Abstract:This study cloned the complete mitochondrial genome sequences of Megalobrama skolkovii,M.pellegrini and M.terminalis based on the complete mitochondrial genome sequences of M. amblycephala and partial mitochondrial genome sequences of M.hoffmanni,M.ellegrini and M.terminalis in the GenBank database.The complete mitochondrial genome sequences of four species in the genus Megalobrama were analyzed.Results showed that all the mitochondrial genomes of the four Megalobrama fishes contained 13 protein-coding genes,22 tRNA genes,2 rRNA genes,a non-coding control region(D-loop)and a replication origin region of the light chain(OL),with identical arrangement and tightly packed.Eight tRNAs and ND6 genes were encoded on the light strand(L strand),and the remainders encoded on the heavy strand(H strand).All 13 protein-coding genes of the mitochondrial genomes from four species of the genus Megalobrama showed a strong bias toward A+T and a bias for C nucleotides.The comparison of the complete mitochondrial genome sequences showed that there were 758 variable sites,including 691 singleton variable sites(accounting for 91.19%),67 parsimony informative sites(only accounting for 8.84%).Eleven of 22 tRNA genes had mutated in Megalobrama,and 23 variable sites were mainly distributed in the TΨC and DHU of the cloverleaf secondary structure.Additionally,626 variable sites of the protein-coding genes were mainly distributed in the third codon position(accounting for 82.59%)and Cyt b gene had the largest number of different loci(84),followed by ND4 gene with 83 loci.Therefore,Cyt b and ND4 could be used as alternative molecular markers for genetics research in the genus Megalobrama groups,which provided a theoretical and technical basis for the rational and efficient use of biological resources and conservation of biological diversity.Both ML and BI phylogenetic trees based on the complete mitochondrial genome sequences from four species showed that M.terminalis and M.pellegrini had the closest genetic relationship,with M.amblycephala being more closely related to them,and M.hoffmanni was farther related to the other species.

Abstract:In the study,18 pairs of primers which could give stable and polymorphic amplification profiles were screened out from 60 microsatellite loci and used to analyze the genetic structure of Parabramis and Megalobrama species.Meanwhile,the microsatellite DNA fingerprinting in six populations of genera Parabramis and Megalobrama was established based on the results of alleles of microsatellite loci by Popgen1.32 software package and illustrative patterns were constructed by EXCEL office software,including two geographic populations of M.terminalis from Dong River(SJF1)and Qiantang River(SJF2),M.hoffmanni(GDF),M.pellegrini(HHF),M.amblycephala(TTF)and P.pekinensis(CCB).The results showed that a total of 221 alleles were obtained from the six genera Parabramis and Megalobrama populations,and the alleles ranged from 2-20 in each locus.The mean value of number on alleles(N_a)of SJF1,SJF2,HHF,GDF,TTF and CCB was 5.17,6.11,3.5,6.56,5.22 and 5.22,the mean value of expected heterozygosity(H_e)was 0.634 2,0.720 4,0.546 2,0.681 0,0.675 2 and 0.559 7,and the average value of polymorphism information content(PIC)was 0.575 6,0.666 9,0.472 0,0.630 6,0.606 4 and 0.517 0,respectively.It demonstrated that the genetic diversity of SJF2 was the highest and HHF was the lowest among the six populations.Using unweighted pair-group method with arithmetic means method(UPGMA)based on their genetic distances,the cluster analysis in six populations showed that SJF2 and TTF first grouped together,genetic distance was 0.560 6;then they clustered with SJF1,GDF,HHF,CCB in sequence;the genetic distance between HHF and CCB was 1.759 2,which was the farthest.In addition,nine pairs of specific microsatellite markers(TTF1,TTF2,TTF3,TTF7,TTF10,Mam03,Mam25,EST37 and EST66)were screened from microsatellite DNA fingerprinting which could be used to identify most of genera Parabramis and Megalobrama populations.Particularly,microsatellite primers(Mam03 or EST37)could differentiate P.pekinensis(CCB)from genus Megalobrama populations and microsatellite markers(TTF3,EST37,TTF2/TTF10,EST66)combination could completely identify SJF1,HHF and GDF populations among Megalobrama spp..However,as a result of the relative consistency of the genetic characteristics,specific SSR markers,which could distinguish M.terminalis from Qiantang River(SJF2)and M.amblycephala(TTF),were not found.Overall,these results could provide a theoretical basis for germplasm conservation,species identification and genetic breeding of genera Parabramis and Megalobrama in China.

Abstract:Lesser-spotted leatherjacket Thamnaconus hypargyreus is an economically important fish species in the South China Sea.It is necessary to study its genetic structure for the exploitation and management of the fishery resources.Fish specimens(totally 156 individuals)used in this study were collected from 5 sampling locations in the north of the South China Sea and the southwest of Nansha.The results were as follows:the mitochondrial cytochrome b(Cyt b)gene sequences of the fish was amplified by polymerase chain reaction(PCR)technology.Both 56 mutations of nucleotide acids without inserting or deleting one and 58 haplotypes were found among the examined 779 base-pair nucleotide sequences of Cyt b fragment.The ranges and the level of average genetic distance were 0.002 95-0.004 15 for T.hypargyreus between groups.All 5 groups were characterized with high haplotype diversity(0.820 1-0.980 4)and relatively low nucleotide diversity(0.002 62-0.004 69).Analysis of molecular variance(AMOVA)and the fixation indices(F_st)of 5 groups showed that the genetic variance mainly came from individuals within groups,and there was no genetic differentiation between groups.With high gene flow,this group could be developed and managed as an evolutional significant unit.The median-joining(MJ)network and phylogenetic tree proved no phylogeographic differentiation structure in 5 groups.According to the criteria distinguishing different populations,species and genera given by scholar Kartavtsev,the five groups should be merged to the same population,which implied T.hypargyreus in the North and South-West Continental Shelf of the South China Sea belongs to one population.The findings would provide a scientific basis for the study of migration of T.hypargyreus between the two Continental Shelves and management of its stock.

Abstract:The genetic diversity and population genetic structure of Paraoncidium reevesii were investigated using mitochondrial cytochrome c oxidase subunit I(COⅠ)gene sequences.A total of 171 individuals representing 8 collection sites were included in the analysis.Overall,101 haplotypes were dened and 117 polymorphic sites were observed.The P.reevesii populations had high haplotype diversity(0.974±0.005)and nucleotide diversity(0.032 2±0.001 3).The AMOVA test of P.reevesii populations based on haplotype frequencies revealed that 49.01% of the genetic variation occurred within the populations,whereas 50.99% of the genetic variation occurred among populations.Pairwise xation index(F_st),gene flow(N_m)and IBD analysis indicated signicant genetic structure have appeared in P.reevesii populations.Demographic analyses indicated populations ZJ,CN,HN,WC and TH might have experienced population expansion,and the time of expansion of Chinese populations could be 0.781-0.725 Ma BP,whereas the time of expansion of population TH could be 0.035 Ma BP.The phenomenon might occur in Pleistocene period with melting of glaciers,changes of climate warming and rising of sea level.

Abstract:Plecoglossus altivelis is an important rare economic fish distributed along Chinese,Japanese and Korean coasts.In the present study,genetic diversity of hatchery and wild population was compared.A 445 bp fragment of control region was obtained.The haplotype diversity(0.198 4±0.092 4)and nucleotide diversity(0.000 8±0.000 9)of hatchery population were obviously lower than those of wild population(h=0.810 5±0.067; π=0.002 6±0.002 0).Great differentiation was detected between these two populations(F_st=0.447,P=0.000).The topology constructed by neighbour-joining tree indicated no significant genealogical structures for two populations.Individuals from Japan showed a distant relationship with individuals from China.Mismatch distribution analysis indicated that P.altivelis may have experienced a recent population expansion.The present study indicated that current genetic situation of hatchery and wild populations was not optimistic.

Abstract:In East-Asian countries,the ark shell Scapharca broughtonii is one of the most commercially important shellfish resources.In China,however,the wild resources of S.broughtonii have experienced a dramatic decline in abundance for the past decades due to overfishing,declining water quality,and loss of habitat.To develop management strategies and optimize the hatchery-based seed production,the reproductive cycle and seasonal variations in biochemical composition of S.broughtonii from the coast of Shandong Peninsula were investigated from October 2010 to September 2011 in relation to environmental factors.The specimens were collected monthly,with temperature and chlorophyll a concentration in seawater column recorded synchronically.Standard histological techniques were used to analyse the gonadal development,and the seasonal cycles of the biochemical composition of separate organs of mantle,adductor muscle,gonad-visceral mass and foot were examined.Histological analysis showed a unimodal gametogenesis cycle with one spawning season(June-August)during the year.The gonads of both sexes showed synchronical development,enhancing the probability of fertilization.The gametogenesis of the ark shell initiated simultaneously with temperature and chlorophyll a concentration ascending.Mean oocyte diameter increased gradually during ovarian maturation,reaching the maximum(41.80 μm)ahead of spawning.The sex ratio of female to male was approximately 1:1,indicating that there was no difference in the quantities of both sexes inhabiting this area.Although the lipid content in the gonad was relatively low compared with those of protein and carbohydrate,it displayed a seasonal pattern coincident with the gonadal development of the ark shell,showing an evidence that it is a major component of bivalve oocytes.A significant increase in the glycogen content of all tissues during the gametogenesis suggested carbohydrates play the most important role in this species.Except for the adductor muscle,two significant decreases in the protein content were observed during the spawning peak and winter,which implied protein not only supports reproduction,but also meets the energy demand after glycogen was depleted.

Abstract:Relative abundance index is often used to measure the level of fisheries resources biomass.Based on chub mackerel(Scomber japonicus)catch data of the large lighting-purse seine fishery from 1999 to 2011,the impacts of temporal(Year,Month),spatial(Longitude,Latitude),environmental factors(Sea surface temperature,Sea surface height and Sea surface chlorophyll-a concentration)and fishing performance(Vessel name)on catch per unit effort(CPUE)were analyzed using generalized linear model(GLM)and generalized additive model(GAM).The Year effect of CPUE,extracted from GAM,was used as the annual abundance index(AI)to reflect the inter-annual variation of chub mackerel abundance in the East China Sea and Yellow Sea.The relationship between AI and SST in the chub mackerel spawning ground and fishing effort was also investigated.The GAM with the eight variables explains 11.69% of the total variance in nominal CPUE,and the impact of Year on CPUE is the foremost factor,contributing to 53.9% of the total reduction in deviance.The extracted Year effect indicates that chub mackerel abundance shows a declining trend over the past 13 years,especially after 2008,and the AI fell from 1.22 in 2008 to 0.82 in 2011.The AI shows a significantly positive relationship with the SST of the spawning ground,and it is expressed as AI=-3.5+023SST(P<0.05).This result indicates that SST of the spawning ground has a positive impact on the abundance of chub mackerel.The decrease of chub mackerel abundance in the East China Sea and Yellow Sea resulted from the rapidly increasing number of purse seine vessels in the recent years.

Abstract:Sousa chinensis(Osbeck,1765)is a species of Sousa genus,which is found in the South China Sea,the East China Sea and the Yellow Sea.Some scientists have done much systematic study on skull and body external morphology.To deeply study the skeleton of Sousa chinensis, in this paper,a Sousa chinensis sample from Guangdong Pearl River Estuary Chinese White Dolphin National Nature Reserve was anatomized,and a set of skeleton sample was obtained,which was measured overall.The order is anatomy-taking bone-cooked-skim with alcohol-skim with gasoline-string together.The results showed that the maximum height,the maximum width and the maximum thickness scales of V type skeleton of Sousa chinensis became larger gradually first,then became smaller gradually,and the significantly quadratic function(R²=0.864 1)was found between the weight and length of lumbar spine.The significantly power functions(R²=0.964 6,R²=0.912 8)were found between the weight and height and between the weight and length of caudal vertebra.The significantly exponential function(R²=0.970 9)was found between the weight and width of caudal vertebra.The quadratic function could be well used to fit the correlation between the weight and maximum height of the V type bone(R²=0.754 6).The left rib and right rib were symmetrical.

Abstract:This paper studied the albinism of half-smooth tongue sole by establishing families,and 17 half-smooth tongue sole families were established.Firstly,sampling statistics and variance analysis have been conducted for the albinism rate,including statistics for the eyes abnormal rate of albinistic individuals in given families.Secondly,the growth of albinos and normal individuals in 4 higher albinism rate families was compared.Finally,the resistance to Vibrio anguillarum was tested in the 4 given families for the albinistic and normal individuals respectively.The results are as follows:the albinism rates in different Families were quite different,the albinism rate in Family 3 is the highest which was 94.50%,and that in Families 15,33 and 37 was 0.00%;while the families whose sire is cultured population have the highest average albinism rate,which is 19.68%,while the families whose sire is wild population have the lowest albinism rate,which is 3.21%.The average albinism rate of the families whose sire is selected population is 7.50%,however,there is no significant difference among them(P>0.05).There are 3 families that the albinism rate was higher,the albinism rate of Family 5 is 48.48%,that of Family 10 is 45.83%,and that of Family 12 is 88.89%.4 families were selected for comparison of their albinos and normal individuals growth,and we found that the growth of albinistic individuals whose age was 3 to 4 months was slower or significantly slower than normal individuals in total length and body width and body weight in the same family,whereas,when they were 12 to 13 months old,this kind of difference was not significant any more,and albinos in Family 1 and Family 17 even exceeded normal individuals in total length and body width and body weight.Albinistic and normal individuals in 4 given families were injected with V.anguillarum,and we found that the mortality rate of albinistic individuals was lower than that of the normal individuals in the same family respectively,the disease-resistance of the albinos in Family 1 and Family 17 was greatly higher than that of normal individuals,and the declines were 24.92% and 20.25% separately.This study indicates that progenies of half-smooth tongue sole whose parents are from wild population tend to have a lower albinism rate,and the albinism could associate with a certain proportion of abnormality of eyes.We also found that at the early growth stage,albinistic larvae grew slower and later they grew faster,even faster than the normal individuals.Moreover,the disease-resistance of albinos is superior to the normal individuals in the same family.

Abstract:For the reason that the critical thermal maximum(CTMax)is an excellent index for evaluating the thermal tolerance,we assessed the impact of different acclimation temperatures(24,28,32 ℃)and heating rates[(1±0.2)℃/h and (1±0.2)℃/min] on the CTMax values firstly.And then we compared the difference of the thermotolerance between the two morphologically similar varieties of juvenile kuruma shrimp Marsupenaeus japonicus(Bate,1888)by the CTMax values and the acclimation response ratio(ARR)values,and at the same time,the different distribution,the physiological traits of the oxygen consumption rate,suffocation point and temperature coefcient(Q₁₀)of the two varieties were analysed to explore their thermal tolerance mechanism.The results are as follows:(1)Significant effect was found on the CTMax values of the shrimps by different heating rates and acclimation temperatures(P<0.05).(2)At the acclimation temperature of 32 ℃,the CTMax value of variety Ⅱ was greater than that of variety Ⅰ(P<0.05)and the ARR values of variety Ⅱ were also greater than variety Ⅰ at all temperature intervals.(3)When exposed to the same acclimation temperature,the oxygen consumption rate and suffocation point of the variety Ⅰ were greater than those of variety Ⅱ(P<0.05).(4)The temperature coefcient(Q₁₀)value of variety Ⅰ at the temperature interval of 28-32 ℃ was greater than that of 24-28 ℃,while the result of variety Ⅱ was quite the contrary,and there was a difference between the optimum temperature of the two varieties.The results obtained in this work showed that the CTMax values,oxygen consumption rate and suffocation point of the juvenile kuruma shrimp were influenced by different acclimation temperatures and the thermotolerance of variety Ⅱ which is mainly distributed in the South China Sea was stronger than that of variety Ⅰ which is distributed in the East China Sea and the northern part of the South China Sea.

Abstract:This study evaluated the effects of fish meal replacement with soy protein concentrate(SPC)on feed intake,growth and nutrient utilization of turbot,Scophthalmus maximus.Five experimental diets were formulated,in which FM protein was replaced by SPC at 0,12%,25%,37%(S75)and 49.5%,respectively.Five diets were supplemented with 0,0.83%,1.65%,2.48% and 3.30% essential amino acid mixture(L-lysine:DL-methionine:L-leucine:L-valine:L-threonine=18:6:3:2.5:2).Each diet was randomly assigned to triplicate groups of fish,and each group was stocked with 16 turbot [with an initial weight of (31.1±0.1)g] in 15 fiberglass tanks(300 L).Fish were fed twice daily(8:30 and 17:00)to visual satiation for 9 weeks.At the end of the growth experiment,feed intake(FI)(P<0.001)and specific growth rate(SGR)(P<0.001)decreased linearly with increasing dietary SPC levels.There were no significant differences(P>0.05)in feed efficiency ratio(FER)and protein efficiency ratio(PER)among fish fed diets with 0-37%SPC.Apparent digestibility coefficients of dry matter and crude protein of the diets were not significantly(P>0.05)affected by dietary treatments.These results indicate that protein from SPC could not effectively replace FM protein in diets of turbot because of lower feed intake.

Abstract:Lipid and fatty acids are among the most vital factors that provide marine fish with structural components and energy resources.The fatty acid reserves of broodstocks profoundly affect the fecundity of spawners as well as the quality of the newly hatched larvae.In order to state the characteristics of lipid and fatty acid accumulation in wild-caught broodstocks of Pampus argenteus,the lipid and fatty acid content in different tissues of wild broodstocks of silver pomfret,Pampus argenteus from Mindong Seazone during the reproductive season were quantitatively investigated with the methods of chloroform-methanol and gas chromatography.The results indicated that there were significant differences in lipid content among gonad,liver and muscle.Mean total lipid levels(% in dry weight)in ovary,testis,liver and muscle were 35.76%,15.11%,22.07% and 22.14%,respectively.Testis displayed the highest proportion of polar lipid/total lipid,while muscle displayed the lowest proportion of polar lipid/total lipid.During the reproductive season,the total lipids and neutral lipid contents in ovary increased significantly with the development of the ovary,while the polar lipid content in muscle decreased significantly with the development of the testis.The contents of 20:5n-3(EPA,2.25-3.87 mg/g),22:6n-3(DHA,6.71-13.03 mg/g)and highly unsaturated fatty acids(HUFAs,17.20-29.64 mg/g)in neutral lipid of ovary were the highest.The contents of EPA(0.38-0.27 mg/g)and DHA(3.12-3.59 mg/g)in polar lipid of testis were the highest.The n-3/n-6 ratio in gonad was significantly higher than those in liver and muscle.The essential fatty acids such as DHA were transferred among the tissues and between different lipid classes of the same tissue.It is therefore suggested that significant differences in total lipid content,total lipid classes and fatty acid contents(mg/g dry mass)were displayed not only among the tissues,but also between different lipid classes of the same tissue.The essential fatty acids were preferentially transferred from neutral lipid in muscle and liver to neutral lipid in ovary with the maturation of ovary.

Abstract:Photoperiod regimes(hours of light:hours of dark)were designed as 1L:23D,9L:15D,12L:12D,15L:9D,and 24L:0D to investigate the effects of photoperiods on the growth and biochemical parameters of juvenile brown flounder(Paralichthys olivaceus).At the end of the experiment,the average weight of the fish varied from 41.10 g to 43.98 g and no significant difference appeared in the average body weight through the experimental period.The average body weight did not show significant correlation to the photoperiods.The average DGC of the whole experimental period varied from 1.86 to 2.02 and no significant difference existed.Significant difference of daily growth coefficient(DGC)appeared only in period 21-30 d.A slightly decending trend of DGC along with the extending of light period was observed.The feeding rate of 12L:12D was significantly higher than 9L:15D in period 31-40 d.or the whole experimental period,and feeding rate of 1L:23D(1.64)was significantly lower than that of 12L:12D(1.79).The feed conversion efficiency showed a decending trends along with the extending of light period.Feed conversion efficiency of 1L:23D(113.49)was significantly higher than those of 12L:12D,15L:9D,and 24L:0D and it was also slightly higher than that of 9L:15D.Difference of the proportion allocation of ingested energy through whole experimental periods appeared only in excretion energy.The highest and lowest excretion energy appeared in 15L:9D and 12L:12D respectively.Photoperiods showed significant effects on the 24 h oxygen consumption rate of fish and the highest and lowest oxygen consumption rates appeared in 15L:9D and 24L:0D respectively.The oxygen consumption rate ascended along with the light period extending from 1 h to 15 h and then descended along with the light period extending from 15 h to 24 h.The content of growth hormone and insulin-like growth factor I in plasma showed no significant difference among different treatments and showed no obviously fluctuating trend along with the extending of light period. The content of melatonin in plasma ascended along with the light period extending from 1 h to 12 h and then descended along with the light period extending from 12 h to 24 h.The content of melatonin of 12L:12D was the lowest.But it was not significantly different from other treatments.The RNA/DNA ratio in muscle ascended along with the light period extending and the RNA/DNA ratios in 15L:9D and 24L:0D were significantly higher than that in 1L:23D.The highest and lowest RNA/DNA ratios in liver appeared in 12L:12D and 15L:9D respectively.The results of the experiment indicated that photoperiod has significant effects on the feeding rate and feed conversion efficiency of the whole experimental period.But the feed conversion efficiency of the feeding declined treatment was increased because the oxygen consumption rate was decreased.Thus the photoperiods did not have significant effects on the growth of fish.Photoperiods have significant effects on the content of melatonin in plasma,and RNA/DNA ratio in muscle and liver,but the differences of these parameters show no significant correlation to the growth of fish.

Abstract:This experiment was conducted to study the effects of dietary L-malic acid levels on intestinal histology and function,and TCA cycle efficiency in liver of Gift tilapia.The experimental diets supplemented with 0(control group),1.0,2.0,4.0,8.0,16.0 and 32.0 g/kg L-malic acid had been fed to juvenile tilapia with initial body weight of(37.94±0.09)g for 154 days.420 juvenile tilapia were randomly divided into seven groups and each group had three replicates(20 fishes for each replicate).The results showed that:With the increment of L-malic acid supplement,the villus height,villus density and muscular thickness of foregut and midgut reached the highest in 16.0 g/kg group which was significantly higher than those in control group(P<0.05),and the villus height,villus density and muscular thickness of hindgut gradually decreased(P<0.05).Intestinal amylase and lipase activities reached the highest in 1.0 g/kg group which were significantly higher than those in control group(P<0.05).The protease activity,and the content of ATP increased gradually with the increased level of L-malic acid(P<0.05).The activity of Na⁺-K⁺-ATPase,and the intestinal content of EGF and EGFR reached the highest in 16.0 g/kg group,meanwhile citrate synthase activity reached the highest in 8.0 g/kg group.This study indicates that in the dietary of Gift tilapia,a proper addition of L-malic acid(1.0-8.0 g/kg)can improve the morphology of foregut and midgut,promote the proliferation of intestinal mucosal epithelial cell,and improve the ability of intestinal digestion and absorption and the efficiency of liver TCA cycle.

Abstract:The pearl oyster,Pinctada fucata,is the most important species cultured widely for production of marine pearls in the coastal provinces of South China,while mass mortalities of the cultured pearl oyster have occurred frequently in juvenile,mother and operated oysters.Understanding the immune defense mechanisms of the pearl oyster may contribute to the development of novel management strategies for diseases control and the long-term sustainability of pearl industry.In this study,a suppression subtractive hybridization(SSH)cDNA library was constructed from the hemocytes of P.fucata challenged with Vibrio alginolyticus,and β-actin gene was used as internal control to estimate the efficiency of subtractive cDNA.A total of 600 clones in the SSH library were randomly selected and sequenced.The results showed that β-actin was subtracted significantly at about 2¹⁰ folds,suggested that the subtractive cDNA library was successfully constructed.PCR analysis showed that the inserts were 100-750 bp in length.Based on BLAST searches in NCBI,167 ESTs(40.34%)exhibited homology with genes of known functions,and 7 of the 167 ESTs(1.69%)were possibly related to immune and stress functions,and the remaining 204 ESTs had no significant matches with known sequences in the GenBank database.Altogether,the results obtained from this paper provide valuable information for further investigating the molecular immune mechanism of P.fucata.

Abstract:The purpose of this study is to establish a TaqMan real-time fluorescence quantitative PCR method which can be used to detect hybrid snakehead rhabdovirus(HSHRV).A coding region of HSHRV-C1207 strain G protein was amplified by PCR and cloned into pMD18-T vector for the construction of recombinant plasmid.After being identified and confirmed by sequencing,the recombinant plasmids were extracted and 10-fold serial dilutions of recombinant plasmid were used as standard plasmid.A pair of specific primers and TaqMan probes were designed targeting the C1207 strain G gene.The standard plasmid was used as a quantitative template to establish the TaqMan real-time fluorescence quantitative PCR method for HSHRV detection and the sensitivity,repeatability and specificity of the method were evaluated.The results showed that the TaqMan real-time fluorescence quantitative PCR method was established and the correlation coefficient(R²)and the slope of the standard curve were 0.999 and -3.290 respectively,which showed a good linear relationship.Sensitivity tests showed that the detection limit was 10 copies,which indicated that the sensitivity of the real time PCR is about 100 times higher than that of the conventional PCR assay.Results of repeatability tests showed that the coefficient of variation was 0.84%,indicating that this method had high repeatability.Furthermore,the method had high specificity for HSHRV without cross reactions with templates from other aquatic viruses.In clinical samples tests,detection rate of established fluorescence PCR was higher than that of conventional PCR.The TaqMan real-time fluorescence quantitative PCR established in this study has high sensitivity,repeatability and specificity for the rapid detection and quantification of HSHRV in fish.

Abstract:In the current research,acid soluble collagen(ASC)from skipjack tuna(Katsuwonus pelamis)fishbone was successfully isolated with the yield of 2.47%(dry weight basis).The antioxidant hydrolysate of ASC(TFCH)was prepared through a two-stage in vitro digestion(3-h pepsin followed by 3-h trypsin),and one new antioxidant peptide(TFCH-P2)was further isolated from TFCH using ultrafiltration,gel chromatography,and RP-HPLC.The amino acid sequence of TFCH-P2 was identified as Gly-Pro-Ala-Gly-Pro-Ala-Gly-Glu-Gln-Gly(GPAGPAGQEG)with molecular weight of 839.87 u([M+H]⁺ 840.68 u).TFCH-P2 exhibited good scavenging activity on DPPH radical,hydroxyl radical,ABTS radical and superoxide anion radical with EC₅₀ of 0.18,0.97,0.52 and 0.38 mg/mL,respectively.TFCH-P2 was also effectively against lipid peroxidation in a linoleic acid model system.The antioxidant activity of TFCH-P2 was due to the presence of hydrophobic amino acid residues within the peptide sequence.The result suggested that TFCH-P2 could be used as natural antioxidant in enhancing antioxidant properties of functional foods and in preventing oxidation reactions in food processing.

Abstract:A large number of marine pelagic fishes inhabit China's seawaters.In the past few years,their total capture production accounted for 40% of total marine catches in the country.Marine pelagic fishes of Scomber japonicas,Decapterus maruadsi and Engraulis japonicas belong to r-selection of life history pattern,and their resources usually recover faster than those of the demersal or near demersal fish species.Therefore,the resources of marine pelagic fishes can be used more sustainably.Development of important marine pelagic fisheries in China is reviewed in this paper,particularly with regard to the five top production species,i.e.Scomber japonicus, Decapterus maruadsi,Scomberomorus niphonius, Pampus punctatissimus and Engraulis japonicus.Research status of resource biology of population identification and classification,migration and distribution,wintering ground,spawning ground and period,age and growth,feeding habits,fecundity and stock structure of the five species,together with the assessment of their biomass and total allowable catches is illustrated.Future study on their resource biology is also discussed.