• Volume 39,Issue 12,2015 Table of Contents
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    • >ROUNDUPS
    • Progress on in situ aquaculture of marine sponges with medicine potential

      2015, 39(12):1904-1911. DOI: 10.11964/jfc.20150509887

      Abstract (2311) HTML (0) PDF 1008.64 K (1994) Comment (0) Favorites

      Abstract:Marine sponges contain many structurally diverse bioactive compounds and are the best marine bio-resources for pharmaceutical development.But the "supply issue" of sponge material hampers their commercial production.Several strategies were proposed to resolve the supply issue. In situ sponge aquaculture was marked as one of the most reliable strategies after decades of studies.In this paper,we reviewed cases of in situ sponge aquaculture in the past 20 years and summarized important factors of the strategy,including the attaching methods,feeding,sizes of the explants,flow rates and suspending depths.The main points are:1.explants should be securely fixed; 2.feeding canals should be unobstructed; 3.rich POC with size<8μm in farming areas; 4.water flow should be moderate; 5.explant size should be moderate; 6.appropriate light; 7.some bioactive products are sensitive to circumstance.Most of the cases showed that farming operations had little influence on the accumulation of bioactive compounds.Our progresses in this field suggested that it is feasible to scale up in situ sponge aquaculture in our country to resolve the supply issue.We also presented three problems that would be encountered in the future:1.transplanting between areas with large environmental variations; 2.diseases and predators; 3.breeding of sexual propagated progenies.

    • >PAPERS
    • The preferred water velocity behavior of six Cyprinids with different feeding habits

      2015, 39(12):1807-1816. DOI: 10.11964/jfc.20150409804

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      Abstract:The aims of present study were to investigate the effects of feeding habits on preferred water velocity behavior of the cyprinidae fish,six species of cyprinidae fish that have different feed preferences were used as the research subject.To achieve our goals,six cyprinids include silver carp(Hypophthalmichthys molitrix) and bighead(Aristichthys nobilis) that are the filter-feeding fish,grass carp(Ctenopharynodon idella) and qingbo(Spinibarbus sinensis) that are the vegetarian,and the crucian carp(Carassius auratus) and goldfish(C.auratus) that are the omnivorous fish.Firstly,each of six fish species were videoed individually(N=12 for each species) in a self-made preferred water velocity determining device,i.e.,a 1.5 meters long conical raceway with water speed gradually increasing from 11.86 to 65.45 cm/s at(25±1.0)℃.The videos were then analyzed by Ethovision XT19 and the percent time stayed(Pt),frequency(F) and the average duration of each fish stayed(T) in each water velocity interval were all calculated.Our results showed that(1) the preferred water velocity behavior of the six fish species are presented into two kinds of trends.If an individual of a given species stayed mainly in the lowest water velocity interval(Pt>50%),the fish individual is considered Type Ⅰ.Otherwise,the fish is considered Type Ⅱ.At the same time,the experimental results indicated that feeding habit has a significant effect on the water velocity preference behavior of the experimental fish.Compared to the Type I of omnivorous habit fish including the crucian carp and goldfish and herbivorous fishes including grass carp and qingbo,the Type Ⅰ of filter-feeding fish including the silver carps and bighead showed more significant preference of the lowest water velocity interval.The Type Ⅱ of filter-feeding fish preferred stay in higher water velocity than the omnivorous habit fish.However,the Type Ⅱ of herbivorous fishes including the grass carp and qingbo showed no preference to the water velocity intervals,but it had higher F values in middle water velocity intervals.The present study suggested there is a sharp variation in the water velocity preference behavior of six experimental fish species.This water velocity preference behavior for each species could be divided into Type Ⅰ and Type Ⅱ.In addition,feeding habit has a significant effect on the water velocity preference behavior of the experimental fish.

    • Study on the relationship of fish's vision angle with nearest neighbor distance under laboratory conditions

      2015, 39(12):1817-1825. DOI: 10.11964/jfc.20150409831

      Abstract (2639) HTML (0) PDF 1.50 M (2078) Comment (0) Favorites

      Abstract:Data showed a rule that the nearest neighbor distance(NND) decreases as the vision angle of own fish increases in Pseudorasbora parva school.To explore whether other fish schools follow the same rule,30 individuals of Hemigrammus rhodostomus have been selected as a comparative object,which was smaller in body length and their average body length was(20.3±0.2)mm.The size of the aquarium length,width and height were 78.0 cm,52.0 cm and 65.0 cm respectively.The water depth was 5 cm.A video camera was set up to record the position of fish from overhead of aquarium in lab.Two-dimensional location data of each individual can be selected from the records in time sequence.Two parameters,NND and vision angle,were selected for characterizing the structure and to explore the relationship in different fish schools.Results show that:1) the vision angles of P.parva and H.rhodostomus all remained within the 80°,that is,the vision angle of own fish observing the neighbors is not greater than 80°.2) the vision angle range that neighbor fish occupies the own fish view doesn't increase as the body length increases in different species fish schools.3) If NND remains stationary,the maximum vision angle(neighbor fish occupies the own fish view) and NND have the relationship as yx=A,in which y is for vision angle(unit:degree), x is for NND(unit:BL),A is a constant and related with body length of individuals.The rule is applicable to P.parva and H.rhodostomus schools.4) When the NND is minimum between the own fish and neighbor fish,schooling is accomplished and maintained by vision angle.In other words,the vision angle is the main parameter to control the distance between each other and plays a dominant role.Lateral line and other sense organs may have their functions,but they might be less important.

    • Study on the bioremediation potential of Najas indica

      2015, 39(12):1826-1836. DOI: 10.11964/jfc.2015069904

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      Abstract:The aim of this paper is to investigate the bioremediation potential of Najas indica. In the present study, the removal rates of N. indica on nitrogen and phosphorus were analyzed at 4 planting densities(1, 2, 3 and 4 g/L) and 3 eutrophic water degrees(mesotrophic, eutrophic and utmost eutrophic), which detected the concentration of NH4-N, NO3-N, TN and TP. Besides, the inhibitory effect of N. indica on the growth of M. aeruginosa was studied by the analysis of the number of M. aeruginosa and the concentration of nutrients. The results showed that removal rates of N. indica on nitrogen and phosphorus were significantly high. At the planting density of 4 g/L, the removal rates of TN and TP were up to 99.50% and 93.45%, respectively, while there is no significant difference between different treatments. Eutrophic degrees have a significant effect on the removal rates of nitrogen and phosphorus. The uptake rates of N. indica on nitrogen and phosphorus were increasing as the nutrient increased, and the uptake rates of TN and TP reached the highest 1.11 and 0.15μmol/(g·h), respectively. In the utmost eutrophic group, the removal rates of TN and TP also reached the highest 99.46% and 90.75%, respectively, which were significant higher than other eutrophic levels. Meanwhile, N. indica had an obviously inhibitory effect on the growth of M. aeruginosa, and algal inhibiting rate reached 99.89% in the experimental group. The detection results of water quality showed that the concentration of TP and NH4 under co-culture condition was lower than control group significantly. Based on the study, N. indica presents a potential application for remediation of the eutrophic water ecosystem and prevention of the bloom caused by M. aeruginosa.

    • Effects of intermittent feeding on the development of the digestivesystem and morphological behavior for juveniles of Liza haematocheila

      2015, 39(12):1837-1851. DOI: 10.11964/jfc.20150309759

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      Abstract:A 22-day feeding trial was conducted to assess the compensatory growth response to different cyclic starvation and refeeding regimes in juvenile Liza haematocheila. The test was performed in the conditions of the water temperature:(19±2)℃, pH:7.2, salinity:3.5, the oxygen content was 6%,the same age(36 days), the similar size, the L. haematocheila juvenile were fed:twice a day,once a day,once 2 days,once 4 days,once 8 days(namely S0, S1, S2, S4, S8), cyclic feeding 20 d, sampling at 22 d. We measured morphological characters about the body weight, body length, body height, head length, length before anal and so on. The experiments were carried out using anatomy, Bonn's solution fixation, paraffin sections, H.E staining, optical microscopy techniques to observe the juvenile barracuda's structure, morphology of the digestive organs in different groups. The esophagus, stomach and intestines cortex height, tall columnar cells, wall thickness, muscle layer thickness and the size of the esophagus and intestinal goblet cells were measured. Using SPSS19.0 software for measurement data,we analysed the impact of intermittent starvation on their histology. The results showed:in terms of juvenile behavior, the cluster of S0 and S1 was strong, swift movement, the cluster of S4 and S8 was weak, when they were frightened, they were in sporadic distribution, and the movement was somewhat less. In terms of morphology, the individuals of S0 had the largest increase, almost with the same period the growth of juvenile fish in the nursery pond, individuals of S1 were smaller than S0, there was a significant difference between the groups in the weight in both S0 and S1; S4, S8 had varying degrees of damage,with a big head and a little body,stomach volume was reduced, wall thinning; intestinal wall thinning transparent, mesenteric fat disappeared because of atrophy. Liver volume was significantly reduced with the color change from the original pink to crimson yellow.In tissue structure, S0 inter-group's tissue has somewhat changed, but it was not obvious. S1, S2 had a significant increase in the mucus cells; the gastric cells developed, but the secretory granules decreased,intestinal folds height decreased significantly and epithelial cell height reduced, the striated border height in S0 and S1 did not change significantly;from S1 to S4,the striated border height gradually became smaller, even irregular, S4, S8 group striated border height reduced significantly. In addition, obvious changes could be found in gastrointestinal mucosa of S8 group with fewer endocrine granule,intestinal brush border broken off, height of columnar cells reduced significantly from the front to the rear of intestine,goblet cells was significantly smaller in volume, liver cell shrinkage, reducing the number of lipid vacuoles, cell boundaries obvious and irregular, pancreatic acinar narrow, irregular arrangement. The results showed that when juvenile L. haematocheila at intermittent short-term starvation,the fish could adjust itself accordingly in tissue structure, the compensation effect existed, but when the intermittent hunger had a certain period of time,and then the digestive structure will display some irreversible phenomenon.

    • Effects of different dietary carbohydrate levels on growth and glucose tolerance ability in fishes of different feeding habits

      2015, 39(12):1852-1862. DOI: 10.11964/jfc.20150209737

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      Abstract:To study the effects of different dietary carbohydrate levels on growth,glucose metabolism indicators and tolerance ability in fishes of different feeding habits after an 8-week feeding trial,this experiment was conducted taking Tilapia(GIFT, Oreochromis niloticus),Derbio(Trachinotus ovatus) and Cobia(Rachycentron canadum) as the research objects,dextrin as the sugar source,three levels of dietary carbohydrate for each fish at low,medium and high levels(CL,CM,CH; Tilapia:20%,30%,40%; Derbio:13%,26%,39%; Cobia:12%,24%,36%) respectively.The results showed that:the different carbohydrate levels had no significant effect on survival rate of Tilapia(P>0.05); The feeding conversion rate(FCR) showed an increasing trend after the first decline with elevated levels of dietary carbohydrate and the CL group in Tilapia was the highest(P<0.05); The weight gain rate(WGR) and specific growth rate(SGR) were all the highest in CH group and significantly higher than the CL group(P<0.05).The survival rate in CH groups of Derbio and Cobia were significantly lower than the other groups(P<0.05).However,the WGR and SGR in CM were the highest significantly(P<0.05).The FCR first increased,then decreased with dietary carbohydrate levels elevated and the CM lowest groups were the lowest(Tilapia:1.47,Derbio:1.61,Cobia:1.49)。Different dietary carbohydrate levels have different effects on glucose metabolism indicators of fish.With rising levels of dietary carbohydrate in Tilapia,the plasma glucose,insulin,hepatic/muscle glycogen and triglycerides of CH group were significantly higher than the other groups(P<0.05).The plasma glucose,insulin,hepatic/muscle glycogen,triglycerides of CH groups in Derbio and Cobia are the highest,but there was no significant difference in plasma glucose and insulin between CL and CM groups in Derbio(P>0.05).There were also no significant differences in plasma glucose and insulin levels of CM and CH in Cobia(P>0.05).The glucose tolerance test(GTT) results showed that:(1) After injection of glucose,the plasma glucose levels of Derbio and Tilapia groups reached the peak at 1 h(P<0.05) and returned to the initial level at 12 h while the Cobia until 24 h after a peak at 3 h.(2) The plasma insulin levels in tilapia and cobia groups rose slowly after the injection of glucose and reached the highest level at 3 h(P<0.05),while the lever in Derbio group was significantly decreased within 1 h(P<0.05).(3) The glycogen levels in Derbio and Tilapia increased slowly and reached the peak at 3 h and 6 h respectively(P<0.05) while the Cobia declined within 1 h.(4) after the injection of glucose,The triglyceride levels in Tilapia and Derbio reached the peak at 3 h and 6 h after injection of glucose respectively(P<0.05) while the Cobia decreased significantly within 1 h(P<0.05).The results of this study suggest that dietary carbohydrate levels have varying degrees of effects on the growth,glucose metabolism indicators,glucose utilization and tolerance of three feeding habits,fish.The omnivorous Tilapia can utilize the dietary carbohydrate better than carnivorous fish.The glucose tolerance ability of omnivorous Tilapia is the strongest,followed by Derbio the intermediate,and Cobia the lowest.

    • Cloning and expression analysis of BLT1-like genes from zebrafish(Danio rerio)

      2015, 39(12):1753-1762. DOI: 10.11964/jfc.20150609926

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      Abstract:In order to research the functions of BLT1 in the development and vaccination process of zebrafish,two leukotriene B4 receptor 1-like(BLT1-like) genes, BLT1-like1 and BLT1-like2,from zebrafish were cloned,which encoded 339 and 356 amino acids,respectively.Through sequence and structure analysis,it was found that both of the two proteins belong to rhodopsin subfamily of G protein coupled receptors(GPCR),with typical features of GPCR and have a moderate identity of above 31% with human BLT1.Additionally,when fused with enhanced green fluorescent protein(EGFP) and expressed in CHO cells,a good membrane-bound property was found.And Western blotting experiment verified their specific interactions with human BLT1 polyclonal antibodies.Besides,the results of RT-qPCR showed that during the embryo development of zebrafish,the expression of BLT1-like1 was up-regulated significantly at 12 h,which was 18 times higher than that of 1 h.While the expression level of BLT1-like2 changed sharply at 24 h,which was 34 times higher than that of 1 h.In addition,both of the two genes had a relatively high expression level in the heart and liver,while with a relatively low expression level in the intestine,skin and eye.Conclusively,our study indicates that there might exist more than one BLT1 gene in zebrafish and this will be helpful to clone and characterize BLT1 genes from other fishes.

    • Molecular cloning and expression analysis of Foxp1a/b from Nile tilapia(Oreochromis niloticus)

      2015, 39(12):1763-1772. DOI: 10.11964/jfc.20150309814

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      Abstract:To investigate whether the mRNA expression of Nile tilapia(Oreochromis niloticus) Foxp1a and Foxp1b are involved in the lymphocyte activation and regulated by 17β-estradiol(E2) level in vivo,the coding sequences and mRNA expression patterns of OnFoxp1a and OnFoxp1b were characterized and analyzed by Real-time PCR. OnFoxp1a has an open reading frame 1710 bp encoding 569 aa,while OnFoxp1b with 2040 bp encoding 679 aa.Both of the putative OnFoxp1a/b contain a C2H2 zinc finger domain,a leucine zipper-like domain(V-x(6)-L-x(6)-L-x(6)-L) and a winged-helix/fork head domain,which are typical motifs of Foxp subfamily.Compared with OnFoxp1a,OnFoxp1b shows a higher amino acid identity(77.4% versus 55.0%) to mammalian Foxp1.Phylogenetic analysis reveals that OnFoxp1a/b together with the other known vertebrate Foxp1 form a different clade from Foxp2,Foxp3 and Foxp4.Meanwhile,OnFoxp1a/b separately form a fish-specific clade and OnFoxp1b is further clustered with Foxp1 from the higher vertebrates,which supports that OnFoxp1b has a closer relationship with mammalian Foxp1.The expressions of OnFoxp1a/b were detectable in all examined tissues.The highest mRNA expression of OnFoxp1a was observed in the testis,while OnFoxp1b in the heart.Moreover,the moderate expression of OnFoxp1b was also observed in the immune-related tissues,such as spleen,kidney,gills and intestine.Stimulation of peripheral blood mononuclear cells with PHA(50μg/mL) and PMA(50 ng/mL) led to a significant increase of OnFoxp1b mRNA expression at 6,12 and 24 h,respectively,while no significant changes of OnFoxp1a mRNA expression were observed except stimulation of PHA at 24 h.These results imply that the homologous Foxp1 in lower vertebrate is involved in lymphocyte activation.After 24 h treatment of 6-month male(XY) tilapias with estrogen(17-beta-estradiol,E2),the expressions of OnFoxp1a/b were significantly up-regulated in the intestine and kidney but not in the spleen.Taken together,our results suggest that both of OnFoxp1a/b coded by two different genes are the orthologues of mammals and have potential disproportionate functions.Moreover,the mRNA expression patterns of OnFoxp1a/b are related with the lymphocyte activation and regulated by E2 level in vivo.This study not only provides scientific data for the research on the molecular evolution of Foxp subfamily members in lower vertebrates,but also will promote further study of the fish molecular immune response.

    • Effect of Vibrio alginolyticus infection on immune function of Charybdis japonica hepatopancreas

      2015, 39(12):1863-1871. DOI: 10.11964/jfc.20150409811

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      Abstract:Charybdis japonica is widely distributed along the coasts of China,Japan,Korea and Southeast Asia.Desired for its good taste as well as being rich in protein and low in cholesterol,this crab is currently one of the most important commercially farmed crabs in the world due to its rapid growth and easy culture methods.During the last two decades with the constantly expanding scale of aquaculture and the rapid development of intensive culture techniques in China,the environmental and health problems in C.japonica cultures have resulted in outbreak of infectious diseases.The worldwide shrimp/crab culture industry has suffered significant economic losses due to diseases mainly caused by vibrios,particularly Vibrio alginolyticus,one of the most detrimental pathogens widely disseminated in crabs.In recent years,the treatment of bacterial diseases of aquatic animals has relied on application of large quantities of antibiotics,which not only causes development of drug resistant pathogens but also presents a health risk to humans.Improving immunity and disease resistance in crustaceans is one of the fundamental measures for preventing and controlling disease.In this study,the pathogenic mechanism of a Gram-negative bacterium Vibrio alginolyticus in the stone crab Charybdis japonica was explored by investigating activities of enzymes related to innate immune function during infection,i.e.phenoloxidase(PO),superoxide dismutase(SOD) and lysozyme(LSZ).Four groups of crabs were tested by intramuscular injection of C.japonica:control group,normal saline; immunity group,0.5% polysaccharide; infected group,normal saline plus V.alginolyticus challenge 24 h later; immunized infected group,0.5% polysaccharide plus V.alginolyticus challenge 24 h later.After 6-12 h of exposure to V.alginolyticus,the activities of PO,SOD and LSZ increased in C.japonica hepatopancreas,but then decreased over longer infection time.Interestingly,enzyme activities in crabs treated with polysaccharides before V.alginolyticus challenge were higher than those in infected group,showing an immunoprotective rate of 72.73% at 7 days after exposure.This phenomenon suggested that the polysaccharides could enhance the organism's antiviral defenses by improving activities of immuno-enzymes.Morphological examination by transmission electron microscopy revealed significant damage in the hepatopancreas of V.alginolyticus- infected crabs,showing parts of the hepatopancreas epithelium and microvilli were reduced in number and size or damaged.Meanwhile,morphology of the mitochondria and rough endoplasmic reticulum(RER) changed.Moreover,heterochromatinized nuclei could be seen in hemocytes with ruptured nuclear membranes.The structure of hepatopancreas nuclei in immunized infected group was normal compared with that in infected group,and the microvilli arranged densely in neat rows.The lysosomes in hepatopancreas cell of immunized infected group increased; however,dropsical endoplasmic reticulum,thin cytoplasm and distorted mitochondria could still be seen.

    • Effect of acute temperature stress on serum cortisol and hematological physiology of gestated Sebastes schlegelii

      2015, 39(12):1872-1882. DOI: 10.11964/jfc.20141109567

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      Abstract:To explore the adaptability and restoring ability in water with mutant temperature,gestated Sebastes schlegelii were moved from normal temperature(16℃) to high(25℃) or low(7℃) temperature water,being exposed for 2 h,and subsequently transferred to original seawater of 16℃.Samples were collected at 0,6,12,24,48 and 72 h during recovery to detect changes of serum cortisol(COR) and hematological and physiological parameters of gestated Sebastes schlegelii.The data showed that acute thermal stress led to parturition behavior of two fish; It was noted that COR,glucose(GLU),globulin(GLB),glutamic-pyruvic transaminase(GPT),glutamic-oxaloacetic transaminase(GOT) and white blood cell(WBC) levels in serum increased significantly(P<0.05) whereas concentrations of total protein(TP),albumin(ALB),total cholesterol(TC) and triglyceride(TG) became lower obviously during recovery process after acute stress of 25℃ and 7℃(P<0.05).Besides,there was no difference in Ca2+,Mg2+ and P contents.Interestingly,red blood cell(RBC) and hemoglobin(HGB) levels arose remarkably after acute heat stress(P<0.05) while those were detected down-regulated by acute chilling stress(P<0.05).It was observed that thermal stress had a sharper effect on physiological status compared with acute chilling stress.Moreover,most indexes,except for COR and inorganic ions,did not restore to normal level after 72 hours.Our results suggest that acute temperature stress results in distinct impact on physiological function and metabolic levels of gestated Sebastes schlegelii,and even parturition behavior in advance.It is of high importance to monitor closely water temperature fluctuation,especially elevation,as for female fish entering the reproductive phase,in order to decrease injury induced by temperature stress during pregnancy.

    • Cloning and expression analysis of Esflol gene in Eriocheir sinensis

      2015, 39(12):1773-1779. DOI: 10.11964/jfc.20150409839

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      Abstract:The crustacean hyperglycemic hormone(CHH) family has been found only in arthropods currently,and plays significant roles in regulation of glucose levels,molting,stress response and a variety of physiological metabolic activities.We selected Esflol(Eriocheir sinensis flotillin-1 like,Esflol) as our object of study afer transcriptome analysis and gene expression profiling,to understand the importance of this family-crustacean hyperglycemic hormone(CHH),how to regulate glucose levels of the E.sinensis.According to the prompting of transcriptiome,a cDNA sequence encoding Esflol was cloned from hepatopancreas of E.sinensis by RACEs,and the results of tissue expression analysis were also obained.The results show that the open reading frame of Esflol consists of 1281 bp,encoding 426 amino acids without signal peptide.Typical domains of SPFH super family and PHB domain.Multi-sequence alignments analysis showed Esflol shared the higest identity with E.sinensis flotillin-1(57%).Tissue distribution of Esflol was detected by quantitative real-time PCR,although strong expression of Esflol was detected in hepatopancreas and muscles,and its expression could also be found in heart,gill,gut,ganglion and stomach,and in lower expression levels of brain.This study lays the foundation for sugar metabolic physiological mechanism research of E.sinensis,and also provides a reference for sugar metabolic physiological mechanism research of other aquaculture crustaceans.

    • Genetic parameter estimates of growth traits and flesh components in juvenile grass carp(Ctenopharyngodon idella)

      2015, 39(12):1780-1787. DOI: 10.11964/jfc.20150309787

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      Abstract:Aimed to access the genetic effect on growth traits and flesh components in juvenile grass carp(Ctenopharyngodon idella).Total of 288 juvenile grass carp at four months of age were random collected from artificial breeding program,and 273 of them were unambiguously assigned to sixteen full-sib families(from eight dams and nine sires) using twelve microsatellites.The contributions to the offspring by different families(full-sib and half-sib families) were showed with significant non-uniform distribution(P<0.01).Three growth traits(body weight,standard length,and condition factor) and two flesh components(protein and fat contents) of fish were detected in our study.The significant differences of three growth traits and protein content were detected among full-sib families and dam half-sib families(P<0.05),whereas,no significant differences of five traits were detected among sire half-sib families(P>0.05).The genetic parameters for these traits of juvenile grass carp were estimated using restricted maximum likelihood(REML) algorithm based on animal model.The heritability estimates for growth traits were 0.34 for body weight,0.33 for standard length,and 0.17 for condition factor,which were all significantly different from zero(P<0.05).Whereas,the heritability estimates for flesh components were 0.17 for protein content,and 0.20 for fat content,but not significantly from zero(P>0.05).Highly positive genetic correlation was found between standard length and body weight(0.82, P<0.01).Meanwhile,significantly positive genetic correlations were showed between condition factor to other traits studied except standard length(0.17-0.29, P<0.05).Therefore,selection for increased standard length of C.idella is expected to produce favorable improvement in body weight,but it may lead to unfavorable changes in condition factor and fat content.This should be taken into account in practical breeding programs of C.idella.

    • Oreochromis niloticus model of meningitis in Streptococcus agalactiae infection

      2015, 39(12):1883-1893. DOI: 10.11964/jfc.20150309771

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      Abstract:The meningitis was the characteristic clinical manifestation in Nile tilapia(Oreochromis niloticus) infected by Streptococcus agalactiae. To know the degree and extent of inflammation as well as the presence of necrosis in the brain,we build an intraperitoneal infection model and develop a new clinical and histopathological scoring system for S.agalactiae in Nile tilapia.43 healthy nile tilapias,were randomly divided into 4 groups:control group(n=10),low dose group:1.0×106cfu group(n=11),middle dose group:1.0×107cfu group(n=11),high dose group:1.0×108cfu group(n=11).Clinical symptoms and cerebral histopathological changes(cerebrum,optical lobe,cerebellum and medulla oblongata included)was oberserved in our study,we scored these three groups and obtained the best one.The infected nile tilapia died in second day post infection,however,neurological symptoms were not apparently observed in the dead fish.Survivors developed constant aberrant swimming,exophthalmia and corneal opacity.According to microscopical examination of four regions of the brain,large amount of bacteria stained bluish violet colonized the subarachnoid space and cerebral pia mater.Histopathology revealed the changes of leptomeningitis and meningoencephalitis,including congestion/hemorrhage,edema,loose and thickening in meninges,inflammatory cell neutrophilic leukocytes infiltration,superficial periplast of brain inflammatory cell infiltration and lysis spongy-structure,gliocyte hyperplasiain,and so on.Compared with the scores,we found that the group of 1.0×107cfu was the best dosage,which showed significant clinical symptoms,the minimum diversity value and the condition of the sick fish contributed to the observational study.We chose the dose of 1.0×107cfu to inject nile tilapia intraperitonealy to develop a model of S.agalactiae meningitis with the 100% success rate on the third day post infection.

    • Effects of 24-epibrassinolide on the agar synthesis and expression of genes involved in marine alga Gracilariopsis lemaneiformis

      2015, 39(12):1788-1798. DOI: 10.11964/jfc.20150309742

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      Abstract:The effects of 24-epibrassinolide on the expression level of two genes, pgm encoding phosphoglucomutase(PGM) and pmm encoding phosphomannomutase(PMM),involved in agar synthesis at different temperatures as well as the correlation between genes expression level and agar content were investigated in marine red alga Gracilariopsis lemaneiformis 981 strain.The open reading frames(ORF) of pgm and pmm were obtained by PCR,encoding 585 amino acids and 249 amino acids,respectively.The deduced amino acid sequences showed significant similarity to the pgm and pmm sequences of Chondrus crispus.Real time quantitative PCR technique was used to detect the relative expression levels of PGM and PMM.Results showed that the highest growth rate of G.lemaneiformis was observed under the treatment of 0.1 mg/L 24-epibrassinolide at 15 and 31℃,while the highest growth rate was at 0.5 mg/L 24-epibrassinolide treatment group at 25℃.The agar content and pgm expression of G.lemaneiformis were the highest at 0.5 mg/L 24-epibrassinolide treatment group at 15℃,and those of G.lemaneiformis was higher than the control and other treated groups when treated at 1.0 mg/L 24-epibrassinolide at 25 and 31℃.Besides,24-epibrassinolide could also improve pmm expression level at different temperatures.The results indicated that 24-epibrassinolide can improve the growth and agar synthesis of G.lemaneiformis,and pgm expression level is closely related with agar content,which may be useful in screening for high-agar-content strains.

    • Optimal design of Northern maoxia shrimp(Acete chinensis) stow net in coastal region of the East China Sea

      2015, 39(12):1894-1903. DOI: 10.11964/jfc.20141209588

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      Abstract:Model tests of two types of Acete chinensis stow nets,single anchor and single anchor beam,were conducted in this study.The effects of drag and expansion devices on these two stow nets showed that(1) the top/bottom or two sides of the mouth in Northern maoxia shrimp(Acete chinensis) stow nets adopted catenary cuts and assemblies,which was superior to plane assembly in stow net shape.(2) In the single anchor Acete chinensis stow nets,the top and bottom of the mouth adopted catenary cuts and assemblies; the horizontal expansion was increased from 15% to 30% and the height of net mouth was also increased when towing speed increased gradually in the range of 0.13-0.78 m/s.Under the same towing speed,the height of net mouth with catenary cuts and assemblies was greater than that of plane cuts and assemblies.In contrast with plane cuts and assemblies,the two sides of the single anchor beam stow nets adopted catenary cuts and assemblies; the height of net mouth was decreased slowly with the towing speed increasing,and in contrast with plane cuts and assemblies,it was increased by-5.6%-43.4% under the same towing speed in the range of 0.13-0.78 m/s.(3)The stow nets with the same main dimensions,same towing speeds and similar structures,which adopted catenary cuts and assemblies on top/bottom or two sides of the net mouth,were compared with the ones with plane assemblies; the result showed that the drag of net was increased gently when the towing speed increased from 0.13 m/s to 0.78 m/s.The stow nets with similar main dimensions and same towing speeds,which adopted canvas device expansion,were compared with the ones that adopted beam expansion; it presented the result that when the towing speed of 0.13-0.78 m/s increased,drag of net was increased significantly.(4)Single anchor Northern maoxia shrimp stow net model adopted catenary cuts and assemblies on top/bottom or two sides of the net mouth,while single anchor beam model,on two sides of the net mouth.Comparing incident flow area of the two models,it was shown that,at a towing speed rate of 0.13 m/s,there are 3.1% differences of incident flow area between the two,and at the towing speed rate of 0.78 m/s,the former is more than 3 times of the latter.

    • Prediction of Takifugu rubripes weight based on radial basis function neural network

      2015, 39(12):1799-1806. DOI: 10.11964/jfc.20150309788

      Abstract (2264) HTML (0) PDF 1.87 M (1843) Comment (0) Favorites

      Abstract:Takifugu rubripes belongs to the bony fishes,Tetraodontiformers,Tetraodontoidei,Tetraodontidae, Takifugu.It is distributed mainly in Japan of the western north Pacific,the Korean peninsula and China's coastal areas.Due to its appealing taste,rich nutrition,low fat content and numerous trace elements, Takifugu rubripes represents one of the fish species with high economic value.In recent years, Takifugu rubripes are farmed in large numbers in Dalian,Qinhuangdao,Tangshan,and Tianjin regions,and has become the main cultured species of puffer fishery in china.There existed large errors due to self-correlation between different phenotypic traits,non-linear relationship between some traits and body weight and the collinearity among independent variables,when the linear regression model was used to predict Takifugu rubripes weight.As a solution,a Takifugu rubripes weight prediction RBF neural network model,according to Artificial Neural Networks theory and Radial Basis Function model,was constructed with the phenotypic traits(including total length,body length,body depth,head length,length between eye and head,snout length,mouth width,eye diameter,space between eye and eye,caudal peduncle length,caudal peduncle depth,caudal peduncle breadth,body width,trunk length,trail length,body girth 1,body girth 2 and body weight) of 72Takifugu rubripes based on the nearest neighbor clustering algorithm,and the credibility of the neural network model constructed was tested by linear regression techniques.The results showed that the coefficient of determination R2 of RBF neural network prediction model and the linear regression model for Takifugu rubripes weight were 0.992(approximately 1) and 0.949,respectively.Obviously,the coefficient of determination R2 of RBF neural network prediction model was improved by 4.53% compared with the linear regression model.In addition,the collinearity diagnostics of linear regression,based on tolerance and variance inflation factor as well as maximum condition index and maximum variance proportions,indicated that there existed certain collinearity among independent variables and self-correlation between body girth 1,and body depth.The results suggested that the RBF neural network technique was an effective method to construct the prediction model of Takifugu rubripes,and the collinearity of the independent variables,in RBF neural network analysis,was eliminated and it has higher accuracy than linear regression prediction model.Weight prediction model based on radial basis function neural network provides a new method for accurate prediction of Takifugu rubripes weight.

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