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1
Richards, Gary P., Michael A. Watson, David S. Needleman, Karlee M. Church, and Claudia C. Häse. "Mortalities of Eastern and Pacific Oyster Larvae Caused by the Pathogens Vibrio coralliilyticus and Vibrio tubiashii." Applied and Environmental Microbiology 81, no. 1 (October 24, 2014): 292–97. http://dx.doi.org/10.1128/aem.02930-14.
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ABSTRACTVibrio tubiashiiis reported to be a bacterial pathogen of larval Eastern oysters (Crassostrea virginica) and Pacific oysters (Crassostrea gigas) and has been associated with major hatchery crashes, causing shortages in seed oysters for commercial shellfish producers. Another bacterium,Vibrio coralliilyticus, a well-known coral pathogen, has recently been shown to elicit mortality in fish and shellfish. Several strains ofV. coralliilyticus, such as ATCC 19105 and Pacific isolates RE22 and RE98, were misidentified asV. tubiashiiuntil recently. We compared the mortalities caused by twoV. tubiashiiand fourV. coralliilyticusstrains in Eastern and Pacific oyster larvae. The 50% lethal dose (LD50) ofV. coralliilyticusin Eastern oysters (defined here as the dose required to kill 50% of the population in 6 days) ranged from 1.1 × 104to 3.0 × 104CFU/ml seawater; strains RE98 and RE22 were the most virulent. This study shows thatV. coralliilyticuscauses mortality in Eastern oyster larvae. Results for Pacific oysters were similar, with LD50s between 1.2 × 104and 4.0 × 104CFU/ml.Vibrio tubiashiiATCC 19106 and ATCC 19109 were highly infectious toward Eastern oyster larvae but were essentially nonpathogenic toward healthy Pacific oyster larvae at dosages of ≥1.1 × 104CFU/ml. These data, coupled with the fact that several isolates originally thought to beV. tubiashiiare actuallyV. coralliilyticus, suggest thatV. coralliilyticushas been a more significant pathogen for larval bivalve shellfish thanV. tubiashii, particularly on the U.S. West Coast, contributing to substantial hatchery-associated morbidity and mortality in recent years.
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Chiesa, Stefania, Livia Lucentini, Paula Chainho, Federico Plazzi, Maria Manuel Angélico, Francisco Ruano, Rosa Freitas, and José Lino Costa. "One in a Million: Genetic Diversity and Conservation of the Reference Crassostrea angulata Population in Europe from the Sado Estuary (Portugal)." Life 11, no. 11 (November 3, 2021): 1173. http://dx.doi.org/10.3390/life11111173.
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The production of cupped oysters is an important component of European aquaculture. Most of the production relies on the cultivation of the Pacific oyster Crassostrea gigas, although the Portuguese oyster Crassostrea angulata represents a valuable product with both cultural and economic relevance, especially in Portugal. The authors of the present study investigated the genetic diversity of Portuguese oyster populations of the Sado estuary, both from natural oyster beds and aquaculture facilities, through cox1 gene fragment sequencing. Then, a comparison with a wide dataset of cupped oyster sequences obtained from GenBank (up to now the widest available dataset in literature for the Portuguese oyster) was performed. Genetic data obtained from this work confirmed that the Pacific oyster does not occur in the natural oyster beds of the Sado estuary but showed that the species occasionally occurs in the oyster hatcheries. Moreover, the results showed that despite the founder effect and the bottleneck events that the Sado populations have experienced, they still exhibit high haplotype diversity. Risks are arising for the conservation of the Portuguese oyster reference populations of the Sado estuary due to the occurrence of the Pacific oyster in the local hatcheries. Therefore, researchers, local authorities, and oyster producers should work together to avoid the loss of this valuable resource.
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SU, YI-CHENG, QIANRU YANG, and CLAUDIA HÄSE. "Refrigerated Seawater Depuration for Reducing Vibrio parahaemolyticus Contamination in Pacific Oyster (Crassostrea gigas)." Journal of Food Protection 73, no. 6 (June 1, 2010): 1111–15. http://dx.doi.org/10.4315/0362-028x-73.6.1111.
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The efficacy of refrigerated-seawater depuration for reducing Vibrio parahaemolyticus levels in Pacific oyster (Crassostrea gigas) was investigated. Raw Pacific oysters were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (105 to 106 most probable number [MPN] per g) and depurated with refrigerated seawater (5°C) in a laboratory-scale recirculation system equipped with a 15-W gamma UV sterilizer. Depuration with refrigerated seawater for 96 h reduced V. parahaemolyticus populations by >3.0 log MPN/g in oysters harvested in the winter. However, 144 h of depuration at 5°C was required to achieve a 3-log reduction in oysters harvested in the summer. Depuration with refrigerated seawater at 5°C for up to 144 h caused no significant fatality in the Pacific oyster and could be applied as a postharvest treatment to reduce V. parahaemolyticus contamination in Pacific oysters. Further studies are needed to validate the efficacy of the depuration process for reducing naturally accumulated V. parahaemolyticus in oysters.
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Markert, Alexandra. "How dense is dense? Toward a harmonized approach to characterizing reefs of non-native Pacific oysters – with consideration of native mussels." NeoBiota 57 (May 29, 2020): 7–52. http://dx.doi.org/10.3897/neobiota.57.49196.
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Pacific oysters Crassostrea (Magallana) gigas have been successfully invading ecosystems worldwide. As an ecosystem engineer, they have the potential to substantially impact on other species and on functional processes of invaded ecosystems. Engineering strength depends on oyster density in space and time. Density has not yet been studied on the extent of reef structural dynamics. This study assessed abundance of naturalized Pacific oysters by shell length (SL) of live individuals and post-mortem shells at six sites over six consecutive years during post-establishment. Individual biomass, i.e. live wet mass (LWM), flesh mass (FM) and live shell mass (SM LIVE), were determined from a total of 1.935 live oysters in order to estimate areal biomass. The generic term density attribute was used for SL-related population categories and the biomass variables LWM, FM, SM LIVE and SM. As the oyster invasion modulated resident Mytilus edulis beds, the study was supplemented by contemporaneously assessed data of mussels and corresponding analyses. Interrelations of abundance and areal biomass revealed distinct linkages between specific density attributes. Most importantly, large individuals were identified as intrinsic drivers for the determination of areal biomass. Additionally, allometry of large oysters differed from small oysters by attenuated scaling relations. This effect was enhanced by oyster density as results showed that crowding forced large individuals into an increasing slender shape. The significant relationship between the density attributes large oyster and biomass enabled a classification of reef types by large oyster abundance. Reef type (simple or complex reef) and oyster size (small or large) were considered by implementing a novel concept of weighted twin functions (TF) for the relationship between SL and individual biomass. This study demonstrates that the interplay of scaling parameters (scalar, exponent) is highly sensitive to the estimation of individual biomass (shape) and that putative similar scaling parameters can exceedingly affect the estimation of areal biomass. For the first time, this study documents the crucial relevance of areal reference, i.e. cluster density (CD) or reef density (RD), when comparing density. RD considers reef areas devoid of oysters and results from CD reduced by reef coverage (RC) as the relative reef area occupied by oysters. A compilation of density attributes at simple and complex reefs shall serve as a density guide. Irrespective of areal reference, oyster structural density attributes were significantly higher at complex than at simple reefs. In contrast, areal reference was of vital importance when evaluating the impact of engineering strength at ecosystem-level. While mussel CD was similar at both reef types, RD at complex reefs supported significantly more large mussels and higher mussel biomass than at simple reefs. Although mussels dominated both reef types by abundance of large individuals, oysters were the keystone engineers by dominating biomass. The prominent status of large oysters for both allometric scaling and density, presumably characteristic for Pacific oyster populations worldwide, should be considered when conducting future investigations. The effort of monitoring will substantially be reduced as only large oysters have to be counted for an empirical characterization of Pacific oyster reefs. The large oyster concept is independent of sampling season, assessment method or ecosystem, and is also applicable to old data sets. Harmonization on the proposed density attributes with a clear specification of areal reference will allow trans-regional comparisons of Pacific oyster reefs and will facilitate evaluations of engineering strength, reef performance and invasional impacts at ecosystem-level.
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Qurani, Risma, Fredinan Yulianda, and Agustinus Mangaratua Samosir. "Spatial Distribution of Pacific Oyster (Crassostrea gigas) Population Related Environment Factor in Coastal Water of Pabean Ilir, Indramayu." Jurnal Moluska Indonesia 4, no. 1 (April 1, 2020): 38–47. http://dx.doi.org/10.54115/jmi.v4i1.12.
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Pacific oysters (Crassostrea gigas, Thunberg, 1793) is a benthic organisme that tend to live and settle in the bottom. One of the pacific oyster habitat is Coastal Water of Pabean Ilir, Indramayu. The purpose of this study was to map spatial condition of the population related habitat of the oyster (Crassostrea gigas). The mapping were done with laptop, using Arc GIS. There were 15 points of sampling. The oyster population in Pabean Ilir can be categorized into three categories: low, medium, and high density. Based on the similarity of environmental characteristics the habitat were divided into four groups. Condition Coastal Water of Pabean Ilir such as temperature, salinity, pH, BOD, TSS, TDS, COD, and composition of substrate indicated Coastal Water of Pabean Ilir have compatibility optimum sufficient habitat to support the growth of pacific oyster
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Nugraha, Roni, Thimo Ruethers, Aya C. Taki, Elecia B. Johnston, Shaymaviswanathan Karnaneedi, Sandip D. Kamath, and Andreas L. Lopata. "Recombinant Tropomyosin from the Pacific Oyster (Crassostrea gigas) for Better Diagnosis." Foods 11, no. 3 (January 30, 2022): 404. http://dx.doi.org/10.3390/foods11030404.
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The Pacific oyster is a commercially important mollusc and, in contrast to most other shellfish species, frequently consumed without prior heat treatment. Oysters are rich in many nutrients but can also cause food allergy. Knowledge of their allergens and cross-reactivity remains very limited. These limitations make an optimal diagnosis of oyster allergy difficult, in particular to the Pacific oyster (Crassostrea gigas), the most cultivated and consumed oyster species worldwide. This study aimed to characterise IgE sensitisation profiles of 21 oyster-sensitised patients to raw and heated Pacific oyster extract using immunoblotting and advanced mass spectrometry, and to assess the relevance of recombinant oyster allergen for improved diagnosis. Tropomyosin was identified as the major allergen recognised by IgE from 18 of 21 oyster-sensitised patients and has been registered with the WHO/IUIS as the first oyster allergen (Cra g 1). The IgE-binding capacity of oyster-sensitised patients’ IgE to purified natural and recombinant tropomyosin from oyster, prawn, and dust mite was compared using enzyme-linked immunosorbent assay. The degree of IgE binding varied between patients, indicating partial cross-sensitisation and/or co-sensitisation. Amino acid sequence alignment of tropomyosin from these three species revealed five regions that contain predicted IgE-binding epitopes, which are most likely responsible for this cross-reactivity. This study fully biochemically characterises the first and major oyster allergen Cra g 1 and demonstrates that the corresponding recombinant tropomyosin should be implemented in improved component-resolved diagnostics and guide future immunotherapy.
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Mikac, Barbara, Alessandro Tarullo, Marina Antonia Colangelo, Marco Abbiati, and Federica Costantini. "Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia." Diversity 13, no. 11 (October 23, 2021): 526. http://dx.doi.org/10.3390/d13110526.
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Oyster shells are substratum for different epibiontic and endobiontic organisms, including pests and parasites. Rocellaria dubia is endolithic and facultative tube-dwelling bivalve, boring in different calcareous substrates, including the shells of bivalves. In 2020, R. dubia was found as endolithic in the shells of the Pacific oyster Magalana gigas, from an oyster farm off the Sacca di Goro lagoon (Emilia-Romagna region, Northern Adriatic Sea, Italy). The purpose of this study was to describe this newly recorded association. Altogether, 136 specimens of R. dubia were found in 15 oysters, photographed under a stereoscope, and their length was measured. Heavily infested oysters hosted tens of R. dubia borers, which were perforating the whole thickness of the oyster valves. The flesh of these oysters was heavily damaged, suggesting parasitic association. R. dubia specimens were categorized into three age classes (0–1, 1–2, and 2–3 years old). M. gigas/R. dubia might be a widespread association, overlooked due to the very scarce research on macrofauna associated with M. gigas. Considering the negative effects of R. dubia endobiosis on oyster fitness, and possible impacts on oyster aquaculture, further research should be conducted in order to elucidate the distribution and ecological characteristics of this parasitic association.
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Boullot, Floriane, Caroline Fabioux, Hélène Hégaret, Pierre Boudry, Philippe Soudant, and Evelyne Benoit. "Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin." Marine Drugs 19, no. 7 (June 30, 2021): 380. http://dx.doi.org/10.3390/md19070380.
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Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.
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Li, Xing-Xia, Wen-Chao Yu, Zhong-Qiang Cai, Cheng He, Na Wei, Xiao-Tong Wang, and Xi-Qing Yue. "Molecular Cloning and Characterization of Full-Length cDNA of Calmodulin Gene from Pacific OysterCrassostrea gigas." BioMed Research International 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/5986519.
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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 different shell formation mechanisms among mollusks. We cloned the full-length cDNA of Pacific oyster CaM (cgCaM) and found that the cgCaM ORF encoded a peptide of 113 amino acids containing three EF-hand calcium-binding domains, its expression level was highest in the mantle, hinting that the cgCaM gene is probably involved in shell formation of Pacific oyster, and the common ancestor of Gastropoda and Bivalvia may possess at least three CaM genes. We also found that the numbers of some EF hand family members in highly calcified species were higher than those in lowly calcified species and the numbers of these motifs in oyster genome were the highest among the mollusk species with whole genome sequence, further hinting the correlation between CaM and biomineralization.
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ARAI, SAKURA, SATOKO YAMAYA, KAYOKO OHTSUKA, NORIKO KONISHI, HIROMI OBATA, TADASUKE OOKA, SHOUHEI HIROSE, AKEMI KAI, and YUKIKO HARA-KUDO. "Detection of Escherichia albertii in Retail Oysters." Journal of Food Protection 85, no. 1 (September 30, 2021): 173–79. http://dx.doi.org/10.4315/jfp-21-222.
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ABSTRACT Escherichia albertii is an emerging foodborne pathogen. Owing to its distribution in river water, it is important to determine the presence of E. albertii in aquaculture-related foods. In this study, we investigated the distribution of E. albertii in retail oyster samples. A total of 427 raw oyster samples (385 Pacific oysters and 42 Japanese rock oysters) were enriched in modified Escherichia coli broth (mEC) or mEC supplemented with novobiocin (NmEC) at 42°C. The cultures were used for E. albertii–specific nested PCR assay, as well as for E. albertii isolation using deoxycholate hydrogen sulfide lactose agar (DHL), DHL supplemented with rhamnose and xylose, and MacConkey agar supplemented with rhamnose and xylose. The population of E. albertii in nested PCR-positive samples was determined using the most-probable-number (MPN) method. E. albertii isolates were subjected to biochemical and genetic characterization. E. albertii was detected in 5 (1.6%) of 315 Pacific oyster samples (one piece each), 2 (2.9%) of 70 Pacific oyster samples (25 g each), and 2 (4.8%) of 42 Japanese rock oyster samples procured from four geographically distinct regions. A total of 64 E. albertii strains were isolated from eight of the nine nested PCR assay–positive oyster samples, and the MPN value was under the detection limit (<3 MPN/10 g). A specific season or month for detecting E. albertii was not observed in this study, suggesting that the pathogen is present in seawater. All the E. albertii isolates, except one, were positive for the virulence factor eae, indicating that these isolates have the potential to infect humans. HIGHLIGHTS
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Agnew, M. Victoria, Carolyn S. Friedman, Christopher Langdon, Konstantin Divilov, Blaine Schoolfield, Benjamin Morga, Lionel Degremont, et al. "Differential Mortality and High Viral Load in Naive Pacific Oyster Families Exposed to OsHV-1 Suggests Tolerance Rather than Resistance to Infection." Pathogens 9, no. 12 (December 17, 2020): 1057. http://dx.doi.org/10.3390/pathogens9121057.
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Pacific oysters, Crassostrea gigas, are one of the most productive aquaculture species in the world. However, they are threatened by the spread of Ostreid herpesvirus-1 (OsHV-1) and its microvariants (collectively “µvars”), which cause mass mortalities in all life stages of Pacific oysters globally. Breeding programs have been successful in reducing mortality due to OsHV-1 variants following viral outbreaks; however, an OsHV-1-resistant oyster line does not yet exist in the United States (US), and it is unknown how OsHV-1 µvars will affect US oyster populations compared to the current variant, which is similar to the OsHV-1 reference, found in Tomales Bay, CA. The goals of this study were to investigate the resistance of C. gigas juveniles produced by the Molluscan Broodstock Program (MBP) to three variants of OsHV-1: a California reference OsHV-1, an Australian µvar, and a French µvar. This is the first study to directly compare OsHV-1 µvars to a non-µvar. The survival probability of oysters exposed to the French (FRA) or Australian (AUS) µvar was significantly lower (43% and 71%, respectively) than to the reference variant and controls (96%). No oyster family demonstrated resistance to all three OsHV-1 variants, and many surviving oysters contained high copy numbers of viral DNA (mean ~3.53 × 108). These results indicate that the introduction of OsHV-1 µvars could have substantial effects on US Pacific oyster aquaculture if truly resistant lines are not achieved, and highlight the need to consider resistance to infection in addition to survival as traits in breeding programs to reduce the risk of the spread of OsHV-1 variants.
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Lapègue, Sylvie, Serge Heurtebise, Florence Cornette, Erwan Guichoux, and Pierre-Alexandre Gagnaire. "Genetic Characterization of Cupped Oyster Resources in Europe Using Informative Single Nucleotide Polymorphism (SNP) Panels." Genes 11, no. 4 (April 21, 2020): 451. http://dx.doi.org/10.3390/genes11040451.
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The Pacific oyster, Crassostrea gigas, was voluntarily introduced from Japan and British Columbia into Europe in the early 1970s, mainly to replace the Portuguese oyster, Crassostrea angulata, in the French shellfish industry, following a severe disease outbreak. Since then, the two species have been in contact in southern Europe and, therefore, have the potential to exchange genes. Recent evolutionary genomic works have provided empirical evidence that C. gigas and C. angulata exhibit partial reproductive isolation. Although hybridization occurs in nature, the rate of interspecific gene flow varies across the genome, resulting in highly heterogeneous genome divergence. Taking this biological property into account is important to characterize genetic ancestry and population structure in oysters. Here, we identified a subset of ancestry-informative makers from the most differentiated regions of the genome using existing genomic resources. We developed two different panels in order to (i) easily differentiate C. gigas and C. angulata, and (ii) describe the genetic diversity and structure of the cupped oyster with a particular focus on French Atlantic populations. Our results confirm high genetic homogeneity among Pacific cupped oyster populations in France and reveal several cases of introgressions between Portuguese and Japanese oysters in France and Portugal.
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Ramadhaniaty, M., C. Octavina, FA Putri, S. Karina, and Ichsan. "The density and distribution of Pacific Oyster (Crassostrea gigas) in Krueng Cut, Aceh Besar." IOP Conference Series: Earth and Environmental Science 869, no. 1 (November 1, 2021): 012056. http://dx.doi.org/10.1088/1755-1315/869/1/012056.
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Abstract Crassostrea gigas is a Pacific oyster that has the largest size among the other oysters. This oyster is most often found because of its ability to adapt to a variety of environments. Krueng Cut is an estuary area that gets a lot of nutrient input from sea water because it is directly adjacent to the ocean. This condition makes this area has a high abundance of oysters with high fishing and antropogenic activities as well. The purpose of this study was to determine the density and distribution of the oyster population from 3 representative stations along the estuary area of Krueng Cut. The method used in this study is random sampling using a quadratic transect. The results show that the highest density is indicated by station 3 with 55.67 ind/m2 and the lowest density is indicated by station 1 is 40.33 ind/m2. These results indicate that the activities of residents, the entry of contaminants from antropogenic affect the density of oysters. The distribution of oysters from the three stations showed similarities, namely they tended to grouping. The aquatic environment at the three research stations still supports the growth of oysters. This study confirms that there has been a decline in the population, which is characterized by a decrease in the number of catches and a smaller size of oysters.
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FERNANDEZ-PIQUER, JUDITH, JOHN P. BOWMAN, TOM ROSS, SILVIA ESTRADA-FLORES, and MARK L. TAMPLIN. "Preliminary Stochastic Model for Managing Vibrio parahaemolyticus and Total Viable Bacterial Counts in a Pacific Oyster (Crassostrea gigas) Supply Chain." Journal of Food Protection 76, no. 7 (July 1, 2013): 1168–78. http://dx.doi.org/10.4315/0362-028x.jfp-12-401.
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Vibrio parahaemolyticus can accumulate and grow in oysters stored without refrigeration, representing a potential food safety risk. High temperatures during oyster storage can lead to an increase in total viable bacteria counts, decreasing product shelf life. Therefore, a predictive tool that allows the estimation of both V. parahaemolyticus populations and total viable bacteria counts in parallel is needed. A stochastic model was developed to quantitatively assess the populations of V. parahaemolyticus and total viable bacteria in Pacific oysters for six different supply chain scenarios. The stochastic model encompassed operations from oyster farms through consumers and was built using risk analysis software. Probabilistic distributions and predictions for the percentage of Pacific oysters containing V. parahaemolyticus and high levels of viable bacteria at the point of consumption were generated for each simulated scenario. This tool can provide valuable information about V. parahaemolyticus exposure and potential control measures and can help oyster companies and regulatory agencies evaluate the impact of product quality and safety during cold chain management. If coupled with suitable monitoring systems, such models could enable preemptive action to be taken to counteract unfavorable supply chain conditions.
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Renault, Tristan, Anne Lise Bouquet, Julien-Thomas Maurice, Coralie Lupo, and Philippe Blachier. "Ostreid Herpesvirus 1 Infection among Pacific Oyster (Crassostrea gigas) Spat: Relevance of Water Temperature to Virus Replication and Circulation Prior to the Onset of Mortality." Applied and Environmental Microbiology 80, no. 17 (June 27, 2014): 5419–26. http://dx.doi.org/10.1128/aem.00484-14.
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ABSTRACTA number of bivalve species worldwide, including the Pacific oyster,Crassostrea gigas, have been affected by mass mortality events associated with herpesviruses, resulting in significant losses. A particular herpesvirus was purified from naturally infected larval Pacific oysters, and its genome was completely sequenced. This virus has been classified asOstreid herpesvirus 1(OsHV-1) within the familyMalacoherpesviridae. Since 2008, mass mortality outbreaks amongC. gigasin Europe have been related to the detection of a variant of OsHV-1 called μVar. Additional data are necessary to better describe mortality events in relation to environmental-parameter fluctuations and OsHV-1 detection. For this purpose, a single batch of Pacific oyster spat was deployed in 4 different locations in the Marennes-Oleron area (France): an oyster pond (“claire”), a shellfish nursery, and two locations in the field. Mortality rates were recorded based on regular observation, and samples were collected to search for and quantify OsHV-1 DNA by real-time PCR. Although similar massive mortality rates were reported at the 4 sites, mortality was detected earlier in the pond and in the nursery than at both field sites. This difference may be related to earlier increases in water temperature. Mass mortality was observed among oysters a few days after increases in the number of PCR-positive oysters and viral-DNA amounts were recorded. An initial increment in the number of PCR-positive oysters was reported at both field sites during the survey in the absence of significant mortality. During this period, the water temperature was below 16°C.
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Lyu, Chenang, Jingwen Li, Zhentao Shi, Ran An, Yanfei Wang, Guangda Luo, and Dapeng Wang. "Identification of Potential Proteinaceous Ligands of GI.1 Norovirus in Pacific Oyster Tissues." Viruses 15, no. 3 (February 25, 2023): 631. http://dx.doi.org/10.3390/v15030631.
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Human norovirus (HuNoV) is the leading foodborne pathogen causing nonbacterial gastroenteritis worldwide. The oyster is an important vehicle for HuNoV transmission, especially the GI.1 HuNoV. In our previous study, oyster heat shock protein 70 (oHSP 70) was identified as the first proteinaceous ligand of GII.4 HuNoV in Pacific oysters besides the commonly accepted carbohydrate ligands, a histo-blood group antigens (HBGAs)-like substance. However the mismatch of the distribution pattern between discovered ligands and GI.1 HuNoV suggests that other ligands may exist. In our study, proteinaceous ligands for the specific binding of GI.1 HuNoV were mined from oyster tissues using a bacterial cell surface display system. Fifty-five candidate ligands were identified and selected through mass spectrometry identification and bioinformatics analysis. Among them, the oyster tumor necrosis factor (oTNF) and oyster intraflagellar transport protein (oIFT) showed strong binding abilities with the P protein of GI.1 HuNoV. In addition, the highest mRNA level of these two proteins was found in the digestive glands, which is consistent with GI.1 HuNoV distribution. Overall the findings suggested that oTNF and oIFT may play important roles in the bioaccumulation of GI.1 HuNoV.
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TAKAHASHI, MICHIKO, YUMIKO OKAKURA, HAJIME TAKAHASHI, HISAYA YAMANE, SATORU AKASHIGE, TAKASHI KUDA, and BON KIMURA. "Evaluation of Inactivation of Murine Norovirus in Inoculated Shell Oysters by High Hydrostatic Pressure Treatment." Journal of Food Protection 82, no. 12 (November 19, 2019): 2169–73. http://dx.doi.org/10.4315/0362-028x.jfp-19-186.
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ABSTRACT One of the major foods causing norovirus gastroenteritis is bivalve shellfish, such as oysters. Depuration and relaying methods have been used to control norovirus. However, these methods may be inadequate to control norovirus gastroenteritis. The present study aimed to investigate the effectiveness of high hydrostatic pressure (HHP) treatment in controlling norovirus in shelled oysters, by evaluating the inactivating effect of HHP on murine norovirus strain 1 (MNV-1) inoculated into a buffer, oyster homogenate, and shelled oysters. First, MNV-1 was inoculated (infectivity of 4.5 log PFU/mL) into the buffer and oyster homogenate, with a pH of 6.3 and salinity (NaCl) of 1.5%, mimicking the habitats of the Pacific oyster (Crassostrea gigas). HHP treatment at 100, 200, 275, and 300 MPa for 2 and 5 min was conducted at an initial temperature of 0 or 5°C. The infectivity of MNV-1 in both the buffer and the oyster homogenate was lower when the initial temperature was 0°C. In the buffer, the infectivity of MNV-1 decreased to 1.8 log PFU/mL after HHP treatment (200 MPa for 5 min at 0°C), and the inactivating effect was higher in the buffer than in the oyster homogenate. MNV-1 was inoculated into shelled oysters (4.8 log PFU per oyster), and HHP treatment was done at 275, 300, and 350 MPa for 5 min at the initial temperature of 0°C. The infectivity of MNV-1 decreased to 2.8 log PFU per oyster after HHP treatment at 275 MPa for 5 min. The results indicate that the inactivating effect of HHP treatment varies, depending on the medium surrounding the viral particles. Inactivation was best in buffer, followed by oyster homogenate and shelled oysters. The data could inform the development of methods to control norovirus in oysters. HIGHLIGHTS
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Potts, Robert W. A., Alejandro P. Gutierrez, Yennifer Cortés-Araya, Ross D. Houston, and Tim P. Bean. "Developments in marine invertebrate primary culture reveal novel cell morphologies in the model bivalve Crassostrea gigas." PeerJ 8 (June 1, 2020): e9180. http://dx.doi.org/10.7717/peerj.9180.
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Cell culture provides useful model systems used in a wide range of biological applications, but its utility in marine invertebrates is limited due to the lack of immortalised cell lines. Primary cell and tissue cultures are typically used but remain poorly characterised for oysters, which can cause issues with experimental consistency and reproducibility. Improvements to methods of repeatable isolation, culture, and characterisation of oyster cells and tissues are required to help address these issues. In the current study, systematic improvements have been developed to facilitate the culture of primary cells from adult Pacific oyster tissues and identify novel cell morphologies that have not been reported previously. Cultures analysed by light microscopy, qPCR, and live cell imaging demonstrated maintenance of live, metabolically active Pacific oyster cells for several weeks post-explant. Interestingly, whole hearts dissected from adult oysters were found to continue contracting rhythmically up to 8 weeks after being transferred to a tissue culture system. Mantle tissue explants were also actively moving in the culture system. These improvements in primary cell culture of bivalves may be beneficial for research in ecotoxicology, virology, immunology, and genetic resistance to disease.
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Aagesen, Alisha M., Sureerat Phuvasate, Yi-Cheng Su, and Claudia C. Häse. "Persistence of Vibrio parahaemolyticus in the Pacific Oyster, Crassostrea gigas, Is a Multifactorial Process Involving Pili and Flagella but Not Type III Secretion Systems or Phase Variation." Applied and Environmental Microbiology 79, no. 10 (March 8, 2013): 3303–5. http://dx.doi.org/10.1128/aem.00314-13.
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ABSTRACTVibrio parahaemolyticuscan resist oyster depuration, suggesting that it possesses specific factors for persistence. We show that type I pili, type IV pili, and both flagellar systems contribute toV. parahaemolyticuspersistence in Pacific oysters whereas type III secretion systems and phase variation do not.
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Dhanji-Rapkova, Monika, Andrew D. Turner, Craig Baker-Austin, Jim F. Huggett, and Jennifer M. Ritchie. "Distribution of Tetrodotoxin in Pacific Oysters (Crassostrea gigas)." Marine Drugs 19, no. 2 (February 2, 2021): 84. http://dx.doi.org/10.3390/md19020084.
Full textAbstract:
A potent and heat-stable tetrodotoxin (TTX) has been found to accumulate in various marine bivalve species, including Pacific oysters (Crassostrea gigas), raising a food safety concern. While several studies on geographical occurrence of TTX have been conducted, there is a lack of knowledge about the distribution of the toxin within and between bivalves. We, therefore, measured TTX in the whole flesh, mantle, gills, labial palps, digestive gland, adductor muscle and intravalvular fluid of C. gigas using liquid chromatography-tandem mass spectrometry. Weekly monitoring during summer months revealed the highest TTX concentrations in the digestive gland (up to 242 µg/kg), significantly higher than in other oyster tissues. Intra-population variability of TTX, measured in the whole flesh of each of twenty animals, reached 46% and 32% in the two separate batches, respectively. In addition, an inter-population study was conducted to compare TTX levels at four locations within the oyster production area. TTX concentrations in the whole flesh varied significantly between some of these locations, which was unexplained by the differences in weight of flesh. This is the first study examining TTX distribution in C. gigas and the first confirmation of the preferential accumulation of TTX in oyster digestive gland.
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ABEYTA, CARLOS, FRANK G. DEETER, CHARLES A. KAYSNER, ROBERT F. STOTT, and MARLEEN M. WEKELL. "Campylobacter jejuni in a Washington State Shellfish Growing Bed Associated With Illness." Journal of Food Protection 56, no. 4 (April 1, 1993): 323–25. http://dx.doi.org/10.4315/0362-028x-56.4.323.
Full textAbstract:
Consumption of raw Pacific oysters (Crassotea gigas) harvested from a Washington State recreational shellfish bed were associated with illness. Illness occurred within 2 d of ingestion of a half-dozen shellstock oysters. Each oyster consist of approximately 20 g of meat. The duration of illness lasted 2 d. Routinely, Campylobacter species have been found in several shellfish beds in the Puget Sound Bay. Its presence in the marine environment appears to be incidental and primarily, comes from wild birds, farm runoff, and sewage bypasses. This paper describes the first reported case of Campylobacter gastroenteritis associated with raw oyster consumption in the State of Washington.
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Vyalova, O. Yu. "Growth and terms of obtaining marketable triploid oysters in Donuzlav Liman (Black Sea, Crimea)." Marine Biological Journal 4, no. 1 (March 31, 2019): 24–32. http://dx.doi.org/10.21072/mbj.2019.04.1.03.
Full textAbstract:
The rate of linear and weight growth of triploid spat of oyster Crassostrea gigas in Donuzlav Liman (Black Sea, Crimea) was investigated. A quantitative relationship between the mass (W, g) of the whole oyster and the height of the shell (H, mm) is given (it is described by the equation W = 7 · 10-5 · Н3.1, R² = 0.78), as well as a quantitative relationship between the mass (W, g) of the whole oyster and the length of the shell (L, mm) (W = 3 · 10-4 · L3.12, R² = 0.65). The maximum rates of linear growth of triploid oysters T20 were registered in April (1.15 mm per day), of weight growth – in June (0.50 g per day) and August (0.61 g per day). It was shown that 27 % of triploid oysters T20 can reach commercial size after 6 months. It is recommended to use Pacific oysters of T20 size as a planting material on the shellfish farms in the Black Sea region.
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Cruz, C. D., D. Hedderley, and G. C. Fletcher. "Long-Term Study of Vibrio parahaemolyticus Prevalence and Distribution in New Zealand Shellfish." Applied and Environmental Microbiology 81, no. 7 (January 23, 2015): 2320–27. http://dx.doi.org/10.1128/aem.04020-14.
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ABSTRACTThe food-borne pathogenVibrio parahaemolyticushas been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence ofV. parahaemolyticusin NZ oysters and Greenshell mussels and the prevalence ofV. parahaemolyticustdhandtrhstrains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. TotalV. parahaemolyticusnumbers and the presence of pathogenic genestdhandtrhwere determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ,V. parahaemolyticuswas detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers ofV. parahaemolyticustdhandtrhstrains were low, with just 3/215 Pacific oyster samples carrying thetdhgene.V. parahaemolyticusorganisms carryingtdhandtrhwere not detected in South Island samples, andV. parahaemolyticuswas detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers ofV. parahaemolyticusorganisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers ofV. parahaemolyticusorganisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the totalV. parahaemolyticusnumbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly.
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Kornbluth, Aaron, Bryce D. Perog, Samantha Crippen, Danielle Zacherl, Brandon Quintana, Edwin D. Grosholz, and Kerstin Wasson. "Mapping oysters on the Pacific coast of North America: A coast-wide collaboration to inform enhanced conservation." PLOS ONE 17, no. 3 (March 17, 2022): e0263998. http://dx.doi.org/10.1371/journal.pone.0263998.
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To conserve coastal foundation species, it is essential to understand patterns of distribution and abundance and how they change over time. We synthesized oyster distribution data across the west coast of North America to develop conservation strategies for the native Olympia oyster (Ostrea lurida), and to characterize populations of the non-native Pacific oyster (Magallana gigas). We designed a user-friendly portal for data entry into ArcGIS Online and collected oyster records from unpublished data submitted by oyster experts and from the published literature. We used the resulting 2,000+ records to examine spatial and temporal patterns and made an interactive web-based map publicly available. Comparing records from pre-2000 vs. post-2000, we found that O. lurida significantly decreased in abundance and distribution, while M. gigas increased significantly. Currently the distribution and abundance of the two species are fairly similar, despite one species being endemic to this region since the Pleistocene, and the other a new introduction. We mapped the networks of sites occupied by oysters based on estimates of larval dispersal distance, and found that these networks were larger in Canada, Washington, and southern California than in other regions. We recommend restoration to enhance O. lurida, particularly within small networks, and to increase abundance where it declined. We also recommend restoring natural biogenic beds on mudflats and sandflats especially in the southern range, where native oysters are currently found most often on riprap and other anthropogenic structures. This project can serve as a model for collaborative mapping projects that inform conservation strategies for imperiled species or habitats.
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TIAN, PENG, ANNA L. ENGELBREKTSON, and ROBERT E. MANDRELL. "Seasonal Tracking of Histo-Blood Group Antigen Expression and Norovirus Binding in Oyster Gastrointestinal Cells." Journal of Food Protection 71, no. 8 (August 1, 2008): 1696–700. http://dx.doi.org/10.4315/0362-028x-71.8.1696.
Full textAbstract:
Noroviruses (NORs) are the most common cause of viral gastroenteritis outbreaks. Outbreaks are often associated with the consumption of contaminated oysters and generally occur between the months of November and March, when oysters produce the highest levels of glycogen. Oyster glycogen has been proposed as playing a role in NOR accumulation. Recent research indicates that histo-blood group antigens (HBGAs) function as viral receptors on human gastrointestinal cells. In this study, oyster glycogen was tested to determine whether it contains HBGA-like molecules and whether it plays a role in NOR binding. The correlation between the amount of HBGA expression and NOR binding also was measured. We also tested whether seasonal changes affected HBGA expression and binding of recombinant NORs. The results indicate that recombinant NOR binding is highly correlated with HBGA expression in Virginica (Crassostrea virginica), Pacific (Crassostrea gigas), and Kumamato (Crassostrea sikamea) oysters, but the association does not have a seasonal pattern. No obvious trend in either HBGA expression or recombinant NOR binding by month was noted. A significant increase in recombinant NOR binding was observed in Virginica and Pacific oysters in a season not generally associated with NOR gastroenteritis outbreaks. A significant increase in HBGA expression also was observed for Pacific and Virginica oysters in the same season. Paradoxically, HBGA expression and NOR binding both were higher in oysters produced in the non–NOR gastroenteritis season (April through October) than in those produced in the NOR gastroenteritis season (November through March), suggesting that seasonal NOR gastroenteritis outbreaks are not associated with high levels of HBGA expression or NOR binding.
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Batley, GE, C. Fuhua, CI Brockbank, and KJ Flegg. "Accumulation of Tributyltin by the Sydney Rock Oyster, Saccostrea commercialis." Marine and Freshwater Research 40, no. 1 (1989): 49. http://dx.doi.org/10.1071/mf9890049.
Full textAbstract:
Tributyltin (TBT) concentrations have been measured in the tissue of the Sydney rock oyster Saccostrea commercialis sampled from estuaries in New South Wales, Australia. Background TBT levels of below 2 ng Sn g-1 contrasted with values between 80 and 130 ng Sn g-1 in oysters exposed to high boat densities or poor tidal flushing. Shell deformities and reduced tissue weights were associated with all samples displaying elevated TBT levels. Specimens of the Pacific oyster, Crassostrea gigas, growing on the same racks displayed 2-3 times the TBT concentrations of S. commercialis.
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Sakamaki, T., K. Hayashi, Y. Zheng, M. Fujibayashi, and O. Nishimura. "Effects of oyster age on selective suspension-feeding and the chemical composition of biodeposits: insights from fatty acid analysis." Marine Ecology Progress Series 644 (June 25, 2020): 75–89. http://dx.doi.org/10.3354/meps13359.
Full textAbstract:
The study objective was to clarify how the growth stages of the Pacific oyster Crassostrea gigas affect selective suspension-feeding of particulate organic matter (POM) and the composition of biodeposits. A day-long (22 h), continuous-flow mesocosm experiment was conducted with 3, 15, and 27 mo old oysters. The suspended particulate matter (PM), settled PM (mostly biodeposits in the oyster mesocosms), and oyster soft tissues were analysed to determine the content of fatty acids, organic carbon, and nitrogen, as well as the carbon and nitrogen stable isotope ratios to trace compositional changes in POM through oyster biodeposition. Regardless of oyster age, the stable isotope ratios of biodeposits were similar to those of the body tissues but not to those of the suspended PM, indicating that oysters selectively fed on assimilable fractions of POM. Compared with the suspended PM, a higher concentration of long-chain polyunsaturated fatty acids was found in the body tissues and, consequently, in the biodeposits; in contrast, the concentrations of shorter-chain fatty acids were generally lower in the biodeposits. Furthermore, the biodeposits produced by the older oysters had higher carbon, nitrogen, and fatty acid contents compared with the biodeposits produced by the 3 mo old oysters. The oxygen consumption rate of biodeposits was positively related to organic carbon content, but less so to fatty acid composition. Our findings demonstrate that older oysters not only produce larger amounts of biodeposits, but that these biodeposits have higher organic and fatty acid contents, potentially exhibiting greater effects on biogeochemical and ecological processes in nearby benthic habitats.
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Pernet, Fabrice, Sonia Gachelin, Jean-Yves Stanisière, Bruno Petton, Elodie Fleury, and Joseph Mazurié. "Farmer monitoring reveals the effect of tidal height on mortality risk of oysters during a herpesvirus outbreak." ICES Journal of Marine Science 76, no. 6 (April 24, 2019): 1816–24. http://dx.doi.org/10.1093/icesjms/fsz074.
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Abstract The intertidal zone is characterized by a sharp vertical gradient of environmental stress, which structures species distribution and their interactions. Few studies, however, have examined the influence of tidal height on host–pathogen interactions. Here, we investigated how the tidal height influence outbreak of the Ostreid herpesvirus type 1 (OsHV-1) affecting the Pacific oyster. A volunteer network composed of 20 oyster growers monitored the survival of 28 batches of oysters during an epizootic event in Southern Brittany, France. Oysters were spat from wild collection or hatchery production. The sampling sites were spread over a 150-km2 area with a tidal height ranging from 0.98 to 2.90 m. Concomitantly, we followed survival of oyster spats in relation with OsHV-1 DNA detection at two sites and conducted risk analysis. We found that tidal height was associated with a lower risk of mortality. This effect was higher for hatchery than for wild oysters probably reflecting differences in health status. Our study opens perspectives for mitigation strategies based on tidal height and emphasizes the value of volunteer science in marine epidemiological studies.
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Rupnik, Agnieszka, William Doré, Leon Devilly, James Fahy, Amy Fitzpatrick, Wiebke Schmidt, Kevin Hunt, Francis Butler, and Sinéad Keaveney. "Evaluation of Norovirus Reduction in Environmentally Contaminated Pacific Oysters During Laboratory Controlled and Commercial Depuration." Food and Environmental Virology 13, no. 2 (March 2, 2021): 229–40. http://dx.doi.org/10.1007/s12560-021-09464-2.
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AbstractNorovirus contamination of oysters is the lead cause of non-bacterial gastroenteritis and a significant food safety concern for the oyster industry. Here, norovirus reduction from Pacific oysters (Crassostrea gigas), contaminated in the marine environment, was studied in laboratory depuration trials and in two commercial settings. Norovirus concentrations were measured in oyster digestive tissue before, during and post-depuration using the ISO 15216-1 quantitative real-time RT-PCR method. Results of the laboratory-based studies demonstrate that statistically significant reductions of up to 74% of the initial norovirus GII concentration was achieved after 3 days at 17–21 °C and after 4 days at 11–15 °C, compared to 44% reduction at 7–9 °C. In many trials norovirus GII concentrations were reduced to levels below 100 genome copies per gram (gcg−1; limit of quantitation; LOQ). Virus reduction was also assessed in commercial depuration systems, routinely used by two Irish oyster producers. Up to 68% reduction was recorded for norovirus GI and up to 90% for norovirus GII reducing the geometric mean virus concentration close to or below the LOQ. In both commercial settings there was a significant difference between the levels of reduction of norovirus GI compared to GII (p < 0.05). Additionally, the ability to reduce the norovirus concentration in oysters to < LOQ differed when contaminated with concentrations below and above 1000 gcg−1. These results indicate that depuration, carried out at elevated (> 11 °C) water temperatures for at least 3 days, can reduce the concentration of norovirus in oysters and therefore consumer exposure providing a practical risk management tool for the shellfish industry.
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Li, Yan, Jian G. Qin, Catherine A. Abbott, Xiaoxu Li, and Kirsten Benkendorff. "Synergistic impacts of heat shock and spawning on the physiology and immune health ofCrassostrea gigas: an explanation for summer mortality in Pacific oysters." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 293, no. 6 (December 2007): R2353—R2362. http://dx.doi.org/10.1152/ajpregu.00463.2007.
Full textAbstract:
Mass mortality is often observed in cultured oysters during the period following spawning in the summer season. To examine the underlying causes leading to this phenomenon, thermotolerance of the Pacific oyster Crassostrea gigas was assessed using pre- and postspawning oysters that were sequentially treated with sublethal (37°C) and lethal heat shocks (44°C). The effects were examined on a range of immune and metabolic parameters in addition to mortality rate. A preventative 37°C significantly reduced oyster mortality after exposure to a second heat shock of 44°C, but in postspawning oysters mortality remained at 80%, compared with < 10% in prespawning oysters. Levels of the 72 kDa and 69 kDa heat shock proteins were low in the gill tissue from postspawning oysters stimulated by heat shock, indicating spawning reduced heat shock protein synthesis. The postspawning oysters had depleted glycogen stores in the mantle tissue and reduced adenylate energy charge after heat shock, indicative of lower energy for metabolic activity. A cumulative effect of spawning and heat shock was observed on the immunocompetence of oysters, demonstrated by reduced hemocyte phagocytosis and hemolymph antimicrobial activity. These results support the hypothesis that the energy expended during reproduction compromises the thermotolerance and immune status of oysters, leaving them easily subject to mortality if heat stress occurs in postspawning stage. This study improves our understanding of oyster summer mortality and has implications for the long-term persistence of mollusks under the influence of global warming.
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Grano-Maldonado, M. I., F. Rubalcava-Ramirez, A. Rodriguez-Santiago, F. Garcia-Vargas, A. Medina-Jasso, and M. Nieves-Soto. "First record of Stephanostomum sp. Looss, 1899 (Digenea: Acanthocolpidae) metacercariae parasitising the pleasure oyster Crassostrea corteziensis (Hertlein) from the Mexican Pacific coast." Helminthologia 56, no. 3 (September 1, 2019): 211–18. http://dx.doi.org/10.2478/helm-2019-0019.
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SummaryThe aim of this investigation was to identify the parasites present in the largely understudied pleasure oyster Crassostrea corteziensis in Sinaloa state in the northwestern Mexican Pacific coast. Inspection of twenty-eight oysters collected on “Ceuta” lagoon revealed the presence of the digenean Stephanostomum sp. (Digenea: Acanthocolpidae) cysts. Metacercariae were found encapsulated and embedded in the digestive gland and mantle tissue of oysters. The prevalence of infection revealed that 84.6 % were infected, the abundance was 13.62, with a mean intensity of 16.09 per host. The members of this genus are characterized by a double crown of spines in the cephalic region surrounding the buccal opening of the worm. Significantly, we report the first incidence of the digenean Stephanostomum sp of the family Acanthocolpidae parasitizing Crassostrea corteziensis. Further we report that this bivalve is now considered a new intermediate host, and the northwestern Mexican Pacific coast is a new geographical distribution area for this digenean. The findings contribute to our understanding of the biology, biodiversity and host preference of these parasites, with implications for health risks posed by human consumption of the pleasure oyster.
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Steele, S., and M. F. Mulcahy. "Gametogenesis of the oyster Crassostrea gigas in southern Ireland." Journal of the Marine Biological Association of the United Kingdom 79, no. 4 (August 1999): 673–86. http://dx.doi.org/10.1017/s0025315498000836.
Full textAbstract:
The Pacific oyster Crassostrea gigas (Mollusca: Bivalvia) was introduced to Ireland in 1965 and is farmed at many sites around the coast. The reproductive biology of 1377 oysters from two sites on the south coast of Ireland was examined from April 1996 until December 1997 for variations in maturation rate and condition indices. Qualitative data were compiled by staging gonadal development using histological sections. Environmental parameters of temperature, dissolved oxygen and chlorophyll-a levels, as well as parasites and pathology were monitored. Unusually high sea temperatures led to oysters in Dungarvan (site 1) spawning in both years of the study. Although sea temperatures were significantly higher, oysters in Cork Harbour (site 2) did not spawn but instead reached ripeness and then started a process of gametic degeneration called resorption. Lack of spawning was not attributed to environmental conditions monitored but was tentatively attributed to levels of pollutants in the water. Oyster condition in Cork Harbour was significantly affected by the presence of blistering due to tributyltin levels in the water and also by Polydora sp. (Polychaete) in the shell. Oyster condition in Dungarvan was not affected by the presence of the exotic species Mytilicola orientalis (Copepoda: Cyclopoida).
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Mason, CJ, and JA Nell. "Condition index and chemical composition of meats of Sydney rock oysters (Saccostrea commercialis) and Pacific oysters (Crassostrea gigas) at four sites in Port Stephens, NSW." Marine and Freshwater Research 46, no. 5 (1995): 873. http://dx.doi.org/10.1071/mf9950873.
Full textAbstract:
Adult Sydney rock oysters (Saccostrea commercialis) and Pacific oysters (Crassostrea gigas) were kept on commercial oyster leases at three intertidal sites in Port Stephens, New South Wales, and subtidally under an experimental raft at a fourth site between July 1988 and September 1989. Oysters were sampled from each site at approximately monthly intervals for chemical and histological analysis. Condition index and percentage glycogen of Pacific oysters were higher than those of Sydney rock oysters during winter and spring but tended to be lower during summer and autumn. Gonads of Pacific oysters matured two months earlier than those of Sydney rock oysters, with spawning being observed at all sites in October. Sydney rock oysters spawned later during December-January and did not lose as much condition after spawning as Pacific oysters. The absolute amount of glycogen in the meats of both species dropped at the expense of protein and lipid as the oysters became fully ripe. For both species, general condition of the oysters was best when they were grown subtidally under the raft, although both species were badly affected by invasion of the protistan parasite Mikrocytos roughleyi at this site. Poorest overall condition for both species occurred at a site (Karuah River) that experienced decreased salinities and increased turbidity after rain. Highest condition indices were found in Sydney rock oysters, at the site most dominated by coastal conditions (Corrie Island).
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SU, LAIJIN, LIPING MA, HUI LIU, FENG ZHAO, ZHIWEI SU, and DEQING ZHOU. "Presence and Distribution of Histo-Blood Group Antigens in Pacific Oysters and the Effects of Exposure to Noroviruses GI.3 and GII.4 on Their Expression." Journal of Food Protection 81, no. 11 (October 4, 2018): 1783–90. http://dx.doi.org/10.4315/0362-028x.jfp-18-074.
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ABSTRACT Noroviruses (NoVs) are one of the most important foodborne viral pathogens worldwide. Oysters are common carriers of NoVs and are responsible for their transmission. NoVs recognize human histo-blood group antigens (HBGAs) as receptors. Recent studies indicate that HBGA-like molecules also exist in oyster tissues and that they may play a key role in the binding of NoVs. However, the mechanism by which different genotypes of NoV accumulate in different oyster tissues is unknown. In this study, the presence and distribution of different types of HBGA-like molecules were evaluated in 240 oysters collected from the Shandong Peninsula of People's Republic of China for 1 year. The HBGA-like molecules were detected at various rates and expressed at different levels in different tissues. Immunohistochemistry confirmed the diversity of HBGA-like molecules in four oyster tissues. Eight types of HBGA-like molecules (types A, B, H1, Lewis x, Lewis y, Lewis a, Lewis b, and precursor) were assessed in different tissues. Of these, the type A HBGA-like molecule was consistently expressed in the gills, digestive tissue, and mantle, while types H1 and Lewis b HBGA-like molecules were expressed in the digestive tissues. The expression of HBGA-like molecules in response to the NoV challenge was investigated. The levels of types A, H1, and Lewis x increased significantly in specific oyster tissues after exposure to genogroup II, genotype 4 (GII.4) or genogroup I, genotype 3 (GI.3) NoV. The real-time reverse transcription PCR assays indicated that GI.3 NoV mainly accumulated in the digestive tissues of oysters, whereas GII.4 NoV accumulated in the gills, mantle, and digestive tissues. These results provide new insights into the mechanism of NoV bioaccumulation in oysters and suggest that NoV accumulation in oysters may be related to the expression of HBGA-like molecules.
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Bishop, Melanie J., Fredrick R. Krassoi, Ross G. McPherson, Kenneth R. Brown, Stephen A. Summerhayes, Emma M. Wilkie, and Wayne A. O'Connor. "Change in wild-oyster assemblages of Port Stephens, NSW, Australia, since commencement of non-native Pacific oyster (Crassostrea gigas) aquaculture." Marine and Freshwater Research 61, no. 6 (2010): 714. http://dx.doi.org/10.1071/mf09177.
Full textAbstract:
Proliferation of species introduced for aquaculture can threaten the ecological and economic integrity of ecosystems. We assessed whether the non-native Pacific oyster, Crassostrea gigas, has proliferated, spread and overgrown native Sydney rock oysters, Saccostrea glomerata, in Port Stephens, New South Wales (NSW), Australia, following the 1991 decision to permit its aquaculture within this estuary. Sampling of seven rocky-shore and four mangrove sites immediately before (1990), immediately after (1991–1992) and nearly two decades after (2008) the commencement of C. gigas aquaculture did not support the hypotheses of C. gigas proliferation, spread or overgrowth of S. glomerata. The non-native oyster, uncommon immediately before the commencement of aquaculture, remained confined to the inner port and its percentage contribution to oyster assemblages generally declined over the two decades. C. gigas populations were dominated by individuals of <40-mm shell height, with established adults being rare. Only at one site was there an increase in C. gigas abundance that was accompanied by S. glomerata decline. The failure of C. gigas in Port Stephens to cause the catastrophic changes in fouling assemblages seen elsewhere in the world is likely to reflect estuarine circulation patterns that restrict larval transport and susceptibility of the oysters to native predators.
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Kovalyova, M. A., and O. Yu Vyalova. "The first record of rock-boring mollusc Petricola lithophaga (Retzius, 1788) inside the valves of oysters Crassostrea gigas (Thunberg, 1793), cultivated in Crimea (the Donuzlav Bay, the Black Sea)." Marine Biological Journal 6, no. 1 (March 23, 2021): 34–40. http://dx.doi.org/10.21072/mbj.2021.06.1.03.
Full textAbstract:
The number of mollusc farms off the coast of Crimea and the Caucasus has increased significantly in recent years. The cultivation of the Pacific oyster Crassostrea gigas (Thunberg, 1793) requires monitoring of mollusc health and parasitological control of mariculture farms. The aim of this work was to study species composition of epibionts and endobionts, associated with shells of cultivated oyster C. gigas, as well as to identify species, damaging shells. Commercial oysters with visual shell damage were collected on a mariculture farm in the Donuzlav Bay (Crimea, the Black Sea) and brought to the laboratory alive chilled. As a result of 22 oysters’ examination, 14 macrozoobenthos species and live specimens of rock-boring mollusc Petricola lithophaga (Retzius, 1788) were found. The size of rock-borers varied 9 to 16 mm; their age was about two years. Prolonged presence of P. lithophaga inside oyster valves can cause degradation of shell calcareous layer and even death of the mollusc host; this fact is of great importance for the Black Sea mariculture. Considering P. lithophaga annual development cycle, during the period of mass larval settlement (July to October), it is recommended to inspect the shells of cultivated oysters. Further detailed studies will allow to develop measures for prevention and protection of bivalve molluscs from infestation with P. lithophaga.
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Wilkie, Emma M., and Melanie J. Bishop. "Differences in shell strength of native and non-native oysters do not extend to size classes that are susceptible to a generalist predator." Marine and Freshwater Research 63, no. 12 (2012): 1201. http://dx.doi.org/10.1071/mf12078.
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Whether non-native species proliferate to pest status can depend on top-down control from native predators. Among epifaunal molluscs, the shell serves as a main line of anti-predator defence and shell strength may determine the ease with which generalist predators can penetrate prey. We assessed whether, in eastern Australia, the faster growth of the non-native Pacific oyster, Crassostrea gigas, than that of the native Saccostrea glomerata comes at the cost of reduced investment in shell thickening, rendering the non-native oyster more susceptible to a generalist predator, the muricid gastropod Morula marginalba. Laboratory tests confirmed that among larger (>50-mm shell height) oysters, the shells of C. gigas were weaker than those of similar-sized S. glomerata. There were, however, no differences in shell strength or thickness between smaller S. glomerata and C. gigas of the size consumed by M. marginalba. In the absence of shell-strength differences among smaller oysters, M. marginalba preferentially consumed native over non-native oysters. When, however, M. marginalba had no choice of prey item, C. gigas was consumed at the same rate as the native oyster. Our results add to growing evidence that the invasion of C. gigas in eastern Australian estuaries is, at present, causing minimal disruption to trophic relationships.
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Humphrey, T. J., and K. Martin. "Bacteriophage as models for virus removal from Pacific oysters (Crassostrea gigas) during re-laying." Epidemiology and Infection 111, no. 2 (October 1993): 325–35. http://dx.doi.org/10.1017/s0950268800057034.
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SummaryA study was undertaken to examine the feasibility of using naturally-occurring bacteriophages to assess the impact of re-laying on levels of viral contamination inCrassostrea gigas, the Pacific oyster. Two phages were chosen. One, male-specific (F+), was enumerated usingSalmonella typhimurium. The other, a somatic phage, was detected using an, as yet, uncharacterizedEscherichia coli. Investigations, using a variety of re-laying sites, demonstrated that numbers of F+ phage in oyster tissue declined more rapidly than those of somatic phage. For example, in oysters placed in commercially-used sea water ponds, F+ phage reached undetectable levels within 2–3 weeks, whereas somatic phage could still be detected 5 weeks after re-laying. The studies suggest that F+ phage may not be a suitable indicator for virus removal and that somatic phage may be better suited to this role.
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Crandall, Grace, Rhonda Elliott Thompson, Benoit Eudeline, Brent Vadopalas, Emma Timmins-Schiffman, and Steven Roberts. "Proteomic response of early juvenile Pacific oysters (Crassostrea gigas) to temperature." PeerJ 10 (October 14, 2022): e14158. http://dx.doi.org/10.7717/peerj.14158.
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Pacific oysters (Crassostrea gigas) are a valuable aquaculture product that provides important ecosystem benefits. Among other threats, climate-driven changes in ocean temperature can impact oyster metabolism, survivorship, and immune function. We investigated how elevated temperature impacts larval oysters during settlement (19–33 days post-fertilization), using shotgun proteomics with data-independent acquisition to identify proteins present in the oysters after 2 weeks of exposure to 23 °C or 29 °C. Oysters maintained at elevated temperatures were larger and had a higher settlement rate, with 86% surviving to the end of the experiment; these oysters also had higher abundance trends of proteins related to metabolism and growth. Oysters held at 23 °C were smaller, had a decreased settlement rate, displayed 100% mortality, and had elevated abundance trends of proteins related to immune response. This novel use of proteomics was able to capture characteristic shifts in protein abundance that hint at important differences in the phenotypic response of Pacific oysters to temperature regimes. Additionally, this work has produced a robust proteomic product that will be the basis for future research on bivalve developmental processes.
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Bouilly, Karine, Alexandra Leitão, Raquel Chaves, Henrique Guedes-Pinto, Pierre Boudry, and Sylvie Lapègue. "Endonuclease banding reveals that atrazine-induced aneuploidy resembles spontaneous chromosome loss in Crassostrea gigas." Genome 48, no. 1 (February 1, 2005): 177–80. http://dx.doi.org/10.1139/g04-087.
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Aneuploidy has previously been observed in the Pacific oyster, Crassostrea gigas, and shown to be negatively correlated with growth. Moreover, a significant impact of atrazine exposure has been described in C. gigas, and persistence of that effect has been observed between generations. Evidence of differential chromosome loss has been demonstrated in aneuploid karyotypes of C. gigas using the G-banding technique. Pairs 1, 5, 9, and 10 are characterized by the loss of 1 chromosome. As restriction enzyme (RE) digestion chromosome banding allows a better identification of chromosome pairs, we used this technique to identify which chromosomes are affected when aneuploidy is increased by exposure to atrazine. The progeny of oysters contaminated by atrazine were analysed using the restriction enzyme HaeIII. The study of 26 RE-banded aneuploid karyotypes showed that the same chromosome pairs (1, 5, 9, and 10) were affected by the loss of 1 chromosome (61%, 15%, 42%, and 42%, respectively). Further investigation is required to enable a better understanding of aneuploidy in oysters, especially with respect to why some chromosomes are more easily lost than others, and why cells tolerate the loss of these chromosomes.Key words: aneuploidy, atrazine, restriction enzyme digestion chromosome banding, Pacific oyster, Crassostrea gigas.
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Suquet, Marc, Goulwen de Kermoysan, Ricardo Gonzalez Araya, Isabelle Queau, Luc Lebrun, Pierrick Le Souchu, and Christian Mingant. "Anesthesia in Pacific oyster,Crassostrea gigas." Aquatic Living Resources 22, no. 1 (January 2009): 29–34. http://dx.doi.org/10.1051/alr/2009006.
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LYNCH, S. A., E. ABOLLO, A. RAMILO, A. CAO, S. C. CULLOTY, and A. VILLALBA. "Observations raise the question if the Pacific oyster, Crassostrea gigas, can act as either a carrier or a reservoir for Bonamia ostreae or Bonamia exitiosa." Parasitology 137, no. 10 (April 14, 2010): 1515–26. http://dx.doi.org/10.1017/s0031182010000326.
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SUMMARYThis study investigated the ability of the Pacific oyster, Crassostrea gigas, to act as a carrier or reservoir of the protistan Bonamia ostreae. Studies were carried out independently in Ireland and in Spain. Naïve C. gigas were exposed to B. ostreae both in the field and in the laboratory via natural exposure or experimental injection. Naïve flat oysters, Ostrea edulis, were placed in tanks with previously exposed C. gigas. Oysters were screened for B. ostreae by examination of ventricular heart smears and by polymerase chain reaction (PCR) screening of tissue samples (gill and/or heart) and shell cavity fluid. PCR-positive oysters were further screened using histology and in situ hybridization (ISH). B. ostreae DNA was detected in the tissues and/or shell cavity fluid of a small number of C. gigas in the field and in the laboratory. B. ostreae-like cells were visualized in the haemocytes of 1 C. gigas and B. ostreae-like cells were observed extracellularly in the connective tissues of 1 other C. gigas. When C. gigas naturally exposed to B. ostreae were held with naïve O. edulis, B. ostreae DNA was detected in O. edulis; however, B. ostreae cells were not visualized. In Spain, B. exitiosa DNA was also detected in Pacific oyster tissues. The results of this study have important implications for C. gigas transfers from B. ostreae-endemic areas to uninfected areas and highlight B. ostreae and B. exitiosa's ability to survive extracellularly and in other non-typical hosts.
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Rodrigues, Inês C., Nânci Santos-Ferreira, Daniela Silva, Carla Chiquelho da Silva, Ângela S. Inácio, Maria São José Nascimento, and Paulo Martins da Costa. "A One-Year Systematic Study to Assess the Microbiological Profile in Oysters from a Commercial Harvesting Area in Portugal." Microorganisms 11, no. 2 (January 29, 2023): 338. http://dx.doi.org/10.3390/microorganisms11020338.
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As filter-feeding animals farmed in water bodies exposed to anthropogenic influences, oysters can be both useful bioremediators and high-risk foodstuffs, considering that they are typically consumed raw. Understanding the dynamic of bacterial and viral load in Pacific oyster (Crassostrea gigas) tissues, hemolymph, outer shell surface biofilm, and farming water is therefore of great importance for microbiological risk assessment. A one-year survey of oysters collected from a class B production area (Canal de Mira, on the Portuguese western coast) revealed that these bivalve mollusks have a good depurating capacity with regard to bacteria, as Salmonella spp. and viable enterococci were not detected in any oyster flesh (edible portion) samples, despite the fact that these bacteria have regularly been found in the farming waters. Furthermore, the level of Escherichia coli contamination was clearly below the legal limit in oysters reared in a class B area (>230–≤4600 MPN E. coli/100 g). On the contrary, norovirus was repeatedly detected in the digestive glands of oysters sampled in autumn, winter, and spring. However, their presence in farming waters was only detected during winter.
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Hwang, Dukhyun, Min-jae Kang, Mi Jo, Yong Seo, Nam Park, and Gun-Do Kim. "Anti-Inflammatory Activity of β-thymosin Peptide Derived from Pacific Oyster (Crassostrea gigas) on NO and PGE2 Production by Down-Regulating NF-κB in LPS-Induced RAW264.7 Macrophage Cells." Marine Drugs 17, no. 2 (February 21, 2019): 129. http://dx.doi.org/10.3390/md17020129.
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β-thymosin is known for having 43 amino acids, being water-soluble, having a light molecular weight and ubiquitous polypeptide. The biological activities of β-thymosin are diverse and include the promotion of wound healing, reduction of inflammation, differentiation of T cells and inhibition of apoptosis. Our previous studies showed that oyster β-thymosin originated from the mantle of the Pacific oyster, Crassostrea gigas and had antimicrobial activity. In this study, we investigated the anti-inflammatory effects of oyster β-thymosin in lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells using human β-thymosin as a control. Oyster β-thymosin inhibited the nitric oxide (NO) production as much as human β-thymosin in LPS-induced RAW264.7 cells. It also showed that oyster β-thymosin suppressed the expression of prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, oyster β-thymosin reduced inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Oyster β-thymosin also suppressed the nuclear translocation of phosphorylated nuclear factor-κB (NF-κB) and degradation of inhibitory κB (IκB) in LPS-induced RAW264.7 cells. These results suggest that oyster β-thymosin, which is derived from the mantle of the Pacific oyster, has as much anti-inflammatory effects as human β-thymosin. Additionally, oyster β-thymosin suppressed NO production, PGE2 production and inflammatory cytokines expression via NF-κB in LPS-induced RAW264.7 cells.
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Banker, Roxanne M. W., Jacob Lipovac, John J. Stachowicz, and David A. Gold. "Sodium molybdate does not inhibit sulfate-reducing bacteria but increases shell growth in the Pacific oyster Magallana gigas." PLOS ONE 17, no. 2 (February 9, 2022): e0262939. http://dx.doi.org/10.1371/journal.pone.0262939.
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Recent work on microbe-host interactions has revealed an important nexus between the environment, microbiome, and host fitness. Marine invertebrates that build carbonate skeletons are of particular interest in this regard because of predicted effects of ocean acidification on calcified organisms, and the potential of microbes to buffer these impacts. Here we investigate the role of sulfate-reducing bacteria, a group well known to affect carbonate chemistry, in Pacific oyster (Magallana gigas) shell formation. We reared oyster larvae to 51 days post fertilization and exposed organisms to control and sodium molybdate conditions, the latter of which is thought to inhibit bacterial sulfate reduction. Contrary to expectations, we found that sodium molybdate did not uniformly inhibit sulfate-reducing bacteria in oysters, and oysters exposed to molybdate grew larger shells over the experimental period. Additionally, we show that microbiome composition, host gene expression, and shell size were distinct between treatments earlier in ontogeny, but became more similar by the end of the experiment. Although additional testing is required to fully elucidate the mechanisms, our work provides preliminary evidence that M. gigas is capable of regulating microbiome dysbiosis caused by environmental perturbations, which is reflected in shell development.
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Launey, Sophie, and Dennis Hedgecock. "High Genetic Load in the Pacific Oyster Crassostrea gigas." Genetics 159, no. 1 (September 1, 2001): 255–65. http://dx.doi.org/10.1093/genetics/159.1.255.
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Abstract The causes of inbreeding depression and the converse phenomenon of heterosis or hybrid vigor remain poorly understood despite their scientific and agricultural importance. In bivalve molluscs, related phenomena, marker-associated heterosis and distortion of marker segregation ratios, have been widely reported over the past 25 years. A large load of deleterious recessive mutations could explain both phenomena, according to the dominance hypothesis of heterosis. Using inbred lines derived from a natural population of Pacific oysters and classical crossbreeding experiments, we compare the segregation ratios of microsatellite DNA markers at 6 hr and 2–3 months postfertilization in F2 or F3 hybrid families. We find evidence for strong and widespread selection against identical-by-descent marker homozygotes. The marker segregation data, when fit to models of selection against linked deleterious recessive mutations and extrapolated to the whole genome, suggest that the wild founders of inbred lines carried a minimum of 8–14 highly deleterious recessive mutations. This evidence for a high genetic load strongly supports the dominance theory of heterosis and inbreeding depression and establishes the oyster as an animal model for understanding the genetic and physiological causes of these economically important phenomena.
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EZGETA BALIĆ, DARIA, IVANA RADONIĆ, DUBRAVKA BOJANIĆ VAREZIĆ, BARBARA ZORICA, JASNA ARAPOV, NIKA STAGLIČIĆ, SLAVEN JOZIĆ, et al. "Reproductive cycle of a non-native oyster, Crassostrea gigas, in the Adriatic Sea." Mediterranean Marine Science 21, no. 1 (April 27, 2020): 146. http://dx.doi.org/10.12681/mms.21304.
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The Pacific oyster Crassostrea gigas was introduced for the aquaculture purposes in many different parts of the world. However, the species has never been officially introduced for commercial farming in the Croatian part of the Adriatic Sea. Interestingly, in the 1970s, the Pacific oyster has been reported in the natural habitats of the Lim Bay, in northern Adriatic Sea. Although the species was recorded there, there is a lack of knowledge about its biology and ecology in this region, including a reproductive cycle. Information on the reproductive biology of non-indigenous species in new areas is crucial for prediction of their future survival and possible spread in invaded habitats. In this study, we provide the first data on the reproductive biology of the Pacific oyster in the Adriatic Sea, the northernmost part of the Mediterranean Sea. Quantitative and qualitative methods of gonad tissue analysis were conducted, and effects of environmental conditions on the gametogenesis were evaluated during two reproductive cycles. Our study confirmed that environmental conditions in the Lim Bay were favourable for the reproduction of the species. The Pacific oyster reproduced once per year and had a prolonged spawning period. Water temperature was the main factor affecting gonad development and oocyte size, while chlorophyll a concentration had an impact on the oocyte development in terms of their size.
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Tsai, Hsin-Shan, Yu-Tien Hsiao, and Yih-Ming Weng. "Effects of Individual and Block Freezing on the Quality of Pacific Oyster (Crassostrea gigas) during Storage under Different Pretreatment Conditions." Sustainability 14, no. 15 (August 1, 2022): 9404. http://dx.doi.org/10.3390/su14159404.
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In this study, a series of pretreatments, including ice-glazing, polyphosphate impregnated, and both ice-glazing and polyphosphate impregnated, were employed to pretreat shucked oysters in order to explore the optimal processing conditions for long-time storage. The effect of repeated freezing-thawing cycles on the quality of oysters was evaluated. Several quality indicators were used to investigate the effects of pretreatment. For the VBN (volatile salt-based nitrogen) value, the lowest value was 9.1 ± 0.2 of BPG (block oyster with polyphosphate impregnated and ice-glazing), which was significantly lower than 9.6 ± 0.2 of IPG (individual oyster with polyphosphate impregnated and ice-glazing). In terms of drip loss, there was no significant difference between the IPG (21.0 ± 0.2%) and the BPG (20.8 ± 0.2%). In addition, the highest WHC% (water holding capacity) was IPG (65.5 ± 0.5%) which was slightly lower than BPG (67.6 ± 0.6%). As compared to the experimental control, the IPG and BPG had the best appearance and color. In terms of TAPC (total aerobic plate count), with the increase of freezing storage time, each group showed a slight downward trend, but the difference was not statistically significant. After repeated freezing-thawing of block frozen oysters, there were significant differences in drip loss, WHC, and cooked taste with the increasing number of times, and there was a trend of deterioration (p < 0.05). Repeated freezing and thawing can seriously degrade the quality of oysters, so individual freezing (especially IPG) should be the most appropriate processing method.
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Fu, Huiru, Zexin Jiao, Yongjing Li, Jing Tian, Liting Ren, Fuqiang Zhang, Qi Li, and Shikai Liu. "Transient Receptor Potential (TRP) Channels in the Pacific Oyster (Crassostrea gigas): Genome-Wide Identification and Expression Profiling after Heat Stress between C. gigas and C. angulata." International Journal of Molecular Sciences 22, no. 6 (March 22, 2021): 3222. http://dx.doi.org/10.3390/ijms22063222.
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Transmembrane proteins are involved in an array of stress responses, particularly in thermo-sensation and thermo-regulation. In this study, we performed a genome-wide identification and characterization of the Transient Receptor Potential (TRP) genes in the Pacific oyster (Crassostrea gigas) and investigated their expression profiles after heat stress to identify critical TRPs potentially associated with thermal regulation. A total of 66 TRP genes were identified in the C. gigas, which showed significant gene expansion and tandem duplication. Meta-analysis of the available RNA-Seq data generated from samples after acute heat stress revealed a set of heat-inducible TRPs. Further examination of their expression profiles under chronic heat stress, and comparison between C. gigas and C. angulata, two oyster species with different tolerance levels to heat stress, led to the identification of TRPC3.6, TRPC3.7, and TRPV4.7 as important TRPs involved in thermal regulation in oysters. This work provided valuable information for future studies on the molecular mechanism of TRP mediated thermal tolerance, and identification of diagnostic biomarker for thermal stress in the oysters.
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Gray, Matthew W., and Chris J. Langdon. "Ecophysiology of the Olympia Oyster, Ostrea lurida, and Pacific Oyster, Crassostrea gigas." Estuaries and Coasts 41, no. 2 (June 26, 2017): 521–35. http://dx.doi.org/10.1007/s12237-017-0273-7.
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