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[Abstract](381) [FullText HTML](124) [PDF 626KB](14)
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Chinese sea bass (Lateolabrax maculatus) with initial body mass of (25.49±0.20) g were fed for eight weeks with six diets containing 0 (control), 1% (T1), 2% (T2), 3% (T3), 4% (T4) and 5% (T5) Spirulina platensis, so as to investigate the effect of S. platensis on the growth performance, digestive enzymes, haematological indices and antioxidant capacity of L. maculatus. The results show that the dietary supplementation with S. platensis improved the weight gain rate (WGR) and specific growth rate (SGR) of L. maculates (P<0.05) significantly. The feed conversion ratio (FCR) decreased significantly (P<0.05). The protease activities in S. platensis supplemented groups were significantly higher than that of the control (P<0.05), while no significant change was observed in lipase and amylase activities among different groups. Compared with the control, the levels of red blood cell (RBC) increased in T4 and T5 groups significantly (P<0.05), and levels of white blood cell (WBC) and hemoglobin (Hb) in T3, T4 and T5 groups were significantly higher than those of the control (P<0.05). The levels of triglyceride, cholesterol, low-density lipoprotein cholesterol (LDL-C) in T4 and T5 groups decreased significantly than those of the control (P<0.05). The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities in T3, T4 and T5 groups were significantly higher than those of the control (P<0.05). The malondialdehyde (MDA) contents in T3, T4 and T5 groups were significantly lower than those of the control (P<0.05). It is suggested that the suitable S. platensis supplementation level in diet of L. maculates is 4%−5%.
[Abstract](147) [FullText HTML](58) [PDF 0KB](2)
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To investigate the antibacterial substances from Bacillus amyloliquefaciens HE and antibacterial characteristics, we synthetized the genes related to lipopeptides synthesis by PCR detection according to the stability of B. amyloliquefaciens fermentation broth, and further analyzed the active substances by UPLC-Q-TOF-MS. Then we applied the inhibition zone method to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of lipopeptide against Aeromonas hydrophila, whose antimicrobial activity was discussed from the microscopic structure. The antimicrobial active substances were stable against high temperature, acid, acid-base and protease. The PCR with four primer pairs were cloned and sequenced. The BLAST analysis shows that the ituA, fenB, sfP and mycB genes existed in the genome of B. amyloliquefaciens HE. Three kinds of lipopetides (Surfactin, Iturin and Fengycin) were identified in the antimicrobial extract by mass spectrum analysis. The MIC and MBC of antimicrobial lipopetides against A. hydrophila were both 137.97 μg·mL−1 by inhibition zone method. The microscopic characteristics indicate that lipopeptides can cause membrane collapse and holes in A. hydrophila cells. The results provide references for the structural identification and safety evaluation of active metabolites of B. amyloliquefaciens.
[Abstract](368) [FullText HTML](151) [PDF 0KB](10)
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To better understand the status of fishery resource of Kaozhouyang Bay, we have conducted a seasonal investigation of the community structure and diversity of the nekton by using gill nets and cages net from November 2017 to July 2018. A total of 93 economic species were collected, and among them 61 were fish belonging to 11 orders and 33 families, accounting for 64.52% of the total species number, and the rest were crustaceans. Perciformes (45.16%) and Clupeiformes (7.52%) which were mostly warm water species were the two largest orders of fish. The catches had significant seasonal variation (summer>spring>autumn>winter), and mostly fell in two intervals of 0−8 g and 8−64 g. The diversity indices in Kaozhouyang Bay showed obvious variation. The species richness index was 0.81−3.63; the Shannon-Wiener index was 0.81−2.03; the evenness index was 0.55−1.69. No significant difference was found in the richness index, Shannon-Wiener index and evenness index among different seasons and stations. In conclusion, the total fishery resources in Kaozhouyang Bay are relatively small. The biodiversity shows obvious seasonal variation, while the spatial variation is in significant.
[Abstract](360) [FullText HTML](137) [PDF 0KB](4)
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We observed and determined the sagittal otoliths morphology of 105 individuals of genus Decapterus (Decapterus macrosoma, D. tabl and D. kurroides) collected from the Dongsha Islands in the South China Sea. The sagittal otolith shape of the genus Decapterus was long oval with developed rostrum, and the difference between species was distinct. The front end of D. macrosoma rostrum was slightly bent downward. The knob of otolith dorsal of D. tabl was obviously developed with serrated shape, and the front end of rostrum was slightly broad and thick. The overall outline of D. kurroides otolith was smoother, and antirostrum was poorly developed. According to the morphological indices (otolith length, otolith width, rostrum length, rostrum width, otolith mass and otolith area), the classification of different species of the genus Decapterus (D. macrosoma, D. tabl and D. kurroides) achieved success rates of 100%, 100% and 91.7%, respectively. It is shown that sagittal otolith can identify genus Decapterus.
[Abstract](390) [FullText HTML](107) [PDF 0KB](1)
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We analyzed the resource dynamic, diversity and community structure of nekton based on the data collected by demersal trawl at Daya Bay mouth in 2015. The results show that the density of nekton in summer was significantly higher than that in the other seasons (F=4.556, P=0.01), and it was mainly affected by the seasonal alternation of nekton dominants. The first dominant species in each season were Paerargyrops edita (in spring), Thamnaconus hypargyreus (in summer), Leiognathus brevirostris (in autumn) and Portunus gladiator (in winter), respectively. The Shannon-Wiener diversity index of nekton community varied between 2.35 and 2.66, and the seasonal difference was not significant (F=0.597, P=0.623). However, the cluster and non-measured multi-dimensional scale sequencing (NMDS) analyses show that the dissimilarity of nekton community in different seasons varied from 69.13% to 80.77%. Therefore, the single α diversity index can not reflect the characteristics of the nekton community of the survey area effectively. The results of redundancy analysis (RDA) indicate that there is clear relationship between seasonal heterogeneity of nekton community and environmental factors such as water temperature, dissolved oxygen, salinity, transparency, pH and chlorophyll a.
[Abstract](510) [FullText HTML](205) [PDF 0KB](17)
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To study the role of TGF-β/Smad signaling pathway in zebrafish (Danio rerio) ovary under different photoperiod conditions, we detected the relative expression of relevant genes in TGF-β/Smad signaling pathway of zebrafish ovary under continuous dark (0 L∶24 D, DD), natural photoperiod (14 L∶10 D, LD) and continuous light (24 L∶0 D, LL) using quantitative real-time PCR. The location of p-Smad2 in zebrafish ovary was detected by immunohistochemical technology. The results show that the expression patterns of genes involved in TGF-β/Smad signaling pathway were different in zebrafish ovary under different photoperiod conditions, and the expression profiles of ligand (tgfb3), receptor (tgfbr2a, tgfbr2b and tgfbr1b) and downstream protein kinase (smad2 and smad3a) were consistent. The relative expression levels of the above six genes were the highest in DD group and the lowest in LL group after 3-day treatment of different photoperiods, and an opposite trend was observed after 7 d. The p-Smad2 protein signal was detected in the development of zebrafish oocytes from previtellogenic stage (PV) to full-grown immature stage (FG). Photoperiod treatment did not affect the localization of p-Samd2 in zebrafish ovary. The results suggest that change of photoperiod might affect the ovarian development of zebrafish by changing the expression pattern of genes of tgfb3/receptor/protein kinase.
[Abstract](588) [FullText HTML](183) [PDF 0KB](15)
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The elongases of very long chain fatty acids (Elovls), which are key rate-limiting enzymes in the long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis pathway, can extend the carbon chain of PUFAs. To investigate the function of Elovl4 in PUFA biosynthesis of Trachinotus ovatus, we cloned its cDNA sequence (ToElovl4-like), whose open reading frame (ORF) was 792 bp, encoding 263 amino acids. Bioinformatics analysis reveals that the encoded amino acids contained significant structural features of Elovl family such as histidine cassettes, multiple transmembrane regions and ER retention signals. The results of sequence alignment show that Elovl4-like gene was highly conserved, and the similarity between the protein sequence encoded by this gene and other fish was 73%−86%, among which Gadus morhua had the highest similarity of 86%. Phylogenetic analysis shows that Elovl4 mainly clustered into three categories (Elovl4a, Elovl4b and Elovl4-like). Among them, ToElovl4-like was closely related with Elovl4-like of other fish. Real-time PCR shows that ToElovl4-like gene was expressed in all tissues, with the highest mRNA expression in gonads and spleens and the lowest in brain. The heterologous expression of yeast shows that ToElovl4-like could extend 18:2n-6 and 20:5n-3 to 20:2n-6 and 22:5n-3, respectively. The above studies provide a theoretical basis for understanding the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA).
[Abstract](507) [FullText HTML](183) [PDF 935KB](8)
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A sensitive and reliable ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was eatablished for the determination of olaquindox (OLA), carbadox (CBX), cyadox (CYA), quinocetone (QCT), mequindox (MEQ) and their main metabolites (QCA and MQCA) in fishmeal. The samples were extracted by acetonitrile-ethyl acetate mixture (1∶1, V/V) and hydrochloric acid solution (1 mol·L–1), then the analyte which dissolved in the aqueous phase was re-extracted by ethyl acetate. The extraction was concentrated and reconstituted with acetonitrile. After purification with the Oasis PRiME HLB SPE cartridge, the sample was subjected to the following analytical procedure. The mobile phase containing acetonitrile and 0.1% formic acid solution with a linear gradient elution was utilized to separate all compounds on a Phenomenex Kinetex C18 column. The quantitative analysis of metabolites was carried out with an internal standard method and the others with an external standard method in the multiple reaction monitoring mode using positive electrospray ionization. The calibration curves for all compounds were linear (r≥0.994) within their corresponding concentration range. The recoveries were 64.4%−102.2% at different spiking levels with RSDs of 3.2%−10.2%. The limits of detection and quantification of MQCA and QCA were 2 μg·kg–1and 5 μg·kg–1; MEQ was 10 μg·kg–1 and 20 μg·kg–1; the others were 1 μg·kg–1 and 2 μg·kg–1, respectively. This method with high sensitivity and good precision can be applied to the simultaneous determination of quinoxaline drugs and their major metabolite in fishmeal samples.
[Abstract](383) [FullText HTML](148) [PDF 1878KB](7)
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During the pneumatic conveying process of automatic feeding systems for deep-water off-shore cage culture, blockages of pipeline and damage to feed pellets occur easily. To reveal the pneumatic transport characteristics of pellet feed in automatic feeding system, a numerical simulation of gas-solid two-phase flow of feed pellets in a pipeline was carried out. Based on gas-solid two-phase flow theory, both a computational fluid dynamics (CFD) model and discrete element model were established. The movement process of feed particles from the initial stage to the stable stage of pneumatic conveying pipeline was analyzed, and the position distribution of feed particles from the initial stage to the stable stage was obtained. Pressures at various locations in the pipeline were analyzed and compared to determine the pressure drop between the pipeline inlet and the instant at which the flow reached the steady state. The results provide references for the simulation and optimization design of automatic baiting equipment, which can better guide the movement of feed particles and reduce the collision energy loss of particles at elbow.
[Abstract](1244) [FullText HTML](1141) [PDF 833KB](5)
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We analyzed 15 persistent organic pollutants (POPs) residues such as organochlorine pesticides and polychlorinated biphenyls in cultured shellfish (Mactra veneriformis, Ruditapes decussatus and Ostrea gigas, etc.) in Shandong coastal areas by gas chromatography (GC), comparing with the data at home and abroad, and investigated their residual level, spatial distribution and seasonal distribution characteristics. The risk assessment was evaluated by EPA method. The results show that w(HCHs), w(DDTs) and w(PCBs) were n.d.-17.6 μg·kg–1, 2.68-66.7 μg·kg–1 and n.d.-36.8 μg·kg–1 (wet mass, the same below). HCHs residues accorded with the first-class biological quality evaluation standard in Marine Biological Quality. Besides, 73% of samples had DDTs between the first and the second standards. OCPs and PCBs residues in all samples did not exceed the standard limits in National Food Safety Standard-Maximum Residue Limits for Pesticides in Food, Contaminant Limits in. There were no exposure risks and cancer risks were at acceptable level. Compared with the shellfish in other coastal waters, the residues of HCHs, DDTs and PCBs in the shellfish in Shandong coastal waters are at medium level.
[Abstract](490) [FullText HTML](179) [PDF 826KB](22)
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We investigated the anaesthetic effect of eugenol at different mass concentrations on juvenile Siganus oramin with body mass of (4.83±1.30) g at natural seawater at temperature of (29.3±1.1) ℃. The results show that when the mass concentration of eugenol was 30−80 mg·L–1, the anesthesia time reduced but the recovery time increased with the increase of mass concentration of eugenol. During the anesthesia, the respiratory rate of juvenile S. oramin increased at light anesthesia state, but decreased rapidly during deep anesthesia until the respiratory arrested due to excessive anesthesia. When the mass concentration of eugenol was 30−100 mg·L–1, the juvenile S. oramin could reach Stage 4 anesthesia within 3 min and recovered less than 4 min with a survival rate of 100%. When the air exposure time was within 8 min, the recovery time slightly reduced with extension of air exposure time; when the air exposure time was longer than 8 min, the recovery time increased but the recovery rate decreased with the extension of air exposure time. It is indicated that eugenol with advantages of fast anesthesia, short recovery time and high recovery rate, is an ideal anesthetic for juvenile S. oramin. The concentration of eugenol is suggested to be 30 mg·L–1 in production, and the artificial operation time should not exceed 6 min after anesthesia. The anesthesia concentration should not exceed 80 mg·L–1 even for faster anesthesia.
[Abstract](412) [FullText HTML](152) [PDF 633KB](6)
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A total of 58 180 microsatellites were developed by RAD-Seq high-throughput sequencing technology in Decapterus macrosoma. One hundred and twelve microsatellite loci were randomly selected from di-/tri-nucleotide repeat microsatellite loci. Finally, twenty-seven highly polymorphic markers were developed. The population genetic analysis finds 18 dinucleotide-repeated microsatellite loci (9−14 repeated) and 9 trinucleotide-repeated microsatellite loci (6−10 repeated). The number of alleles (Na) ranged from 5 to 17 (mean 10.6). The observed and expected heterozygosities ranged from 0.342 9 to 0.857 1 (mean 0.631 7) and 0.538 3 to 0.911 8 (mean 0.796 8), respectively. The polymorphism information content (PIC) ranged from 0.497 to 0.886 (mean 0.780 9), and the PIC at all loci except for one was geater than 0.500, indicating that the microsatellites were highly polymorphic. The Hardy-Weinberg equilibrium test (HWE) shows that 19 microsatellite markers conformed to HWE. There is no linkage imbalance among 27 loci. The 27 microsatellites developed by this study will be useful for further population genetic analysis.
[Abstract](410) [FullText HTML](136) [PDF 674KB](5)
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In this paper, the effects of ammonia-N (NH4-N) stress on the activities of lysozgme and three digestive enzymes of Babylonia areolata were studied to reveal the physiological changes. The results show that both the concentration and treatment time of NH4-N had a significant effect on the activities of digestive enzymes of B. areolata (P<0.05). Compared with the control group: 1) As the treatment time of NH4-N increased, the lysozyme generally demonstrated a suppression-induction trend. 2) The lower concentration of NH4-N (22 mg·L–1) showed an induction- suppression trend to the pepsin activity, while the other concentrations generally showed a suppression-induction trend. 3) The lipase activity of B. areolata was generally suppressed or similar with that of the control group with the prolongation of treatment time. 4) The NH4-N treatment time affected the amylase activity significantly, but in the case of short treatment time the lysozgme activities of treatment groups did not have much induction or suppression. In conclusion, the stress of ammonia-N can influence the activities of these four digestive enzymes of B. areolata.
[Abstract](484) [FullText HTML](151) [PDF 1286KB](13)
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We observed and drawn the external morphology 131 Thamnaconus septentrionalis collected from the Yellow Sea, and counted the number of dorsal fin rays, caudal fin rays, anal fin rays as well as pectoral fin rays, so as to conduct a regrassion analysis of their morphological features. Besides, the chromosome specimens were made by hot titration method, and the karyotype was analyzed. The results are: 1) when alive, the head and back of T. septentrionalis′ body were in pewter and the abdomen was in whitish turquoise; after death, the color turned dark green. The fins′ remaining turquoise was an obvious feature of its external morphology. 2) The body length was 1.5−3.3 times and 3.1−4.9 times as long as the body height and the head length; the head length was 1.1−1.6 times as long as the proboscis length. 3) The variation of total length/standard length was minimum with the smallest difference between female and male and had the best correlation coefficient (R2=0.96). The values of caudal length/caudal depth, standard length/caudal length, head length/eye diameter and head length/eye interal had the lowest correlation coefficient, and the difference between female and male was obvious. 4) The fin type was: dorsal fin II, 36−39; anal fin 34−37; tail fin 14−15, caudal fin 1+10+1, and the pelvic fin degenerated into pelvic fin spines. 5) The body was covered with a variety of fleece scales consisting of a base plate and a bony bulge, and the lateral lines were composed of trunk line and infraorbital line. 6) T. septentrionalis had 20 pairs of chromosomes (2n=40) and the karyotype formula was 2n=40t. All of them were telomeres without heteromorphic sex chromosomes.
[Abstract](495) [FullText HTML](178) [PDF 1745KB](8)
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Pellino protein is a member of highly conserved E3 ubiquitin ligase which plays an important role in ubiquitination and innate immunity. In this study, we cloned and identiﬁed a crustacean Pellino from Penaeus monodon (PmPellino). The full-length cDNA of PmPellino consisted of 1 961 bp with an 89 bp 5'UTR, a 573 bp 3'UTR and a 1 299 bp open reading frame encoding 432 amino acids. PmPellino mRNA was detected in all the tissues examined by real time PCR (highest in gill). The expression of PmPellino in hepatopancreas was significantly up-regulated after acute ammonia nitrogen stress (P<0.01), but it was inhibited in gill (P<0.01). Vibrio harveyi could significantly activate the expression of PmPellino in gill and inhibit its expression in hepatopancreas. V. anguillarum could significantly inhibit the expression of PmPellino in hepatopancreas, but there was no sigficant difference in gill with the control group. Staphylococcus aureus could significantly activate the expression of PmPellino in both hepatopancreas and gill. The results indicate that PmPellino might play an important role in the immunity of P. monodon.
[Abstract](595) [FullText HTML](233) [PDF 791KB](19)
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In order to study the rationality of the release of the Portunus trituberculatus in Zhoushan fishing ground, Yangtze River estuary fishing ground and their adjacent waters in recent years, we analyzed the energy flow characteristics of the ecosystem in that sea area and estimated the proliferation capacity ofP. trituberculatus based on the fishery resources survey data from 2006 to 2014 by constructing the Ecopath model. The results show that the ecosystem was mainly made up by benthos, and shrimps, Trichiurus leptures andP. trituberculatus had higher food utilization rates. The food utilization rates ofChelidonichthys kumu and Trachurus japonicuswere relatively low. Four trophic levels can be divided in the survey area, and P. trituberculatus is a medium trophic organism. The total catch was 1.614 t·km–2 (the catch of P. trituberculatus was 0.057 8 t·km–2). The total consumption was 280.744 t·km–2. The total export was 790.396 t·km–2. The total production was 959.3 t·km–2. The biomass of P. trituberculatus was 0.125 t·km–2. The ecological capacity was 1.125 t·km–2. The proliferation capacity was 1 t·km–2. It is shown that the primary productivity of the survey area is high, and the marine organisms are distributed in the second and third trophic scales with relatively low ecosystem maturity. There is still a certain releasing space.
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2019, 15(2).
[Abstract](229) [PDF 1498KB](7)
Abstract:
2019, 15(2): 1-11.   doi: 10.12131/20180197
[Abstract](644) [FullText HTML](243) [PDF 975KB](23)
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In order to investigate the size selectivity of codend of shrimp beam trawl for Metapenaeus ensis, with covered codend method and trouser trawl method, we carried out fishing experiments on two traditional diamond-mesh codends (D25 and D30), and six novel combined square-mesh and diamond-mesh codends (S35+D18, S25+D25, S30+D25, S35+D25, S35+D30 and S35+D35) in the South China Sea during 2014−2017. We used maximum likelihood method to estimate the selective parameters at haul by haul level and combined haul level with the logistic equation. The results indicate that the D25 and D30 codend were nearly nonselective for M. ensis. In experiments of covered codend method, the mean 50% retention lengths (L50) of M. ensis for the S35+D18, S25+D25, S30+D25 and S35+D25 codends were 51.52 mm, 60.84 mm, 63.21 mm and 64.53 mm, respectively, and the mean selection ranges (SR) were 16.48 mm, 14.31 mm, 12.84 mm and 9.75 mm, respectively. In the experiments of trouser trawl method, the mean L50s for the S35+D25, S35+D30 and S35+D35 were 75.43 mm, 82.38 mm and 95.39 mm, respectively, and the mean SRs were 6.93 mm, 6.39 mm and 20.44 mm, respectively, and the mean relative fishing intensities (p) were 0.51, 0.52 and 0.64, respectively. Considering the first mature length of M. ensis (80 mm) in the South China Sea as well as economical efficiency of fishing and selective properties of codends, it is suggested that the S35+D30 has the best selectivity. The results are benefit for the management of shrimp beam trawl and sustainable harvest of the fishery resources of M. ensis in the South China Sea.
2019, 15(2): 12-19.   doi: 10.12131/20180143
[Abstract](850) [FullText HTML](254) [PDF 6464KB](17)
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In order to assess the effects of the construction of Zhenlin Bay marine ranching in the eastern Guangdong, we compared the variation in sea surface temperature (SST), chlorophyll a concentration (Chl a), catch per unit effort (CPUE), biodiversity, biomass and density of zoobenthos during the pre- (August, 2011) and post- (August, 2013) marine ranching in Zhelin Bay, based on satellite remote sensing and survey data. Results show that the N/P ratio was nearly 16, and Chl a increased from 7.5–12.3 mg·m–3 to 10.4–16.2 mg·m–3. CPUE increased from 2.1–5.5 kg·h–1 to 5.8–14.5 kg·h–1. The species number of fish, crustaceans, cephalopods and shellfish increased by 25, 3, 2 and 3, respectively. The Shannon-Wiener biodiversity index of fish, crustaceans, cephalopods and shellfish increased by 0.5, 0.4, 0.1 and 1.0, respectively. Both biomass and density of zoobenthos also increased. The construction of marine ranching in Zhelin Bay has restored the habitat to some extent, and played a positive role in the conservation and proliferation of fishery resources.
2019, 15(2): 20-28.   doi: 10.12131/20180149
[Abstract](720) [FullText HTML](243) [PDF 1218KB](12)
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Based on the data of marine fishing production structure in the South China Sea during 2015−2017, we investigated the effect of summer fishing moratorium by studying the indicators such as daily yield, daily output value, catch per unit effort (CPUE) and trawl fishing rate before and after summer fishing moratorium, with differential test and growth rate analysis. Compared with the data before the moratorium, the daily yields of fishing boats after summer fishing moratorium increased by 19.21%, 49.99% and 114.64% in 2015, 2016 and 2017, respectively; the average daily output values increased by 0.40%, 16.06% and 49.14%, respectively; CPUE increased by 7.12%, 73.30% and 110.90%, respectively. The fishing moratorium system had a significant impact on the daily output of fishing vessels (P<0.05), but a limited impact on the daily output value, CPUE, catch rate and fishing structure (P>0.05). To sum up, summer fishing moratorium in the South China Sea affects the yield increment significantly, but affects the resource community structure not so much. The effect in 2017 is better than that in 2015 and 2016.
2019, 15(2): 29-37.   doi: 10.12131/20180178
[Abstract](779) [FullText HTML](276) [PDF 1069KB](5)
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In order to study whether aeration will promote the occurrence of cyanobacterial (Microcystis spp.) blooms in aquaculture ponds, we conducted an experiment (a treatment group and a control group) in a greenhouse during summer, without sediment addition and three replicates of glass tanks. The control group was not aerated, but the treatment group was aerated with common aeration intensity for aquaculture ponds. Inorganic nitrogen and phosphorus nutrients were added to both the control and the treatment groups twice. The initial phytoplankton was dominated by green algae, then Microcystis gradually appeared in both two groups, and then became the most dominant species at later stage of the experiment (average wet mass of 36.28−75.81 mg·L–1). The dissolved oxygen mass concentration in the control was significantly higher than that in the treatment (P<0.05); however, there was no significant difference between both groups (P>0.05), including chlorophyll a, total algal wet mass, cyanobacteria wet mass, green algae wet mass, proportion of Microcystis to the total wet mass, as well as zooplankton contents. It is indicated that aeration disturbance in aquaculture ponds has no direct influence on the occurrence of Microcystis dominance, which can appear either at the presence or absence of aeration disturbance, and the aeration disturbance mainly changes the position of Microcystis colonies in the water column.
2019, 15(2): 38-46.   doi: 10.12131/20180193
[Abstract](1198) [FullText HTML](332) [PDF 1068KB](15)
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In order to explore the regulation rule of spermatozoa motility of Schizothorax irregularis, and to improve its fertilization rate and fingerling production efficiency, we applied a significance test and response surface method to study the single regulation and compound regulation of glucose, glycerol and three salts on sperm motility of S. irregularis. The results show that the maximum fast movement time of S. irregularis spermatozoa was 37.00 s when glucose was 433.7 kPa, significantly higher than those in the other groups (P<0.05). The maximum fast movement time of S. irregularis spermatozoa was 32.33 s when glycerol was 506.7 kPa, without difference with that in 416.3 kPa group, but was significantly higher than those in the other groups (P<0.05). The maximum fast movement time of S. irregularis spermatozoa was 35.00 s when sodium chloride was 431.4 kPa, without difference with that in 348.8 kPa group, but was significantly higher than those in the other groups (P<0.05). Potassium chloride had no obvious effect on activating spermatozoa, and magnesium chloride solution showed inhibition effect for spermatozoa. An equation about the relation of fast movement time and glucose, glycerol and sodium chloride was established. The linear and quadratic effects of the equation were very significant (P<0.01), and interaction effect was significant (P<0.05). The optimizied formulation of model was sodium chloride of 164.78 kPa, glycerol of 216.55 kPa, glucose of 208.43 kPa, and the theoretical FT was 68.24 s. The results indicate that the optimized activator formula by response surface methodology can improve the motility of S. irregularis spermatozoa.
2019, 15(2): 47-57.   doi: 10.12131/20180185
[Abstract](715) [FullText HTML](297) [PDF 13651KB](18)
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We isolated 14, 4 and 2 strains of Streptococcus agalactiae from naturally infected adult and juvenile tilapia as well as tilapia naturally carrying S. agalactiae, respectively. The clinical signs and anatomy changes of adult tilapia were as follows: erratic swimming, congestion of brain, eyeballs, gills and fins, exophthalmia, corneal opacity and swelling of visceral organs, which were characterized by histopathological changes with tubular hyaline degeneration, meningitis and epicarditis. The clinical symptoms of juvenile tilapia were not obvious, but some of the internal organs showed swelling and congestion, characterized by main histopathological features of hemorrhage of spleen vascular area, degenerated renal tubular epithelial cells and milder inflammatory response in brain tissue. In addition, eosinophil infiltration was found in the lamina propria of tilapia and in the liver of juvenile fish. It was observed that S. agalactiae proliferated in the brain and heart of adult fish and in the liver of juvenile tilapia, respectively. The clinical symptoms and histological lesions in tilapia carrying S. agalactiae were not obvious. The results of PCR detection show that all the S. agalactiae strains had the same virulence gene profiles, but there were significant differences in pathological damages among adult fish, juvenile fish and tilapia carrying S. agalactiae.
2019, 15(2): 58-63.   doi: 10.12131/20180194
[Abstract](879) [FullText HTML](495) [PDF 691KB](18)
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Fish anesthetic eugenol, which has good antibacterial and bactericidal effects, has presented great efficacy on the food borne pathogens as well as the pathogenic bacteria in aquaculture. In order to investigate the antibacterial effect of eugenol on the typical pathogenic bacteria in aquaculture, we studied the antibacterial effect of eugenol on Vibrio anguillarum. After 24-hour incubation, the diameter of the inhibition zone was (21.13±0.74) mm at 6 400 μg·mL–1 of eugenol, indicating that V. anguillarum was extremely sensitive to eugenol. It is shown that V. anguillarum did not grow while the eugenol concentration was over 400 μg·mL–1. Hence, the minimum inhibitory concentration (MIC) was 400 μg·mL–1 of eugenol against the bacteria. The solution in the cells of 400 μg·mL–1, 800 μg·mL–1 and 1 600 μg·mL–1 were continually incubated for 24 h after being scribbled on the plate surface. When the concentration of eugenol were over 800 μg·mL–1, no V. anguillarum grew in the plates. It is indicated that the minimum bactericidal concentration (MBC) of eugenol against V. anguillarum was 800 μg·mL–1, and eugenol has excellent antibacterial effects on V. anguillarum.
2019, 15(2): 64-71.   doi: 10.12131/20180203
[Abstract](675) [FullText HTML](250) [PDF 1631KB](18)
Abstract:
We selected 12 microsatellite primers with specificity and polymorphism from 51 microsatellite primers from GenBank by using an automatic nucleic acid protein analysis system. Fluorescent-labeled primers were synthesized to amplify the three cultured populations of M. salmoides from the main culture area of Guangdong. The results show that among the 12 microsatellite loci, three of them were highly polymorphic, four were moderately polymorphic, and the remaining five showed low polymorphic. The genetic diversity of these three populations was low, and the expected heterozygosity (He) was 0.312 5, 0.360 6 and 0.328 4, respectively. Genetic differentiation index and AMOVA analysis among populations show that the genetic differentiation among populations was low, and 85.83% of genetic variation came from difference among individuals within populations. Genetic distance analysis shows that the genetic distance was small and genetic similarity was rather high among the three cultured populations. Genetic structure analysis shows that the three cultured populations originated from the same subgroup. The results suggest that the genetic diversity of the cultured population of M. salmoides in China has decreased significantly at present. Therefore, great attention should be paid to improving and maintaining genetic diversity of the population during the breeding process.
2019, 15(2): 72-82.   doi: 10.12131/20180264
[Abstract](644) [FullText HTML](266) [PDF 1439KB](13)
Abstract:
We obtained the full-length cDNA sequence of GLUT1 from Penaeus monodon by rapid amplification of cDNA ends (RACE), and investigated the expression of GLUT1 at different larval developmental stages, in different tissues, and under low salinity stress by quantitative real-time PCR. The total cDNA sequence of PmGLUT1 open reading frame (ORF) was 1 476 bp, encoding 491 amino acids. From zygote to postlarva stages, the expression of PmGLUT1 fluctuated but showed an increasing trend. The PmGLUT1 was expressed in all tested tissues with the highest expression in gill tissue, followed by hepatopancreas, and the lowest expression was in ovary. After acute low salinity stress, the expression level of PmGLUT1 mRNA in hepatopancreas was significantly higher than that in the control group, while the expression level in gill was significantly lower than that in the control group (P<0.05). The results show that PmGLUT1 might play an important role at different larval developmental stages and under low salinity stress, which provides a theoretical basis for studying the molecular mechanism of PmGLUT1 in larval development and salinity adaptation of P. monodon.
2019, 15(2): 83-92.   doi: 10.12131/20180168
[Abstract](1002) [FullText HTML](440) [PDF 813KB](15)
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We investigated the effects of different levels (0%, 16.67%, 33.33%, 50% and 66.67%, represented as Diet 1# to 5# treatments) of fishmeal replacement by protein mixtures on the survival, growth, physiological metabolism and body biochemical composition of juvenile Chinese mitten crab (Eriocheir sinensis). The results show that: 1) the final body mass, weight gain rate, specific growth rate and hepatosomatic index firstly increased and then decreased with increasing dietary fish meal replacement level, and the highest values were detected in Diet 2# treatment (P<0.05). 2) The highest levels of glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT) and malondialdehyde in hepatopancreas were detected in Diet 4# treatment, while Diet 1# treatment had the highest activity of superoxide dismutase (SOD) in hepatopancreas (P<0.05). The highest activity of GPT in the serum was detected in Diet 5# treatment, and the highest triglyceride (TG) content and SOD activity were detected in Diet 4# treatment (P<0.05), while the highest malondialdehyde (MDA) content was detected in Diet 2# treatment. 3) The contents of crude protein and crude lipid in the juvenile crab's body in Diet 1# treatment were significantly higher than those in the other treatments, while the highest total carbohydrate content was detected in Diet 2# (P<0.05). For the body amino acids, the highest cysteine (Cys) content was detected in Diet 4# treatment, and the highest contents of other amino acids and total amino acids (TAA) were detected in Diet 2# (P<0.05). In conclusion, excessive dietary fishmeal replacement (33%−67%) can reduce the growth performance and accumulation of nutrients in juvenile crab's body, having a negative effect on physiological metabolism. The appropriate dietary fishmeal replacement level is suggested to be about 20%.
2019, 15(2): 93-101.   doi: 10.12131/20180099
[Abstract](716) [FullText HTML](272) [PDF 3435KB](8)
Abstract:
In order to achieve high-value utilization of abandoned Porphyra haitanensis, we studied the enzymatic hydrolysis technique and antioxidant activity of P. haitanensis protein. Single factor test and response surface optimization test were used to screen the optimum protease and enzymolysis parameters based on the indices of hydrolysis degree and reducing power. The antioxidant activity of the hydrolysate was studied by determining the reducing power of hydrolysate and scavenging ability of hydrolysate on the free radicals DPPH, ·OH and \begin{document}${\rm{O}}_2^-$\end{document}·. The results show that neutral protease was the optimal enzyme among the six enzymes. The optimal conditions for the hydrolysis of P. haitanensis proteins were as follows: substrate concentration 35 g·L–1, enzyme dosage 31 200 U·g–1, hydrolysis temperature 45 ℃, pH 7.6, hydrolysis time 5 h. Under these conditions, the hydrolysis degree was 31.37% and the reductive power was 2.2. The scavenging rates for DPPH, ·OH and \begin{document}${\rm{O}}_2^-$\end{document}·were 56.26%, 85.84% and 72.74%, respectively, which indicates that P. haitanensis can be hydrolyzed by neutral protease effectively, and its hydrolysate has good antioxidant activity and application prospects.
2019, 15(2): 102-109.   doi: 10.12131/20180165
[Abstract](1752) [FullText HTML](457) [PDF 4875KB](15)
Abstract:
To explore the mechanism of the quality improvement of low-salt silver carp surimi gel by ultra-high pressure processing (UHPP), we compared the differences of water state and microstructure among high-pressure processed low salt surimi gels (300 MPa, 1.5% NaCl), atmospheric low salt surimi gels (0.1 MPa, 1.5% NaCl) and controlled surimi gel (0.1 MPa, 2.5% NaCl) by analyses of low field nuclear magnetic resonance (LF-NMR), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results of DSC show that the freezing point of frozen water decreased but the bound water content increased significantly from 10.89% to 17.58% after UHPP treatment (P<0.05). The LF-NMR results demonstrate that the spin-spin relaxation time (T21, T23 and T24) of low-sodium surimi gels after UHPP treatment decreased significantly (P<0.05), while the proportion of non-flowing water increased by 9.39% (from 67.29% to 76.65%). In addition, a smooth, uniform and denser network structure was achieved for low-sodium surimi gels at 300 MPa. Therefore, UHPP treatment (300 MPa, 10 min) can increase the bound water content and microstructure of low salt surimi gel.
2019, 15(2): 110-120.   doi: 10.12131/20180226
[Abstract](745) [FullText HTML](274) [PDF 597KB](16)
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In order to provide basic data for intensive processing of oysters, we compared the nutritional components and flavor characteristics of cultivated oysters from different coastal areas of China. Results show that the contents of nutrient substances in the oysters, including protein, fat, ash, glycogen and taurine, were significantly different (P<0.05). It is found that the Zn content in the oysters was the highest among all the detected elements which had significant regional difference (P<0.05). The contents of Zn, Cu, Cd and Pb in the oysters from Shantou were significantly higher than those from the other areas (P<0.05). For the taste-active components, there were abundant delicious free amino acids, flavor-enhancing nucleotides and betaine in the oysters, most of which showed significant difference in different areas and among varieties (P<0.05). The betaine content in the oysters from the north was generally greater than those from the south (lowest in Crassostrea hongkongensis but highest in C. angulata). The main flavor components of oysters from different sea areas were significantly different, and the key volatile flavor compounds (relative odor activity value, ROAV≥1) were aldehydes. Among them, 1-octen-3-one showed the greatest contribution to the overall flavor of oysters from Shantou, but (E,Z)-2,6-nonadienal was the most important flavor substance in the oysters from the other sea areas. It is revealed that significant difference existed in the contents of nutrient composition, taurine, taste substance and volatile flavor composition in oysters from different regions (P<0.05).
2019, 15(2): 121-126.   doi: 10.12131/20180119
[Abstract](719) [FullText HTML](179) [PDF 735KB](17)
Abstract:
We collected 168 female Harpiosquilla harpax and dissected them individually for a comparison of their developmental features of thelycum and ovary, and for ultramicroscopic observation of contents in the milky-white thelycum. The results show that the females had paired ovaries that lied between pericardial sinus and digestive tract, which extended from the back of the breastplate to the tail. The apparent color of ovary changed as follows: colorless−rayish yellow−earthy yellow−light yellow−orange, and the mature ovaries were orange or pink. The gonadosomatic index (GSI) were 1.62±0.53, 2.73±0.44, 3.82±0.48, 6.84±1.04 and 11.63±2.11, respectively. The females had three parallel strips that were visible through the exoskeleton at the sixth, seventh, and eighth thoracic sternites, which were organs for sperm-storage, and the apparent colours of thelycum were changeable (colorless−transparent−light white−turbidity−milk white−dense). The more mature the ovary was, the heavier milk white of the thelycum became. Group of sperms with membranes had been observed in the thelycum contents which were filled with filamentous stroma. The shape of sperm was spherical but without flagellum and acrosome, size of 1~3 μm. The results provide references for further research on the reproductive biology and artificial breeding of H. harpax.
2019, 15(2): 127-132.   doi: 10.12131/20180181
[Abstract](691) [FullText HTML](251) [PDF 783KB](32)
Abstract:
In order to explore the law of oogenesis of Sinibrama taeniatus and provide instruction for artificial reproduction, we observed and described the microscopic structure of its oogenesis process that was divided into five phases: phase of oogonium (Phase I), phase of single-layer follicular cell (Phase II), phase of yolk vesicle (Phase III), phase of yolk filled (Phase IV) and phase of mature oocyte (Phase V). Results of paraffin section reveals that oogonium could be distinguished as two types according to their microscopic characteristics (oogonium at early stage and mitosis). Meanwhile, the early primary oocyte was devided into Phase II, and several small nucleolus appeared at the edge of the nuclear membrane, which was regarded as the sign of beginning of little growth period. Yolk vesicles appeared in Phase III and the yolk began to accumulate and mainly existed in the form of yolk granule when the yolk vesicles increased to 3−5 layers. After entering Phase IV, the yolk deposited into yolk platelet, and the yolk vesicles were squeezed to the perivitelline area and formed cortical vesicles. After the oocyte was mature, the area of cortical vesicles exhibited as lumps or particulates, and was dyed orange by hematoxylin-eosin staining.
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[Abstract](1)
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In this study, melanocortin receptor-5 (mc5r)gene of Spinibarbus hollandi was cloned by homology cloning and genome walking method. Bioinformatics methods were used to analyze the gene sequence and deduced amino acid sequence of mc5r. The tissue distribution, diurnal change and starvation response of mRNA expression were detected by real-time PCR. The full length of mc5r gene was 1 947 bp with one exon of 987 bp encoding 329 amino acids. According to multiple sequences alignment and phylogeny evolution analysis, the homology of S. hollandi mc5r amino acid sequence with Cyprinus carpio and Sinocyclocheilus rhinocerous reached 98%. S. hollandi mc5r was significant expression in brain, followed by diencephalon and heart, relatively less in mesencephalon and cerebellum, and weak in kidneys, stomach, muscles, spleen, intestines, gonadal, liver, medulla oblongata and eye. The diurnal periodicity expression of mc5r mRNA changed with the day and night regularly. In starvation refeeding experiment, after starvation the expression of refeeding fish increased significantly, but then decreased. It indicated that mc5r may have some effects on food intake regulation.
[Abstract](2)
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We collected 721 individuals of Acanthopagrus schlegeli in Daya Bay in January, March, April, August -December, 2018, and then investigated the annual variation of reproductive characteristics of A. schlegeli in Daya Bay so as to provide a theoretical basis for its artificial breeding and conservation. The results show that: 1) the spawning period falls between November and March. The total length ranged 175−487 mm for females (averge 297.92±56.61 mm). The body mass ranged 90.96−1 907.12 g for females (average 511.36±307.53 g). The total length ranged 110−440 mm for males (average 237.61±61.05 mm). The body mass ranged 21.92−1 370.00 g for males (average 277.76±210.33 g). The full lengths of females are significantly longer than those of males (P<0.001). 2) The gonad maturity coefficient and gonad development indicate that the reproductive period of A. schlegeli in Daya Bay was from November to March. 3) The existence of androgynous individuals indicates that the species will undergo sexual reversal, and the males will mature first and then change to females. 4) The total lengths (TL) at 50% sex maturity for females and males were 248.52 mm and 148.03 mm, respectively. 5) A. schlegeli is a multiple spawner with indeterminate fecundity by oocyte size-frequency distributions. The number of the individual fertility ranged from 84 100 to 2655 168 granules (average 728 732±499 547). The relative fertility of total length was 380.54−8 271.55 eggs·mm−1 (2 731.44±1 630.93 egg·mm−1). The relative fertility of body mass was 277.58−3 592.83 eggs·g−1 (average 1 443.87±766.82 eggs·g−1). There was a linear correlation among absolute fecundity and total length, body mass and gonadal mass.
[Abstract](4)
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To explore the carrying capacity of fishery resources in the coastal waters of Dapeng Peninsula, Shenzhen, in consideration of the actual situation of that sea area, we established an evaluation index system by referring to the "Resource and Environmental Carrying Capacity Monitoring and Early Warning Technology Method (Trial)" and the evaluation methods of fishery resources carrying capacity at home and abroad. Based on the survey data of fishery resources in that waters every autumn in 2012 to 2016, we applied two methods [comparing the data between 2016 and the previous 3 years (2013 to 2015) and comparing the data between 2016 and the previous 4 years (2012 to 2015)] to evaluate the carrying capacity. The results of both methods show that the swimming animal index had a downward trend. The fish spawn and larvae index decreased significantly. The fishery resources carrying capacity was almost overloaded. Therefore, it is recommended to strengthen the monitoring and investigation of fishery resources as well as the evaluation and early warning of fishery resource carrying capacity, so as to provide technical support for promoting the restoration and protection of fishery resources and the maintenance of breeding.
[Abstract](4)
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In order to study the effects of desiccation stress on crayfish (Procambarus clarkii) during crayfish seedling transportation, we investigated the antioxidant stress ability and survival rate of crayfish to desiccation stress (6 h, 12 h, 18 h, 24 h) and resubmersion in water (1 h, 6 h, 12 h) at (20±1) ℃ and with (50±5)% RH. The results show that the desiccation time should not exceed 18 h; the mortality rate at 24th hour was 53.3%, but no juveniles died during the resubmersion. During desiccation, no significant difference was observed in total antioxidant capacity (T-AOC) (P>0.05); the superoxide dismutase (SOD) significantly reduced; the catalase (CAT) activity increased with time; the malondialdehyde (MDA) content reached the maximum value after 24 h (P<0.05), and the blood sugar and muscle lactic acid increased significantly with time (P<0.05). During the resubmersion period, the SOD and CAT activities fluctuated without an obvious rule; the MDA content restored to normal level after 12 h but the T-AOC maintained a high level. The lactate contents of 6 h and 12 h groups restored to the control level after resubmersion for 1 h. The blood sugar contents of all treatment groups were always higher than that of the control group (P<0.05). It is shown that the MDA content and SOD activity are more sensitive to desiccation stress, which can be regarded as immune indices. The MDA, blood sugar and lactate contents can reflect the physiology of crayfish during resubmersion period.
[Abstract](55)
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TRIAP1 can participate in vivo responses by inhibiting apoptosis. In order to analyze the expression regulation of TRIAP1 and miRNAs that regulate TRIAP1's expression under Vibrio harveyi challenge in Penaeus monodon, we obtained the P. monodon TRIAP1 gene (PmTRIAP1) cDNA by RACE, then detected the tissue distribution of PmTRIAP1 by quantitative real-time PCR (qRT-PCR), and investigated the expression association between PmTRIAP1 and its related miRNAs under V. harveyi challenge. The results show that the full-length PmTRIAP1 cDNA sequence was 2 522 bp, containing an 11 bp 5' non-coding region (UTR), a 2 289 bp 3'-UTR, and a 222 bp open reading frame encoding 73 amino acids. The qRT-PCR analysis shows that PmTRIAP1 was ubiquitously expressed in all the tested tissues and the highest expression level was obtained in the hemocyte. The expression of PmTRIAP1 decreased significantly, however, the expressions of Pm-miR-145-3p and Pm-miR-454-3p increased significantly under V. harveyi challenge, which suggests that the expression levels of PmTRIAP1 and Pm-miR-145-3p, Pm-miR-454-3p were negatively correlated. Dual luciferase reporter assay shows that Pm-miR-145-3p and Pm-miR-454-3p can bind PmTRIAP1 3'UTR to reduce luciferase activity. It is suggested that both Pm-miR-145-3p and Pm-miR-454-3p can target regulate the expression of PmTRIAP1.
[Abstract](45)
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In order to develop a DNA vaccine against Cyprinid herpes virus 3 (CyHV-3), also known as Koi herpes virus (KHV), CyHV-3 ORF65 was inserted into pEGFP-N1 to construct recombinant plasmid pEGFP-ORF65. The expression of pORF65-EGFP fusion protein in Cyprinus carpio var. Jian was confirmed by transfection and in vivo imaging experiments. The recombinant plasmid was injected into the tail stalk of the carp seedlings at dosage of 3 μg·tail−1 for about 10 g and immunized for three times. ELISA detection shows that pEGFP-ORF65 could significantly increase the level of serum specific antibodies. The challenge test shows that 21 d after CyHV-3 challenge, the survival rates of PBS group, pEGFP-N1 group and pEGFP-ORF65 group were 25%, 30% and 90%, respectively, which significantly improved the survival rate of the carp seedlings (P<0.01). The study provides a basis for the application of ORF65 as a target gene of DNA vaccine in the prevention and control of CyHV-3.
[Abstract](48)
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We examined genetic diversity of 19 Bahaba flavolabiata samples collected from the Pearl River estuary based on microsatellite markers, so as to provide references for the identification of its germplasm resources and future breeding. The results show that the number of alleles (Na) in each of the 29 microsatellite loci was 2−7, with a total number of 121 alleles. The average number of alleles in each locus was 4.17. The effective number of alleles (Ne) was 1.060 6−6.056 1, with a sum of 85.205 0. The average values of the observed heterozygosity (Ho) and the expected heterozygosity (He) were 0.659 3 and 0.597 3, respectively. The value of polymorphism information content (PIC) was 0.055 5−0.813 7, with an average of 0.542 3, and 19 loci showed high polymorphism. Five loci deviated significantly from the Hardy-Weinberg equilibrium (corrected P≤0.036). The allelic richness (Rs) was 2−6.97 6, with a sum of 119.638. The genetic diversity (GD) was 0.059−0.856. It is suggested that most of the SSR loci developed in this study are highly polymorphic, and the genetic diversity of B. flavolabiata population is at a higher level.
[Abstract](52)
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In order to study the new non-CO chromogenic method of tilapia fillets, and to achieve a safe and effective coloring process, we used color difference value as the main evaluation index for the fillets' color. Based on the single-factor test of sodium nitrite concentration, sodium bicarbonate concentration and soaking time, we used the Box-Behnken center design principle to optimize the response surface test of the chromogenic scheme. The results show that soaking in a composite solution of sodium nitrite concentration of 0.4 g·kg−1 and sodium bicarbonate concentration of 5.0 g·kg−1 for 22 min performs well. The Δa* of the red meat was 1.97, an increase of 17.35%. The overall color of the fillets was good. A new method of non-CO chromogenic technology of tilapia fillets is obtained.
[Abstract](52)
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Sargassum hemiphyllum, a common species in coastal areas of Guangdong Province, was selected to study its physiological response to different concentrations of Cd2+ stresses and its tolerance to heavy metal cadmium (Cd2+) in laboratory semi-static experiments, which provids a basis for remediation of heavy metal pollution in that area. The results show that chlorophyll a (Chl-a), carotenoid (Car), soluble protein (SP), soluble sugar (SS) and antioxidant enzyme activity (SOD and CAT) had no significant difference with the control (P>0.05) at Cd2+ concentration of 0.1 mg· L−1 in S. hemiphyllum. The contents of Chl-a, Car, SP, SS, SOD and CAT in stress groups increased significantly with ρ(Cd2+) of 0.5 mg∙L−1, 2.5 mg∙L−1 and 12.5 mg∙L−1, respectively (P<0.05); there was no significant difference in malondialdehyde (MDA) contents between the stress groups and the control with ρ(Cd2+) of 0.1 mg∙L−1 and 0.5 mg∙L−1 (P>0.05); the MDA contents in the stress groups were significantly higher than that in the control with ρ(Cd2+) of 2.5 mg∙L−1 and 12.5 mg∙L−1 (P<0.05). Therefore, S. hemiphyllum had stronger stress resistance under Cd2+ concentration (≤0.5 mg∙L−1) and excessive Cd2+ stress (>0.5 mg∙L−1), which was harmful its photosynthesis and antioxidant function.
[Abstract](61)
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We collected 57 individuals of Charybdis japonica from the offshore waters of Nantong, Jiangsu Province, China to analyze their eyestalks microstructure, explore their age and growth, and establish a corresponding growth model. The results show that the eyestalks microstructure of C. japonica consists of four parts: epicuticle, exocuticle, endocuticle and menbranous. The growth lines that can be used for research mainly exist in endocuticle. By analyzing the biological data and growth pattern, in addition to application of AIC method, we found that in seven commonly used growth functions, a linear function relationship is presented between carapace length and carapace width, and a power function relationship is presented among carapace length, carapace width and body mass. However, the relationship among growth lines and carapace length, carapace width as well as body mass is expressed by logistic function relationship.
[Abstract](80)
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We investigated the selection adaptability and spatial distribution ratio, distribution of sex ratio inside or outside different caves, as well as the quantity and sex ratio in single cave of Procambarus clarkii in two kinds of caves (staked bamboo tube and PVC tube) during artificial breeding. The results show that P. clarkii tended to hide in caves (Group A: 83.47%, Group B: 89.87%), especially in bamboo cave [Group B: bamboo tube (71.80%) and PVC tube (11.63%)]. Vertical placement of the cave will affect the distribution of P. clarkii which prefered to hide in the caves at middle and lower layer as well as at lower layer, and the quantity reduced from bottom to top. P.clarkii had a phenomenon of polygyny cohabitation, but the laws of male and female distribution in different vertical spaces were not obvious, with the highest ratio of male and female in the lowerest layer of Group A (3.43:1) and the uppermost layer of Group B bamboo cave (2.86:1).
[Abstract](102)
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To investigate the effects of substitution of fish meal by fermented soybean meal on the growth performance and serum biochemistry of Trachinotus ovatus, we have formulated five experimental diets, adding 0% (FM), 25% (FSM25), 50% (FSM50), 75% (FSM75) and 100% (FSM100) fermented soybean meal to replace fish meal. In order to eliminate the effects of limiting amino acids, we added 0%, 0.10%, 0.22%, 0.35% and 0.45% lysine, as well as 0%, 0.14%, 0.27%, 0.41% and 0.54% methionine, respectively. The results show that the weight again rate, specific gain rate, specific growth rate and feed intake did not have significant difference among FSM25, FSM50 and FM groups (P>0.05), but the feed conversion ratio in FSM100 group was significantly higher than that in FM group (P< 0.05). There was insignificant difference in the muscle moisture, ash, crude protein, crude fat contents between the fermented soybean meal groups and FM group (P>0.05). The serum aspartate aminotransferase (AST) activities and total protein (TP) contents in FSM75 and FSM100 groups were significantly higher than those in FM group (P< 0.05). The activities of alanine aminotransferase (ALT) and superoxide dismutase (SOD) in FM100 group were significantly higher than those in FM group (P< 0.05). The relative expressions of IGF-1 and GH genes in FSM75 and FSM100 groups were significantly lower than those in FM group (P< 0.05). In summary, by adding limiting amino acids, the substitution of fish meal by fermented soybean meal not exceeding 50% does not have adverse affects on T. ovatus. According to the regression curve, the substitution level of 17.5% achieves the best effects.
[Abstract](101)
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In order to promote the development and utilization of Grateloupia and provide reference for its food and processing, we investigated the species composition, biomass, growth environment and taste of Grateloupia on floating rafts in Nanao, Shantou, Guangdong Province and Dongshan, Fujian Province once a month from January to April 2018. The results show that the water velocity and temperature were 0.039−0.985 m·s−1 and 19−23 ℃, respectively, and the water velocity in Dongshan was greater than that in Nan'ao. By morphology, cross-section and rbcl sequence analyses of the samples collected from the floating raft, we found eight Grateloupia species on the floating raft, which were G.lanceolata, G. turuturu, G.taiwanensis, G.carnosa, G.livida, G. haimensis, G. prolongata and G. sparsa. The dominant species were G. lanceolata and G. turuturu whose highest biomass were 901.26 g·m−1 and 352.9 g·m−1, respectively. The G. lanceolata grew with higher water velocity had longer body length that could reach 142 cm. The taste of G. turuturu and G. prolongata was the worst but that of G. lanceolata and G. livida was the best. G. lanceolata and G. livida had better taste in January to March than in April. It is worth developing G. lanceolata as marine vegetable for its bigger biomass and size as well as its better taste.
[Abstract](89)
Abstract:
Six isonitrogenous and isoenergetic diets supplemented with different levels of vitamin D3 (0, 1 000 IU·kg−1, 2 000 IU·kg−1, 4 000 IU·kg−1, 8 000 IU·kg−1, 100 000 IU·kg−1) were formulated to evaluate the requirement of vitamin D3 to Epinephelus coioides, namely Diet 1, Diet 2, Diet 3, Diet 4, Diet 5 and Diet 6. Diet 3 obtained higher weight gain rate, specific growth rate and feed efficiency than the other groups (P<0.05). With dietary supplemental vitamin D3 higher than 2 000 IU·kg−1, the intraperitoneal fat ratio (IPF) and viscerosomatic index (VSI) decreased with increasing dietary vitamin D3 levels significantly (P<0.05). The protein contents in whole body and muscle decreased with increasing dietary vitamin D3 levels (P<0.05), but the lipid and ash contents showed no difference in whole body and muscle among all the groups. When the dietary supplemental vitamin D3 lower than 2 000 IU·kg−1, the calcium (Ca) and phosphorus (P) contents in fish bone were positively correlated with the vitamin D3 levels. Based on Ca and P contents in bones, the optimal supplementation level of vitamin D3 in practical diet should be 2 000 IU·kg−1.
[Abstract](109)
Abstract:
Based on high throughput sequencing technology Illumina MiSeq, we analyzed the effects of periodic hypoxia stress on intestinal microflora structure of Lateolabrax maculatus. The results show that hypoxia caused a significant increase in the diversity and richness of intestinal microflora (P<0.05). The species richness was rather different between the two groups. The operational taxonomic units (OTUs) of hypoxic group were significantly more than those of normoxic group (P<0.05). At the level of Class classification, the dominant bacteria of both groups were Proteobacteria, Firmicutes and Bacteroidetes. Compared with the normoxic group, the relative abundance of Proteobacteria decreased significantly in hypoxic group, while that of Bacteroidetes increased significantly (P<0.05). Meanwhile, at the level of Genus classification, the relative abundance of Alphaproteobacteria and Bacilli in hypoxic group decreased significantly, while those of Clostridia, Gammaproteobacteria and Bacteroidia increased significantly (P<0.05). Periodic hypoxia stress also led to an increase of the relative abundance of anaerobes or facultative anaerobes (Anaerolineaceae, Lachnospiraceae and Ruminococcaceae) and oxygen-producing bacteria (Chlorobiaceae) in the intestine of L. maculatus.