Distribution Characteristics of Methylmercury in Eriocheir sinensis Produced in Zhejiang Province and the Risk of Eating It

Based the detection of content of methylmercury in the meat and butter of Eriocheir sinensis cultured in Zhejiang Province by liquid chromatography-atomic fluorescence spectroscopy,the distribution characteristics of methylmercury were analyzed,and the exposure risk of methylmercury to consumers was evaluated. The results showed that the content of methylmercury in the crab meat was higher than that of the crab butter. According to China＇s national standard and industry standard,the content of methylmercury in the crab meat was lower than the limit and accorded with relevant regulations. According to the reference intake of methylmercury recommended by the World Health Organization（ WHO） and the United States Environmental Protection Agency（ US EPA）,the weekly intake of E. sinensis meat should not exceed 3.2 kg,and the daily intake should not exceed 200g.

Growth, Mortality and Stock Assessment of Squaliobarbus curriculus (Actinopterygii: Cypriniformes: Xenocyprididae) from Lanxi Section of Qiantang River, China

Population dynamics parameters and stock status of Squaliobarbus curriculus (Richardson, 1846) were analyzed from May to September 2021 in the Lanxi section of Qiantang River. FiSAT II software program was used. The growth coefficient K = 0.21 year–1, asymptomatic length L∞ = 39.48 cm, and age at theoretical zero-length t0 = –0.74 years were estimated. The von Bertalanffy growth function was calculated as Lt = 39.48[1 – e–0.21(t + 0.74)]. The growth curve for weight had an inflection at 5.86 years, corresponding to 29.61 cm in standard length and 372.29 g in weight. The natural mortality rate (M), the fishing mortality rate (F), and the total mortality rate (Z) were calculated as 0.51, 0.61, and 1.12 year–1, respectively. The exploitation ratio (E) was 0.54, which is greater than the value of 0.5 suggested by Gull (1971), indicating a probable state of overdevelopment. The annual average stock number and biomass of S. curriculus in the Lanxi section of Qiantang River were 31.86 × 106 individuals and 3656.82 t, respectively.

Salinity Acclimation Induces Reduced Energy Metabolism,Osmotic Pressure Regulation and Transcriptional Reprogramming in Hypotrichida Ciliate Gastrostyla setifera

Coastal and estuarine protists are frequently exposed to salinity undulation.While the tolerance and stress responses of microalgae to salinity have been extensively studied,there have been scarce studies on the physiological response of heterotrophic protists to salinity stressing.In this study,we investigated the physiological response of the heterotrophic ciliate Gastrostyla setifera to a salinity of 3,via a transcriptomic approach.The first transcriptome of genus Gastrostyla was obtained utilizing a group of manually isolated ciliate individuals(cells)and RNA-seq technique.The completeness of the transcriptome was verified.Differentially expressed gene(DEG)analysis was performed among the transcriptomes of G.setifera acclimated in saline water(salinity 3)and those cultured in fresh water.The results demonstrated a significant alternation in gene transcription,in which the ciliate exhibits a transcripttomic acclimation in responding salinity stressing.The up-regulated DEGs were enriched in the pathways of cytoskeleton proteins,membrane trafficking,protein kinases and protein phosphatases.These may represent enhanced functions of ion transport,stress response and cell protections.Pathways involved in energy metabolism and biosynthesis were markedly down-regulated,reflecting decreased cell activity.Particularly,we detected significantly down-regulated genes involved in several pathways of amino acid catabolism,which may lead to accumulation of amino acids in the ciliate cell.Amino acid could act as compatible solutes in the cytoplasm to maintain the osmotic balance in saline water.Overall,this work is an initial exploration to the molecular basis of the heterotrophic protist responding to salinity stressing.The result sheds light on the mechanisms of enhancement of cell protection,reduction of cell activity,and osmotic pressure regulation in ciliates acclimated to salinity.

High Level Expression of Grass Carp Reovirus VP7 Protein in Prokaryotic Cells

Sequences analysis revealed Grass carp reovirus (GCRV) s10 was 909 nucleotides coding a 34 kDa protein denoted as VP7, which was determined to be a viral outer capsid protein (OCP). To obtain expressed OCP in vitro, a full length VP7 gene was produced by RT-PCR amplification, and the amplified fragment was cloned into T7 promoted prokaryotic expression vector pRSET. The recombinant plasmid,which was named as pR/GCRV-VP7,was then transformed into E.coli BL21 host cells. The data indicated that the expressed recombinant was in frame with the N-terminal fusion peptide. The over-expressed fusion protein was produced by inducing with IPTG, and its molecular weight was about 37kDa, which was consistent with its predicted size. In addition, the fusion protein was produced in the form of the inclusion body with their yield remaining steady at more than 60% of total bacterial protein. Moreover,the expressed protein was able to bind immunologically to anti-his-tag monoclonal antibody (mouse) and anti-GCRV serum (rabbit). This work provides a research basis for further structure and function studies of GCRV during entry into cells.

Expression of Outer Capsid Protein VP5 of Grass Carp Reovirus in E.coli and Analysis of its Immunogenicity

Grass carp reovirus (GCRV) is a tentative member of the Aquareovirus genus in the family Reoviridae. The mature virion comprises 11 dsRNA genomes enclosed by two concentric icosahedral proteins shells that is comprised of five core proteins and two outer capsid proteins. The genome sequence and 3D structure demonstrate there is a higher level of sequence homology in structural proteins between GCRV and mammalian orthoreoviruses (MRV) compared to other members of the family. To understand the pathogenesis of GCRV infection, the outer capsid protein VP5, a homology of the μ1 protein of MRV, was expressed in E.coli. It was found that the recombinant VP5 was highly expressed, and the expressed His-tag fusion protein was involved in the formation of the inclusion body. Additionally, specific anti-VP5 serum was prepared from purified protein and western blot demonstrated that the expressed protein was able to bind immunologically to rabbit anti GCRV particle serum and the immunogenicity was determined by ELISA assay. Additional experiments in investigating the functional properties of VP5 will further elucidate the role of the GCRV outer capsid protein VP5 during entry into host cells, and its interaction among viral proteins and host cells during the infection process.

Replacing fishmeal with soybean meal affects survival, antioxidant capacity, intestinal microbiota, and mRNA expression of TOR and S6K1 in Macrobrachium rosenbergii

Using alternative plant-derived dietary protein to replace fishmeal,combined with practical evaluation indexes,is a recent focus for aquaculture practices.An 8-week feeding experiment with giant freshwater prawn Macrobrachium rosenbergii post-larvae was conducted to determine the eff ects of replacing fi shmeal(FM)with soybean meal in the feed,in terms of growth performance,antioxidant capacity,intestinal microbiota,and mRNA expression of target of rapamycin(TOR)and ribosomal protein S6 kinase B1(S6K1).Four isonitrogenous diets with isocaloric value were prepared to contain 100%,75%,50%,or 25%FM as the protein source(dietary treatments FM100,FM75,FM50,and FM25,respectively).Each diet was fed to post-larval prawns(mean weight 0.045±0.002 g)twice a day in four replicates.No signifi cant diff erence in weight gain was observed among all groups,but the survival rate of prawns fed the FM50 and FM25 diets was signifi cantly lower than that of prawns fed the FM diet.The mRNA expression of both TOR and S6K1 were the lowest in hepatopancreas of prawns fed the FM25 diet.Superoxide dismutase activity of prawns fed the FM25 diet was significantly lower than that of prawns fed FM50.In contrast,the malondialdehyde content was signifi cantly higher in prawns fed FM25 as compared with those fed FM75.The proportion of fishmeal in the diet did not affect the composition of core(phylum-level)intestinal microbiota,but greater fishmeal replacement with soybean meal had a potential risk to increase the relative abundance of opportunistic pathogens in the gut when considered at the genus level.These results suggest that fishmeal replacement with soybean meal should not exceed 50%in a diet for post-larval M.rosenbergii.

Isolation of CYP17 Ⅰ, 3β-HSD and AR Genes from Spotted Sea Bass (Lateolabrax maculatus) Testis and Their Responses to Hormones and Salinity Stimulations

In this study, three cDNA sequences corresponding to cytochrome P450 C17(CYP17 Ⅰ), 3β-hydroxysteroid dehydrogenase(3β-HSD) and androgen receptor(AR) were isolated from spotted sea bass(Lateolabrax maculatus). The mRNA abundances of CYP17 Ⅰ and 3β-HSD increased from stage Ⅱ to stage V with a significant increase at stage Ⅴ, and the highest abundance of AR mRNA was detected at stage Ⅲ in testicular development cycle. CYP17 I, 3β-HSD and AR transcripts were obviously abundant in steroidogenesis tissues such as testis, brain, head kidney among others. Strong and positive signals were observed mainly in interstitial cell regions of L. maculatus testis as were measured with in situ hybridization method. Significant increases of CYP17 Ⅰ and3β-HSD transcripts were detected after 12-48 h hCG(human chorionic gonadotropin) and GnRHa(gonadotropin-releasing hormone analogue) treatments. However, an opposite relationship was found for AR in testis at the same time. In addition, decreasing trends of CYP17 Ⅰ and 3β-HSD mRNA were observed in testis of L. maculatus in freshwater group(FW) from day 2 to day 6, and mRNA abundance of AR increased in brackish water(BW) group from day 4 to day 8. These findings revealed that these three steroid synthesis genes are import for testicular development, hormone and salinity treatment, and provided also an insight into the mechanism of reproductive endocrine of L. maculatus.

Development of Nucleic Acid Sequence-Based Amplification Assay for Detection of Macrobrachium rosenbergii Nodavirus

A nucleic acid sequence-based amplification（NASBA）assay was established for the detection of Macrobrachium rosenbergii Nodavirus（MrNV）.The specific primers were designed according to the high conserved region of RNA2 sequence of MrNV.The 224 bp specific amplification product was obtained in positive sample determined with 3%agarose gel electrophoresis,while no product was generated from shrimp infected with other viruses including DNA viruses（IHHNV,WSSV）and RNA viruses（TSV,IMNV,YHV）.The detecting limit of the assay was 8pg nucleic acid,which is more sensitive than that of PCR method.

Identification and Biological Characteristics of Edwardsiella tarda Isolated from Pelteobagrus fulvidraco

Over the past five years, an epidemic disease broke out in Pelteobagrus fulvidraco ponds of Zhejiang Province. The diseased fish mainly exhibits head splitting and surface bleeding; dissection results reveal hepatonephromegaly and abdominal bleeding. A bacterial strain HSY201301 was isolated from the liver tissue of P. fulvidraco with typical symptoms. Artificial infection experiment confirmed that the isolated strain had a strong virulence to healthy P. fidvidraco, leading to similar symptoms to naturally infected P. fulvidraco. The isolated strain was identified as an Edwardsiella tarda strain according to conventional morphological, physiological, biochemical characteristics and 16S rRNA gene sequence. Results of drug susceptibility test indicated that the isolated strain was sensitive to cipro- floxacin, doxitard, penicillin, doxycycline, and rocephin. This study laid solid foundation for effective prevention and control of E. tarda.

Variation Laws and Influencing Factors of pH in Fishery Waters in Quzhou City

[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlorophyll a(Chl. a) of the fishery waters in Quzhou City from 2017 to 2020, the seasonal variation characteristics and influencing factors of pH in the fishery waters were analyzed and discussed. [Results] The pH of the fishery waters in Quzhou City was in the range of 6.40-11.3, and was characterized by the highest seasonal variation in spring and the lowest in winter. The correlation analysis showed that water temperature and pH were significantly positively correlated in spring and summer(P<0.05), and the photosynthesis of phytoplankton was the main reason that affected the pH of water bodies in spring and summer. There was a negative correlation between water temperature and pH in winter, and the pH in the natural waters had a significant negative correlation with water temperature(P<0.05). The balance of carbonate system in the water bodies was the main reason that affected the pH of water in winter. The level of water eutrophication(Chl. a) affected the pH of fishery waters to a certain extent. When Chl. a<10 μg/L, there was a significant positive correlation between the pH of fishery waters and Chl. a(P<0.05). Various environmental factors had different effects on the pH of different types of fishery waters. The stepwise regression analysis showed that the pH of natural waters was mainly affected by Chl. a, and the pH of aquaculture waters was mainly affected by water temperature and dissolved oxygen. [Conclusions]This study provides certain theoretical support for actual production management.

Purification Effect of Trionyx sinensis Breeding Wastewater by a Synthetic Biological Pond

A synthetic biological pond composed of aquatic plants, a microorganism and aquatic animals was applied in the purification of the wastewater discharged from a Tnonyx sinensis breeding greenhouse, and the removal effects of TN, NH4＋ -N, TP and COD in the wastewater were analyzed. The results show that after the breeding wastewater was purified by the synthetic biological pond for about five months, TN, NH~ -N, TP and COD concentration in the breeding wastewater were reduced by 78%, 92%, 81% and 60% respectively, while DO content in the breeding wastewater increased by about four times, and there was no obvious change in water pH; previous yellow or brown and turbid sewage became yel- lowish and slightly turbid, and it had no smell. It is obviously seen that the purification effect of T. sinensis breeding wastewater by the synthetic biological pond composed of aquatic plants, a microorganism and aquatic animals is obvious, and the synthetic biological pond has good promotion and application prospects.

Quality Analysis and Evaluation of Scylla paramamosain from Three Different Areas

[Objectives]The quality of Scylla paramammosain produced in Fujian,Sanmen and Shanghai were analyzed and evaluated.[Methods]Adult Scylla paramammosain from Fujian,Sanmen and Shanghai were separated for their muscles and gonads,which were analyzed for nutritional components.[Results]The muscle moisture content of S.paramammosain from Sanmen was significantly higher than those in S.paramammosain from Fujian and Shanghai.The muscle protein contents of S.paramammosain from the three regions ranked as Shanghai>Fujian>Sanmen(P<0.05).The muscles of S.paramammosain from Shanghai had the highest crude fat and crude ash contents.The moisture contents of the gonads of the S.paramammosain from the three regions had no significant differences.The protein contents of the gonads of S.paramammosain from the three regions ranked as Shanghai>Sanmen>Fujian(P<0.05).The S.paramammosain from Sanmen had the highest crude fat and crude ash contents in gonads.The contents of 17 amino acids detected in the muscles and gonads of S.paramammosain from the three different regions were different.The total amounts of total amino acids(TAA),essential amino acids(EAA)and flavor amino acids(FAA)in the muscles of S.paramammosain from Sanmen were significantly lower than those produced in Fujian and Shanghai(P<0.05),but the proportions of essential amino acids(EAA)and flavor amino acids were not significantly different.The proportion of EAA and FAA in the gonads of S.paramammosain produced in the three areas were significantly different(P<0.05).There were also differences in the fatty acid composition of the muscles and gonads of S.paramammosain from the three different regions.The proportion of EPA in the muscles of S.paramammosain from Fujian was higher than those of other two groups,but the differences were not significant;the proportion of DHA was significantly higher than those of other two groups,and the differences were significant(P<0.05);and the proportions of n3 PUFA in muscles of S.paramammosain produced in Fujian and Sanmen were significantly higher than that of S.paramammosain produced in Shanghai(P<0.05).The proportions of EPA,DHA and n6 PUFA in the gonads of S.paramammosain produced in Sanmen were significantly higher than those produced in Fujian and Shanghai(P<0.05),while the n3 PUFA was the highest in S.paramammosain produced in Fujian.The proportions of n6/n3 PUFA in S.paramammosain produced in the three different regions were significantly different(P<0.05).In summary,it could be seen that the nutritional composition of S.paramammosain produced in different regions has its own characteristics.[Conclusions]This study provides basic data for the establishment of quality evaluation standards for S.paramammosain,and provides a new perspective for the evaluation of breeding models.

Community Characteristics Analysis of Eukaryotic Microplankton via ITS Gene Metabarcoding Based on Environmental DNA in Lower Reaches of Qiantang River, China

Eukaryotic microplankton plays an important role in water biotic community and in maintaining the stability of water ecosystems. Environmental DNA metabarcoding provides the opportunity to integrate traditional and emerging approaches to discover more new species, and develop molecular biotic indices that can be more rapidly, frequently, and robustly used in water quality assessments. In order to examine assemblages of eukaryotic microplankton in lower reaches of Qiantang River, ITS gene metabarcoding technology based on environmental DNA was carried out. As a result, various species of phytoplankton, fungi and zooplankton were annotated on. More phylum, classes and specieses of eukaryotic phytoplankton and zooplankton were found after compared communities taxa based on metabarcoding with that obtained from morphological examination. Nevertheless, Chlorophyceae was the most common assemblage both identified by using these two methods, also Mesocyclops leuckarti and Acanthocyclops bicuspidatus were both found to be the dominant species of Cyclopoida in the river. Additionally, the reads proportions of phytoplankton and zooplankton at the three freshwater sampling sites (Tonglu, Fuyang and Wenyan) decreased as temperature drop. Meanwhile, twenty classes of fungi were annotated on, of which the community characteristic was first researched in the river. There were significant spatial differences in values of Chao1 index for eukaryotic microplankton. Cluster analysis and Non-metric multidimensional scaling ordination further confirmed that the community composition of eukaryotic microplankton at class level for Jiashao-September sample had the most dissimilarity with the others.

Pharmacokinetic Disposition of Streptomycin Sulfate in Japanese Eel (<i>Anguilla japonica</i>) after Oral and Intramuscular Administrations

Pharmacokinetics and residue elimination of streptomycin sulfate (STR) are important in the determination of optimal dosage regimens and in establishing safe withdrawal periods in farmed fishes. The pharmacokinetics of STR was studied after a single dose (50 mg/kg) of intramuscular (i.m.) or oral gavage (p.o.) administration to Japanese eel (Anguilla japonica) in freshwater at 25°C. Eight fish per sampling point were examined after treatment. Plasma and muscle were collected and analyzed by high-performance liquid chromatography (HPLC) method with 0.05 μg/ml detection limit. The data of pharmacokinetics conformed to the two-compartment open model for intramuscular and one-compartment open model for oral administrations. After intramuscular administration, the elimination half-life (t1/2β) was calculated to be 11.346 h, the maximum plasma concentration (Cmax) to be 29.524 μg/ml, the time to peak plasma streptomycin concentration (Tmax) to be 0.218 h, and the area under the plasma concentration-time curve (AUC) to be 90.206 μg/ml?h. Following p.o. administration, the corresponding estimates were 13.239 h, 0.346 μg/ml, 11.960 h, and 12.356 μg/ml?h. After intramuscular administration, a therapeutic concentration of the drug was maintained for 12 hours in the plasma, however, a therapeutic level could not be achieved after oral administration, and the results suggest that the drug can be used clinically by intramuscular administration against streptomycin susceptible systemic infections in Japanese eel.

Characteristics of a Critical Calcium Transportation Regulator: Plasma Membrane Ca²⁺-ATPase Involved in Calcium Homeostasis from <i>Hyriopsis cumingii</i>(Lea)

Plasma Membrane Calcium ATPase (PMCA) plays a critical role in transporting Ca2+ out of the cytosol across the plasma membrane. Here, a full-length cDNA sequence of plasma membrane Ca2+-ATPase gene was isolated from the gill of Hyriopsis cumingii (HcPMCA) by using SMART RACE technique. The entire cDNA was 5230 bp, including a 417-bp 5'-UTR, a 3588-bp ORF and a 1225-bp 3'-UTR, encoding a 1195-amino acid protein, and no putative signal peptide was predicted. Compared with PMCA homologs from seawater mollusks, HcPMCA had high similarity with them in both sequence and structure. Tissue-specific expression analysis revealed that HcPMCA mRNA was detected in all the sampled tissues, but was prominently expressed in the gill and mantle. When exposed to a serie of increasing Ca2+ that lasted for 7 days, the mRNA expression of HcPMCA in the mantle was slightly downregulated, but peaked at 60 mg/L. Moreover, the temporal expression of HcPMCA transcripts in the mantle after 60 mg/L Ca2+ exposure was shown to be bell-shaped, which was slightly downregulated at 24 h, but upregulated from 24 h to 48 h post-treatment, peaking at 48 h. The result of present study provides useful information for further studies on function and regulation mechanism of HcPMCA gene.

Isolation and Identification of the Pathogens of Bullfrog Streptoccus Disease

The tested strain from typical clinical cases,and the physio-chemical characteristics,16 S rRNA gene sequence and drug sensitivity challenge property were analyzed.This isolate was determined as Streptococcus agalactiae,16 S rRNA gene fragment of 1 280 bp in length.Blast analysis showed that this fragment shared a 100% homology with the conservative region of Streptococcus agalactiae isolate（AB023574）,Streptococcus dysqalactiae isolate（HM146084.1,AB537922,EU075033）,Streptococcus difficilis isolate（AB112407） accessed in Genbank.The isolate was sensitive to ciprofloxacin,neomycin,spectinomycin,furadantin and enoxacin.The results lay foundation for the effective control,rational medication and vaccine preparation for Streptococcus disease on bullfrogs.

Study on Regulating Effects of "Aquatic Environment Protection Oriented Fishery" on Water Environment of Qiaodun Reservoir

In order to evaluate the regulating effect of ＂ aquatic environment protection oriented fishery＂ on aquatic ecosystem,the water quality,plankton community structure,biomass,diversity index,eutrophication index and ecosystem maturity evaluated with Ecopath model were compared from 2010 to 2012 in Qiaodun Reservoir of Zhejiang Province. It was indicated that the water quality had been improved obviously. The water transparency maximally increased by 130%,while TP,TN and CODCrwere reduced. The density and biomass of the plankton were decreased,so was the ratio of Cynobacteria in phytoplankton community. The Shannon-Weaver index was increased; the trophic level was decreased; the ecosystem maturity was improved. By all accounts,the ＂ aquatic environment protection oriented fishery＂ had positive effects on maintaining the balance of reservoir ecosystem and ensuring the safety of drinking water.

CRISPR/Cas9-mediated mutation of Mstn confers growth performance in Culter alburnus juveniles

Myostatin is a member of the TGF-βsuperfamily and functions as a negative regulator for skeletal muscle development and growth.It has become the most targeted gene in aquaculture that used for selective breeding.Previous studies involved in genome editing in several fish species confirmed that CRISPR/Cas9(Clustered Regularly Interspaced Short Palindromic Repeats)system was highly efficient with lower off-target effect,however,no reports were raised in Culter alburnus.In this study,we employed CRISPR/Cas9 gene editing system to successfully disrupt mstn gene by co-injection with Cas9 protein and the targeted sgRNA in C.alburnus.Various Indel mutations were obtained with 82% knockout efficiency in the F0 generation by PCR sequencing.In addition,mutations in mstn that induced by CRISPR/Cas9 were detected in the F1 generation by individually mating the wild-type female with the F0 generation of mstn-KO male at sexual maturity.More importantly,the body weight and length were significantly elevated in mstn±group when compared to those of the control.As expected in mstn±group,the expression level of mstn was sharply reduced,whereas a slight increase was observed in two growth-related genes(myod and myog).Moreover,higher numbers of muscle fibers were observed in mstn±group,meaning that growth performance in mstn±individuals might be represented by increasing the number of muscle fibers.Taken together,our current study successfully obtained a site-specific modification of mstn using CRISPR/Cas9 technology,and these results provided a new insight for facilitating topmouth culter genetic studies and breeding.

Effects of lighting mode on the growth performance,cortisol level and oxidative stress of juvenile Chinese three-keeled pond turtle(Chinemys Reevesii)

To improve the light environment and welfare of the turtle cultured indoors,the effects of lighting mode on growth performance,cortisol level,and oxidative stress of juvenile Chinese three-keeled pond turtle,Chinemys reevesii,were investigated in this study.The experimental turtles with an initial weight of 5.61±0.09 g were reared in tanks under four different lighting modes:three groups with light(lighting the basking area and water area,LBW;lighting the water area only,LW;lighting the basking area only,LB)and control group(no light,NL).The experiment was conducted for more than six months,with each group having three replicates.After 203 d of the experiment,the turtle in the LW group exhibited higher weight gain rate(WGR)and a specific growth rate(SGR,%/d)compared to other treatments.Also,results showed that the final body weight of the turtle exposed to LW was higher than that exposed to other treatments.On the physiological level,serum cortisol level in turtles exposed to LW was significantly lower than that in other treatments.Regarding oxidative stress,the level of catalase(CAT)in turtles exposed to LW and LB was significantly lower than that exposed to LBW and NL.The malonaldehyde(MDA)activity in turtles exposed to LW was significantly lower than other treatments.Based on the growth performance and health status,it is suggested that lighting the water area only is the optimal lighting mode for the juvenile threekeeled pond turtle cultured indoors.

Isolation and characterization of a novel strain(YH01) of Micropterus salmoides rhabdovirus and expression of its glycoprotein by the baculovirus expression system

As one of the most important aquatic fish,Micropterus salmoides suffers lethal and epidemic disease caused by rhabdovirus at the juvenile stage.In this study,a new strain of M.salmoides rhabdovirus(MSRV)was isolated from Yuhang,Zhejiang Province,China,and named MSRV-YH01.The virus infected the grass carp ovary(GCO)cell line and displayed virion particles with atypical bullet shape,300–500 nm in length and 100–200 nm in diameter under transmission electron microscopy.The complete genome sequence of this isolate was determined to include 11 526 nucleotides and to encode five classical structural proteins.The construction of the phylogenetic tree indicated that this new isolate is clustered into the Vesiculovirus genus and most closely related to the Siniperca chuatsi rhabdovirus.To explore the potential for a vaccine against MSRV,a glycoprotein(1–458 amino acid residues)of MSRV-YH01 was successfully amplified and cloned into the plasmid pFastBac1.The high-purity recombinant bacmid-glycoprotein was obtained from DH10Bac through screening and identification.Based on polymerase chain reaction(PCR),western blot,and immunofluorescence assay,recombinant virus,including the MSRV-YH01 glycoprotein gene,was produced by transfection of SF9 cells using the pFastBac1-gE2,and then repeatedly amplified to express the glycoprotein protein.We anticipate that this recombinant bacmid system could be used to challenge the silkworm and develop a corresponding oral vaccine for fish.