe was made by polymerase chain reaction and incorporation of digoxigenin-11-dutp. hybridization was detected with fluorescein-labeled antidigoxigenin antibodies. fish s ...200114961342
microsatellite analysis of 6-hour-old embryos reveals no preferential intraspecific fertilization between cupped oysters crassostrea gigas and crassostrea angulata.experimental examination of reproductive isolation is the first step in understanding hybridization processes. here, we studied preferential fertilization between 2 cupped oyster taxa, crassostrea angulata and crassostrea gigas, as a potential prezygotic reproductive isolation. early examination of sperm competition is now possible by molecular analysis of oyster embryos. this avoids the confounding effect of differential mortality during the larval stage. six hundred embryos were sampled from 2 ...200114961337
a review of gymnophalloides seoi (digenea: gymnophallidae) and human infections in the republic of korea.studies on gymnophalloides seoi (digenea: gymnophallidae) and human infections are briefly reviewed. this minute intestinal fluke was first discovered from a korean woman suffering from acute pancreatitis and gastrointestinal troubles. it was described as a new species by lee, chai and hong in 1993. the southwestern coastal village where the patient resided was found to be a highly endemic area, and additional endemic areas have been identified. the parasite is very small, 0.33-0.50 mm long and ...200111441510
transcript analysis of the genes encoding aminopeptidase n and alanine aminotransferase, two enzymes involved in protein turnover, in the pacific oyster, crassostrea gigas.molecular probes have been developed to detect aminopeptidase n (apn) and alanine aminotransferase (alat) transcripts in the pacific oyster crassostrea gigas. degenerate primers were designed using apn and alat sequences stored in the embl database. amplification of c. gigas genomic dna using these primers resulted in amplification of a 344-bp apn fragment and a 530-bp alanine aminotransferase fragment. the deduced amino acid sequence of the apn fragment displayed 75 and 73% identities with sequ ...200111250541
evidence for interspecies transmission of oyster herpesvirus in marine bivalves.since 1991, numerous herpesvirus infections associated with high mortality have been reported around the world in various marine bivalve species. in order to determine whether these infections are due to ostreid herpesvirus-1 (oshv1), a previously characterized pathogen of the japanese oyster (crassostrea gigas), pcr analysis was carried out on 30 samples of larvae collected from four bivalve species (c. gigas, ostrea edulis, ruditapes decussatus and ruditapes philippinarum), most exhibiting mor ...200111257192
in vitro production of peroxynitrite by haemocytes from marine bivalves: c-elisa determination of 3-nitrotyrosine level in plasma proteins from mytilus galloprovincialis and crassostrea gigas.peroxynitrite is increasingly proposed as a contributor to defence system in marine bivalve. it can be formed by combination of superoxide and nitric oxide, and can react with tyrosine residues of proteins giving rise to 3-nitrotyrosine.200111231884
determination of cadmium partitioning in microalgae and oysters: contribution to the assessment of trophic transfer.alternative methodologies have been applied to the study of cadmium transfer in a food chain: water, microalgae (skeletonema costatum and tetraselmis suecica), oysters (crassostrea gigas). the potential bioavailability of cd in organisms was assessed through partitioning at the cell or tissue levels, and the predictive value of this method was evaluated by determining directly the metal transfer in an experimental food chain model. cd concentrations were lower in s. costatum than t. suecica, in ...200111243323
determination of total metals in cultivated oysters (crassostrea gigas) from the northwest coast of mexico by microwave digestion and atomic absorption spectrometry.bivalves such as oysters often accumulate heavy metals, and therefore can be used to monitor changes of pollutant concentrations in the environment. cultivated oysters from the northwest coast of mexico are widely used for human consumption and thus have an important commercial value. information was gathered on the concentration of these elements in oysters (crassostrea gigas) cultivated on the coast of sonora. oysters were randomly collected from april to october 1997, from 6 different locatio ...200111767161
genetic manipulations in aquaculture: a review of stock improvement by classical and modern technologies.the aim of this review was to highlight the extent to which the genetic technologies are implemented by the aquaculture industry. the review shows that some of the modern genetic technologies are already extensively applied by the diverse aquaculture industries, though not to the same extent for all important aquacultured species (according to fao 1998 figures). some species (common carp, atlantic salmon, rainbow trout, channel catfish, nile tilapia, and the pacific oyster) received concentrated ...200111841164
ultrastructure of mikrocytos mackini, the cause of denman island disease in oysters crassostrea spp. and ostrea spp. in british columbia, canada.an ultrastructural study was carried out on mikrocytos mackini, the cause of denman island disease in pacific oysters crassostrea gigas in western canada. three forms were identified, quiescent cells (qc), vesicular cells (vc) and endosomal cells (ec). qc occurred in the vesicular connective tissue (vct), haemocytes (hyalinocytes), adductor and heart myocytes, and extracellularly. they had a central round to ovoid nucleus, < 7 cisternae of inactive nuclear membrane-bound golgi, few vesicles and ...200111558731
a vibrio splendidus strain is associated with summer mortality of juvenile oysters crassostrea gigas in the bay of morlaix (north brittany, france).juvenile oysters crassostrea gigas cultured in the bay of morlaix (france) have suffered unexplained summer mortalities for over a decade. in the present study, we tested the hypothesis that a bacterial pathogen could be responsible for this phenomenon. a first attempt failed to isolate a bacterial pathogen from moribund or weak oysters. only non-pathogenic, probably opportunistic, bacteria were isolated. as an alternative approach, we focused on oysters presenting reduced stress-response capaci ...200111678229
impact of the copepod mytilicola orientalis on the pacific oyster crassostrea gigas in ireland.infections of a population of crassostrea gigas by the copepod mytilicola orientalis were examined at an oyster growing site at dungarvan, county waterford, ireland. twenty-one samples, each consisting of 20 to 30 oysters have been examined over 2 yr. condition, sex, reproductive stage, length, weight, glycogen content and other parasite burdens of the oysters were examined in relation to the degree of infection of m. orientalis; 14.38% of oysters were infested. mean abundance was 0.6 oyster(-1) ...200111775796
response of haemocyte lysosomes to bacterial inoculation in the oysters ostrea edulis l. and crassostrea gigas (thunberg) and the scallop pecten maximus (l).data are presented that demonstrate the application of the neutral red retention assay (nrr) to monitor the effects of a bacterial inoculation on the haemocyte lysosomes of the european flat oyster ostrea edulis, pacific oyster crassostrea gigas and scallop pecten maximus. bivalves were acclimated to three temperature regimes (5, 15 and 25 degrees c), at constant salinity for 7 days in the laboratory. once baseline responses to acclimation temperature had been established, the effects of an in v ...200111308076
stress and stress-induced neuroendocrine changes increase the susceptibility of juvenile oysters (crassostrea gigas) to vibrio splendidus.oysters are permanently exposed to various microbes, and their defense system is continuously solicited to prevent accumulation of invading and pathogenic organisms. therefore, impairment of the animal's defense system usually results in mass mortalities in cultured oyster stocks or increased bacterial loads in food products intended for human consumption. in the present study, experiments were conducted to examine the effects of stress on the juvenile oyster's resistance to the oyster pathogen ...200111319116
toxicity to bivalve hemocytes of pathogenic vibrio cytoplasmic extract.using a chemiluminescence (cl) test, it had been previously demonstrated that vibrio pectenicida, which is pathogenic to pecten maximus larvae, was able to inhibit completely the cl activity of p. maximus hemocytes and partially inhibit those of crassostrea gigas. conversely, a vibrio sp. strain, s322, pathogenic to c. gigas larvae was more active in reducing the cl activity of oyster hemocytes than of scallop hemocytes. using this same cl biotest, v. pectenicida and s322 cytoplasmic extracts we ...200111356051
french scallops: a new host for ostreid herpesvirus-1.sporadic high mortalities were reported among larval french scallops (pecten maximus). electron microscopy of moribund larvae revealed particles with the characteristics of a herpesvirus in association with cellular lesions. pcr and dna sequencing showed that the virus is a variant of ostreid herpesvirus-1 that has already been described in clams and oysters. this is the first description of a herpesvirus infection of a scallop species. the virus was transmitted successfully from an extract of i ...200111883198
cdna cloning and molecular identification of the major oyster allergen from the pacific oyster crassostrea gigas.shellfish is one of the most common food allergens. despite the recent cloning and molecular identification of the major heat stable crustacean allergens in shrimp, lobster and crab, there have been no similar studies on molluscs to which a significant portion of populations allergic to shellfish are also hypersensitive. recent biochemical evidence suggests that tropomyosin is also an allergen in molluscs, but data on the molecular cloning, nucleotide sequencing, expression and ige binding to mo ...200111529900
kinetics of metal elimination in oysters from a contaminated estuary.in oysters crassostrea gigas translocated from a metal-enriched estuary (gironde, france) to a comparatively clean site, the bay of bourgneuf (france), cd, cu and zn concentrations were determined monthly in the whole soft tissues, or in different fractions (cytosolic or insoluble) of gills and digestive glands. in all cases, the concentrations of all of the three metals decreased logarithmically and half-lives were always shortest for cd (86-251 days). after 4 months, the cd concentration had b ...200211912053
characteristics of trophic transfer of polychlorinated biphenyls in marine organisms in incheon north harbor, korea.the trophic transfer of polychlorinated biphenyls (pcbs) was characterized for zooplankton (primarily paracalanus spp. and acartia spp.), pacific oyster (crassostrea gigas), shore crab (hemigrapsus penicillatus), and goby (acanthogobius hasta) in the aquatic system of incheon north harbor, korea. the congener pattern in the species was clearly divided by the main pcb uptake route. compared with zooplankton and oyster, the fraction of heavier homologues increased in crab and goby that take pcbs f ...200211951959
immunochemical quantification of metallothioneins in marine mollusks: characterization of a metal exposure bioindicator.a recombinant metallothionein cgmt1, from the pacific oyster crassostrea gigas, was synthesized and used as antigen in the development of antibodies and a specific enzyme-linked immunosorbent assay (elisa). the elisa showed that rabbit anti-cgmt1 igg reacted with purified cgmt1 and mts from other marine bivalves, indicating its suitability as a reagent to quantify mts and for monitoring of metal contamination in field animals. application of this assay to tissues excised from metal exposed c. gi ...200212013122
[characterization of pathogenic bacteria of the cupped oyster crassostrea gigas].the french mollusc production is mainly based on the pacific cupped oyster, crassostrea gigas. since 1991, outbreaks of mass mortality of juveniles are reported during the summer period. these outbreaks are a major concern of oyster industry. several studies have established given bacterial strains to be pathogenic for bivalve species, including oysters. here we present a study of mortality outbreaks of c. gigas, as initiated in 1995. in a first step, bacterial strains were isolated during mass ...200212017771
protease inhibitors and haemagglutinins associated with resistance to the protozoan parasite, perkinsus marinus, in the pacific oyster, crassostrea gigas.perkinsus marinus is a protozoan responsible for dramatic mortality in the eastern oyster, crassostrea virginica, but not in the pacific oyster, c. gigas. to understand the host-parasite relationship, we inoculated p. marinus trophozoites into the shell cavity of c. gigas and measured, over 2 months, (i) intensity of infection, (ii) protease inhibitory activities against p. marinus proteases and against bovine z-chymotrypsin, (iii) plasma haemagglutinin titre, (iv) plasma protein concentration, ...200212403320
effects of toxic dinoflagellates and toxin biotransformation in bivalves.attempts were made to elucidate the different responses of shellfish to paralytic shellfish poison (psp) and the psp donor alexandrium minutum t1. five species of edible bivalves (crassostrea gigas, meretrix lusoria, mytilus edulis, ruditapes philippinarum, and soletellina diphos) were collected and examined for susceptibility to psp and psp donor. it was determined that all five bivalves had low susceptibility to psp following an intramuscular injection (> 300 mu/20 g). the abnormal effects on ...200212503874
herpes-like virus detection in infected crassostrea gigas spat using dig-labelled probes.an in situ hybridization protocol for detecting the herpes-like virus which infects french pacific oysters, crassostrea gigas, was developed. two dna probes were synthesized by incorporation of digoxigenin 11-dutp during pcr. two oyster herpes-like virus specific primer pairs, a5/a6 and c1/c6, were used. both dig-labelled probes were able to detect 50 pg of herpes-like virus pcr amplified dna in southern blot hybridizations. the probes hybridized with viral dna in paraffin sections of infected c ...200211849678
comparative susceptibility of veliger larvae of four bivalve mollusks to a vibrio alginolyticus strain.the susceptibility of 7 d old veliger larvae of the scallops argopecten ventricosus and nodipecten subnodosus, the penshell atrina maura, and the pacific oyster crassostrea gigas to a pathogenic strain of vibrio alginolyticus was investigated by challenging the larvae with different bacterial concentrations in a semi-static assay. the results indicate that the larvae of the 2 scallop species are more susceptible to the v. alginolyticus strain than those of the oyster and the penshell. signs of t ...200212113308
detection of oyster herpesvirus dna and proteins in asymptomatic crassostrea gigas adults.since 1972, several herpes-like virus infections have been reported among different bivalve species around the world. most of these reports involved larvae or juveniles presenting high mortalities. two case reports of herpes-like viruses concerned adult oysters, crassostrea virginica in usa and ostrea angasi in australia. molecular techniques including pcr and in situ hybridization (ish) have been recently developed to detect the oyster herpesvirus genome. in the present study, 30 pacific oyster ...200211900847
hsp70 expression in thermally stressed ostrea edulis, a commercially important oyster in europe.synthesis of heat shock proteins (hsps) in response to elevated temperatures and other denaturing agents is a common feature of prokaryotic and eukaryotic cells. the heat-induced expression of hsp70 family members in the gills and mantle of ostrea edulis, a highly valued fisheries resource inhabiting primarily estuarine environments, has been studied. o edulis is exposed to a variety of natural and anthropogenic stresses in the environment. two isoforms of about 72 kda and 77 kda were constituti ...200212482201
determination of an arsenosugar in oyster extracts by liquid chromatography-electrospray mass spectrometry and liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic fluorescence spectrometry.hplc-uv-hg-afs analysis of aqueous extracts of oysters (crassostrea gigas) taken from the southwestern atlantic coast of spain showed the presence of arsenite, arsenate, dimethylarsinic acid and an unidentified arsenic peak. subsequent analysis of the oyster samples by lc-electrospray ms and comparison with four standard dimethylarsinoylribosides (arsenosugars), showed that the previously unidentified peak was an arsenosugar (arsenosugar 2). when the arsenosugar in the oyster was quantified usin ...200211827397
cell culture of bivalves: tool for the study of the effects of environmental stressors.spontaneous beating cells can be isolated from the heart of the oyster (crassostrea gigas) and cultured for more than two months. they form adherent contractile networks in culture conditions. they show muscarinic and beta-adrenergic reactivity thus showing that they are functional cardio-myocytes: acetylcholine induced a dose dependent decrease in spontaneous beating rate via an increase in potassium conductance, this effect being blocked by atropine. epinephrine induced a dramatic increase in ...200212064442
p35-sensitive caspases, map kinases and rho modulate beta-adrenergic induction of apoptosis in mollusc immune cells.apoptosis is an important mechanism for the preservation of a healthy and balanced immune system in vertebrates. little is known, however, about how apoptotic processes regulate invertebrate immune defenses. in the present study, we show that noradrenaline, a catecholamine produced by the neuroendocrine system and by immune cells in molluscs, is able to induce apoptosis of oyster crassostrea gigas hemocytes. the apoptosis-inducing effect of noradrenaline was mimicked by isoproterenol and blocked ...200211865032
gene structure and expression of cg-alr1, a type i activin-like receptor from the bivalve mollusc crassostrea gigas.members of the transforming growth factor beta superfamily of cell signaling polypeptides have attracted much attention because of their ability, from nematodes to mammals, to control cellular functions that in turn, regulate embryo development and tissue homeostasis (the transforming growth factors betas 95 (1990) 419). to understand the divergent evolution of the structures and functions of the transforming growth factor beta receptors (superfamily) we report here the cloning and characterizat ...200212490320
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
time should be considered in developmental ecotoxicity test.developmental toxicity tests are often used for the hazard assessment of chemicals and environmental media. one of the most widely used is the oyster embryo larval test (oel), in which the development of oyster larvae is arrested at a single fixed time (e.g. 24 or 48 h) of toxic exposure, and the proportion of normal larvae measured. however, a major problem with this conventional approach is the lack of information on temporal trends in development. in this study, pacific oyster crassostrea gig ...200212398372
relationships between contaminant levels in marine sediments and their biological effects on embryos of oysters, crassostrea gigas.abstract-surface sediment samples from 10 coastal locations were analyzed with respect to their physical and chemical characteristics as well as their biological quality. the toxicity of the decanted fresh and freeze-dried sediments and of their elutriates was assessed by bioassays with embryos of the oysters crassostrea gigas. the concentration inhibiting normal embryogenesis in 20% of the larvae (ec20) was used as a measure of toxicity and compared with the physical and chemical properties of ...200212389908
metabolic depression and whole-body response to enforced starvation by crassostrea gigas postlarvae.physiological and biochemical measurements were performed on six oyster (crassostrea gigas) cohorts, in order to: (a) investigate the whole-body response (growth, energy content, metabolic and excretion rates) of 2-week-old postlarvae (spat) to enforced (0-8 days) starvation, and (b) test the potential use of three aerobic enzyme systems as indices of physiological condition. starvation resulted in exponential reduction of postlarval metabolic and excretion rates, as well as a linear decrease in ...200212160873
influences of triploidy, parentage and genetic diversity on growth of the pacific oyster crassostrea gigas reared in contrasting natural environments.an increasing number of hypotheses are being proposed to explain the faster growth potential of triploids in molluscs, including their partial sterility or their higher heterozygosity compared to diploids. triploid advantage however, remains controversial for poorer sites, because of a potential trade-off with survival. these questions were addressed in crassostrea gigas by deploying meiosis ii triploids and their diploid siblings from a single mass spawning of three males and seven females, in ...200212144669
stress-induced immune changes in the oyster crassostrea gigas.information concerning the effect of stress on invertebrate immune functions are scarce. the present study investigated the consequences of a 15-min mechanical disturbance on immune parameters in oysters crassostrea gigas. as indicated by noradrenaline and dopamine measurements, the mechanical disturbance caused a transient state of stress in oysters. the number of circulating hemocytes, the migratory and phagocytic activities and reactive oxygen species production of hemocytes were measured bef ...200211687258
the effects of elutriates from pah and heavy metal polluted sediments on crassostrea gigas (thunberg) embryogenesis, larval growth and bio-accumulation by the larvae of pollutants from sedimentary origin.the release, bio-availability and toxicity of contaminants, when sediments are resuspended have been examined, studying concurrently their effects on the embryogenesis and on the larval growth of the crassostrea gigas larvae and their bio-accumulation in those organisms. three characteristic sediments have been selected (one contaminated by pahs, a second by heavy metals and the last by the both pollutants). the organisms were directly exposed to elutriates obtained from each sediment or fed on ...200212521137
aroma extracts from oyster crassostrea gigas: comparison of two extraction methods.the study of the aroma of oysters is of great economic interest in france because it enables their organoleptic quality to be verified. the aim of this study is to optimize the extraction methods of the volatile compounds of oysters crassostrea gigas in order to obtain an extract with an odor as close as possible to that of the original oysters'. oyster aroma is rarely studied, and its sensory profile has not been investigated to date. two extraction methods were studied: vacuum hydrodistillatio ...200211782198
evidence of a tetradocosahexaenoic cardiolipin in some marine bivalves.separation of phospholipid classes in lipid extracts from the scallop pecten maximus, the pacific oyster crassostrea gigas, and the blue mussel mytilus edulis was conducted using hplc. an isolated polar lipid fraction was found to contain a very high level of dha, up to 80 mol% of the total fa. ms with electrospray ionization in the positive-ion mode, tandem ms (ms-ms) and multidimensional nmr spectroscopy were used to analyze the detailed chemical structure of this polar lipid fraction. the iso ...200212056594
study of atrazine effects on pacific oyster, crassostrea gigas, haemocytes.shellfish farming is an important economic activity around the world. this activity often takes place in areas subjected to various recurring pollutions. the recrudescent use of herbicides in agriculture including atrazine implies pollutant transfer towards aquatic environment in estuarine areas. harmful effects of such substances on animals in marine environment, particularly on cultured bivalves, are poorly documented. bivalve molluscs such as mussels and oysters have been postulated as ideal ...200312570668
quantification of gene transcription and enzyme activity for functionally important proteolytic enzymes during early development in the pacific oyster crassostrea gigas.gene transcripts and enzyme activities were quantified for a selection of functionally important aminopeptidases at 2-day intervals throughout the first 72 days of development in the pacific oyster crassostrea gigas. leucine aminopeptidase (lap) and cathepsin b (cathb) gene transcripts were quantified using fluorogenic ('real time') pcr. lap and cathb gene transcripts were detected at all time points. the proportion of cathb transcripts remained essentially constant and low throughout developmen ...200314602147
some methodological aspects of metallothionein evaluation.the specificity of the methods used for metallothioneins (mts) determination in both field and laboratory studies is crucial to a relevant interpretation of the results. the technique applied in the present study is commonly used, but several potential problems may limit its validity: (i). the stability of the metal-sh links during heating and the possibility of metal exchanges between mts and others compounds; (ii). the presence of heat-stable thiol compounds with high molecular weight or very ...200312507607
impact of atrazine on aneuploidy in pacific oysters, crassostrea gigas.aneuploidy has previously been described and studied in the pacific oyster, crassostrea gigas, and has been shown to be negatively correlated with growth. the present study investigated the effect of atrazine on the level of aneuploidy in this species. crassostrea gigas adults and juveniles were subjected to different concentrations of atrazine representing a peak value found in a polluted environment (46.5 nm) and a value 10 times higher (465 nm). although atrazine did not show any effect on th ...200312503768
molecular characterization of a cdna encoding putative vitellogenin from the pacific oyster crassostrea gigas.to elucidate the molecular mechanisms involved in oogenesis, we applied a differential display method to identify genes whose expression was detected only in ovaries containing oocytes. one of the cdna fragments isolated by mrna differential display was similar in structure to vitellogenin. using this fragment, a full-length cdna encoding putative vitellogenin in the pacific oyster crassostrea gigas was cloned by race (rapid amplification of cdna ends), and its amino acid sequence was deduced. t ...200312560599
immune gene discovery by expressed sequence tags generated from hemocytes of the bacteria-challenged oyster, crassostrea gigas.an expressed sequence tag program was undertaken to isolate genes involved in defense mechanisms of the pacific oyster, crassostrea gigas. putative function could be assigned to 54% of the 1142 sequenced cdnas. we built a public database where all est information are accessible through numerous search profiles (http://www.ifremer.fr/gigasbase). based on sequence similarities we identified 20 genes that may be implicated in immune function. we investigated the expression of four of these genes du ...200312559575
zinc in oysters (crassostrea gigas): chemical characteristics and action during in vitro digestion.to obtain information on the luminal absorption of oyster zinc, the zinc action during an in vitro protease digestion of oysters was examined. more than 90% of the zinc rendered solute at ph 1.3 or 3.0 irrespective of the pepsin digestion. the solute zinc was partially re-precipitated by neutralization, and trypsin digestion did not render the re-precipitated zinc solute. when the pepsin digestion was performed at ph 5.0, the ratio of soluble zinc in trypsin digest decreased. when the trypsin di ...200314974730
phenotypic plasticity of hsp70 and hsp70 gene expression in the pacific oyster (crassostrea gigas): implications for thermal limits and induction of thermal tolerance.pacific oysters, crassostrea gigas, living at a range of tidal heights, routinely encounter large seasonal fluctuations in temperature. we demonstrate that the thermal limits of oysters are relatively plastic, and that these limits are correlated with changes in the expression of one family of heat-shock proteins (hsp70). oysters were cultured in the intertidal zone, at two tidal heights, and monitored for changes in expression of cognate (hsc) and inducible (hsp) heat-shock proteins during the ...200314583513
metal concentrations in mussel crenomytilus grayanus and oyster crassostrea gigas in relation to contamination of ambient sediments.the relationship between zn, cu, cd, pb, and ni concentrations in soft tissues of mussels and oysters and those in ambient sediments was examined. the study area was the coastal habitats of the northwestern sea of japan, which has a broad range of contamination due to urban sewage. significant increases of all metals, except ni, were observed in mussel crenomytilus grayanus at concentrations of easily leachable metals in ambient sediments higher than 2, 100, and 800 microg/g for cd, cu, and zn, ...200312705947
assessment of the bioavailability and toxicity of sediment-associated polycyclic aromatic hydrocarbons and heavy metals applied to crassostrea gigas embryos and larvae.sediments represent a vast sink for contaminants in aquatic systems, and may pose a threat to pelagic and benthic organisms. the objective of this research was to determine the bioavailability and toxicity of sediment-associated pahs and heavy metals, using embryos and larvae of the oyster crassostrea gigas, exposed to two sediment fractions: the whole sediment and the elutriate. the percentages of abnormal larvae, the contaminant accumulation and, (in the case of metal contamination), the induc ...200312705922
phenoloxidase activity in larval and juvenile homogenates and adult plasma and haemocytes of bivalve molluscs.phenoloxidase (po) activity was studied in larval and juvenile homogenates and in the plasma and haemocytes of adult crassostrea gigas, argopecten ventricosus, nodipecten subnodosus, and atrina maura. samples were tested for the presence of po activity by incubation with the substrate l-3, 4-dihydroxyphenylalanine using trypsin, alpha-chymotrypsin, laminarin, lipopolysaccharides (lps), and sodium dodecyl sulphate (sds) to elicit activation of prophenoloxidase (propo) system. po activity was not ...200312969649
sources of polychlorinated dibenzo-p-dioxins (pcdds), polychlorinated dibenzofurans (pcdfs), and coplanar polychlorinated biphenyls (co-pcbs), and their bioaccumulation through the marine food web in sendai bay, japan.the concentrations of pcdd/f and co-pcb congeners in seawater, sediment, pacific oyster, japanese anchovy, marbled sole, and japanese flounder samples from sendai bay, japan, were analyzed. the compositions of total pcdd/f and total co-pcb concentrations in sediment and pacific oyster reflected that in seawater--the compositions of total pcdd, pcdf, and co-pcb concentrations were approximately 60, 10, and 30%, respectively. the compositions in japanese anchovy, marbled sole, and japanese flounde ...200312948237
mapk is involved in metaphase i arrest in oyster and mussel oocytes.oocytes of crassostrea gigas and mytilus galloprovincialis are arrested in metaphase i when they are spawned and ready to be fertilized. to investigate the role of map kinase in maintaining metaphase i arrest, oocytes were exposed to the mek inhibitor u0126, and the effects on chromosome behavior and mapk activity were examined by bisbenzimide staining and in immunoblots with anti-phospho mapk antibodies. following treatment with 50 microm u0126, active mapk was undetectable and oocytes resumed ...200312941525
molecular identification and expression of heat shock cognate 70 (hsc70) and heat shock protein 70 (hsp70) genes in the pacific oyster crassostrea gigas.the 70-kda heat shock protein (hsp) family is composed of both environmentally inducible (hsp) and constitutively expressed (hsc) family members. we sequenced 2 genes encoding an hsp70 and an hsc70 in the pacific oyster crassostrea gigas. the cghsc70 gene contained introns, whereas the cghsp70 gene did not. moreover, the corresponding amino acid sequences of the 2 genes presented all the characteristic motifs of the hsp70 family. we also investigated the expression of hsp70 in tissues of oysters ...200312820657
characterization of a tal/scl-like transcription factor in the pacific oyster crassostrea gigas.we have cloned and characterized a cdna encoding cg-tal in the pacific oyster crassostrea gigas. the isolated cdna encodes a 219 amino acids protein that contains the basic helix-loop-helix (bhlh) domain homologous to that of vertebrate and invertebrate tal1/scl. phylogenetic analyses sustained that cg-tal belongs to this family of bhlh transcription factors. northern blot analysis of cg-tal mrna expression in adult oyster tissues indicated that cg-ta1 was specifically expressed in hemocytes, in ...200312818636
geographical, temporal, and species variation of the polyether toxins, azaspiracids, in shellfish.azaspiracid poisoning (azp) is a new toxic syndrome that has caused human intoxications throughout europe following the consumption of mussels (mytilus edulis), harvested in ireland. shellfish intoxication is a consequence of toxin-bearing microalgae in the shellfish food chain, and these studies demonstrated a wide geographic distribution of toxic mussels along the entire western coastal region of ireland. the first identification of azaspiracids in other bivalve mollusks including oysters (cra ...200312901653
effect of a mono-specific algal diet on immune functions in two bivalve species--crassostrea gigas and ruditapes philippinarum.the impact of diets upon the fatty acid composition of haemocyte polar lipids and consequently upon immune parameters has been tested in the oyster crassostrea gigas and the clam ruditapes philippinarum. oysters and clams were fed each of three cultured algae: chaetoceros calcitrans, which is rich in 20:5(n-3) and 20:4(n-6) and poor in 22:6(n-3) fatty acids; t-iso (isochrysis sp.), which is rich in 22:6(n-3) and deficient in 20:5(n-3) and 20:4(n-6); and tetraselmis suecica, which is deficient in ...200312878673
effects of feeding oyster, crassostrea gigas, on serum and liver lipid levels in rats.the effects of feeding dietary and defatted oyster meat on lipid metabolism were investigated in rats by comparing measurements with those of casein and soybean protein. in the first experiment, male rats were fed 0.1% and 1% cholesterol-supplemented diets containing casein, oyster or soybean protein under the same dietary level of protein (20%). the concentrations of serum and liver cholesterol in the oyster group were significantly lower than those in the casein group for both the 0.1% and 1% ...200312887155
measurement of crassostrea gigas hemocyte oxidative metabolism by flow cytometry and the inhibiting capacity of pathogenic vibrios.a flow cytometric method to measure the production of oxidative metabolism products was adapted for use with crassostrea gigas hemocytes. the method is based upon the oxidation, by hydrogen peroxide (h2o2), of intracellular 2',7'-dichlorofluorescin (dcfh) to green-fluorescent dichlorofluorescein. activation of the respiratory burst (rb) was tested using phorbol myristate acetate with no success. by contrast, activation by zymosan particles increased oxidation of dcfh in c. gigas hemocytes, mainl ...200312892744
implication of brevetoxin b1 and pbtx-3 in neurotoxic shellfish poisoning in new zealand by isolation and quantitative determination with liquid chromatography-tandem mass spectrometry.brevetoxin b1 (btx-b1) was isolated from austrovenus stutchburyi following the 1992-1993 outbreak of neurotoxic shellfish poisoning (nsp) in new zealand. we report here the first isolation of pbtx-3 from the same shellfish and the development of a procedure for quantitative determination of pbtx-3 and btx-b1. pbtx-3 was isolated by chromatography on columns of sio2, ods, and lh-20, followed by reverse-phase hplcs. in mass spectrometry (ms) with an electrospray ionization (esi) interface operatin ...200312893066
structure of amylase genes in populations of pacific cupped oyster ( crassostrea gigas): tissue expression and allelic polymorphism.using the previously determined complementary dna sequence of crassostrea gigas amylase (y08370), we designed several oligonucleotide primers and used them with polymerase chain reaction (pcr) technology to characterize oyster amylase gene sequences. two genes encoding 2 different amylases were characterized and sequenced. the 2 genes are similarly organized with 8 exons and 7 introns. intron insertions are found at the same location in the 2 genes. sizes and nucleotide sequences are different f ...200314719164
accumulation of organotin compounds in pacific oysters, crassostrea gigas, collected from aquaculture sites in taiwan.butyltin and phenyltin residues were quantified in pacific oysters (crassostrea gigas), which were collected from several aquaculture sites along the west coast of taiwan during different seasons. butyltin compounds were detected in all of the samples, except in the oysters collected from the wanggung site in november 2002. monophenyltin and diphenyltin compounds were not detected in any of the samples. the average concentrations of monobutyltin, dibutyltin, tributyltin and tetrabutyltin in the ...200312922059
insulin-like system and growth regulation in the pacific oyster crassostrea gigas: hrigf-1 effect on protein synthesis of mantle edge cells and expression of an homologous insulin receptor-related receptor.the involvement of molecules belonging to the insulin/igf family in regulation of growth has been investigated in the pacific oyster crassostrea gigas. in vitro biological effects of human recombinant igf-1 (hrigf-1) on mantle edge cells, involved in oyster shell and soft body growth, were studied over an annual cycle. in mantle edge cells hrigf-1 stimulates protein synthesis of 56+/-5.1% over basal for 10(-10) m in september with in addition a clear dose-effect corresponding to the highest shel ...200313129502
development of novel microsatellite dna markers from the pacific oyster crassostrea gigas.we document the potential of novel microsatellites as a genetic tool in furthering our understanding of the crassostrea gigas genetic structure. from the microsatellite-enriched libraries we constructed, 123 repeat regions that had sufficient sequence information to design polymerase chain reaction primer sets were isolated. from these, 9 primer pairs were screened in a c. gigas population of 67 individuals to evaluate the genetic variability. all but 1 of the 9 loci showed allelic variation (nu ...200314502394
molecular and physiological characterization of an invertebrate homologue of a calcitonin-related receptor.calcitonin is a key hormone involved in the regulation of calcium metabolism in vertebrates. using oligonucleotide primers derived from consensus sequences of vertebrate calcitonin receptors, we have cloned and characterized the first representative of an invertebrate calcitonin receptor from the bivalve mollusc crassostrea gigas. this receptor named cg ct-r exhibits 39% amino acid sequence identity with both human calcitonin and calcitonin gene-related precursor receptors. cg ct-r is expressed ...200314550300
hepatitis a virus detection in oysters (crassostrea gigas) in santa catarina state, brazil, by reverse transcription-polymerase chain reaction.shellfish are readily contaminated with viruses present in water containing sewage because of the concentration effect of filter feeding. hepatitis a virus (hav) is the main cause of acute hepatitis worldwide and may lead to severe illness or even death. it is transmitted through fecal and oral routes and causes widespread endemic and asymptomatic infections in young children. here we describe a method for the detection of hav rna in shellfish involving the extraction of total rna from oyster me ...200312636311
comparison of two microalgal diets. 1. influence on the biochemical and fatty acid compositions of raw oysters (crassostrea gigas).oyster farming in france is a traditional activity. each year, 149 000 tons of oysters are fattened before being sold. more and more oyster farmers supplement the diet of oysters by microalgae to optimize the fattening process and to improve both the growth and flesh quality of oysters. in the present study, oysters were supplemented by two microalgae: skeletonema costatum and tahitian isochrysis clone. the ash, protein, carbohydrate (including glycogen), and lipid contents were analyzed. the gr ...200312643666
comparison of two microalgal diets. 2. influence on odorant composition and organoleptic qualities of raw oysters (crassostrea gigas).oyster farming is of real economic interest in france. oyster farmers attach more and more importance to improving the growth and the quality of their oysters. some fatty acids known to be aroma precursors originate from microalgae such as skeletonema costatum and tahitian isochrysis clone. these microalgae were used to fatten oysters in order to observe their role in the development of oysters' aroma. this study shows that the profile of fatty acids of oysters is influenced by the contribution ...200312643667
isolation and 18s ribosomal dna gene sequences of marteilioides chungmuensis (paramyxea), an ovarian parasite of the pacific oyster crassostrea gigas.to develop sensitive detection techniques with the aim of elucidating the life cycle of marteilioides chungmuensis, an intracellular paramyxean infecting the ovary of the pacific oyster crassostrea gigas, we isolated the parasite at the sporont stage from infected oysters using a freeze-thaw procedure at -20 degrees c and differential centrifugations in discontinuous sucrose and percoll gradients. dna was extracted from the isolated sporonts, and a pcr amplicon of 18s small subunit ribosomal rna ...200312747642
natural water-purification system observed in a shallow coastal lagoon: matsukawa-ura, japan.field surveys and in situ experiments were conducted in the shallow matsukawa-ura in summer to evaluate the biological efficiencies of shallow-water areas for preserving coastal ecosystems. in matsukawa-ura (5.8 km(2)), the suspension-feeding bivalves ruditapes philippinarum and crassostrea gigas were the dominant animals--their total biomasses (wet weight) were estimated to be 3.4 x 10(6) and 2.3 x 10(6) kg, respectively. ulva sp. and zostera marina were the dominant macrophyte species during t ...200312787612
molecular detection of the oyster parasite mikrocytos mackini, and a preliminary phylogenetic analysis.the protistan parasite mikrocytos mackini, the causative agent of denman island disease in the oyster crassostrea gigas in british columbia, canada, is of wide concern because it can infect other oyster species and because its life cycle, mode of transmission, and origins are unknown. pcr and fluorescent in situ hybridization (fish) assays were developed for m. mackini, the pcr assay was validated against standard histopathological diagnosis, and a preliminary phylogenetic analysis of the m. mac ...200312803386
genetic polymorphism and trade-offs in the early life-history strategy of the pacific oyster, crassostrea gigas (thunberg, 1795): a quantitative genetic study.we investigated genetic variability and genetic correlations in early life-history traits of crassostrea gigas. larval survival, larval development rate, size at settlement and metamorphosis success were found to be substantially heritable, whereas larval growth rate and juvenile traits were not. we identified a strong positive genetic correlation between larval development rate and size at settlement, and argue that selection could optimize both age and size at settlement. however, trade-offs, ...200314635840
prevalence and infection intensity of the ovarian parasite marteilioides chungmuensis during an annual reproductive cycle of the oyster crassostrea gigas.the occurrence of marteilioides chungmuensis, a protozoan paramyxean parasite in the reproductive system of the pacific oyster crassostrea gigas, was observed at gosung bay, korea. seasonal variation in gonad development was investigated in a suspended cultured oyster population. gametogenesis began in february and first-spawning was observed between mid and late june when surface water temperature reached 22 to 25 degrees c. spawning activity extended from mid june to late september, with 2 mar ...200314667038
supplementation of perkinsus marinus cultures with host plasma or tissue homogenate enhances their infectivity.the protozoan oyster parasite perkinsus marinus can be cultured in vitro in a variety of media; however, this has been associated with a rapid attenuation of infectivity. supplementation of defined media with products of p. marinus-susceptible (crassostrea virginica) and -tolerant (crassostrea gigas, crassostrea ariakensis) oysters alters proliferation and protease expression profiles and induces differentiation into morphological forms typically seen in vivo. it was not known if attenuation cou ...200414711671
plasticity in resource allocation based life history traits in the pacific oyster, crassostrea gigas. i. spatial variation in food abundance.we investigated the quantitative genetics of plasticity in resource allocation between survival, growth and reproductive effort in crassostrea gigas when food abundance varies spatially. resource allocation shifted from survival to growth and reproductive effort as food abundance increased. an optimality model suggests that this plastic shift may be adaptive. reproductive effort plasticity and mean survival were highly heritable, whereas for growth, both mean and plasticity had low heritability. ...200415009268
cadmium in oysters and scallops: the bc experience.health effects of non-occupational lifetime exposure to cadmium (cd) are of growing concern worldwide. this overview provides some context for the current situation in coastal british columbia, canada, which arose in 1999 from the discovery of problematic residues of cd in farmed pacific oysters (crassostrea gigas). efforts are underway to define cd sources and the geographical and seasonal variation of these cd residues. the recent application by the european community of a 1 microg cd/g (wet w ...200415041066
phylogenetic study and identification of vibrio splendidus-related strains based on gyrb gene sequences.different strains related to vibrio splendidus have been associated with infection of aquatic animals. an epidemiological study of v. splendidus strains associated with crassostrea gigas mortalities demonstrated genetic diversity within this group and suggested its polyphyletic nature. recently 4 species, v. lentus, v. chagasii, v. pomeroyi and v. kanaloae, phenotypically related to v. splendidus, have been described, although biochemical methods do not clearly discriminate species within this g ...200415109135
pathogenicity testing of shellfish hatchery bacterial isolates on pacific oyster crassostrea gigas larvae.bacterial diseases are a major cause of larval mortality in shellfish hatcheries. even with proper sanitation measures, bacterial pathogens cannot be eliminated in all cases. the pathogenicity of bacteria isolated from pacific northwest shellfish hatcheries to pacific oyster crassostrea gigas larvae was investigated. we found 3 highly pathogenic strains and 1 mildly pathogenic strain among 33 isolates tested. these strains appear to be members of the genus vibrio. although there have been many s ...200415109146
ontogenetic variations of hydrolytic enzymes in the pacific oyster crassostrea gigas.occurrence and level of hydrolytic enzymatic activity (proteases, glycosidases, phosphatases, lipases, and esterases) were studied in oocytes, larvae, juveniles, and adult haemolymph of the pacific oyster crassostrea gigas. samples were obtained as oocyte lysate supernatant, larval homogenate supernatant, juvenile homogenate supernatant, haemocyte lysate supernatant, and plasma. the presence of enzymes was demonstrated by colorimetric and lysoplate assay techniques. between stages, significant d ...200415123298
screening of vibrio isolates to develop an experimental infection model in the pacific oyster crassostrea gigas.in an attempt to develop a reproducible experimental model of bacterial infection in crassostrea gigas, oysters taken from very localised sub-populations suffering natural mortality outbreaks were used in cohabitation trials under laboratory conditions. from these trials, a collection of vibrio strains was isolated from moribund and healthy oysters. in a second step, strains were experimentally tested for virulence by means of injection into healthy oysters. this screening revealed a span of vir ...200415212292
two vibrio splendidus related strains collaborate to kill crassostrea gigas: taxonomy and host alterations.for several years, strains phenotypically related to vibrio splendidus have been associated with mortality outbreaks of molluscs. a former study on crassostrea gigas demonstrated the genetic diversity of v. splendidus strains associated with diseased animals. another study suggested that different strains may act in an additive/synergistic way leading to higher c. gigas mortality rates. here, a strain pair (31+32) was characterised at taxonomic and virulence levels. using a polyphasic approach, ...200415648832
the identification of genes from the oyster crassostrea gigas that are differentially expressed in progeny exhibiting opposed susceptibility to summer mortality.summer mortality associated with juveniles of the oyster crassostrea gigas is probably the result of a complex interaction between the host, pathogens and environmental factors. genetic variability in the host appears to be a major determinant in its sensitivity to summer mortality. previously, divergent selection criteria based on summer survival have been applied to produce oyster families with resistant and susceptible progeny. in this paper, we describe the use of suppression subtractive hyb ...200415563847
the effects of decanted sediments on embryogenesis in oysters (crassostrea gigas).sediments act as sinks for contaminants of natural and anthropogenic origin, constituting a risk to the living organisms. in this study, sediments were collected from three sites on the coast of southwest france. the objective of this research was to determine the effects of sediments on embryonic development of bivalves and to identify precisely when the contaminants affect the embryos and induce them to develop in an abnormal way. the toxicity of decanted sediments and overlying waters were as ...200415230318
comparative concentrations of brevetoxins pbtx-2, pbtx-3, btx-b1 and btx-b5 in cockle, austrovenus stutchburyi, greenshell mussel, perna canaliculus, and pacific oyster, crassostrea gigas, involved neurotoxic shellfish poisoning in new zealand.previously, we found brevetoxins pbtx-3, btx-b5 and btx-b1 in cockle, austrovenus (a.) stutchburyi, pbtx-2, pbtx-3 and btx-b1 in pacific oyster, crassostrea (c.) gigas and pbtx-3 and btx-b1 in greenshell mussel, perna (p.) canaliculus following outbreak of neurotoxic shellfish poisoning (nsp) in new zealand by isolation and/or liquid chromatography coupled with tandem mass spectrometry (lc-ms/ms). in this study, procedures for quantitative determination of pbtx-2 and btx-b5 were developed and th ...200415284012
discovery of genes expressed in response to perkinsus marinus challenge in eastern (crassostrea virginica) and pacific (c. gigas) oysters.the protozoan pathogen perkinsus marinus is the causative agent of dermo, a lethal disease of the eastern oyster crassostrea virginica, but not the pacific oyster crassostrea gigas. to understand the response of these two oysters to parasite exposure, a suppression subtractive hybridization (ssh) method was employed to characterize genes up-regulated during parasite challenge in both hemocytes and gills. the number of differentially expressed gene sequences obtained was 107 for c. virginica and ...200415302413
estimates of trace metal bioavailability to humans ingesting contaminated oysters.oysters, as very popular food items in france, are subject to rules concerning the maximum acceptable contents of trace metals in foods. the food standards for the quantities of metals permitted are always based on total metal concentrations, and not on the metal concentrations that are potentially bioavailable to the consumer (man). in order to estimate the percentages of accumulated trace metals (i.e. ag, cd, cu and zn) that are potentially bioavailable during consumption, we have used a simpl ...200415350688
early developmental stages of a protozoan parasite, marteilioides chungmuensis (paramyxea), the causative agent of the ovary enlargement disease in the pacific oyster, crassostrea gigas.a paramyxea, marteilioides chungmuensis, causes the irregular enlargement of the ovary in the pacific oyster, crassostrea gigas in korea and japan. the knowledge about the life cycle of the parasite has been limited to the sporulation stages within the oocyte of oysters. in this study, we used the parasite-specific dna probes and electron microscopy to experimentally infected oysters in a field and successfully clarified early developmental stages of the parasite. the parasite invaded the oyster ...200415380684
evaluation of biomarkers in oyster larvae in natural and polluted conditions.crassostrea gigas d-shaped larvae were subjected to different conditions of temperature and salinity for 24 h and four biomarkers (acetylcholinesterase (ache) activity, thiobarbituric acid reactive substances (tbars) levels, glutathione s-transferase (gst) and catalase (cat) activities) were measured. ache activity decreased when salinity increased from 25 to 30 and 35 psu at 20 and 25 degrees c. temperature did not seem to have an influence on ache activity. tbars levels increased as a function ...200415450859
novel member of the par domain bzip gene family isolated from pacific oyster, crassostrea gigas.a cdna encoding the first mollusk member of the par subfamily of bzip transcription factors has been characterized in the pacific oyster, crassostrea gigas. the sequence of the cdna predicts a protein of 260 amino acids that has 41-50% identity with the par domain, 72-79% identity with the basic dna-binding domain and 34-56% identity with the leucine zipper domain of other members of the par subfamily. polymerase chain reaction with reverse transcription indicates that this gene is expressed dur ...200415497439
genetic relationship between cultured populations of pacific oyster revealed by rapd analysis.we developed random amplified polymorphic dna (rapd) analysis for the assessment of the genetic relationship between cultured populations of the pacific oyster crassostrea gigas thunberg in hiroshima and goseong, the largest oyster farming areas in japan and korea, respectively. of 25 arbitrary primers comprising decamer nucleotides of random sequences, polymerase chain reaction amplifications with 5 different primers gave reproducible electrophoretic patterns. a total of 49 rapd markers were cl ...200415523154
vibrio crassostreae sp. nov., isolated from the haemolymph of oysters (crassostrea gigas).polyphasic analysis of five new vibrio isolates originating from the haemolymph of diseased cultured oysters is described. the new isolates were closely related to vibrio splendidus, having 98 % 16s rrna gene sequence similarity. gyrb phylogenetic analysis, fluorescent amplified-fragment length polymorphism (faflp) fingerprinting and dna-dna hybridization experiments clearly showed that the new isolates form a tight genomic group that is different from the currently known vibrio species. it is p ...200415545447
structural and functional evidences for a type 1 tgf-beta sensu stricto receptor in the lophotrochozoan crassostrea gigas suggest conserved molecular mechanisms controlling mesodermal patterning across bilateria.the transforming growth factor beta (tgfbeta) superfamily includes bone morphogenetic proteins, activins and tgf-betasensu stricto (s.s.). these ligands have been shown to play a key role in numerous biological processes including early embryonic development and immune regulation. they transduce their signal through a hetromeric complex of type i and type ii receptors. such receptors have been identified in ecdysozoans but none have been found as yet in the other major protostomal clade, the lop ...200415817226
cardiac responses of pacific oyster crassostrea gigas to agents modulating cholinergic function.to examine the functional effects of cholinergic modulation compounds in oyster hearts and to explore their possible use in monitoring intoxication with acetylcholine-esterase (ache) inhibitors such as organophosphates, tests were performed with in situ oyster heart preparations. the endogenous cholinergic agonist acetylcholine (ach), ache-resistant synthetic agonist carbachol, and the reversible carbamate type of ache inhibitor physostigmine, all potently depressed spontaneous cardiac contracti ...200415683842
transforming growth factor-beta-related proteins: an ancestral and widespread superfamily of cytokines in metazoans.members of the transforming growth factor beta (tgf-beta) superfamily of cell signalling polypeptides have attracted much attention because of their ability, from nematodes to mammals, to control cellular functions that in turn, regulate embryo development and tissue homeostasis. on the basis of structure similarities, the tgf-beta members (ligands, receptors and smads) are subdivided into tgf-beta sensu stricto, bone morphogenetic proteins (bmp) and activins. although bmp is the best characteri ...200415062644
cg-rel, the first rel/nf-kappab homolog characterized in a mollusk, the pacific oyster crassostrea gigas.we report here the identification and functional characterization of cg-rel, a gene encoding the crassostrea gigas homolog of rel/nf-kappab transcription factors found in insects and mammals. sequence and phylogenetic analysis showed that cg-rel shares the structural organization of rel/nf-kappab transcription factors of class ii. it includes a rel homology domain as well as a c-terminal transactivation domain (td). overexpression of cg-rel in the drosophila s2 cell line activated the expression ...200415013754
the oyster vasa-like gene: a specific marker of the germline in crassostrea gigas.the vasa gene is a key determinant for germline formation in eukaryotes. this gene, highly conserved through evolution, encodes a rna helicase protein member of the dead-box family. to understand the germline formation in oyster, we report here the isolation and the characterization of a vasa orthologue in crassostrea gigas (oyvlg). oyvlg contained the eight consensus domains of the dead-box including those providing rna unwinding activity. the expression pattern of oyvlg was examined in adult o ...200414985097
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