Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically im...Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically important aquaculture species,and its productive traits can be improved by hybridization.Here,an intraspecific cross between orange shell(O,10th generation)and‘Haida No.1’(H,13th generation)of C.gigas was performed to assess the heterosis of survival trait.Survival rates of hybrid family(OH)and inbred families(HH and OO)were compared at larval stage,and eyed-pediveliger larvae of three families were subjected to transcriptome analysis.The analysis results of best-parent heterosis and mid-parent heterosis showed that the hybrid family exhi-bited a high heterosis in survival relative to the parental families.The OH-M(OH vs.OO)and OH-P(OH vs.HH)had 425 and 512 dif-ferentially expressed genes(DEGs),respectively.Functional enrichment analysis of these DEGs revealed that the significantly enrich-ed genes function in virion binding,C-type lectin receptor signaling pathway,cellular defense response and other immune-related pro-cesses,which involves perlucin-like protein,CD209 antigen-like protein,ZNFX1,caspase-3 and acan genes.These differentially ex-pressed genes in OH-M and OH-P,together with the immune-related processes mentioned above may play an important role in the larval survival of C.gigas.In addition,three genes(CYP450,fucolectin and perlucin-like)are associated with the orange shell and low survival of maternal oyster OO.These findings provide support for the application of hybrid with superior survival and will facilitate the understanding of heterosis formation in the Pacific oyster.展开更多
Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments.Its growth and burial process is a carbon sequestration and storage process.Oyster shell may stop growing due to suffer from fre...Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments.Its growth and burial process is a carbon sequestration and storage process.Oyster shell may stop growing due to suffer from freeze shock during the winter season within a temperate climate,therefore,in order to study the carbon sequestration capacity of oysters we need to know the water temperature at which the shell suffer from winter freeze shock.This study examinesδ^(18)O profiles across consecutive micro-growth layers found in three modern Pacific oyster shells from the northwest coast of Bohai Bay.A total of 165 oxygen isotope values from sequential samples of their left shells showed periodically varying values,and the variation fluctuation of oxygen isotope values was 4.97‰on average.According to the variation range of the oxygen isotope value of the shell,combined with the sea surface temperature and the sea surface salinity data of the water in which the oysters grew,the water temperature that suffer from winter freeze shock and stops or retards the growth of Pacific oysters in Bohai Bay is about 8.3℃,and the corresponding period is from December to March of the following year.The calcification time of oysters within one year is nearly a month longer than previously thought,therefore,its carbon sink potential is also improved.展开更多
Microsatellite DNA technique was used to detect the genetic variation between five hatchery populations of the Pacific oyster from China and two wild populations from Japan. Seven microsatellite loci screened in this ...Microsatellite DNA technique was used to detect the genetic variation between five hatchery populations of the Pacific oyster from China and two wild populations from Japan. Seven microsatellite loci screened in this study showed high polymorphism in both hatchery and wild populations, as observed in an average number of allele per locus （19.1-29.9） and average expected heterozygosity （0.916-0.958）. No significant difference in average allelic richness or expected heterozygosity was observed between Chinese hatchery populations and Japanese wild populations. Pairwise Fsr values and heterogeneity tests of allele frequencies showed significant genetic differentiation between all populations. According to the neighbor-joining tree constructed on the basis of the Dc distance, the seven populations fell into three groups showing a clear division between hatchery and wild populations, and between the northern and southern hatchery populations. Assignment tests correctry assigned high percentages （97%-100%） of individuals to their original populations and demonstrated the feasibility of microsatellite analysis for discrimination between populations. The information obtained in this study is useful for designing suitable management guidelines and selective breeding programs for the Pacific oyster in China.展开更多
To evaluate the combined effect of temperature and cadmium on the molecular responses of heat shock protein 70(hsp70)and P-glycoprotein(P-gp)in mantle,digestive gland and gills of Crassostrea gigas,oysters were expose...To evaluate the combined effect of temperature and cadmium on the molecular responses of heat shock protein 70(hsp70)and P-glycoprotein(P-gp)in mantle,digestive gland and gills of Crassostrea gigas,oysters were exposed to combinations of five temperature levels(10,15,20,25,and 30℃)and 10μg L^(-1)cadmium for 21 days.Oysters were sampled for mRNA quantification by qPCR,and the results showed that the P-gp gene expression changed significantly after treatment at different temperatures and different treatment times.The P-gp gene expression was the highest in the digestive gland.Compared with the control group,the P-gp gene expression in cadmium treatment groups at all the different temperatures were significantly higher than the control group.The control oysters(kept at 10℃during the whole experiment without cadmium)expressed low levels of hsp70,but the groups treated with cadmium displayed somewhat higher levels.The present study demonstrated hsp70 and P-gp played an important role in the detoxification of Cd in C.gigas,and confirmed temperature should be considered for the assessment of Cd-induced toxicity in oysters.展开更多
Carotenoids play crucial physiological roles in animals.A comprehensive investigation into the mechanism of carotenoid metabolism in oysters will establish a theoretical foundation for further development of its carot...Carotenoids play crucial physiological roles in animals.A comprehensive investigation into the mechanism of carotenoid metabolism in oysters will establish a theoretical foundation for further development of its carotenoid-rich traits.However,the information on the function of miRNA in β-carotene metabolism in oysters is limited.To elucidate the mechanisms underlying miRNA regulation of carotenoid metabolism in oysters,we compared the expressions of miRNA in digestive gland tissues of Pacific oyster(Crassostrea gigas)fed with aβ-carotene supplemented diet and a normal diet,respectively.A total of 690 candidate miRNAs in the Pacific oyster digestive gland tissues were identified,including 590 known miRNAs and 111 unknown miRNAs.Three differentially expressed miRNAs were obtained in the carotenoid-fed and normal groups,associated to 137 differentially expressed target genes.Moreover,the GO enrichment analysis revealed that the differentially expressed target genes were mainly involved in transmembrane transport activity.KEGG enrichment showed that the differentially expressed target genes were involved in ABC transport.Analysis of the mRNA-miRNA network revealed that novel0025 played a central role in carotenoid metabolism,and it was negatively correlated with the expression of 46 mRNAs.In addition,down-regulated expression of novel0025 upregulated the expression of the lipoprotein gene LOC105342186,suggesting a potential regulatory role in carotenoid metabolism.Our results provide useful information for elucidating the miRNA regulation mechanism during carotenoids metabolism in the Pacific oyster.展开更多
There is an increasing requirement for traceability of aquaculture products, both for consumer protection and for food safety. There are high error rates in the conventional traceability systems depending on physical ...There is an increasing requirement for traceability of aquaculture products, both for consumer protection and for food safety. There are high error rates in the conventional traceability systems depending on physical labels. Genetic traceability technique depending on DNA-based tracking system can overcome this problem. Genealogy information is essential for genetic traceability, and microsatellite DNA marker is a good choice for pedigree analysis. As increasing genotyping throughput of microsatellites, microsatellite multiplex PCR has become a fast and cost-effective technique. As a commercially important cultured aquatic species, Pacific oyster Crassostrea gigas has the highest global production. The objective of this study was to develop microsatellite multiplex PCR panels with dye-labeled universal primer for pedigree analysis in C. gigas, and these multiplex PCRs were validated using 12 full-sib families with known pedigrees. Here we developed six informative multiplex PCRs using 18 genomic microsatellites in C. gigas. Each multiplex panel contained a single universal primer M13(-21) used as a tail on each locus-specific forward primer and a single universal primer M13(-21) labeled with fluorophores. The polymorphisms of the markers were moderate, with an average of 10.3 alleles per locus and average polymorphic information content of 0.740. The observed heterozygosity per locus ranged from 0.492 to 0.822. Cervus simulations revealed that the six panels would still be of great value when massive families were analysed. Pedigree analysis of real offspring demonstrated that 100% of the offspring were unambiguously allocated to their parents when two multiplex PCRs were used. The six sets of multiplex PCRs can be an important tool for tracing cultured individuals, population genetic analysis, and selective breeding program in C. gigas.展开更多
The shell color of Pacific oyster(Crassostrea gigas) is a desirable trait; but the nutritional studies on C. gigas with different shell colors have not been conducted. Through successive selective breeding, five shell...The shell color of Pacific oyster(Crassostrea gigas) is a desirable trait; but the nutritional studies on C. gigas with different shell colors have not been conducted. Through successive selective breeding, five shell color strains of black(B), purple(P), orange(O), golden(G) and white(W) C. gigas have been developed. The aim of this study was to evaluate the chemical composition and nutritional value of five shell color strains and one commercial population with a common color. The biochemical composition including moisture, total protein, glycogen, ash, total fat, fatty acids(FA), amino acids and minerals was detected. The results indicated that the protein(50.76%–56.57%) was the major component. The content of glycogen showed a significant difference between orange shell and golden shell strains, as well as between commercial population and golden shell strain. In addition, all shell color strains contained a large amount of essential amino acids(12.20–14.15 g(100 g)^(-1)), of them leucine(2.81–3.29 g(100 g)^(-1)) and lysine(2.79–3.28 g(100 g)^(-1)) were predominant. The oysters were rich in polyunsaturated fatty acids(42.26%–45.24% of total fatty acid) with high levels of DHA(18.53%–21.16% of total fatty acid) and EPA(17.23%–18.68% of total fatty acid). Significant differences of mineral contents(Mg, Zn, Fe and Cu) were identified among the six populations. These results indicated that C. gigas with different shell colors presented rich nutritional value with high protein, glycogen, essential amino acids and polyunsaturated fatty acids. The biochemical composition obtained in this study is useful for selective breeding of C. gigas with different shell colors.展开更多
Glycogen is important not only for the energy supplementary of oysters, but also for human consumption. High glycogen content can improve the stress survival of oyster. A key enzyme in glycogenesis is glycogen synthas...Glycogen is important not only for the energy supplementary of oysters, but also for human consumption. High glycogen content can improve the stress survival of oyster. A key enzyme in glycogenesis is glycogen synthase that is encoded by glycogen synthase gene GYS. In this study, the relationship between single nucleotide polymorphisms(SNPs) in coding regions of Crassostrea gigas GYS(Cg-GYS) and individual glycogen content was investigated with 321 individuals from five full-sib families. Single-strand conformation polymorphism(SSCP) procedure was combined with sequencing to confirm individual SNP genotypes of Cg-GYS. Least-square analysis of variance was performed to assess the relationship of variation in glycogen content of C. gigas with single SNP genotype and SNP haplotype. As a consequence, six SNPs were found in coding regions to be significantly associated with glycogen content(P < 0.01), from which we constructed four main haplotypes due to linkage disequilibrium. Furthermore, the most effective haplotype H2(GAGGAT) had extremely significant relationship with high glycogen content(P < 0.0001). These findings revealed the potential influence of Cg-GYS polymorphism on the glycogen content and provided molecular biological information for the selective breeding of good quality traits of C. gigas.展开更多
The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a s...The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas.展开更多
Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were det...Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were detected in 46.7% of loci, accounting for 11.7% of the total alleles. Four loci did not segregate in Mendelian Ratios. Three linkage groups were identified among 7 of the 15 segregating loci. Fluorescence-based automated capillary electrophoresis (ABI 310 Genetic Analyzer) that used to detect the microsatellite loci, has been proved a fast, precise, and reliable method in microsatellite genotyping.展开更多
Mass selection for fast growth was conducted in three Pacific oyster (Crassostrea gigas) stocks from China, Japan and Korea using previously established lines (CS1, JS1, and KS1). To determine whether continuous progr...Mass selection for fast growth was conducted in three Pacific oyster (Crassostrea gigas) stocks from China, Japan and Korea using previously established lines (CS1, JS1, and KS1). To determine whether continuous progress can be achieved by selection for growth, the progeny of three second-generation Pacific oyster lines was selected for shell height and evaluated via a 400-day farming experiment. When harvested at the end of the experiment, the selected crosses of CS2, JS2, and KS2 lines grew by 9.2%, 10.2% and 9.6% larger than the control crosses, respectively. During grow-out stage, the genetic gain of three selected lines was (10.2 ± 1.4)%, (10.4 ± 0.3)%, and (8.4 ± 1.6)%, respectively; and the corresponding realized heritability was 0.457 ± 0.143, 0.312 ± 0.071 and 0.332 ± 0.009, respectively. These results indicated that the selection for fast growth achieved steady progress in the second generation of oyster. Our work provides supportive evidence for the continuity of the Pacific oyster selective breeding program.展开更多
Five full-sib families of the Pacific oyster(Crassostrea gigas) larvae were used to study the mode of inheritance at eight microsatellite loci,and the feasibility of these markers for kinship estimate was also examine...Five full-sib families of the Pacific oyster(Crassostrea gigas) larvae were used to study the mode of inheritance at eight microsatellite loci,and the feasibility of these markers for kinship estimate was also examined.All eight microsatellite loci were compatible with Mendelian inheritance.Neither evidence of sex-linked barriers to transmission nor evidence of major barriers to fertilization between gametes from the parents was shown.Three of the eight loci showed the presence of null alleles in four families,demonstrating the need to conduct comprehensive species-specific inheritance studies for microsatellite loci used in population genetic studies.Although the null allele heterozygotes were considered as homozygotes in the calculation of genetic distance,offspring from five full-sib families were unambiguously discriminated in the neighbor-joining dendrogram.This result indicates that the microsatellite markers may be capable of discriminating between related and unrelated oyster larvae in the absence of pedigree information,and is applicable to the investigation of the effective number of parents contributing to the hatchery population of the Pacific oyster.展开更多
Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are str...Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population,as well as the experimental design for an association analysis.In this study,we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster(Crassostrea gigas).A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites,respectively.For syntenic marker pairs,no significant association was observed in the wild population;however,three significant associations occurred in the cultured population,and the significant LD extended up to 12.7 c M,indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population.The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population.Furthermore,the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster.The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.展开更多
A variety of shell colors are one of the most fundamental characteristics of molluscs,which have importantly ecological and economic signifi cance.The Pacifi c oyster Crassostrea gigas is distributed in many sea areas...A variety of shell colors are one of the most fundamental characteristics of molluscs,which have importantly ecological and economic signifi cance.The Pacifi c oyster Crassostrea gigas is distributed in many sea areas around the world and also an aquacultured mollusc with high nutritional value.In this study,the whole soft body and the mantle tissue of black-shelled Pacifi c oyster(BSO)and white-shelled Pacifi c oyster(WSO)with starkly diff erent melanin contents were compared,and the diff erences in physiology and metabolism between BSO and WSO were analyzed.The results of physiological indicators suggested BSO show more melanin,more dry matter,more crude lipid content,and stronger ability to scavenge free radicals than WSO.The altered metabolites of glycerophospholipids,fatty acyls,and steroids revealed diff erent regulatory mechanisms of lipids.The correlation analysis of metabolomics and previously published RNAseq data suggested that BSO and WSO mainly diff ered in the basal metabolic processes,such as lipid,amino acid and purine metabolisms.This study provides insights into the changes in the physiological indictors and the metabolites of oysters with varying melanin content.展开更多
Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximatel...Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximately determine the nutrient content of the Pacific oyster Crassostreagigas.Samples of C.gigas from 19 costal sites were freeze-dried,ground,and scanned for spectral data collection using a Fourier transform NIR spectrometer(Thermo Fisher Scientific).NIRS models of glycogen and other nutrients were established using partial least squares,multiplication scattering correction first-order derivation,and Norris smoothing.The R_(C) values of the glycogen,fatty acids,amino acids,and taurine NIRS models were 0.9678,0.9312,0.9132,and 0.8928,respectively,and the residual prediction deviation(RPD)values of these components were 3.15,2.16,3.11,and 1.59,respectively,indicating a high correlation between the predicted and observed values,and that the models can be used in practice.The models were used to evaluate the nutrient compositions of 1278 oyster samples.Glycogen content was found to be positively correlated with fatty acids and negatively correlated with amino acids.The glycogen,amino acid,and taurine levels of C.gigas cultured in the subtidal and intertidal zones were also significantly different.This study suggests that C.gigas NIRS models can be a cost-effective alternative to traditional methods for the rapid and proximate analysis of various slaughter traits and may also contribute to future genetic and breeding-related studies in Pacific oysters.展开更多
The color of Mollusca shells is one of the most important attributes to consumers.At the cellular level,black color is mainly from the melanin produced by melanocytes.The melanosome is a specialized membrane-bound org...The color of Mollusca shells is one of the most important attributes to consumers.At the cellular level,black color is mainly from the melanin produced by melanocytes.The melanosome is a specialized membrane-bound organelle that is involved in melanin synthesis,storage,and transportation.How the complex pigmentation process in the Crassostrea gigas is established remains an open question.The objectives of this studies are to examine the morphological characteristics of melanosomes or melanin of mantle pigmentation in the Pacific oyster,thereby investigating its contribution to shell color.The results show that pigmented granules of the mantles vary among the three lobes,and the melanosomes at different stages are enriched in distinct cargo molecules,which indicate the remarkable difference between the marginal mantle and central mantle.Examination of mantle histology reveals that the mantle margin of the oyster is characterized by three different folds,including the outer secretory,middle sensory,and inner muscular fold.Ferrous ion chelating assays against the tyrosine hydroxylase indicate that a large amount of melanin is localized in the inner surface of the middle fold.Transmission electron microscopy analyses show that the mantle edge is composed of tall columnar and cuboidal epidermal cells and some pigmented melanocytes intersperse among these cells.The numbers of melanosomes among the three lobes are different.In the inner fold and the middle fold of the mantle,some single dispersion,or aggregation of melanosomes with different degrees of melanization are found in the outer surface.Numerous melanosomes are distributed in the epithelium of the outer fold of the mantle,and mainly are at the apical microvillar surface near the lumen.However,melanosomes are occasionally observed in the central mantle,and they are relatively less.This work provides new insights into the process of melanin deposit in the mantle and shell pigmentation in C.gigas.展开更多
Heavy metal pollution can affect the immune capability of organisms. We evaluated the effect of cadmium （Cd） on the defense responses of the Pacific oyster Crassostrea gigas to Listonella anguillarum challenge. The ...Heavy metal pollution can affect the immune capability of organisms. We evaluated the effect of cadmium （Cd） on the defense responses of the Pacific oyster Crassostrea gigas to Listonella anguillarum challenge. The activities of several important defensive enzymes, including superoxide dismutase （SOD）, glutathione peroxidase （GPx）, acid phosphatase （ACP）, Na＋, K＋-ATPase in gills and hepatopancreas, and phenoloxidase-like （POL） enzyme in hemolymph were assayed. In addition, the expression levels of several genes, including heat shock protein 90 （IrtSP9~））, metallothionein （MT）, and bactericidal/permeability increasing （BPI） protein were quantified by fluorescent quantitative PCR. The enzyme activities of SOD, ACP, POL, and GPx in hepatopancreas, and the expression of HSP90 were down-regulated, whereas GPx activity in the gill, Na＋, K＋-ATPase activities in both tissues, and MT expression was increased in Cd- exposed oysters post L. anguillarum challenge. However, BPI expression was not significantly altered by co-stress of L. anguillarum infection and cadmium exposure. Our results suggest that cadmium exposure alters the oysters＇ immune responses and energy metabolism following vibrio infection.展开更多
Polyploid breeding is widely used in various marine species. Low salinity treatment is an effective method of inducing triploid of bivalve mollusks. In this study, RNA-seq was performed to determine genes and pathways...Polyploid breeding is widely used in various marine species. Low salinity treatment is an effective method of inducing triploid of bivalve mollusks. In this study, RNA-seq was performed to determine genes and pathways involved in hyposaline adaption and cell division of Pacific oyster(Crassostrea gigas) zygotes, trying to better understand the possible molecular mechanism of hypo-osmotic induction. A total of 26965 unigenes were generated in the de novo assembly of clean Illumina reads with an average length of 934 bp and N50 of 1721 bp. Of 3024 differentially expressed genes(DEGs), 2501 were up-regulated and 523 were downregulated. GO(Gene Ontology) annotation and KEGG(Kyoto Encyclopedia of Genes and Genomes) pathway analysis of these DEGs revealed that these DEGs participate a variety of biological processes including osmoregulation, cytoskeleton organization, cell survival and death, and substantially modulate cell proliferation and embryonic development. In summery, RNA-seq methodology was applied for the first time to demonstrate hypotonic-induced transcriptomic alteration in oyster zygotes. Our findings not only interpreted the relatively high mortality of induced larvae, but also provided a valuable reference for further investigations on the mechanism of hyposaline induction, thus should aid to the application of low salinity in triploid induction in large scale aquaculture in future.展开更多
基金supported by the grants from the China Agriculture Research System Project(No.CARS-49)the Earmarked Fund for Agriculture Seed Improvement Project of Shandong Province(No.2020LZGC016).
文摘Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically important aquaculture species,and its productive traits can be improved by hybridization.Here,an intraspecific cross between orange shell(O,10th generation)and‘Haida No.1’(H,13th generation)of C.gigas was performed to assess the heterosis of survival trait.Survival rates of hybrid family(OH)and inbred families(HH and OO)were compared at larval stage,and eyed-pediveliger larvae of three families were subjected to transcriptome analysis.The analysis results of best-parent heterosis and mid-parent heterosis showed that the hybrid family exhi-bited a high heterosis in survival relative to the parental families.The OH-M(OH vs.OO)and OH-P(OH vs.HH)had 425 and 512 dif-ferentially expressed genes(DEGs),respectively.Functional enrichment analysis of these DEGs revealed that the significantly enrich-ed genes function in virion binding,C-type lectin receptor signaling pathway,cellular defense response and other immune-related pro-cesses,which involves perlucin-like protein,CD209 antigen-like protein,ZNFX1,caspase-3 and acan genes.These differentially ex-pressed genes in OH-M and OH-P,together with the immune-related processes mentioned above may play an important role in the larval survival of C.gigas.In addition,three genes(CYP450,fucolectin and perlucin-like)are associated with the orange shell and low survival of maternal oyster OO.These findings provide support for the application of hybrid with superior survival and will facilitate the understanding of heterosis formation in the Pacific oyster.
基金financial support from NSFC(Account 41473013,40872106,and 41627802)。
文摘Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments.Its growth and burial process is a carbon sequestration and storage process.Oyster shell may stop growing due to suffer from freeze shock during the winter season within a temperate climate,therefore,in order to study the carbon sequestration capacity of oysters we need to know the water temperature at which the shell suffer from winter freeze shock.This study examinesδ^(18)O profiles across consecutive micro-growth layers found in three modern Pacific oyster shells from the northwest coast of Bohai Bay.A total of 165 oxygen isotope values from sequential samples of their left shells showed periodically varying values,and the variation fluctuation of oxygen isotope values was 4.97‰on average.According to the variation range of the oxygen isotope value of the shell,combined with the sea surface temperature and the sea surface salinity data of the water in which the oysters grew,the water temperature that suffer from winter freeze shock and stops or retards the growth of Pacific oysters in Bohai Bay is about 8.3℃,and the corresponding period is from December to March of the following year.The calcification time of oysters within one year is nearly a month longer than previously thought,therefore,its carbon sink potential is also improved.
基金the Ministry of Education (No. NCET-04-0640)the National Natural Science Foundation of China (No. 30571442).
文摘Microsatellite DNA technique was used to detect the genetic variation between five hatchery populations of the Pacific oyster from China and two wild populations from Japan. Seven microsatellite loci screened in this study showed high polymorphism in both hatchery and wild populations, as observed in an average number of allele per locus （19.1-29.9） and average expected heterozygosity （0.916-0.958）. No significant difference in average allelic richness or expected heterozygosity was observed between Chinese hatchery populations and Japanese wild populations. Pairwise Fsr values and heterogeneity tests of allele frequencies showed significant genetic differentiation between all populations. According to the neighbor-joining tree constructed on the basis of the Dc distance, the seven populations fell into three groups showing a clear division between hatchery and wild populations, and between the northern and southern hatchery populations. Assignment tests correctry assigned high percentages （97%-100%） of individuals to their original populations and demonstrated the feasibility of microsatellite analysis for discrimination between populations. The information obtained in this study is useful for designing suitable management guidelines and selective breeding programs for the Pacific oyster in China.
基金supported by the earmarked fund for the Modern Agroindustry Technology Research System in Shandong Province (No.SDAIT-14)。
文摘To evaluate the combined effect of temperature and cadmium on the molecular responses of heat shock protein 70(hsp70)and P-glycoprotein(P-gp)in mantle,digestive gland and gills of Crassostrea gigas,oysters were exposed to combinations of five temperature levels(10,15,20,25,and 30℃)and 10μg L^(-1)cadmium for 21 days.Oysters were sampled for mRNA quantification by qPCR,and the results showed that the P-gp gene expression changed significantly after treatment at different temperatures and different treatment times.The P-gp gene expression was the highest in the digestive gland.Compared with the control group,the P-gp gene expression in cadmium treatment groups at all the different temperatures were significantly higher than the control group.The control oysters(kept at 10℃during the whole experiment without cadmium)expressed low levels of hsp70,but the groups treated with cadmium displayed somewhat higher levels.The present study demonstrated hsp70 and P-gp played an important role in the detoxification of Cd in C.gigas,and confirmed temperature should be considered for the assessment of Cd-induced toxicity in oysters.
基金supported by grants from the Shandong Science and Technology Small and Medium Enterprises Innovation Ability Improvement Project (No.2021TSGC 1240)the Key R&D Program of Shandong Province,China (No.2022TZXD002)the China Agriculture Research System Project (No.CARS-49)。
文摘Carotenoids play crucial physiological roles in animals.A comprehensive investigation into the mechanism of carotenoid metabolism in oysters will establish a theoretical foundation for further development of its carotenoid-rich traits.However,the information on the function of miRNA in β-carotene metabolism in oysters is limited.To elucidate the mechanisms underlying miRNA regulation of carotenoid metabolism in oysters,we compared the expressions of miRNA in digestive gland tissues of Pacific oyster(Crassostrea gigas)fed with aβ-carotene supplemented diet and a normal diet,respectively.A total of 690 candidate miRNAs in the Pacific oyster digestive gland tissues were identified,including 590 known miRNAs and 111 unknown miRNAs.Three differentially expressed miRNAs were obtained in the carotenoid-fed and normal groups,associated to 137 differentially expressed target genes.Moreover,the GO enrichment analysis revealed that the differentially expressed target genes were mainly involved in transmembrane transport activity.KEGG enrichment showed that the differentially expressed target genes were involved in ABC transport.Analysis of the mRNA-miRNA network revealed that novel0025 played a central role in carotenoid metabolism,and it was negatively correlated with the expression of 46 mRNAs.In addition,down-regulated expression of novel0025 upregulated the expression of the lipoprotein gene LOC105342186,suggesting a potential regulatory role in carotenoid metabolism.Our results provide useful information for elucidating the miRNA regulation mechanism during carotenoids metabolism in the Pacific oyster.
基金supported by the Shandong Seed Projectthe National Natural Science Foundation of China(No.31372524)Science and Technology Development Plan of Shandong Province,China(No.2014GHY 115002)
文摘There is an increasing requirement for traceability of aquaculture products, both for consumer protection and for food safety. There are high error rates in the conventional traceability systems depending on physical labels. Genetic traceability technique depending on DNA-based tracking system can overcome this problem. Genealogy information is essential for genetic traceability, and microsatellite DNA marker is a good choice for pedigree analysis. As increasing genotyping throughput of microsatellites, microsatellite multiplex PCR has become a fast and cost-effective technique. As a commercially important cultured aquatic species, Pacific oyster Crassostrea gigas has the highest global production. The objective of this study was to develop microsatellite multiplex PCR panels with dye-labeled universal primer for pedigree analysis in C. gigas, and these multiplex PCRs were validated using 12 full-sib families with known pedigrees. Here we developed six informative multiplex PCRs using 18 genomic microsatellites in C. gigas. Each multiplex panel contained a single universal primer M13(-21) used as a tail on each locus-specific forward primer and a single universal primer M13(-21) labeled with fluorophores. The polymorphisms of the markers were moderate, with an average of 10.3 alleles per locus and average polymorphic information content of 0.740. The observed heterozygosity per locus ranged from 0.492 to 0.822. Cervus simulations revealed that the six panels would still be of great value when massive families were analysed. Pedigree analysis of real offspring demonstrated that 100% of the offspring were unambiguously allocated to their parents when two multiplex PCRs were used. The six sets of multiplex PCRs can be an important tool for tracing cultured individuals, population genetic analysis, and selective breeding program in C. gigas.
基金supported by the grants from the National Natural Science Foundation of China(No.31772843)the Key Research and Development Program of Shandong Province(No.2016ZDJS06A06)the Industrial Development Project of Qingdao City(17-3-3-64-nsh)
文摘The shell color of Pacific oyster(Crassostrea gigas) is a desirable trait; but the nutritional studies on C. gigas with different shell colors have not been conducted. Through successive selective breeding, five shell color strains of black(B), purple(P), orange(O), golden(G) and white(W) C. gigas have been developed. The aim of this study was to evaluate the chemical composition and nutritional value of five shell color strains and one commercial population with a common color. The biochemical composition including moisture, total protein, glycogen, ash, total fat, fatty acids(FA), amino acids and minerals was detected. The results indicated that the protein(50.76%–56.57%) was the major component. The content of glycogen showed a significant difference between orange shell and golden shell strains, as well as between commercial population and golden shell strain. In addition, all shell color strains contained a large amount of essential amino acids(12.20–14.15 g(100 g)^(-1)), of them leucine(2.81–3.29 g(100 g)^(-1)) and lysine(2.79–3.28 g(100 g)^(-1)) were predominant. The oysters were rich in polyunsaturated fatty acids(42.26%–45.24% of total fatty acid) with high levels of DHA(18.53%–21.16% of total fatty acid) and EPA(17.23%–18.68% of total fatty acid). Significant differences of mineral contents(Mg, Zn, Fe and Cu) were identified among the six populations. These results indicated that C. gigas with different shell colors presented rich nutritional value with high protein, glycogen, essential amino acids and polyunsaturated fatty acids. The biochemical composition obtained in this study is useful for selective breeding of C. gigas with different shell colors.
基金supported by the grants from the National Natural Science Foundation of China(No.31372524)Shandong Seed Projectproject of Shandong Province(No.2016ZDJS06A06)
文摘Glycogen is important not only for the energy supplementary of oysters, but also for human consumption. High glycogen content can improve the stress survival of oyster. A key enzyme in glycogenesis is glycogen synthase that is encoded by glycogen synthase gene GYS. In this study, the relationship between single nucleotide polymorphisms(SNPs) in coding regions of Crassostrea gigas GYS(Cg-GYS) and individual glycogen content was investigated with 321 individuals from five full-sib families. Single-strand conformation polymorphism(SSCP) procedure was combined with sequencing to confirm individual SNP genotypes of Cg-GYS. Least-square analysis of variance was performed to assess the relationship of variation in glycogen content of C. gigas with single SNP genotype and SNP haplotype. As a consequence, six SNPs were found in coding regions to be significantly associated with glycogen content(P < 0.01), from which we constructed four main haplotypes due to linkage disequilibrium. Furthermore, the most effective haplotype H2(GAGGAT) had extremely significant relationship with high glycogen content(P < 0.0001). These findings revealed the potential influence of Cg-GYS polymorphism on the glycogen content and provided molecular biological information for the selective breeding of good quality traits of C. gigas.
基金supported by the grants from the National Natural Science Foundation of China (Nos. 3177 2843, 31741122)the Earmarked Fund for Agriculture Seed Improvement Project of Shandong Province (No. 2017LZGC009)the Fundamental Research Funds for the Central Universities (No. 201762014)
文摘The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas.
基金Supported by the National Natural Science Foundation of China (NO.40730845, 39825121)
文摘Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were detected in 46.7% of loci, accounting for 11.7% of the total alleles. Four loci did not segregate in Mendelian Ratios. Three linkage groups were identified among 7 of the 15 segregating loci. Fluorescence-based automated capillary electrophoresis (ABI 310 Genetic Analyzer) that used to detect the microsatellite loci, has been proved a fast, precise, and reliable method in microsatellite genotyping.
基金supported by the National High Technology Research and Development Program (2006AA10A409)the National Basic Research Program of China (2010CB126406)
文摘Mass selection for fast growth was conducted in three Pacific oyster (Crassostrea gigas) stocks from China, Japan and Korea using previously established lines (CS1, JS1, and KS1). To determine whether continuous progress can be achieved by selection for growth, the progeny of three second-generation Pacific oyster lines was selected for shell height and evaluated via a 400-day farming experiment. When harvested at the end of the experiment, the selected crosses of CS2, JS2, and KS2 lines grew by 9.2%, 10.2% and 9.6% larger than the control crosses, respectively. During grow-out stage, the genetic gain of three selected lines was (10.2 ± 1.4)%, (10.4 ± 0.3)%, and (8.4 ± 1.6)%, respectively; and the corresponding realized heritability was 0.457 ± 0.143, 0.312 ± 0.071 and 0.332 ± 0.009, respectively. These results indicated that the selection for fast growth achieved steady progress in the second generation of oyster. Our work provides supportive evidence for the continuity of the Pacific oyster selective breeding program.
基金Supported by the National High Technology Research and Development Program of China (863 Program, No. 2006AA10A409)the National Natural Science Foundation of China (No. 30571442)
文摘Five full-sib families of the Pacific oyster(Crassostrea gigas) larvae were used to study the mode of inheritance at eight microsatellite loci,and the feasibility of these markers for kinship estimate was also examined.All eight microsatellite loci were compatible with Mendelian inheritance.Neither evidence of sex-linked barriers to transmission nor evidence of major barriers to fertilization between gametes from the parents was shown.Three of the eight loci showed the presence of null alleles in four families,demonstrating the need to conduct comprehensive species-specific inheritance studies for microsatellite loci used in population genetic studies.Although the null allele heterozygotes were considered as homozygotes in the calculation of genetic distance,offspring from five full-sib families were unambiguously discriminated in the neighbor-joining dendrogram.This result indicates that the microsatellite markers may be capable of discriminating between related and unrelated oyster larvae in the absence of pedigree information,and is applicable to the investigation of the effective number of parents contributing to the hatchery population of the Pacific oyster.
基金supported by the Shandong Seed Project and the National Natural Science Foundation of China (31372524)
文摘Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population,as well as the experimental design for an association analysis.In this study,we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster(Crassostrea gigas).A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites,respectively.For syntenic marker pairs,no significant association was observed in the wild population;however,three significant associations occurred in the cultured population,and the significant LD extended up to 12.7 c M,indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population.The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population.Furthermore,the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster.The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.
基金Supported by the Agricultural Variety Improvement Project of Shandong Province(No.2019LZGC020),the National Natural Science Foundation of China(Nos.41906088,41876193,31802328)the National Key R&D Program of China(No.2018YFD0901400)+2 种基金the Special Funds for Taishan Scholars Project of Shandong Province,China(No.tsqn201812094)the Shandong Provincial Natural Science Foundation,China(No.ZR2019MC002),the Modern Agricultural Industry Technology System of Shandong Province,China(No.SDAIT-14-03)the Plan of Excellent Youth Innovation Team of Colleges and universities in Shandong Province,China(No.2019KJF004)。
文摘A variety of shell colors are one of the most fundamental characteristics of molluscs,which have importantly ecological and economic signifi cance.The Pacifi c oyster Crassostrea gigas is distributed in many sea areas around the world and also an aquacultured mollusc with high nutritional value.In this study,the whole soft body and the mantle tissue of black-shelled Pacifi c oyster(BSO)and white-shelled Pacifi c oyster(WSO)with starkly diff erent melanin contents were compared,and the diff erences in physiology and metabolism between BSO and WSO were analyzed.The results of physiological indicators suggested BSO show more melanin,more dry matter,more crude lipid content,and stronger ability to scavenge free radicals than WSO.The altered metabolites of glycerophospholipids,fatty acyls,and steroids revealed diff erent regulatory mechanisms of lipids.The correlation analysis of metabolomics and previously published RNAseq data suggested that BSO and WSO mainly diff ered in the basal metabolic processes,such as lipid,amino acid and purine metabolisms.This study provides insights into the changes in the physiological indictors and the metabolites of oysters with varying melanin content.
基金Supported by the Shandong Province Key R&D Program Project(No.2021LZGC029)the Major Scientific and Technological Innovation Project of Shandong Province(No.2019JZZY010813)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA24030105)the Qingdao Key Technology and Industrialization Demonstration Project(No.22-3-3-hygg-2-hy)the Earmarked Fund for China Agriculture Research System(No.CARS-49)。
文摘Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximately determine the nutrient content of the Pacific oyster Crassostreagigas.Samples of C.gigas from 19 costal sites were freeze-dried,ground,and scanned for spectral data collection using a Fourier transform NIR spectrometer(Thermo Fisher Scientific).NIRS models of glycogen and other nutrients were established using partial least squares,multiplication scattering correction first-order derivation,and Norris smoothing.The R_(C) values of the glycogen,fatty acids,amino acids,and taurine NIRS models were 0.9678,0.9312,0.9132,and 0.8928,respectively,and the residual prediction deviation(RPD)values of these components were 3.15,2.16,3.11,and 1.59,respectively,indicating a high correlation between the predicted and observed values,and that the models can be used in practice.The models were used to evaluate the nutrient compositions of 1278 oyster samples.Glycogen content was found to be positively correlated with fatty acids and negatively correlated with amino acids.The glycogen,amino acid,and taurine levels of C.gigas cultured in the subtidal and intertidal zones were also significantly different.This study suggests that C.gigas NIRS models can be a cost-effective alternative to traditional methods for the rapid and proximate analysis of various slaughter traits and may also contribute to future genetic and breeding-related studies in Pacific oysters.
基金supported by grants from the National Natural Science Foundation of China(Nos.31772843 and 31972789)the National Key R&D Program of China(No.2018YFD0900200)+1 种基金the Earmarked Fund for Agriculture Seed Improvement Project of Shandong Province(No.2017LZGC009)the Ocean University of China-Auburn University Joint Research Center for Aquaculture and Environmental Science。
文摘The color of Mollusca shells is one of the most important attributes to consumers.At the cellular level,black color is mainly from the melanin produced by melanocytes.The melanosome is a specialized membrane-bound organelle that is involved in melanin synthesis,storage,and transportation.How the complex pigmentation process in the Crassostrea gigas is established remains an open question.The objectives of this studies are to examine the morphological characteristics of melanosomes or melanin of mantle pigmentation in the Pacific oyster,thereby investigating its contribution to shell color.The results show that pigmented granules of the mantles vary among the three lobes,and the melanosomes at different stages are enriched in distinct cargo molecules,which indicate the remarkable difference between the marginal mantle and central mantle.Examination of mantle histology reveals that the mantle margin of the oyster is characterized by three different folds,including the outer secretory,middle sensory,and inner muscular fold.Ferrous ion chelating assays against the tyrosine hydroxylase indicate that a large amount of melanin is localized in the inner surface of the middle fold.Transmission electron microscopy analyses show that the mantle edge is composed of tall columnar and cuboidal epidermal cells and some pigmented melanocytes intersperse among these cells.The numbers of melanosomes among the three lobes are different.In the inner fold and the middle fold of the mantle,some single dispersion,or aggregation of melanosomes with different degrees of melanization are found in the outer surface.Numerous melanosomes are distributed in the epithelium of the outer fold of the mantle,and mainly are at the apical microvillar surface near the lumen.However,melanosomes are occasionally observed in the central mantle,and they are relatively less.This work provides new insights into the process of melanin deposit in the mantle and shell pigmentation in C.gigas.
基金Supported by the 100 Talents Program of Chinese Academy of Sciencesthe Development Plan of Science and Technology in Shandong Province(No.2012GGA06032)the Key Deployment Program of Chinese Academy of Sciences(No.KZZD-EW-14-03)
文摘Heavy metal pollution can affect the immune capability of organisms. We evaluated the effect of cadmium （Cd） on the defense responses of the Pacific oyster Crassostrea gigas to Listonella anguillarum challenge. The activities of several important defensive enzymes, including superoxide dismutase （SOD）, glutathione peroxidase （GPx）, acid phosphatase （ACP）, Na＋, K＋-ATPase in gills and hepatopancreas, and phenoloxidase-like （POL） enzyme in hemolymph were assayed. In addition, the expression levels of several genes, including heat shock protein 90 （IrtSP9~））, metallothionein （MT）, and bactericidal/permeability increasing （BPI） protein were quantified by fluorescent quantitative PCR. The enzyme activities of SOD, ACP, POL, and GPx in hepatopancreas, and the expression of HSP90 were down-regulated, whereas GPx activity in the gill, Na＋, K＋-ATPase activities in both tissues, and MT expression was increased in Cd- exposed oysters post L. anguillarum challenge. However, BPI expression was not significantly altered by co-stress of L. anguillarum infection and cadmium exposure. Our results suggest that cadmium exposure alters the oysters＇ immune responses and energy metabolism following vibrio infection.
基金supported by the National Natural Science Foundation of China (No. 31172403)。
文摘Polyploid breeding is widely used in various marine species. Low salinity treatment is an effective method of inducing triploid of bivalve mollusks. In this study, RNA-seq was performed to determine genes and pathways involved in hyposaline adaption and cell division of Pacific oyster(Crassostrea gigas) zygotes, trying to better understand the possible molecular mechanism of hypo-osmotic induction. A total of 26965 unigenes were generated in the de novo assembly of clean Illumina reads with an average length of 934 bp and N50 of 1721 bp. Of 3024 differentially expressed genes(DEGs), 2501 were up-regulated and 523 were downregulated. GO(Gene Ontology) annotation and KEGG(Kyoto Encyclopedia of Genes and Genomes) pathway analysis of these DEGs revealed that these DEGs participate a variety of biological processes including osmoregulation, cytoskeleton organization, cell survival and death, and substantially modulate cell proliferation and embryonic development. In summery, RNA-seq methodology was applied for the first time to demonstrate hypotonic-induced transcriptomic alteration in oyster zygotes. Our findings not only interpreted the relatively high mortality of induced larvae, but also provided a valuable reference for further investigations on the mechanism of hyposaline induction, thus should aid to the application of low salinity in triploid induction in large scale aquaculture in future.
