Abstract:The Vasa gene encodes a protein of DEAD-box family that is essential for PGCs proliferation.In this study,we characterized the cDNA of Vasa and researched its expression in the reproductive cycle of Cynoglossus semilaevis through RACE and RT-PCR technology,aiming to clarify its function in gametogenesis of fishes.The length ef Vasa gene is 2 602 bp and this gene encodes a protein of 722 amino acids.The dudced amino acid sequence contains 8 conserved motifs of DEAD-box family protein,5 RGG repeats and 10 RG repeats in N-terminal region.Comparisons of the deduced amino acid sequence with those of other vertebrates and invertebrates revealed the highest homology(91%)with Thunnus orientalis. Vasa was strongly expressed in gonad and little expressed in heart.In the reproductive cycle,the transcript level of Vasa gene in the primary yolk stage and tertiary yolk stage is higher than peri-nucleolus stage and atretic follicles in ovary.The transcript level of spermatogenesis stage is obviously higher than that of spermatocyte stage and spermiation stage.These results suggest that Vasa gene may play an important role in spermatogenesis and oogenesis during reproductive cycle.

Abstract:The family Sciaenidae,commonly known as drums or croakers,are distributed in the Atlantic,Indian and Pacific Oceans.This family comprises of fresh,brackish and marine species and about 270 species in 70 genera.The classification and evolutionary relationships of Sciaenidae have always been hindered by the overwhelming mumber of species,wild distribution and lack of morphological specializations traditionally used in ichthyological classification.The confusion and debates have brought much trouble to the study of the phylogenetic relationships among Sciaenidae.In this study,to evaluate the phylogenetic relationship of Sciaenidae in the China Sea,the RAG1 genes sequences of 13 species within 9 genera were amplified and sequenced.After alignment,about 1 498 bp length fragments which could be used for sequence analysis were obtained.The genetic information indexes were generated using MEGA3.1 software and phylogenetic trees were reconstructed by Treefinder software.Of the 1 498 bp aligned base pairs,230 sites were variable,accounting for 15.4% of the total base pairs.Molecular phylogenetic tree was constructed based on the maximaum-likelihood(ML),neighbor-joining(NJ)and maximum-parsimony(MP)methods,with Anabas testudineus as the designated outgroup.Conclusions were drawn as follows:(1) The tree indicated the 13 Sciaenidae species in China were grouped in two clusters.(2) Johninae and Sciaeninae were clustered together in the basal position,suggesting they are most primitive groups among the family Sciaenidae,which supported the previous conclusions based on morphology.(3) The phylogenetic trees showed that Nibea derived from Sciaenidae earlier than Pennahia. However,the morphologic view regarding these two genera as the same subfamily was not well supported yet and further analysis using multiple genes with different evolutional rates was recommended.(4) O.argenteus and C.aureus might be grouped in two different genera of one subfamily.(5) Larimichthyinae was the latest derived clade,which supported the previous conclusions based on morphology.Due to the lack of high bootstrap values support,the species-level within this clade was not highly consistent with that based on morphology.

Abstract:Trionyx sinensis is regarded as a very important fishery animals with high economic value.However,the germplasm resources of Trionyx sinensis are exposed to admixture and degeneration due to the booming industry. The investigation of genetic diversity of Trionyx sinensis is beneficial to protect the germplasm resources.In the present study,the variation and genetic diversity of mtDNA D-loop region partial sequences in three geographical populations of Trionyx sinensis were analyzed by PCR combined with DNA sequencing and SSCP techniques.The average contents of A T(65.4%)were higher than that of G C (34.6%).A total of 7 variable sites(about 5.7% of the total nucleotides in the sequence)were detected in 25 individuals,and the value of si/sv was 2.76.The nucleotide diversity(π)of the 25 individuals was 0.019 95, and the average number of nucleotide differences(K) of them was 2.453.The 25 individuals belonged to 6 haplotypes according to the determined sequences.The haplotype diversity (H_d)was 0.707,and the average genetic distance(P) among the haplotypes of the species was 0.027.The analysis of phylogenetic tree with the method of UPGMA showed that the 6 haplotypes were clustered into three groups.Our data indicated that the variation and genetic diversity were high in the three populations of T.sinensis, in which the genetic diversity of Japanese population was richer than that of Huanghe and Huangsha population,and the genetic distance between Huangsha population and the other two populations was far.Moreover,we found that two types of electrophoretic patterns could be detected by PCR-SSCP,and all type Ⅱwere Japanese population,suggesting the effective application of PCR-SSCP method in 78 TT-AA transversion mutation sites testing.

Abstract:The genetic structure of different trituberculatus generations was analyzed based on microsatellite DNA markers. Sixteen microsatellite markers were used to analyze the genetic structure and genetic diversity of the selected populations of inbred Portunus rituberculatus from F1 to F4. The results showed that the genetic diversity of the breeding population was decreasing . The the average polymorphism information content (PIC) of the 16 microsatellite markers decreased from 0. 6753 to 0.4061, the average allele number from 3.5 to 2.1333, the average heterozygosity from 0.6435 to 0.4774 and the average rate of allele homozygous from 0.5669 to 0.4024. We tested all loci for H-W, there are different degrees of deviation from equilibrium in each generation. There are different degrees of genetic differentiation by F-test for each system, the results show that 19.07% of the genetic differentiation is among populations, 80.93% of the genetic differentiation is within the group. In addition, the Fis value calculations show that four families on the whole are expressed as a certain degree of heterozygosity, which F4 has 12 sites, F3 has six sites, F2 has three sites, F1, 8 loci in heterozygosity status.Increasing genetic distance, adjacent genetic similarity between generations gradually increased. With the breeding, the results show that after 4 consecutive generations of breeding.The genetic basis of breeding gradually purified homozygous and genotype gradually moving towards stable.We are expected to get more stable strains with further breeding.

Abstract:The Vasa gene encoding an ATP-dependent RNA helicase protein member of the DEAD-box family, is one of the important regulatory factors which determines the germline cells development.In the present study,homolog cloning strategy and SMART RACE technique were used to isolate and clone the Vasa gene of U.unicinctus, a sole commercial species of Xenopenusta.The full length of the Vasa cDNA sequence is 4 080 bp,comprising an open reading frame(ORF)of 2 322 bp encoding a polypeptide of 773 amino acids,sharing nine conserved motifs of all DEAD-box family proteins.Phylogenetic analysis showed the deduced amino acids sequence contributes to the VASA relate proteins.The temporal expression analysis of Vasa mRNA using RT-PCR and in situ hybridization techniques indicated Vasa mRNA was present in unfertilized eggs,fertilized eggs and 2-8 cell embryos,suggesting a maternally-provided characteristic.The expression level decreased obviously at blastula stage,and kept the low level from blastulas to worm-like larvae and juveniles. In situ hybridizations howed that Uu-Vasa mRNA is distributed equally in the cytoplasm of early embryos from unfertilized egg,fertilized egg to blastula. At gastrula stage, Uu-Vasa mRNA concentrated on endoderm and mesoderm of gastrula.In rtochophore, the Vasa positive signals are located in cells of alimentary canal.During the somite larvae,the hybridization signals appear in the cells of body segment membrane and alimentary canal.When developing to worm-like larvae, Un-Vasa is detected in abdominal bristle of the head region and posterior region of intestine.The location of positive signals in the posterior region of intestine is coincident with that of gonad in the future,and it was deduced that U.unicinctus gonad maybe initializes to form in worm-like larva.Our results provide primary data to generate new insight into the origin and differentiation of germ cells as well as the gonad genesis and differentiation in U.unicinctus.

Abstract:As a variety of cytokines receptors,epidermal growth factor receptor(EGFR)plays an important role in cell proliferation,migration and differentiation.It was not only involved in regulating growth and development in tissues,but also in the wound healing.In the present study,cDNA full-length sequence of the EGFR gene was cloned in coelomocytes of Apostichopus japonicus, by using 3′ RACE and 5′ RACE,and the sequence and structural analysis of the EGFR gene by using bioinformatics methods.The results showed that the cDNA length was 3 826 bp,including the 821 bp of the 5′-UTR and 281 bp of the 3′-UTR.The open reading frame was 2 724 bp,which could encode 907 amino acids.The deduced amino acid sequence of 55-184aa and 365-487aa was L1 and L2 receptor domain of the EGFR gene.The CR1 and CR2 cysteine-rich regions,which were transmembrane glycoprotein,were located in the 203-344aa and 503-823aa regions.Identity rates of deduced amino acid sequence of EGFR with those of known species were subjected to BlastP searching in NCBI.Results showed that the structure of EGFR gene in the study was similar to that of other species EGFR gene,and the amino acid sequence of EGFR gene of A.japonicus was 49% in similarity and 34% in homology with EGFR of Drosophila melanogaster and 47% in similarity and 34% in homology with EGFR of Danio rerio and 49% in similarity and 31% in homology with EGFR of Lymnaea stagnalis. All results indicate that the EGFR gene of A.japonicus detected in this study is one of the EGFR family members.Based on the results above,expression of EGFR in different tissues by relative quantitative RT-PCR, the internal standard gene was Cytb. The result showed EGFR expresses in every tissue of A. japonicus, especially higher in coelomocyte and epidermis,which was 143.87 and 51.67 times of the respiratory tree,and the difference was significant to other tissues (P<0.05).The expression of intestine and longitudinal muscle was low,only 10.82 times and 4.47 times of respiratory tree,and the difference was not significant (P>0.05).These results indicate that the EGFR plays an important role in cell growth and tissue regeneration of A. japonicus.

Abstract:Saccharina japonica (Aresch.)C.E.Lane,C.Mayes et G.W.Saunders(=Laminaria japonica Aresch.)(Phaeophyta)is an important economic seaweed in China.There is a distinct outcome about the chromosome number in this kelp due to the tiny size of these chromosomes.The karyotypes and chromosomes of S.japonica were observed after a series of treatments including pretreatment with 0.2% colchicines for about 10 h,Carnoy’s fixative,and mixture of enzymes prior to dropping from 30 cm height overhead glass slides for spreading the surface coat.The prepared chromosomes were stained with 4′,6-diamidino-2-phenylindole(DAPI), a fluorescent probe sensitive and specific to DNA.The chromosome numbers of the haploid male and female gametophytes were 31, respectively,and there were 62 in diploid sporophytes.Most of the chromosomes were either droplet or short bacilliform.In the meantime,the female gametophyte chromosomes were between 0.78 μm and 2.61 μm in size,larger than the males that were between 0.57 μm and 2.17 μm.Based upon the relative size of chromosome,the karyotypes of the female or male gametophyte chromosomes were primarily analyzed.All the results laid a solid foundation for a basic technique for localization of molecular markers on kelp chromosomes.

Abstract:The jumbo flying squid(Dosidicus gigas)is one of important economic cephalopods with statolith providing important ecological information.According to the statolith morphology of the squid caught in waters off Chile,Peru and Costa Rica from May,2008 to Oct,2009,the differences of statolith morphology and growth patterns were analyzed.It was found that the statolith morphological characteristics in different areas had statistically significant differences(P<0.05).The length index and only the ventral dorsal dome angle(DDA)angle index had significant differences.The result of the principal component analysis was that total statolith length(TSL)was the most significant indicator of statolith morphology.The significant indicator of statolith angle was rostrum angle(RA)in waters off Chile and Peru,and rostrum lateral dome angle(RDA)in waters off Costa Rica.The growth of various parts was synchronized and allometric during the growth process,and the changing tendency of morphology was narrow body,long and narrow rostrum and large dorsal tallied with the characteristics of pelagic cephalopods statolith.Statolith growth consisted of two phases.According to the data of rostrum lateral dome length(RDL),there were marked differences in morphology between TSL smaller and larger than 1 600 μm.Based on the data of the angle,there were marked differences in RA between TSL smaller and larger than 2 000 μm in waters off Costa Rica,and 1 800 μm in waters off Peru,and there were marked differences in RA in waters off Chile.The angle increased later than the length of statolith,so TSL of 1 600 μm might be regarded as an valid indicator of changes in water layer.

Abstract:The Bohai Sea is a semi-enclosed shallow sea and is an important spawning,nursery and feeding ground for many migratory species from the Yellow Sea.Currently,overfishing and environment degradation may have changed the community structure in the Bohai Sea.The decline in the biomass,species composition,and size spectrum indicates a degradation of the Bohai Sea ecosystem.At the same time,the mean trophic level at high trophic level declined faster than global trend.So,it is very necessary to re-understand the feeding relationship in the Bohai Sea.Based on the data collected from bottom trawl surveys conducted in August and October of 2009 in the Bohai Sea,23 kinds of fish species,not including silver pomfret Pampus argenteus, and 7263 stomach samples were analyed.According to stomach analysis,the cluster analysis,of which 60% of similarity level was used as criterion,was used to study the functional groups and their major species of fish assemblages in the Bohai Sea.The results suggested that seven functional groups were divided among fish assemblages in the Bohai Sea,that is zooplantivores,omnivores,benthivores,shrimp predators,shrimp/fish predators,piscivores and generalist predators.In China coastal seas,the trophic structure of the Yellow Sea and Bohai Sea was similar and they belong to a large marine ecosystems,so variations in their fisheries resources relate closely with each other.Although according to the biomass,zooplantivores,omnivores and shrimp/fish predators were all major functional groups in August and October,there were some remarkable seasonal differences between two months.There were seven functional groups in August and six functional groups in October.The most important is that the proportion of each functional group was different.In August,zooplanktivores functional group accounted for larger proportion,but coming into October,the proportion of zooplanktivores functional group substantially declined,and the proportion of omnivores,piscivores and generalist predators functional groups increased.Fish assemblages at different ontogenetic phases was the major reason causing those differences.Since most marine species in the Bohai Sea are migratory species,which come into the Bohai Sea in spring and leave in late autumn,the further study on the difference of functional groups should take into account seasonal migration of fish assemblages.The results also showed that there were 5 major species:small yellow croaker Pseudosciaena polyactis, Spanish mackerel Scomberomorus niphonius, gizzard shad Clupanodon punctatus, silver pomfret and half-fin anchovy Setipinna taty in August,small yellow croaker,rednose anchovy Thrissa kammalensis, silver pomfret, gizzard-shad and half-fin anchovy in October,respectively.According to their diet composition, Coscinodiscus sp., Calanus sinicus, Euphausia pacifica, Acanthomysis longirostris, Acetes chinensis, Maeruran larva, Alpheus japonicus, Chaeturichthys hexanema, small yellow croaker,gastropoda and bivalvia were main prey species in the Bohai Sea, but now,anchovy and crab are not the main prey species.

Abstract:The possibility of refrigeration(4 ℃)of early larvae of the mussel Mytilus coruscus was examined in the present study.The effect of larval density on the refrigeration of M. coruscus was also investigated in three different culture batches.After refrigeration,larvae were transferred to 18 ℃,and survival rates and shell growth of larvae were investigated.The present results showed that the average survival rates of early larvae were higher than 95%,and both shell length and shell height showed a significant increase during the 1 month refrigeration period.Larval densities of different culture batches had a different effect on larval survival and shell growth during refrigeration,indicating that larval density may be an important factor for larval refrigeration.After larvae were transferred and cultured at 18 ℃ for three weeks,survival rates of refrigerated larvae decreased to 56%,which was lower than that in control larvae(75%).In contrast,the shell growth rate of refrigerated larvae was higher than that of control larvae.Thus,refrigeration can be used as an effective method of storing larvae of M.coruscus for use in field of mollusk larval biology and improvement of seed production techniques in aquaculture industry.

Abstract:In the present study 14 morphological traits(e.g.,total length,standard length,eye diameter)and 20 truss network characters were measured with different populations of Coilia nasus (CN),which were collected from Lvsi(LS) and Dasha fishing ground(DS)of the Yellow Sea,Chongming island(CM)of the Yangtze River estuary,Wuhu section in the Yangtze River(WH),Zhoushan Islands(ZS)in the Qiangtang River stuary,and Dongying section in the Yellow River(HH).Morphological differences between male and female C.nasus were analyzed by One-Way ANOVA analysis,principal components analysis and discriminant analysis,while morphological features of different populations were also comprehensively analyzed by Kruskal-Wallis H test,principal components analysis and discriminant analysis.Results indicated that the sexual size dimorphism was not significant in C.nasus, and there were no significant differences between male and female individuals except relative fatness,body depth at dorsal,body depth at anus,caudal peduncle depth and other 5 truss network characters.Additionally,cephalic traits among LSCN,DSCN,CMCN and WHCN were similar,while those of ZSCN and HHCN were relatively unique.The intergraded morphological features of former four populations(LSCN,DSCN,CMCN and WHCN)were significantly different from the remaining two populations(i.e.,ZSCN and HHCN),suggesting that the latter might be relatively independent and might have weak connectivity with the former populations.

Abstract:Two salinity concentrations(salinity 12,salinity 25)and a control group of fresh water were set up in the experiment.The samples were respectively taken at 0,3,6,12,24,48,72,96,and 144 h to study the effects of salinity changes on the hemolymph biochemical parameters of the female parent Chinese mitten crab (Eriocheir sinensis).The results showed that the values of total protein(TP) in salinity concentrations were significantly higher than that of the control group during the first 6 hours(P<0.05)while the values of TP in two salinity concentrations reached the same level and kept a little higher than that of the control group after 96 hours.The values of glucose(GLU)increased with the increasing of salinity concentration,and the values of GLU both increased first and then declined in the salinity concentrations.The values of GLU in salinity 25 reached the maximum level at 72 h and were significantly higher than that of the other two groups (P<0.05).The values of triglycerides(TG)in salinity 12 declined gradually,and were significantly lower than that of control group during 6-144 h(P<0.05),yet were significantly lower than that of salinity 25 after 72 h(P<0.05).The values of TG in salinity 25 declined first and then increased,and reached the same level as control group after 72 h.The values of alkaline phosphatase(ALP)both increased first and then declined in the two salinity concentrations.The values of lactate dehydrogenase(LDH) in the two salinity concentrations both reached the maximum values at 3 h and reached the minimum at 12 h.The result showed hemolymph TP,GLU,and TG all changed significantly during travelling from fresh water to saline water in parent Chinese mitten crab.It could be concluded that(1) the parent Chinese mitten crab enhanced the process of energy metabolism to deal with the sudden change of salinity and increased the use of lipids and carbohydrates as energy source.(2) the parent Chinese mitten crab first regulated protein metabolism in response to the changes of external osmotic pressure and finally adapted to the high-salinity water.

Abstract:The aquaculture of the sea cucumber Apostichopus japonicus (Echinodermata, Holothuroidea) has been growing rapidly over recent years in China in response to increasing consumer demand.Indeed,it has become an important sector of the marine industry in Northern China.However,with rapid growth and the use of non-standard practices and culture techniques,epidemic diseases of A. japonicus now pose increasing problems to the industry.Therefore,the healthy aquaculture of A. japonicus is important.For a reasonable evaluation of selenium effect on sea cucumber aquaculture,using laboratory tests to simulate the sodium selenite treatment and virus infection conditions,the detection and observation of the sea cucumber body cavity fluid immune enzyme changes,pathological changes and the relative rate of protection were made.The results showed that:the change of immune enzymes in coelomic fluid of sea cucumbers under simulated sodium selenite treatments and bacteria infected conditions was tested in order to reasonably evaluate the influence of selenium on aquaculture diseases.Results indicated that the activities of superoxide dismutase(SOD),glutathione peroxidase(GPx),lysozyme(LYZ),phenoloxidase(PO)and alkaline phosphatase(ALP)in coelomic fluid rose after sodium selenite treatments were enhanced.However,SOD,GP-X and LYZ activities first ascended and then declined,and PO and ALP activities showed continued rise under additional pathogen injection into sea cucumbers,but the increasing extent of ALP activity was reduced along with increased sodium selenite concentration,and total diseased incidence rose and relative percent survival decreased under the severe sodium selenite treatment.This suggested that applying sodium selenite with moderate concentration could enhance immunity of sea cucumber to bacterial infection,but infecting also aggravated immune damage of sea cucumber by sodium selenite stress.Therefore,the diseases of cultured sea cucumber can be alleviated by optimized use of selenium.

Abstract:The objective of this study was to determine the impact of upstream exercise training on feeding efficiency,growth,and nutritional components of juvenile tinfoil barb Barbodes schwanenfeldi (weight 75.21?2.82 g).The experiment included two stages,1-23 d and 23-45 d.After water current treatment(0 BL/s,0.7 BL/s,2.0 BL/s)for 45 d,the daily feeding ratio(FR)increased significantly with increasing water velocities.The maximum values of the body weight specific growth rate(SGR),body length SGR and feed conversion rate(FCR)were in the water current of 0.7 BL/s,the second maximum values of those were in 0 BL/s and the minimum values were in 2.0 BL/s,with significant differences among the three(P<0.05).No significant difference in crude ash and water contents in muscles was observed among the treatments with various water velocities(P>0.05).The protein contents of fish muscles increased greatly with the increase of water velocities,while the lipid contents of muscles dropped with increasing water velocities.At the end of the experiment,the contents of total amino acid(TAA),essential amino acid(EAA),and delicious amino acid of the fish treated with the water velocities of 2.0 BL/s were 82.63%,34.34%,and 33.50%,respectively,being significantly higher than respective values of controls(78.27%,32.6%,30.63%)(P<0.05).Our result indicated that the lower water currents(0.7 BL/s)could effectively promote growth of juvenile tinfoil barb,improve feed conversion rates,and increase protein contents of fish muscles.The exercise training under the high flow(2.0 BL/s)was unsuitable to growth,but it could increase the contents of EAA and delicious amino acids in muscles of juvenile tinfoil barb.The result could provide basis to improve culturing conditions and nutritional quality of tinfoil barb B. schwanenfeldi.

Abstract:A 60-day feeding trial including diets with two protein levels(22%,28%),two lipid levels(10.0%,14.0%)and two digestible energy levels(12.56 kJ/g,14.23 kJ/g)designed with three replications was conducted to investigate the growth,nutrient utilization and body composition of juvenile channel catfish.Four hundred and eighty fish(initial weight,141.5?1.0 g)were randomly distributed into 24 tanks(3.0 m?0.8 m?0.8 m)at a rate of 20 fish per tank and fed three times daily.Fish were fed respectively to apparent satiation by experimental diets named P28L10E14.23,P28L14E14.23,P22L10E14.23,P22L14E14.23,P28L10E12.56,P28L14E12.56,P22L10E12.56 and P22L14E12.56.Final weight,weight gain,specific growth rates(SGR)and feed conversion ratio(FCR)were not significantly affected by dietary protein or dietary lipid or dietary digestible energy(P>0.05),but were significantly affected by a dietary protein?lipid interaction(P<0.05),and extremely significantly affected by a dietary protein?lipid?digestible energy interaction(P<0.01).With the protein/energy ratio increasing,it took an increasing trend to final weight,weight gain and SGR(P<0.05),except that fish fed diet P28L10E12.56.The digestibility of dietary protein,lipid,energy and dry matter is increasing when dietary digestible energy decreased(P<0.05)and dietary lipid increased(P<0.05). With the dietary protein decreasing,it took a decreasing trend to the digestibility of dietary protein,energy and dry matter(P<0.05).The digestibility of dietary protein,lipid,energy and dry matter is increasing by dietary lipid levels(P<0.05).Nitrogen retention was significantly increased as dietary protein levels decreased(P<0.05),lipid retention decreased significantly with dietary digestible energy and lipid levels decreasing(P<0.05),protein efficiency ratio(PER)was significantly increased as dietary digestible energy decreased(P<0.05).Carcass protein and lipid were not significantly affected by dietary digestible energy concentrations(P>0.05);however,carcass lipid tended to improve(P=0.066) as dietary digestible energy levels increased.The results of this study indicated that the diet containing 28% protein with 14% lipid and 12.56 kJ/g digestible energy is optimal for growth of juvenile channel catfish(150 to 300 g weight).However,group P28L10E14.23 and P22L10E12.56 got second best weight,highest nutrient utilization and best body composition of juvenile channel catfish.It also indicates that lipid saved protein in diet of juvenile channel catfish.

Abstract:A feeding experiment was conducted to determine the dietary requirement of threonine of juvenile Japanese seabass(initial average weight 8.00?0.20 g).Six isonitrogenous and isoenergetic semipurified diets were formulated to contain 41.83% crude protein,19.68% kJ/g gross energy and six levels of threonine 0.75%,1.03%,1.36%,1.67%,2.04% and 2.31%(dry matter basis)at about 0.35% increment(diets 1-6).Each diet was randomly assigned to triplicate groups of 30 fish and fed to apparent satiation by hand twice daily(06:00 and 17:30)for 8 weeks in floating sea cages.The water temperature fluctuated from 26 to 32 ℃,salinity from 22‰ to 28‰ and dissolved oxygen was approximately 7 mg/L during the experimental period.No significant differences in survival were found among dietary treatments.Weight gain rate(WGR)significantly increased with increasing dietary threonine from 150.3 to 256.9%(P<0.05),and thereafter showed a declining tendency.Nitrogen retention(NR)significantly increased with increasing dietary threonine from 13.18% to 26.36%(P<0.05), same as above,declined.No significant differences in body composition were found among dietary treatment.On the basis of either WGR or NR,the optimum dietary threonine requirements of juvenile Japanese seabass were estimated to be 1.77% of diet(4.21% of dietary protein)and 1.88% of diet(4.47% of dietary protein),respectively,using second-order polynomial regression analysis.

Abstract:There are over 20 years of history of shellfish and seaweed polyculture in Sungo Bay.There had not been reported the outbreak of red tide in the Bay.However,in May 2011,there occured large scale red tide outbreak,which almost spread over the total bay,and which caused higher mortality of cultivated shellfish.It is very important to understand the cause of red tide and to provide data for future environmental protection and aquaculture management.We just carried out one survey of environment monitoring before the outbreak of the red tide.Therefore,in this paper,the distributions of sea water temperature,salinity and dissolved nutrients were investigated in Sungo Bay in April 2006 and 2011,so as to understand the cause of the outbreak of red tide.The results showed that the concentration of dissolved inorganic nitrogen(DIN),phosphate(PO₄^3-) and silicate(Si) in Sungo Bay of 2011 was 5.6,3.2 and 1.3 times of the same period in 2006, respectively.The mole ratio of DIN/P,Si/P and Si/DIN was (66.33?47.16),(35.12?21.44)and(0.82?0.77),respectively,which was seriously deviated from the Redfield ratio.Dissolved nutrients showed obvious block distribution,their horizontal distribution was characterized by a concentration decrease from the open sea to the inner bay,and there were two sub-peak values near the Yatou River and Bahegang areas,the isolines were almost overlaps with low-salinity isolines.The probable causes of red tide outbreak were discussed from four aspects including nutrients,hydrological characteristics,kelp and temperature.

Abstract:In order to study the diversity of eukarytic nanoplankton in the sea area for scallop culture,and clarify the relationship between eukaryotic nanoplankton and transmission of zhikong scallop (Chlamys farreri) acute viral necrosis virus(AVNV),seawater samples were collected monthly in 2009 and 2010 from Qingdao Liuqing River Bay’s sea area.3-25 μm plankton components were filtered and amplified 18S rDNA variable region sequences from filtered samples were analyzed by DGGE technique.The results show that the main eukaryotic nanoplankton in the sea area included Dinozoa,Ciliophora,Euglenozoa,Haptophyta,Ochrophyta,Labyrinthulomycota,Cryptista,Choanozoa,Amoebozoa and Cercozoan.The amount of Dinozoa and Ciliophora was the highest at 41% and 38.2%,respectively.The cluster analysis based on mensal DGGE bands shows that the plankton community from May to November 2009 is similar in the diversity of eukarytic nanoplankton.According to the studied results on scallop AVNV,Skeletonema costatum was taken to be a vector of transmission of AVNV,and it distributed during the period of scallop massive death.However,the role of Dinozoa and Ciliophora during the transmission of AVNV has yet to be determined.

Abstract:High content of cadmium in laver has seriously affected the edible safety,export and industry development of seaweed in our country.However,only total cadmium content was detected by present method used worldwide and the total cadmium was used to evaluate the food safety of the laver which may overestimate the toxicity of the cadmium in laver.Because there are different cadmium forms in laver which have different biological toxicities,the speciation analysis of cadmium in the laver is very urgent.However,studies on the cadmium speciation analysis in seaweed are very scarce at present.In present experiment,we first analyzed the different cadmium forms in laver(Porphyra haitanensis and Porphyra yezoensis) which have high Cd accumulation capability by using size exclusion chromatography-high performance liquid chromatography-inductively coupled plasma mass spectrometry(SEC-HPLC-ICP-MS).The result showed that three Cd species including Phytochelatins(PC)₃-Cd,glutathione(GSH)-Cd and one small molecule Cd species were detected in the deionized water extraction of the laver. In vitro wholebionic digestion model was used to determine the main cadmium forms in laver under the action of saliva,the acidity of stomach and intestine with inorganic and organic components and digestion enzymes.Two unknown Cd species with small molecule were detected in whole-bionic digestion of gastric extracts,and the retention time of main species was 24.2min.Two Cd species was detected in whole-bionic digestion of intestine extracts,and the main species was(PC)₃-Cd.However,further study is needed to study the metabolic characteristic of(PC)₃-Cd in the biology.Present study further proved the main organic cadmium species in seaweed and this has provided important basis for food safety evaluation of the laver.

Abstract:Quality changes and shelf-life of Antarctic krill were investigated by testing the indexes of dressing percentage,chemical(pH,TVB-N,TBARS,Ca² -ATPase activity)and sensory evaluation at the frozen temperature(-8,-18 and -28 ℃).The results showed that sensory evaluation of Antarctic krill obtained significant correlations with frozen time and frozen temperature(r=0.982 and 0.981 respectively),sensory evaluation was unaccepted on 20^th day at -8 ℃,75^th and 120^th day were unacceptable for -18 and -28 ℃ respectively.Dressing percentage exhibited significant correlations with frozen time(r=0.953), dressing percentage were 31.62%,31.21% and 34.52% at the end of the shelf-life (sensory evaluation unaccepted)at -8,-18 and -28 ℃,respectively.No significant correlations were found between pH and frozen temperature,and pH, consequently,was not considered as the suitable parameter for reflecting quality changes of Antarctic krill under frozen storage.However,pH increased as time extended, pH got 7.94,7.99 and 7.84 at the end of shelf-life respectively.Significant correlations were obtained between TVB-N,TBARS and frozen time(r=0.944 and 0.935), whereas,only frozen temperature at -8 ℃ has good correlations when TVB-N, and frozen temperature at -18 and -28 ℃ attained strong correlations with TBARS,TVB-N and TBARS reached 21.43,20.49,19.74 mg/100 g and 0.88,0.78,0.66 mg MA/kg at the end of the shelf-life at three frozen temperatures respectively.Those results were lower than the limitation.Ca² -ATPase activity decreased sharply with significant correlations with frozen time(r=-0.929).Changes of sensory evaluation,dressing percentage,TVB-N,TBARS and Ca² -ATPase activity were sensitive and had significant correlations with frozen time,therefore they could be considered as right testing indexes for Antarctic krill at frozen temperature.So shelf-life of Antarctic krill at three frozen temperature,based on the testing indexes and sensory evaluation,was estimated at 20,75 and 120 days respectively during the whole study.