• Volume 36,Issue 12,2012 Table of Contents
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    • Preliminary judgment of the antibacterial functions of two recombinant WSSV envelope proteins VP281 and VP31

      2012, 36(12):1901-1909. DOI: DOI:10.3724/SP.J.1231.2012.27778

      Abstract (2083) HTML (0) PDF 584.07 K (2445) Comment (0) Favorites

      Abstract:Abstract: White spot syndrome caused by white spot syndrome virus (WSSV) is the most severe epidemic virosis to shrimp culture industry in the world, resulting in tremendous economic losses. Virus envelope proteins play important roles in interacting with host cells, initiating virus infection or mediating virus intrusion. Studies about WSSV envelope proteins are numerous, but their functions haven’t been elucidated. In this study, by using a prokaryotic constitutive secretory expression plasmid as the expression vector, the recombinant Escherichia coli strain DH5α that could constitutively secrete WSSV envelope protein VP28, VP281 or VP31 were tried to be constructed. Recombinant DH5α that could constitutively secrete rVP28 and rVP281 were constructed successfully and were respectively named DhpVP28 DhpVP281. DhpVP281 grew much slowly compared with DhpVP28 and we guessed that the expression of rVP281 probably inhibited the growth of E. coli. However, recombinant bacteria constitutively expressing VP31 can not be obtained. In order to find out why recombinant bacteria that constitutively secrete rVP31 can not be constructed, recombinant bacteria BL21 (DE3) pLysS were constructed with pET-30a( ) as the expression vector and rVP31 was obtained in the form of inclusion body. After renaturation, the antibacterial activity of rVP31 was tested. The result showed that rVP31 has the antibacterial activity against Micrococcus lysodeikticus. These findings, reported for the first time, may increase the virology knowledge of WSSV.

    • Molecular identification of transplanted Hypomesus species in seven places

      2012, 36(12):1802-1808. DOI: DOI:10.3724/SP.J.1231.2012.28159

      Abstract (2419) HTML (0) PDF 517.87 K (2738) Comment (0) Favorites

      Abstract:The fishes of smelt genus Hypomesus lives in fresh water, brackish water and coastal seas,distributes in the Northern Hemisphere. Now, the Japanese smelt H.nipponensis and the pond smelt H.olidus are the common species and mainly distributed in the northeast region in China. Their body are small with silvery white. The life span of the fishes is short and theirs age of sexual maturity is above 1 year and they dies after spawning. They have strong adaptability and have been transplanted widely in China as the important commercial fishes. However, it is strange that there still exist disputation so far on which species of Hypomesus ever been transplanted widely in China. In this study, transplanted smelt collected from seven places locating in Heilongjiang , Xinjiang and Yunnan province are identified using CO I gene, which is a popular DNA barcoding for species identification in the world. Comparative analysis showed that CO I gene sequence from all above collected somelts shared more than 99% similiarity with that from H. nipponensis, which was published on the webs of GenBank and DNA barcoding Center. Genetic distance within each group and pairwise distance between transplanted smelt and H. nipponensis both ranged from 0.1% to 0.3%, and were rather smaller than those genetic distances between transplanted smelt and other species of Hypomesus (all more than 10%). The topology of each final trees further revealed that all individuals of transplanted smelt and H. nipponensis formed a strong monophyletic group. Taken together, these results all showed that the transplanted smelt were Japanese smelt H. nipponensis. In addition, even the genetic differentiation in transplanted smelt populations was not significant (P=0.06647>0.05), six populations of transplant Japanese smelt endured somewhat selection pressure of environment based on Tajima's D value. Median-joining haplotype network for Hypomesus 7 transplant populations can not tell us too much about their genetic relation and the transplant routes. Cross-transplant or/and multi-transplant might be the reason.

    • Sequences analysis of jlFABP3s and the correlation between polymorphisms and body weight gain in Carpio cyprino var. jian

      2012, 36(12):1809-1818. DOI: DOI:10.3724/SP.J.1231.2012.27971

      Abstract (2327) HTML (0) PDF 730.90 K (2447) Comment (0) Favorites

      Abstract:Fatty Acid Binding Proteins are mainly involved in fatty acid transfer in the extracellular and intracellular membrane, and also take part in the regulation of cell growth and proliferation. In this experiment, two heart and muscle fatty acid binding protein genes,jlFABP3a and 3b, were isolated from Cyprinus carpio var. jian. Consistent with other FABP3s, jlFABP3s contain four exons and three introns. The open reading frames of 3a and 3b encode 133 amino acids share 93% and 94% similarity with each other in DNA and protein level, respectively. And there was clear difference in sequences and lengths between two genes introns. Twenty-six and twenty-five SNPs were found on jlFABP3a and 3b respectively in Cryprinus carpio var. jian population using alignment sequences from different individuals. And genotypes in 3 SNP loci were detected using PCR-RFLP. The SNP-weight gain correlation analysis indicated C30G was significantly associated with male juvenile, female juvenile and adult fish weight gain (P<0.05) in total experimental samples. Individuals with CC genotype grew faster than CG individuals. G267T was significantly related with female adult fish weight gain (P<0.05) in 5 families, and three genotype individuals had same growth trends in the 7 populations, though no significant (P>0.05). Taking two SNPs (G267T and C30G) into account, correlation analysis revealed individuals with GGCC grew the fastest in female and male fish, and grew 17% and 12% faster than GGCG ones. In the experimental samples,the GGCC individuals occupy only about 9%, indicating the presence of large selection space, and can be used as reference in molecular assistant breeding of Cryprinus carpio var. jian.

    • Spatial-temporal trends of Cadmium in oyster along Guangdong coastal waters from 1989 to 2010 and their risks on human health

      2012, 36(12):1910-1916. DOI: DOI:10.3724/SP.J.1231.2012.28026

      Abstract (2248) HTML (0) PDF 556.09 K (2065) Comment (0) Favorites

      Abstract:The quality of oysters is crucial to the sustainable development of coastal oysters culturing industry and human health. This paper analyzed the spatial-temporal trends of Cd content in oyster soft tissues from 17 main Guandong coastal bays/estuaries from 1989 to 2010 and assessed their health risks on groups of consumers by their dietary compositions and ages. Results of total 268 samples showed that the concentration of Cd varied between not detected (nd) and 10.80 mg/kg wet weight with average of 1.14 mg/kg wet weight; and among of which, 98.64% of the concentrations of Cd in oyster tissues did not exceed the upper levels(4mg/Kg) which established by Ministry of Agriculture, China and EPA, USA. The Pearl River estuary should be the top of Mussel Watch and environmental management considering its highest Cd content in oysters there. Although the risks of health to the younger (aged 5 to 17) was the highest, and then was to the elder (aged 60 or more) and the adults(aged 18 to 59) in sequence, the Hazard quotient (HQ) was less than 1 for oysters from Guangdong coastal waters, indicating that the oyster consuming had not exceeded the oral Reference Dose .

    • Studies on the processing of ultramicro calcium powder from goosefish(Lophius litulon) bones by enzymatic hydrolysis

      2012, 36(12):1917-1923. DOI: DOI:10.3724/SP.J.1231.2012.28053

      Abstract (2536) HTML (0) PDF 401.78 K (2679) Comment (0) Favorites

      Abstract:Calcium plays important rule in human health. Lack of calcium intake cause many kinds of disease, especially osteoporosis. Animal bone provide an important way of obtaining calcium. Fishbone is a kind of natural calcium resource, it has the merits of high absorbability and low side effects on human. Till now, most of researches on utilization of fishbone focused on the preparation of calcium tablet from seawater fish, such as haddock, using acid or alkali method. Ultrafine comminution technology is widely used in food processing to make ultrafine powder, is given more attention nowadays. The ultrafine powder has many particular characteristics, such as increasing the utilization rate of materials, improving performances and the quality of products. Absorption of ultra-micro calcium powder with rich nutrition improved with smaller average particle size. Increasing processing of goosefish (Lophius litulon) is associated with a large amount of waste fish bone and fish head, which will both cause environment pollution and resource waste as well. How to utilize this kind of calcium source efficiently is now one of the focuses in the field of fish processing. Nevertheless, no research on goosefish bone using ultrafine comminution technology was found yet. In this study, ultramicro calcium powders were prepared from goosefish bone by enzymatic hydrolysis followed by ultrafine comminution technique,and the bioavailability of the obtained bone powder was investigated as well. The results showed that the removal rate achieved 33.8% under the optimum purification conditions of goosefish bone hydrolized by 1300 U/g alkaline protease under temperature of 50℃,for 2.5 h. Particle size distribution of calcium powders by superfine comminution for 100min was narrow, and the average particle size reached the minimum of 626.9 nm. The results of animal experiments showed that the bioavailability of ultramicro calcium powders of goosefish bone was much higher, and ultramicro calcium powders by superfine comminution for 100min exhibited calcium absorption rates of 79.3%~83.5%, which is obviously higher than that of the calcium carbonate control group. Goosefish ultramicro calcium powder prepared under the optimum conditions had pure white color, good appearance quality, and no peculiar smell with calcium content of 29.5%. It was considered as a kind of safe calcium supplementation of high quality and bioavailability.

    • Microsatellite analysis of genetic diversity in 3 wild populations of Exopalaemon carinicauda

      2012, 36(12):1819-1825. DOI: DOI:10.3724/SP.J.1231.2012.27900

      Abstract (2282) HTML (0) PDF 464.67 K (2352) Comment (0) Favorites

      Abstract:Genetic diversity of 3 wild stocks,collected from Laizhuo Bay(LZ),Haizhuo Bay(HZ),Xiangshang(XS), were investigated using 12 microsatellite loci. A total of 115 alleles were detected in 12 microsatellite loci and the number of alleles ranged from 6 to 14(mean 9.5833) . The expected and observed heterozygosities in 12 loci ranging from 0.7653 to 0.8660 (mean 0.8278) and from 0.2167 to 0.7176 (mean 0.5175), respectively. The average polymorphic information content of 12 loci was 0.7051. Mean coefficient of gene differentiation for loci( Fst ) was 0.0930(0.05

    • Carbonate deposits in marine fish intestines: contribution of Marine fish cultures to carbon sink fisheries

      2012, 36(12):1924-1932. DOI: DOI:10.3724/SP.J.1231.2012.28045

      Abstract (2787) HTML (0) PDF 471.97 K (2658) Comment (0) Favorites

      Abstract:A variety of marine ecosystems play important role in the ocean biological carbon sink. More and more often, people are paying closer attention to impacts of marine fish on carbon cycle. Recent studies showed that marine fish produce and excrete various form of precipitated calcium carbonate with high magnesium content from their guts. Precipitation occurs as a by-product of the osmoregulatory requirement of teleosts to continuously drink Ca- and Mg-rich seawater. Using the Bahamian archipelago site specific fish biomass and carbonate excretion rate data, scientists estimated that marine fish produce about 1.1×1012 kg CaCO3/year as mud-grade carbonate, and it is potential sediment constituent. Marine fish contribute over 14% to total estimated global carbonate mud production. Therefore, marine fish represent a hitherto unrecognized but significant source of fine-grained carbonate sediment, and affect coastal carbon sink capacity. This directly affect connotation of carbon sink fisheries. The carbon budget of marine fish culture may influence carbon source and carbon sink. Moreover, establishing the carbon budget model and their ability to trap carbon by cultured species is needed to produce realistic estimates for carbon sink value of marine fish culture.

    • Molecular cloning and expression analysis under high temperature stress of ribosomal protein S15a gene from Porphyra haitanensis

      2012, 36(12):1826-1833. DOI: DOI:10.3724/SP.J.1231.2012.28118

      Abstract (2776) HTML (0) PDF 732.57 K (2303) Comment (0) Favorites

      Abstract:Porphyra haitanensis is an economically important marine crop in southern China. A major problem in Porphyra farming is thallus decay in response to high temperature stress. Molecular studies of temperature stress can help to resolve the issue of thallus decay. In this study, to study the molecular mechanism of high temperature tolerance in P. haitanensis, the technology of annealling control primer (ACP) was used to screen the differential expressed genes in gametophytic blades of an F4 high temperature tolerance line Z-61. By the primers combination of dT-RSL and RSL2, one differential expressed gene fragment was cloned. And the full length sequence of this gene fragment was cloned by 5’RACE technology and named as Phrps15a(acceession number JN991055.1). The Phrps15a gene with a 676bp sequences contains an open reading frame of 390bp encoding a PhRPS15a protein of 130 amino acid residues. The PhRPS15a protein which was assembled by 3 helix, 7 sheet and 8 cycle shared high amino acid sequence identity with RPS15 from other organisms (78~80%), and its molecular formula was C664H1066N188O180S7. Phylogenetic analysis showed that the evolution of PhRPS15a of animal, higher plant, green algae and P.haitanensis has unattached evolutional group, and the PhRPS15a protein of P.haitanensis has closer relation with RPS15a proteins from green alga than ones from other organisms. The results of real-time quantitative PCR indiacted that the expressed level of Phrps15a has high relation with high temperature stress. Under high temperature stress, the expression of Phrps15a gene was down-regulated significantly.

    • Preliminary study on flg22-induced defense responses in sporophytes of Saccharina japonica (Phaeophyta)

      2012, 36(12):1834-1841. DOI: DOI:10.3724/SP.J.1231.2012.27857

      Abstract (2974) HTML (0) PDF 565.97 K (2850) Comment (0) Favorites

      Abstract:Flagellin and its N terminal 22 amino acids peptide (flg22) function as an effective elicitor, which can induce defense responses in higher plants. Marine algae and higher plants share some conserved characteristics on defense response pathways. Flg22-induced defense responses were investigated in sporophytes of Saccharina japonica in this study. The results of Evans blue dye showed that cell death in the sporophytes of S. japonica was not observed within 2 to 6 h after flg22 induction, whereas large amounts of cell death were observed from 8 to 10 h. By using TdT-mediated dUTP-biotin nick and labeling (TUNEL), fragments with 3’-OH groups of nuclear DNA were observed. The number of 3’-OH increased gradually with the induction time and spread from the induction site. The concentration of H2O2 increased rapidly in flg22-induced sporophytes of S. japonica, with a peak of about 20 μM at 3 h by using Luminol-dependent fluorescence detection method. Histological observation of radical oxygen species (ROS) production, detected by using the fluorescent dye 2’,7’- dichlorofluorescein diacetate (DCFH-DA), showed that green DCF fluorescence intensity increased gradually with the induction time, reaching the highest level at 3 h, then decreased from 3 to 5 h. The histological observation showed a consistent result with that of quantitative analysis of H2O2. According to our data, flg22 is an effective elicitor which could induce defense responses in sporophytes of S. japonica.

    • Primary investigations on the photosynthesis and respiration of leaves of Sargassum thunbergii using liquid-phase oxygen measurement system

      2012, 36(12):1842-1853. DOI: DOI:10.3724/SP.J.1231.2012.28081

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      Abstract:For clarifying the physiological and ecological adaptability of leaves of Sargassum thunbergii, the photosynthesis and respiration were investigated by using liquid-phase oxygen measurement system. The major results included two aspects: 1) The differences of maximal net photosynthetic rate (Pnmax), saturation irradiance (Isat), light compensation point (Ic), initial quantum yield α, dark respiration rate (Rd), pigment content, specific leaf area and microstructure of heteromorphism leaf (broad leaf, narrow leaf, pneumathode) were analyzed to reveal the probable reason about the change of leaf shape of S. thunbergii. 2) Effects of different temperatures and different salinities stress on Pn and Rd of broad leaves of newborn branch of S. thunbergii were researched. The preliminary analysis of the newborn branch about resistance physiology could provide reference for the artificial cultivation of S. thunbergii based on vegetative reproduction. The results were shown as follows: The optimum temperature for growth of newborn branch is 15-24 ℃ under the experimental condition in this paper. Pn had significant reduction when temperature was 5 ℃ or higher than 30 ℃ and Rd was significantly affected by low temperature (10 ℃ or below) or high temperature (higher than 30 ℃) stress for one hour treatment. However, Pn or Rd of low temperature stress groups could nearly recover to normal level after 24 h under standard culture condition. Short-term high or low salinity tests, especially salinity 0 and salinity 60 stress, had significant influence on Pn of broad leaves. However, Pn of salinity 0 group could recover to normal level after a 24 h recovery period, but Pn could not recover after exposure to salinity 60 for 9 h. During the whole stress process, Rd of salinity 40 and salinity 50 treatments both showed high value. And salinity 0 and salinity 60 stress both had significant influence on Rd. However, Rd could recover to normal level after a 24 h recovery period after exposure to different salinities for 9 h.

    • The new variety of Fenneropenaeus chinensis “Huanghai No.2”

      2012, 36(12):1854-1862. DOI: DOI:10.3724/SP.J.1231.2012.28183

      Abstract (3122) HTML (0) PDF 340.08 K (2463) Comment (0) Favorites

      Abstract:Two cultured populations of “Huanghai No. 1” variety and “Jikang 98” strain and four wild populations (the south coast of the Korean Peninsula population, Rushan Bay population, Qingdao coast population and Haizhou Bay population ) of F. chinensis were selected as base population via unbalanced nested breeding design in 2005. The multi-traits composite selection method was designed and applied for shrimp F.chinensis genetic breeding program, and three goal traits for growth rate, survival time and survivorship in resistance to White Spot Syndrome Virus (WSSV) were estimated. In order to efficiently decrease the influence of environmental differences on genetic variance, the larvae were breeded by standardised process during the constructing of the families. All pedigreed shrimps were fluorescence-tagged when they reached a body length of 3 cm. These shrimps were tagged with a unique family code by injecting different colors of “Visible Implant Fluorescent Elastomers” (VIE) before being stocked in one grow-out pond. The same number of marked shrimps were chosen from every family and randomly divided into two groups. The group cultured in the same pond was used to estimate the growth rate and survival rate, and the other group cultured in closed cement pit was infected WSSV artificially, which was used to test survivorship in resistance to WSSV later. The estimated results of genetic parameters also show that, the heritabilities of the shrimps were 0.22 for body weight at 170d, 0.14 for survivorship in resistance to WSSV, 0.03 for survival time. According to the information obtained from estimating the breeding value of individuals using BLUP method and the method of percentage weight, the group was selected on an index weighted 80% for growth rate, 15% for WSSV resistance and 5% for survival rate. In addition the breeding values (BV) were standardized, and then aggregate selection index was obtained. The next generation of families was selected to produce based on Selection index values. According to the information of Pedigree, the best mating arrangement was designed and increasing numbers of inbreeding coefficient was lower than 0.01. After four generations of selection, statistical results show that, the genetic gains of each generation on average were 13.56% for growth rate, 6.76% for disease-resistant and 5.05% for survival rate. It was revealed that the heritability of body weight was highest and with the maximal weight, in addition, the genetic gain of each generation was steadily above 12%. However, the heritability of survivorship in resistance to WSSV and survival rate were lower relatively,and the genetic gain of each generation was less and unstable. As the first F.chinensis new variety with multi-traits (better growth performance, higher survival rate and longer survival time after WSSV infection) for extensively farming in China, “Huanghai No.2” was approved by China National Aquaculture Variety Approval Committee as a new variety for aquaculture in 2009. In order to produce new disease-resistance shrimp variety, solve the viral disease of shrimp farming, it was necessary to find out the genetic mechanism of disease-resistant and improve the selection intensity of resistance-disease.

    • Effects of temporal and environmental factors on the fishing ground of Antarctic krill (Euphausia superba) in the northern Antarctic Peninsula based on generalized additive model

      2012, 36(12):1863-1871. DOI: DOI:10.3724/SP.J.1231.2012.27709

      Abstract (2461) HTML (0) PDF 549.16 K (2662) Comment (0) Favorites

      Abstract:The present study analyzed the spatial-temporal distribution of abundance for Antarctic krill (Euphausia superba) resource in the subareas 48.1, 48.2 and 48.3 from 1998 to 2009 using the generalized additive model (GAM) based on the data derived from Statistical Bulletin (Volume 23) of Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the relationship between standardized catch per unit fishing effort (CPUE) of Antarctic krill fishery and environmental factors (sea surface temperature (SST) and chlorophyll a) are also be analyzed. The results showed that the cumulation of deviance explained (%) of model to CPUE is 51.11, 69.25 and 65.82 respectively and the variation that provide the maximum contribution is month for 3 subareas. Standardized annual average CPUE was stable in the 3 subareas during 1998 – 2009. The inter-annual variation on average CPUE in the subarea 48.1 was smallest and that of subarea 48.3 was larger than subarea 48.2. Annual variation on average CPUE had no significant difference among 3 subareas, within the subarea 48.2 and the subarea 48.3, however, remarkably difference can be found on annual average CPUE in the subarea 48.1. The monthly average CPUE only had present the unimodal distribution in the 3 subareas, the peak value of CPUE in the subareas 48.1, 48.2 and 48.3 occurred in April, May and June respectively. The monthly average CPUE had no significant difference among 3 subareas, however, remarkably difference can be found on monthly average CPUE within 3 subareas. The suitable range of SST is -3 to 2 ℃ in the subarea 48.1, -2 to 2 ℃ in the subarea 48.2, 0 to 5 ℃ in the subarea 48.3 respectively for Antarctic krill fishing ground and the dominant CPUE values ranged in the SST of -2 to 1℃ in the subarea 48.1, -1 to 0 ℃ in the subarea 48.2, 0.8 to 2.4 ℃ in the subarea 48.3 respectively. The dominant proportion of CPUE values were in the range of 0 to 0.2 mg?m-3 for chlorophyll a concentration in the subarea 48.1 (53%), 48.2 (39%) and 48.3 (51%).

    • The study of deposition and degradation of astaxanthin in rainbow trout (Oncorhynchus mykiss)

      2012, 36(12):1872-1879. DOI: DOI:10.3724/SP.J.1231.2012.28010

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      Abstract:In the present study, four treatments with triplicates were designed with colored or un-colored rainbow trouts with average initial weight of (101.9±1.3)g. Un-colored rainbow trout was fed with diet containing 100mg/kg astaxanthin to study the deposition of astaxanthin in body (astaxanthin deposition group). Colored rainbow trout was fed with basal diet with 100mg/kg astaxanthin addition (positive control) or without astaxanthin addition (feeding degradation group), or deprived of diet during the whole feeding period (starving degradation group) to study the degradation of astaxanthin in body. The feeding trial last for four weeks. Samples, including muscle, liver and serum, were collected once a week, and measured with astaxanthin contents of flesh, liver and whole fish, serum carotenoids, flesh chromatism(L*, a*, b*), and flesh Salmo Fan score. Results showed that in astaxanthin deposition group, astaxanthin contents of flesh and liver, flesh a* value, Salmo Fan score of rainbow trout increased with feeding time prolonging (P<0.05), and kept stable in the 3rd week. There were no significant difference in these indexes between 3rd week and 4th week(P>0.05). In the whole feeding period, astaxanthin content of whole fish tended rise, but axtaxanthin retention rate of whole fish tended to decrease. In the first week and in the fourth week, astaxanthin content and axtaxanthin retention rate of whole fish were 3.71 mg/kg, 8.59 mg/kg and 21.31% 15.26%, respectively. In both starving and feeding degradation groups, astaxanthin content of tissue, flesh a* and Salmo Fan score of rainbow trouts decreased with feeding time prolonging(P<0.05), but the decreasing trend of these indexes slowed down in the 3rd week. The decreasing speed of these indexes in starving degradation group was faster than those in feeding degradation group.. Results above showed that an addition of 100mg/kg astaxanthin in diet could make the flesh of rainbow trout present ideal red colour after three weeks feeding, but astaxanthin retention rate decreased with feeding time prolonging. For rainbow trout fed diet without astaxanthin or deprived of diet, flesh astaxanthin and a* value significantly decreased during feeding period, and starving make astaxanthin reduce more quickly than feeding diet without axtaxanthin. The degradation speed of astaxanthin in body of rainbow trout tended to slow down with time prolonging.

    • Effects of carbon source and C/N ratio on treatment of aquaculture wastewater by denitrification

      2012, 36(12):1880-1890. DOI: DOI:10.3724/SP.J.1231.2012.28032

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      Abstract:To address the problem of insufficient carbon source in the treatment of aquaculture wastewater by denitrification, this study tested the effects of six carbon sources and different C/N ratio, using the removal rate of ammonium nitrogen and accumulation rate of nitrite as indicators. The results showed that carbon sources and C/N ratio did not significantly impact the removal rate of ammonium nitrogen, which was up to 98% in the treatment groups, significantly higher than that in the control group (p<0.05). When glucose and glycerol were used as the carbon sources, there was clear nitrite accumulation. When alcohols was used as the carbon source, the accumulation of nitrite was almost zero, whereas the removal rate of nitrate was up to 90%, significantly higher than that in the control group (59%). When ethanol was used as the carbon source and C/N ratio was 3.0, the removal rate of total nitrogen, ammonia nitrogen and nitrate were especially high, up to 93.28%, 98.90% and 91.82%, respectively. Although the extra carbon could substantially increase the concentration of CODMn, but it maybe rapidly degraded by denitrifing bacteria within a short time. In addition, the extra carbon could improve the stability of pH value of aquaculture wastewater to be between 7.2~7.8. The results of the present study suggest that the extra carbon source could significantly improve water quality and biological nitrogen removal efficiency during wastewater purification process in recirculating aquaculture systems.

    • Molecular characteristics and antimicrobial sensitivity of bacterial pathogen from the outbreak of Litopenaeus vannamei red-body disease

      2012, 36(12):1891-1900. DOI: DOI:10.3724/SP.J.1231.2012.28098

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      Abstract:Red-body disease is one of the most severe diseases of Litopenaeus vannamei. An outbreak of Litopenaeus vannamei red-body disease happened in a large-scale breeding farm in Zhejiang Province, 2011, with the mortality rate of >90%. A total of ten bacterial isolates were collected from the hepatopancreas of diseased shrimps, which were responsible for this outbreak. These isolates were identified as Vibrio parahaemolyticus by Vitek and 16S rRNA sequence analysis. Multilocus sequence typing (MLST) based on the concatenated genes dnaE-gyrB-recA-dtdS-pntA-pyrC-tnaA demonstrated that these isolates belonged to three novel sequence types (ST), with one isolate to ST413, seven to ST414 and two to ST415. ST413 contained two novel allelic profiles, recA-166 and tnaA-121, and ST414 harbored one novel allelic profile, gyrB-219. These novel allelic profiles and STs had been confirmed and deposited by the MLST website (http://pubmlst.org/vparahaemolyticus/). MLST results indicated these V. parahaemolyticus isolates did not originate from the same clone and exhibited remarkable genetic diversity. On the other hand, all of these isolates contained molecular markers for pandemic group, including a unique sequence within the toxRS operon, encoding transmembrane proteins involved in the regulation of virulence-associated genes, and VPA1168 within an 16-kb insertion, which encodes a hypothetical protein with approximately 80% similarity to the Mn2 and Fe2 transporter in Vibrio vulnificus. Also these isolates had the same virulence-associated gene composition (tlh tdh-trh-T3SS1 T3SS2-) and antimicrobial sensitivity profiling. Absence of tdh and trh, which had traditionally been thought to be critical for the virulence of V. parahaemolyticus, did not lead to the reduction of bacterial pathogenicity in Litopenaeus vannamei. Overall, these V. parahaemolyticus isolates might represent distinct variants within PG.

    • Developmental stages and migratory routes of larvae eels from southeast coastal estuaries of China

      2012, 36(12):1793-1801. DOI: DOI:10.3724/SP.J.1231.2012.27972

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      Abstract:Abstract: A total of 534 larvae of Anguilla japonica were collected from 9 estuaries in Guangdong, Fujian, Zhenjiang, Shanghai and Jiangsu Province, China, during Jan. -Mar. of 2008.Their pigmentation stages were determined according to the distribution of pigments on the body surface. The age of leptocephali at metamorphosis(Tm), time between metamorphosis to arrival at the estuaries (Tt-m), and age of glass eels (Tt) arriving at the 9 sites were counted according to the number of daily growth increments in the sagitta. The mean Tm was 102 d (90 d to 112 d) and progressively increased from south to north. The homogeneity tests for Tt, Tm and Tt-m among nine estuaries were conducted by Scheffe’s multiple comparison method. According to sampling location and Tm value, leptocephali were divided into three homgeneous groups. Group I was located in two southern sampling sites (Xinhui and Shantou) and had the lowest Tm. In contrast, group III in the 3 northern sampling sites (Jiuduansha, Cixi, Dafeng) had the highest Tm. Group II were in the four mid-sites (Fuqing, Ningde, Wenzhou, Taizhou). Similar result was acquired by R-cluster dendrogram of nine sampling sites and Q-cluster dendrogram of every sample based on Tm. These results indicated that the leptocephalus might migrate in three populations along the North Equatorial Current from their spawning ground to the northeastern continental shelf waters of Philippines, to Kuroshi Current and then to the estuaries of China for metamorphose. The fast-growing leptocephali metamorphosed earlier, and migrated to the southern estuaries and then entered into Guangdong coastal rivers, while the slow-growing ones metamorphosed later and migrated to the Changjiang estuary and the northern estuaries of the range. The remaining leptocephali migrated to the middle coastal waters of East China Sea. The difference of metamorphosis age between south leptocephali (91.87?1.36 d) and north (106.00?3.22 d) was 14.13 d. If the leptocephali were drifted by the Kuroshio Current at a velocity of 96 km day-1, the dispersal distance of the leptocephali for 14.03 d would be 1350 km, approximately equal to the distance between Xinhui and Dafeng. These results suggest that glass eel of Chinese estuaries was passively transported by the Kuroshi Current from the south to north at their leptocephali stage.

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