Abstract:In order to study the role of the gonad-specific aromatase(P450aromA)encoded by cyp19a1a gene in ovary development of different ploidy cyprinid fishes,molecular cloning and comparative expression patterns of cyp19a1a of gene in different ploidy cyprinid fishes were carried out.By PCR and rapid amplification of cDNA ends(RACE),the full length cDNAs of cyp19a1a in diploid red crucian carp(Carassius auratus red var.),triploid crucian carp and allotetraploid hybrids were obtained.Our data showed that all the cDNAs of cyp19a1a gene in the three different ploidy fishes encode 517 amino acids,which contains transmembrane helix region,I-helix region,Ozol's peptide region,aromatase-specific conserved region and heme-binding region.By RT-PCR using specific primers against the same sequences of coding regions in different ploidy cyprinid fishes,a comparative study of the expression pattern of cyp19a1awas carried out.This result showed that cyp19a1a was preferentially expressed in ovaries of these three fishes,but also was present at much lower levels in testes,brains and spleens.The expression pattern of cyp19a1a in ovaries of different ploidy fishes from the pre-ovulation and the ovulation was also studied by Real-time PCR,and the results showed that the expression of this gene was greatly different among the three different ploidy fishes.In the ovulation and pre-ovulation,the expression of cyp19a1a mRNA in ovary of triploids was the highest among these three fishes.By immunohistochemistry,the CYP19A peptide locations in the ovary of the different ploidy fishes were studied,which indicated that CYP19A was found in follicle cells,outside layer of zona radiate of Ⅳ oocytes,and ooplasm of stage Ⅱ oocytes.These researches showed that there are different expressions of the gonad-specific aromatase during the ovary development in different ploidy cyprinid fishes.In addition,the abnormal expression of cyp19a1a mRNA in triploids might be associated with sterility.

Abstract:Ecological risk of alien species Bullacta exarata in Laizhou Bay was evaluated by analytic hierarchy process(AHP)method using YAAHP software.Evaluation indicators were selected by considering the key characteristics,such as the biology,life history characteristics,human disturbance factors,ecosystem status and so on.In this paper,six primary indexes and 30 secondary indexes were designed.Weights of these indicators were assigned according to the comprehensive analysis of published articles,expert ratings and our in situ measured results.Three risk grades were designed to construct the risk assessment system,which were "allowed introduction","a certain risk" and "forbidden introduction".Software analysis results showed that the values of "a certain risk","allowed introduction" and "forbidden introduction" were 0.507 6,0.352 2 and 0.140 2,respectively.Therefore,the final risk assessment result is "a certain risk".Sensitivity analysis was done by the YAAHP software.In the paper,we only reported the main results of the three highest weights value indicators,incoming,colonization and proliferation risks.Sensitivity analysis results showed that the weight of the three indicators could only influence the sequence of the results of "a certain risk" and "allowed introduction".Therefore,we suggest that we must not blindly introduce and expand the farming scale of the snail and it is better to strengthen supervision and management after the introduction.

Abstract:Glyoxalase Ⅰ(GLOI),an enzyme of the glyoxalase system,is involved in the cellular detoxication,and also plays an important role in the cell cycle and cellular growth.In order to explore the molecular structure and biological function of GLOI in molluscs,GLOI gene of Tegillarca granosa(Tg-GLOI)was cloned by SMART RACE techniques,and characteristics of its amino acid sequence and expression in different tissues and developmental stages were analyzed.The full length cDNA of Tg-GLOI was 1 807 bp,and its complete ORF(Open Reading Frame)was 540 bp encoding 180 amino acids.There was a conserved domain of glyoxalase family at the 27-169 aa in amino sequence of Tg-GLOI.Mature glyoxalase Ⅰ of T.granosa contains two identical subunits,and each subunit was encoded by GLOI gene.The second structure of Tg-GLOI contains eighteen α-helices,twenty parallel β-sheets and thirty-six corners,each of the subunits comprising a Zn²⁺,and the Zn²⁺ binding sites are located within the gap between subunits.Homologous analysis showed that the amino acid sequence of Tg-GLOI shared 86.1% similarity with Crassostrea gigas,and shared more than 70% similarity with those of vertebrates.The results of tissue-specific expression by real time PCR showed that Tg-GLOI gene was expressed in all tissues,and the expression of digestive gland was significantly higher than other tissues(P<0.01).The results of relative expression in different development stages revealed that the expression of Tg-GLOI gene was gradually increased with the process of development,and showed the highest expression in the eyebot larvae stage,which was significantly higher than other stages(P<0.01).And the expression decreased significantly from eyebot larvae stage to juvenile clams(P<0.01)and then stabilized.The results showed that Tg-GLOI had the similar molecular structure as the higher species,and the relative expression revealed significant differences in different tissues and development stages,which laid the theoretical foundation for further study on function and mechanisms of GLOI in molluscs.

Abstract:A 12-week feeding trial was conducted to evaluate the effects of dietary daidzein on growth performance,activities of digestive enzymes,anti-oxidative ability and intestinal morphology in juvenile turbot(Scophthalmus maximus L.)[Mean initial body weight(4.63±0.01)g].Five isonitrogenous and isolipidic diets(crude protein,50%;crude lipid,10.5%)were formulated to contain 0,5,10,20,and 100 mg/kg daidzein,respectively.The feeding trial was conducted in an in-door flowing seawater system.Triplicate groups of 30 fishes were hand-fed to apparent satiation twice daily.After the feeding trial,growth performances,physiological and biochemical parameters were analyzed.The results showed that the growth performances and feed utilization of fish,including final weight(21.24-24.42 g),specific growth rate(1.81-1.98 %/d),feed efficiency(1.01-1.11)and feed intake(1.43-1.51 %/d),were not significantly affected by dietary daidzein supplementation(P>0.05).Similar results were also found in condition factor(1.83%-1.99%),hepatosomatic index(0.72%-0.97%)and viscerosomatic index(4.19%-4.68%)(P>0.05).However,the addition of 5-100 mg/kg daidzein in diet significantly decreased the protein(15.41%-15.59%)and lipid(3.19%-3.93%)contents of fish whole body(P<0.05)without effects on the moisture(77.41%-79.70%)and ash(3.46%-3.81%)contents(P>0.05).The trypsin(35.26-40.66 U/g prot)activity in turbot was significantly(P<0.05)improved by 10-100 mg/kg dietary daidzein whereas the activities of pepsin(31.75-49.56 U/mg prot),intestinal caseinolytic(10.00-14.79 U/mg prot),intestinal amylase(0.05-0.17 U/mg prot)and gastric amylase(0.10-0.25 U/mg prot)showed no significant difference among all treatments(P>0.05).Compared to the control,addition of 5-20 mg/kg daidzein in diet significantly increased the activities of serum superoxide dismutase(SOD)(51.05-53.36 U/mL)and glutathion peroxidase(GSH-Px)(551.40 U/mL),and decreased the content of serum malondialdehyde(MDA)(10.67-11.17 nmol/mL)in fish(P<0.05).No lesion or damage was found on the distal intestine structures of fish from all treatments,however,the height of fish distal intestine fold(391.26-401.48 μm)was significantly increased(P<0.05)by 10-20 mg/kg dietary daidzein.These results suggested that dietary daidzein(5-100 mg/kg)did not affect growth performance of juvenile turbot,while moderate levels of daidzein(10-20 mg/kg)could increase the activities of digestive enzymes,and improve the anti-oxidative ability and intestinal morphology of turbot.The present study provided important information regarding the effects of daidzein on turbot as well as the use of soybean meal in aqua feed.

Abstract:To improve the oyster phenotypic character,9 Crassostrea gigas families,9 C.hongkongensis families and 45 interspecific hybrid families were studied by the method of unbalanced nest design(one male to three female)as subjects in July 2010.Moreover,their medium-term heterosis of hybrids including survival,growth and yield were examined in the identical conditions.These results show as follows:①Survival:The relative high survival rate(87.64%)of hybrid was found with a significant survival advantage(H=189.88),while that of two parental fishes was lower than these of hybrids.Most of C.hongkongensis spat died during overwinter stage,and at the summer temperature was lethal for C.gigas spat.②Growth:The shell height of C.gigas maximum(50.74 mm),which was significantly greater than C.hongkongensis(45.17 mm)and hybrid spats(42.70 mm);and that of hybrids was significantly less than the two parental progenies(H=-10.97).Correspondingly,fresh weight of C.gigas(17.24 g)maximum,which was significantly greater than C.hongkongensis(12.58 g)and hybrid spats(9.47 g).These of hybrids were lighter than two parental species,and the heterosis was 36.46.③Yield:the yield of hybrids(2.98 kg)was middle in that of C.gigas(3.22 kg)and that of C.hongkongensis(0.41 kg)with heterosis(63.97%).In conclusion,we found that hybrids retained the good low temperature resistance,high salt resistance and strong viability,but the growth outbreeding recession occurred in Northern China.Although the hybrid yield was slightly lower than that of C.gigas,hybrid oyster looked very similar to C.hongkongensis.It can be considered as a new line in northern oyster farming.Meanwhile,whether there is heterosis in Southern China needs further study.

Abstract:Eco-substrates technology is known to improve water quality and promote growth of breeding objects in aquaculture.In this study,a 30-day experiment was conducted to investigate the effectiveness of the non-woven eco-substrates for maintaining good water quality and promoting growth in Ctenopharyngodon idella of high density.At the same time,the fish nonspecific immunity,fish intestinal microbial composition,water microbial composition and microbial composition of eco-substrates were analysed in this research.Microbial communities were analyzed by using the PCR-DGGE(PCR-denaturing gradient gel)technology.In treatment group,the non-woven eco-substrates were placed in farming ponds with the density 0.32 m²/m³,which was produced by AquaMats Company.By the end of the test,final fish weight,weight gain and growth rate in treatment group were significantly higher(P<0.05)than control,feed conversion ratio between the two groups was opposite(P<0.05).The serum AKP,ACP,SOD and LSZ activities for treatment group were significantly higher(P<0.05)than control,but iNos and tNOS were significantly lower(P<0.05)in treatment group.At the end of the test,the TSS in treatment group was significantly lower(P<0.05)than control.However,no differences were found between control and treatment group with respect to other water quality parameters.Cetobacterium somerae and Aeromonas veronii were the specific bacteria in control grass carp intestine,which didn't exist in intestine of treatment group.Bacterial community composition similarity between eco-substrates and treatment group water was much higher,and peaked at 63%.Cetobacterium somerae was specific dominant bacteria in control water.Aeromonas veronii existed only in water,and the distribution in control was higher than that in treatment group.Chloroflexi accounted for about 10% of the total bacteria for eco-substrates,but only 5% in water.The results demonstrated that non-woven eco-substrates could be considered a good tool for grass carp,mainly by promoting growth,reducing feed conversion ratio,improving nonspecific immunity and reducing TSS of water.The use of non-woven eco-substrates changed water bacterial community composition,reduced the number of opportunistic pathogens in water and intestine of grass carp.

Abstract:In order to determine the distribution of sIgM in immune organs and the location of SIGM at the subcellular level in Nile tilapia,polyclonal antibody against SIGM fusion protein was prepared in a New Zealand pedigree white rabbit immunized with the purified SIGM fusion protein.For further study on the location of SIGM in the intestine,gill and spleen in Oreochromis niloticus,immunohistochemistry analysis and the immunoelectron microscopy technique were carried out using the prepared polyclonal antibody.The result of the Western blotting revealed that specific antigen-antibody reaction occurred between the antiserum and its corresponding recombinant fusion protein and the antibody titer reached 1:256 000.In the intestine and gill tissues,the positive signals existed in the epithelial cell surface,but not existed in the goblet cells and the mucous cells;while in spleen tissues,the SIGM protein was mainly distributed in some cells in this organ.The immunoelectron microscopy results showed that SIGM mainly existed in the vicinity of intestinal epithelial cell membrane and the surface membranes of the epithelial cells in intestinal microvilli.In the gill epithelial tissue,SIGM mainly existed in the part of the red blood cells and the epithelial cells which surrounded the gill filaments and gill-amella.In the spleen tissue,a large number of colloidal gold particles existed in the secretory vesicles at the internal Golgi apparatus.All these results suggested that sIgM played a critical role in the muscosal immunity of teleost.These provide insights into the roles of fish sIgM in the mucosal immunity.

Abstract:The issue of polar interests and rights is a newly emerging highlight,and polar fisheries activities and involvement in the construction of polar fisheries management regime are a step-forward for "the substantial existence" and realization of polar waters interests and rights.Antarctic and Arctic share such similarities as special geographical locations,fragile ecological environment,and challenges for marine living resources conservation,thus a comparative study is conducted to explore various polar fisheries management issues:fisheries management regulations,fisheries management organizations,fisheries management philosophy,interactions with other international regulations and organizations,responsibilities involving in fisheries management,etc.Based on the comparative study,a further look into the highlights and drawbacks is conducted to explore Antarctic and Arctic fisheries management regimes,which is to facilitate a study about what enlightenment Antarctic and Arctic fisheries management regimes can have on each other.The comparative study provides an opportunity for the exchange of experience in Antarctic and Arctic fisheries management,meanwhile,it enhances the understanding of Antarctic and Arctic fisheries management regimes,which is believed to throw light on the strategies in establishing Chinese polar fisheries policies.

Abstract:An 8-week feeding trial was conducted to investigate the effects of dietary glycyrrhetinic acid(GA)levels on growth,lipid deposition and antioxidant capacity of juvenile blunt snout bream,Megalobrama amblycephala[average initial weight:(15.63±0.04)g].Triplicate groups of fish were fed three times daily with five isonitrogenous and isoenergetic diets containing 0(control group),0.15,0.30,0.45 and 0.60 g/kg GA,respectively.The results indicated that dietary GA levels had little effects on weight gain,specific growth rate,feed conversion ratio,whole body and muscle lipid contents as well as serum triglyceride,free fatty acid and high-density lipoprotein cholesterol levels of blunt snout bream(P>0.05).However,the viscerosomatic index,hepatosomatic index,intraperitoneal fat ratio,liver lipid content and lipoprotein lipase,hepatic lipase and total lipase activities of fish fed GA supplemented diets were all significantly lower than those of the control group(P<0.05).Serum cholesterol concentration of fish fed 0.30-0.60 g/kg GA was significantly lower than that of the control group(P<0.05).Lipase activity increased significantly in the groups fed on diets adding 0.30-0.60 g/kg GA(P<0.05).In addition,liver superoxide dismutase and reduced glutathione activities of fish fed GA supplemented diets were both significantly higher than that of the control group,whereas the opposite was true for malondialdehyde content(P<0.05).In conclusion,dietary inclusion of 0.30-0.45 g/kg GA could reduce the lipid deposition.The mechanism may be that GA could strengthen lipid degradation and enhance lipid metabolism enzymes activities.Moreover,the GA supplemented diets can promote antioxidant capacity in blunt snout bream.

Abstract:Eight half-sib families and 16 full-sib families of F₂ generation of Patinopecten yessoensis were developed as experimental materials for obtaining fast-growth families and evaluating the genetic parameters of growth traits in early and medium-term.Four traits(shell height,shell length,shell width and body weight)were measured from 7-months to 13-months,coefficient of variation and multiple comparison of 4 traits were analyzed,heritability and repeatability were evaluated,and phenotypic correlation and genetic correlation were estimated.The results showed that the variation coefficient of body weight ranged from 37.40% to 69.81%,more than that of other traits,while,the variation coefficient of shell hight ranged from 12.74% to 22.77%,less than that of other traits,which indicated that growth traits of Patinopecten yessoensis had great potential for breeding improvement.Py11-02,Py11-15 and Py11-03 were identified as fast growth families by analysis of multiple comparison of 4 traits.Heritability of shell height,shell length,shell width and body weight were 0.220-0.586,0.151-0.511,0.200-0.742,0.219-0.617 respectively,belong to high or medium heritability.The repeatability of 4 traits were 0.11-0.29,0.08-0.25,0.10-0.36,0.11-0.30 respectively,belong to medium or low repeatability.Phenotypic correlation of shell height,shell length,shell width for body weight were 0.926-0.935,0.929-0.943,0.692-0.981 respectively,all of that reached extremely significant level(P<0.01).Genetic correlation of shell height,shell length,shell width for body weight were 0.908-0.984,0.921-0.975,0.946-0.981 respectively,belong to high genetic correlation.The study can provide some theoretical support for breeding of P.yessoensis.

Abstract:The freshwater pearl mussel(Hyriopsis cumingii),also known as triangle mussel,is a freshwater bivalve widely distributed in China and is the commercially most important mussel species exploited for freshwater pearl production due to its several advantageous pearl production traits.In the paper,study on the investigation,collection and protection of germplasm resources of H.cumingii,development condition of different molecular markers such as RAPD,SSR and mitochondrial gene were introduced and the application of different molecular markers in genetic diversity research in H.cumingii was discussed.Meanwhile the growth performance of H.cumingii from China's five major freshwater lakes and nine reciprocal hybrids F₁ of three excellent germplasm were compared.Then the current research status of pearl formation related genes,immune related genes,shells and pearl color related genes was summarized.And on the basis of interspecific and intraspecific hybridization in H.cumingii,the breeding progress of "kangle" was discussed.Some suggestions for future resarch were put forward,such as using family selection with modern biological technology to breed and promote new varieties which were high yield and quality,meanwhile,study on genome of H.cumingii.This paper provides important scientific basis for genetic improvement of H.cumingii.

Abstract:Partial StAR gene sequence obtained from whole genome sequencing results of half-smooth tongue sole(Cynoglossus semilaevis)and its full-length cDNA sequence were acquired by SMART-RACE.The StAR complete cDNA was 1 294 bp in length containing 852 bp open reading frame(ORF)and encoded 283 amino acids,132 bp 5'un-translated region(5'-UTR)and 310 bp 3'un-translated region(3'-UTR).Alignment analysis of the amino acids sequence with other species showed that StAR of C.semilaevis was 85% similar to most species of StAR including Solea senegalensis,Micropterus salmoides,Lateolabrax japonicus and Sparus aurata.In order to study the relative expression of StAR gene between females and males,and in different stages of male,we chose the real-time fluorescence quantitative methods.The results indicated that StAR mRNA was extremely highly expressed in testis,but was hardly expressed in the ovary of C.semilaevis.From 16 days to 66 days,StAR gene was not expressed in testis.While 150 days the expression was significantly increased,until sexual maturity,StAR mRNA doubled the amount of expression.After the discharge of sperm,the expression declined obviously.This suggests that the gene has great function in the development of testis.To determine the temporal StAR expression,we chose the method of in situ hybridization.The result showed that StAR mRNA was expressed in sperm cells of testis.Our results showed that StAR gene played important roles in the testis maturation and displayed great function during the period of sperm formation.

Abstract:The freshwater pearl mussel,Hyriopsis cumingii,is commercially important for freshwater pearl production in China and contributes more than 95% of the annual pearl production in the world.In traditional farming ponds,H.cumingii is co-cultured with some planktivorous fishes(silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis),and huge amounts of organic manure are used to provide natural food(phytoplankton and detritus)for the mussel and fishes.Excessive fertilization with organic manure results in serious environmental problems.Previous studies found that adding some omnivorous or herbivorous fish species(grass carp Ctenopharyngodon idellus and gibel carp Carassius auratus auratus)in the traditional mussel-fish integrated system and feeding the fishes with formulated feed can enhance pearl yield and growth of mussel.Moreover,pearl yield of mussel is also affected by different fertilization methods(fertilized with fermented duck manure,or chemical fertilizer or both fermented duck manure and chemical fertilizer)when the novel mussel-fish integrated culture is used.In the present study,a 155-day experiment was conducted in land-based enclosures to evaluate the effect of different fertilization method on phytoplankton community in a novel mussel-fish integrated system.Three kinds of fertilizer,including DM(fermented duck manure),CF(chemical fertilizer)and DC(combination of fermented duck manure and chemical fertilizer),were experimented.Each treatment was three replicated,therefore,total 9 enclosures were used.Each enclosure was stocked with 20 mussel,15 grass carp,5 gibel carp,5 silver carp and 5 bighead carp.During the experiment,water samples were collected regularly from the enclosure,and species and biomass of phytoplankton and chlorophyll a(Chl.a)were determined.Results showed that the biomass of phytoplankton ranged from 2.1×10⁸ to 6.0×10⁸ cell/L in the enclosures.No significant differences were found in the species composition and dominant species of phytoplankton,Chl.a,biomass of phytoplankton and ratio of blue-green algae to phytoplankton in biomass among treatments DM,CF and DC.However,fertilization method significantly affected Shannon-Wiener's index and Pielou's index of phytoplankton.Phytoplankton community in the enclosures exhibited an apparent seasonal trend,and concentration of total nitrogen,ammonia and dissolved oxygen were responsible for the alteration of phytoplankton community.The results of the present study could not provide an explanation to the conclusion that pearl yield is higher in treatment DC than in treatments DM and CF.Further studies are needed to explore the linkage between pearl yield and phytoplankton community in integrated culture of H.cumingii and fishes.

Abstract:In order to estimate the dietary Zn requirement of blunt snout bream(Megalobrama amblycephal),Five experimental diets containing different Zn contents of 0,68,137,206,275 mg/kg(total Zn of feed was 22.85,98.07,164.00,235.43,307.96 mg/kg)were for mulated with ZnSO₄·H₂O as the Zn source.A total of 400 blunt snout bream with an initial body weight of 50 g were randomly divided into 5 groups with 4 replicates per group and 20 blunt snout bream per replicate.Each group of fish was fed two diet for 43 days.The results showed as follows:Through regression analysis of relationship between the amount of Zn added to feed,the total Zn of the feed and the SGR,FCR,protein deposition rate,fat deposition rate of the blunt snout bream,when the Zn supplement in the feed was 155.86-161.25 mg/kg(the actual Zn content was 184.85-190.39 mg/kg),blunt snout bream has the best growth performance.In this experiment,the daily feed intake of blunt snout bream was 5.12 g/100 g body weight/d,so the added Zn content of the feed in the 0.798-0.825 mg/100 g weight/d(the total Zn content of the feed was 0.946-0.974 mg/100 g weight/d),blunt snout bream can achieve the maximum growth.The survival rate,fatness,viscera index,scale weight/body weight,body weight/body length,vertebral bone weight/body weight were not significantly affected by dietary Zn content(P>0.05).But in the 0 mg/kg group,vertebral bone length/body length was significantly lower than the 137 mg/kg group(P<0.05);Supplement of Zn is conducive to the growth of the spine of blunt snout bream.

Abstract:A Discriminant Analysis of Principal Components(DAPC)method was adopted to construct a germplasm resource prediction model at individual level,for the sea cucumber Apostichopus japonicus.One hundred and thirty six alleles generated by twenty microsatellite markers were used as the raw data input.Three populations were sampled from Vladivostok,Russia(RS,131.55 E,43.08 N)and Dalian,China(CN1,CN2).Principal Component Analysis(PCA)and Discriminant Analysis(DA)were carried out sequentially.Linear Discriminant functions were constructed with the two China subpopulations as one overall CN population and two separated populations respectively.The results showed that with 75% individuals as training set and the remaining 25% as test set,the accuracy of constructed model reached up to about 80% for the three-pop model and over 90% for the two-pop model.Conventional genetic diversity and genetic structure analysis showed moderate genetic differentiations among the three geographic populations of sea cucumber,and relatively close genetic distances(D₁=0.18,D₂=0.159).Nice accordance of results of conventional analysis and our novel analysis indicated that the current method can be practically well applied on prediction and discrimination on germplasm resource at individual level.To our knowledge,this is the first application of DAPC with molecule marker information to genetic study.The novel method built in the current study can be well applied to the practical breeding project in future.

Abstract:Fatty liver is a physiological or pathological phenomenon and is commonly seen in farmed fish at present.Severe fatty liver in fish results in reduced growth and feed efficiency,impaired immune response and decreased nutritional quality.However,so far,people still don't know exactly the causes of fatty liver in farmed fish,and also have not found good solutions to eliminate fatty liver.The present article systemically reviews the results of fish fatty liver studies and has put forward some new perspectives to discuss the origins of fish fatty liver in the current aquaculture system.In the present review,five main causes of fatty liver in farmed fish are summarized:nutrition and formulated diet,environmental pollution,physiological process,species difference and genetic mutation.Among them,the unbalanced nutrients composition and excess energy intake,such as overfeeding,excess dietary lipid and carbohydrate contents,deficiency of vitamins which are needed to maintain normal lipid metabolism,are regarded as the principal causes of fish fatty liver.Beside,in some aquaculture regions,high amount of water contaminants,especially heavy metals and persistent organic pollutants(POPs),have been recently reported to contribute to the prevalence of fatty liver in farmed fish.The occurrence of fatty liver is also related to the gender and development of fish.For example,the change of fat content in liver of young and/or female fishes normally is more sensitive to dietary energy content than that in liver of older and/or male fishes.It is also noted that some fish species specifically deposit fat in liver,thus fish species difference should be considered in preventing fatty liver in farmed fish.Through reviewing the above results,the present article brings some new perspectives:1)Most of fatty liver could be classified as "nutritional fatty liver" and "oxidative fatty liver"depending on the fatty liver symptom caused from nutrient unbalance or oxidative stress;2)The common occurrence of fatty liver in farmed fish fundamentally correlates with the contradiction between the requirement of high aquaculture production of human and natural physiological features of fish.Therefore,as long as the present fish species have not been genetically modified to adapt to modern high-density aquaculture industry,the common occurrence of fatty liver in farmed fish would last in future for a long time;3)Fatty liver could not be completely regarded as a pathological symptom.Actually,initial stage of increasing hepatic triglyceride synthesis is a protective mechanism to avoid the lipotoxicity induced by high free fatty acids in circulation.In conclusion,feeding fish with optimal nutrients-balanced diets,keeping freshness of feed and raw feed materials,and maintaining a sustainable healthy water environment are the ultimately right measures to prevent fish fatty liver.

Abstract:The full-length cDNA encoding growth hormone(GH)was isolated from the pituitary of Platichthys stellatus using RACE(rapid amplification of cDNA ends)method.Results showed that Platichthys stellatus GH cDNA sequence is 957bp in length and encodes 204 amino acids.The highest amino acid identity of Platichthys stellatus GH was 73.0% with Paralichthys olivaceus.Phylogenetic analysis indicated that Platichthys stellatus GH was clustered with other pleuronectiformes and perciformes species.The tissue expression patterns of GH mRNA in different tissues of female and male adults were analyzed by the quantitative real-time PCR.GH mRNA showed the highest expression level in the pituitary of both sexes with lower levels in the brain,gonad,liver,stomach and muscle.The expression levels of GH mRNA in the female stomach and muscle were significantly higher than those of males(P<0.05),which implied that it might be involved in sexually dimorphic growth pattern through paracrine and autocrine pathways.The GH/pET28a recombinant plasmid was successfully constructed and highly expressed in E.coli BL21(DE3)after being induced by IPTG with special fusion polypeptides containing His6 at their N-terminus.The obtained recombinant GH polypeptide was expressed in form of inclusion bodies with molecular weight of 24.9 ku and had the antigenicity to His6 antibody by western blotting analysis.The inclusion bodies were denaturalized using 6mol/L guanidine HCl,purified using Ni²⁺-NTA affinity chromatography and annealed by gradient dialysis in urea,and the verified recombinant GH protein was obtained.The effect of recombinant GH protein on proliferation of human embryonic kidney cells HEK293T was tested,and the results showed that significant inhibition was only found when protein concentration was higher than 5.4 μg/mL.Results from the present study could provide basic knowledge for molecular-level and protein-level growth regulation mechanism study of Platichthys stellatus.

Abstract:A 12-week growth experiment was conducted to quantify the optimum dietary pantothenic acid(PA)requirement of GIFT tilapia Oreochromis niloticus.Triplicate groups of experimental tilapia with initial body weight[(79.4±1.6)g]were cultured in 500 L aquaria(r=0.9 m,h=0.75 m;15 fish each aquarium)and fed with the experimental diets at six levels(0.5,4.8,9.5,18.2,36.3 and 74.4 mg/kg diet,respectively)of PA(supplied as Calcium d-PA).The results showed that,with the increasing of dietary PA level,weight gain rate of tilapia first increased linearly,then remained nearly unchanged at high PA treatments.Hepatic and muscle PA contents presented the same tendency with weight gain rate.Condition factor and hepatosomatic index first increased,then decreased with the increase of dietary PA level,and they were highest in 4.8 mg/kg PA supplement group.Whole body moisture content of tilapia first decreased,then increased as dietary PA increased,while whole body crude lipid content presented an opposite tendency.Hepatic total lipid concentration significantly decreased,the supplement groups showed significantly lower values than that in the un-supplemented group(P<0.05).The increase of dietary PA level also significantly increased serum high density lipoprotein cholesterol content(P<0.05).Broken-line regression analysis showed the optimum dietary PA requirement of GIFT tilapia was estimated to be 10.5 mg/kg for maximum growth,12.6 and 13.5 mg/kg for maximum hepatic and muscle PA concentration,respectively.

Abstract:Rice-based production system with the mixture of cropping and aquaculture is a traditional agriculture system in China.With the development of modern agriculture,it is becoming a popular food production pattern around China.Because rice-based production system could maintain the riceland biodiversity and reduce the production cost,Chinese government encourages the development of these coculture systems.Based on the local tradition and habit of cropping and aquaculture,there are two dominant coculture types:Rice-crab and rice-fish systems.However,to date,the cost,benifit and productivity per unit of these coculture patterns varied from farmer to farmer as well as from area to area,which indicated the rice-based production system is still immature and unstable.Therefore,based on the survey of rice-based production system from four typical provinces in 2013,we investigated the current status of two major rice-based production systems in China.In this study,the production inputs,economic benefits,fertilizer and pesticide utilization were analyzed and compared to provide the useful information for the future development of rice-based production system.The results are as follows:Compared to the rice monoculture,these two rice-based production systems have higher average profits(2.43-3.92 times),lower fertilizer and pesticide cost(reduced by 2.8%-49.2% and 3.2%-83.6% respectively).These results indicated that both rice-crab and rice-fish coculture systems had better economic and ecological benefits than rice monoculture system.But due to the technical immaturity and degree of industrialization,huge differences were observed on the final economic and ecological benefits among the farmers.This investigation revealed that the small scale,the high cost of inputs,limited ecological and social benefits are the main problems we are currently facing in the rice-based production systems.In conclusion,our results suggested further development of key technology,increasing the governmental support,and improvement of production scale are very important to slove these problems.

Abstract:Sargassum vachellianum C.Agardh is native to China and mainly distributed in coastal waters of Zhejiang,Fujian,Guangdong and Hong Kong,China.It is important in maintaining the structure and function of littoral ecosystems and has been chosen as the main candidate for seaweed bed reconstruction by artificial breeding in China.Thus,to conserve and sustainably use this species,we should make genetic studies on it.As the traditional classification and phylogenetic relationships in Sargassum have been challenged by DNA phylogenies and the status of numerous species have been re-assessed,it is necessary to know whether the traditional taxonomy of S.vachellianum needs to be revised.However,there was no DNA markers have been reported in this important species.In this study,we cloned and sequenced ITS sequences of 15 S.vachellianum individuals from 3 different geographic populations.As a result,4 different ITS sequences were obtained.Sequence analysis revealed that the lengths of the four ITSs were all the same and their ITS1,5.8S and ITS2 were 762,158,and 507 bp,respectively.There were 3 mutations among the four ITS sequences,but no geographic population specific sites were found.The phylogenetic relationships among the four S.vachellianum ITSs and 24 GenBank ITS sequences from three genera of Sargassaceae were studied with sequences from Hizikia fusiformis,Turbinaria conoides and T.decurrens as three outgroups.The Neighbor-Joining phylogenetic tree constructed by MEGA 4.0 showed the four ITSs of S.vachellianum were clustered together first and then clustered with S.sp. and S.piluliferum,indicating a close genetic relationship corresponding to the smallest genetic distance(0.004)between S.vachellianum and S.sp.The greatest pairwise genetic distance(0.422)existed between S.vachellianum and T.conoides.

Abstract:As the residue of defatted microalgae,Chlorella co-products were still rich in nutrient component.If the residue wasn't rationally utilized,it would not only become a waste of resources,but also cause environmental pollution.Some researchers are very conscious of the problems involved.Although they focused on protein content of the co-products,there was few detail to deal with it.This study researched on whether Chlorella co-products could replace soybean meal or fish meal in the diet of Litopenaeus vannamei. Six isonitrogenous and isoenergetic feeds were formulated and fed to white shrimp with initial weight(5.02±0.73)g for 45 days.The feeds contained 0%,6%,11%,16%,21% co-products to replace soybean meal respectively; and contained 8% co-products to replace fish meal.The six feeds were also named control,A1,A2,A3,A4 and B groups respectively.The results showed that group A3 had lower survival rate compared with control.There were no significant differences in weight gain rate and specific growth rate among group A2,A4 and control.Feed Coefficient Ratio in group A3 was the lowest compared with other groups.Protein efficiency ratio in A3 was the lowest and group B was also lower than other groups.No significant differences were found in muscle protein contents among all groups,while total phosphor contents in all replacement groups were higher than control,and group A4 was the highest.Total amino acids and total essential amino acids were first increased and then decreased,group A3 was the highest; total nonessential amino acids of control were lower than groups A1,A2 and A4.Protease activity of intestine in control was higher than other groups except group A1; but group A2 had higher lipase activity and groupA4 had lower amylase activity of intestine.In hepatopancreas,group A1 had a lower protease activity,and no significant differences among other groups.Lipase activities of all groups were higher than the control,and the A3 was the highest.Amylase activities of all groups were lower than control except A3.There were no significant differences between any groups on respiration of shrimp.The trend of nitrogen excretion was first increased and then decreased,group A3 was the highest.Phosphorus loading rates in all replacement groups was not higher than control group; nitrogen loading rate in group A3 was the higest, and that in all other replacement groups was not higher than control group.It is concluded that in view of growth performance,and nitrogen and phosphorus loading,feed containing 10% co-products to replace soybean meal which decreased to 11% from 19% may suit L.vannamei.

Abstract:Experiments were carried out to investigate the burrowing ability of juvenile ark shell Anadara broughtonii(2-3 cm shell length),and the predation rate on juveniles by sea star(Asterias amurensis)at different seawater temperatures(10,15,20,25 and 30 ℃,respectively).The results showed that A.broughtonii had the longest burrowing time(28.87 min)and the lowest burrowing rate(21.25%)at 10 ℃,which were significantly different from other temperature treatments(P<0.05).The shortest burrowing time(7.49 min)and the highest burrowing rate(55.63%)were observed at 20 ℃,suggesting that 20 ℃ was the suitable burrowing temperature.The predation rate at 20 ℃(5.28 ind/d)was significantly higher than those at 10 and 25 ℃(P<0.05).The optimum predation temperature was between 15 and 20 ℃ and the Q₁₀ coefficient for A.amurensis was 2.22 in that range.The overlap of the optimum temperature range was observed for A.broughtonii burrowing and preyed by A.amurensis,suggesting that protective strategies for juvenile A.broughtonii are needed when the water temperature is close to 20 ℃.

Abstract:The utilization of carbohydrate in fish seems low compared with terrestrial animals,with intolerance to hyperglycemia,but the glucose regulation mechanism does exist in fish.In order to update the studies on glucosensing and carbohydrate metabolism in fish,and provide basic information for getting a better understanding about these physiological mechanisms,this review briefly introduced the progress of research on glucose sensing and its relationship with appetite,and the regulation of glucose metabolism in fish.The piscine glucose sensors were located in the different parts of the body,including central nervous system(CNS)and peripheral tissues.It is worth noting that both the glucose sensors and appestat are located in the hypothalamus,and they are also both regulated by some endocrine factors,such as leptin,ghrelin,cholecystokinin(CCK),neuropeptide Y(NPY),and so on.In mammals,the glucose sensing and appetite regulation were linked by AMP-activated protein kinase(AMPK)and mammalian target of rapamycin(mTOR)signaling pathways.Although this link has not been identified yet in fish,it was found that the energy state or some endocrine factors of fish were highly related with AMPK or mTOR phosphorylation levels.Probably this link was presumably similar to that in mammalian.In addition,the blood glucose levels of fish were regulated by some endocrine factors such as insulin,glucagon-like peptide-1(GLP-1),ghrelin,CCK,NPY,somatostatin(SS),etc.Besides,the glycometabolism and utilization in fish was aslo regulated by dietary nutrients including carbohydrate,lipid and protein.High-carbohydrate diet increased the activity and mRNA expression of glucose kinase(GK)in the liver of fish,and the glycolysis were also strengthened,even in the early development.Moreover,the hepatic gluconeogenesis in omnivorous species was inhibited by high-carbohydrate diet,but unaffected in carnivorous.Furthermore,High-fat diet promoted the glycolysis in some species,and the gluconeogenesis was also promoted both by high-fat and high-protein diets.However,there are still some questions that need further research.Finally,the development tendency and research hotspot in the carbohydrate metabolism of fish were discussed.For example,how the CNS integrate the nutritional,endocrine and other signals to regulate food intake in fish? what is the mechanism behind the differences between herbivorous,omnivorous and carnivorous species in glucose tolerance and the regulation of hepatic gluconeogenesis,etc.

Abstract:Alkaline phosphatase(ALP)is a widely-distributed phylogenetic phosphomonoesterase involved in the precise regulation of the animal biological metabolism.In this study,an ALP gene,LcALP,was cloned for the first time from Larimichthys crocea. Its full-length cDNA sequence is 2 345 bp,with a 1 629 bp open reading frame encoding a protein of 543 aa.qRT-PCR revealed the expression of LcALP could be detected in all adult tissues examined,with higher expression in the eye and head kidney of both sexes.Compared with the male,the expression level of LcALP gene from female was significantly higher in the gill and brain whereas much lower in the gonad and spleen.The low levels of LcALP were observed during the multiple cells,blastula,and gastrula stages.The levels increased significantly at yolk plug stage and peaked at prehatching stage,and then declined obviously at the alevin stage.After treatment with LPS,the expression level of LcALP in muscle cell line began to decrease at 6 h and was down-regulated significantly at 12 h.When large yellow croaker muscle cell lines were treated with poly I:C,the expression level of LcALP continuously increased to the peak at 24 h.Our results suggested that LcALP might play important roles as a regulator during the embryonic development and as an immune factor under stimulation of different pathogen-associated molecular patterns.

Abstract:There is a special fat cavity in the dorsum of ayu(Plecoglossus altivelis),but no studies have been reported on morphology,structure and composition of the unique fat cavity so far.This study observed the anatomical morphology,microstructure and analyzed the composition of ayu fat cavity.The results showed that the fat cavity of ayu was fusiform and extends from supraoccipital bone to adipose fin,the shape of cross-section exhibits as an inverse-triangle.The weight and length of the fat cavity were(1.95±0.86)g and(9.17±0.82)cm respectively,which account for 4.96% and 53.22% of the total weight[(39.31±5.12)g]and total length[(17.23±0.72)cm]of the fish.In the fat cavity,there were top and down glands,muscles,undifferentiated mesenchymal cell,adipose tissue,and microvasculars.The main components of fat cavity were crude fat(49.10%),water(42.4%),crude protein(6.8%)and ash(1.13%).The percentage of fatty acid was 34.266%,which contains 5 kinds of saturated fatty acid and 6 kinds of unsaturated fatty acid.The highest and lowest fatty acids are palmitic acid(11.800%)and lauric(0.022%)respectively.The total percentage of amino acid was 7.1%,in which the highest content was glutamic acid(1.18%)and the lowest content was methionine(0.10%).This research provided biological basis data for investigating of the fat cavity function,occupy-territoty habit and potential medicinal value.

Abstract:This study compared photosynthetic characteristics on the tip,middle,base of juveniles Sargassum thunbergii.Parameters analyzed included:net photosynthetic oxygen evolution rate(P_n),dark respiration rate(R_d),rapid light curve and fluorescent dark relaxation parameters.This was determined using both a liquid-phase oxygen electrode system,and pulse amplitude modulated fluorometry.In addition,the growth rate of juveniles was measured by weight,and its relationship with photosynthesis was discussed.The formation of vesicles was observed.The results show that:(1)P_n and Rd in the tip were higher than those in the middle and base(P<0.05).(2)In the low light(LL)adapted samples there was a delay in photosynthesis,and PSⅡ was immediately inhibited if the samples were put in light conditions.However,medium light(ML)conditions showed photochemical reactions and heat dissipation to be in balance.In high light(HL)conditions electric transport rate(ETR)was near saturation,and non-photochemical quenching(NPQ)was higher than LL and ML conditions.It was also observed that under HL conditions ETR_max in tip and middle of the juveniles was higher than that in the base(P<0.05).(3)For LL and ML adapted samples,NPQ recovery was fast,whereas in HL it was slow.Under all light levels(LL,ML,HL)in the samples tip,NPQ recovered rapidly and completely to 0.This indicates highly efficient restoration in the tip,but not in the middle and base where photodamage may be occurring.(4)Under ambient light levels pigment content was higher in the tip than that in the middle and base,and Chlorophyll a contents were higher than carotenoid in the tip,which was contrary in the middle and base.(5)The specific growth rate values relative to position on the algae were as follows:tip >middle >base(P<0.05),indicating fast organic matter accumulation in the tip.It was observed that in increased temperature conditions,small gaps which formed in the narrow leaf tip developed into vesicles.This suggests that temperature is the main inducing factor for the formation of vesicles.The results of this study suggest that photosynthetic rate,growth rate,and recovery capability in the tip of juvenile S.thunbergii may be higher than those in the middle and base.

Abstract:Previous studies suggested that the coelomic fluid or hemolymph from different aquatic invertebrates had different antibacterial spectrum and capacity,and bacterial disease is one of the primary factors limiting the development of Apostichopus japonicus aquaculture.To control the bacterial disease in A.japonicus with the immunological methods,understanding the antibacterial characteristics of coelomic fluid is necessary.However,the information about the antibacterial characteristics of coelomic fluid is limited in A.japonicus.Besides,the gradient dilution plate count method and turbidimetric method used for antibacterial analysis in previous studies are just suitable for the determination of bacteriolytic activities rather than the antibacterial activities consisting of bacteriolytic activities and bacteriostasic activities,while the method of bacterial growth curve determination,applicable to the determination of antibacterial activities,was not broadly employed.Therefore,in order to study the antibacterial spectrum of coelomic fluid from A.japonicus and the effects of divalent metal ions on the antibacterial activities of coelomic fluid,using the method of bacterial growth curve determination,we determined the effects of coelomocyte lysate supernatant and coelomic fluid supernatant from A.japonicus on the growth of Vibrio harveyi,Vibrio splendidus,Shewanella baltica,Pseudoalteromonas nigrifaciens,Staphyloccocus aureus,Micrococcus lysodeikticus,Streptococcus dysgadysgalactiae, Nocardiopsis sp.,respectively,and then determined the effects of Fe²⁺,Ca²⁺,Cd²⁺,Mg²⁺,Mn²⁺ and Zn²⁺ commonly found in marine environment on the antibacterial activities in A.japonicus coelomic fluid supernatant with M.lysodeikticus as tested bacteria.The results showed that the coelomocyte lysate supernatant had no obvious effects on the growth of all tested bacteria,while the coelomic fluid supernatant only showed strong inhibition on the growth of M.lysodeikticus.In addition,Mg²⁺ and Zn²⁺ increased the inhibition of coelomic fluid supernatant on the growth of M.lysodeikticus,while Fe²⁺,Ca²⁺,Cd²⁺ and Mg²⁺ showed no obvious effects on the antibacterial activities of coelomic fluid supernatant.The results above suggested that A.japonicus coelomic fluid in vitro only had limited-spectrum antibacterial activity,and the immune factors directly related to anti-bacteria were mainly distributed in coelomic fluid supernatant.Besides,these antibacterial factors in coelomic fluid supernatant developed a certain adaptability to the divalent metal ions that are commonly found in marine environment,and at certain concentrations,Mn²⁺ and Zn²⁺ might be beneficial to the promotion of A.japonicus antibacterial capacity.

Abstract:Decreasing global availability of fish meal or fish oil has urged the aquaculture industry to investigate the alternative ingredients.Exploring the dfferences between fish meal or fish oil and their substitution is particularly important.And one of the main differences is whether highly unsaturated fatty acids(HUFAs)exist and their content.HUFAs are the fatty acids that contain no less than 20 carbon atoms and 3 double bonds,which play important roles in supplying energy for fish organism,moderating the membrane compositions,converting to the highly biological eicosanoids,as well as regulating the lipid metabolism and immune response,mainly being contained in fish oil and certain kinds of microalgae.It is acknowledged that freshwater fish has the capacity to synthesize HUFAs de novo,thus HUFAs were not the essential fatty acids and there is no need to be included in the diets.However,considerable researches have proved the nutritional benefits of HUFAs in the freshwater fish,suggesting that the fatty acid theories of freshwater fish remained to be further improved.This paper reviewed the recent results about the effects of HUFAs on the growth performance,lipid metabolism,health status,immunity and reproductive performance of the freshwater fish,indicating that HUFAs should be supplied in diets for the cultured freshwater fish,especially in the context with the use of less-HUFAs-contained protein or oil sources.The role of dietary HUFAs for freshwater fish should be noted in the future studies.Finally,the prospects of future research on HUFAs requirement of the freshwater fish as well as new HUFA-enriched oil source development have been discussed.

Abstract:To identify temporal-spatial distribution of fish resources in Zhejiang coastal and estuary regions,based on the data from bottom trawl fishery resources in Taizhou Bay in April and October 2010,The temporal and spatial distribution and the influence of dominant species,temperature and salinity,water depth and other factors on the amount and distribution of fish resources were analyzed.The result showed that the change trends of individual densities and weight densities were consistent,In April,both of individual densities and weight densities were higher than those in October in terms of seasonal distribution.In the spatial distribution respect,the fish resources densities in the north studied area were obviously higher than those in the south in April,however,it was obviously opposite to October.According to stepwise regression analysis of fish resource density with dominant species and hydrological factors,in two seasons,the variation of resource density had significant correlation with all the dominant species,Harpodon nehereus is the most dominant species because of its highest contribution rate to the weight densities and Individual densities.Meanwhile,the fish resource density had significant correlation with surface temperature(P_W=0.001,P_N=0.009),and depth had insignificant correlations with resource density(P_w=0.067,P_N=0.051).The area whose depth was less than 20 m had higher amount of fish resources density in Spring,while the high values of density at greater than 20 m depth in Autumn.This research showed that the fish resources had a significant seasonal alteration and spatial variation.Bottom water temperature was the most important factor that affected variations in the fish resources in the Taizhou Bay.

Abstract:The transcriptome of the Huso dauricus' muscle tissue was sequenced by a new generation of high throughput sequencing technology in order to fill a gap which has hitherto existed in the research field of gene sequences of H.dauricus and to preserve the gene resources,at the same time to lay the ground for discovering functional genes and cloning new genes,etc.Obtaining 14 447 211 200 bp of the original data,it generated 55 531 Unigenes which ranged from 300 bp to 32 613 bp in length,the average length was 941 bp.Similar searches were made by Bioinformatics methods which was against the Nr database of these Unigenes,in addition,it made gene functional description of the GO and analysis of metabolic pathways of KEGG.The result indicated that 20 735(37.34%)of these Unigenes have significant matches.The unigenes GO functions in the transcriptome library were divided into 3 categories:biological process,cellular component and molecular function with 56 branches;it could be divided into 290 classes taking the KEGG database as a reference.

Abstract:In order to develop new germplasm of Pyropia,the wild-type strain(PC-WT)of Pyropia churharii from India were treated with ⁶⁰Co-γ ray to induce mutations,and then the new strains(PC-Y1 and PC-Y2)with advantages in growth and quality were obtained.The PC-WT was characterized by slow growth and releasing archeospores excessively.One of the new strains was PC-Y1 with the characterizations of slender blade,rapid growth and almost releasing no archeospores.The other was PC-Y2 with the characterizations of wide blade,fast growth and a few archeospores releasing.When the blades of PC-WT,PC-Y1 and PC-Y2 were cultured for 55 days,their mean lengths were 5.31 cm,91.30 cm and 15.26 cm,respectively,indicating that PC-Y1 and PC-Y2 grew significantly faster than PC-WT.In the 45-days-old blades of PC-WT,PC-Y1 and PC-Y2,the contents of chlorophyll a(Chl.a)in PC-Y1 and PC-Y2 were obviously higher than that of PC-WT;and the contents of phycobiliprotein(PE+PC)in PC-Y1 and PC-Y2 were 119.32 mg/g and 102.29 mg/g,respectively,which were 2.74 times and 2.35 times higher than those in PC-WT,respectively.Thickness of the 45-days-old blades of PC-Y1,PC-Y2 and PC-WT was 20.86 μm,27.98 μm and 32.48 μm,respectively,which showed that both PC-Y1 and PC-Y2 were significantly thinner than PC-WT.The quantities of the released conchospores of PC-Y1,PC-Y2 and PC-WT,were 1.011 6,1.434 4 and 1.751 7 million per shell,respectively.Furthermore,the PC-Y1 was superior to wild-type strain of Pyropia haitanensis in high-temperature(29 ℃)resistance.These results indicated that the characterizations of PC-Y1 and PC-Y2 were similar to those of Pyropia yezoensis,including thin gametophytic blades,good quality and archeospores releasing;in addition,compared with Pyropia haitanensis,PC-Y1 strain had better resistance to high-temperature,releasing more conchospores,higher growth rate and late maturation.Therefore,PC-Y1 strain had great potential to be applied in commercial cultivation.

Abstract:To study the effect of Vibrio parahaemolyticus challenge on the non-specific immune function of Penaeus monodon,healthy P.monodon[average body weight(5.65±0.34)g]were used to determine the changes of non-specific immune enzyme activities in hepatopancreas and gill tissues after being injected with sterile 0.86% normal saline and V.parahaemolyticus.Activities of total antioxidant capacity(T-AOC),acid phosphatase(ACP),alkaline phosphatase(ALP)and lysozyme(LSZ)were measured at different sampling time points.The results showed that:compared with the control group,after being challenged with V.parahaemolyticus,T-AOC activities in hepatopancreas and gill were both increased to the peak value at 12 and 6 h(P<0.05),respectively,and then decreased gradually.ACP activities in hepatopancreas were up-regulated significantly at 3 h(P<0.05),then decreased gradually and reached the lowest level at 24 h(P<0.05).In gill,ACP activities were increased to the maximum at 12 h,and then decreased gradually to a lower level than the control at 48 h(P<0.05).ALP activities in hepatopancreas and gill both showed a downward tendency after rising first in general,but did not exhibit the phenomenon of significantly lower than the control group.LSZ activities in hepatopancreas and gill both increased significantly to the peak level at 3 h,and then returned to the control group level gradually.The results indicated that V.parahaemolyticus challenge had noticeable impact on non-specific immune enzyme activities of P.monodon,and significant destructive effect to the shrimp's immune system.

Abstract:The sparid fishes are one of the most economically important marine fishes in the world.However,the classification and phylogeny of Sparidae have been long confused due to the high diversity of morphological characters.The present paper deals with the comparative osteology in eight species pertaining to five genera of Sparidae collected from Chinese coastal waters by conventional method.The results indicate that the family Sparidae is divided into two groups on the basis of the comparative anatomy and morphology of urohyoid,premaxilla,mesethmoid,sphenotic,circumorbital series and palatinum.The two genera Rhabdosargus and Acanthopagrus are grouped in one clade,and the three genera Pagrus,Evynnis and Dentex are grouped in another clade.There is a subtle difference between Pagrus and Evynnis in the characters including number and patterns of molariform teeth on both jaws,the third circumorblital,the palatinum and opisthotic.There are no obvious differences in osteological characters between P.auratus and P.major.The present results suggest that these two species,P.auratus and P.major,did not show enough morphological divergences to be classified as different species.We support partly the findings of Paulin that these two species should be treated as a single species named P.auratus,because P.auratus is the senior synonym of P.major.Similarly,the present results also suggest that the relationship between A.schlegelii schlegelii and A.schlegelii czerskii is at the level of a single species named A.schlegelii.These characters of skeletons can be used as important basis for identifying genera or species.

Abstract:Common carp(Cyprinus carpio)is one of the most widespread freshwater teleost species in the world.It has been cultured as an important food fish worldwide,especially in China,for several thousand years.In the past decade,much research efforts have been made for the molecular breeding of common carp including development of polymorphic markers,linkage mapping,and quantitative trait loci(QTL)analysis.However,QTL researches of common carp have been limited by single family and small population size.Considering the ability to detect and identify QTL in single family is often limited and has obtained false positive locus.We conducted a whole genome scan on 522 progeny from 8 full-sib families using 250 microsatellites selected from high density genetic linkage map of common carp constructed by our lab.The genetic maps were constructed by use of the Cri-map program with genotypes of 8 families,and genetic distances were estimated by use of the Kosambi map function.A total of 233 markers were organized to 47 linkage groups and the linkage maps covered a genetic distance of 3 131.5 cM,with the average interval for markers within linkage group of 16.8 cM.The linkage map could be used for primary QTL analysis.QTL identification of standard length(SL)and body weight(BW)traits was carried out using half-sib mapping strategies by GridQTL software.We obtained 4 QTL distributed across 3 linkage groups(LG)during sire-based QTL analysis.For SL,3 QTL were identified,of which 1 QTL occurred at the 95% genome-wide level,and was located on LG24,accounting for 20.3% of phenotype variation.The remaining 2 QTL were at the 95% chromosome-wide level,explaining 11.9%(LG6)and 11.6%(LG30),respectively.For BW,1 QTL was identified at 99% genome-wide level,explaining 38.3% of phenotypic variance and overlapped with the SL QTL intervals on LG24.During dam-based QTL analysis,we identified 8 QTL that were distributed across 5 LGs.Five QTL were associated with SL,of which one was at 99% chromosome-wide level and located at LG8.The other 4 QTL were at the 95% chromosome-wide level,accounting for 9.6%-20.3% of phenotypic variance.QTLs on LG24 and LG30 were significant both the sire and the dam-based analysis.For BW,three QTL were detected and have a similar confidence interval with SL at LG24,LG30 and LG45.Among these,2 QTL were identified at the 99% chromosome-wide level,and 1 QTL at the 95% chromosome-wide level,explaining 10.8%-14.1% of phenotypic variance.The results showed that the most significant QTLs for SL and BW were located on LG24 and common to both sire and dam.The results of this study not only can supply more reliable markers for molecular breeding of common carp,but also provide reference data for exploring regularity of QTL variation among different populations and families.

Abstract:Intestinal microflora play an important role in animal development and health.In order to evaluate the changes of the bacterial communities in fish intestine upon diseases occurrence,the diseased Cynoglossus semilaevis cultured in two indoor farms with ascites and skin ulceration,and healthy fish in the same farming system were studied by using high through sequencing technique in this paper.The results revealed that bacteria species in fish intestine were obviously less than those in environment,only accounting for 14.3%-44.7% of the bacteria species in pellet feed or tank inlet water.After disease occurrence,the bacteria diversity in diseased fish intestine declined markedly,just 45.8% and 64.5% of the bacteria species in healthy fish coming from the same farming system.For further analysis of these microbial communities structure,although more than 60% bacteria species were different between diseased fish and healthy fish,the dominant bacterial communities' structure in these fish intestine had almost no difference.The first ten dominant bacterial strains in each fish sample were basically the same,their total proportion exceeded 80% of the relative bacteria amount in fish intestine.We also found that different disease occurrence had different effects on half-smooth tongue sole intestinal microflora.The microbial community structure in diseased fish intestine with ascites changed distinctly,while the fish with skin ulceration hardly changed.According to the results of this study,the microflora in cultured half-smooth tongue sole intestine was conservative.But not every type of disease can cause this micro-ecosystem structure change.

Abstract:In order to suppress C.turgidus growth during the amplification process of filaments of S.lomentaria,the effects of five commonly used antibiotics:streptomycin(Str),ampicillin(Amp),kanamycin(Km),gentamicin(Gm)and chloramphenicol(Cm)on the growth of filaments of S.lomentaria and C.turgidus,which were co-cultured in the research were studied by experimental ecology methods in this paper.Results indicated that:(1)Str inhibited the growth of C.turgidus significantly at the concentration of 100 μg/mL,while filaments of S.lomentaria were not affected;(2)Amp and Gm had obvious inhibitory effects on the growth of C.turgidus at the concentration of 100 μg/mL,and filaments of S.lomentaria were inhibited at concentrations of 100 μg/mL and 500 μg/mL respectively;(3)The growth of the filaments of S.lomentaria was not suppressed by Km within the set range of concentration in this research,while 10 μg/mL Km inhibited C.turgidus intensively;(4)Both filaments of S.lomentaria and C.turgidus were particularly sensitive to Cm,the growth of C.turgidus was inhibited by 10 μg/mL Cm distinctly and filaments of S.lomentaria were also suppressed when the concentration of Cm reached 10 μg/mL.The results mentioned above revealed that Str(100 μg/mL),Km(100 μg/mL)and Cm(10 μg/mL)could be applied to reduce the risk of contamination of C.turgidus during the preservation and amplification of filaments of S.lomentaria.

Abstract:Nervous necrosis virus(NNV)can cause mass mortalities of many marine and freshwater fishes in the world.The genome of NNV consists of two segments,positive sense,single strand RNAs,named RNA1 and RNA2.A sub-genomic RNA3 is synthesized during virus replication.RNA1 encodes RNA-dependent RNA polymerase;RNA2 encodes capsid protein,the only viral structural protein,while RNA3 encodes B1 and B2 proteins,which are non-structural viral proteins.Based on the gene of the capsid protein,NNV are classified into four genotypes,named striped jack nervous necrosis virus(SJNNV),tiger puffer nervous necrosis virus(TPNNV),barfin flounder nervous necrosis virus(BFNNV)as well as red spotted grouper nervous necrosis virus(RGNNV).However,there are only A,B and C three serotypes of the virus,in which SJNNV belongs to A serotype,B belongs to TPNNV,BFNNV and RGNNV belong to C serotype.There are vertical and horizontal transmission pathways of the virus and it is widely distributed in wild-ranged and cultured fish.Blocking the transmission of the virus between wild and cultured fish as well as the development of novel vaccine will be the trend of the virus research in the future.

Abstract:This experiment was to study the genetic structure of E.awoara,which could realize effective resource conservation and sustainable use of this species.PCR was used to amplify the complete sequences of the mitochondrial DNA(mtDNA)D-loop region of 53 individuals of E.awoara collected from Dongshan Bay.Because 5' end contained different numbers of repeat sequence units(RSU)and D-loop region had base insertion or deletion,sequences length of 53 E.awoara individuals ranged from 956 bp to 1 230 bp.53 E.awoara individuals were divided into three groups:2RSU(11.3%),3RSU(77.4%),4RSU(11.3%).Sequences were analyzed with the MEGA(version 3.0)and DnaSP(version 4.0)softwares.The results showed as follows:The average content of T,C,A and G was 33.4%,17.3%,35.4% and 13.9%,respectively.179 polymorphic sites were detected yielding 53 haplotypes.The average genetic distance of haplotypes is 0.019 7.The haplotype diversity was 1.000(H_d).The nucleotide diversity was 0.017 2(π).It is concluded that the genetic diversity of the E.awoara population in Dongshan Bay was at a medium level in mitochondrial DNA control region sequences.

Abstract:Infectious spleen and kidney necrosis virus(ISKNV)is the causative agent causing high mortality and significant economic losses to Chinese perch and it is listed by OIE.Now an effective virus inactivated vaccine has been developed and it is necessary to determine virus titer in vaccine development process.Because the traditional cytopathic effect(CPE)method is time-consuming and laborious,it is essential to establish a rapid,accurate method for testing ISKNV titer.The development and validation of a TaqMan qPCR assay for determination of ISKNV titers were reported in the present study.This method used specic primers and probe designed to amplify a small genomic fragment of ISKNV 007 gene.The method was specific and reproducible as well as sensitive with the minimum detectable limit of 10 viral copies.At the same time cytopathic effect(CPE)method was compared and analyzed to qPCR.The results showed that the titers obtained by qPCR correlated well with TCID₅₀ as indicated by linear regression and linear equation was y=1.076x+0.545(R²=0.998 6).Y stands for Log gene copies concentration and X stands for Log TCID₅₀ of virus.The results showed that the real-time PCR method can replace the CPE method in evaluating the titer of ISKNV vaccine,which will shorten vaccine producing cycle and provide convenience for vaccine production.

Abstract:In order to understand the species composition and abundance distribution pattern of fish eggs and larvae in the East China Sea ecosystem and their relationship with physical environmental factors,based on the data of five ichthyoplankton and physical environment surveys in the East China Sea in different seasons during November 2006 to June 2008,the seasonal and inter-annual variation of species composition and abundance distribution pattern of fish eggs and larvae,and the seasonal and inter-annual variabilities in physical environment of spawning grounds and their impacts on the distribution pattern of the spawning grounds,species composition and abundance distribution patterns of fish eggs and larvae have been discussed.The result showed that a total of 74 813 fish eggs and 16 826 fish larvae belonging to 135 taxa were collected,of which,109 taxa have been correctly identified to species level,which belong to 99 genera,67 families and 15 orders;while 17 taxa can only be identified to genus level,6 taxa only identified to family level and 3 taxa identified to order level.There was a tendency toward increased species number and amount of fish eggs and larvae from autumn,winter to spring during 2006 to 2007;whereas,the species number and amount of fish eggs and larvae for samples collected in spring 2008 were significantly lower compared to those collected in spring 2007.Though the species number of fish eggs and larvae for samples collected in spring 2008 were almost the same as in early summer 2008,the amount of fish eggs were significantly larger in early summer compared to spring,on the contrary,the amount of fish larvae in early summer were almost the same as in spring 2008.Species composition of the forty-two dominant species,important species and main species are the major components of fish eggs and larvae distributed in the East China Sea currently.Studies of the physical environment in the East China Sea showed that changes in patterns of sea surface temperature and salinity were markedly different among seasons.In the research domain,the order in which the sea surface thermal front intensity varied with seasons from the strongest to the weakest was autumn-winter,spring and early summer;the distance from the frontal areas to the coastal also varied with seasons from the nearest to the farthest was autumn,winter,spring and early summer,meanwhile the frontal areas run southward in winter and run northward in summer.The sea surface saline front mostly lies close to the shore and usually runs parallel to the shoreline.The surface saline front intensity varied with seasons,most visible in winter,whereas some wane in early summer before regaining strength in autumn.The autumn-winter water temperatures in deep shelf sea areas were higher than coastal waters,and then the spawning stock moved to offshore deep-warm waters and spawned there.The water temperature in coastal waters remarkably increased in spring and the highest value was recorded in the early summer.Then the spawning stock exhibited some form of an inshore spawning migration,and the spawning ground expanded from deep shelf sea areas to coastal waters and formed inshore spawning centers.The abundance distribution patterns of the fish eggs and larvae were closely related to the surface thermal and saline fronts,also species-specific temperature-salinity tolerance.In general,fish eggs and larvae were distributed according to the spreading of the warmer surface waters and gathered at the warm side of the thermal front,with species-specific optimal temperature-salinity.Ocean environmental conditions such as temperature and salinity,and the reproductive biology of each species were the main causes of variation in species composition and distribution patterns of fish eggs and larvae among different surveys.Optimal temperature-salinity range,convergence and entrainment in the frontal area and the biological characters of the species all play the importand role in the formation of high density areas of fish eggs and larvae.

Abstract:An 8-week feeding trial was conducted to evaluate the effects of different dietary protein and carbohydrate levels on the nutritional composition and texture of dorsal muscle.Six experimental diets were formulated to contain two protein levels(41.0%,37.5%)and three carbohydrate levels(taking wheat flour as carbohydrate source,the content of wheat flour was 19%,24%,29%),named L1(19/41),L2(24/41),L3(29/41),L4(19/37.5),L5(24/37.5)and L6(29/37.5),respectively.Taking black sea bream as the test object fish[mean initial body weight was(9.95±0.22)g],at the end of feeding trial,dorsal muscle was sampled from each fish.Proximate and amino acid compositions,as well as histology and texture of dorsal muscle were analyzed.Results showed that crude protein,crude lipid and amino acid composition of dorsal muscle were not significantly affected by treatments(P>0.05)except contents of glutamic acid(Glu),alanine(Ala),leucine(Leu)and methionine(Met)(P<0.05).Besides,the interaction of dietary carbohydrate level and protein level has significantly affected hardness of dorsal muscle(P<0.05).When dietary protein level decreased,the hardness and the gumminess of dorsal muscle decreased significantly(P<0.05),while the resilience of that increased significantly(P<0.05).Among fish from groups of the same dietary protein level,increased dietary carbohydrate significantly affected the hardness and gumminess of dorsal muscle(P<0.05).Protein level decreased,the density of muscle fiber decreased(P<0.05).In conclusion,dietary carbohydrate and protein ratio has no significant effect on nutritional composition of dorsal muscle but affects a part of amino acids and its texture indexes significantly.

Abstract:PCR and DNA sequencing technology were used to compare the DNA sequence of mitochondrial control region of 3 Channa argu populations to study the structure and the genetic diversity.The result shows that the sequence length of the D-Loop region which was used for analysis is 905-908 bp.37 polymorphic sites were found in 104 sequences and 27 haplotypes were defined.Meanwhile,the control region was analyzed,including terminal associated sequence,central conserved domains and conserved sequence block domains.The haploid type diversity(H_d),nucleotide diversity(P_i)and the average number of nucleotide differences(k)of 3 geographical populations were 0.875,0.003 27 and 2.939 respectively.Average Kimura double parameters of genetic distance between populations,genetic differentiation index(F_st),gene exchange value(N_m)and Analysis of Molecular Variance(AMOVA)all indicated that 3 populations of C.argu have high genetic differentiation.The Baiyangdian population and Pinyuan County population had certain gene exchange.

Abstract:To clarify whether the "mucus sloughing and hemorrhagic septicemia disease" of cultured European eels,Anguilla anguilla,is related with virus,the internal organs of the diseased European eel were extracted and homogenized,and virions were purified by sucrose density gradient centrifugation;then EO cells were incubated with the supernatant of the tissue homogenate,and the cytopathic effects of cell fusion appeared.In addition,the virus infected cells were thin sectioned,also the negatively stained purified virions were observed by electron microscope to photograph the virus morphology.It showed that the virus was enveloped with size in about 200 nm.Furthermore,DNA were extracted from the supernatant of the infected cells,and used for Anguillid herpesvirus(AngHV)PCR detection,and then the amplified fragment was sequenced and alignment analyzed.The results showed that it was exactly the same sequence with the AngHV European strain,AngHV-1.Therefore,the observation by electron microscope and DNA polymerase gene sequencing confirmed that the isolated virus is an AngHV strain,named AngHV-FJ,which is the first cell isolation in China mainland.The research has laid an important foundation for the study of the pathogenic mechanism of AngHV-FJ and the prevention and control of eels "mucus sloughing and hemorrhagic septicemia disease".

Abstract:In order to analyze the pathogenicity of a new strain of infectious haematopoietic necrosis virus(IHNV-Sn1203)isolated from rainbow trout farm of Shandong Province,rainbow trout fry were subjected to artificial infection test.The artificial infection test showed an accumulated average mortality rate as high as 100%(8 days),and with typical symptoms.Diseased fish samples were collected,homogenized,filtered,then inoculated onto monolayer cultures of carp epithelial cell(EPC),and further analyzed with plaque assay,electron microscopy observation,virus titer detection and homology analysis.Cytopathic effect(CPE)of the EPC cells can be observed 24 h after inoculation,most of the cells disintegrated off 72 h after inoculation.In EPC cells the virus titer was 10^8.36TCID₅₀/mL,and formed about 2 to 4 mm plaques.Rhabdovirus particles in large numbers were clearly observed in the cytoplasm by electron microscope.Phylogenetic tree was constructed based on the amino acid sequences of nucleoprotein.The results showed that the amino acid sequence of IHNV-Sn1203 nucleoprotein had 97% and 93% identity with RB-1 and WRAC,respectively,and had homology as high as 99% with the domestic zyx isolate.These results indicate that the IHNV-Sn1203 isolate can stably propagate in cells cultured in vitro with high viral titer,and can infect rainbow trout fry with high mortality.

Abstract:The molecular mechanism of sex determination in Pelodiscus sinensis has been a long-standing mystery.In many vertebrate species,SOX9 gene is required for male sexual differentiation.In this study,the mRNA and protein expression of SOX9 gene and its cellular localization in gonads of different developmental stages of both sexes were examined to investigate the involvement of SOX9 in sexual differentiation in P.sinensis.Real-time PCR results showed that,among different tissues,SOX9 gene highly expressed in testis tissue.Immunofluorescence analysis revealed that SOX9 protein started to express at embryonic stage 18,and localized in the nuclei of pre-sertoli cells in male embryonic gonads.However,no SOX9 protein was detected in female gonads during embryonic development.Moreover,SOX9 protein expression significantly decreased in estrogen-induced male to female sex reversal.Whereas SOX9 protein was triggered to highly express in aromatase inhibitor-induced female to male sex reversal.In conclusion,this study indicates that SOX9 gene is a male-specific gene and participates in the male gonadal development,which is likely to play a key role during primary male sex determination in P.sinensis.

Abstract:The experiment was conducted to determine the effects of different dietary carbohydrate(CBH)on the growth performance,body composition and serum biochemical indices of GIFT tilapia(Oreochromis niloticus).Total 720 fish(initial weight:3.03±0.3 g)were randomly assigned to 24 tanks(30 fish/tank)and fed with six experimental diets,which contained 30% different types of carbohydrate(southern brown rice,wheat middling,corn starch,potato starch,sweat potato starch and cassava starch)for 60 days.Daily feeding rate was 4%-6% wet weight.The result showed that the final body weight(FBW),the weight gain(WG),the specific growth rate(SGR)and the protein efficiency ratio in fish of southern brown rice group and corn starch group were significantly higher than those of the other 4 groups,but the feed conversion ratio was on the contrary(P<0.05).The differences in body and muscle composition were significantly affected by the types of dietary carbohydrate(P<0.05).Hepatosomatic index(HSI)is the highest in brown rice and corn starch groups(P<0.05).However,the viserosomatic index,condition factor and survival rate were not observed to have difference in all of the carbohydrate groups(P>0.05).Hepatic glycogen of corn starch group was obviously higher than that of potato starch,sweet potato starch and cassava starch groups(P<0.05),while serum glucose of fish in potato starch and sweet potato starch group is significantly lower than the cassava starch,corn starch,wheat middling,and brown rice groups(P<0.05).CHO and TG showed significant different among the carbohydrate groups(P<0.05),but other serum biochemical indices,mainly relation to TP,SOD,T-AOC and MDA examined in serum were on the contrary(P>0.05).The results indicated that GIFT tilapia could tolerate the six types of dietary containing 30% carbohydrate but they did not impair the growth performance.It was concluded that the different carbohydrate sources in diet would produce significant differences in growth performance of GIFT tilapia.Based on the growth performance(SGR),it is suggested that the optimal dietary carbohydrate sources for GIFT tilapia were brown rice and corn starch in this study.

Abstract:For silver carp(Hypophthalmichthys molitrix)surimi with four kinds of modified starch or the conventional cryoprotectant(4% sucrose+4% sorbitol),the freezing rate,thermal properties parameters during freezing phase transition and gel characteristics at -20 and -80 ℃ were measured in order to compare the cryoprotective effects of additives during freezing.The results indicated that the freezing rate of surimi at -80 ℃ was significantly higher than that at -20 ℃.The additives could significantly reduce the freezing rate and the freezing phase transition enthalpy of surimi,and improve water-holding capacity of frozen surimi gel.Higher water-holding capacity was obtained in surimi with modified starch,compared with that of surimi with the conventional cryoprotectant(P<0.05).The freezing rate of surimi with 4% sucrose(Z)+4% cross-linking esterification starch(CES)was similar to that of surimi with 4% sucrose(Z)+4% acetic acid esterified starch(AAES),and both were lower than that of the other groups at -80 ℃(P<0.05).There was no visible difference in gel strength betweeen surimi with 4% Z+4% AAES and surimi with the conventional cryoprotectant.Meanwhile,their gel strength was higher than that of the other groups at -20 and -80 ℃,respectively(P<0.05).Therefore,4% Z+4% AAES appeared to be a promising alternative cryoprotectant of the conventional cryoprotectant in frozen surimi industry,due to its notable effectiveness on the prevention of surimi quality changes during freezing.

Abstract:The purpose is to study Litopenaeus vannamei transcription factor AP-1 potential role in the immune response triggered by the virus.Our previous transcriptome results showed that the expression profile of AP-1 fluctuated significantly in response to WSSV infection.In this research,a novel AP-1 gene(GenBank Accession Number:KF999956)was cloned from Pacific white shrimp(L.vannamei).The full length cDNA of AP-1 has an 882bp ORF encoding 293 amino acids.The predicted molecular weight and calculated isoelectric point of AP-1 was 32.7 KDa and 7.80.The online software(SMART)analysis results showed that two predicted domains including the Jun protein domain and a highly conserved basic leucine zipper(bZIP)which existed in the deduced protein of AP-1.Multiple alignment analysis shows that AP-1 shared 48%,42% and 43% amino acid identities with Ixodes Scapularis,Mus musculus and Homo sapiens,respectively.Tissue expression analysis by Semi-quantitative RT-PCR revealed that expression of AP-1 gene is constitutive in all selected tissues and shows highest expression in hemocytes.The transcript of AP-1 is induced in response to white spot syndrome virus(WSSV)infection.At the early stage of WSSV infection(0.5 hpi),AP-1 did not change significantly.Then the expression of AP-1 gene began to increase after 5 hpi.At 24 hpi,the gene expression increased significantly and reached the highest level(P<0.01).From this result,it could be deduced that AP-1 gene took part in shrimp innate immune response caused by WSSV.

Abstract:A 9-week feeding trial was conducted to assess the effect of dietary starch level on growth performance,digestive enzyme activities and muscle composition of adult blunt snout bream[initial weight(161±2.7)g].Six isonitrogenous and isolipidic diets were formulated with increasing starch inclusion from 17.1 to 41.9%.At the end of the feeding trial,survival rate and specific growth rate were not affected by dietary starch level.Feed efficiency rate(FER)and protein efficiency ratio(PER)were enhanced by increasing dietary starch supplementation.Dietary starch levels did not affect total protease activities in the liver and intestine,while up-regulated amylase activities.Cellulase activities were detected in the intestine and there were no significant differences among treatments.Hepatosomatic index,liver glycogen and muscle crude lipid contents were significantly increased with the increasing dietary starch levels.Similar serum glucose,total cholesterol and triglyceride contents were observed among the treatments.However significantly lower serum complement 3 and 4 contents were observed in fish fed the highest starch diet(41.9%)compared with those fed with 17.1 or 21.8% starch diets.In conclusion,the 41.9% dietary starch level gave no negative effect on growth of adult blunt snout bream,and considering the serum complement activities,the dietary starch level should not exceed 36.3% for adult blunt snout bream.On the basis of PER and FER,the optimum dietary starch requirement of adult M.amblycephala was estimated to be 34.1% of diet and 31.4% of diet,respectively,using broken-line regression analysis.

Abstract:The studies on feeding ecology of fish are the basis for understanding the function of the whole community and ecosystem,and they will also contribute to the fisheries management.DNA barcoding is a new way to study the stomach contents,and it will also improve accuracy of the results on dietary composition by combining with morphological analysis.Hexagrammos otakii is an important commercial fish and possesses potential in aquaculture industry.Stomach contents analysis of H.otakii was investigated based on 482 individuals collected monthly from the shore reef of Lidao Rongcheng between March 2010 and February 2011.The main results were as follows:H.otakii was the demersal-feeding fish.Among the 10 prey groups,fish was the dominant prey group,and they also included polychaeta,decapoda,algae,crabs and stomatopoda,etc.The dietary composition had obvious seasonal variations:decapoda was the important prey group in every season,crabs and polychaeta in spring,fish in summer and autumn,and polychaeta were mostly in winter.The dietary composition also had obvious ontogenetic variations:<80 mm SL preyed on decapoda and amphipoda;80-119 mm SL preyed on polychaeta,stomatopoda larvae and decapoda;>119 mm SL preyed on fish,decapoda and crabs.The feeding intensity had obvious seasonal variations,with highest in summer and lowest in winter.The feeding intensity also had obvious ontogenetic variations,reached the highest feeding intensity in <80 mm SL,then decreased with increasing standard length,and gradually increased after >180 mm SL.Six samples could be identified based on DNA barcoding,among which,four samples were identified as species,other two samples were identified as genus and family respectively.