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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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In Press  doi: 10.11964/jfc.20180111146
[Abstract](15) [FullText HTML](6) [PDF 2026KB](2)
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Manganese superoxide dismutase (MnSOD), a transition-metal-containing antioxidant enzyme that dismutates the superoxide radicals to either ordinary molecular oxygen (O2) or hydrogen peroxide (H2O2), widely existed in many aerobic organisms. In this study, the cDNA of MnSOD, identified from Nibea albiflora, was 958 bp in length including 5′-untranslated region (UTR) of 47 bp, 3′-UTR of 233 bp and an open reading frame (ORF) of 678 bp encoding a polypeptide of 225 amino acids. The deduced amino acid sequence analysis showed that MnSOD contains a putative signal peptide in the N-terminus (1-27 aa), four Mn binding sites (His 53, 101, 190 and Asp 186) and a Mn/Fe SOD signature sequence (186-193 aa). Phylogenetic tree analysis indicated that N. albiflora has the closest relationship with Larimichthys crocea, and was classifie into the same cluster with other teleosts (Epinephelus coioides, Takifugu fasciatus, Paralichthys olivaceus, Danio rerio and Anguilla japonica). Quantitative real-time qRT-PCR analysis showed that the mRNA transcripts of MnSOD were detected in all examined tissues and the predominant distribution was in heart, followed by brain, liver, gill, kidney, intestine, stomach, head-kidney, muscle and swim bladder, and the minimum level was displayed in spleen. Moreover, during the acute toxic experiment of ammonia nitrogen or nitrite nitrogen, N. albiflora showed more sensitive to ammonia nitrogen, and the 96 h median lethal concentration (LC50) value was found to be 20.23 mg/L for ammonia nitrogen (or 0.57 mg/L for non-ionic ammonia) with safe concentration (SC) values of 2.02 mg/L (or 0.06 mg/L for non-ionic ammonia) and 99.08 mg/L with SC of 9.91 mg/L for nitrite nitrogen, successively. Furthermore, the temporal expression of MnSOD was significantly up-regulated in the liver, gill and head-kidney of N. albiflora. The expression features of the MnSOD suggested its important role in scavenging oxygen free radicals caused by ammonia nitrogen/nitrite nitrogen and could be used as an early biomarker for detection of environmental pollution.
In Press  doi: 10.11964/jfc.20180711345
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To isolate and identify lytic bacteriophages against AHPND-associated Vibrio parahaemolyticus and analyze their biological properties. Lytic bacteriophages were isolated from Fujian and Mexico seawater samples by double-layer agar culture method, and one strain of V. parahaemolyticus strain associated with AHPND was used as the host bacterial strain for phage isolation and amplification. The phages were classified and identified by plaque shapes, restriction endonucleases, whole genome sequence, phylogenetic tree building and transmission electron microscopic technique. The lysis range and biological properties including optimal multiplicity of infection (MOI), thermal stability, pH stability, stability to peracetic acid and survival stability under different temperature were determined. The results showed that 3 lytic bacteriophages against AHPND-related V. parahaemolyticus were isolated, named as P46, P48 and VP7. P46, P48 and VP7 of which the bacteriophage plaques were translucent circle. The plaque diameter of P46 was 4~5 nm. The plaque diameter of P48 and VP7 were 5~6 mm. The nucleotides of 3 bacteriophages were all dsDNA. P46, P48 and VP7 all had an icosahedral head with about 60 nm diameter. Their tails were about 18~20 nm length and 8 nm width. 3 phages were belonged to the familiy Podoviridae. The cocktail of P46, P48 and VP7 infected 91.5% of AHPND-associated V. parahaemolyticus strains and non-VPAHPND 92.3% respectively. And they all could not identify non-V. parahaemolyticus bacteria. The optimal MOI of P46, P48 and VP7 were 0.001、0.1 and 0.001 respectively. The optimal pH of P46 and VP7 were 6~8 and P48`s was 6~9. Three bacteriophages were stable at 60 °C and had higher survival rate at 4 °C after 50 weeks. P46, P48 and VP7 also tolerated peracetic acid with universal bactericidal concentration. Alignment with the sequences of the conserved protein sequences of NCBI showed that P46, P48 and VP7 had low homology with other bacteriophages. Bacteriophages P46, P48 and VP7 might be 3 novel Podoviridae bacteriophages. This study is the first report of lytic Podoviridae bacteriophages against AHPND-associated V. parahaemolyticus in China. The reuslts enrich the resources of bacteriophages against AHPND-associated V. parahaemolyticus and provide potential application of phages as a biocontrol agent.
In Press  doi: 10.11964/jfc.20180811404
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To compare the differences in gut microbiota and antibiotic resistance genes (ARGs) between Penaeus Vannamei and Macrobrachium rosenbergii. Microbiota community structure and microbiota diversity of two shrimps were analyzed by high-throughput sequencing and Denaturing Gradient Gel Electrophoresis (DGGE), and 38 kinds of ARGs in the gut bacteria of two shrimps was detected. The effective bacterial sequences of P. vannamei and M. rosenbergii were 42 795 and 40 713. The results showed that the number of Operational taxonomic units (OTUs) were 124 and 82, and the bacterial types with clear classification status were 5 phyla 17 genera and 5 phyla 16 genera. The dominant group in the gut bacteria of P. vannamei is Proteobacteria, which accounts for 75.45%. The dominant species are Paracoccus (25.83%) and Acinetobacter (25.24%). The dominant group in gut bacteria of M. rosenbergii is Firmicutes (49.74%), and the dominant species are Lactococcus (49.01%) and Vibrio (29.98%). The Shannon index of the gut bacteria (2.19) of P. vannamei was higher than that of the M. rosenbergii (1.78), indicating that the gut bacteria diversity of the former was greater than that of the latter. The analysis results of DGGE fingerprint were similar to those of high-throughput sequencing, and the bacterial diversity of the two shrimps was significantly different. The PCR results showed that the gut bacteria of P. vannamei carried 15 ARGs and gut bacteria of M. rosenbergii carried 14 ARGs. Our study revealed that the community diversity, OTU richness, total number of species and ARGs in the gut bacteria of P. vannamei were higher than those of M. rosenbergii, which provided a theoretical basis for the subsequent excavation of gut microbial resources.
In Press  doi: 10.11964/jfc.20180111155
[Abstract](10) [FullText HTML](5) [PDF 1016KB](0)
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With the development of aquaculture, far more attention has been paid to safety in fish drugs usage. In order to find alternatives to antibiotics, silver nanoparticles (AgNPs) were synthesized using extracts of Ginkgo leaves with AgNO3 in this study. The synthesized silver nanoparticles were characterized by UV-Visible spectrophotometer, transmission electron microscope and X ray diffraction spectrum. The antibacterial efficacy was assessed against Staphylococcus aurous, Escherichia coli and common bacterial pathogens in aquacuture including Edwardsiella tarda and Aeromonas hydrophila, by using cylinder plate method, broth macrodilution method and bacteriostasis kinetic experiments. The results showed that the absorbance maximum was observed at 460 nm corresponding to the plasmon absorbance of the AgNPs. Transmission electron microscope revealed that the AgNPs had an average size below 10 nm.The X-Ray Diffraction (XRD) spectrum of the nanoparticles confirmed the formation of metallic silver.The AgNPs synthesised in this research exhibited good antibacterial efficacy against the test pathogens. This investigation demonstrated that the green syn thesis of AgNps with leaves of Ginkgo biloba was not only fast and convenient but also cost effective and ecofriendly, which has good prospects in control of aquaculture diseases.
In Press  doi: 10.11964/jfc.20180511293
[Abstract](6) [FullText HTML](2) [PDF 843KB](0)
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Fish skin mucus serves as the first line of defense against pathogens and external stressors. The mudskipper Boleophthalmus pectinirostris inhabit intertidal mudflats containing abundant and diverse microbial population, thus, the skin together with the mucus of B. pectinirostris are very important for the immune defense, osmotic pressure maintenance and adaptation to amphibian life. For exploring the proteomic profile of the skin mucus and understanding the molecular mechanism of B. pectinirostris adaption to amphibious environments, the antibacterial activity was determined by agar diffusion plate method for the mucus and the serum samples. In addition, a growth curve inhibition method was used to compare the antibacterial activities of B. pectinirostris mucus before and after vibrio induction. Furthermore, the proteomic profile of natural B. pectinirostris mucus was identified by shotgun mass spectrometry technology combining with skin transcriptome searching. The interaction network analysis of the identified proteins from mucus were performed by Strin software. Skin mucus was collected from B. pectinirostris after electrical stimulation. The mucus of B. pectinirostris showed a broad spectrum of antimicrobial activity more than serum of the same species, indicating that the mucus has a stronger antimicrobial activity than the serum. After vibrio induction, the antibacterial activity of mucus showed slightly stronger for some gram-negative bacteria than that of un-induced mucus. A total of 97 proteins were identified from natural mucus of B. pectinirostris with a similar results from studies of other fish species, including actins, keratins, apolipoproteins, transferrins, calmodulins, ubiquitins, pentraxins, and various enzymes. However, some proteins, such as ubiquitin-like proteins and thymosin, were identified firstly from fish mucus. The identified proteins can be clustered into structural proteins, enzymes, material transport related proteins, immune proteins, and other proteins. Most of these proteins are known to be involved in immune and/or stress responses. Protein interaction analysis showed strong interactions among the identified proteins, such as actin, myosin, cofilin, filamin, apolipoprotein, transferrin, calmodulin, and superoxide dismutase. The proteomic profile established in this study could not only contributes knowledge on the routes involved in mucosal innate immunity, but also establishes a non-invasive technique based on locating immune markers with a potential use for prevention and/or diagnosis of fish diseases.
In Press  doi: 10.11964/jfc.20180411227
[Abstract](5) [FullText HTML](2) [PDF 807KB](0)
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In order to investigate the difference of the intestinal community structure and its relationship with environmental factors in response to disease, the intestine of healthy and diseased Tranchinotus ovatus was to analyze the bacterial community composition and diversity as well as the culture water and pellet feed. The five samples were carried out by using Illumina HiSeq high-throughput sequencing and biological information analysis method. Compared with the intestinal microflora of the healthy ovatus, the relative abundances of Spirochaetes significantly increased in the diseased ovatus, whereas, the Firmicutes and Bacteroidetes exhibited an opposite pattern. The bacteria species in diseased ovatus intestine only accounted for 54.94% in healthy ovatus. There was 73.46% of the OTUs in the healthy ovate intestine the same as that in the culture water, and 70.58% in the feed, while the percentage dropped to 17.98% and 38.95% in the diseased ovate. Notable, the disease ovatus had a higher relative abundance of Vibrio ponticus than healthy ovatus being 78.90% and 17.19%, respectively. In addition, the relative abundance of Photobacterium leiognathi in healthy ovatus was 54.53% but absented in diseased ovatus. The intestinal bacterial composition was relatively stable but still some difference between healthy and diseased ovatus. After the occurrence of disease, the bacterial diversity declined markedly. The culture water and feed had a close correlation with the healthy ovatus intestine but low influence on diseased ovatus in bacterial species composition.
In Press  doi: 10.11964/jfc.20190211670
[Abstract](3) [FullText HTML](1) [PDF 555KB](0)
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Modern marine ranching is a new type of achieving marine environmental protection and efficient production of fishery resources, which is of great significance in accelerating the shift in driving forces for economic development. We illustrated the development history of modern marine ranching concept, the history and current situation of modern marine ranching construction, and proposed strategic concept to promote the sustainable development of China’s modern marine ranching from the perspectives of innovation drive, technology leader and project demonstration. This review aims to provide reference for the upgrading and transformation of China’s marine fishery.
In Press  doi: 10.11964/jfc.20180511272
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Giant freshwater prawn (Macrobrachium rosenbergii) is an important cultured species in China. Molting is closely related to the growth and breeding of M. rosenbergii. Chitinase, a member of the glycoside hydrolase family 18, plays vital physiological roles in crustaceans, including molting, digestion, and immunity. The molting cycle of M. rosenbergii consisted of five stages, named postmolt Ⅰ (A), postmolt Ⅱ (B), intermolt (C), premolt (D), and molt (E). To understand the characteristics and molecular dynamics of chitinase in the molting cycle of M. rosenbergii, the chitinase gene of M. rosenbergii (MrChi3B) was cloned. Thereafter, polyclonal antibody against the chitinase was generated in rabbit. The cDNA of MrChi3B spans 1 143 bp that encodes a protein of 380 amino acids (aa) with a predicted molecular weight of 41.91 ku. Phylogenetic analysis revealed that chitinase contains the GH18 family catalytic domain, and it was closely related to chitinase of M. nipponense with 94% homology at the aa level. The expression profile of MrChi3B in six different tissues (eyestalk, gill, stomach, muscles, endocuticle, intestine) and at different stages of the molting of M. rosenbergii was investigated by quantitative real-time PCR (qRT-PCR) and Western blot (WB) analysis. The results showed that the MrChi3B was ubiquitously expressed in all the tested tissues, whereas its expression was significantly increased in stomach, skin, and muscle at A, B stages. At the stage C, highest expression of MrChi3B was observed in the stomach. At the stages A, B, the expression of MrChi3B in the endocuticle and muscle reached the highest. The expression of MrChi3B in the intestine has increased during the stage D and E. Relative lower expression of MrChi3B was observed in the eyestalk at all the stages. The results will shed a new light on the further study of the function of MrChi3B from M. rosenbergii.
In Press  doi: 10.11964/jfc.20180411232
[Abstract](10) [FullText HTML](5) [PDF 852KB](0)
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The objective of this study was to assess the optimal dietary lipid requirement of advanced genetically improved farmed tilapia (GIFT Oreochromis niloticus), reared at 34 °C water temperature. In present study, 360 fish with average initial body weight of (50.88±1.57) g were randomly divided into 6 groups with 3 replicates of 20 fish in each replicate. Fish in each group were hand-fed a purified diets containing different lipid levels [0.22% (control group), 2.83%, 4.98%, 7.45%, 9.23% and 12.47%] reared at 34 °C water temperature for 56 days. At the end of feeding trial, growth performance, body composition, serum biochemical indexes and the activities of lipid metabolism enzyme in liver were measured. The results showed as follows: with the increase of lipid levels, weight gain rate (WGR), specific growth rate (SGR), protein efficiency rate (PER) and protein retention rate (PRR) of GIFT were increased at first and then decreased, but feed conversion ratio (FCR) and the feeding intake rate (FIR) presented the opposite trend. The highest hepatosomatic index (HSI) was in 12.47% diet group, the other groups were not significantly different in HSI. During the feeding trial, no fish died. Increasing dietary lipid levels contributed to increased whole body and muscle lipid levels. With dietary lipids levels increased (i.e., from 2.83% to 9.23%), liver crude lipid concentrations were significantly lower than that in the control group. Serum triacylglycerol (TG) and total cholesterol (TCHO) levels tended to increase first then decrease with increasing dietary lipids level. Meanwhile, lipoprotein lipase (LPL) and hepatic lipase activities increased as the level of lipid increased, and were highest in 12.47% diet group; hepatic lipase (HL) activities tended to first increase and then to decrease as the level of dietary lipid increased, and was highest in 2.83% diet group. Regression analysis showed the optimum dietary lipid level for maximum WGR and PER was 4.92% and 5.67%, respectively, and for the lowest FCR was 6.49% when GIFT reared at 34 °C water temperature.
In Press  doi: 10.11964/jfc.20171211095
[Abstract](24) [FullText HTML](6) [PDF 586KB](0)
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The Chinese mitten crab (Eriocheir sinensis) is an important aquaculture species and food source in Eastern Asia. At the present, pond-reared broodstock are used for seed production of E. sinensis, and the reasonable utilization of wild-caught broodstock is conducive breeding and selection of E. sinensis. Reproductive performance is one of the most important indicators for the evaluation of broodstock quality in aquatic animals. This study was designed to determine and compare the reproductive performance, egg quality, colouration, proximate and fatty acid composition of wild-caught and pond-reared E. sinensis broodstock. The results showed that: ①the wild-caught E. sinensis broodstock had the slightly higher egg production, fecundity and reproductive effort than the pond-reared females, but there was no significant difference between two treatments. The egg diameter, wet weight and dry weight of individual egg were similar between two treatments. ② The eggs from pond-reared E. sinensis broodstock had significantly higher redness (a*), yellowness (b*) and total carotenoids contents than those of the eggs produced by the wild-caught broodstock, however, there are no significant differences for lightness (L*) and colour difference (dE*). ③ As for proximate composition of eggs, no significant differences were found for the moisture, total protein and total lipid contents between the wild-caught and pond-reared treatments. The eggs from wild-caught broodstock had the significantly higher percentages of C18∶1n9, C18∶1n7, C20∶4n6, C22∶5n3 and C22∶6n3 than the eggs produced by the pond-reared broodstock, but the C18∶2n6 and C18∶3n3 of the wild caught broodstock were significantly lower than those of the pond-reared broodstock. In conclusion, these results indicated that the reproductive performance and egg proximate composition were similar between wild-caught broodstock and pond-reared broodstock with similar body weight, but significant differences were found on redness (a*), yellowness (b*), total carotenoids content and fatty acid composition in the eggs. These results could provide valuable information for the broodstock selection, evaluation of reproductive performance and artificial breeding of E. sinensis in the future.
In Press  doi: 10.11964/jfc.20180211186
[Abstract](12) [FullText HTML](5) [PDF 872KB](0)
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The purpose of this experiment was to investigate the effect of low-fishmeal diet with Bacillus subtilis on growth performance, digestive enzyme activity, antioxidant enzyme activity and its mRNA expression of juveniles Epinephelus lanceolatu♂×E. fuscoguttatus♀. A total of 720 grouper with average initial weight of (7.00±0.02) g were randomly assigned into 8 groups in triplicates with 30 individuals per replicate. Eight diets were prepared by adding 0 (normal fishmeal control group), 0 (low fishmeal control group), 0.10%, 0.25%, 0.50%, 0.75%, 1.00% and 1.25% Bacillus subtilis in a diet with low fishmeal (15%), and were formulated by an optimum fishmeal group (35%) as positive control group. The results showed that there was no significant difference in survival rate (SR) among all the treatments. The weight gain rate (WGR) and specific growth rate (SGR) were increased firstly and then decreased with the B. subtilis level increasing. The feed conversation ratio (FCR) in 0.75% group has the lowest value, while the protein efficiency ratio (PER) showed the opposite trend compared to FCR. The activities of trypsin (TRY) and amylase (AMY) firstly increased and then decreased. The activities of serum catalase (CAT) and superoxide dismutase (SOD) in 0.75% group has the maximum value. The highest CAT and glutathione reductase (GR) mRNA expression in liver of fish were observed in 0.5% and 0.75% group, respectively. Grouper were challenged by Vibrio harveyi for the next 7 days, the survival rate of grouper increased significantly with the B. subtilis level increasing. It can be concluded that the supplementation of 0.63% B. subtilis (1.0×108 cfu/mL) can significantly enhance the growth performance, disease resistance, digestive enzymes, serum CAT and SOD activity and mRNA expression related to immunity of grouper, which is estimated with WGR as the evaluation index.
In Press  doi: 10.11964/jfc.20180511288
[Abstract](11) [FullText HTML](7) [PDF 946KB](0)
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To study the effects of culture temperature on antioxidant capacity and inflammatory responses of Larimichthys crocea macrophages, macrophages were isolated from head kidney of L. crocea and resultant monolayer was maintained at 16 °C, 22 °C and 28 °C, respectively. After adding 25 μg/mL LPS medium to macrophage monolayer for 2 h, cell viability, respiratory burst activity, antioxidant enzyme activities and gene expressions together with IL-1β and Hsp70 mRNA expressions of macrophage cultured at different temperatures were evaluated. Results showed that cell viability of macrophages placed at 16 °C and 22 °C was significantly higher than cells cultured at 28 °C after incubation for 36 h. LPS could significantly promote the respiratory burst activity and inhibited the activities of SOD and CAT enzymes. Macrophage incubated at high temperature (28 °C) showed significantly higher CAT enzyme activity and gene expression, whereas no significant difference was found in SOD enzyme activity and gene expression. LPS triggered potent pro-inflammatory response with IL-1β being the indicative parameter, which was inhibited by high culture temperature. However, transcript levels of Nrf2 and Hsp70 increased with the rise of temperature to a significant extent, and both gene expressions were markedly enhanced by LPS compared to control groups. Taken together, all the results in the present study indicated that temperature may regulate the antioxidant capacity and inflammatory responses of LPS-induced macrophages from head kidney of L. crocea through pathways involving Nrf2 and Hsp70.
In Press  doi: 10.11964/jfc.20180111163
[Abstract](12) [FullText HTML](6) [PDF 1222KB](0)
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To compare microbial community structure, diversity and metabolic potential, and analyze their relationships with the spoilage characteristic between Scomber japonicus and Larimichthys crocea, Illumina MiSeq sequencing technology was used to sequence the 16S rRNA V3-V4 hypervariable region of bacteria, and the physicochemical and microbiological indices including pH, total volatile basic nitrogen (TVB-N), histamine and aerobic plate count (APC) were detected. The correlation between microbes and fish spoilage and histamine producing was investigated by Pearson analysis, and the relationship between bacterial community composition and metabolic function was also predicted by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt). The results showed that the pH, TVB-N, histamine content and APC in both fish fillets increased with the storage time extention, however their values in S. japonicus fillet increased faster and kept higher than those in L. crocea throughout storage. TVB-N and histamine content reached 76.34 mg/100 g, 59.92 mg/100 g in S. japonicus, while 59.98 mg/100 g, 3.11 mg/100 g in L. crocea at the end of storage, respectively. An increase tendency was observed in richness and diversity of bacteria in S. japonicus muscle and then followed by a decrease during the storage, while a sustained increase tendency was observed in that of L. crocea. Shewanella was the dominant bacteria in fillets of both S. japonicus and L. crocea. Twelve types of bacteria in S. japonicus were screened as TVB-N correlation bacteria, ten of which also showed significant correlation with the histamine producing, meanwhile seven types of bacteria in L. crocea were screened as TVB-N correlation bacteria, however, no bacterium showed correlation with histamine producing. Amino acid metabolism and carbohydrate metabolism were higher than other metabolism during the storage. The abundance of function genes related to amino acids metabolism and carbohydrate metabolism in S. japonicus was enormously higher than that in L. crocea throughout the storage period such as histidine, arginine and proline metabolism and butanoate metabolism, propanoate metabolism and pyruvate metabolism, respectively. This may partially explain why S. japonicus was more perishable than L. crocea from the level of metabolism of the bacterial community. Our study provided a new method to understand the spoilage characteristics of different aquatic products from the perspective of bacterial community and their metabolism related function genes.
In Press  doi: 10.11964/jfc.20180711348
[Abstract](3) [FullText HTML](1) [PDF 924KB](0)
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In this experiment, two strains of probiotics, i.e. Enterobacter hormaechei (E3) and Lactobacillus (R3) were used to feed Litopenaeus vannamei for 4 weeks. The diversity of intestinal microflora of L. vannamei in experimental group and blank group was compared and analyzed by Biolog-ECO method in the later period of feeding, in order to evaluate the effect of probiotics on the metabolic function of intestinal microflora of L. vannamei. The results showed that AWCD in the experimental group was significantly higher than that in the blank group, indicating that probiotics enhanced the intestinal microbial activity; the ability of intestinal microorganisms to utilize carbon source was significantly enhanced, which indicated that the digestive enzyme secreted by probiotics increased the digestibility and absorption rate of prawn feed, thus promoting the rapid growth of L. vannamei. There were significant differences in intestinal microbial diversity index (including Shannon, Simpson and McIntosh indexes), which indicated that different strains had different effects on intestinal microflora richness of L. vannamei. The results of sampling on the 1st and 5th day after stopping adding E. hormaechei showed that Shannon index decreased significantly and Simpson index and McIntosh index increased significantly, and lactic acid bacteria was stopped from adding. The results of sampling on the 1st and 5th day showed that there was no significant difference in Shannon index and McIntosh index, but there was no significant difference between them on the 10th day. The results showed that the addition of probiotics to the feed could change the number and structure of the original microflora in the intestinal tract of L. vannamei and promote the complex interaction between the microbial communities in the intestinal tract of L. vannamei. In turn, it plays an important role in maintaining or promoting the health of L. vannamei. It also showed that the two probiotics should stay in the intestines of aquatic animals for at least 5 days.
In Press  doi: 10.11964/jfc.20171111020
[Abstract](8) [FullText HTML](3) [PDF 763KB](0)
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In order to study more about the molecular mechanism of nacre formation, we cloned a novel shell matrix protein hic9 (Accession No. MF508725) from freshwater mussel Hyriopsis cumingii. We analyzed the gene expression by RT-PCR and in situ hybridization.The result indicated that hic9 was expressed most highly in adductor muscle and mantle, and the strong signals occurred in the whole outer epithelial cells of outer fold, and also occurred in the crust groove between out fold and middle fold. This result indicated that hic9 is a multifunctional matrix protein involved in the cuticle, prism layer and nacre layer of the shell. The amino acid sequence of hic9 featured high proportion of Gly (14.81%)、Pro (13.58%) and Ala (12.35%) residues, and formed the "Gly-X-X" structure in the middle of the sequence (X is any amino acid). And there is the continuous repetitive structure of alanine (polyA) structure close to the C terminal of the sequence, together giving the sequence of hic9 similar characters of spider silk protein. The Hic9 C terminus is composed of a hydrophobic sequence, "LAWMLFV", and this sequence is presumed to form a beta folding structure. Next to this sequence, the 89–91 bit is the "Asp-Leu-Asp" sequence, which is a typical Ca2+ binding site.In addition, the expression of hic9 in primary pearl sac was detected by real-time quantitative PCR in the early stage of pearl formation. Expression levels of hic9 in the pearl sac during 3–15 days after implantation maintained roughly the same, and the expression level of hic9 had a significant increase (P<0.05) during 18–25 days in the period of transition from irregular to orderly in calcium carbonate deposits,which indicates that hic9 participates in this process and plays a key role in the formation of the macreous layer.
In Press  doi: 10.11964/jfc.20170410821
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Marine fishery fishing operations are carried out in different spatial and temporal scales, and the distribution of fish may vary with the spatial-temporal scale. Spatial and temporal scales play a vital role in the study of marine fishery habitat, but there were few researches on the comparison of habitat suitability index models in different spatial-temporal scales. In this study, based on the statistical data of Scomber japonicus from July to September in 2003—2011, combined with the data of sea surface temperature (SST) and sea surface height (SSH) obtained by ocean remote sensing, using arithmetic mean model (AM) and the relationship between SST and SSH to build habitat suitability index model (HSI). The study divided the sea surface temperature (SST) and sea surface height (SSH) into different spatial and temporal scales. Spatial scales included 0.25°×0.25°, 0.5°×0.5° and 1°×1°, temporal scales included weekly, ten days and monthly. A total of 9 HSI models were constructed in different spatial-temporal scales. The results indicated that spatial scale of 1°×1° and temporal scale of monthly were the most optimum spatial-temporal scales. When HSI value was greater than 0.6, the percentage of fishing effort was 75.42%, and when HSI value was less than 0.4, the percentage of fishing effort is 12.93%. According to the optimum spatial-temporal scales, using the data from July to September in 2012 to verify the optimum model, when HSI value was greater than 0.6, the percentage of fishing effort was 60.89%, and when HSI value was less than 0.4, the percentage of fishing effort is 13.88%. In summary, the spatial and temporal scales of fishing and marine environment factors should be considered during the construction of fishery habitat suitability index model.
In Press  doi: 10.11964/jfc.20170410805
[Abstract](9) [FullText HTML](1) [PDF 894KB](0)
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It is known to all that age and growth study of crustacean is a problem. However, this problem has been solved to some extent as growth increments were found in hard structures such as eyestalk and gastric mill of crustacean. Fenner penaeus orientalis as one of important economic shrimp, the study of age and growth has been widely concerned. This paper collected 69 F. orientalis from the coastal waters of Nantong, Jiangsu Province. The microstructures of eyestalks of these F. orientalis were analyzed, and the relationship between growth bands of the eyestalks and the weight of F. orientalis was studied. Research shows that the eyestalks consists of four parts: epicuticle, exocuticle, endocuticle and membranous layer. Eyestalk has growth bands and growth increments obviously. Among 44 clear microstructure samples, there are 33 samples with 0 growth band, and 11 samples with 1 growth band. The number of growth increments in one growth band is 25 to 37. The number of growth increments and the length and weight of F. orientalis showed Logistic relation. We conclude that the formation of growth bands of eyestalk in F. orientalis is yearly. However, the formation of growth increments is not daily. Whether the formation period of growth increment is different from the individual differences and the growth environment differences of F. orientalis needs further experimental verification. The results not only lay the foundation for the future identification of F. orientalis, but also provide a new method for the domestic identification of shrimp and crabs and their growth.
In Press  doi: 10.11964/jfc.20180511278
Abstract:
In order to investigate salt tolerance and immune response under high-salt stress in postlarvae of Litopenaeus vannamei, a 30-day feeding trial was conducted with different high-salt stress (40, 50, 60, 65 and 30 as CK). Body weight were detected at the start and end of the trial to get average daily gain, and the activities of T-ATPase, Na+-K+-ATPase, ACP, AKP, SOD, CAT, LZM and MDA were detected at the end of the trial. The results showed that high-salt stress significantly inhibited average daily gain of postlarvae. The average daily gain showed decreasing trend with the increase of salinity, those of salinity 40, 50, 60, 65 were 84.53%, 60.99%, 46.19% and 27.71% compared with 30, respectively; Survival rate decreased significantly as salinity increased. The T-ATPase activity of postlarvae showed a tendency to decrease first and then stabilize at about 1.4 U/mg prot with salinity increasing. However, the change trend of Na+-K+-ATPase activity was opposite to T-ATPase activity. When salinity was 60 and 65, the activity of Na+-K+-ATPase was stable. In addition, high-salt stress also significantly affected the activities of non-specific immunity enzymes of L.vannamei postlarvae. With the increase of salinity, the enzymes activities of T-SOD and CAT had the same trend, rising first and decreasing then. Their highest values, 16.118 U/mg prot and 1.378 U/mg prot respectively, were detected at the salinity of 50. The changes of ACP and AKP activities were positively correlated with salinity. Under different salt stress treatments, the content of MDA changed significantly, and LZM content did not significantly change at all salinity levels. The result indicated that the higher salinity, the slower the growth rate and the increase of the energy for osmotic regulation of L.vannamei postlarvae. In a certain salinity range, high-salt stress can stimulate some non-specific immunity enzymes to cope with the salt stress environment and reduce the damage to the body.
In Press  doi: 10.11964/jfc.20171111021
[Abstract](10) [FullText HTML](6) [PDF 714KB](0)
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In order to establish a quick and accurate determination method of whether the oocyte of Chinese mitten crab (Eriocheir sinensis) is mature or not, a series of experiments were carried out referred to the clearing solution’s ingredients of oocyte in zebrafish. Finally, we found that the mixture of 60 percent of ethanol, 1 percent of acetic acid and 30 percent of formaldehyde was useful for the oocyte of Chinese mitten crab. White spots could be observed in immature oocytes after treated with the mixture, while in mature oocytes, no white spot could be seen. And it is consistent with the result of optical microscopy and HE staining. Obviously, the mixture of 60 percent of ethanol, 1 percent of acetic acid and 30 percent of formaldehyde could be used to determine whether the oocyte of E. sinensis is mature.
In Press  doi: 10.11964/jfc.10.11964/jfc.20171111034
[Abstract](22) [FullText HTML](18) [PDF 812KB](1)
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Japanese-Spanish mackerel (Scomberomorus niphonius) during spawning seasons were collected from Lüsi spawning ground in the southern Yellow Sea, then transverse sections of otoliths were analyzed from its core to the margin by using laser ablation ICPMS. Element:calcium ratios were integrated with microstructural analysis to produce profiles of different life stages for measured elements. The results revealed that the detected Li, Na, Mg, Fe, Co, Sr and Ba were all heterogeneously distributed on the otolith. However, Ba∶Ca ratio fluctuated sharply with a range of 2.13–5.05 μmol/mol. The Ba concentration was normally high in the otolith cores (0–40 μm), declining rapidly in 40–320 μm areas and being low in the remaining areas (320–1 440 μm). Therefore, Ba∶Ca ratio showed significant difference between life stages (P<0.05): it was significantly higher in hatching stage than in wintering and spawning stages. It indicated that variation in Ba∶Ca ratio was most informative and S. niphonius seemed to prefer high Ba concentrations habitats at the stages of embryonic development and hatching before they soon swam away from this habitat at the stage of post-hatching development. Low Ba concentrations habitats seemed to be preferable for the stage of wintering and spawning. These results provided further evidence for the common migration trajectory.
In Press  doi: 10.11964/jfc.20170910960
[Abstract](12) [FullText HTML](8) [PDF 1298KB](0)
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In the experiment, cartilaginous proteins of Raja porosa were prepared using guanidine-HCl extraction and acetone precipitation, and two antioxidant peptides (RCPE-A and RCPE-B) were subsequently isolated from the tryptic hydrolysates of cartilaginous proteins using ultrafiltration, anion-exchange chromatography, gel filtration chromatography and reversed phase high performance liquid chromatography (RP-HPLC). The amino acid sequences and antioxidant activities including free radical scavenging activity and lipid peroxidation inhibition were also measured. The results indicated that the amino acid sequences of RCPE-A and RCPE-B were identified as Gly-Glu-Glu-Gly-Pro-Arg-Gly (GEEGPRG) and Gly-Glu-Glu-Gly-Thr-Met-Gly-Leu (GEEGTMGL) with molecular weights of 700.71 u and 792.87 u, respectively. RCPE-A and RCPE-B exhibited good scavenging activity on DPPH• (EC50 2.94 and 1.16 mg/mL), HO• (EC50 0.34 and 0.54 mg/mL), ABTS+• (EC50 0.34 and 0.10 mg/mL), and \begin{document}${\rm{O}}_2^ - \cdot$\end{document} (EC50 0.11 and EC50 0.03 mg/mL). In addition, RCPE-A and RCPE-B were effectively against lipid peroxidation in a linoleic acid model system. The antioxidant activities of RCPE-A and RCPE-B were due to the smaller size and the presence of antioxidant amino acids including Gly, Glu, Pro, Arg, Met and/or Leu within their peptide sequences. These results suggested that RCPE-A and RCPE-B might serve as potential antioxidants and be used as food additives and functional foods.
In Press  doi: 10.11964/jfc.20180111123
[Abstract](10) [FullText HTML](6) [PDF 896KB](0)
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In order to induce triploid using cytochalasin B (CB) in Crossostrea sikamea, three effecting factors, including CB concentration, initial time of induction, and duration time of induction, were optimized by the cleavage rate, D larvae rate, and triploidy rate. In addition, the variations of survival rate and triploidy rate were also compared for larvae and adults. The results suggested that the optimal method of triploid induction were 0.5 mg/L CB, 40% first polar body releasing for initial time of induction, and 20 min for duration time of induction. The triploidy rate of 87% was obtained by the optimal method. The first effecting factor for cleavage rate, D larvae rate, and triploidy rate was CB concentration, duration time of induction and initial time of induction, and duration time of induction, respectively. Furthermore, there was insignificant negative relationship between triploidy rate and cleavage rate (R2=0.034). Whereas, the positive relationship was significant between triploidy rate and D larvae rate (R2=0.412). As a result, high triploidy rate and high larvae production could be obtained by decreasing both CB concentration and duration time of induction. The survival rates were 71.27% and 96.09% at 3 days, and 34.14% and 58.80% at 15 days for triploid and control groups, respectively. Comparatively, the survival rate were 53.62% and 44.67% for adults at 450 days (September) in triploid and control groups, respectively. The triploidy rate declined from 87% to 77% during the period of 3 to 9 days. Whereas, the triploidy rate was 59.21%±4.99% on average from 90 to 450 days, suggesting that there was no correlativity between triploidy rate and survival rate, with a small variation of triploidy rate for adults. This study provides valuable data for further exploration into triploidy of C. sikamea.
In Press  doi: 10.11964/jfc.20180111129
Abstract:
E75 is an important regulator of the ecdysone signaling pathway in shrimp. In order to gain insight into the structure and function of this gene, we screened and analyzed all E75 gene transcripts based on the transcriptome and genome data of Litopenaeus vannamei, and identified 6 alternatively spliced LvE75 isoforms (named LvE75-1, LvE75-2, LvE75-3, LvE75-4, LvE75-5 and LvE75-6). LvE75-1/2/4/5/6 contained DBD and LBD domains consistent with E75A/C of Drosophila melanogaster, and LvE75-3 only had LBD domains consistent with Drosophila E75D. During molting process, LvE75s were highly expressed in D3–D4 stage. In adult tissues, various isoforms of LvE75 were expressed in all tissues and were highly expressed in the epidermis, gut and gill, with only LvE75-3 being highly expressed in hepatopancreas, blood cells and lymphoid tissues. According to the conserved domain sequence, we designed primers for double-stranded RNA (dsRNA) interference. In LvE75 gene RNAi samples, qRT-PCR results showed that spo, phm and dib were down-regulated, and shd was up-regulated, indicating that LvE75 might regulate Halloween genes to influence ecdysone synthesis. Br-C and Ftz-f1 were down-regulated and HR3 was up-regulated after LvE75 were interfered, indicating LvE75 might influence the downstream early response genes of ecdysone signal pathway. After continued interference in LvE75 for 12 days, the molting rate was significantly lower compared with control group, but the death rate of dsLvE75 group was significantly higher, suggesting LvE75 gene played an important role in shrimp molting and survival.
In Press  doi: 10.11964/jfc.20180211170
[Abstract](13) [FullText HTML](5) [PDF 901KB](1)
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In Press  doi: 10.11964/jfc.20171011000
[Abstract](32) [FullText HTML](11) [PDF 716KB](1)
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To understand the current population genetic structure of half-smooth tongue sole and explore the trend and status of effective population size (Ne) in half-smooth tongue sole, in this paper, 800 4-month-old half-smooth tongue sole were identified by gender-specific genetic markers, and 297 genetic females were selected. Then64 416 SNP markers were obtained by simplified genome sequencing method (2b-RAD). The genome-wide linkage disequilibrium (LD) was used to obtain the linkage disequilibrium distribution on each chromosome. The effective population size was calculated based on the different physical distances between the markers for each historical generation. In order to analyze the genetic structure of the population of half-smooth tongue sole selected by natural and artificial means, the sizes of 7 different chromosomal fragment lengths were detected. And the results showed that the effective population size two generations ago was only about 29. The high-throughput 2b-RAD sequencing method was first applied to the estimation of the effective population size of aquatic animals, which provided a reference for the breeding work of other aquatic species. The effective population sizes decreased when the historical generation was closer. It is important for half-smooth tongue sole breeding and conservation to estimate the effective population size for current generation.
In Press  doi: 10.11964/jfc.20180311199
[Abstract](10) [FullText HTML](2) [PDF 1456KB](0)
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Kisspeptins are a family of neuropeptides encoded by the Kiss genes and play important roles in the reproduction and the regulation energy balance in vertebrate. In order to identify the sequence information of Trachinotus ovatus Kiss1 (ToKiss1) and its expression response to the different feed types, ToKiss1 was cloned from the Trachinotus ovatus based on its genome sequences and transcriptome sequences, then the expression level of ToKiss1 in liver and intestine tissues were analyzed by qRT-PCR. ToKiss1 is approximately 2 768 bp in length with 3 exons and 2 introns. The whole length of ToKiss1 cDNA was 505 bp, including a 312 bp open reading frame (ORF) encoding 104 amino acids, in which there are a signal peptide and one kisspeptin-10 domain (YNLNSFGLRY). Its tertiary structure consisted of two α-helices and was similar to a pail. Phylogeny analysis proved that the kisspeptin-1 in Osteichthyes has distant relationship with the kisspeptin-1 in Mammalia, Amphibian and Reptilia. The qRT-PCR tissue expression analysis indicated that ToKiss1 mRNA was expressed in brain, intestine, stomach, spleen and muscle with the highest expression level in brain. Feed types significantly affected the expression profile of intestinal ToKiss1 mRNA. The transcription level of intestinal ToKiss1 mRNA in T. ovatus fed with pelleted feed was higher than in those fed with iced fish, and the T. ovatus fed with iced squid had lowest ToKiss1 mRNA expression (P<0.05). However, feed types did not significantly affect the expression profile of hepatic ToKiss1 mRNA. All those results indicated that kisspeptin may play a critical role in digestion and absorption functions of the T. ovatus. The research for the first time focuses on expression difference of ToKiss1 mRNA in liver and intestine of Osteichthyes by feeding different feed types, which benefits further studies on the feeding regulation physiological mechanism of Kiss1 gene of teleost fish.
In Press  doi: 10.11964/jfc.20171211075
[Abstract](12) [FullText HTML](11) [PDF 524KB](1)
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The present study investigated the effect of two states (hunger and refeeding) on the growth performance, body composition and related metabolism of Litopenaeus vannamei. There were 5 treatments in the experiment, which were starvation group (S0), control group (C), experimental group named S1, S2 and S3 (sugar sources: glucose, sucrose, cornstarch, respectively), while the juvenile L. vannamei (1.84±0.23) g continue to feed for 12 days after 12 days of starvation. The results showed that starvation affected body composition of juvenile L. vannamei postlarvae and related enzymes [lipase (LPS), phosphofructokinase (PFK), hexokinase (HK), glutamine synthetase (GS)] significantly; shrimp liver and muscle glycogen were repeated movements, after 8 d starvation glycogen dropped to the lowest value, muscle glycogen decreased significantly after a brief rebound. The weight gain in S3 group was the highest after refeeding, the experimental groups were lower than the C group and it was not significant. The liver glycogen content in S1 was significantly lower, while the muscle glycogen in S3 was significantly higher. The activity of LPS and HK increased greatly during the early days of refeeding, and there was no significant difference in the content of GS and PFK between the experimental groups. The study showed that the glycogen and fat were first used for energy supply during the starvation of L. vannamei, and the refeeding was partly compensated for growth, and the effect of corn starch sugar source feed was the best.
In Press  doi: 10.11964/jfc.20171211111
[Abstract](18) [FullText HTML](8) [PDF 868KB](0)
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In order to investigate the effect of triacontanol on growth of Sargassum horneri, different concentration of triacontanol applied continuously for 20 days, or the thalli were immersed in triacontanol solution at concentration of 0.1, 0.5, 1.0 and 2.0 mg/L) for 24 h and then cultured in normal conditions for 20 days, and then the relative growth rate (RGR), physiological and biochemical indexes (photosynthetic pigment, soluble protein, soluble sugar) and fucoxanthin contents were determined, respectively. The results showed that after continuous application of 5 days, the RGR, chlorophyll a (Chl-a), carotenoid (Car), soluble protein, soluble sugar contents were significantly higher than the control; on the 15th day, the growth of the 2.0 mg/L group was inhibited, and all the physiological indexes decreased significantly; on the 20th day, the growth of the 0.1 mg/L group was still promoted, the other three higher concentration groups were inhibited by different degrees, and the higher concentration of triacontanol, the more obvious inhibitory effect. The immersed group after 5 days of culture, the RGR, Chl-a, Car, soluble protein and soluble sugar contents increased significantly; on the 10th day, the RGR of 0.5 and 1.0 mg/L groups were significantly higher than the control; on the 15th day, there was no significant difference with the control, and considering the physiological and biochemical indexes, 1.0 mg/L group was the most obvious effective group, and the promotion effect could maintain about 10 days after treatment. Fucoxanthin contents were significantly higher than control in treatment groups except continuous application with 2.0 mg/L triacontanol for 20 days, among which the fucoxanthin content increased 79.5% on the 10th day after immersed treatment in 1.0 mg/L triacontanol solution for 24 h. Therefore, continuous application of low concentration of triacontanol (0.1 mg/L) or immersed in 1.0 mg/L triacontanol solution for 24 h every 10 days could significantly promote the growth and accumulation of fucoxanthin of S. horneri.
In Press  doi: 10.11964/jfc.20180111167
[Abstract](11) [FullText HTML](4) [PDF 922KB](0)
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In order to elucidate the transformation rule of fatty acids in body of female Coilia nasus during the spawning migration process, the fatty acid content and its components were determined in different tissues at different ovarian developmental stages (from stage Ⅲ to stage Ⅴ) of female C. nasus collected from the lower reaches of the Yangtze River. The changes in the components and contents of various fatty acids in the ovary, muscle and hepatopancreas were analyzed. The results showed that the total fatty acids content in ovary increased by 148.89 mg/g, in muscle decreased by 109.57 mg/g and in hepatopancreas decreased by 160.58 mg/g, respectively, during the period of ovarian development from stages III to V. The fatty acids components of ovary, muscle and hepatopancreas are basically the same at different ovarian developmental stages. They all contain three types and 24 kinds of fatty acids, including 9 saturated fatty acids (SFA), 6 monounsaturated fatty acids (MUFA) and 9 polyunsaturated fatty acids (PUFA). Among all the fatty acids, the content of oleic acid (C18:1n9c) was the highest, accounting for more than 18% of the total amount of fatty acids in each tissue. During the ovarian development from stage Ⅲ to stage Ⅴ, the content of oleic acid decreased by 86.36% in muscle, increased by 2.62 times in ovary; the content of essential fatty acids C18:2n6 and C18:3n3 decreased by 74.00% and 82.26% in muscle respectively, but increased by 225.87% and 183.96% respectively in ovary; the content of DHA decreased by 2.6 times in muscle, while increased by nearly 3 times in ovary. All of these showed that these fatty acids are closely related to reproductive activities. The present study also found that, the values of ARA/EPA in ovary of stage Ⅳ and stage Ⅴ were all less than 0.46, which means that female C. nasus in the Yangtze River had a good egg quality.
In Press  doi: 10.11964/jfc.20171211090
[Abstract](16) [FullText HTML](5) [PDF 869KB](0)
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Lysozyme is an important immune effector present in phylogenetically diverse organisms, and plays important roles in bacteria elimination. In this study, two I-type lysozymes from Venerupis philippinarum (designated as VpILYZ-1 and VpILYZ-2, respectively) were recombinantly expressed in Escherichia coli BL21 (DE3). The recombinant proteins rVpILYZ-1 and rVpILYZ-2 showed broad spectrum of antimicrobial activities. Especially, the rVpILYZ-1 displayed high lytic activities against V. parahaemolyticus, V. splendidus and M. luteus, while rVpILYZ-2 showed strong microbicidal activities against V. parahaemolyticus. The antibacterial activities of rVpILYZs may be performed by both the enzymatic way and non-enzymatic ways. The optimum pH and temperature for the lytic activities of rVpILYZ-1 were 6.5 and 20 °C, and the highest antimicrobial activities of rVpILYZ-2 was detected at pH 4.5 and 10 °C. Moreover, both rVpILYZ-1 and rVpILYZ-2 possessed the opsonic activities, and the phagocytic activities of hemocytes were boosted after being incubated with rVpILYZ-1 or rVpILYZ-2. These results suggested that VpILYZ-1 and VpILYZ-2 played important roles in the immune responses of V. philippinarum.
In Press  doi: 10.11964/jfc.20180111122
[Abstract](14) [FullText HTML](5) [PDF 1209KB](0)
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We analyzed the growth characteristics of the hybrids named Yunlong grouper, derived from Epinephelus moara and E. lanceolatus, and in this paper, we conducted the comparison of the growth characteristics among three groupers, including Yunlong grouper, E.moara and the Zhenzhulongdan grouper, which were cultivated in the factory condition. After establishing the family of two kinds of grouper, we were investigate the fertilization rate, normal development rate and malformation rate of Yunlong grouper, and measured the growth characteristics of Yunlong grouper and E. moara during 45~245 days. At the same time, we counted the growth index and survival rates of the Yunlong grouper and Zhenzhulongdan grouper during 2~13 month after hatching, and counted the survival rate in 13 months. We adopted One-Way ANOVA and Multiple Comparative Analysis to compared the growth characteristics, and fitted the growth model by Excel software. The results show that the average fertility rate, normal development rate, deformity rate of Yunlong grouper was 55.5%±26.7%, 33.9%±23.6%, 8.3%±0.9%, respectively. Until 245 days old, the body weight and body length of Yunlong grouper was (316.7±57.3) g, (22.5±1.7) cm, respectively, About E. moara, measured length (16.8±1.3) cm, weight (123.2±30.2) g. Yunlong grouper grew faster than E. moara, the body weight of Yunlong grouper was as 2.6 times as E. moara’s, and the body length was about 1.3 times. The growth curve of Yunlong grouper during 45~245 days old was W=0.039 2L2.891 2(R2=0.986 9), which reveals that Yunlong grouper was at allometric growth state in this phase, E. moara’s growth curve was W=0.025 5L3.021 6 (R2=0.990 8), which reveals that it was in lsogony growth pattern in this phase; After 12 months contrast cultivation between Yunlong grouper and Zhenzhulongdan grouper, the result reveals that the survival rate of Yunlong grouper was 97.2%, while Zhenzhulongdan grouper’s was 93.2%~94%, and the body weight and total length of Yunlong grouper was (700.0±247.2) g, (35.3±4.1) cm, respectively. However, the Zhenzhulongdan grouper’s was (28.6±3.5) cm, (550.0±224.8) g, Yunlong grouper’s weight is 1.3 times the weight of Zhenzhulongdan grouper with 1.2 times total length. The result of this study reveals that Epinephelus moara (♀) ×E. lanceolatus (♂) is a ideal hybrid combination, and Yunlong grouper has the advantages of fast growth, low deformity rate, and high survival rate, providing the basis for the study of heterosis, and providing scientific basis for the promotion of Yunlong grouper.
In Press  doi: 10.11964/jfc.20180811386
[Abstract](17) [FullText HTML](8) [PDF 1089KB](0)
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Bromodomain-containing protein (BCP) is a highly conservative protein, which belongs to the bromodomain and extraterminal (BET) protein superfamily. BCP can regulate gene replication and transcription by recruiting different chromosome modifying proteins, and the change of its expression is often associated with the occurrence of tumor and inflammation. Based on the transcriptomic analysis, a cDNA sequence of BCP gene (Lv-BRD), 2 229 bp in length, was isolated from the hemocytes of Litopenaeus vannamei in this study. The sequence has been deposited in GenBank with accession number of MH638256. Using online tools, the sequence was characterized. The deduced protein sequence of Lv-BRD has a conservative bromine domain, indicating that it may be involved in the regulation of cell cycle. Tissue/organ expression was analyzed by qPCR and the result showed that Lv-BRD was mainly expressed in hemocytes, hepatopancreas and gills of shrimp. Expression of Lv-BRD in hemocytes increased significantly in the early stage (0.5–12 hours past infection, hpi) challenge by white spot syndrome virus (WSSV), B. thuringiensis and V. parahemolyticus, suggesting that Lv-BRD is involved in the innate immune response to pathogens in shrimp. These results provided a basis for further studies on the function and mechanism of Lv-BRD in antiviral immunity and interferon regulation of L. vannamei.
In Press  doi: 10.11964/jfc.20171111048
[Abstract](17) [FullText HTML](6) [PDF 1216KB](0)
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The North Pacific albacore tuna (Thunnus alalunga) is one of the main target species of tuna longline fisheries, and the conservation and management of this species have been increasingly concerned by tuna regional management organizations, such as WCPFC. T. alalunga is a kind of highly migratory species mainly living in the tropical and subtropical waters. This species which lives in the North Pacific Ocean generally spawns at the western and central part of the tropics and subtropics in spring and early summer. In the juvenile period of T. alalunga, a number of albacores migrate from the North Pacific to the temperate waters of the eastern Pacific. The spawns will migrate to the western tropical and subtropical regions of the Pacific to spawn. This set of patterns of movement will be juvenile fish recorded. The migratory characteristics of this species can provide an important basis for its sustainable utilization and management. Since the difficulty of sample collection, studies for the age identification of the North Pacific T. alalunga were few. Therefore, we studied the age and growth of T. alalunga in the North Pacific by the species’ spines data from the survey of the long-spines tuna fishery in the North Pacific during the years of 2013 and 2014. The fin rays are the newest manifestation of the biological information of T. alalunga in the North Pacific, providing useful information for the sustainable utilization and management of T. alalunga in the North Pacific. Information on the age and growth is very important for conducting stock assessment of this species. Based on 258 fin ray samples collected on the Chinese tuna longliner " Tianxiang 16” operated in the North Pacific between October 19, 2013 and April 5, 2014, the age and growth of the North Pacific T. alalunga were studied. Three different cutting positions were involved in the processing of section selection, and three functions, the linear function, exponential function and exponential function respectively, were also used to fit the relationships between the fork length and fin ray radius. The Von Bertalanffy growth function of the North Pacific albacore was Lt=112.231×[1-e–0.277(t+1.435)].
In Press  doi: 10.11964/jfc.20171011012
[Abstract](22) [FullText HTML](10) [PDF 751KB](1)
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Five complete cDNA sequences related to Wnt/β-catenin signal pathway, designated wnt2, wnt2bb, wnt3a, wnt8a and ctnnb1, were amplified by RT-PCR and RACE approaches from yellow catfish (Pelteobagrus fulvidraco). The validated cDNAs encoding wnt2, wnt2bb, wnt3a, wnt8a and ctnnb1 were 1 743, 2 133, 1 379, 1 508 and 2 636 bp in length, encoding peptides of 351, 372, 291, 387 and 791 amino acid residues, respectively. The amino acid alignment and phylogenetic analysis revealed that these sequences were relatively conserved among vertebrates, and Wnt/β-catenin genes of P. fulvidraco were more closely related to those of Astyanax mexicanus. All Wnt/β-catenin mRNAs were expressed in nine tested tissues (brain, spleen, kidney, gill, heart, muscle, mesenteric fat, liver and ovary), but at variable levels. Effect of waterborne Cu exposure on ovarian mRNA levels of the five genes of P. fulvidraco were determined. On day 28, wnt3a mRNA levels in the ovary significantly decreased with increasing waterborne Cu concentration, but wnt8a showed the opposite trend. On day 56, mRNA levels of these five genes from the ovary of P. fulvidraco showed no significant differences among the three groups. The present study may be helpful to understand the physiological functions of Wnt/β-catenin pathway in fish.
In Press  doi: 10.11964/jfc.20171011006
[Abstract](10) [FullText HTML](3) [PDF 808KB](0)
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Family selection has emerged as the essential manner of selective breeding in aquaculture. The current artificial selection for Japanese scallop (Mizuhopecten yessoensis) is primarily focused on the apparent characters, e.g. growth, shell color and survival rate. However, the selective breeding in terms of nutritional value of adductor muscle has been rarely reported. Based on the adductor muscle dry weight and fatty acid profile of M. yessoensis, the families harboring higher growth rates were screened out initially and the vital nutritional indicators, i.e. the relative abundances of EPA as well as DHA of total fatty acids, and the ratio of ω-3/ω-6 fatty acids, were further assessed. Among a total of 12 selected families, the growth rates and adductor muscle ratio of B04, B05 and B10 were prominently higher than other families (P<0.05). The relative abundances of EPA and DHA of total fatty acids were all above 45% and the ratio of ω-3/ω-6 fatty acids varied among 10.94 and 12.69 in any individual family. The families, B03, B05, B06, B07, B10, B11 and B12, exhibited superior nutritional performance involving fatty acids of adductor muscle. The highest-quality families of M. yessoensis, i.e. B05 and B10, were successfully selected on a basis of the comprehensive comparative analyses. These results revealed that it was feasible to perform artificial selection in terms of the growth performance and the equally critical fatty acid composition of M. yessoensis. This study provides valuable insights for selective breeding of scallops in aquaculture.
In Press  doi: 10.11964/jfc.20161210668
[Abstract](27) [FullText HTML](9) [PDF 717KB](0)
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In Press  doi: 10.11964/jfc.20171211083
[Abstract](19) [FullText HTML](6) [PDF 777KB](1)
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The study was conducted to investigate the effects of different dietary taurine concentrations on growth performance, body composition, tissue mRNA expression of taurine transporter (TauT) and key enzyme activities of taurine synthesis (cysteine sulfinic acid decarboxylase and cysteine dioxygenase, i.e. CSD and CDO) in juvenile grouper (Epinephelus coioides). Four diets at 0 (0DT), 0.5% (0.5DT), 1.0% (1.0DT) and 1.5% (1.5DT) taurine levels were formulated using casein and gelatin as the protein source. A total of 320 juvenile fish with an average weight of (13.85±0.25) g were randomly divided into 4 groups with 4 replicate tanks at a stock density of 20 fish per tank, and each group of fish was fed one of the same experimental diets to apparent satiation each time during a feeding period of 84 days. Results showed that the feed efficiency, feeding rate, weight gain rate and whole-body crude protein content for fish fed the diets with taurine administration were significantly increased, but hepatosomatic index and whole-body crude lipid content were significantly decreased in comparison with 0DT. The dietary taurine addition significantly upregulated tissue mRNA expression levels of TauT and 1.0DT had the highest level of tissue mRNA expression, which declined with concentrations of taurine, but still was significantly higher than 0DT and 0.5DT. There was a positive correlation between concentrations of taurine in serum, liver, intestine and muscle of juvenile E. coioides and dietary taurine content. The CSD activities in liver, muscle and the CDO activities in plasma, liver, intestine and muscle were significantly decreased by dietary taurine administration, however, the plasma CSD activity was not affected by dietary taurine administration. The results suggested that dietary taurine addition could improve the growth performance of juvenile E. coioides, increase whole-body protein deposit, decrease whole-body lipid deposit, enhance the expression level of TauT mRNA and taurine content in tissues, reduce key enzyme actvities of taurine synthesis. The optimal dietary taurine content for juvenile E. coioides was 0.92% based on the regression analysis between weight gain rate and dietary taurine content.
In Press  doi: 10.11964/jfc.20170910965
[Abstract](9) [FullText HTML](3) [PDF 939KB](0)
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Seaweed Gracilariopsis lemaneiformis is mainly used as the bait for abalone and raw material for agar production in China. This macroalga is widely cultivated along the coasts of China from south to north, but its cultivation period is limited by high temperature in summer. In the current study, the effects of heat and phytohormone treatments on Rubisco large subunit (rbcL) and heat shock protein 70 (HSP70) were investigated by using quantitative real-time PCR and Western blot technologies in G. lemaneiformis. The results showed that transcript and protein levels of rbcL in G. lemaneiformis were inhibited by heat stress (33 °C), however, 100 μmol/L salicylic acid (SA100) and 50 μmol/L methyl jasmonate (MJ50) treatments reduced the inhibition of high temperature on the expression of rbcL. In SA100 and MJ50 groups, the transcriptional expression of rbcL increased to 1.31- and 1.32-fold at 3 h, and the protein levels of rbcL were enhanced to 1.36- and 2.10-fold at 24 h compared to the heat-stress group, respectively. Moreover, SA100 and MJ50 effectively alleviated the inhibition effect of heat stress on Rubisco activity, and recovered the Rubisco activation states. However, the addition of 50 μmol/L abscisic acid (ABA50) mainly inhibited rbcL expression and Rubisco activity. Heat stress stimulated the transcript and protein levels of HSP70; hsp70 transcript expression further rose by 0.53–1.00 times at 3 h, and its protein expression enhanced by 0.93–2.45 times at 24 h in the heat-stress group after applying SA100, MJ50 or ABA50. In conclusion, SA, MJ and ABA play a certain role in regulating the inhibition of photosynthesis enzyme and the induction of heat shock proteins caused by heat stress.
In Press  doi: 10.11964/jfc.20180411226
[Abstract](23) [FullText HTML](7) [PDF 980KB](1)
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By comparing the changes of the microflora during salted-dried processing of the red-fleshed fish (Decapterus maruadsi) and the white-fleshed fish (Trichiurus lepturus), the dominant bacterium with antioxidant activity was also studied. In this paper, Mi-Seq sequencing technology was utilized in two kinds of fish in different processing phases. The results showed that the microflora of the two fishes was mainly distributed in Bacteroidetes and Proteobacteria. At the family level of the initial material, there were 7 and 15 colonies in D. maruadsi and T. lepturus, respectively. All the species in round scad were totally in T. lepturus and Enterbacteriaceae was as common dominant bacteria, accounted for 47% and 26% in D. maruadsi and T. lepturus respectively. From the start of salting, the number of bacteria in both fishes was greatly reduced. Vibrionaceae and Bacillaceae were the common dominant bacteria, the former accounted for an average of 40.3% and 42.2% of D. maruadsi and T. lepturus, and the latter accounted for an average of 16.7% and 13.3%. Among the raw materials, four spoilage bacteria of Enterobacteriaceae, Pseudomonas, Vibrionaceae, and Shewanellaceae were showed in both fishes. The dominant spoilage bacteria in both fishes during salt-dried processing was Vibrionaceae. Lactic acid bacteria (LAB), including Streptococcaceae and Lactobacillaceae, only appeared in T. lepturus. Therefore, during salt-dried processing, the degree of reduction of bacteria in hairtail was greater than that of round scad, and they all showed a decrease. The two fishes contained common bacteria and dominant bacteria, but showed significant differences. The spoilage bacteria of both fishes have been greatly reduced, suggesting that salt-dried processing is beneficial to reducing the possibility of fish corruption. T. lepturus could be selected for LAB isolation for subsequent antioxidant studies.
In Press  doi: 10.11964/jfc.20180411239
[Abstract](17) [FullText HTML](17) [PDF 727KB](9)
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In order to investigate the effects of feed bamboo charcoal on muscle nutrition composition and lipid metabolism-related gene expression in juvenile red tilapia, the healthy juvenile red tilapia with an average body weight of (7.07±0.01) g were randomly divided into 5 groups, with 3 replicates in each group and were kept for 60 days. The quantity of bamboo charcoal in the feed was 0%, 0.5%, 1%, 2% and 4%, respectively. The results showed that: the activity of ALT in the 0.5% and 1% groups was significantly lower than that in the control group. The activity of alkaline phosphatase (ALP) and serum total protein (TP) activities were significant increased in the 1% group. The aspartate aminotransferase (AST), triglyceride (TG) and serum total cholesterol (TC) concentrations in the experimental groups were significantly lower than those in the control group. High density lipoprotein (HDL) increased significantly with the increase of bamboo charcoal concentration. 1% bamboo charcoal group muscle moisture content was significantly lower than the control group; crude protein content of 1%, 2% and 4% treatment groups was significantly lower than that of the control group. Crude fat content and muscle ash that of increased compared with the control group, and significantly increased compared with the control group. Feed bamboo charcoal can increase the content of total unsaturated fatty acid (UFA) in fish muscle, but only 4% group's total unsaturated fatty acid content increased significantly, on the contrary, the content of saturated fatty acids (SFA) in 4% group was significantly lower than that of the control group; C18: 2 and C18: 3n3 treatment in 4% bamboo charcoal treatment group increased significantly compared with the control group, and the C22: 6 in 1% bamboo charcoal treatment group was significantly lower than the control group. With the increase of bamboo charcoal feed, LPL gene and MDH gene expression increased compared with the control group, but only 1% group MDH gene compared with the control group were significantly different. Studies have shown that adding appropriate concentrations of bamboo charcoal can improve the crude fat content, total unsaturated fatty acid (UFA) content, LPL gene and MDH gene expression in fish, and help to change the nutrient composition of fish.
In Press  doi: 10.11964/jfc.20180311201
[Abstract](12) [FullText HTML](6) [PDF 734KB](0)
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To investigate the possibility of feeding the red swamp crayfish (Procambarus clarkii) with biofloc technology, a 30-day short-term experiment was conducted to farm juveniles (9.70±0.32) g using biofloc technology and feeding normal diet. This experiment compared the hydrochemical indexes of two experimental groups during experimental period and compared the growth performance, muscle and hepatopancreas nutrient composition, the digestive enzyme activities in stomach, intestine, hepatopancreas tissues, the antioxidant capacity in hepatopancreas and muscle tissues of two groups, juveniles at the end of the experiment. The results showed that the concentration of total nitrogen (TN), nitrite nitrogen (N\begin{document}${\rm{O}}_2^ -$\end{document}-N), nitrate nitrogen (N\begin{document}${\rm{O}}_3^ -$\end{document}-N) of the biofloc group were all kept at a low level during experimental period. The final weight of the juvenile shrimps, the weight gain rate (WG), the specific growth rate (SGR) and survive rate (SR) showed no significant difference in the two experimental groups under this experiment condition. The content of crude protein of the biofloc was 36.8% which could meet the protein requirement of P. clarkii. However, the crude lipid content of biofloc was significantly lower and affected the crude lipid content of muscle from biofloc group juveniles. The α-amylase (α-AL), lipase (LPS) and cellulase (CL) activities in hepatopancreas of the biofloc group juveniles were significantly higher than that of the diet group juveniles, respectively, while α-AL activity in stomach and intestine was higher in the diet group. No significant difference was found in the pepsin activity between the two experimental groups. Comparing the antioxidant capacity of crayfish juveniles from the two experimental groups, the activity of superoxide dismutase (SOD) in hepatopancreas of juveniles from the biofloc group was significantly higher, and the content of malondialdehyde (MDA) was much lower than that from the diet group. No differences were found in the activities of total antioxidant capacity (T-AOC), catalase (CAT), glutathione reductase (GR) and lysozyme (LZM) in hepatopancreas of juveniles from two experimental groups. In conclusion, the biofloc technology had a positive effect on farming of the red swamp crayfish. And this technology could achieve the same or even better affect than the normal diet feeding.
In Press  doi: 10.11964/jfc.20180411247
[Abstract](12) [FullText HTML](7) [PDF 580KB](0)
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A 16-week feeding experiment was conducted to study the effects of different dietary carbohydrate sources (wheat, barley, corn, white sorghum, cassava) on growth, body composition, overwintering and serum indexes of large-size grass carp (Ctenopharyngodon idella) [initial body weight (400.77±7.45) g]. Every diet was randomly fed by triplicate cages, and each cage (2 m×2 m×2 m) was stocked with 30 fish. After the feeding trail, 15 fishes were kept in original cage for overwintering experiment in 16 weeks . Results show as follows: the weight gain rate (WGR) and protein efficiency ratio (PER) of grass carp in corn group was the lowest among experimental groups, and the feed coefficient ratio (FCR) was the highest, but other four groups had no significant difference; the condition factor (CF) in wheat group, was the highest, body weight (VSI) in corn group, and the hepatic body ratio (HSI) and intestine ratio (ISI) in cassava group were the highest, and these were highest among experimental groups; blood glucose (GLU) in wheat group and total cholesterol (T-CHO) in barley and white sorghum groups were the highest among other groups. The triglyceride (TG) content in the cassava group was significantly lower than that in the other groups. The crude fat of muscle in wheat, barley and corn groups was significantly higher than white sorghum and cassava groups. The crude protein content of muscle in cassava group was significantly lower among other four groups. Hepatic glycogen was significantly higher in the white sorghum and cassava groups than other groups. Muscle glycogen was significantly higher in the barley and white sorghum groups than other groups. After wintering, the weight loss of barley grass carp was significantly higher than that of other groups. The decrease rate of HSI was significantly lower than other groups. The hepatic glycogen content was significantly increased, and the decrease of GLU was significantly less than that of other groups. The crude muscle protein decreased most rapidly. There were no significant differences in weight loss after winter in other groups. The CF was the highest drop rate in wheat group, the HSI decline in corn and cassava groups was significantly greater than other groups. corn group had the largest decrease in VSI. In conclusion, under the puffing process conditions, wheat, cassava, and white sorghum are suitable sugar to be sources to be added in feed for large-size grass carp, and cassava has the lowest weight-increasing costs with growth, weight gain cost, and overwintering as evaluation indicators.
In Press  doi: 10.11964/jfc.20180511302
Abstract:
In order to explore the optimum spectral components for growth and development of thallus of Pyropia haitanensis, the effects of different light qualities (white light, WL; blue light, BL; green light, GL; red light, RL) from light-emitting diode (LED) illuminations on the vegetative growth, developmental differentiation, maximal quantum efficiency of PSⅡ photochemistry and photosynthetic pigment contents of female thalli were studied. Results showed that the average length and fresh weight of thalli under WL after 25 days culturing were 2.42-3.86 and 2.64-4.50 times higher than those of thalli cultured in monochromatic light qualities, respectively. The growth rate of thalli was fastest when cultured in polychromatic WL, while it was limited in the monochromatic lights (BL, GL and RL). RL and GL were significantly adverse for the synthesis of phycobiliproteins. Compared to WL, the thalli under RL and GL decreased by 38.6% and 39.1% of total phycobiliproteins, respectively. However, total phycobiliproteins of thalli under BL were increased by 81.2% compared with that under WL, and the highest Fv/Fm values kept on a continuous uptrend through the whole culturing period suggested that thallus had long-term acclimation to BL. It was noteworthy that both GL and BL accelerated cell differentiation and rapidly motivated the parthenogenetic development in the apical parts of thalli, while WL and RL never had such effects. The pathway of parthenogenetic spores developing into normal parthenogenetic conchocelis were promoted by BL, but blocked by GL. All of the parthenogenetic spore germlings in GL overflowed their cell inclusions and finally hollowed and demised. These results indicated that monochromatic lights limited the vegetative growth of thalli, and significantly affected the photosynthetic pigment components and the maximum photochemical efficiency (Fv/Fm) of PSⅡ, yet BL was favourable for parthenogenetic development of unisexual thalli. It also provided a reference for the further studies on the light adaptation mechanism of the thallus in P. haitanensis.
In Press  doi: 10.11964/jfc.20180411248
[Abstract](10) [FullText HTML](3) [PDF 922KB](0)
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In order to clarify the physiological basis of fast growth traits of an excellent black-shell strain of the Pacific oyster (Crassostrea gigas), feeding and metabolism between the black-shell strain and wild population of C. gigas were compared. Results indicated that at the test temperature (16-32 °C), temperature had significant effects on clearance rate (CR), oxygen consumption rate (OCR) and ammonia excretion rate (AER) of C. gigas. With the increasing of temperature, the CR of the black shell strain of C. gigas began to rise, reached the maximum at 28 °C and then declined, while the CR of the wild population of C. gigas reached the maximum at 24 °C. The OCR and AER of black shell strain and wild population increased with temperature, no significant turning point was found. There were significant differences in CR and AER between black shell strain and wild population of C. gigas. The black shell strain had higher CR and lower OCR than wild population, and had significantly lower AER than wild population at 32 °C. At the test salinities of 15 to 35, salinity had significant effects on CR, OCR and AER of C. gigas. CR, OCR and AER of C. gigas increased firstly and then decreased with increasing salinity. There were significant differences in CR between the black shell strain and wild population of C. gigas. The black shell strain had higher CR than wild population, and its AER was lower than that of wild population in range of salinity 15 to 25. The O∶N ratio of C. gigas reached the maximum at 16 °C and salinity 35, increase in temperature or decrease in salinity reduced O∶N ratio. In the temperature experiment, the O∶N ratio of the black shell strain ranged from 10.52-29.31. In the salinity experiment, the O∶N ratio of the black shell strain ranged from 11.51-22.98. The present results demonstrated that the black shell strain of C. gigas could adapt to high temperature and low salinity environment, and selective breeding of black shell strain of C. gigas could produce oysters that have higher intake of energy and lower metabolic costs.
In Press  doi: 10.11964/jfc.20180711357
[Abstract](9) [FullText HTML](3) [PDF 704KB](0)
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The development and exocytosis of the ring-shaped granules (RG) during the process of fertilization membrane (FM) formation in Scylla paramamosain were investigated by transmission electron microscope. The results are as follows: FM, the second envelope between oocyte and chorin, formed during a complex cortical reation initiated after fertilization. The cortical reation includes the successive exocytosis of two morphologically different granules. Firstly the dense granules underwent exocytosis and formed a thin membrane. After that, RG underwent several rounds of massive and rapid exocytosis, and the material from RG fused and formed a thick membrane. Every round of exocytosis of RG participated in three stages as the placid, the thickening and the swelling of FM. The development of RG happened both in the cortex and the nearby endoplasm mainly at the thickening phase of FM. Numerous RG formed and shifted to the edge of plasm membrane to participate in FM formation by explosive exocytosis. Our study showed that the development of RG was closely connected with two kinds of yolk granules and lipid drops, and mitochondria only appeared at cortex. So we inferred that there may be two kinds of RG forming mechanics in cortex and endoplasm in S. paramamosain. Finally, FM was composed of the two layers, and the newly formed plasma membrane became an inlaying membrane (the third envelope). The importance of yolk and lipid drops and RG in participating in FM formation was discussed at the end of this paper.
In Press  doi: 10.11964/jfc.20180511298
Abstract:
Because of improving resource utilization and reducing environmental pollution, IPA (Intensive Pond Aquaculture) technology has been widely promoted as a new breed aquaculture technology. In order to improve the efficiency of pollution collection and discharge in the process of aquaculture, the method of constructing negative slope bottom is used to reconstruct aquaculture tanks. By establishing a two-dimensional simplified model of aquaculture tank and combining the CFD-DEM simulation and KPLS (Kernel Partial Least-Squares Regression) modeling method, a model that can reflect the relationship between the vertical velocity distribution and the bottom slope was established. On this basis, the model of the particle incipient velocity and the single wide suspended load transport rate in the tank was obtained by the theory of sediment motion. After setting up two performance indexes of particle motion and transportation, the DP-MOPSO (Preference-based Multi-objective Particle Swarm Optimization) method was used to get the optimal bottom slope. The optimization results show that with the increase of the bottom roughness, the optimal gradient is slightly reduced and the range is about 0.013-0.015. The simulation results show that the optimal bottom slope can effectively improve the moving probability and the transport capacity of particles, and for the rough surface, the superiority of the slope bottom is more significant. It shows that it is reasonable to optimize the discharge performance of aquaculture tanks by constructing the bottom slope to change the flow structure.
In Press  doi: 10.11964/jfc.20180611331
[Abstract](2) [FullText HTML](2) [PDF 894KB](0)
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Anaerobic ammonium oxidation and denitrification are the main processes of biological nitrogen removal from sediments. Carbon sources are the key factors regulating anaerobic ammonium oxidation and denitrification. In this study, the static carbon release of lignite and its effect on nitrogen removal from pond sediment were studied. The results show that the carbon release rule of lignite at room temperature accords with the second-order kinetic equation and has the feasibility of being a denitrification carbon source.In the denitrification experiment, it was found that lignite promoted the removal of nitrite nitrogen (N\begin{document}${\rm{O}}_2^ -$\end{document}-N) in the overlying water. The removal rate of N\begin{document}${\rm{O}}_2^ -$\end{document}-N increased with the increase of lignite concentration. When the mass concentration of lignite was 40 g/L, the removal rate of N\begin{document}${\rm{O}}_2^ -$\end{document}-N was up to 99.61%. At this time, the concentration of nitrate nitrogen (N\begin{document}${\rm{O}}_3^ -$\end{document}-N) was also the lowest; at the same time, it was found that the optimum concentration of ammonia nitrogen (N\begin{document}${\rm{H}}_4^ +$\end{document}-N) in water was 10 g/L, and the removal rate was 99.39%. Illumina high-throughput sequencing of anaerobic ammonium oxidizing bacteria in the sediment found that the proportion of Fusarium was the largest (39.6%-71.8%), and the dominant genus was Candidatus Brocadia (13.9%-35.8%), Desulfovibrio (17.1%-34.8%), the proportion of Candidatus Scalindua added to the lignite group was higher than that of the unadded group; fluorescence quantitative PCR showed that with the increase of lignite mass concentration, the abundance of denitrifying bacteria in the sediment increased, while the abundance of anaerobic ammonium oxidizing bacteria was lower than that in the zero-brown coal addition group, indicating that the addition of lignite promoted the sediment denitrification. It has a certain inhibitory effect on anaerobic ammonium oxidation. Studies have shown that lignite has the conditions of denitrifying carbon source and can be used for denitrification of pond culture sediments.
In Press  doi: 10.11964/jfc.20180411229
[Abstract](15) [FullText HTML](4) [PDF 1201KB](0)
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In order to understand the biological function of glucocorticoid receptors (GRs) of Megalobrama amblycephala, we explored the expression characteristics of grs in different tissues and the expression changes of grs and some function genes in the recovery process after stress. Results show that the gr1 was highly expressed in gill, spleen and head kidney, while gr2 was highly expressed in pituitary, liver, intestinal, and so on. During the recovery process, on HPI axis, the expression of gr1 had fluctuations, gr2 significantly up-regulated at the 0 h, and the value of gr1/gr2 was gradually increasing in hypothalamus. The expression of gr1 and gr2 all rose first and then decreased, gr1/gr2 value reached the peak at 2 h in pituitary. The expression of gr1 had fluctuations, whereas gr2 had a low expression at 0 h and 2 h compared with the other time points, gr1/gr2 value gradually decreased in head kidney. In liver, gr1 rose in the early time (0 h and 2 h), and gr2 presented a fluctuating situation, and there was a tendency to reduce the the value of gr1/gr2. At the similar time point the expression of pepck peaked. In Gills gr1 rose first, and then decreased, while the expression of gr2 was subdued in the early time (0 h and 2 h), gr1/gr2 value maintained at a large value during 2-8 h, while the occ expression peaked at 2 h. In skin gr1 and gr2 rose significantly in 2 h, gr1/gr2 in 2-8 h also maintained at a large value, and the occ expression rose first and then decreased. Histology research shows that gill filament was hyperplasia, lymphocyte-like cells increased kidney tissues, while other organizations examined had no obvious pathological changes. All the results indicate that GRs have a complex regulatory mechanism in the stress, and the histological analysis shows that the risks of pathological changes come from the stress.
In Press  doi: 10.11964/jfc.20180511273
[Abstract](11) [FullText HTML](6) [PDF 1343KB](0)
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In order to study the roles of R-spondin1(Rspo1) gene in the sex determination and differentiation of the Qihe crucian carp (Carassius auratus), a natural gynogenesis triploid fish, we cloned its cDNA by using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA 5′ and 3′ ends (RACE). We also examined Rspo1 spatio-temporal expression profiles by real-time PCR, at the same time, expression level of Rspo1 in the testis induced by Letrozole or high temperature treatment was also examined. The results showed that the cDNA of Rspo1 was 1243 bp including a 318 bp 5′-untranslated region (UTR), a 127 bp 3′UTR, and a 798 bp open reading frame (ORF) encoding a polypeptide of 265 amino acids. Sequence analysis revealed that Rspo1 from Qihe crucian carp showed the highest similarity with Cyprinidae fish, while had low similarity with other vertebrates including mammalians and reptiles. Tissue distribution by real-time PCR revealed that Rspo1 was abundantly expressed in the muscle, and then in the ovary, gill, intestine, and was barely detectable in other tissues. The expression of Rspo1 was gradually downregulated from fertilization stage, and then upregulated from the tailbud stage, so Rspo1 might be a maternal factor. Ontogenic analysis demonstrated that Rspo1 was expressed abundantly from 20 days after hatching (dah) in the gonad. However, Rspo1 was upregulated in the gonad of sex-reversed males by Letrozole or high temperature treatment, indicating that Rspo1 exhibited a sexual dimophic expression pattern. These results suggested that, as a maternal factor, Rspo1 might be involved in both the ovarian differentiation and spermatogenesis in the testis of C. auratus.
In Press  doi: 10.11964/jfc.20180911452
Abstract:
In order to discuss the microbial community diversity of vinasse liquid during processing of vinasse fish, the large yellow croaker (Larimichthys crocea) was chosen as a material to produce vinasse fish with traditional pickling technology, and the bacterial flora of vinasse liquid was measured by Illumina HiSeq2500 high-throughput sequencing technique. The results showed that the pH value slightly increased before 5 or 10 days and then gradually decreased in different salt dosage (2%, 5% and 10%). The TVB-N value was all lower than 30 mg/100 g after 30 days of processing and the lowest value was found in 5% salt group. The variation of the pH and TVB-N value in the 5% salt group were basically the same under different ratio of fish and vinasse (1∶1, 1∶1.5 and 1∶2), which indicated that the quality of this vinasse fish was stable during processing. High-throughput sequencing results of 5% salt group showed that the Chao index of the vinasse liquid with 1∶2 was the largest (167), which indicated the highest community richness. The Shannon index of the vinasse liquid with 1:1 was the largest (2.75) and the Simpson index was the lowest (0.109), which indicated the lowest bacterial diversity. The main microbial domains of the vinasse liquid were bacterium which about 17 phyla, 1 unclassified phylum and 143 genera. Proteobacteria, Cyanobacteria and Firmicutes were dominant bacterium, of which Proteobacteria was dominant. Vibrio, Chloroplast norank and Enterobacter were dominant bacterium, and Vibrio was dominant in the early fermentation. The results could provide theoretical basis for the study of microbial community diversity of vinasse fish liquid and references for the control of hygienic safety of drunk aquatic products.
In Press  doi: 10.11964/jfc.20180511291
[Abstract](9) [FullText HTML](5) [PDF 722KB](1)
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In Press  doi: 10.11964/jfc.20180511286
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In this study, we developed a method to separate the GC and SGC of Cherax quadricarinatus by using discontinuous Percoll density gradient centrifugation. The dilution buffer and the combination of density gradient were optimized. We found that the density gradient should be diluted in anti-clotting buffer to prevent hemocytes aggregation, and the discontinuous Percoll density gradient consisted of 20%, 65% and 100%, Percoll provided the best result compare with others. After centrifugation at 1 810 r/min for 20 min, the hemocytes were separated into two layers, corresponding to SGC and GC, respectively. Flow cytometry analysis showed that the purities of both fractions were >95% and the cell mortalities were <1.5%. The isolated cells were in good status and could be readily used for further analysis. This simple and effective method will facilitate the study on the function different hemocytes and thus provide information for disease control.
In Press  doi: 10.11964/jfc.20180111165
[Abstract](10) [FullText HTML](4) [PDF 1008KB](0)
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In order to determine the pathogen and pathogenic characteristics of Ctenopharyngodon idellus haemorrhagic septicemia in a farm of Nanchang, a pathogenic bacteria A1310 was isolated from the liver lesions of the diseased C. idellus. The phenotypic characteristics of the isolated strain A1310 included the morphological characteristics, physiological and biochemical characteristics, pathogenicity, susceptibility test. In addition, the whole genome sequencing, phylogenetic-based on multilocus sequence typing (MLST) and virulence gene were examined. According to morphological, biochemical characteristics, the pathogen was identified as Aeromonas hydrophilia. Artificial infection experiments showed that it is pathogenic to C. idellus after infected with the 1.0×106 CFU/mL bacteria strains culture. Antibiotic sensitivity using 20 antimicrobial agents showed that the isolate was resistant to 7 antibiotics including penicillin, but was sensitive to 5 antibiotics including Kanamycin. The A1310 strain genome sequence contains a total of 96 genes related to toxicity and defense, and most of them are multidrug resistance efflux pump genes, about 22%. MLST typing showed that this isolate was genetically related to the American channel catfish isolates (S15-242、S15-458、S15-591、S15-700). Moreover, the comparative genomic analysis showed that A1310 has at least 80% of the core proteins necessary for a complete T6SS, lacking a segment of vgrG and a segment of vca0109. In conclusion, A. hydrophila A1310 from C. idellus was genetically related to the American channel catfish isolates genetically and contains multiple reported virulence genes of A. hydrophilia. This study expands our knowledge to understand the biological traits of A. hydrophlia. This can provide a certain reference for the effective inspection, prevention, and in-depth study of A. hydrophilia, and it has a certain significance for the prevention and control of C. idellus disease and will be a basis for the disease control during C. idellus culture.
In Press  doi: 10.11964/jfc.20180211191
[Abstract](13) [FullText HTML](3) [PDF 1091KB](0)
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In this paper, a new and highly efficient nitrite-denitrifying bacterium from Poyang Lake was screened and named X10. The physiological and biochemical characteristics, 16S rDNA gene sequence analysis, and the effects of nitrite concentration, pH value, temperature and inoculation amount on the growth and nitrogen removal ability of the strain were researched. Meanwhile, the nitrite degradation capacity of X10 in aquaculture water was also studied. The results showed that the strain X10 was identified as Acinetobacter xylosoxidans. The optimal incubation conditions for the aerobic nitrite-denitrifying strain X10 were: pH, 7.0; inoculation size, 3%; temperature, 30 °C; nitrite concentration, 300 mg/L. Under this circumstance, the degradation rate of nitrite reached to peak at 48 h, up to 99.8%. When X10 bacteria (2×108 CFU/mL) were added into cultured pond water (28°C), the degradation rate of nitrite was 82.6% after 96 h. The safety evaluation test showed that the highly concentration of X10 (5 × 107 CFU/mL) had no lethal effect on Danio rerio and no hemolytic phenomenon was presented. These results indicated that X10 can be applied widely in aquaculture.
In Press  doi: 10.11964/jfc.20180411243
[Abstract](10) [FullText HTML](6) [PDF 1033KB](0)
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A 12-week feeding trial was conducted to investigate the effects of dietary soyasaponins on the growth performance, activities of digestive enzymes, intestinal morphology and intestinal bacterial community of turbot (Scophthalmus maximus). Two isonitrogenous and isolipidic experimental diets (based on 67% fish meal) containing 0% and 0.3% soyasaponins were formulated. The results showed that the growth performance was not affected by dietary soyasaponins, while the activities of intestinal pepsin and amylase were significantly depressed by dietary 0.3% soyasopnins. No obvious changes of intestinal histology were observed between two groups. However the gene expression of intestinal tight junction protein Occludin was significantly declined when 0.3% soyasaponins was added. The analysis of intestinal microbiota showed that Proteobacteria and Halomonas were the most dominant phylum and genus in S. maximus intestine, respectively. LEfSe and MetaStat analysis showed that the abundance of dominant bacteria (Proteobacteria and Shewanella) was significantly increased by dietary 0.3% soyasaponins. Meanwhile, dietary soyasaponins significantly increased the abundance of intestinal saponin-hydrolyzing bacteria. In addition, the abundance of some intestinal potential pathogenic bacteria such as Methylobacterium, Moraxella and Photobacterium, was increased while that of some other pathogenic bacteria such as Ralstonia was decreased by dietary soyasaponins. In conclusion, dietary 0.3% soyasaponins depressed the activities of digestive enzymes, and the gene expression of intestinal tight junction protein Occludin, and altered the intestinal microbiota of S. maximus. Thus, the effects of soyasaponins on fish intestine health, especially intestinal flora, cannot be ignored and deserved more study.
In Press  doi: 10.11964/jfc.20180411259
Abstract:
Nitrite nitrogen is toxic to the aquatic animals. Monitoring the concentration of nitrite nitrogen is very critical for the culture of aquatic animals. Due to the high cost of the current commercial electrode sensor which is used to measure the concentration of nitrite nitrogen in water, this kind of sensor is very difficult to be popularized in a large scale. Therefore, it is an urgent need to develop another novel method to predict the concentration of nitrite nitrogen in water. In this paper, taking the advantage of the established online water monitoring system in our laboratory, the temperature, pH value, dissolved oxygen and oxidation-reduction potential were recorded from the water in tanks. Meanwhile, the actual concentration of nitrate nitrogen in water was measured using alpha-naphthalene colorimetric method. The data after pretreatment were used as the original data which were used for SAE neural network training. Thereafter, unsupervised greed training method was applied. The learnt characteristics were used for the supervision and training of BP neural network. The model was optimized using the back propagation (BP) algorithm. The prediction model R2 of the nitrite nitrogen after training was 0.95, and root mean square error of the prediction (RMSEP) was 0.099 709, indicating that the model could accurately predict the concentrations of nitrate nitrogen in water. The established model will pave a new way for developing online system for monitoring the water nitrate nitrogen concentration in the future.
In Press  doi: 10.11964/jfc.20180311209
[Abstract](9) [FullText HTML](3) [PDF 902KB](0)
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In order to study the relationship between bacterial community composition and grass carp growth in the periphyton substrate systems, the ratios of substrate surface area to pool water surface area were set as 50%, 100% and 150% (S-50, S-100 and S-150). Firstly, the growth traits of grass carp in three systems and control groups were measured, and then the high-throughput sequencing technology was used to analyze the bacterial community composition in the water and the substrates, finally, the relationship between bacterial community and grass carp growth in the culture system was explored. The results showed that the weight gain rate and specific growth rate of grass carp in S-100 and S-150 groups were significantly higher than those in S-50 and control group (P<0.05). The survival rate of S-100 group was significantly higher than other groups (P<0.05). The feed conversion rates of the S-100 and S-150 groups were significantly lower than the control group (P<0.05). Bacterial community analysis demonstrated that 1) the proportion of Gammaproteobacteria increased in the substrates compared with the water, and the bacteria was significantly higher in the S-100 group than the other groups; 2) the bacteria in the water are mainly consist of Flavobacterium, Rhodobacte, Cetobacterium and Planctomyces, and in the substrates Acinetobacter, Pseudomona and Chryseobacterium accounted for a high proportion, and the latter three bacteria were significantly higher in the S-100 group than those in the other groups; 3) at the identifiable species level, Pseudomonas alcaligene and Bacillus cereu were mainly in the substrates, and Pseudomonas faecalis was the highest in the S-100 and S-150 groups. Comprehensive analysis of grass carp growth, bacterial community composition and substrate cost, showed that the best effect was the 100% substrate group, in which there were the high bacterial diversity and potential probiotics ratio, the minimum feed coefficient and the highest of grass carp survival rate and weight gain rate. These data of this study provided the scientific data for the practical application of substrates in the aquaculture.
In Press  doi: 10.11964/jfc.20171111067
Abstract:
In Press  doi: 10.11964/jfc.20171011004
[Abstract](23) [FullText HTML](14) [PDF 1325KB](2)
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The net performance of tuna purse seine is influenced by mesh size, leadline weight, flow velocity and other factors. Most of the purse seine fishing vessels in China are used vessels the age of the vessels is high and the equipment is old. The settling performance of the nets is hardly improved by increasing the weights of the leadline. In order to understand the effect of mesh size on the sinking performance, enclosed effectiveness and net shape, the authors based on our previous research results, net performance measurement at sea and the opinion of the captain, enlarge the mesh size from 260 mm to 390 mm (equivalent to 50%) of the low one third of the main body of the tuna purse seine currently used by the Shanghai Ocean Fishery Co., Ltd. to create a, two model nets with different mesh size in the main body were made by the Tauti rule and the comparative tests were conducted through three shooting patterns at 8 cm/s and one at still water in a professional purse seine test tank of Nichimo Co., Ltd. of Shimonoseki Research Institute. The results show that: both the sinking depth and sinking speed of the experimental net with bigger mesh size (45 mm) are larger than that of the control net with smaller mesh size (30 mm)(Sinking depth increased by an average of 1.6%, and sinking speed increased by an average of 1.1%), indicating that increasing the mesh size can improve the sinking performance of purse seine. The pursing time of the experimental net was 14.3% less than that of the control net, and experimental net also has a good form. The opening areas surrounded by the floatline at the end of shooting are almost identical for both the experimental net and control net; however, at the end of pursing, the opening areas surrounded by floatline of experimental net was 1.33 times than that of the control net and leadlline was 1.79 times than that of the control net, indicating that the bigger mesh netting can provide bigger areas for fish school swimming.
In Press  doi: 10.11964/jfc.20180511297
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Fishery-independent survey is commonly used for collecting high quality biological and ecological data and provides vital parameters for fish stock assessment and management. For fishery-independent surveys, a small cost in the precision as a result of reduced sample size may lead to a much great reduction of survey mortality for the already depleted fishery populations and the ecosystem of fragile estuarine habitats, so that optimization of sampling design is essential for acquiring cost-effective sampling efforts. Computer simulation is usually applied for evaluating sampling designs in identifying an optimal sampling effort to achieve the goals of a survey program. In this study, the effect of sample size on estimation of abundance index was examined for fishery species including Cynoglossus joyneri, Pholis fangi, Chaeturichthys stigmatias, Loligo sp., Oratosquilla oratoria, Charybdis japonica and small-sized fish species in Clupeidae and Engraulidae in a cluster sampling survey based on the data collected from bottom trawl surveys conducted in August, October 2013 and February, May 2014 in the Yellow River estuary and its adjacent waters. The relative estimation error (REE), relative bias (RB), coefficient of variation (CV), and accuracy change rate (ACR) were used to measure the performances (accuracy and precision) of different sampling efforts. In general, these indices including REE, CV and ACR showed similar trends, decreasing with sample size initially and then becoming stable after certain sample sizes during all the four seasons. Most of RB did not show consistently increasing or increasing trends with sampling size. The absolute value of RB of C. japonica, O. oratoria and P. fangi etc showed an obvious increase when the sample size reduced from 3 to 1. The optimal sampling efforts were different for the selected species because the target species had different spatial variabilities. The effects of reducing sampling effort on the precision of abundance index estimation were low when the species had low spatial variabilities. Therefore, the optimal sampling effort for multiple species fishery resources surveys should consider the spatial and temporal distribution patterns of the target species.
In Press  doi: 10.11964/jfc.20180211197
Abstract:
To study the fish community structure in islands area, a fishery-independent survey was conducted in August and December of 2016, February and May of 2017. The cluster analysis, nonmetric multidimensional scaling (nMDS) and biological environment correlation analysis (BIOENV) were used to study the composition of fish community in our study area. A total of 96 species were collected, which belonged to 77 genera, 47 families and 12 orders. The Perciformes has maximum ratio, which accounted for more than 50% of their biomass and abundance. Harpadon nehereus was the dominant species throughout the year. In addition, the dominant species in spring were Psenopsis anomala, Collichthys niveatus,and Cynoglossus robustus; the dominant species in summer were Larimichthys polyactis, Trichiurus lepturus,and Chaeturichthys hexanema; the dominant species in autumn and winter were Collichthys lucidus and Coilia Mystus. The fish community in the Ma’an Archipelago and its eastern waters can be divided into group I (the sites sorrounding island and reef), group II (the sites adjacent to reef), and group III (the sites off to island and reef). There were significant differences in species composition between groups, and seasons (R=0.651~0.977), except the spring group I and group III, group II and group III. BIOENV analysis showed that the bottom water temperature had the most significant impact on the fish community compared to bottom salinity and water depth
In Press  doi: 10.11964/jfc.20180311207
[Abstract](11) [FullText HTML](8) [PDF 947KB](0)
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Carassius auratus herpesvirus (CaHV) is a pathogen that can cause crucian carp disease with acute gill hemorrhages and high mortality. Interactions of functional genes with cellular components, such as cellular organs, are needed by viruses to complete infection and replication. In the present study, bioinformatic analysis, PCR amplification, gene cloning, construting recombinant plasmids, and fluorescence observation of the fish cells (Epithelioma Papulosum Cyprinid, EPC) cotransfected with cellular organs tagged plasmids were used to analyze the characteristics, subcellular localization and colocalization with cellular organs of the protein encoded by the gene CaHV ORF31R (CaHV-31R). As the results show, the encoding protein CaHV-31R is composed of 313 amino acids, which consists a transmembrane domain (248~270 aa) and a typical domain of RNase E/G protein family (40~182 aa). The multiple alignment with homology proteins from 5 different fish hepesvirus exhibits higher identity (100% and 80.7%) with the Janpanese strain ST-J1 and Chinese strain SY-C1, which are both the members of type II Cyprinid hepesviruses, centered identity (26.5%) with CyHV-1 which is the representative member of type I Cyprinid hepesviruses, and lowest identity (20.7% and 18.2%) with the Germanic strain CyHV-3(also named koi herpesvirus, KHV) and Chinese strain (CyHV-3-GZ11), which are both the members of type III Cyprinid hepesviruses. The plasmids pEGFP-31R was constructed by PCR amplification, gene cloning, and then used to transfect EPC cells. pEGFP-31R dispersed distribution in cytoplasm and a little part of spotty distribution circling around outside the nucleus. CaHV-31R can colocalize with two celluar organs with monolayer membrane in cytoplasm, which are endoplasmic reticulum and Golgi aparatus. The results indicate that CaHV-31Ris a gene of Carassius auratus herpesvirus, and is able to encode a protein that colocalize with cellular organs.
In Press  doi: 10.11964/jfc.20171111042
[Abstract](12) [FullText HTML](5) [PDF 804KB](0)
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Melting sea ice in the Arctic facilitates access of human activities under the context of climate warming and also put forward the opportunities and challenges for sustainable exploitation and conservation of fish species in this region. Currently, loss of synthesis analysis on ecological characteristics of Arctic fish species leads to lack scientific and reasonable measures during exploitation and management processes. So it is urgent to analyze ecological characteristics of Arctic fish species. Based on scientific information available on Alaska Arctic marine fish ecology, the present study analyzes the ecological characteristics and importance of 104 fish species from the following aspects, i.e., depth distribution, trophic level, diel vertical migration, seasonal migration, and ecological, traditional culture and commercial importance. The results indicates, generally, Most of Arctic fish species studied are pelagic or mesopelagic and living in continent shelf or shelf slope that shallower than 1 000 m. Most of the fish in the Arctic Alaska have diel vertical movements with daytime descending and nighttime rising. The trophic level of those species are ranged from 3.0 to 4.5 and very few fish species occupy higher or lower trophic levels. The importance of most of fish species keeps unknown and only a few fish species occupy a key role in the Arctic Alaska marine ecosystem, traditional culture and commercial fishery based on the data available. About half of fish species demonstrates either diel vertical migration or seasonal movement. Based on clustering analysis, 5 ecological groups is classified for 104 Arctic fish species with considering depth of distribution, diel vertical migration, seasonal movement and trophic level as variables; however, 3 importance groups can be identified with ecological, traditional culture and commercial importance as variables. The results from the present study can provide data support for further studying on ecology of Arctic fish species and exploitation potential evaluation of Arctic fish resources and provide reference information for China’s participation in potential exploitation of Arctic fish resources and international negotiation.
In Press  doi: 10.11964/jfc.20180211180
[Abstract](11) [FullText HTML](4) [PDF 651KB](0)
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The report studied the identification, drug resistance and the molecular resistance mechanism of five Vibrio strains isolated from diseased Cynoglossus semilaevis. The five strains were identified as V. cyclotrophicus by a biochemical test combined with a molecular method (16S rRNA, HSP60 and mreB genes). The broth dilution method was used to determine the antimicrobial susceptibility of the strains to 14 antimicrobials. The PCR amplification and DNA sequencing were used to detect antimicrobial resistance genes, integrons and the gene cassettes. The results indicated that the five strains were resistant to ciprofloxacin, streptomycin, erythromycin, florfenicol, ampicillin, SMZ, TMP/SMZ and rifampicin, and possesses qnr VC, blaCARB-17, strA, strB, sul genes. Class I intergron、qacEΔ1 and sul1 genes were present in JS291 and JS295 strains. The integron-gene cassettes of JS291 and JS295 were encoding dihydrofolatereductase (dfr16), aminoglycoside-(3″)(9)-adenylyltransferase (aadA2), rifampin ADP-ribosylating transferase (arr-3) and dihydrofolate reductase (dfrA27), respectively. These findings suggest that the five strains exhibited multi-drug resistance; the multi-drug resistance phenotype may be closely related to the antimicrobial resistance genes.
In Press  doi: 10.11964/jfc.20171211098
[Abstract](11) [FullText HTML](5) [PDF 741KB](0)
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To figure out the effect of miRNAs in stripped snakehead fish cell line (SSN-1) upon snakehead vesiculovirus (SHVV) infection, SHVV-infected and mock-infected SSN-1 cells were analyzed by miRNA high-throughput sequencing. The expression of twenty-two miRNAs with levels equal to or higher than 1, 000 reads per million (TPM≥1 000) were determined by qRT-PCR with U6, β-actin, and 5S rRNA as internal control. When U6 gene was used as internal control, no significant changes were observed for β-actin upon SHVV infection, while 5S rRNA was upregulated in SSN-1 cells upon SHVV infection. The results showed U6 gene or β-actin could be used as internal control genes for miRNAs in SSN-1 cells. Furthermore, fourteen miRNAs were selected and their effects on SHVV replication were analyzed. The results showed that eleven miRNAs (miR-27a-3p, miR-26a-5p, miR-30e-3p etc.) promoted, whereas miR-150, miR-216b and miR-100-5p suppressed, SHVV replication. Next, we determined that high-expression miR-100-5p was upregulated at early stage of SHVV infection, while downregulated at later stage. Overexpression of miR-100-5p exhibited significant suppression of SHVV replication, while depletion of miR-100-5p promoted SHVV replication. Our findings presented valuable information for the study of molecular drugs against SHVV.
In Press  doi: 10.11964/jfc.20171211117
[Abstract](15) [FullText HTML](7) [PDF 995KB](0)
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Spotted mackerel (Scomber australasicus) is an important economic species in northwest Pacific. The paper evaluates the Pacific stock biomass by aged-structure Virtual Population Analysis (VPA) and Yield per recruit model, and analyses the utilization of stock biomass by using the mackerel catch and CPUE data of the Pacific group which is supplied by Japan's central fisheries research institute from 1995 to 2015. The results show that the biomass of spotted mackerel remains at a high level. The stock biomass is about 650000 tons in 2015, the average fishing mortality shows a trend of falling volatility and fishing mortality of 2015 is 0.15, the current fishing mortality (Fcur) is 0.33, the spawning potential ratio (SPR) remains 36.5%. There is no growth overfishing and recruitment overfishing. It is also discussed that the fluctuations of natural mortality caused by water temperature change and different fishing age affect the resources of spotted mackerel. The study suggests that the fishery is currently utilized in the sustainable way and has great potential for development. It also suggests that the fishery resource could be developed and utilized by using the management reference point F0.1.
In Press  doi: 10.11964/jfc.20170910958
[Abstract](16) [FullText HTML](7) [PDF 1084KB](0)
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The current study aimed to solve the problems of anesthesia in clinical veterinary medicine of turtles. According to the results of pre-experimental, select the animal medicine recommended clinical anesthetic drugs Telazol(tiletamine: zolazepam=1∶1). Compared the anesthetic effects of different doses of Zoletil on Chinemys reevesiis, and the concentrations of zolazepam and tiletamine in plasma were detected by High Performance Liquid Chromatogram (HPLC), and analyzed with software PKsolver2.0 to research the feature of pharmacokinetics. Zoletil at a dose rate of 25 mg/kg was administered intramuscular to C. reevesiis, The induction time, anesthesia time and recovery time were 0.42, 4.33 and 4.14 h respectively. Zoletil onC. reevesiis anesthesia better, in line with the requirements of clinical surgery. The concentration-time curves of zolazepam and tiletamine in plasma all were described by a 2- and 1-compartment model. And the concentration-time equation of zolazepam and tiletaminewere C=13.462e–0.223t+2.127e–0.055t, C=10.619e–0.203t+0.279e–0.047t, respectively. The major pharmacokinetic parameters were as follows: Cmax=11.695 μg/mL、Tmax=1.060 h and AUC=92.470 μg/ mL·h in zolazepam; Cmax=9.654 μg/mL、Tmax=0.482 h and AUC=56.348 μg/ mL·h in tiletamine. It suggested that blood concentration of zolazepam and tiletamineall reached 8.12 μg/mL and 8.96 μg/mL, respectively, The healthy C. reevesiis into anesthesia, to maintain anesthesia, the blood concentrations of zolazepam and tiletamine Should not be less than 7.18 μg/mL and 4.73 μg/mL.
In Press  doi: 10.11964/jfc.20171010988
[Abstract](17) [FullText HTML](6) [PDF 665KB](0)
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The paper studied the occurrence time and physiological characteristics of slow growth seahorse. Comparisons of the growth, the ratio of RNA/DNA, digestive enzymes and related immune enzymes activities in normal growth seahorses[(8.57±0.61) cm, (1.51±0.38) g] and slow growth seahorse [(6.68±0.35) cm, (0.81±0.14) g]Hippocampus erectuswere studied in a cultural experiment for 110 d. The results showed that the average daily gain, specific growth rate, condition factor and viscera index in the normal growth seahorses were significantly higher than those of the slow growth seahorse, respectively. The normal growth seahorses grew faster than that of the slow growth seahorses after the body length was5.026 cm. The amylase, protease and lipase activities in normal growth seahorses were as the same tendency as those of the slow growth seahorses under different reaction temperatures (5 °C, 15 °C, 25 °C, 30 °C, 35 °C, 45 °C and 55 °C) and pH (2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0). However, the digestive enzymes activities of the former were higher than those of the latter, except amylase activity at 35-55 °C and protease activity at 5–25 °C. The activities of ACP、AKP、T-AOC and SOD in normal growth seahorses were 12.83%, 48.21%, 44.71%and 65.75% more than those of the slow growth seahorses, respectively. The MDA of the normal growth seahorse was only 61.09% of that in the slow growth seahorse, and the ratio of RNA/DNA in the normal growth seahorse was higher 23.75% than that of the slow growth seahorse. The growth, digestion and immunity of he normal growth seahorses were obviously better than those of the slow growing hippocampus when their body length were more 5.026 cm.
In Press  doi: 10.11964/jfc.20180111133
[Abstract](26) [FullText HTML](18) [PDF 1354KB](0)
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In order to identify the pathogen which caused a mass of mortality in farmed Cyprinus carpio var. specularis in Deyang district of Sichuan Province, China, the pathogen of this event was determined following bacteriology, parasite morphological observation, histopathology and PCR detection. The results showed that bacteriological examination was negative whereas parasite was positive with Thelohanellus kitauei. Histologically, intestinal damage is the most serious, where a large number of parasitoid cysts were noted. Morphological observation showed that the total length and width of the spores were about 23–30 μm and 10–15 μm, respectively. In addition, the polar capsule was 11–15 μm long and ovalellipsoidal, which accounts for about 1/3–1/2 of spores. The out layer of the spores covered with a thin colorless and transparent film. One pyriform macronucleus in the upper part and two globular micronuclei near the iodinophilous vacuole. Tissues DNA from infected intestine was identified asT. kitauei(TKF-1) by nest polymerase chain reaction amplification of the 18S SSUrRNA gene and the sequenced 18S SSUrRNA gene of TKF-1 has a homology up to 100% withT. kitauei in Gen Bank. According to the results we confirmed that the death of the C. carpio var. specularis in this region was caused by T. kitauei.
In Press  doi: 10.11964/jfc.20180311206
[Abstract](18) [FullText HTML](5) [PDF 1049KB](0)
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The "white spot disease" caused by the parasitic infection of Cryptocaryon irritans has become one of the most serious diseases in the production of Pseudosciaena crocea. This study aims to investigate the pathogenicity of C. irritans to P. crocea, as well asthe effect of Chinese herbal compound "HD-2" on inhibiting the generation reproduction of parasite C. irritans. The number, size, the hatching rate and number of heatched theront of tomonts produced by natural sicked P. crocea were investigated. Then the survival time and infectivity of theront was determined in vitro. The effects of Chinese herbal compound HD-2 on theront, trophont, and tomont, and the therapeutic effects of oral HD-2 on diseased P. crocea were studied. The results were showed as follows: The total number of tomonts produced by P. crocea was positively correlated to the fish body weight. The average diameter of tomonts were 340.8±64.9 μm and the hatching rate was 76.4%, and each tomont could produce (280±42.5) theronts. The theront could survive for more than 24 h in vitro and lost their infect ability in 20 h after hatching. The 90% lethal dose (LD90) of P. crocea infected with C. irritans in 7 days was 9 712 theronts/fish and the median lethal dose for 50% (LD50) was 4 366 theronts/fish. HD-2 could kill theront effectively. After oral administration with different dose of HD-2 (control, 0; G1, 5 g/kg; G2, 10 g/kg; G3, 15 g/kg) for 30 days, the relative infection intensity of the P. crocea groups challenged with LD50 decreased by 32.0%, 44.5% and 51.8%, respectively. Meanwhile, the volume of tomonts reduced by 35.4%, 36.1% and 37.3% and the hatching rate reduced by 16.3%, 23.3% and 27.9%, respectively. The fish survival rate of G1, G2, G3 challenged with LD90 was 40.0%, 55.0% and 58.3%, which was significantly higher than the control group (only 8.3%). Using HD-2 oral treatment for 15 d, the tomonts produced from diseased fish reduced 73.1%, 87.7%, 93.8%, and the fish mortality rate of the three groups were 58.3%, 36.7% and 21.7%, which were significantly lower than the control group (83.3%). The physiological status of P. crocea in the treated group was significantly better than that of the control group. Therefore, HD-2 oral treatment could effectively interrupt the succession infection of C. irritans, suppress the formation and development of tomonts, reduce the tomont hatching rate and the number of hatching theronts, then inhibit the generation reproduction of parasite C. irritans.
In Press  doi: 10.11964/jfc.20170410777
[Abstract](53) [FullText HTML](23) [PDF 3559KB](7)
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With the aim to explore the molecular mechanism of vitellogenin (Vtg) in Scatophagus argus, we cloned the full-length cDNA sequence of three types of vtg by using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) procedures. The length of the vtgAa cDNA is 5360 bp (GenBank No. KY676847), and it encodes a protein consist of 1696 amino acids. The length of the vtgAb cDNA is 5346 bp (KY654346), and it encodes a protein consist of 1699 amino acids. The length of the vtgC cDNA is 4244 bp (KY676848), and it encodes a protein consist of 1275 amino acids. Sequence analysis showed that three vitellogenin homologs of Scatophagus argus have highest homology with Morone americana (83%, 85% and 85%). VtgAa and VtgAb contain all the three major portions, but VtgC lacks phosvitin (PV). Quantitative real-time PCR (qPCR) assay were employed to determine the mRNA expression of vtgAb in the liver after 17 α-ethynylestradiol (EE2) injection in vivo and hepatocytes after exposure EE2 in vitro. Results of qPCR showed that the hepatic expression of vtgAb was higher than vtgAa and vtgC. 48 h after injection, mRNA expression of vtgAb was extremely increased and obviously decreased after 72 h. The expression of vtgAb mRNA was elevated after EE2 exposure to hepatic cells. Based on our results, expressions of vtgAb could be induced by EE2.
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2019, 43(3): 549-562.   doi: 10.11964/jfc.20180511271
[Abstract](10) [FullText HTML](6) [PDF 1577KB](0)
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Glutamine synthetase (GS) is a widely distributed enzyme in animals and plants, which is involved in various cellular activities. In crustaceans, GS plays a major role in the regulation of energy metabolism and osmotic pressure. In the present report, a full cDNA of the GS gene with 1 965 bp in length was obtained from giant freshwater prawn (Macrobrachium rosenbergii ). The open reading frame (ORF) encoded a 361 amino acid (aa) polypeptide with the predicted molecular weight of 40.75 ku. Analysis of amino acid sequences showed that the GS of M. rosenbergii contained 5 conserved regions that belong to the GS Ⅱ group of invertebrates. Phylogenetic analysis of GS of M. rosenbergii shared the highest identity within the clade of GS from Litopenaeus vannamei, Penaeus monodon, and Fenneropenaeus chinensis with 95% similarities at aa level. Polyclonal antibody against GS of M. rosenbergii was generated. Furthermore, we detected the expression profiles of GS mRNA and proteins in various tissues of M. rosenbergii by quantitative reverse transcription PCR (qRT-PCR) and Western blotting. GS mRNA was differentially expressed in 8 detected tissues of M. rosenbergii before molting in the order of hepatopancreas>muscle>stomach>intestine>gill>heart>brain>haemolymph. The expressions of GS in different tissues were compared before and after molting. The results showed that, except in hepatopancreas, the mRNA expression of GS was up-regulated in the other 7 tissues in the order of brain>gill>stomach>intestine>muscle>heart>haemolymph. By Western blot, the expressions of GS protein in the gill and muscles were up-regulated after molting, which was identical with the expression profiles at mRNA level. In addition, the activity of GS enzyme and the concentration of glutamine were decreased in hepatopancreas after molting, and by contrast, they were increased in the gill, muscle and haemolymph. These results were also identical with the GS mRNA expression. The differentiated expressions of GS gene in different tissues before and after molting suggest that it might be involved in the regulation of energy metabolism and osmotic pressure during the molting.
2019, 43(3): 563-572.   doi: 10.11964/jfc.20180711373
[Abstract](21) [FullText HTML](16) [PDF 1039KB](0)
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In order to make more accurate classification of crustacean blood cells and understand their phagocytic function more clearly, an imaging flow cytometry-based automatic method for Eriocheir sinensis blood cell classification was established, and this new method was further compared with microscopic observation for evaluating their abilities in classifying blood cells through characteristic differences of cytoplasmic granular structure in cells. On this basis, 7.5×108 of Thermo Fisher carboxylate-modified yellow-green fluorescent microspheres with 1 μm diameter were injected through the heart of E. sinensis of (10±3) g weight; proportions of cells containing engulfed microspheres in hemolymph were measured by imaging flow cytometry at 2, 4, 6 and 24 h after injection to analyze the phagocytic efficiency and foreign-body-removing ability of blood cells. The results showed that both microscopic observation and imaging flow cytometry-based classification methods could distinguish 4 blood cell populations from hemolymph of E. sinensis, but the population proportions from both methods were different. The possible reasons might be that populations in microscopic observing classification were divided based on the observable granular structures in each cell, but populations got from imaging flow cytometry method were distinguished by all measurable granular structures in each cell. However, due to lack of quantified specific classification standard, the identification results from microscopic observing were fluctuant and what’s more, this work was also time-consuming and laborious compared with automatic methods. On the contrary, imaging flow cytometry measured all detectable intracellular particulate matters. With updated detection module, redesigned flowing system, and, what’s more, innovative integration of photographic function for each detecting channel, imaging flow cytometry could offer a high-throughput detection, and the data were more objective and reliable than those of manual distinguishing and counting. According to the flow cytometry analyzing, non-granular hemocyte, small-granular hemocyte, intermediate-granular hemocyte, large-granular hemocyte accounted for 40.62%±2.65 %, 36.68%±6.84 %, 7.80%±1.16 % and 16.51%±5.60 % separately of total blood cells from E. sinensis. Lack of transition dots between populations means there are no cell type transformations among 4 cell populations. Phagocytic function of E. sinensis blood cells was analyzed by both of above methods. According to microscopic observing results, all 4 kinds of blood cells could engulf fluorescent microspheres. The less the number of granules in the blood cells, the stronger the phagocytic capability of the blood cells. So, the non-granular hemocytes were the main phagocytic population. From the results of imaging flow cytometry method, proportion of blood cells containing microsphere went up in 2 hours after injection, and quickly reached a peak of 5.69%±0.44% at 4 hours, then followed by a rapid decline during 4–6 hours after injection, which means that E. sinensis blood cells were effective in removing foreign matter from the hemolymph. As it is known that fluorescent microspheres are difficult to be degraded by enzymes in cells, the declining proportion of cells containing microspheres is likely to be caused by such mechanisms as agglutination and immobilization of cycling cells, which help cells leave the E. sinensis’s circulatory system. Imaging flow cytometry is suitable for the classification researches and functional studies of E. sinensis blood cells, it would be more effective when combined with microscopic observation. The blood cells of E. sinensis have strong phagocytic ability. Probably through cell agglutination, E. sinensis could quickly remove invaded foreign matter, which, usually, is difficult to be degraded. These results provide new and important references for related researches, and will facilitate to understand the functions of blood cells in crustaceans more clearly.
2019, 43(3): 573-583.   doi: 10.11964/jfc.20171111061
[Abstract](16) [FullText HTML](6) [PDF 851KB](0)
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The energy metabolism and antioxidant enzyme activities of Scapharca broughtonii at different temperature levels (20, 23, 26 and 29 °C) were studied in the laboratory. The results showed that the ingestion rate and the faecal egestion rate of S. broughtonii decreased with the increase of temperature. One-way ANOVA showed that temperature significantly affected the ingestion rate of S. broughtonii, but had no significant effect on the faecal egestion rate. The oxygen consumption rate and the ammonia excretion rate of S. broughtonii first increased and then decreased with the increase of temperature. Through the energy balance equation, we found that the temperature affected the energy allocation of S. broughtonii. Under the condition of 20 °C, the energy of respiration was accounting for 13.71%, 1.89% in excretion, 22.94% in defecation, and 61.47% in growth. However, when the temperature was above 20 °C, the ingested energy could be significantly decreased. Even negative growth occurred. The analysis of variance showed that the temperature had significant differences on the feeding capacity and growth capacity of S. broughtonii. The activities of antioxidant enzymes in the mantle membrane, gill and hepatopancreas of S. broughtonii were sampled and tested at 0, 4, 8, 12, 24, 48 and 72 h after the treatments of temperature. In the range of 20–29 °C, the activity of T-AOC first increased and then decreased, and it was significantly lower at 29 °C than those at any other temperature groups. The results suggested that the short-term high-temperature stimulation promoted the activities of SOD and CAT, but decreased them beyond 24 h. The activities of SOD and CAT in gill and hepatopancreas were significantly affected by temperature, however, they were not significantly affected by temperature in mantle membrane. GST activity increased significantly with the increase of temperature within 4–12 h, but decreased significantly beyond 24 h, especially when the temperature rose to 29 °C. Our studies have speculated that high temperature may lead to the reduction of antioxidant capacity in the organism, which has a serious impact on the energy metabolism and immune capacity of S. broughtonii. This may be an important reason for high death rate of S. broughtonii in summer. All the results suggest that the temperature for the actual production of S. broughtonii should be maintained below 23 °C. It will generate a large amount of energy consumption of S. broughtonii if the temperature exceeds 26 °C.
2019, 43(3): 584-592.   doi: 10.11964/jfc.20171010991
[Abstract](31) [FullText HTML](12) [PDF 729KB](0)
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Tagging and releasing techniques are commonly used to obtain information on behavior and assess the effects of stock enhancement in marine fishes, which is based on the sampling of tagged population. However, the lack of the field protocol on fish tagging techniques undoubtedly leads to the tag loss or even the death of a large quantity of tagged fish. In this study, Acanthopagrus latus, one of the main stocking species in northern South China Sea, was employed to conducted the 40 days experiment using T-bar anchor tags. Three factors in the key tagging procedures were considered: (a) anesthetized or not (anesthetized or unanesthetized); (b) tagging locations (anterior dorsal muscle or posterior dorsal muscle) and (c) implanted angles (45° or 90°). According to a 2×2×2 factorial design, the experiment was divided into 8 tagged groups and 1 control group, with 3 replicates per group and 30 juvenile A. latus [initial average body length (10.05±0.39) cm] per replicate. Rates of growth, survival and tag retention were evaluated quantitatively by multifactor analysis of variance. The results showed that there was no significant difference in the specific growth rate among groups. Anesthetized or not was the factor that produced very significant difference in survival rate. Tagging locations and implanted angles produced significant difference in tag retention rate. Tagging by T with 45° into the anterior dorsal muscle of A. latus was the optimal procedures, which had the highest survival rate of 95.56% with tag retention rate of 98.89%. Finally, the field protocol suggestion was proposed: ① the fish should be reared no less than 3 days before being tagged; ② the tagging equipment should be sterilized using 75% alcohol for 5 minutes; ③ the fish should be anesthetized using 30 mg/L eugenol solution or MS-222 until they could not maintain equilibrium; ④ the fish should be tagged with angles of 45° into the anterior dorsal muscle; ⑤ the fish should be sterilized using 5% povidone iodine or KMnO4 for 30 minutes; ⑥ the tagged fish should be then reared for 7 days before being released. This study will provide basic data for fish tagging studies in the future.
2019, 43(3): 593-604.   doi: 10.11964/jfc.20170510832
[Abstract](19) [FullText HTML](10) [PDF 1937KB](0)
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The change of surface water temperature affects the habitat distribution of pelagic fishes. According to the chub mackerel (Scomber japonicus) fishery-dependent data from July to December during 2003 to 2012 in the Chinese coastal waters, and sea surface water temperature (SST) from remote sensing, the suitable index (SI) from the fishing effort and the catch per unit effort (CPUE) based on SST were established by using the method of normal distribution. The halntat suitability index (HSI) were estimated by taking the average. The latitude distribution and area change of the most suitable habitat (HSI>0.8) was analysed when the monthly SST increased and declined respectively by 0.5 °C, 1 °C and 2 °C. Results showed that the coastal chub mackerel had an obvious southward shifting tendency when the SST increased, and the most suitable habitat area changed from –73.1% to 44.7% during July to December. There was also an obvious northward shifting tendency when the SST dropped and the most suitable habitat area changed from –54.9% to 123.4% during July to December. The area also had different developing trends. The research suggests that the findings of this article can be used to predict the coastal chub mackerel habitat and its fishing ground under El Nino or La Nina, as well as changes in offshore water in the future.
2019, 43(3): 605-617.   doi: 10.11964/jfc.20180511303
[Abstract](22) [FullText HTML](9) [PDF 1551KB](0)
Abstract:
Hangzhou Bay-Zhoushan inshore waters are the home of many commercial fish species, providing a good place for spawning and habitats. The environments in these areas significantly affect the marine species and its structure. According to the bottom trawl survey, covering 80 stations, in these areas during spring, 2016, we studied the fish and macro-crustacean species assemblage and its spatial distribution. The canonical correspondence analysis (CCA) was used to reveal correlation between functional traits of fish and macro-crustacean species (abundance and size) and environmental variables. The results showed that all the marine species can be divided into five ecological groups (dominant group-Amblychaeturichthys hexanema, demersal fishes, pelagics, shrimp, and crab), with the average abundance 546, 213, 83, 316 and 15 individuals hour, respectively. The average size for these ecological groups was 0.29, 2.19, 4.96, 0.36 and 6.66 g/individual, respectively. According to five ecological group abundance, bottoms temperature, bottom salinity and surface turbidity, the waters were clustered into two areas: Hangzhou Bay and Zhoushan inshore waters. Abundance of most of the ecological groups significantly differed in two areas, while the size of most groups was not significantly different. As affected by the mixed waters of fresh water runoff and offshore waters, the large abundance of marine communities gathered in Zhoushan inshore areas, which was characterized by high primary production. The CCA analysis showed that environmental variables in the first two axes explained around 25% of the total variation of abundance, and only 11.7% of the total variation of the average size, indicating that the environmental variables played a more important role in explaining the spatial distribution of abundance than in explaining spatial distribution of average size.
2019, 43(3): 618-627.   doi: 10.11964/jfc.20180511274
[Abstract](19) [FullText HTML](7) [PDF 670KB](1)
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2019, 43(3): 628-638.   doi: 10.11964/jfc.20180111124
[Abstract](18) [FullText HTML](6) [PDF 715KB](1)
Abstract:
An 8-week feeding trial was conducted to determine the dietary valine requirement of juvenile sea cucumber Apostichopus japonicus with initial body weight (9.20±0.12) g. Six experimental diets were formulated with the graded valine levels (0, 0.80%, 1.60%, 2.40%, 3.20% and 4.00% dry diets, respectively). The six trial diets were determined to contain valine of [0.61% (D1), 1.14% (D2), 1.46% (D3), 1.73% (D4), 2.17% (D5) and 2.64% (D6) dry diet], respectively. The results showed that: ① No significant differences in the survival rate (SR) were found among dietary treatments ; the weight growth rate (WGR) and the specific growth rate (SGR) increased with increasing levels of valine up to 1.73% diet, and thereafter, declined. ② There were no significant effects on ratio of intestine weight to body wall weight (IBR) and ratio of intestine length to body length (IBL) of sea cucumber. ③ Crude protein and crude lipid of body wall increased initially, then decreased, and crude protein of diet D4 was significantly higher than that of any other groups. Dietary valine significantly increased His, Val, essential amino acids (EAA) and total amino acids (TAA) contents of body wall, but decreased Leu, Ile and Tyr contents. ④ Total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC) increased with the increasing of dietary valine levels and those of D1 were significantly lower than other groups. Malondialdehyde (MDA) content decreased with increasing levels of valine up to 1.73% diet and then increased, and MDA of D4 was significantly lower than those of other groups. ⑤ Protease and lipase increased initially and then decreased, and protease of D3 was significantly higher than that of other groups, however, there was no significantly effect on amylase of dietary valine. In conclusion, appropriate dietary valine improved significantly growth performance and immune response and modified chemical composition and amino acid contents of sea cucumbers. With WGR as evaluation indicator, regression analysis of broken-line model showed that the optimum dietary valine of sea cucumber with body weight 9.20 g was 1.79% (9.18% diet protein).
2019, 43(3): 639-649.   doi: 10.11964/jfc.20171211099
[Abstract](15) [FullText HTML](12) [PDF 986KB](1)
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In order to study the suitable carbon source required by the biofloc formation in Litopenaeus vannamei culture tank, 3 groups added with 3 carbon sources (glucose group, starch group and sucrose group) were designed. Each treatment group set up 3 replicates. The culture period was 20 d. The experiment analyzed influences of adding different carbon sources on biofloc formation, nutritional ingredients, microflora and water quality indexes. The findings showed that when carbon additive amount was 80% of feeding, the biofloc formation could effectively regulate water quality and reduce ammonia nitrogen and nitrite nitrogen level in water body. The concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen concentrations in three carbon sources addition groups were significantly lower than those of control group. The ammonia nitrogen, nitrite nitrogen and nitrate nitrogen concentrations in the starch group were significantly higher than those of the glucose group and sucrose group. The survival rates of the glucose group, starch group, sucrose group and control group were 72.9%, 54.2%, 69.8% and 44.3% respectively. The biofloc settling volume (BFV) in the starch group was significantly lower than the glucose group, while BFV in the sucrose group was the highest. After 13−15 d, three groups tended to be stable. Crude protein contents in glucose group and sucrose group were significantly higher than that of the starch group. There was no significant difference in the glucose group and sucrose group. The essential amino acids-histidine, arginine, methionine and the nonessential amino acids-aspartate, glusate, alanine in the starch group was lower than the glucose group and sucrose group. The essential amino acid index (EAAI) in the glucose group, starch group and sucrose group was calculated at 0.93, 0.89 and 0.92, respectively. The high-throughput sequencing results showed that there were more than 18 species of bacterial community at the phylum level. Proteobacteria and Bacterioidetes in three types of Biofloc had the highest ratio. In the starch group, Bacteriodetes content was significantly higher than other groups, while Planctomycetes and Actinobacteria contents in the sucrose group were obviously higher than the glucose group and starch group. Therefore, different additions of carbon sources in the L. vannamei culture tank affected the biofloc formation, nutritional ingredients, microbial community structure and diversities and improved water quality in different degrees. With the EAAI as the evaluation index, glucose and sucrose can be used as the suitable carbon source choices for L. vannamei culture pond.
2019, 43(3): 650-660.   doi: 10.11964/jfc.20180411221
[Abstract](21) [FullText HTML](8) [PDF 1190KB](0)
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To explore the influence of the external environment on Pyropia haitanensis blades, the effects of different light intensity, temperature, and ratios of nitrogen to phosphorous on the growth and parthenogenesis of thallus were studied through microscopic observation and statistical analysis. When the light intensity is 10-40 μmol/(m2·s), the algae grow slowly, mature late, and parthenogenesis also occurs later; When the light intensity increased to 60-80 μmol/(m2·s), the algae growth accelerated, maturation became early, and parthenogenesis also advanced. When the temperature is 17-20 °C, the algae grow slowly, mature late, and parthenogenesis is postponed; When the temperature rises above 23 °C, the algae growth begins to be inhibited, but the high temperature promotes the maturation of the algae, and parthenogenesis also occurs in advance. The treatment group with a nitrogen to phosphorous ratio of 16∶1 grew faster than other treatment groups (1∶1, 4∶1, 32∶1 and 64∶1), the slowest rate of thallus growth was observed in the 64∶1 ratio of nitrogen to phosphorus, but it is easy to mature and prone to parthenogenesis. Therefore, at the high light intensity, high temperature and high ratio of nitrogen to phosphorus conditions, both the maturation and parthenogenesis of the algae were improved. Culture conditions have important effects on parthenogenesis of P. haitanensis.
2019, 43(3): 661-670.   doi: 10.11964/jfc.20171111035
[Abstract](26) [FullText HTML](11) [PDF 1032KB](0)
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Streptococcosis is a serious disease that threatens the development of Oreochromis niloticus industry in China. In order to make a vaccine of Streptococcus agalactiae with high immune efficiency and simple operation, we constructed a recombinant shuttle-plasmid pNZ8124-Sip which could express Sip protein of S. agalactiae. The recombinant plasmid was electro-transferred into Lactococcus lactis NZ9000 after being identified by enzyme digestion and sequencing analysis. The SDS-PAGE was used to obtain the optimumly induced concentration of nisin and induction time. The Sip protein was purified by Ni-chelating affinity chromatography and tested by Western blot. O. niloticus was vaccinated orally by gavage with different concentration of the recombinant L. lactis NZ9000-pNZ8124-Sip. The ELISA was used to test the change of serum antibody. The relative percent survival (RPS) was obtained by artificial abdominal injection with S. agalactiae.The SDS-PAGE showed that the molecular weight of expressed protein was 48 ku, which is equal to the expected protein size. The recombinant protein mainly existed as soluble protein and inclusion bodies. The concentration of purified protein could reach 7.65 mg/mL. The optimal condition was induction with 100 ng/mL nisin for 6 h. Western blot results showed that the recombinant Sip protein could be specifically combined with the mouse anti-His tag antibody. Oral immunization showed that the serum antibody and the resistance to S. agalactiae were significantly improved in the middle concentration group (2.24×1010 CFU/mL) and the low concentration group (2.24×109 CFU/mL). The RPS of the middle concentration was 41.0%, which was the highest. This study can lay a foundation for research on oral vaccine of O. niloticus against S. agalactiae and has a broad prospect of application.
2019, 43(3): 671-678.   doi: 10.11964/jfc.20171011013
[Abstract](18) [FullText HTML](7) [PDF 767KB](0)
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Antimicrobial agents play an important role in the prevention and treatment of bacterial infections. However, the extensive use of antimicrobial agents, particularly the misuse of antibiotics in the aquatic animal breeding, has led to various issues, such as antibiotic resistance, pollution of breeding environments, and presence of drug residues in livestock, which need to be addressed urgently. In this paper, the effects of exogenous L-cysteine on the susceptibility of Aeromonas hydrophila to florfenicol were studied. The in vitro bactericidal assay found that 4.00 mmol/L L-cysteine could significantly improve the bactericidal effect of florfenicol by 1.9-11.1 times and that the bactericidal effect increased with increasing L-cysteine concentration and exposure time. Tissue bacterial eradication experiments showed that the combination of L-cysteine and florfenicol could significantly eliminate A. hydrophila in liver, spleen and kidney tissue by 4-16 times compared to florfenicol alone. Oral administration or injection with L-cysteine or/and florfenicol showed that the combination of L-cysteine and florfenicol greatly increased the survival rate of infected fish. Moreover, we also found L-cysteine played a certain role in tissue bacteria eradication and fish immune protection. At last, we found that 1.00-4.00 mmol/L L-cysteine increased the susceptibility of A. hydrophila to florfenicol by 2-4 times. We speculate that L-cysteine may enhance the susceptibility of A. hydrophila to florfenicol and increase the bactericidal effect of florfenicol. In summary, L-cysteine as a synergistic agent of florfenicol, can not only improve the bactericidal effect, but also significantly reduce the use of antimicrobial agents. Therefore, we present a novel approach in fighting against A. hydrophila with practical application value.
2019, 43(3): 679-687.   doi: 10.11964/jfc.20180511283
[Abstract](28) [FullText HTML](10) [PDF 919KB](0)
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To detect the localization of Ostreid herpesvirus-1 (OsHV-1) in tissues of shellfish host, a sensitive method was first established based on indirect in situ polymerase chain reaction (ISPCR) technology. Then the method was employed to investigate OsHV-1 distribution pattern in different types of organs of Scapharca broughtonii. To establish the detection method, suitable PCR primers and amplification cycles for indirect ISPCR were selected, which could generate stable and specific amplification of viral DNA in fixed tissues on sections. The concentrations of proteinase K for digesting different types of tissues were also optimized. Finally, in situ hybridization was conducted with digoxigenin-labeled nucleic acid probes prepared using the same primers, and the distribution of OsHV-1 in the sample tissues was shown by immunoenzyme labeling technology. The results showed the optimum number of amplification cycles was 20, and the optimum concentration of proteinase K was 20 μg/mL. We used the optimized indirect ISPCR method to detect and analyze the distribution pattern of OsHV-1 in five different tissues of ark shells (mantle, gill, hepatopancreas, foot and adductor muscle). The results showed that the virus positive signals were mainly distributed in infiltrated hemocytes and fibrobalsts in connective tissues of the mantle, infiltrated hemocytes in hepatopancreas and gills, necrotic muscle cells in foot and adductor muscle. These results showed that the established indirect ISPCR method for detecting OsHV-1 had the advantages of high sensitivity and specificity in fixing the viral position. The method could be used for studying the distribution of OsHV-1 in different tissues and targeted cell types by investigating positive signals of viral nuclear acid in tissue sections. The method could be used for confirmatory diagnosis of OsHV-1 infection, the tissue tropism, invasion routes and pathogenic mechanism of OsHV-1.
2019, 43(3): 688-696.   doi: 10.11964/jfc.20171211077
[Abstract](22) [FullText HTML](11) [PDF 1594KB](0)
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The aim of this paper was to optimize complex biological preservatives consisting of citric acid, thymol and sodium alginate using three-variable, three-level Box-Behnken design to prolong the shelf life of Takifugu rubripes. A quadratic polynomial regression model was established with total plate counts as the response value. The preservation effects of complex biological preservatives were verified by measuring pH, drip loss, TVB-N, TBA, total plate counts and Pseudomonas sp.. The result showed that the optimal ratio of the complex biological preservatives at ice temperature is as follows: 0.68% citric acid, 1.45% thymol and 1.94% sodium alginate. In that condition, the lowest total plate count was 5.50 lg (CFU/g) on the 30th day. What’s more, citric acid and thymol, citric acid and sodium alginate, as well as thymol and sodium alginate had a significant interactive effect. The optimal complex biological preservatives could significantly inhibit the growth of microorganisms, and reduce the contents of TVB-N and TBA. It was proved that the complex biological preservatives could effectively delay the deterioration of T. rubripes, prolonging the shelf life of 15 d to 30 d.
2019, 43(3): 697-705.   doi: 10.11964/jfc.20171111041
[Abstract](17) [FullText HTML](10) [PDF 948KB](0)
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The ultra-high molecular weight polyethylene (UHMWPE)/graphene (GR) nanocomposite fibers were prepared by melt-spinning. The effects of GR contents on the structure, thermal properties, mechanical properties and creep properties of UHMWPE fibers were studied. The results show that the GR in UHMWPE fiber matrix is uniformly disperse at nanometer-scale thickness. When the graphene content increase to 5‰, the GR shows large agglomerates in UHMWPE fiber matrix. Compared with that of pure UHMWPE fiber, the tensile strength and knot breaking strength of GR-modified nanocomposite fibers are significantly increased. Introducing a certain content of GR can effectively enhance the creep resistance of UHMWPE and reduce its creep rate. When the nano-graphene content is 3‰, the breaking strength increases by 31.9% and the creep rate decreases by 27.3%. When the nano-GR was being introduced to UHMWPE, the interaction between the nanoparticles and the polyethylene segment was enhanced, and the limited amorphous regions near the grain boundary increased, and the α transition peak increased and broadened gradually. The nano-modification technology can significantly improve the mechanical properties and creep resistance of ultra-high molecular weight polyethylene fibers. The results provide a theoretical basis for the high performance of fishing materials.