Publications

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glucomannan's protective effect on the virulence of vibrio splendidus in pacific oyster.we examine the effect of glucomannan, extracted from candida utilis yeast, on immune parameters and resistance to vibrio splendidus of crassostreagigas. our results showed that glucomannan was a successful anti-adhesive molecule; it exhibited a stronger inhibitory effect on adhesion of vibrio splendidus in infected crassostreagigas. vibrio splendidus viable cells number declined after incubation with glucomannan. furthermore, the glucomannan diet showed higher activity to trigger the immune resp ...201627492122
cloning and differential expression of a novel toll-like receptor gene in noble scallop chlamys nobilis with different total carotenoid content.to investigate whether toll like receptors (tlrs) genes do have an immune influence on noble scallop chlamys nobilis under pathogen stress, acute challenges lasting 48 h to vibrio parahaemolyticus, lipopolysaccharide (lps), polyinosinic polycytidylic acid (poly i:c), and pbs were conducted in two scallop stains of orange and brown with different carotenoids content. a novel toll-like receptor gene called cntlr-1 was cloned and its transcripts under different challenges were determined. meantime, ...201627403592
prevalence and antimicrobial susceptibility of vibrio parahaemolyticus isolated from oysters in korea.vibrio parahaemolyticus is the most prevalent gastroenteritis-causing pathogen in korea and in some other asian countries. it is frequently found in oysters and other seafood. this study monitored changes in the prevalence of v. parahaemolyticus and environmental parameters in oyster aquaculture environments in korea. from june to october 2014, we tested oysters (crassostrea gigas) from shellfish-harvesting areas off the west coast of korea. these 71 isolates were the sum of 16 (22.5%), 19 (26.8 ...201626511256
vibrio sonorensis sp. nov. isolated from a cultured oyster crassostrea gigas.strain caim 1076(t) was isolated from a cultured oyster crassostrea gigas in puerto peñasco, sonora state, méxico. the strain was taxonomically characterised by means of a genomic approach, comprising 16s rrna gene sequence analysis, multilocus sequence analysis (mlsa), the dna g+c content and whole genome analyses (ani and ggdc), and by phenotypic characterisation. strain caim 1076(t) was found to be catalase and oxidase positive, and cells were observed to be motile and facultative anaerobic. ...201627465217
a cytokine-like factor astakine accelerates the hemocyte production in pacific oyster crassostrea gigas.astakine has been reported to be a hematopoietic growth factor of prokineticin homolog firstly found in arthropods freshwater crayfish pacifastacus leniusculus. in the present study, an astakine homologous gene was identified from pacific oyster crassostrea gigas (designated cgastakine). the full length cdna of cgastakine encoded a polypeptide of 103 amino acids containing a prokineticin (pk) domain homologous to that in astakine from freshwater crayfish p. leniusculus. the deduced amino acid se ...201626523496
effect of 4-nonylphenol on the immune response of the pacific oyster crassostrea gigas following bacterial infection with vibrio campbellii.the xenoestrogen 4-nonylphenol (np) is a ubiquitous aquatic pollutant and has been shown to impair reproduction, development, growth and, more recently, immune function in marine invertebrates. we investigated the effects of short-term (7 d) exposure to low (2 μg l(-1)) and high (100 μg l(-1)) levels of np on cellular and humoral elements of the innate immune response of crassostrea gigas to a bacterial challenge. to this end, we measured 1) total hemocyte counts (thc), 2) relative transcript ab ...201627693202
liquid chromatography with mass spectrometry--detection of lipophilic shellfish toxins.a rapid multiple toxin method based on liquid chromatography with mass spectrometry (lc/ms) was developed for the detection of okadaic acid (oa), dinophysistoxin-1 (dtx-1), dtx-2, yessotoxin (ytx), homoytx, 45-hydroxy-ytx, 45-hydroxyhomo-ytx, pectenotoxin-1 (ptx-1), ptx-2, azaspiracid-1 (aza-1), aza-2, and aza-3. toxins were extracted from shellfish using methanol-water (80%, v/v) and were analyzed using a c8 reversed-phase column with a 5 mm ammonium acetate-acetonitrile mobile phase under grad ...201616385985
exceptionally large mitochondrial fragments to the nucleus in sequenced mollusk genomes.the available genome sequences of three mollusks (biomphalaria glabrata, aplysia californica and crassostrea gigas) were first used to investigate the nuclear mitochondrial dnas (numts) in mollusks. the analysis showed that the numt contents were high in b. glabrata (17.738 kb) and c. gigas (17.192 kb), of which all or almost all mtdna sequences were transferred to the nucleus, whereas numts are rare (584 bp) in a. californica. the length of numts was 61 to 5492 bp for b. glabrata, 1711 to 15,48 ...201625103445
distribution and evolution of the serine/aspartate racemase family in invertebrates.free d-amino acids have been found in various invertebrate phyla, while amino acid racemase genes have been identified in few species. the purpose of this study is to elucidate the distribution, function, and evolution of amino acid racemases in invertebrate animals. we searched the genbank databases, and found 11 homologous serine racemase genes from eight species in eight different invertebrate phyla. the cloned genes were identified based on their maximum activity as acropora millepora (cnida ...201626352274
wnt7b gene expression and functional analysis in the mussel mytilus coruscus.to understand the potential functions of wnt7b in different developmental stages and adult tissues of the mussel mytilus coruscus, the wnt7b gene was cloned using the rapid amplification of cdna ends technique. the full-length wnt7b gene was 1910 bp long, with a 1059-bp open reading frame encoding 352 amino acids. the amino acid sequence of the m. coruscus wnt7b gene shared high homology with that of homo sapiens (59%), mus musculus (61%), danio rerio (61% similarity), biomphalaria glabrata (62% ...201627819717
prevalence, characteristics and ecology of vibrio vulnificus found in new zealand shellfish.in new zealand, there have been no known cases of foodborne diseases linked to vibrio vulnificus and shellfish consumption, but two cases of wound infection have been reported. we evaluated the distribution, the effect of environmental parameters, the pheno-genotypic profile and the growth characteristics of strains isolated from shellfish.201626788798
exposure to the paralytic shellfish toxin producer alexandrium catenella increases the susceptibility of the oyster crassostrea gigas to pathogenic vibrios.the multifactorial etiology of massive crassostrea gigas summer mortalities results from complex interactions between oysters, opportunistic pathogens and environmental factors. in a field survey conducted in 2014 in the mediterranean thau lagoon (france), we evidenced that the development of the toxic dinoflagellate alexandrium catenella, which produces paralytic shellfish toxins (psts), was concomitant with the accumulation of psts in oyster flesh and the occurrence of c. gigas mortalities. in ...201626784228
distinct immune responses of juvenile and adult oysters (crassostrea gigas) to viral and bacterial infections.since 2008, massive mortality events of pacific oysters (crassostrea gigas) have been reported worldwide and these disease events are often associated with ostreid herpesvirus type 1 (oshv-1). epidemiological field studies have also reported oyster age and other pathogens of the vibrio genus are contributing factors to this syndrome. we undertook a controlled laboratory experiment to simultaneously investigate survival and immunological response of juvenile and adult c. gigas at different time-p ...201627439510
copper homeostasis at the host vibrio interface: lessons from intracellular vibrio transcriptomics.recent studies revealed that several vibrio species have evolved the capacity to survive inside host cells. however, it is still often ignored if intracellular stages are required for pathogenicity. virulence of vibrio tasmaniensis lgp32, a strain pathogenic for crassostrea gigas oysters, depends on entry into hemocytes, the oyster immune cells. we investigated here the mechanisms of lgp32 intracellular survival and their consequences on the host-pathogen interaction. entry and survival inside h ...201626472275
an invertebrate-specific mirna targeted the ancient cholinergic neuroendocrine system of oyster.acetylcholine (ach) is the main neurotransmitter in the cholinergic neuroendocrine system and plays an indispensable role in modulating diverse immune responses. as important transporters in choline uptake, choline transporter-like proteins (ctls) can control ach synthesis and release indirectly in multiple organisms. in this study, cgi-mir-2d, an invertebrate-specific mirna in oyster crassostrea gigas, is proved to repress the synthesis/release of ach by targeting cgctl1 and choline uptake in h ...201627488375
an invertebrate-specific and immune-responsive microrna augments oyster haemocyte phagocytosis by targeting cgiκb2.nuclear factor (nf)-κb pathway is an evolutionally conserved pathway in activating immune response, in which iκbs can repress the activation. in the present study, cgi-mir-2d, an invertebrate-specific microrna, was proved to regulate cgiκb2 expression and haemocyte phagocytosis during bacterial infection in oyster crassostrea gigas. the expression of cgi-mir-2d was significantly up-regulated after vibrio splendidus challenge, while cgiκb2 transcripts decreased. significant decreases in both lumi ...201627404434
cgi-mir-92d indirectly regulates tnf expression by targeting cds region of lipopolysaccharide-induced tnf-α factor 3 (cglitaf3) in oyster crassostrea gigas.tumor necrosis factor alpha (tnf-α) mediated inflammatory response plays indispensable roles in organisms defending against the invaded bacteria, during which micrornas have been found crucial by controlling multiple tnf-α-related genes. in the present study, cgi-mir-92d was annotated as a member of mir-17-92 family and could target the cds region of lipopolysaccharide (lps)-induced tnf-α factor (cglitaf3) in oyster crassostrea gigas. it was observed that cgi-mir-92d could be vigorously modulate ...201627346152
a novel siglec (cgsiglec-1) from the pacific oyster (crassostrea gigas) with broad recognition spectrum and inhibitory activity to apoptosis, phagocytosis and cytokine release.sialic acid binding immunoglobulin-type lectin (siglec) belongs to the immunoglobulin superfamily (igsf), which acts as regulator involved in glycan recognition and signal transduction in the immune and nervous systems. in the present study, a siglec gene (designated cgsiglec-1) was characterized from the pacific oyster, crassostrea gigas. the cdna of cgsiglec-1 was of 1251 bp encoding a predicted polypeptide of 416 amino acids. cgsiglec-1 was composed of two i-set immunoglobulin (ig) domains, o ...201627032602
flat oyster follows the apoptosis pathway to defend against the protozoan parasite bonamia ostreae.the in vitro model ostrea edulis hemocyte - bonamia ostreae is interesting to investigate host-parasite interactions at the cellular level. indeed, this unicellular parasite infects the flat oyster ostrea edulis and multiplies within hemocytes, the central effectors of oyster defenses. apoptosis is a mechanism used by many organisms to eliminate infected cells. in order to study the potential involvement of this mechanism in the oyster response to b. ostreae, in vitro experiments were carried ou ...201627431587
the cholinergic immune regulation mediated by a novel muscarinic acetylcholine receptor through tnf pathway in oyster crassostrea gigas.muscarinic receptors, which selectively take muscarine as their ligand, are critical for the immunological and physiological processes in animals. in the present study, the open region frame (orf) of a homologue of muscarinic acetylcholine (ach) receptor (machr) was amplified from oyster crassostrea gigas (named as cgmachr-1), whose full length was 1983 bp and the protein it encoded contained 660 amino acids with a seven transmembrane region. phylogeny analysis suggested that cgmachr-1 shared ho ...201627394930
bioaccumulation and persistence of faecal bacterial and viral indicators in mytilus edulis and crassostrea gigas.this study investigated the response of two shellfish species - mussels (mytilus edulis) and oysters (crassostrea gigas) to microbial contamination in order to gain a better understanding of the bioaccumulation and persistence of microorganisms under controlled conditions. m. edulis and c. gigas were placed in sterile laboratory-prepared artificial seawater and initial tests were carried out to ensure both faecal indicator bacteria (fib) and bacteriophages were below detection limits. fib and ph ...201627364864
comparative study of two single crd c-type lectins, cgclec-4 and cgclec-5, from pacific oyster crassostrea gigas.c-type lectins (ctls), a superfamily of ca(2+)-dependent carbohydrate-recognition proteins, are involved in nonself-recognition and pathogen elimination, and play crucial roles in the innate immunity. in the present study, two single crd c-type lectins, cgclec-4 and cgclec-5, were identified from oyster crassostrea gigas. the open reading frame (orf) of cgclec-4 and cgclec-5 encoded polypeptides of 152 and 150 amino acids, respectively. both cgclec-4 and cgclec-5 contained one crd with six conse ...201627765697
the modulation of extracellular superoxide dismutase in the specifically enhanced cellular immune response against secondary challenge of vibrio splendidus in pacific oyster (crassostrea gigas).extracellular superoxide dismutase (ecsod) is a copper-containing glycoprotein playing an important role in antioxidant defense of living cells exposed to oxidative stress, and also participating in microorganism internalization and cell adhesion in invertebrates. ecsod from oyster (designated cgecsod) had been previously reported to bind lipopolysaccharides (lps) and act as a bridge molecule in vibrio splendidus internalization. its mrna expression pattern, pamp binding spectrum and microorgani ...201627268574
the modulation of haemolymph arginine kinase on the extracellular atp induced bactericidal immune responses in the pacific oyster crassostrea gigas.arginine kinase is an important phosphagen kinase (pk) which plays an essential role in atp buffering systems in invertebrates. in the present study, an arginine kinase (designated cgak) was isolated by the lipopolysaccharide (lps) affinity chromatography from the haemolymph of crassostrea gigas. cgak could directly bind to lps in a concentration-dependent manner with the dissociation constant (kd) of 2.46 × 10(-6) m. the interaction with lps significantly decreased the atp hydrolytic activity o ...201627033465
a novel junctional adhesion molecule a (cgjam-a-l) from oyster (crassostrea gigas) functions as pattern recognition receptor and opsonin.junctional adhesion molecule (jam), a subfamily of immunoglobulin superfamily (igsf) with a couple of immunoglobulin domains, can act as regulator in homeostasis and inflammation of vertebrates. in the present study, a structural homolog of jam-a (designated cgjam-a-l) was screened out from oyster, crassostrea gigas, through a search of jam-a d1 domain (n-terminal ig domain in jam-a). the cdna of cgjam-a-l was of 1188 bp encoding a predicted polypeptide of 395 amino acids. the immunoreactive are ...201626434620
in situ hybridization and histopathological observations during ostreid herpesvirus-1-associated mortalities in pacific oysters crassostrea gigas.in a previous longitudinal study conducted during a mortality investigation associated with ostreid herpesvirus-1 (oshv-1) microvariant in new zealand pacific oysters in 2010-2011, temporality of oshv-1 nucleic acid detection by real-time pcr assay and onset of pacific oyster mortality was observed. the present study further elucidated the role of oshv-1 using an in situ hybridization (ish) assay on sections of pacific oysters collected from the same longitudinal study. hybridization of the labe ...201627901503
occurrence of oshv-1 in crassostrea gigas cultured in ireland during an exceptionally warm summer. selection of less susceptible oysters.the occurrence of oshv-1, a herpes virus causing mass mortality in the pacific oyster crassostrea gigas was investigated with the aim to select individuals with different susceptibility to the infection. naïve spat transferred to infected areas and juveniles currently being grown at those sites were analyzed using molecular and histology approaches. the survey period distinguishes itself by very warm temperatures reaching up to 3.5°c above the average. the virus was not detected in the virus fre ...201627877131
ostreid herpesvirus in wild oysters from the huelva coast (sw spain).this is the first report of ostreid herpesvirus 1 microvariant (oshv-1 µvar) infecting natural oyster beds located in huelva (sw spain). the virus was detected in 3 oyster species present in the intertidal zone: crassostrea gigas (thunberg, 1793), c. angulata (lamarck, 1819) and, for the first time, in ostrea stentina payraudeau, 1826. oysters were identified by a specific polymerase chain reaction (pcr) and posterior restriction fragment length polymorphism (rflp) analysis based on cytochrome o ...201627503919
single or dual experimental infections with vibrio aestuarianus and oshv-1 in diploid and triploid crassostrea gigas at the spat, juvenile and adult stages.french production of the pacific cupped oyster, crassostrea gigas, is currently threatened by two pathogens, oshv-1 and v. aestuarianus. while oysters selected for their higher resistance to oshv-1 are now available for the industry, the impact of v. aestuarianus on such oysters is unknown, especially for triploids. in addition, experimental infection has used the virus or the bacteria alone, but there have been no investigations of dual exposure to these pathogens. this study is the first repor ...201627503207
tank-binding kinase-1 broadly affects oyster immune response to bacteria and viruses.as a benthic filter feeder of estuaries, the immune system of oysters provides one of the best models for studying the genetic and molecular basis of the innate immune pathway in marine invertebrates and examining the influence of environmental factors on the immune system. here, the molecular function of molluscan tank-binding kinase-1 (tbk1) (which we named cgtbk1) was studied in the pacific oyster, crassostrea gigas. compared with known tbk1 proteins in other model organisms, cgtbk1 contains ...201627422757
ostreid herpesvirus type 1 genomic diversity in wild populations of pacific oyster crassostrea gigas from italian coasts.ostreid herpesvirus 1 (oshv-1) is a significant pathogen affecting the young pacific oyster crassostrea gigas, worldwide. a new variant, oshv-1 μvar, has been associated with recurrent mortality events in europe since 2008. epidemiological data collection is key for global risk assessment; however little is known about health status and genotypes present in european wild oyster beds. most studies to date have involved only cultivated individuals during mortality events, and reported low genotype ...201627234424
in situ localization and tissue distribution of ostreid herpesvirus 1 proteins in infected pacific oyster, crassostrea gigas.immunohistochemistry (ihc) assays were conducted on paraffin sections from experimentally infected spat and unchallenged spat produced in hatchery to determine the tissue distribution of three viral proteins within the pacific oyster, crassostrea gigas. polyclonal antibodies were produced from recombinant proteins corresponding to two putative membrane proteins and one putative apoptosis inhibitor encoded by orf 25, 72, and 87, respectively. results were then compared to those obtained by in sit ...201627066775
experimental infection of european flat oyster ostrea edulis with ostreid herpesvirus 1 microvar (oshv-1μvar): mortality, viral load and detection of viral transcripts by in situ hybridization.ostreid herpesvirus 1 (oshv-1) infections have been reported in several bivalve species. mortality of pacific oyster crassostrea gigas spat has increased considerably in europe since 2008 linked to the spread of a variant of oshv-1 called μvar. in the present study we demonstrated that o. edulis juveniles can be infected by oshv-1μvar when administered as an intramuscular injection. mortality in the oysters injected with oshv-1μvar was first detected 4 days after injection and reached 25% mortal ...201626945849
infectious diseases in oyster aquaculture require a new integrated approach.emerging diseases pose a recurrent threat to bivalve aquaculture. recently, massive mortality events in the pacific oyster crassostrea gigas associated with the detection of a microvariant of the ostreid herpesvirus 1 (oshv-1µvar) have been reported in europe, australia and new zealand. although the spread of disease is often viewed as a governance failure, we suggest that the development of protective measures for bivalve farming is presently held back by the lack of key scientific knowledge. i ...201626880845
summer mortalities and detection of ostreid herpesvirus microvariant in pacific oyster crassostrea gigas in sweden and norway.the pacific oyster crassostrea gigas has recently expanded its range in scandinavia. the expansion is presumably a result of northwards larval drift. massive settlements were recorded in many areas along the swedish west coast and southern norway in 2013 and 2014. after the spawning season in 2014, the temperature of the surface water peaked at 24-26°c. after this period, high and sudden mortalities occurred in a swedish hatchery and in wild populations along the swedish west coast and south coa ...201626758650
characterization of oyster voltage-dependent anion channel 2 (vdac2) suggests its involvement in apoptosis and host defense.genomic and transcriptomic studies have revealed a sophisticated and powerful apoptosis regulation network in oyster, highlighting its adaptation to sessile life in a highly stressful intertidal environment. however, the functional molecular basis of apoptosis remains largely unexplored in oysters. in this study, we focused on a representative apoptotic gene encoding voltage-dependent anion channel 2 (vdac2), a porin that abounds at the mitochondrial outer membrane. this is the first report on t ...201626727366
detection and distribution of ostreid herpesvirus 1 in experimentally infected pacific oyster spat.high mortality rates are reported in spat and larvae of pacific oyster crassostrea gigas and associated with ostreid herpesvirus 1 (oshv-1) detection in france. although the viral infection has been experimentally reproduced in oyster larvae and spat, little knowledge is currently available concerning the viral entry and its distribution in organs and tissues. this study compares oshv-1 dna and rna detection and localization in experimentally infected oysters using two virus doses: a low dose th ...201626674009
ostreid herpesvirus oshv-1 μvar in pacific oysters crassostrea gigas (thunberg 1793) of the wadden sea, a unesco world heritage site.the wadden sea is an extensive wetland area, recognized as unesco world heritage site of international importance. since the mid-1990s, the invasive pacific oyster crassostrea gigas (thunberg 1793) population in the area has grown exponentially, having a distinct impact on the ecosystem. the recent spread of the emerging oyster pathogen ostreid herpesvirus oshv-1 μvar worldwide and specifically in the oyster culture areas in the south of the netherlands raised the question whether the virus may ...201625643634
a new non-phagocytic tlr6 with broad recognition ligands from pacific oyster crassostrea gigas.toll like receptors (tlrs) are evolutionarily prevalent recognition molecules in the animalia and plantae kingdom, which play vital roles in immune defense and homeostasis maintenance. recently, the expansion of tlrs has been reported in invertebrate genomes, but the characters and immune functions of these expanded tlrs were still not well known. in the present study, a new member of tlr family with five lrr domains was identified in crassostrea gigas (designated cgtlr6). it shared homology wit ...201627443817
molecular characterization and functional analysis of tumor necrosis factor receptor-associated factor 2 in the pacific oyster.tumor necrosis factor receptor (tnfr)-associated factors (trafs) are a family of crucial adaptors, playing vital roles in mediating signal transduction in immune signaling pathways, including rig-i-like receptor (rlr) signaling pathway. in the present study, a new traf family member (cgtraf2) was identified in the pacific oyster, crassostrea gigas. comparison and phylogenetic analysis revealed that cgtraf2 could be a new member of the invertebrate traf2 family. quantitative real-time pcr reveale ...201626621757
functional characterisation of phagocytes in the pacific oyster crassostrea gigas.invertebrates lack canonical adaptive immunity and mainly rely on innate immune system to fight against pathogens. the phagocytes, which could engulf and kill microbial pathogens, are likely to be of great importance and have to undertake significant roles in invertebrate immune defense. in the present study, flow cytometry combined with histological and lectin staining was employed to characterise functional features of phagocytes in the pacific oyster crassostrea gigas. based on the cell size ...201627994957
adipokinetic hormones and their g protein-coupled receptors emerged in lophotrochozoa.most multicellular animals belong to two evolutionary lineages, the proto- and deuterostomia, which diverged 640-760 million years (myr) ago. neuropeptide signaling is abundant in animals belonging to both lineages, but it is often unclear whether there exist evolutionary relationships between the neuropeptide systems used by proto- or deuterostomes. an exception, however, are members of the gonadotropin-releasing hormone (gnrh) receptor superfamily, which occur in both evolutionary lineages, wh ...201627628442
molecular cloning and characterization of full-length cdna of calmodulin gene from pacific oyster crassostrea gigas.the shell of the pearl oyster (pinctada fucata) mainly comprises aragonite whereas that of the pacific oyster (crassostrea gigas) is mainly calcite, thereby suggesting the different mechanisms of shell formation between above two mollusks. calmodulin (cam) is an important gene for regulating the uptake, transport, and secretion of calcium during the process of shell formation in pearl oyster. it is interesting to characterize the cam in oysters, which could facilitate the understanding of the di ...201627703977
the mirna biogenesis in marine bivalves.small non-coding rnas include powerful regulators of gene expression, transposon mobility and virus activity. among the various categories, mature micrornas (mirnas) guide the translational repression and decay of several targeted mrnas. the biogenesis of mirnas depends on few gene products, essentially conserved from basal to higher metazoans, whose protein domains allow specific interactions with dsrna. here, we report the identification of key genes responsible of the mirna biogenesis in 32 b ...201626989613
apoptosis by rgd-containing peptides observed in hemocytes of the pacific oyster, crassostrea gigas.we observed in vitro that after treatment with the arg-gly-asp (rgd) peptide, non-spreading crassostrea gigas hemocytes underwent cell death. utilizing a combination of a hoechst staining method and a dna fragmentation assay, the typical features of apoptosis were shown, i.e. cell shrinkage, membrane blebbing, chromatin condensation, and dna fragmentation. the hemocyte cell death caused by the rgd peptide appears to be sequence-specific, since no induction was shown in the alanine-substituted co ...201612697309
encapsulation of a lipid precursor, the eicosapentaenoic acid, to study the development of the crassostrea gigas oyster flavours.the present study is part of a larger project whose aim is to understand how the oyster crassostrea gigas develops its aromas from a lipid precursor, the eicosapentaenoic acid (epa), in glyceride form. the objective of this study is, therefore, to prepare an encapsulation process that will enable the bivalve to be supplied with this lipid precursor. the complex coacervation method was chosen as it gave the best compatible microcapsules with respect to the nutritional aspects of oyster (i.e. dige ...201612519700
multiresidue method for determination of algal toxins in shellfish: single-laboratory validation and interlaboratory study.a method that uses liquid chromatography with tandem mass spectrometry (lc/ms/ms) has been developed for the highly sensitive and specific determination of amnesic shellfish poisoning toxins, diarrhetic shellfish poisoning toxins, and other lipophilic algal toxins and metabolites in shellfish. the method was subjected to a full single-laboratory validation and a limited interlaboratory study. tissue homogenates are blended with methanol-water (9 + 1), and the centrifuged extract is cleaned up wi ...201616001850
sub-chronic exposure to fluoxetine in juvenile oysters (crassostrea gigas): uptake and biological effects.the bioconcentration potential of fluoxetine (flx) and its biological effects were investigated in juvenile pacific oyster exposed for 28 days to environmentally relevant concentrations of flx (1 ng l(-1), 100 ng l(-1) and up to 10 μg l(-1)). flx bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. nevertheless, flx did not induce oyster mortality, delayed gametogenesis, or lead to adverse his ...201625315935
assessment of sediment toxicity in the lagoon of venice (italy) using a multi-species set of bioassays.within the framework of a weight of evidence (woe) approach, a set of four toxicity bioassays involving the amphipod corophium volutator (10 d lethality test on whole sediment), the sea urchin paracentrotus lividus (fertilization and embryo toxicity tests on elutriate) and the pacific oyster crassostrea gigas (embryo toxicity test on elutriate) was applied to sediments from 10 sampling sites of the venice lagoon (italy). sediments were collected during three campaigns carried out in may 2004 (sp ...201626409652
differential expression of novel metabolic and immunological biomarkers in oysters challenged with a virulent strain of oshv-1.early lifestages of the pacific oyster (crassostrea gigas) are highly susceptible to infection by oshv-1 μvar, but little information exists regarding metabolic or pathophysiological responses of larval hosts. using a metabolomics approach, we identified a range of metabolic and immunological responses in oyster larvae exposed to oshv-1 μvar; some of which have not previously been reported in molluscs. multivariate analyses of entire metabolite profiles were able to separate infected from non-in ...201728373065
detection of ostreid herpesvirus 1 microvariant dna in aquatic invertebrate species, sediment and other samples collected from the georges river estuary, new south wales, australia.ostreid herpesvirus 1 microvariants (oshv-1) present a serious threat to the australian crassostrea gigas industry. of great concern is the propensity for mortality due to the virus recurring each season in farmed oysters. however, the source of the virus in recurrent outbreaks remains unclear. reference strain ostreid herpesvirus 1 (oshv-1 ref) and other related variants have been detected in several aquatic invertebrate species other than c. gigas in europe, asia and the usa. the aim of this s ...201728117303
two short peptidoglycan recognition proteins from crassostrea gigas with similar structure exhibited different pamp binding activity.peptidoglycan recognition protein (pgrp) is an essential molecule in innate immunity for both invertebrates and vertebrates, owing to its prominent ability in specifically recognizing bacterial peptidoglycan (pgn) and eliminating the invading bacteria. in the present study, the full length cdna of two pgrp genes, cgpgrps2 and cgpgrps4, were cloned from oyster crassostrea gigas. their amino acid sequences both contained one signal peptide, one typical pgrp/amidase domain with conserved catalytic ...201728042081
the hematopoiesis in gill and its role in the immune response of pacific oyster crassostrea gigas against secondary challenge with vibrio splendidus.increasing evidences have demonstrated that the invertebrate gill is a predominant tissue participating in the immune response during pathogen challenge. in the present study, the hematopoiesis and immune activities in gill of pacific oyster crassostrea gigas were investigated. stem-like cells with big nuclei and thin cytoplasm were found in the tubules of gill filaments, where dna synthesis is active and hemocytes production are exuberant. the oysters primarily stimulated by formaldehyde-killed ...201728159592
the b-cell translocation gene 1 (cgbtg1) identified in oyster crassostrea gigas exhibit multiple functions in immune response.b-cell translocation gene 1 (btg1) is a member of the anti-proliferative gene family, which plays important roles in regulation of cell cycle. in the present study, a b-cell translocation gene 1 molecule homologue (designed cgbtg1) are identified and characterized in oyster crassostrea gigas. cgbtg1 contains a conserved btg domain with box a and box b motifs, and it shares high similarities with both btg1 and btg2 proteins in vertebrates. cgbtg1 mrna is predominantly expressed in hemocytes, and ...201727940367
viruses infecting marine molluscs.although a wide range of viruses have been reported in marine molluscs, most of these reports rely on ultrastructural examination and few of these viruses have been fully characterized. the lack of marine mollusc cell lines restricts virus isolation capacities and subsequent characterization works. our current knowledge is mostly restricted to viruses affecting farmed species such as oysters crassostrea gigas, abalone haliotis diversicolor supertexta or the scallop chlamys farreri. molecular app ...201728189502
genetic parameters of resistance to vibrio aestuarianus, and oshv-1 infections in the pacific oyster, crassostrea gigas, at three different life stages.in france, two main diseases threaten pacific oyster production. since 2008, crassostrea gigas spat have suffered massive losses due to the ostreid herpesvirus oshv-1, and since 2012, significant mortalities in commercial-size adults have been related to infection by the bacterium vibrio aestuarianus. the genetic basis for resistance to v. aestuarianus and oshv-1 and the nature of the genetic correlation between these two traits were investigated by using 20 half-sib sire families, each containi ...201728201985
identification and expression characterization of three wnt signaling genes in pearl oyster (pinctada fucata).the wnt signaling pathway plays an important role in animal development and in the biomineralization process. at present, although the biomineralization mechanism in pearl oyster (pinctada fucata) has been extensively studied, there is little research on the wnt signaling pathway in pearl oyster. to understand the potential role of the wnt signaling pathway in pearl oyster, we cloned and sequenced three genes from the wnt signaling pathway in pearl oyster that encode the following proteins: β-ca ...201726969109
molecular characterization of pacific oyster (crassostrea gigas) irak4 gene and its role in myd88-dependent pathway.interleukin-1 receptor-associated kinases (iraks) play important roles in myd88-dependent tlr signaling, the crucial innate immune pathway in molluscs. in this study, we examined the full-length irak4 genetic sequence in the pacific oyster (crassostrea gigas) by molecular cloning. phylogenetic analysis revealed that cgirak4 is most closely related to mytilus edulis, and forms a clade with other molluscs. cgirak4 transcripts are widely expressed in all tissues, with the highest expression observe ...201728223161
c-jun n-terminal kinase (jnk) is involved in immune defense against bacterial infection in crassostrea hongkongensis.c-jun n-terminal kinase (jnk) is a universal and essential subgroup of the mitogen-activated protein kinase (mapk) superfamily, which is highly conserved from yeast to mammals and functions in a variety of physiological and pathological processes. in this study, we report the first oyster jnk gene homolog (chjnk) and its biological functions in the hong kong oyster crassostrea hongkongensis. the chjnk protein consists of 383 amino acids and contains a conserved serine/threonine protein kinase (s ...201727840294
a molluscan extracellular signal-regulated kinase is involved in host response to immune challenges in vivo and in vitro.extracellular signal-regulated kinases (erks) are a group of highly conserved serine/threonine-specific protein kinases that function as important signaling intermediates in mitogen-activated protein kinase (mapk) pathways, which are involved in a wide variety of cellular activities, including proliferation, inflammation and cytokine production. however, little is known about the roles of this kinase in mollusk immunity. in this study, we identified a molluscan erk homolog (cherk) in the hong ko ...201728159693
spatial and temporal distribution of mercury and methylmercury in bivalves from the french coastline.marine mercury (hg) concentrations have been monitored in the french coastline for the last half a century using bivalves. the analyses presented in this study concerned 192 samples of bivalves (mussels: mytilus edulis and mytilus galloprovincialis and oysters: crassostrea gigas and isognomon alatus) from 77 sampling stations along the french coast and in the french antilles sea. the goals of this study were to assess mehg levels in various common bivalves from french coastline, and to identify ...201727745976
insights from the shell proteome: biomineralization to adaptation.bivalves have evolved a range of complex shell forming mechanisms that are reflected by their incredible diversity in shell mineralogy and microstructures. a suite of proteins exported to the shell matrix space plays a significant role in controlling these features, in addition to underpinning some of the physical properties of the shell itself. although, there is a general consensus that a minimum basic protein tool kit is required for shell construction, to date, this remains undefined. in thi ...201727744410
preparation and antioxidant activities of oligosaccharides from crassostrea gigas.oligosaccharides were prepared from crassostrea gigas by hydrolysis of polysaccharide in c. gigas with peroxide oxygen (h2o2). the hydrolysates were cleared of protein, filtered, ultrafiltered and precipitated with absolute ethanol to give c. gigas oligosaccharides (cgos). factors affecting cgo yields, i.e., reaction time, temperature, and h2o2 concentration, were optimised as follows: 2.96h reaction time, 84.71°c reaction temperature, and 2.46% h2o2 concentration. under these conditions, the ma ...201727596415
assessment of housekeeping genes as internal references in quantitative expression analysis during early development of oyster.the early development of mollusks exhibits important characteristics from the developmental and evolutionary perspective. with the increasing number of genome-wide studies, accurate analyses of quantitative gene expression during development are impeded by the lack of validated reference genes. to improve the situation, in this study, we analyzed the expression stability of seven candidate housekeeping genes during early development of the pacific oyster crassostrea gigas: actin, glyceraldehyde- ...201727582049
the granulocytes are the main immunocompetent hemocytes in crassostrea gigas.hemocytes comprise diverse cell types with morphological and functional heterogeneity and play indispensable roles in immunological homeostasis of invertebrates. the morphological classification of different hemocytes in mollusk has been studied since the 1970's, yet the involvement of the different sub-populations in immune functions is far from clear. in the present study, three types of hemocytes were morphologically identified and separated as agranulocytes, semi-granulocytes and granulocyte ...201727693685
molecular characterization of an adipokinetic hormone-related neuropeptide (akh) from a mollusk.adipokinetic hormones (akh) are key regulators of energy mobilization in insects. with the growing number of genome sequence available, the existence of genes encoding akh related peptides has now been established in protostomes. here we investigated the occurrence of a mature akh-like neuropeptide (cg-akh) in the oyster crassostrea gigas. we unambiguously elucidated the primary structure of this neuropeptide by mass spectrometry from peptidic extracts of oyster visceral ganglia. cg-akh mature p ...201727823954
biochemical alterations in native and exotic oyster species in brazil in response to increasing temperature.the increase of temperature in marine coastal ecosystems due to atmospheric greenhouse gas emissions is becoming an increasing threat for biodiversity worldwide, and may affect organisms' biochemical performance, often resulting in biogeographical shifts of species distribution. at the same time, the introduction of non-native species into aquatic systems also threatens biodiversity and ecosystem functions. oysters are among the most valuable socio economic group of bivalve species in global fis ...201727816652
a comparative proteomic analysis reveals important proteins for the fertilization and early embryonic development of the oyster crassostrea gigas.molluscan development involves important features that are important to understanding not only molluscan ontogeny but also animal evolution. to gain insight into the gamete proteome and protein function in fertilization and early development, we analyzed the proteomes of unfertilized oocytes and early embryos (2/4-cell stage) of the pacific oyster, crassostrea gigas. an oocyte reference map containing 116 protein spots, of which 69 were identified, revealed a high abundance of vitellogenin-deriv ...201727880033
transcriptome analysis of the freshwater pearl mussel (cristaria plicata) mantle unravels genes involved in the formation of shell and pearl.cristaria plicata, a bivalve widespread in eastern asia fresh water, is utilized as the freshwater pearl mussel in china. with a high economic value in pearl production, it is also an ideal object used for the studies on biomineralization in freshwater. in the research, we performed a large-scale sequencing of cristaria plicata mantle transcriptome using illumina hiseq™ 2500, obtaining 98,501 unigenes with 67,817,724 bases. 22.28 and 16.64% of the unigenes were annotated in the nr and swiss-prot ...201727987057
expression patterns indicate that bmp2/4 and chordin, not bmp5-8 and gremlin, mediate dorsal-ventral patterning in the mollusk crassostrea gigas.though several bilaterian animals use a conserved bmp2/4-chordin antagonism to pattern the dorsal-ventral (dv) axis, the only lophotrochozoan species in which early dv patterning has been studied to date, the leech helobdella robusta, appears to employ bmp5-8 and gremlin. these findings call into question the conservation of a common dv patterning mechanism among bilaterian animals. to explore whether the unusual dv patterning mechanism in h. robusta is also used in other lophotrochozoan species ...201727987051
combined effects of temperature and copper and s-metolachlor on embryo-larval development of the pacific oyster, crassostrea gigas.this study evaluates the combined effects of two contaminants (copper and a herbicide s-metolachlor) and temperature on the early life stages of the pacific oyster crasssotrea gigas, which is native to arcachon bay (southwest france). the responses of d-larvae, obtained from wild and cultivated oysters, were investigated for one year during the oyster breeding period at different sampling sites and compared with the response of d-larvae from a commercial hatchery. embryotoxicity was measured by ...201727986302
parental diuron-exposure alters offspring transcriptome and fitness in pacific oyster crassostrea gigas.one of the primary challenges in ecotoxicology is to contribute to the assessment of the ecological status of ecosystems. in this study, we used pacific oyster crassostrea gigas to explore the effects of a parental exposure to diuron, a herbicide frequently detected in marine coastal environments. the present toxicogenomic study provides evidence that exposure of oyster genitors to diuron during gametogenesis results in changes in offspring, namely, transcriptomic profile alterations, increased ...201728388477
vasa expression suggests shared germ line dynamics in bivalve molluscs.germ line segregation can occur during embryogenesis or after embryogenesis completion, with multipotent cells able to give rise to both germ and somatic cells in the developing juvenile or even in adulthood. these undifferentiated cells, in some animals, are self-renewing stem cells. in all these cell lineages, the same set of genes, among which vasa, appears to be expressed. we traced vasa expression during the peculiar gonad rebuilding of bivalves to verify its presence from undifferentiated ...201728386635
identification of conserved proteins from diverse shell matrix proteome in crassostrea gigas: characterization of genetic bases regulating shell formation.the calcifying shell is an excellent model for studying biomineralization and evolution. however, the molecular mechanisms of shell formation are only beginning to be elucidated in mollusca. it is known that shell matrix proteins (smps) play important roles in shell formation. with increasing data of shell matrix proteomes from various species, we carried out a blastp bioinformatics analysis using the shell matrix proteome from crassostrea gigas against 443 smps from nine other species. the high ...201728374770
population-specific genotype x genotype x environment interactions in bacterial disease of early life stages of pacific oyster larvae.the consequences of emerging marine diseases on the evolutionary trajectories of affected host populations in the marine realm are largely unexplored. evolution in response to natural selection depends on the genetic variation of the traits under selection and the interaction of these traits with the environment (gxe). however, in the case of diseases, pathogen genotypes add another dimension to this interaction. therefore, the study of disease resistance needs to be extended to the interaction ...201728352294
phylogenetics of lophotrochozoan bhlh genes and the evolution of lineage-specific gene duplicates.the gain and loss of genes encoding transcription factors is of importance to understanding the evolution of gene regulatory complexity. the basic helix-loop-helix (bhlh) genes encode a large superfamily of transcription factors. we systematically classify the bhlh genes from five mollusc, two annelid and one brachiopod genomes, tracing the pattern of bhlh gene evolution across these poorly-studied phyla. 56 to 88 bhlh genes were identified in each genome, with most identifiable as members of pr ...201728338988
construction and evaluation of a high-density snp array for the pacific oyster (crassostrea gigas).single nucleotide polymorphisms (snps) are widely used in genetics and genomics research. the pacific oyster (crassostrea gigas) is an economically and ecologically important marine bivalve, and it possesses one of the highest levels of genomic dna variation among animal species. pacific oyster snps have been extensively investigated; however, the mechanisms by which these snps may be used in a high-throughput, transferable, and economical manner remain to be elucidated. here, we constructed an ...201728328985
a production calendar based on water temperature, spat size, and husbandry practices reduce oshv-1 μvar impact on cultured pacific oyster crassostrea gigas in the ebro delta (catalonia), mediterranean coast of spain.since 2006, the production of pacific oyster crassostrea gigas in the ebro delta area has dramatically declined from around 800 metric tons (mt) per year to 138 mt in 2011. this decline in production has had a significant socio-economic impact in a region where the shellfish sector is a traditional economic activity for many families. the identified agent responsible for this reduction in c. gigas production was ostreid herpesvirus microvar (oshv-1 μvar), which has been associated with c. gigas ...201728316573
invasion trajectory of pacific oysters in the northern wadden sea.invasion trajectories of introduced alien species usually begin with a long establishment phase of low abundance, often followed by exponential expansion and subsequent adjustment phases. we review the first 26 years of feral pacific oysters crassostrea gigas around the island of sylt in the wadden sea (north sea, ne atlantic), and reveal causal conditions for the invasion phases. sea-based oyster farming with repeated introductions made establishment of feral oysters almost inevitable. beds of ...201728316346
a norepinephrine-responsive mirna directly promotes cghsp90aa1 expression in oyster haemocytes during desiccation.oyster crassostrea gigas is one model mollusc inhabiting in the intertidal zone and is frequently stressed by desiccation. the adaptation mechanism of oyster to environmental stress involves multiple levels, and mirna is one of the most important regulators in post-transcriptional level. in the present study, an oyster norepinephrine-responsive mirna cgi-mir-365 was proved to contribute to the host adaptation against desiccation by directly promoting the expression of cghsp90aa1. briefly, a sign ...201728286314
transcriptomic analysis of oyster crassostrea gigas larvae illustrates the response patterns regulated by catecholaminergic system upon acute heat and bacterial stress.bacterial infection and heat stress, as two major environmental threats of marine molluscs, could affect larval development and dramatically promote mortality of oysters. in the present study, next-generation sequencing, together with determinations of mrna expression and measurements of enzyme activities, were employed to understand the response patterns of oyster larvae under acute heat and bacterial stress. after rna-seq, a total of 9472 differentially expressed genes including 4895 significa ...201728283443
a soxc gene related to larval shell development and co-expression analysis of different shell formation genes in early larvae of oyster.among the potential larval shell formation genes in mollusks, most are expressed in cells surrounding the shell field during the early phase of shell formation. the only exception (cgi-tyr1) is expressed in the whole larval mantle and thus represents a novel type of expression pattern. this study reports another gene with such an expression pattern. the gene encoded a soxc homolog of the pacific oyster crassostrea gigas and was named cgi-soxc. whole-mount in situ hybridization revealed that the ...201728280925
first data on three bivalve species exposed to an intra-harbour polymetallic contamination (la rochelle, france).evaluating diffuse sediment contamination in the environment is a major concern with the aim of reaching a good chemical and ecological state of the littoral zone. in this study the risks of chronic chemical contamination and consequences in the bivalves crassostrea gigas, mytilus sp. and mimachlamys varia were evaluated in coastal environments. the objective here was to understand the anthropological phenomena that affect the functioning of the marina of la rochelle (semi-closed environment). h ...201728232231
upregulating nrf2-dependent antioxidant defenses in pacific oysters crassostrea gigas: investigating the nrf2/keap1 pathway in bivalves.analysis of the pacific oyster crassostrea gigas annotated genome revealed genes with conserved sequences belonging to typical cap 'n' collar nrf2 domain, a major player in antioxidant protection, and domains belonging to nrf2 cytoplasmic repressor (keap1), but little is known about nrf2/keap1 induction in bivalves. c. gigas were exposed to waterborne 10 and 30μm curcumin, a known inducer of the mammalian nrf2. curcumin disappeared from the seawater after 10h, and accumulated in the gills (10h) ...201728216009
a carbonic anhydrase serves as an important acid-base regulator in pacific oyster crassostrea gigas exposed to elevated co2: implication for physiological responses of mollusk to ocean acidification.carbonic anhydrases (cas) have been demonstrated to play an important role in acid-base regulation in vertebrates. however, the classification and modulatory function of cas in marine invertebrates, especially their responses to ocean acidification remain largely unknown. here, a cytosolic α-ca (designated as cgcaii-1) was characterized from pacific oyster crassostrea gigas and its molecular activities against co2 exposure were investigated. cgcaii-1 possessed a conserved ca catalytic domain, wi ...201728204970
sub-lethal effects of a glyphosate-based commercial formulation and adjuvants on juvenile oysters (crassostrea gigas) exposed for 35days.glyphosate-based herbicides include active matter and adjuvants (e.g. polyethoxylated tallow amines, poeas). in addition to a previous investigation on the effect of glyphosate on oysters, the aim of the present study was to investigate the effects of sub-chronic exposures (35days) to three concentrations (0.1, 1 and 100μgl(-1)) of roundup express® (rex) and poeas on oysters belonging to the same age group. low mortality rates were calculated, and only few significant differences (i.e. shell len ...201728202277
the modulation role of serotonin in pacific oyster crassostrea gigas in response to air exposure.serotonin, also known as 5-hydroxytryptamine (5-ht), is a critical neurotransmitter in the neuroendocrine-immune regulatory network and involved in regulation of the stress response in vertebrates and invertebrates. in the present study, serotonin was found to be widely distributed in the tissues of pacific oyster crassostrea gigas, including haemolymph, gonad, visceral ganglion, mantle, gill, labial palps and hepatopancreas, and its concentration increased significantly in haemolymph and mantle ...201728159695
molecular characterization of voltage-gated sodium channels and their relations with paralytic shellfish toxin bioaccumulation in the pacific oyster crassostrea gigas.paralytic shellfish toxins (pst) bind to voltage-gated sodium channels (nav) and block conduction of action potential in excitable cells. this study aimed to (i) characterize nav sequences in crassostrea gigas and (ii) investigate a putative relation between nav and pst-bioaccumulation in oysters. the phylogenetic analysis highlighted two types of nav in c. gigas: a nav1 (cgnav1) and a nav2 (cgnav2) with sequence properties of sodium-selective and sodium/calcium-selective channels, respectively. ...201728106838
the neuroendocrine immunomodulatory axis-like pathway mediated by circulating haemocytes in pacific oyster crassostrea gigas.the neuroendocrine-immune (nei) regulatory network is a complex system, which plays an indispensable role in the immunity of host. in this study, a neuroendocrine immunomodulatory axis (nia)-like pathway mediated by the nervous system and haemocytes was characterized in the oyster crassostrea gigas once invaded pathogen was recognized by the host, the nervous system would temporally release neurotransmitters to modulate the immune response. instead of acting passively, oyster haemocytes were abl ...201728077596
identification of the molecular clockwork of the oyster crassostrea gigas.molecular clock system constitutes the origin of biological rhythms that allow organisms to anticipate cyclic environmental changes and adapt their behavior and physiology. components of the molecular clock are largely conserved across a broad range of species but appreciable diversity in clock structure and function is also present especially in invertebrates. the present work aimed at identify and characterize molecular clockwork components in relationship with the monitoring of valve activity ...201728072861
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