Shellfish In China Research Articles

Comparative Cytogenetic Analysis of Diploid and Triploid Pacific Abalone, Haliotis discus hannai

Introduction: The Pacific abalone, Haliotis discus hannai, is one of the most commercially important marine shellfish in China. Cell engineering breeding is an important tool in abalone genetic breeding, and the triploids obtained through this method have high commercial value. However, current research mainly focuses on establishing induction methods and evaluating the growth traits of triploids, while there is a lack of basic research on triploid cytogenetics. Method: In this study, Cytogenetic analysis of triploid Haliotis discus hannai larvae (produced by chemical treatment) and diploid larvae was performed. Result: The results showed that triploid H. discus hannai had a chromosome number of 3n = 54, consisting of 30 metacentric (m) and 24 submetacentric (sm) chromosomes, while the diploids had a chromosome number of 2n = 36, consisting of 20 metacentric (m) and 16 submetacentric (sm) chromosomes. Notably, both triploids and diploids displayed variation in the number of NORs and/or their diameter. The average number of NORs in triploid was significantly higher than that in diploids (p < 0.05), but the average diameter of NORs of triploid was no significant different from that of diploid (p > 0.05). Additionally, 5S rDNA localization to 3 submetacentric chromosomes was observed in triploids, compared to 2 submetacentric chromosomes in diploids. The number of 18S rDNA sites displayed positional conservancy and quantitative variability in both diploids and triploids. Specifically, 18S rDNA was found at the end of the chromosome in both groups, with triploids exhibiting a significantly higher number of loci than diploids (p < 0.01). Conclusion: This study provides valuable insights into the cytogenetic characteristics of triploid H. discus hannai, which could facilitate further research on the stability of the chromosome set in this species.

Assessing potential driving factors of the ecosystem service value of mariculture shellfish in China using a structural equation modeling approach

China is one of the major mariculture countries for shellfish in the world and provides more than 70% of the total global shellfish production. However, there is limited knowledge of the potential driving factors of the ecosystem service value of mariculture shellfish in China. Understanding what factors and how they drive the ecosystem can provide reference for further improving the ecosystem service value of mariculture shellfish, which is both theoretically and practically important for promoting the development of marine fishery economy in China. In this study, data of six major mariculture shellfish species in nine coastal provinces of China from 2009 to 2020 were analyzed using a structural equation modeling approach to quantify the effects of resource distribution characteristics and market demand on the ecosystem service value of mariculture shellfish in China. The results indicated that both resource distribution characteristics and market demand are important driving factors of the ecosystem service value of mariculture shellfish in China. Specifically, from the perspective of path coefficient, market demand plays a more important role (0.58) than resource distribution characteristics (0.36) in influencing the ecosystem service value of mariculture shellfish in China. Therefore, the research results for shellfish marine culture can be summarized as: (1) to actively respond to changes in shellfish market demand, (2) to enhance development planning for coastal shellfish cultivation area, and (3) to strengthen systematic management of mariculture shellfish resources. Results of this study could provide theoretical support and serve as a basis for promoting sustainable development of shellfish culturing industry and fisheries economy in China.

Phenotypic evaluation of two genetically improved strains selected from the reciprocal hybrids of Crassostrea gigas and C. angulata

The Pacific oyster (Crassostrea gigas) is one of the most economically important aquaculture shellfish in China, but further development of its industry is constrained by germplasm degradation and summer mass mortality episodes. To this end, a three-generation mass selection on the reciprocal hybrids, GA-C. gigas ♀ × C. angulata ♂ and AG-C. angulata ♀ × C. gigas ♂, was conducted to develop two strains (GA and AG selected strain) with fast-growing and warm-adapted characteristics. The aim of the present study was to determine whether the genetic improvement in growth, survival and thermal tolerance could be achieved by mass selection. For shell height, a genetic gain of 7.77–14.60%, a selection response of 0.67–0.91, and a realized heritability of 0.39–0.57 were observed in the selected strains after three generations of selection; for total weight, a genetic gain of 11.33–14.85%, a selection response of 0.73–1.06, and a realized heritability of 0.41–0.67 were observed in the selected strains after three generations of selection. The significant selection response of growth traits suggests the potential for genetic improvement of growth traits in both strains. With selection, the LT50 increased from 41.81 °C to 42.10 °C in the GA selected strain and from 41.61 °C to 42.06 °C in the AG selected strain. By the F3 generation, the summer survival rates of the GA and AG selected strain were 10.53% and 8.98% higher than that of the control strain, respectively, and 20.80% and 18.14% higher than that of the C. gigas strain, respectively. The consistent results of LT50 and summer survival suggest that thermotolerance selection may provide a viable strategy for improving summer survival in oysters. After three generations of selection, the total yield of the two strains increased by 29.63% and 19.78%, respectively, compared to C. gigas strain. This study provides a source of superior strains for the sound development of the oyster industry and can be used as a reference for shellfish breeding strategies.

Characterization, expression profiling, and estradiol response analysis of DMRT3 and FOXL2 in clam Cyclina sinensis

The clam Cyclina sinensis is one of the important economical aquaculture shellfish in China. However, the mechanisms of sex determination and differentiation in C. sinensis have not been fully studied. In this study, full-length cDNAs of DMRT3 and FOXL2 were cloned and functionally characterized. The ORF region of CsDMRT3 consists of 1137 nucleotides, which encode 378 amino acids contains a conserved DM domain of DMRT family. The ORF region of CsFOXL2 is 1245 bp, encodes 414 amino acids, and contains a conserved FH domain. Tissue-specific expression results showed that the higher expression level of CsDMRT3 and CsFOXL2 was found in the ovary and testis of C. sinensis. The expression levels of CsDMRT3 and CsFOXL2 also peaked at the maturation stage of male and female gonadal development, respectively. Moreover, the expression levels of CsDMRT3 and CsFOXL2 were significantly higher in the trochophore and D-larval stages than in other stages. The transcript levels of CsDMRT3 reached the highest level at 11 months of age, while the CsFOXL2 reached the highest level at 7 months of age. In estradiol-treated experiments, the expression levels of CsDMRT3 and CsFOXL2 in the gonads were highest at 5 µg/L estradiol treatment, and histologically, it was observed that the oocytes diameters became larger with increasing estradiol concentration. These results suggest that CsDMRT3 and CsFOXL2 play an important role in gonadal development and sex differentiation of C. sinensis.

Ecological value of mariculture shellfish resources in China: Assessment and management

Under the background of global climate change and carbon reduction commitment, it is of great significance to study the ecological value of mariculture shellfish resources. China is the largest country in terms of mariculture shellfish. In this study, the ecological value of mariculture shellfish in China was dynamically evaluated after determining the shellfish ecological value composition and the value calculation coefficients. On this basis, the dynamic characteristics of the mariculture shellfish ecological values during 2010–2019 were revealed, as well as the economic problems and reasons behind. The study results indicated that the average ecological value of mariculture shellfish in China showed an overall upward trend. The core values of mariculture shellfish are carbon sequestration and water purification, which displayed an increasing trend. The habitat value of mariculture shellfish showed a significant downward trend because of the reduction of aquaculture area and the increase of aquaculture density. Additionally, the increase in the heavy metal enrichment value was due to the rising production of mariculture shellfish and the rising price of processing heavy metals in China. Therefore, innovative management policies were proposed including introducing a third-party independent consultant, building a carbon-sink shellfish demonstration zone, improving a carbon-sink market transaction mechanism, establishing a nitrogen credit market, and controlling the full-cycle management of mariculture shellfish based on biotechnology and blockchain technology. It was hoped to promote the healthy development of the mariculture shellfish industry and make China's contribution to the world's carbon emission reduction.

Transitions, challenges and trends in China's abalone culture industry

AbstractAbalone species are economically important shellfish in China's aquaculture industry. In 2020, China's abalone aquaculture production was 203,500 tonnes, accounting for nearly 90% of total global production. However, many problems have accompanied the rapid development of this industry, including a reduction in near‐shore space suitable for culture and the risk of exposure of farms to natural disasters such as typhoons and red tides. In addition, high temperatures and low oxygen levels resulting from global climate change are causing increased abalone mortality in summer. In this review, the culture patterns and characteristics used in different countries are compared with respect to larvae nurseries, intermediate juvenile culture and the grow‐out phase. Next, the transitions and challenges in China's abalone culture industry over the past 60 years are summarized. Finally, a coordinated land‐sea program for reducing solid waste emissions into the water and increasing carbon sinks is suggested based on the ‘Carbon Neutrality’ theory. Under the framework of the program, new facilities, technologies and models should be created to achieve increased mechanization and a greater understanding of the abalone aquaculture industry as soon as possible. This review provides references and data to support the scientific planning and mapping of China's abalone culture industry as well as the transition of China's perceived identity from a major fishery country to a strong fishery power with an awareness of environmental protection and resource use.

Effects of Short-Term Salinity Stress on Ions, Free Amino Acids, Na+/K+-ATPase Activity, and Gill Histology in the Threatened Freshwater Shellfish Solenaia oleivora

Salinity is an important ecological factor affecting the osmolality of aquatic animals. Solenaia oleivora is an endemic and economically important freshwater shellfish in China. However, its osmotic response and osmoregulatory mechanisms under high salinity stress are still unclear. In this study, S. oleivora was exposed to saline water (salinity: 2.2‰) for 3 h, 6 h, 12 h, 24 h, and 48 h, and then the changes in osmolality, ion concentrations, free amino acid (FAA) content, Na+/K+-ATPase (NKA) activity, and gill histology were analyzed. The hemolymph osmolality increased from 3 h after salinity stress and stabilized between 24–48 h. Na+ in the hemolymph increased from 24 h after salinity stress, and Cl− increased from 3 h. The content of total FAAs in the hemolymph increased after salinity stress. The content of alanine, glycine, glutamine, proline, and other FAAs increased after salinity stress. NKA activity in the gill, hepatopancreases, adductor muscle, and axe foot decreased during 3–48 h of salinity stress. The gill filament space increased and the number of gill cilia decreased after salinity stress. Principal component analysis (PCA) showed that the first two principal components (PC1 and PC2) cumulatively explained 77.6% of the total variation. The NKA activity was positively associated with PC1, while the ion concentration and most FAAs were negatively associated with PC1. Thus, these results indicated that S. oleivora is an osmoconformer, and inorganic ions, FAA, NKA, and gill structure changes play an important role in its osmoregulation.

Histological, physiological, and transcriptomic responses of hepatopancreas to air exposure in asian freshwater clam Corbicula fluminea.

Corbicula fluminea (C. fluminea) is an important freshwater economy shellfish in China, but it often suffers from air exposure during transportation. In this study, we investigated the histological, physiological (mainly including respiratory metabolism, antioxidant capacity, and immune function), and transcriptomic responses of hepatopancreas in C. fluminea to different times of air exposure. At histological level, air exposure caused vacuolation of digestive cells (24–96 h) and enlargement of digestive tubule lumen (6–96 h) in hepatopancreas. At physiological level, the activities of enzymes related to glycolysis (hexokinase and pyruvate kinase) and anaerobic respiration (lactate dehydrogenase) were increased first (6–24 h) of air exposure, then came back to normal level or even decreased. The activity of aerobic respiration-related enzyme (succinic dehydrogenase) began to reduce from 24 h of air exposure. The activities of antioxidant enzymes (superoxide dismutase and catalase) were enhanced during 6–48 h of air exposure and then returned to control level or even inhibited. The content of malondialdehyde (MDA) increased from 96 h of air exposure. The activities of immune-related enzymes (acid phosphatase and alkaline phosphatase) increased during 6–48 h, then returned to normal or began to decline. At transcriptome level, 44 differentially expressed genes (DEGs) in the hepatopancreas were identified after 96-h air exposure. Among these DEGs, 8 were associated with glycolysis, TCA cycle, immune, and antioxidant, and were downregulated after 96-h air exposure. Taken together, these findings illuminated the response of C. fluminea to air exposure at histological, physiological, and transcriptomic levels, which will be beneficial to the aquaculture and transportation of C. fluminea.

Digestion behavior of a polysaccharide from Cyclina sinensis: An explanation for the discrepancy in its immunostimulatory activities in vitro and in vivo.

Although numerous polysaccharides have demonstrated potential immunostimulatory activities in in vitro models, only a few of them successfully stimulate the immune system in vivo. In order to explore the possible reasons for the activity loss of polysaccharides in in vivo models, the immunostimulatory activities in vitro and in vivo and the digestion behavior of a polysaccharide from Cyclina sinensis (CSP) were investigated in the present study. CSP showed obvious immunostimulatory activity in a RAW 264.7 cell model. In in vitro experiment, CSP did not exhibit cytotoxicity at concentrations of ≤10 µg/ml, and significantly increased NO production at concentrations of 0.4-10 µg/ml, suggesting CSP processes immunostimulatory activity in vitro. Further investigation using simulated digestion model indicated that CSP could bind with the protein in the digestive fluids to form precipitate in both the stomach and small intestine, and it could be seriously degraded by amylase during the digestion in the small intestine. Furthermore, the in vivo immunostimulatory activity evaluation demonstrated CSP had no effect on immunosuppressed mice as indicated by the body weight, thymus and spleen indexes, and TNF-α, IL-1β, IL-6, and IL-10 mRNA expression. Thus, the present study indicates that the degradation and precipitation of CSP in the digestive tract are the possible reasons for the activity loss of CSP after digestion. PRACTICAL APPLICATION: Cyclina sinensis is the common aquatic shellfish in China and plays an important role in the marine aquaculture industry. Cyclina sinensis polysaccharide (CSP) is the main active component of C. sinensis. The structure characterization and immunostimulatory activity of a purified fraction of CSP (CSP-1) and the effect of digestion on CSP and its immunostimulatory activity were studied. The result of this study promotes the understanding of the nutritional function effects and provides a scientific reference for the rational development and high-value utilization of C. sinensis.

Genetic Evaluation of Growth and Survival-Related Traits in Yesso Scallop Patinopecten yessoensis in Sea-Based Culture System

Worldwide, the bivalve aquaculture industry has realized or recognized the potential gains from selective breeding programs using phenotypic and pedigree data. Yesso scallop Patinopecten yessoensis are among the most important commercial shellfish in China. A family-based breeding program to investigate the genetic variations for growth and survival-related traits at suspended and bottom environments of sea-based culture systems was reported in this study. We proposed and conducted a novel phenotyping technique to longitudinally evaluate the shell heights in the yesso scallop. At harvest after rearing for 20 months, the individual shell heights at 6, 10, 16, and 20 months were simultaneously obtained by the growth rings in the outer shells of the animals. Meanwhile, the body weight (BW) of the survived individuals at harvest was also recorded. Variance components and genetic parameters for growth and survival-related traits were estimated using an animal and threshold model, respectively. In the suspended environment, the heritability estimates for BW and shell heights at specific ages ranged from moderate to high (0.328–0.853). The estimated correlations between shell heights at contiguous ages were consistently high, ranging from 0.890 to 0.958 but decreased with increasing intervals between ages (0.496–0.828). The estimated correlations between shell heights at contiguous ages and BW at harvest were similar, ranging from 0.535 to 0.983. The heritability estimates for individual survival at harvest were at a low level of 0.128 by the probit-threshold model. While at the bottom environment, estimates of heritability for growth and survival-related traits were similar but slightly lower than those at the suspended environment. Furthermore, the genetic correlation for BW between the two environments was very small, which probably indicates genotype-by-environment interaction effects for growth in the yesso scallop. The study can provide prior information, which might develop a new idea for selection in this species. The results are discussed concerning selection work with yesso scallop, and solutions for accurate estimation of genetic parameters and increasing genetic gain are also outlined.

Cyp17a effected by endocrine disruptors and its function in gonadal development of Hyriopsis cumingii

Estrogens and androgens that coexist in the aquatic environment could potentially affect shellfish, however, endocrine disrupting effects of them in shellfish are significant. As an important aquaculture shellfish in China, Hyriopsis cumingii has remarkable economic benefits. In this study, the effects of endocrine disrupting chemicals on the steroid synthase Hc-Cyp17a in the male and female gonads of the H. cumingii were assessed by exposing juvenile mussels to cultured waters containing 17β-Estradiol (E2) and 17α-Methyltestosterone (MT) for 28 days. At the same time, the E2 content in the four stages of gonadal development, the expression changes of Hc-Cyp17a in gonadal development and its localization in the mature gonad were measured to explore the relationship between genes and hormones. The results showed that both E2 and MT at 50 ng/L and 200 ng/L could affect the transcription level of Hc-Cyp17a, which was inhibited initially and promoted in post-development. E2 content was positively correlated with gonadal development stage, which was in mussel. By tracing the expression of Hc-Cyp17a, difference was found during different developmental periods. The expression level in ovary was higher than that in testis during gonadal development of 1/ 2/ 3-year-old mussels and showed an increasing trend with age. Furthermore, the expression levels in 6 tissues of mature individuals were measured and it showed that there was a significant difference between male and female in the gonads (p < 0.01). In situ hybridization, it suggested that Hc-Cyp17a was significantly signaled in the follicular wall and oocyte of female and in the follicular membrane of testis, respectively. These results could play a vital role in assessing and understanding the effects of aquatic environment on the endocrine system of H. cumingii.

Calibration of the Discrete Element Method Parameters in Living Juvenile Manila Clam (Ruditapes philippinarum) and Seeding Verification

The Manila Clam is an important economic shellfish in China’s seafood industry. In order to improve the design of juvenile Manila Clam seeding equipment, a juvenile clam discrete element method (DEM) particle shape was established, which is based on 3D scanning and EDEM software. The DEM contact parameters of clam-stainless steel, and clam-acrylic were calibrated by combining direct measurements and test simulations (slope sliding and dropping). Then, clam DEM simulation and realistic seeding tests were carried out on a seeding wheel at different rotational speeds. The accuracy of the calibrated clam DEM model was evaluated in a clam seeding verification test by comparing the average error of the variation coefficient between the realistic and simulated seeding tests. The results showed that: (a) the static friction coefficients of clam-acrylic and clam-stainless steel were 0.31 and 0.23, respectively; (b) the restitution coefficients of clam-clam, clam-acrylic, and clam-stainless steel were 0.32, 0.48, and 0.32, respectively. Furthermore, the results of the static repose angle from response surface tests showed that when the contact wall was acrylic, the coefficient rolling friction and static friction of clam-clam were 0.17 and 1.12, respectively, and the coefficient rolling friction of clam-acrylic was 0.20. When the contact wall was formed of stainless steel, the coefficient rolling friction and static friction of clam-clam were 0.33 and 1.25, respectively, and the coefficient rolling friction of clam-stainless steel was 0.20. The results of the verification test showed that the average error between the realistic and simulated value was &lt;5.00%. Following up from these results, the clam DEM model was applied in a clam seeding simulation.

The Characteristic of Critical Genes in Neuroendocrine System and Their Regulation on Food Habit Transition and Metamorphosis of Veined Rapa Whelk Rapana venosa (Valenciennes, 1846)

Metamorphosis is a critical developmental event in mollusks, and neuroendocrine system plays an essential role in this process. Rapana venosa is an economically important shellfish in China, but the artificial technology of R. venosa aquaculture is limited by metamorphosis. As a carnivorous gastropod, food habit transition makes the mechanism of R. venosa metamorphosis more complex. To investigate the changes in the neuroendocrine system and to reveal its role in regulating the food habit transition and metamorphosis of R. venosa, we cloned the cDNA sequences encoding 5-hydroxytryptamine receptor (Rv-5HTR), nitric oxide synthetase (Rv-NOS) and cholecystokinin receptor (Rv-CCKR), and investigated their expression by quantitative real-time PCR analysis, and explore the spatio-temporal changes of 5-HT protein expression using Immunohistochemical (IHC) analysis. The expression of the three geens was significantly increased in the early intramembrane veliger stage, which indicates that the three genes are related to the development of digestive system. Additionally, expression of the three genes was decreased after metamorphosis, while Rv-NOS and Rv-CCKR were increasingly expressed in competent larvae, which may help the larvae find suitable environments and promote digestive system development for metamorphosis, and the result of 5-HT IHC analysis also reflects the development of neuroendocrine system. Furthermore, results show that CCK can effect the expression of digestive enzyme, NOS and 5-HT receptor. Finally, based on the present results, we hypothesized that CCK and CCK receptor may be critical regulatory factors of food habit transition and metamorphosis. These results might provide information on the development of neuroendocrine system of R. venosa, and new insight into the regulation of the food habit transition and metamorphosis of gastropods.

Expression and activity of critical digestive enzymes during early larval development of the veined rapa whelk, Rapana venosa (Valenciennes, 1846)

Metamorphosis is a vital developmental event in the life cycle of molluscs and involves extensive morphological and physiological changes. Remodeling of the digestive system is suggested to occur anticipatorily to enable the larva to shift its diet (from filter feeding on microalgae to feeding on small bivalves) after metamorphosis. Changes in the profiles and activities of digestive enzymes, the main executors of digestion, can reflect substantial remodeling of the digestive system. Artificial aquaculture of Rapana venosa, an important commercial shellfish in China, has been hampered because the transition of its food habit during metamorphosis makes determining the timing and dose for bait regulation difficult. In the present study, full-length cDNA sequences encoding cellulase and trypsin were characterized, and cellulase and trypsin mRNA expression levels were analyzed. Additionally, patterns in the activities of six digestive enzymes, including trypsin and cellulase, were investigated throughout the early developmental stage of R. venosa. In the present study, the full-length cDNA of the cellulase gene, comprising 2,086 bp, was found to contain a 1,719-bp open reading frame encoding 572 amino acids, and the full-length cDNA of the trypsin gene was found to be 1,587 bp in length and contained an 855-bp open reading frame encoding 284 amino acids. Quantitative real-time PCR showed that the cellulase levels in R. venosa increased beginning at the early intramembrane veliger stage, whereas cellulase activity was significantly increased in the one-spiral whorl stage. The mRNA expression and activity of trypsin were greatly increased in the juvenile stage (postlarva), whereas those of cellulase were decreased during this stage, which indicated functional changes in the digestive system during larval food habit transition. Our results showed that remodeling of the digestive system occurs prior to metamorphosis and suggest that animal bait should be provided as early as possible to R. venosa in the four-spiral whorl stage to meet its nutritional requirements for the development of its digestive system and to ensure successful metamorphosis of competent larvae.

Genetic variation and population structure of different geographical populations of Meretrix petechialis based on mitochondrial gene COI

The hard clam (Meretrix petechialis) is a commercially important shellfish in China. To provide valuable insights into management and conservation of M. petechialis, we investigated the genetic variation and population structure of M. petechialis by analysing samples from nine geographical populations. In this study, the genetic diversity and differentiation of nine populations of M. petechialis were assessed using the mitochondrial cytochrome oxidase subunit I (mtCOI) gene. A total of 90 COI sequences were obtained and each COI sequence was 699 bp in length. Fifty-one haplotypes were identified with 10 haplotypes shared among populations. The haplotype diversity was highest in Fujian, Panjin and Jiangsu (0.9778 ± 0.0540) and lowest in Dalian (0.7778 ± 0.1374). The nucleotide diversity was highest in Panjin (0.453401 ± 0.240463) and lowest in Jiangsu (0.006213 ± 0.004141). Neutral test (Fu's Fs) and mismatch distribution analysis revealed that the hard clam experienced a population expansion event. Analysis of molecular variance (AMOVA) indicated that 91.7% of the genetic variance was within populations and 0.52% of the variance was among populations, demonstrating significant genetic differentiation among populations (P < 0.05). The neighbour-joining tree showed that the haplotypes were not clustered according to the geographical location, but some haplotypes from the same or neighbouring locations grouped together. The results obtained in this study provide useful information on the genetic diversity and population structure of M. petechialis and shed light on the management and protection of resources of M. petechialis in the northwestern Pacific.

Characterization of the complete mitochondrial genome of Pacific abalone Haliotis discus hannai

The complete mitochondrial genome of Pacific abalone Haliotis discus hannai, an economically valuable shellfish in China, was sequenced and analyzed. The mitogenome was 16,716 bp in length and contained 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and a putative control region. The gene arrangement and orientation were identical with other Haliotis species. Phylogenetic tree was constructed based on 13 PCGs of 7 Haliotidae species to assess their phylogenetic relationship, the tree revealed that H. discus hannai was more closely to H. rufescens and H. iris.

Prevalence of foodborne pathogens isolated from retail freshwater fish and shellfish in China

In 2016, the nationwide food safety surveillance was conducted on fresh water fish and shellfish in China. The prevalence of Vibrio parahaemolyticus, Vibrio cholerae, Salmonella, and L. monocytogenes were 19.0% (613/3226), 3.4% (110/3226), 3.8% (124/3226), and 2.5% (80/3226), respectively. The tdh and trh genes were detected in 19 (2.6%) and 24 (3.3%) of the 718 V. parahaemolyticus isolates, respectively. All V. cholerae strains were confirmed as non-O1/O139 serogroups. The most predominant Salmonella serotypes were S. Stanley, S. Thompson, S. Litchfield, S. Typhimurium, S. Virchow, S. Carrau, and S. Infantis. The results of this comprehensive survey showed contamination by four pathogens in fresh water fish and shellfish in China for the first time. The study indicated a need for proper handling, storage, and cooking of freshwater fish and shellfish. Further risk reduction assessment and implementation are necessary to reduce foodborne disease in China.

Mapping the value chain of imported shellfish in China

This study explores the value chain structure and chain activities of the imported shellfish industry in China. Data were collected from face-to-face semi-structured interviews in Guangzhou (n = 30) and Shanghai (n = 23) and a face-to-face survey in Shanghai (n = 71). Data analysis employed both content and descriptive analyses. Results show that the value chain is composed of several important members including foreign exporters, Chinese importers, wholesalers, resellers and clearance companies. Business partnership is the main channel by which marketing information is gained by chain members. Relationships are quite stable among the chain members, with quality, price and credit items being the most important factors that influence chain relationships. It seems that imported shellfish from some developed countries (e.g. Canadian and U.S. lobsters) have reached a market saturation in China's first-tier cities (e.g. Guangzhou and Shanghai) and relevant chain members face fierce competition. E-commerce is still not mature enough as a tool for the marketing development of imported shellfish in China.

Consumer adoption of sustainable shellfish in China: Effects of psychological factors and segmentation

China's large and increasing demand for aquatic products has had a significant effect on the sustainability of global water ecosystems. This study explored the effects of psychological factors and segmentation on Chinese consumers' adoption of sustainable shellfish. Data were collected by using a web-based questionnaire in three Chinese cities: Beijing, Guangzhou and Chongqing (with a total sample size of 643). Descriptive analysis, cluster analysis, confirmatory factor analysis and structural equation modeling were used for data analysis. Chinese consumers' subjective norms, personal norms, attitudes toward shellfish and attitudes toward water environment were significant psychological factors influencing their purchase intentions toward sustainable shellfish. Two consumer segments were identified: Sustainable-shellfish-pioneer (47.28%) and Sustainable-shellfish-conservative (52.72%). These two segments had significant differences in the purchase intentions for specific sustainable shellfish species, the effects of psychological factors on purchase intentions toward shellfish, and socio-demographic distributions (including income, occupation and marriage status). These first hand findings can help global shellfish producers, marketers and policy-makers to develop appropriate sustainable development strategies and policies for their shellfish resources when exploiting the huge market.

Analysis of evolutionary relationships of important shellfish in China based on the DNA barcoding COI gene

PDF HTML阅读 XML下载 导出引用 引用提醒 利用DNA条形码COI基因分析我国重要贝类系统进化关系 DOI: 作者: 作者单位: 1. 农业农村部海洋渔业可持续发展重点实验室, 中国水产科学研究院黄海水产研究所, 山东 青岛 266071;2. 海洋渔业科学与食物产出过程功能实验室, 青岛海洋科学与技术国家实验室, 山东 青岛 266273;3. 水产科学国家级实验教学示范中心, 上海海洋大学, 上海 201306 作者简介: 赵庆(1992-),男,研究生,研究方向为贝类遗传与免疫.E-mail:sjxapy@163.com 通讯作者: 中图分类号: S917 基金项目: 科技部科技基础性工作专项（2013FY110700）；国家水产种质资源共享服务平台（2017DKA30470）. Analysis of evolutionary relationships of important shellfish in China based on the DNA barcoding COI gene Author: Affiliation: 1. Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China;2. Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Techuology, Qingdao 266273, China;3. National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:DNA条形码旨在通过PCR技术获得一段DNA序列，在物种水平上对现存生物类群和未知生物材料进行识别和鉴定。线粒体细胞色素C氧化酶I（COI）基因是常用DNA条形码基因之一，为研究COI基因作为DNA条形码在贝类系统进化中的评估效果，本文利用PCR技术扩增获得了60个贝类物种的353条COI基因序列，通过聚类法构建了neighbor-joining（NJ）进化树，同时还对7个物种不同地理群体的遗传进化情况进行了分析。结果表明，选用的COI基因引物在大多数贝类中通用性较强，除在珍珠贝目中的扩增效率只有10%以外，在整个研究中扩增效率达到82.7%；60个物种中除太平洋潜泥蛤（Scapharca broughtoni）等8个物种在进化树中的进化地位与传统系统分类具有一定差别外，其他物种的聚类关系与传统分类基本一致；对7个物种、共26个地理群体的聚类分析发现，COI基因基本能对同一物种的不同地理群体进行聚类，只有极个别群体或群体中的某个个体存在聚类混乱现象。综上所述，COI基因在一定程度上适用于贝类物种鉴别和系统发育研究，丰富了COI基因在物种鉴别应用中的科学数据。 Abstract:DNA barcodes can be used to identify existing biological groups and unknown biomaterials through shorter DNA sequences using polymerase chain reaction (PCR). The mitochondrial cytochrome coxidase I (COI) gene is one of the commonly used DNA barcoding genes. In the present study, to analyze the effectiveness of the COI gene for DNA barcoding in mollusk evolution, 353 sequences of 60 species belonging to 13 orders and 33 families were obtained by PCR amplification for clustering analysis. A neighbor-joining (NJ) phylogenetic tree was constructed by Mega, and the genetic evolution of seven species from different populations was also analyzed. The results showed that the universal primers of the COI gene were highly versatile for most shellfish. Although the amplification efficiency of primers in Pterioida was only 10%, it reached 82.7% for the individuals. Except for the evolutionary status of eight species, such as , the clustering relationships of other species were similar to results obtained using traditional methods. Based on the clustering analysis of 7 species from 26 geographical groups, it was found that the COI gene generally clustered the different geographical groups of the same species first, and some individuals in the population or group had clustering disorder. In conclusion, the COI gene could be applied to the identification and phylogenetic studies of shellfish species to a certain extent, which would enhance the role of the COI gene in practical applications of species identification, and provide reference data for the construction of shellfish DNA barcoding databases. 参考文献 相似文献 引证文献