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[Abstract](258) [FullText HTML](58) [PDF 3819KB](6)
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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 25, 3, 2 and 3, respectively. The Shannon-Wiener biodiversity index of fish, crustaceans, cephalopods and shellfish increased 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 apositive role in the conservation and proliferation of fishery resources.
[Abstract](127) [FullText HTML](81) [PDF 17036KB](4)
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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 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 thatPmGLUT1 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.
[Abstract](191) [FullText HTML](49) [PDF 791KB](9)
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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.
[Abstract](262) [FullText HTML](62) [PDF 598KB](6)
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In order to provide basic data for intensive processing of oysters, we compared the nutritional components and flavor characteristic 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&lt;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&lt;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&lt;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&lt;0.05). The betaine content in the oysters from the north was generally greater than those from the south (lowest inCrassostrea 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&lt;0.05).
[Abstract](335) [FullText HTML](99) [PDF 1033KB](3)
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In order to explore the regulation rule of spermatozoa motility of Schizothorax irregularis, and to improve 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&lt;0.05). The maximum fast movement time ofS. 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&lt;0.05). The maximum fast movement time ofS. irregularisspermatozoa 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&lt;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&lt;0.01), and interaction effect was significant (P&lt;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 ofS. irregularis spermatozoa.
[Abstract](330) [FullText HTML](204) [PDF 691KB](8)
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Fish anesthetic eugenol, which has high antibacterial and bactericidal effect, 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.
[Abstract](207) [FullText HTML](80) [PDF 782KB](11)
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In order to explore the law of oogenesis in 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 was 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.
[Abstract](361) [FullText HTML](154) [PDF 739KB](9)
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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 found in Diet 2# treatment (P&lt;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&lt;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&lt;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&lt;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&lt;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%.
[Abstract](321) [FullText HTML](104) [PDF 1043KB](2)
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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 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&lt;0.05); however, there was no significant difference between both groups (P&gt;0.05), including chlorophylla, 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.
[Abstract](478) [FullText HTML](171) [PDF 1050KB](3)
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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&lt;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&lt;0.05), and 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.
[Abstract](239) [FullText HTML](68) [PDF 1212KB](6)
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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 a 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&lt;0.05), but a limited impact on the daily output value, CPUE, fishing rate and fishing structure (P&gt;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.
[Abstract](246) [FullText HTML](68) [PDF 3434KB](5)
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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 optimum conditions for the hydrolysis of P. haitanensis proteins were as follows: substrate concentration 35 g·L–1, enzyme dosage 31200 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.
[Abstract](249) [FullText HTML](42) [PDF 735KB](9)
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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 was changeable as follows: colorless-rayish yellow-earthy yellow-light yellow-orange, and the matured 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 matured ovary was, the heavier milk white of 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.
[Abstract](208) [FullText HTML](56) [PDF 845KB](10)
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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 origined 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.
[Abstract](187) [FullText HTML](76) [PDF 967KB](10)
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In order to investigate the size selectivity of codend of shrimp beam trawl for Metapenaeus ensis, with the 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 codend were 51.52, 60.84, 63.21 and 64.53 mm, respectively, and the mean selection ranges (SR) were 16.48, 14.31, 12.84 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, 82.38 and 95.39 mm, respectively, and the mean SRs were 6.93, 6.39 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, 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.
[Abstract](226) [FullText HTML](85) [PDF 1446KB](6)
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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, sputum 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.
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2019, 15(1).
[Abstract](128) [PDF 1276KB](3)
Abstract:
2019, 15(1): 1-9.   doi: 10.12131/20180112
[Abstract](293) [FullText HTML](147) [PDF 8333KB](11)
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Based on the data of fishery resources surveys in the Yangtze River estuary from 2012 to 2014, the spatial co-occurrence patterns and influencing factors of fish communities in that area were analyzed by using probability model and network analysis method. The results show that the fish community pattern in the Yangze River estuary is mainly the random co-occurrence of species. The influence of neutral elements was dominant in community construction, and the effect of random factors driven by environmental change on interspecific co-occurrence was greater than that of interspecific interaction. There was significant seasonal difference in the patterns of interspecific co-occurrence, which was mainly related to the seasonal changes of migratory marine fish and estuarine sediment fish. The seasonal replacement of fish species with high weighted degree and betweenness centrality might also have caused the high number of randomly associated pairs of species. It is also shown that Collikithys lucidus has strong ability to control information exchange within the community and is at the core of the fish community structure in the Yangtze River estuary.
2019, 15(1): 10-19.   doi: 10.12131/20180041
[Abstract](254) [FullText HTML](137) [PDF 1003KB](8)
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We evaluated the value of ecosystem service before and after the construction of marine ranching in Zhelin Bay by using the theory of ecosystem service. Besides, we investigated the spatial distribution characteristics of ecosystem service value in different functional areas, such as cage culture area, seaweed culture area, shellfish farming area, artificial reef area as well as enhancement and release area using ArcGIS. The results show that the ecosystem service value of Zhelin Bay marine ranching had increased from 586.13 million CNY to 673.70 million CNY during 2011−2013. However, the value structure did not change significantly, showing the highest value of provisioning service, followed by cultural service value, and relatively low value of regulating service. The spatial distribution characteristics of different functional areas in Zhelin Bay marine ranching are roughly as follows: cage culture area>seaweed culture area>shellfish farming area>artificial reef area>enhancement and release area.
2019, 15(1): 20-30.   doi: 10.12131/20180141
[Abstract](314) [FullText HTML](146) [PDF 802KB](17)
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We investigated the composition of the stomach contents of 138 longnose lancetfish (Alepisaurus ferox) collected from September 2017 to January 2018 by the Chinese Longline Fisheries Observer Programme in the western tropical Pacific Ocean (165°45′E−178°00′W, 03°02′S−18°34′S). A total of 61 species from 44 families, belonging to six prey groups (Fish, Mollusca, Crustacea, Polychaeta, Cnidaria and Thaliacea) were identified. Cannibalism and plastic debris ingestion were also observed. The obtained values of Shannon-Wiener diversity index (H'), Pielou evenness index (J') and dominance index (D) of A. ferox's diet composition were 2.71, 0.67 and 0.12, respectively. The result of index of relative importance (IRI) analysis indicates that Mollusca was the dominant prey with IRI of 7 573.31 which accounted for 53.11% of total IRI. At family level, Sternoptychidae, Alepisauridae, Carinariidae, Pterotracheidae, Bolitaenidae, Onychoteuthidae, Oplophoridae, Platyscelidae, Eurytheneidae and Alciopidae were the most important preys of A. ferox.
2019, 15(1): 31-41.   doi: 10.12131/20180144
[Abstract](319) [FullText HTML](237) [PDF 1136KB](15)
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To compare the physiological and ecological characteristics of inoculant of photosynthetic bacteria and Rhodopseudomonas palustri, we analyzed the degradation effects of the inoculant PG and the strain PSB-1 with different initial amounts of bacteria on ammonia nitrogen ( \begin{document}${\rm NH}^+_4$\end{document} -N), nitrite nitrogen ( \begin{document}${\rm NO}^-_2$\end{document} -N), nitrate nitrogen ( \begin{document}${\rm NO}_3^-$\end{document} -N) and phosphate ( \begin{document}${\rm PO}_4^{3-}$\end{document} -P) in experimental water. Then we studied the dominant bacteria composition of inoculant of photosynthetic bacteria PG, as well as the number of bacteria and microbial community composition in experimental water at the end of the experiment by high-throughput sequencing. The results show that the inoculant PG group had certain degradation effects on \begin{document}${\rm PO}_4^{3-}$\end{document} -P, \begin{document}${\rm NO}_3^-$\end{document} -N and \begin{document}${\rm NO}_2^-$\end{document} -N in experimental water. The maximum degradation rates of PG for \begin{document}${\rm PO}_4^{3-}$\end{document} -P, \begin{document}${\rm NO}_3^-$\end{document} -N and \begin{document}${\rm NO}_2^-$\end{document} -N were 40.98%, 28.28% and 20.12%, respectively. Moreover, the strain PSB-1 group only had certain degradation effect on \begin{document}${\rm NO}_2^-$\end{document} -N and \begin{document}${\rm PO}_4^{3-}$\end{document} -P. The maximum degradation rates of PSB-1 were 14.19% and 9.88%, respectively. The dominant bacteria of the inoculant PG belonged to Rhodopseudomonassp.. After 7 d of experiment, the number of bacteria and microbial community structure in the experimental group changed, and the number of bacteria in the water increased, forming a microbial structure with heterotrophic bacteria as the dominant bacteria. It is indicated that the inoculant of photosynthetic bacteria PG has better effect on the degradation of water quality factors than R. palustris PSB-1. However, there is a certain gap between both things and the reported degradation efficiency of photosynthetic bacterial strains.
2019, 15(1): 42-53.   doi: 10.12131/20180127
[Abstract](305) [FullText HTML](139) [PDF 1087KB](13)
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We constructed the sRNA srvg17985 knock-out mutant in Vibrio alginolyticus ZJ-T by using homologous recombination, so as to compare the biological characteristics of growth in LBS medium, motility, extracellular protease secretion, iron utilization, antibiotic resistance and metabolism between the wild type and the mutant strains. The results show that the absence of sRNA srvg17985 did not affect the growth in LBS medium, motility, extracellular protease secretion, iron utilization, antibiotic resistance and most of the tested carbon and nitrogen sources metabolism in V. alginolyticus. However, the mutant showed better utilization of laminarin, pectin and dihydroxyaceton, and gained the ability to utilize alanine-aspartic acid (Ala-Asp) as the sole nitrogen source.
2019, 15(1): 54-62.   doi: 10.12131/20180135
[Abstract](259) [FullText HTML](125) [PDF 848KB](11)
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Microsatellite DNA markers were used to assess the genetic diversity of first filial generation of seven introduced Litopenaeus vannamei populations, named TH-A1, TH-A2, TH-B, US-C1, US-C2, US-C3 and US-C4, respectively. The results show that the seven populations had varying polymorphism at 12 microsatellite loci, with the mean allele number (Na) ranging from 3.333 to 6.167. The mean values of expected (He) and observed (Ho) heterozygosity were 0.477–0.670 and 0.370–0.505, respectively. The polymorphic information content (PIC) for each population varied from 0.414 to 0.623. For Hardy-Weinberg equilibrium test, 44 out of 88 exhibited significant deviation (P<0.05), which corresponded with the fact thatHe was slightly higher than Ho. Cluster analysis shows that the seven populations were clustered into three branches (TH-A1; US-C1, US-C2 and TH-A2; the rest). It is indicated that the genetic characteristics vary in different cultured populations of L. vannamei. The results provide references for further exploration of relevance between genetic characteristics and practical performance of L. vannamei.
2019, 15(1): 63-68.   doi: 10.12131/20180182
[Abstract](598) [FullText HTML](433) [PDF 557KB](8)
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In order to investigate the negative regulater role of myostatin (MSTN) in growth and development of adductor of Chalmys nobilis, we analyzed the promoter sequence of MSTN of C. nobilis. The results show that the promoter sequence was 1 358 bp in length, including four transcription start sites (TSS). The core promoter region was located from –100 bp to –51 bp. Two kinds of cis-regulatory element, a TATA-box (located from –92 bp to –86 bp) and two E-boxes, were detected in promoter. Potential transcription factor binding sites including MEF2, MEF3, FoxO, MTBF, MyoD and so on were found in promoter. No CpG island was found. Six luciferase expression vectors with different lengths of MSTN promoter were successfully constructed and transiently transfected into 293T cells for an analysis of the activity of dual luciferase reporter gene. It is shown that all the six promoter sequences had transcriptional activity, with PGL-534 the highest, followed by PGL-274, PGL-22 and PGL-102, and PGL-995 the lowest. There might be some binding sites of potential negative transcription factors from –216 bp to –364 bp, and potential positive transcription factors from –364 bp to –825 bp.
2019, 15(1): 69-76.   doi: 10.12131/20180065
[Abstract](242) [FullText HTML](124) [PDF 669KB](10)
Abstract:
To determine the optimal dietary vitamin B2 requirement of juvenile golden pompano (Trachinotus ovatus), six experimental diets were formulated which contained 0 mg·kg–1, 4.4 mg·kg–1, 6.2 mg·kg–1, 8.0 mg·kg–1, 11.3 mg·kg–1 and 15.5 mg·kg–1 of vitamin B2. Each diet was assigned to three parallels of 25 fish [initial mass of (11.63±0.17) g] which were fed twice daily for eight weeks. The results show that the weight gain rate and specific growth rate of the fish fed with diet of 4.4 mg·kg–1 vitamin B2 were significantly higher than those of 0 mg·kg–1 group (P<0.05), and the activities of aspartate aminotransferase and alanine aminotransferase in the serum were significantly lower than those in 0 mg·kg–1 group (P<0.05). No significant effect was found on the fish coefficient, survival rate, liver vitamin B2 content, serum immune parameters, crude protein and crude fat content in whole body, moisture, crude fat and crude ash in muscle (P>0.05); the liver D-AAO activity in 6.2 mg·kg–1 group was significantly higher in 0 mg·kg–1 group (P<0.05). Broken-line model analysis estimates that the dietary vitamin B2 requirement of juvenile golden pompano is 4.23 mg·kg–1 for optimal growth, and 6.24 mg·kg–1 for maximum liver D-AAO activity.
2019, 15(1): 77-84.   doi: 10.12131/20180164
[Abstract](317) [FullText HTML](262) [PDF 797KB](6)
Abstract:
In order to study the sterilization effect of fresh tilapia fillets with slightly acidic electrolyzed water, the single factor and response surface experiment were adopted to establish the mathematical model between the factors and response values, and the best sterilization conditions were determined. The results show that the best bactericidal condition was 35.00 mg·L–1 of available chlorine concentration, 22 min for soaking time and 1∶6 (mV ). Under this condition, the killing logarithm value of bacterial colony was (0.735±0.001) lg (CFU·g–1), and the bactericidal rate was (81.59±0.04)%.
2019, 15(1): 85-92.   doi: 10.12131/20180184
[Abstract](329) [FullText HTML](142) [PDF 726KB](10)
Abstract:
In order to study the difference of fatty acid and phospholipid composition in different families and species of Perciformes freshwater fish, we analyzed the fatty acids and phospholipids in muscles of Scortum barcoo, Perca fluviatilis, Lucioperca lucioperca, Micropterus salmoidesandOreochromis mossambicus by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC-ELSD). Twenty-one kinds of fatty acids had been detected in those fish. Eight kinds of common fatty acids were detected (C14:0, C16:0, C18:0, C16:1, C18:1, C18:2, C20:5 and C22:6). Polyunsaturated fatty acids (PUFA) were rich and the content was higher than 35% except for S. barcoo (26.81%). Six kinds of phosphatidylcholine were detected in those fish, including phosphatidylethanolamine (PE), sphingomyelin (SM), phosphatidylinositol (PI), lysophosphatidylcholine (LPC), phosphatidylcholine (PS) and phosphatidylcholine (PC). The PC contents in those fish muscles phospholipids were the highest, accounting for 45.84%−62.55% of total phospholipid, followed by PE and PI contents. The PS and SM contents were relatively low, accounting for only 2.19%−5.27% and 2.06%−3.65% of total phospholipids.
2019, 15(1): 93-99.   doi: 10.12131/20180089
[Abstract](591) [FullText HTML](794) [PDF 564KB](8)
Abstract:
In order to investigate the chloramphenicol residues in commercially available shellfish and to assess their exposure, we collected 300 shellfish samples which were determined by LC-MS/MS and analyzed by @risk software using Monte Carlo method. The daily intake and estimated dietary exposure were simulated, and the margins of exposure were calculated. The results show that 33 samples were determined to have chloramphenicol residues in 2015. The MOE value of the general population was 15 361, presenting a medium risk (according to the evaluation criteria of the Canadian Ministry of Health). The MOE value of the high exposure population was 5 208, also presenting a medium risk. In 2016, three samples were determined to have chloramphenicol residues. The MOE value of the general population was 10 3627, presenting a medium risk. The MOE value of the high exposure population was 34 722, presenting a medium risk. In 2017, no samples were determined to have chloramphenicol residues, presenting no risk.
2019, 15(1): 100-105.   doi: 10.12131/20180083
[Abstract](323) [FullText HTML](214) [PDF 560KB](6)
Abstract:
In order to establish a rapid and convenient method for fish species identification of Siganidae, we obtained 46 COⅠ genes from 10 species and downloaded 27 COⅠ genes from 12 species from BOLD and GenBank to study the COⅠ gene's genetic composition, intraspecific and interspecific genetic distance, codon characteristics and molecular phylogenetic tree. The results show that the average base composition of 73 COⅠ genes was T: 28.9%, C: 28.7%, A: 24.6% and G: 17.8%. The content of G+C (46.5%) was lower than the content of A+T (53.5%) and the base composition showed obvious bias. The average interspecific genetic distance was 0.098, which was 49 times the length of the genetic distance within the species (average: 0.002). The phylogenetic tree reveals that Siganus unimaculatus and S. vulpinus clustered into one branch among 19 species of basket fish. The other 17 species (89.5%) clustered in monophyletic groups at genus level. It is shown that the technology of DNA barcoding can be used for fish species identification of Siganidae.
2019, 15(1): 106-112.   doi: 10.12131/20180066
[Abstract](333) [FullText HTML](128) [PDF 705KB](7)
Abstract:
The transcripts of Micropterus salmoides were obtained by RNA-seq technology to conduct a transcriptomic analysis. A total of 35 659 unigenes were generated by de novo assembly with an average length of 738 bp and N50 of 1 052 bp. The unigenes were assessed for length distribution and GC content. The sequencing data were of high quality and reliability. A total of 15 832, 21 279, 14 524, 16 973, 15 024 and 11 185 unigenes were annotated from the KOG, Nr, Pfam, Swiss-Prot, GO and KEGG databases, respectively, among which 5 617 were annotated in all the databases and 17 253 were annotated in at least one database. Blasted with KEGG pathway, 11 185 unigenes were annotated, belonging to 267 categories. Of all the pathways, the number of unigenes joining in the signal transduction was the most (1 349, 12.06%). Finally, 4 030 SSRs were identified. The results provide rich data to understand transcriptome information of M. salmoides and lay the foundation for further research on functional gene cloning, genomics, genetic diversity analysis, molecular marker exploitation and genetic improvement in M. salmoides.
2019, 15(1): 113-118.   doi: 10.12131/20180139
[Abstract](254) [FullText HTML](113) [PDF 789KB](13)
Abstract:
We used histological methods to observe the gonadal development of Megalobrama terminalis, and decribed the morphology in each type of germ cell and structural feature in ovary and testis. The results indicate that M. terminalis is a one-time spawning type fish, whose ovary development type is partially synchronous. The ovary was thin or flat. The ovarian development had oogonia, monolayer follicular phase, yolk vesicle phase, yolk filling phase, maturation phase and degeneration phase. Occurrence of oocytes had undergone three stages: oogonia, primary oocytes and secondary oocytes. The nucleolar efflux phenomenon occurred in the primary oocytes of ovary from the late Stage II to the early Stage III. The testis was thin or straight with a leaflet structure. The spermatogenesis had undergone five stages: spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid and sperm. The spermatids were filled with spermatozoa and the spermatic capsules disappearred in breeding season.
2019, 15(1): 119-123.   doi: 10.12131/20180137
[Abstract](278) [FullText HTML](144) [PDF 463KB](19)
Abstract:
Grateloupia, 42 species reported in China, are economic red algae which are widely applied in food, chemical industry and medicine (detoxication, expelling parasite, antioxidant, anticoagulant, antitumor and antioxidation). The paper reports on the research progress in the classification, reproduction, physiology, ecology and breeding, as well as points out the problem of utilization of Grateloupia, providing references for the breeding and utilization of Grateloupia.
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[Abstract](70)
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In order to provide scientific guidance for the management and protection of nekton in different seasons, 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) studies 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](63)
Abstract:
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). We found 5?17 alleles (mean 10.6). The observed and expected heterozygosities varied 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 microsatellites will be useful for further population genetic analysis.
[Abstract](86)
Abstract:
We observed and drawn the external morphology, counted the number of dorsal fin rays, caudal fin rays, anal fin rays, pectoral fin rays, so as to conduct a regrassion analysis of morphological features of 131 Thamnaconus septentrionalis collected from the Yellow Sea. 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](72)
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To investigate the expression patterns of genes involved in TGF-β/Smad signaling pathway responds to photoperiods in zebrafish (Danio rerio) ovary, 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) by using quantitative real-time PCR. The location of p-Smad2 in zebrafish ovary was detected by immunohistochemical. 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](71)
Abstract:
In this paper, the effects of ammonia-N (NH4-N) stress on the activities of lysozgme and 3 digestive enzymes of Babylonia areolatawere studied to reveal the physiological changes. The results show that both the concentrations and treatment time of NH4-N have a significant effect on the activity of digestive enzymes of B. areolata (P&lt;0.05). Compared with the control groups: (1) As the treatment time of NH4-N increasing, the lysozyme generally demonstrates an " suppression-induction” activity. (2) The lower concentration of NH4-N (22 mg·L–1) show a tendency of " induction- suppression” to the pepsin activity of the treated individuals, while other concentrations generally show a "suppression-induction" trend. (3) The lipase activities of B. areolata are generally suppression or similar to the control group with the prolongation of treatment time. (4) The NH4-N treatment time significantly affect the amylase activity, but in the case of a short treatment time the activity of treatment groups do not have much induction or suppression. In conclusion, the stress of ammonia-N could influence the activities of these four digestive enzymes of B. areolata.
[Abstract](108)
Abstract:
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). The open reading frame (ORF) of ToElovl4-like 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. Yeast heterologous expression analysis indicates that ToElovl4-like could extend 18:2n-6 and 20:5n-3 to 20:2n-6 and 22:5n-3, respectively. 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](72)
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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 PmPellinoconsisted of 1 961 bp with an 89 bp 5ʹUTR, a 573 bp 3ʹUTR 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&lt;0.01), but it was inhibited in gill (P&lt;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 may play an important role in the immunity of P. monodon.