Fenneropenaeus Chinensis Research Articles

Molecular characterization of prohibitins and their differential responses to WSSV infection in hemocyte subpopulations of Fenneropenaeus chinensis

In our previous work, prohibitin1 (PHB1) was identified to be only expressed in granulocytes of Fenneropenaeus chinensis. In order to elucidate the potential immunological properties of prohibitins in hemocyte subpopulations, in this paper, the full-length cDNAs of PHB1 and PHB2 were firstly cloned from F. chinensis using rapid amplification of cDNA ends approach, and they were designated FcPHB1 and FcPHB2, respectively. Based on the sequence analysis and multiple sequence alignment, FcPHB1 and FcPHB2 were members of SPFH protein family. By quantitative real-time RT-PCR, the higher mRNA transcription levels of FcPHB1 and FcPHB2 were detected in intestine and hemocytes of F. chinensis, and these two genes in hemocytes were significantly up-regulated upon WSSV infection. The FcPHB1 and FcPHB2 were recombinantly expressed in Escherichia coli BL21 (DE3), and employed as immunogens to produce the polyclonal antibodies (PAbs) in rabbits. Indirect immunofluorescence assay (IFA) revealed that the FcPHB1 and FcPHB2 were located both in the cytoplasm and nuclei of hemocytes, which could also be specifically recognized by the PAbs against FcPHB1 or FcPHB2 in Western blot. Interestingly, it was found that FcPHB1 and FcPHB2 were only expressed in the granulocytes of heathy shrimp and highly expressed in the WSSV-infected granulocytes, however only weak expressions of FcPHB1 and FcPHB2 were observed in the hyalinocytes of WSSV-infected shrimp. Meanwhile, silencing of FcPHB1 and FcPHB2 genes were performed by small interfering RNA, and the results showed that the WSSV copies in hemocytes were increased by knockdown of either FcPHB1 or FcPHB2, and the cumulative mortalities of shrimp in the silenced groups were also markedly increased. These results demonstrated that FcPHB1 and FcPHB2 played important roles in anti-WSSV infection, and their differential expression characteristics in hemocyte subpopulations provided a further understanding of the immune functions of granulocytes and hyalinocytes.

Molecular characterization of myostatin and its inhibitory function on myogenesis and muscle growth in Chinese Shrimp, Fenneropenaeus chinensis.

Myostatin (Mstn) inhibits muscle growth in vertebrates with endoskeleton, but it is still inconclusive that Mstn is a positive or negative regulator in crustacean with exoskeleton, and little information was available for its function on myogenesis. In this study, we identified and characterized the Mstn from Fenneropenaeus chinensis (FcMstn), and investigated its function on myogenesis and muscle growth. Two different cDNA sequences (2628bp and 2604bp) encoding for slightly different sizes of proteins were obtained for FcMstn, containing 86bp of 5' untranslated regions (UTR) and 1258bp of 3' UTR. The open reading frame of the long sequence and the short sequence contain 1284bp and 1260bp cDNA, encoding 427 and 419 amino acid sequence, respectively. Sequence analysis revealed that the overall protein sequence and specific functional sites of FcMstn were highly conserved with those in other crustacean species. In the early development stage, the muscle firstly appeared in nauplius stage and developed gradually until post larval, but the expression of FcMstn at mRNA and protein levels decreased from nauplius stage to post larval stage, indicating that Mstn involved in myogenesis as a negative regulator in shrimp. In the adult shrimp, the expression of FcMstn at mRNA and protein levels in muscle were significantly lower in the larger group than in the smaller group, and the diameter and number of muscle fiber of the muscle were significantly different between the two groups. Moreover, the shrimp with reduced level of FcMstn by RNAi displayed a dramatic faster growth rate compared with the control group. The present study demonstrates that FcMstn involved in myogenesis and muscle growth probably also as a negative regulator in shrimp like in vertebrates.

Pathogenicity of a Vibrio owensii strain isolated from Fenneropenaeus chinensis carrying pirAB genes and causing AHPND

An emergent shrimp disease, acute hepatopancreatic necrosis disease (AHPND), has been causing great economic losses to the shrimp farming industry. The original causing agent of AHPND was regarded as Vibrio parahaemolyticus, with a plasmid named pVA1 carrying two Photorhabdus insect-related (Pir) toxin genes pirA and pirB. In the present study, a Vibrio owensii strain named FcYS03 was isolated from the Chinese shrimp Fenneropenaeus chinensis, which caused a high mortality in shrimp with typical AHPND signs. This strain carried the binary toxin genes pirAB and could cause AHPND both in Fenneropenaeus chinensis and Penaeus vannamei (previously named Litopenaeus vannamei). The pathogenicity of FcYS03 to P. vannamei exhibited apparent temperature and salinity dependence. Through genome sequence analysis among FcYS03 and AHPND-causing V. parahaemolyticus strain 3HP, we found that a segmental rearrangement phenomenon existed in the plasmid of FcYS03. The toxin genes pirAB happened to be located at the rearranged segment, and two transposases for transposon Tn903 were distributed at the two ends of the rearranged segment, which indicated that transposon Tn903 might be related to the transfer of the toxin genes among the bacteria. The study will provide valuable information for the understanding and prevention of AHPND in shrimp aquaculture.

Spermiogenic histone transitions and chromatin decondensation in Decapoda

Decapoda are among of the most diverse groups of Crustacea with an important economic value, and have thus been the focus of various reproductive biology studies. Although spermatozoa are morphologically diverse, decapod spermatozoa possess common features, such as being non-motile and having uncondensed nuclear chromatin. Many scholars have studied uncondensed chromatin in decapod spermatozoa; however, the role of biologically regulated decondensation in spermatozoa remains unclear. In this study, histone changes in the spermatozoa of five commercially relevant aquatic crustacean species (Eriocheir sinensis, Scylla paramamosain, Procambarus clarkii, Fenneropenaeus chinensis, and Macrobrachium nipponense) were studied via liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunofluorescence. The LC-MS/MS results confirmed that all four core histones were present in the sperm nuclei of the five Decapoda species. Positive fluorescent signals from histones H2A, H2B, H3, and H4 were detected in the spermatozoa nuclei of E. sinensis, S. paramamosain and M. nipponense via immunofluorescence. Histone H2A was first identified in the membrane sheets or cytoplasm of mature sperm in P. clarkii and F. chinensis, whereas H3 and H4 were generally distributed in the nucleus of the spermatozoa. Histone H2B gradually disappeared during spermiogenesis and was not found in the sperm of P. clarkii and F. chinensis eventually. Our data suggest that core histones are instructive and necessary for chromatin decondensation in decapods spermatozoa. Thus, our results may help resolve the complex sperm histone code and provide a reference for the study of spermatozoa evolution in Decapoda.

Molecular Characterization and Expression Profiling of Three Transformer-2 Splice Isoforms in the Redclaw Crayfish, Cherax quadricarinatus.

Sex determination/sex differentiation is determined by genetics, environmental factors, or the interactions of the two. The Transformer-2 (Tra-2) gene plays an important role in the sex determination cascade signal pathway in insects. In this study, the Tra-2 gene was isolated and characterized from the cDNA library of gonad tissues in the redclaw crayfish, Cherax quadricarinatus. Three splice variants were identified, designated as CqTra-2A, CqTra-2B, and CqTra-2C, and sequence analysis showed that they had a highly conserved RRM domain. Phylogenetic analysis was performed by the NJ method, and the results revealed that the Tra-2 protein of the redclaw crayfish was very closely related to those of Macrobrachium rosenbergii, Fenneropenaeus chinensis, and Macrobrachium nipponense. Real-time PCR analysis showed that the three isoforms were predominantly expressed in the ovary and gradually increased with embryonic development. Additionally, the expression pattern of CqTra-2 at different developmental stages was analyzed by qPCR and revealed that the phase of having a body length of 3 cm may be the key period for the sex differentiation of C. quadricarinatus. RNAi-targeting gene silencing further confirmed the function of CqTra-2 in sexual differentiation in redclaw crayfish. Our experimental data will contribute to understanding the mechanism of sex determination in crustaceans.

A dynamic energy budget model of Fenneropenaeus chinensis with applications for aquaculture and stock enhancement

Dynamic energy budget (DEB) theory provides a framework for quantifying metabolic processes and biological rates. DEB models have been widely applied to aquaculture species, but this type of model has great potential for application to fisheries for stock assessment and enhancement. The shrimp Fenneropenaeus chinensis, widely distributed along the coast of China and Korea, is the most important fisheries and aquaculture species in China. With the AmP method, DEB parameters were estimated for the population along the coast of China. The parameter estimation achieved an overall goodness of fit with MRE of 0.131 and SMSE of 0.178. In comparison with similar species, the values of a few main parameters are relatively high including reserve capacity (Em), somatic maintenance (ṗM) and allocation fraction to growth and somatic maintenance (κ). This may reflect an adaptation to variation of environmental conditions. The model can predict the physiological behaviours including respiration, ammonia excretion and feeding rates reasonably well. It shows overall capability to predict the growth and reproduction with acceptable confidence in three main geographic regions. There are clear differences between the female and male with much faster growth rate of the former. Validations of the model have shown that it can adequately predict growth of the shrimp in both its natural distribution waters and land-based culture systems. This study provides important information for further development of modeling tools which can contribute to estimating the carrying capacity for stock enhancement and optimizing production from integrated multi-trophic aquaculture.

Lipid Profiles in By‐Products and Muscles of Three Shrimp Species (Penaeus monodon, Penaeus vannamei, and Penaeus chinensis)

AbstractTo better understand the health benefits of lipids in shrimp and evaluate their potential value, a comprehensive analysis of lipid profiles in by‐products (head and body carapace) and muscles of shrimps Penaeus monodon, Penaeus vannamei, and Penaeus chinensis is performed. Results show that freeze‐dried muscles of these shrimps contain 3.83%, 4.39%, and 2.93% of lipids, respectively, while the corresponding by‐products contain 4.69%, 5.89%, and 5.39% of lipids, respectively. The total lipids comprise glycerophospholipid (PL, 54.86–77.29%), cholesterol (12.67–18.79%), triacylglycerol (1.28–7.02%), diacylglycerol (0.27–1.58%), monoacylglycerol (0.32–3.04%), and free fatty acid (FFA, 2.84–20.58%). Further, PL contains cholineglycerophospholipid (PLCho, 49.75–66.99 mol%), ethanolamineglycerophospholipid (PLEtn, 14.02–28.16 mol%), serineglycerophospholipid (PLSer, 4.85–12.66 mol%), inositolglycerophospholipid (PLIns, 4.36–15.63 mol%), and cholinelysoglycerophospholipid (LPLCho, 2.07–6.35 mol%). Lipids are abundant in polyunsaturated FA (36.55–42.72% of total FA), among which eicosapentaenoic acid (6.38–11.59% of total FA), and docosahexaenoic acid (7.63–12.08% of total FA) are dominant. About 200 species of PL belonging to PLCho, PLEtn, PLIns, LPLCho, lysoglycerophosphoethanolamine (LPLEtn), and lysoglycerophosphoserine (LPLSer) are characterized. Moreover, the by‐products contain higher amounts of astaxanthin than the muscles. Considering high level of PUFA enriched PL, shrimp by‐products can serve as a source for nutritional lipids.Practical Applications: This study presented a comprehensive analysis of the lipid profiles in by‐products (head and body carapace) and muscles of shrimps Penaeus monodon, Penaeus vannamei, and Penaeus chinensis. The results obtained justified the use of by‐products in shrimp processing, indicating that by‐products can be used for commercial exploitation and production of value‐added products due to PUFA‐enriched PL, especially EPA and DHA.

Qualitative and quantitative detection using eDNA technology: A case study of Fenneropenaeus chinensis in the Bohai Sea

Accurate knowledge of species distributions and population dynamics is the basis for conservation biology. However, for certain species with unique life histories and very small populations, monitoring species distributions and population dynamics is extremely difficult. Recently, newly developed eDNA technology has been widely used in species monitoring, biodiversity assessments, and biomass assessments. In this research, we studied Fenneropenaeus chinensis in the Bohai Sea. We used a 0.45 μm glass fiber filter combined with a vacuum to filter 2 L seawater samples for eDNA enrichment from 54 stations in June and 60 stations in August. A DNeasy Blood and Tissue kit was used to extract the eDNA. After DNA extraction, the specific primers and probes of the mitochondrial DNA COI gene of F.chinensis were designed. Real-time quantitative PCR was used to qualitatively and quantitatively analyze the eDNA in the Bohai Sea. The temporal and spatial distribution of F.chinensis was detected by the eDNA technique. The relationship between the eDNA copy number and trawl-netted F.chinensis biomass was explored. The applicability and sensitivity of eDNA technology in marine crustacean research were verified. The results showed that the mtDNA COI gene of F.chinensis was successfully amplified in the 54 water samples collected in June, and the detection rate reached 100%. Detections occurred in only 23 of the 60 stations sampled in August. F.chinensis had a detection rate of only 38%. The copy number of eDNA obtained by real-time PCR was fitted to the density of F.chinensis captured by bottom trawling. There was not a significant positive correlation between copy number and biomass. The results obtained through this research will provide a method and theoretical basis for the application of eDNA technology in marine crustacean research.

Integrative phenotypic and gene expression data identify myostatin as a muscle growth inhibitor in Chinese shrimp Fenneropenaeus chinensis

Growth traits, largely determined by muscle growth, are the most critical economic traits in shrimp breeding. Myostatin (Mstn) is a conserved inhibitor of muscle growth in vertebrates, but until now solid evidence supporting a similar function of Mstn in invertebrates has been lacking. In the present study, we examined the Mstn expression along with growth trait data in a Fenneropenaeus chinensis population, to establish a potential correlation between Mstn and growth. The heritabilities of FcMstn expression, body weight at 190 days of culture, body weight and length at 230 days of culture, and average daily gain were estimated using 773 individuals and a thirteen-generation pedigree. The results showed FcMstn expression was negatively correlated with the growth traits, and the mean FcMstn expression in females was significantly lower than that of males, indicating Mstn negatively regulates muscle growth in shrimp, and its lower expression may underscore the faster growth of females. Low heritabilities were detected for FcMstn expression, suggesting that the expression of Mstn might be heritable in shrimp. These results provide strong support for a growth inhibitory function of Mstn in F. chinensis, and suggest a potential method for selective breeding of this species without substantial experimental resources and labor force.

IN SILICO CHARACTERISATION AND HOMOLOGY MODELLING OF TOLL/TOLL LIKE RECEPTORS (TLRS) FROM PENAEID SHRIMPS

Toll or Toll-like receptors are conserved receptors, which act as the first line of defense against infection by pathogens. To use Toll/Toll like receptors as drug targets, it is essential to understand their physico-chemical properties and three dimensional structures. In the present study, physico-chemical properties and secondary structure of Toll/Toll like receptors from selected species of penaeid shrimps viz., Penaeus chinensis, P. vannamei, P. monodon and P. japonicus were computed using online servers. Three dimensional structure was predicted by homology modelling using different softwares, SWISS-MODEL, Phyre2 and Geno3D softwares were validated using online tools to find the best model for the protein under study. From the physicochemical properties, nature of the Toll/Toll like receptor protein was revealed as acidic, thermostable, hydrophobic and transmembrane protein. Structural analysis indicated the presence of alpha helices and random coils as predominant elements followed by extended stands and beta turns. Three dimensional structures predicted using SWISS-MODEL was validated as extremely good model using Protein Quality Predictor online server.

The dynamics of bacterial community in a polyculture aquaculture system of Penaeus chinensis , Rhopilema esculenta and Sinonovacula constricta

Polyculture with Chinese shrimp Penaeus chinensis, jellyfish Rhopilema esculenta and razor clam Sinonovacula constricta (S.J.R) is a common aquaculture system in Dandong, China. Investigation on the composition and function of microbial communities and their relationship with environmental factors in aquaculture systems have crucial implications. Therefore, the sequencing of 16S rRNA gene was applied to profile the bacterial community composition of water and sediment in S.J.R polyculture system in the present study. Proteobacteria was the dominant phylum in S.J.R polyculture ponds following with Actinobacteria and Bacteroidetes in water; in contrast, more diverse phyla were detected in sediments. Water temperature, pH and dissolved oxygen were determined the bacterial community composition in the S.J.R polyculture systems. Specially, Planktomarina, PS1 clade, Candidatus Aquiluna and Fibrobacteres, which can resist the phytoplankton blooms or degrade the cellulose, were more abundant in water at the early stage of cultivation in the S.J.R polyculture system. Moreover, the functions of bacterial communities in water were mainly associated with cell communication mediated, while the functions related to basal metabolism were enriched in sediments. The findings of this study allowed us to better understand the bacterial community in the S.J.R polyculture system and accumulated data for the improvement of cultural management.

Genetic diversity status and conservation priority of hatchery-produced offspring populations of Fenneropenaeus chinensis by microsatellite DNA

The Chinese shrimp Fenneropenaeus chinensis is an important economic species in China. To evaluate the genetic diversity of hatchery-produced offspring of F. chinensis, 15 populations were collected from three provinces in China and analysed using nine microsatellite DNA loci. High values for expected and observed heterozygosity (He and Ho respectively), as well as for polymorphism information content (PIC), were obtained (He=0.845–0.905, Ho=0.507–0.766, PIC=0.834–0.891), and no loss of genetic variability was detected in F. chinensis in this study. The genetic differentiation among 15 populations was small, suggesting genetic homogeneity among hatchery-produced offspring. The results of the present study indicate that the most immediate and effective conservation priority for F. chinensis in Chinese coastal waters should be maintaining the current genetic diversity. Genetic monitoring should be performed to maintain an effective population size and avoid loss of genetic diversity.

Comprehensive expression analysis of the beta integrin from Penaeus monodon indicating its participation in innate immunity and ammonia nitrogen stress response

The aim of the present study was to investigate the function of the beta integrin (PmItgb) in Penaeus monodon. The 3011 bp cDNA sequence of PmItgb was cloned from P. monodon using rapid amplification of cDNA ends (RACE) PCR. Phylogenetic tree analyses indicated that the amino acid sequence of PmItgb should be merged into Fenneropenaeus chinensis (93%). Quantitative real-time PCR (q RT-PCR) revealed that PmItgb mRNA was highly expressed in the hemocytes. In addition, with regard to developmental stages, PmItgb showed significantly higher expression in oosperm, nauplius IV, zoea I and III, and post larval stages than that in other development stages. PmItgb expression in the shrimp epidermis was higher in the postmolt (B) stage, and lower in other molting stages. We also found that Vibrio harveyi and V. anguillarum challenge enhanced PmItgb expression in the hepatopancreas and gills. When PmItgb was inhibited, innate immunity-related genes such as ALF, crustin 1, crustin 7, penaeidin 3, and penaeidin 5 were significantly down-regulated. Furthermore, we demonstrated that PmItgb knock-down by specific dsRNA reduced bacterial clearance. In high ammonia nitrogen concentrations, PmItgb was significantly up-regulated in the hepatopancreas and gills. After PmItgb was silenced, the rate of mortality owing to high ammonia nitrogen concentrations decreased; the expression of related anti-apoptotic genes was up-regulated, and that of the apoptotic genes was slightly down-regulated. These results suggested that PmItgb may be involved in shrimp innate immunity and mediate apoptosis of hepatopancreatic cells induced by high ammonia nitrogen environments.

Conjoint Analysis of SMRT- and Illumina-Based RNA-Sequencing Data of Fenneropenaeus chinensis Provides Insight Into Sex-Biased Expression Genes Involved in Sexual Dimorphism.

Fenneropenaeus chinensis (F. chinensis) is one of the most commercially important cultured shrimps in China. The adult F. chinensis exhibit sexual dimorphism in growth and body color. In this research, we profiled the whole transcriptome of F. chinensis by using single molecule real-time-based full-length transcriptome sequencing. We further performed Illumina-based short reads RNA-seq on muscle and gonad of two sexes to detect the sex-biased expression genes. In muscle, we observed significantly more female-biased transcripts. With the differentially expressed transcripts (DETs) in muscle, some pathways related to the energy metabolism were enriched, which may be responsible for the difference of growth. We also digged out a pathway named porphyrin and chlorophyll metabolism. It was speculated to relevant to the difference of body color between the two sexes of shrimp. Interestingly, almost all DETs in these pathways were female-biased expression in muscle, which could explain the phenomenon of better growth performance and darker body color in female. In gonad, several pathways involved in reproduction were enriched. For instance, some female-biased DETs participated in the arachidonic acid metabolism, which was reported crucial in female reproduction. In conclusion, our studies identified abundant sex-biased expression transcripts and important pathways involved in sexual dimorphism by using the RNA-seq method. It provided a basis for future researches on the sexual dimorphism of F. chinensis.

Genetic evaluation of Chinese shrimp (Fenneropenaeus chinensis) stock enhancement in the Yellow Sea and Bohai Sea based on mitochondrial DNA control region

Stock enhancement is a fishery management approach involving the release of hatchery organisms to increase the abundance of natural fish or invertebrate population. In this study, genetic evaluation of Fenneropenaeus chinensis stock enhancement was carried out based on the mitochondrial DNA control region. The haplotype diversity (Hd) and nucleotide diversity (π) of broodstock populations were generally higher than that of recaptured populations. The molecular variance analysis (AMOVA) results demonstrated that genetic variance was in connection with the time of releasing and recapture. A significant pairwise FST value was only obtained between L1CY and C2LZ. But there was no obvious correlation between their geographical distance and genetic difference, confirming that time factor might be the leading cause of differences. Haplotypes shared by more than three individuals all could be recaptured, which indicated that the enhancement experiment was relatively successful. In general, the enhancement effect in 2012 was better than that of in 2013.

Niches and interspecific association of dominant shrimp species in the offshore waters of southern Zhejiang Province, China

Based on data from November of 2015 (autumn), February (winter), May (spring), and August (summer) of 2016 in the offshore waters of southern Zhejiang Province, the relationships between major shrimps species were examined by niche breadth, niche overlap, variance ratio, chi-square test, association coefficient and species pair co-occurrence percentage. The results showed that temporal niche breadth of Atypopenaeus stenodactylu was the largest, spatial niche breadth of Solenocera crassicornis was the largest, and A. stenodactylu had the largest spatio-temporal niche breadth. The temporal niche overlap between Parapenaeus fissuroides and Parapenaeopsis tenella was the highest. The spatial niche overlap between Solenocera koelbeli and Penaeus chinensis, P. fissuroides and Heterocarpoides laevicarina were the highest. The spatio-temporal niche overlap between S. koelbeli and P. chinensis was the highest. The analysis of variance ratio showed that the main shrimp species were significantly positively correlated. Positive correlation existed in 13 pairs (χ2≥3.841). Results from the association coefficient (AC) and co-occurrence percentage (PC) indicated that the interspecific association tended to be positive. Our results provide supports for exploring niche breadth and niche overlap of major shrimp species and improving niche differentiation.

Evaluation of metal pollution-induced biological effects in Chinese shrimp Fenneropenaeus chinensis by NMR-based metabolomics

Metal pollution in Laizhou Bay along the Bohai Sea in China has been posing a risk on fishery species and hence may affect seafood quality. In this work, shrimps Fenneropenaeus chinensis were sampled from three sites, namely, a reference (site 6334) and two metal-polluted (sites 6262 and 7262) sites, located in Laizhou Bay. The metal concentrations in shrimp muscle tissues were tested using the ICP-MS technique. The Cr and Cu concentrations were the highest in the shrimp samples from site 7262, exceeding the national seafood safety standard Ⅱ, and the As concentration was much higher than the national seafood safety standard Ⅲ. NMR-based metabolomics indicated that metal pollution induced oxidative and immune stresses, damaged the muscular structure, and disrupted energy metabolism in shrimps at sites 6262 and 7262, in particular disturbed osmotic regulation in shrimps at site 7262. Glycine and serine could serve as biomarkers for Cd in F. chinensis.

Effect of white spot syndrome virus infection on a Ras gene in the Chinese shrimp Fenneropenaeus chinensis

Ras is a small GTP-binding protein that is involved in the regulation of diverse cellular processes, including cell cycle progression, proliferation, and apoptosis. In the present study, a cDNA encoding Ras protein in Chinese shrimp Fenneropenaeus chinensis (designated FcRas) was cloned. The cDNA of FcRas contained a 564 bp open reading frame (ORF), five conserved regions involved in GTP metabolism, and a CAAX motif. Multiple sequence alignment showed that the C-terminal of Ras was less conserved than the N-terminal. In healthy F. chinensis, the FcRas mRNA level in the hepatopancreas and gill were both significantly (P < 0.05) higher than the level in muscle. Following challenge with white spot syndrome virus (WSSV), the FcRas mRNA level in the muscle was significantly (P < 0.05) upregulated at 48 h post-infection (hpi). In the hepatopancreas, the FcRas mRNA level was significantly downregulated at 12 hpi (P < 0.01) and 24 hpi (P < 0.05). The protein level of FcRas in the hepatopancreas was significantly downregulated at 6, 12, 24, and 48 hpi (P < 0.05). These results suggested that the FcRas expression level was influenced by WSSV infection.

Trophic ecology of Penaeus chinensis (Decapoda: Dendrobranchiata: Penaeidae) and potential competitive interactions with other species in the Haizhou Bay determined by carbon and nitrogen stable isotope analysis

The Chinese white shrimp Penaeus chinensis is one of the most economically important crustacean species in China with respects to both capture and aquaculture. Stable carbon and nitrogen isotope ratios (δ13C and δ15N) was analyzed to reveal its potential dietary characteristics, in particular contributions of primary producers as food sources, as well as isotopic niche width and potential food competitions with materials from Haizhou Bay in Yellow Sea, a state-level germplasm source conservation and stock recovery area. The results confirmed that bivalves served as an important diet of P.chinensis and the prawn incorporated a mixture of benthic microalgae and marine phytoplankton as food sources, while terrestrial organic matter supposed to be made minimum contributions. Benthic microalgae overwhelmingly dominated in the dietary proportion (mode), and accounted for 90% of the food sources in comparison with the contribution of 10% of marine phytoplankton. Penaeus chinensis was closest to Charybdis japonica and Dorippe japonica in isotopic compositions. Trophic niche widths were similar in P.chinensis and D. japonica, and they were larger than that of C.japonica, as determined by the sizes of SEAb (Bayesian standard ellipse areas). The overlaps of standard ellipse areas of P.chinensis with C. japonica and D. japonica were 98.5% and 86.5% respectively, indicating intense competition for food between P.chinensis and the other two species. In the views of food availability and competition, biomasses of benthic microalgae, bivalves and C.japonica and D.japonica may regulate the population of P.chinensis in Haizhou Bay.

Antioxidant responses of Fenneropenaeus chinensis to white spot syndrome virus challenge

In order to gain insights into the responsive characteristics of the antioxidant systems of shrimp during viral infection, in the present study, Fenneropenaeus chinensis “vaccinated” with inactivated white spot syndrome virus (WSSV) and the control were challenged by WSSV, then total antioxidant capacity (T-AOC) and the activities of 4 antioxidant enzymes in the hepatopancreas, stomach, gills, plasma, and hemocytes were examined and compared. The results showed that after WSSV challenge, T-AOC and the activities of the antioxidant enzymes in all the tested tissues of the “vaccinated” shrimp kept increasing for a longer time and reached significantly higher values (p < 0.05); the survival rates of this group remained higher too (p < 0.05); furthermore, the values of the same parameters varied in different tissues, indicating tissue-specific responses of the antioxidant systems. This study revealed that “vaccination” should account for enhanced antioxidant responses, which were somewhat pathogen-specific but well coordinated in shrimp protection; it will also be helpful for further exploring the action mechanisms of antioxidant systems in the shrimp immunity.