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Brief introduction
Journal: Journal of Guangdong Ocean University
Date of First Issue: 1975
Responsible Institution: Department of Education of Guangdong Province
Sponsor: Guangdong Ocean University
Publication frequency: Bimonthly
Phone: 0759-2396013, 0759-2396035
Email: gdouj@vip.163.com; gdouj@gdou.edu.cn
CN: 44-1635/N
ISSN: 1673-9159
Editors: LIU Fei, 17875197989 ; LIU Qingying, 18902504696; LIU Ling, 13828286627; ZENG Ting, 13476012662
Effects of Bacillus subtilis on Growth Performance, Serum Biochemical Indices, Antioxidant Capacity and Lipid Metabolism of Juvenile Tilapia
ZHANG Qin;LIU Dongsheng;ZHOU Jiang;XU Canshuo;HU Yijun;REN Jianhang;ZHANG Ziqi;TONG Tong;LIU Yongqiang;【Objective】 To investigate the mechanism by which dietary supplementation with Bacillus subtilis improves the health of Nile tilapia(Oreochromis niloticus). 【Method】 Juvenile GIFT tilapia with an initial body mass of(16.17 ± 1.32) g were used as experimental subjects. Six iso-nitrogenous and iso-lipidic experimental diets were formulated. The basal diet served as the control group(0 CFU/kg supplementation), while the other five experimental diets were supplemented with Bacillus subtilis at doses of 1 × 107, 1 × 108, 1 × 109, 1 × 1010, and 1 × 1011CFU/kg, respectively. After 60 days of feeding, growth performance, digestive enzyme activities, serum biochemical indices, antioxidant enzyme activities, and the expression levels of lipid metabolism-related genes were determined in each group. 【Result】 Compared with the control group, the mass gain rate, specific growth rate, and daily growth index of tilapia in all groups were significantly increased(P < 0.05), while the feed conversion ratio was significantly decreased(P < 0.05). The activities of intestinal trypsin, lipase, and amylase were significantly enhanced(P < 0.05). The activities of superoxide dismutase, catalase, glutathione peroxidase, and total antioxidant capacity in serum and liver were significantly increased(P < 0.05), while the malondialdehyde content was significantly decreased(P < 0.05). The contents(activities) of low-density lipoprotein, triglyceride, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase were significantly decreased(P < 0.05), while glucose and high-density lipoprotein contents were significantly increased(P < 0.05). Among lipid metabolism-related genes, the expression levels of peroxisome proliferator-activated receptor α, peroxisome proliferator-activated receptor β, acetyl-CoA carboxylase, mammalian target of rapamycin, stearoyl-CoA desaturase, carnitine palmitoyl transferase, adenosine monophosphate-activated protein kinase, phosphatidylinositol 3-kinase, protein kinase B, and peroxisome proliferator-activated receptor gamma coactivator 1α were significantly up-regulated(P < 0.05), while the expression levels of peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein, fatty acid synthase, hormone-sensitive lipase, glucose-6-phosphate dehydrogenase, ribosomal protein S6 kinase, and lipoprotein lipase were significantly down-regulated(P < 0.05). 【Conclusion】 Dietary supplementation with B. subtilis can significantly improve the growth performance of juvenile GIFT Tilapia by enhancing digestive enzyme activities, strengthening antioxidant capacity, and regulating the expression of lipid metabolism-related genes. The optimal supplementation dose was 1×109 CFU/kg, which could be used as a green feed additive in healthy tilapia aquaculture.
Antibacterial Activity of Lavender Essential Oil Against Aeromonas hydrophila and Its Effects on Immunity in a Zebrafish Model
ZHANG Qin;LI Luoqing;DONG Jiancai;HU Yijun;LI Lan;REN Jianhang;LIU Yunpeng;TONG Tong;LIU Yongqiang;【Objective】 This study aims to evaluate the antibacterial activity of lavender(Lavandula angustifolia Mill.) essential oil against a highly virulent bacterium, Aeromonas hydrophila, isolated from the intestine of red claw crayfish(Cherax quadricarinatus), and to assess safety and immunoprotective effects of the essential oil in a zebrafish(Danio rerio) infection model, thereby providing a theoretical basis for developing natural and eco-friendly disease control strategies in aquaculture. 【Methods】 Strain 171215-1 was isolated on thiosulfate–citrate–bile salts–sucrose(TCBS) agar medium, and identified based on morphological features, physiological and biochemical characteristics, and 16S rDNA phylogenetic analysis. The antibacterial activity of lavender essential oil was determined using the Oxford cup method, disk diffusion assay, and broth microdilution to obtain the minimum inhibitory concentration(MIC), and the expression changes of virulence genes were analyzed by quantitative real-time PCR(RT-qPCR). Using zebrafish as a model, the effects of different doses of lavender essential oil on post-challenge survival, antioxidant indices, and the expression of antioxidant-and immune-related genes, including sod, cat, and gsh-px, were evaluated. 【Results】 Based on morphological, physiological and biochemical characteristics, and 16S rDNA phylogenetic analysis, strain 171215-1 was identified as Aeromonas hydrophila and exhibited resistance to multiple classes of antibiotics. In the pathogenicity test, intraperitoneal injection with 1.5 × 10 6 CFU/mL A. hydrophila 171215-1 resulted in a cumulative mortality of(38.33 ± 1.44) %, whereas the 0.5 × 107 and 1.5 × 10 7 CFU/mL groups reached 100% mortality within 2 days. Lavender essential oil exhibited dose-dependent antibacterial activity against this strain, with a MIC of 0.5 mg/mL; in the Oxford cup assay, the diameter of the inhibition zone increased significantly from(14.42 ± 0.82) mm to(40.12 ± 0.58) mm as the sample volume increased from 20 μL to 100 μL. At sub-inhibitory concentrations 0.002 5%、0.005 0% and 0.010 0%, the relative expression levels of the virulence-related genes hlyA, aerA, ahyB, and ompA were significantly reduced by approximately 30%-65%(P < 0.05). In the safety test, dietary supplementation with lavender essential oil resulted in overall low mortality across treatments, with a mortality rate of 0.83% at dietary inclusion levels of ≤ 0.010%. In the infection model, fish fed with a diet containing lavender essential oil at a mass fraction of 0.005% achieved a survival rate of 100.0%, which was significantly higher than that of the positive control(68.89 ± 0.96)%(P < 0.05). Moreover, compared with the positive control, this treatment increased hepatic antioxidant enzyme activities and total antioxidant capacity by approximately 20% to 150%, reduced malondialdehyde levels by approximately 30% to 45%, and significantly downregulated the expression of inflammation-related genes by approximately 3% to 50%(P < 0.05). 【Conclusion】 Lavender essential oil can inhibit multidrug-resistant A. hydrophila in vitro and suppress the expression of key virulence genes. In vivo, it enhanced antioxidant defenses and alleviated inflammatory responses, thereby improving zebrafish resistance to infection. An integrated assessment indicated that the optimal dietary inclusion level of the essential oil is 0.005%.
Antioxidant and Transcriptional Control Mechanisms of Organic Selenium in Alleviating Heat Stress-induced Liver Injury in Huso dauricus
CHE Hongrui;WANG Ruoyu;ZHANG Ying;LI Yutao;【Objective】 To investigate the molecular mechanisms by which organic selenium alleviates hepatic damage induced by thermal stress in Huso dauricus, providing theoretical basis for nutrition regulation strategy against heat stress in sub-cold water fish. 【Method】 Four experiment groups, such as control group(C, 18 ℃), heat stress group(R, 28 ℃), organic selenium group(S, 18 ℃ + 5 mg/kg Se), and heat stress+organic Se group(RS, 28 ℃ + 5 mg/kg Se). After 28 days of feeding, the growth performance indicators were determined, and liver tissue was collected for antioxidant parameters measurement and transcriptome sequencing using Illumina HiSeq 2500 platform. Subsequently, GO and KEGG databases were used for the function enrichment analysis of differentially expressed genes(DEGs), and the relative expression levels of critical candidate genes were validated by qRT-PCR. 【Results】 High temperature stress significantly inhibited the growth of juvenile H. dauricus, with the specific growth rate(SGR) in group R decreasing by 32.4% compared to group C(P < 0.05). After mitigation with organic selenium, the SGR in group RS recovered to 86.6% of the control. Hepatic antioxidant parameters showed that group RS exhibited the lowest MDA molarity [(4.21 ± 7.41) nmol/mg] and the highest SOD activity [(12.31 ± 2.14) U/mg], confirming the antioxidant protective effect of organic selenium at physiological level. A total of 8 715 DEGs were identified in the R vs C comparison, with 58.2% being downregulated. Function enrichment analysis showed that thermal stress significantly activated immune response, heat shock response, and inflammation-related pathways(AGE-RAGE, p53, and PI3K-Akt signaling pathways), while suppressing energy metabolism-related pathways(pyrimidine metabolism, lipid metabolism, etc.). In the S vs C comparison, 485 DEGs were detected, primarily enriched in cell cycle regulation, DNA repair, and glutathione metabolism pathways. qRT-PCR validation demonstrated that organic selenium significantly down-regulated the heat stress-induced hsp90 and ptenb gene expression levels(P < 0.05); furthermore, the expression levels of mtor, ccnd1, tsc2, and ptenb genes in the RS group were significantly further down-regulated compared to group R, indicating a synergistic suppressive effect of organic selenium and heat stress on the PI3K-Akt-mTOR pathway. 【Conclusion】 Thermal stress causes hepatic damage in H. dauricus by inducing transcriptional reprogramming and metabolic disorders. In contrast, organic selenium effectively alleviated heat stress-induced liver injury at both physiological and molecular levels by enhancing antioxidant defense capacity, maintaining protein synthesis homeostasis, promoting DNA repair process, and profoundly suppressing the ptenb gene to regulate the PI3K-Akt-mTOR signaling axis, thereby actively down-regulating energy-consuming anabolic pathways on the basis of antioxidant protection to achieve an adaptive “metabolic throttling–repair priority” regulatory strategy.
Effects of Salinity on Growth,Immune Response,Antioxidant Capacity,and Intestinal Health of Litopenaeus vannamei
HU Naijie;YUAN Hang;CHEN Jian;WANG Hongming;TAN Beiping;ZHANG Shuang;Fisheries College of Guangdong Ocean University;【Objective】 This study aims to systematically evaluate the effects of different salinity conditions on growth performance, disease resistance, nonspecific immunity and antioxidant capacity, as well as intestinal digestive function and gut microbiota structure of Litopenaeus vannamei, providing theoretical support for optimizing salinity management in low-salinity and saline-alkali aquaculture systems for L. vannamei. 【Method】 Juvenile shrimps with initial body mass of(0.38 ± 0.01) g were reared under low(15‰, L), medium(30‰, M), and high(45‰, H) salinity conditions for 8 weeks. Growth performance parameters, including survival rate, mass gain rate, specific growth rate, and feed conversion ratio, were determined. Hepatopancreas and intestinal tissues were collected to analyze nonspecific immune and antioxidant enzyme activities, related gene expression, and intestinal digestive enzyme activities. Gut microbiota composition and function were analyzed based on 16S rRNA high-throughput sequencing. In addition, healthy shrimp were challenged by injection with Vibrio parahaemolyticus(1 × 107 CFU/mL), and the survival was recorded continuously for 72 h. 【Result】 Salinity significantly affected the growth performance of L. vannamei. Compared with the M group, shrimp in the H group showed significantly lower body mass gain and specific growth rates(P < 0.05), while no significant difference was observed between L and M groups(P > 0.05). The survival rate of the H group was significantly higher than those of the L and M groups(P < 0.05). After V. parahaemolyticus infection, the average 72 h survival of the H group was higher than that of the L and M groups, but nonsignificant differences were found among the three groups(P > 0.05). For immune and antioxidant responses, alkaline phosphatase activity was highest in the M group(P < 0.05); acid phosphatase, lysozyme, and phenoloxidase activities also peaked in the M group and were lowest in the L group(P < 0.05). Aspartate aminotransferase activity and gene expression were significantly elevated in the H group(P < 0.05), while alanine aminotransferase activity showed no significant difference(P > 0.05), though its gene expression increased significantly in the H group(P < 0.05). Superoxide dismutase and catalase activities and gene expressions were significantly higher in the M and H groups than those in the L group(P < 0.05), whereas malondialdehyde content showed a decrease-then-increase trend, being lowest in the M group(P < 0.05). Digestive enzyme analysis revealed that intestinal amylase activity and lipase gene expression increased with salinity, reaching the highest levels in the H group(P < 0.05), while trypsin activity and gene expression showed no significant differences among groups(P > 0.05). Microbiota analysis indicated that microbial richness and diversity were significantly higher in the H group compared with the L group(P < 0.05). At the genus level, the relative abundance of Vibrio was significantly lower in the H and L groups than that in the M group(P < 0.05). 【Conclusion】 Salinity modulates the growth and health of L. vannamei by regulating immune-antioxidant status, digestive capacity, and intestinal microbiota structure.
Comparative Transcriptome Analysis of Testis Development across Different Ages in Seriola dumerili
LI Haoyi;DENG Qiuxia;HUANG Yang;RU Xiaoying;YANG Jiahui;LI Guangli;ZHU Chunhua;Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang);【Objective】 This study aims to investigate the molecular mechanisms regulating testicular development in greater amberjack(Seriola dumerili) at different age stages under artificial aquaculture conditions. 【Methods】 Histological observation, transcriptome sequencing analysis, gene functional annotation, and screening and identification of differentially expressed genes(DEGs) were performed on the testis of 1-year-old and 2-year-old greater amberjack. The expression levels of genes related to testicular development were detected using real-time quantitative PCR(qPCR). 【Results】 Histological analysis showed that the testis of 1-year-old fish were at Stage I, while those of 2-year-old fish were at Stage IV. Transcriptome sequencing of testis from 1 and 2 age groups yielded 263 476 570 clean reads, corresponding to 21 258 annotated genes, among which 1 108 were identified as differentially expressed genes(DEGs). Functional enrichment analysis revealed that numerous DEGs were involved in reproduction-related metabolic pathways, including steroid hormone biosynthesis, GnRH signaling pathway, TGF-beta signaling pathway, and Wnt signaling pathway. Both transcriptome data and qPCR results indicated that, compared with 1-year-old fish, 11 genes, namely spata18, spata6, sycp3, smc3, sycp2, mns1, spag17, rsph1, spef2, spa17, and spaca6 were significantly up-regulated in the testis of 2-year-old fish, while 5 genes, namely gsdf, gdf3, and foxl2, cyp19a1a, and bmp8 were significantly down-regulated. 【Conclusion】 Through transcriptome sequencing analysis of testis from 1-year-old and 2-year-old greater amberjack, this study identified age-related differentially expressed genes and meta-bolic pathways involved in testicular development, preliminarily revealing regulation mechanisms of testis development in S. dumerili at the molecular level.
Genetic Diversity and Population Structure of Wild and Cultured Seriola dumerili in the South China Sea Based on Mitochondrial Cyt-b and D-loop Sequences
HE Wanglin;TIAN Changxu;HUANG Yang;DENG Qiuxia;YOU Xinxin;SHI Hongjuan;ZHU Chunhua;【Objective】This study aims to assess the status of genetic diversity in wild greater amberjack(Seriola dumerili) populations in the South China Sea and to quantify the effects of artificial breeding on the genetic structure of the progeny population. 【Methods】Five wild populations(Sanya, Hainan; Huidong, Guangdong; Yangjiang, Guangdong; Zhanjiang, Guangdong; Dongshan, Fujian) and one farmed population were collected from key areas in the South China Sea, comprising a total of 196 individuals. Two mitochondrial molecular markers, the cytochrome b gene(Cyt-b) and the control region(D-loop), combined with bioinformatic analyses were employed to evaluate genetic diversity levels, differentiation patterns, and demographic history. 【Results】60 Cyt-b haplotypes and 104 D-loop haplotypes were identified, respectively. The wild populations in the South China Sea maintain high levels of genetic diversity; specifically, the D-loop haplotype diversity(Hd) of the Huidong and Zhanjiang populations exceeded 0.98. In contrast, the cultured population exhibited a distinct decline in genetic diversity, with Hd decreasing to 0.785, and its nucleotide diversity(π) was significantly lower than that of wild populations. Among 6 populations, there was mild genetic differentiation(the FST = 0.039, and P < 0.001), which mainly originated from the difference between the cultured population and the wild population. Furthermore, the haplotype network displayed a typical star-like topology, which, combined with neutrality tests and mismatch distribution analysis, revealed that the species underwent a rapid population expansion during the Late Pleistocene. 【Conclusion】The wild populations of greater amberjack in the South China Sea possess rich genetic diversity with no significant genetic differentiation among 5 populations, indicating frequent gene flow within the region and making it an natural germplasm reservoir. Although artificial breeding has not yet resulted in a precipitous decline in genetic diversity level, it has induced a significant deviation in the genetic structure of the cultured population and a shift in dominant haplotypes. In future breeding practices, it is recommended to monitor parental contribution rates to maintain genetic balance and to prioritize the introduction of wild individuals with high genetic diversity for germplasm rejuvenation, thereby preventing inbreeding depression.
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Effects of Replacing Fish Meal with Wet Fermented Soybean Meal on Growth, Serum Biochemistry, Digestion, and Immune Antioxidation of Micropterus salmoides
HUANG Xuanyu;HUANG Wen;HUANG Minwei;RUAN Zhuohao;SUN Yuping;WANG Pengfei;Zhang Yehui;HUANG Min;CHEN Xiaoying;【Objective】 To evaluate the effects of replacing fish meal with wet fermented soybean(WFSBE, produced using bacteria and enzymes) in the diets of juvenile largemouth bass(Micropterus salmoides), and to provide a reference for the application of fermented plant proteins in largemouth bass feed. 【Method】 Four isonitrogenous and isolipidic diets were formulated by replacing fish meal with WFSBE at 0%(control), 10%, 20%, and 30%(all replacement levels expressed as mass fractions), designated as T0, SF10, SF20, and SF30, respectively. Juvenile largemouth bass with an initial body mass of(8.49 ± 0.01) g were fed these diets for 8 weeks. Lysine and methionine were supplemented in the SF20 and SF30 groups. Growth performance, body composition, serum biochemical parameters, digestive enzyme activities, immune and antioxidant indices were measured. 【Results】When the fish meal replacement level was ≤20%, there were no significant differences(P > 0.05) in final mean body mass, body mass gain rate, or feed conversion ratio compared with those in the T0 group. However, at 30% replacement, growth performance significantly decreased and feed conversion ratio significantly increased(P < 0.05). There were no significant differences(P > 0.05) among groups in morphological indices, whole-body crude protein, calcium and phosphorus content. Whole-body crude lipid content in the replacement groups decreased compared to that in T0, with SF10 and SF30 groups significantly lower than T0 group(P < 0.05). Serum triglyceride levels in each replacement group were significantly lower than those in T0 group(P < 0.05). Hepatic lipase activity in SF10 and SF30 groups was significantly lower than that in T0 group(P < 0.05). Hepatic amylase activity in SF20 was significantly higher than that in SF30(P < 0.05), but not significantly different from T0 group(P > 0.05). Gastric protease activity in SF10 and SF30 groups was significantly higher than that in T0 group(P < 0.05), while gastric amylase activity in SF30 was significantly lower than in T0 that(P < 0.05). There were no significant differences(P > 0.05) in serum antioxidant indices between replacement groups and T0 group. However, hepatic superoxide dismutase(T-SOD) activity in all replacement groups was significantly lower than that in T0 group(P < 0.05), while hepatic malondialdehyde(MDA) content and total antioxidant capacity(T-AOC) were significantly higher(P < 0.05). Intestinal MDA content in SF20 group was significantly lower than that in T0 group(P < 0.05). Gastric T-SOD activity in SF20 group was significantly higher than in T0 and SF30 groups(P < 0.05). The average gastric MDA content in all replacement groups was lower than that in T0 group, with SF30 group significantly lower(P < 0.05). Other gastrointestinal antioxidant indices in each replacement group showed no significant differences compared to those in T0 group(P > 0.05).【Conclusion】 From the perspective of growth performance, WFSBE can partially replace fish meal in the diet of juvenile largemouth bass; however, the replacement level should be controlled within 20%. When the replacement level reaches 30%, it will have adverse effects on the growth and feed utilization of juvenile largemouth bass.
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Immunogenicity of Inactivated Tissue Homogenate Against Carp Edema Virus
CAI Weilin;ZHU Jinghua;YU Hong;SUN Xueliang;FANG Zhenzhen;SHI Hongyue;YANG Xiaohan;CHEN Chengxun;ZHANG Zhen;【Objective】 This study aims to evaluate the immunoprotective efficacy of an inactivated tissue homogenate of carp edema virus(CEV) as a vaccine in koi carp(Cyprinus carpio) and elucidate the immune mechanisms it triggers, providing a reference for the research of carp edema disease vaccine. 【Methods】 Koi were divided into an immunized group, and negative and positive control groups. The immunized group received an intraperitoneal injection of CEV-inactivated tissue homogenate, whereas the control groups received an equal volume of physiological saline. Serum, liver, spleen and gill samples were collected at regular intervals for 21 days post-immunization. Serum antibody levels(IL-6, IFN-α, IgM, TNF-α) were quantified by ELISA; hepatic antioxidant enzyme activities(SOD, CAT, GSH-PX, T-AOC) and malondialdehyde(MDA) content, as well as splenic immune enzyme activities(LZM, NO, AKP, ACP), were measured using commercial kits. Expression of immune-related genes(C3, IFN-α, IgM, IL-6, TNF-α) in spleen and gill were analyzed by real-time quantitative PCR. After immunization, fish were challenged with CEV, and viral load, cumulative mortality and histopathological changes in gill, liver and kidney were monitored. 【Results】 In terms of serum antibody levels, IL-6, IFN-α, and TNF-α in the immunized group were significantly higher than those in the negative control group from 6 h to 21 d, while IgM levels were significantly increased from 3 to 21 d(P < 0.05). Regarding immune enzyme activities, the activities of superoxide dismutase(SOD, at 6 h, 1 and 21 d), catalase(CAT, at 1 d and 7 to 21 d), glutathione peroxidase(GSH-Px, at 6 h and 3 to 21 d), and total antioxidant capacity(T-AOC, at 1 to 21 d) in the liver were significantly enhanced at multiple time points(P < 0.05), with T-AOC reaching its peak at 14 dpi. Malondialdehyde(MDA) showed an initial increase followed by a decrease, and was significantly higher than that in the negative control group(P < 0.05). Lysozyme(LZM) activity in the spleen was significantly elevated from 1 to 14 d(P < 0.05), peaking at 14 d. Nitric oxide(NO) content was significantly increased from 7 to 21 d(P < 0.05). Alkaline phosphatase(AKP) activity was significantly elevated at 6 hours, and acid phosphatase(ACP) activity was enhanced at 6 h, 14 and 21 d(P < 0.05). At the gene expression level, IL-6 in the spleen peaked at 3 d, and IgM was significantly upregulated at 1 to 3 d and 21 d. INF-α was significantly upregulated after 3 d, and peaked at 14 d, while TNF-α was significantly elevated at 6 h, 1 d, 14 d, and 21 d. Complement C3 was significantly increased at 7 and 21 d. In gill tissue, IL-6 and TNF-α were continuously and significantly elevated from 7 to 21 d. INF-α and complement C3 were significantly upregulated at 7 to 21 d, peaking at 21 d, and IgM was significantly increased at 1 and 21 d. After challenge, viral loads in gill of the immunized group were highly lower than those of the challenged control group with 22.43 copies/ng at 7 d and 14.33 copies/ng at 14 d(P<0.05). Cumulative mortality in the immunized group was 0%, whereas it reached 43.33% in the challenged controls. The histopathological results showed that severe swelling, degeneration and necrosis were observed in gill, liver and kidney of the viruschallenged positive control, whereas the immunized and challenged fish exhibited only mild, reversible lesions with largely intact tissue architecture. 【Conclusion】 The CEV-inactivated tissue homogenate effectively activates humoral immunity of koi, enhances antioxidant and non-specific immune capacity, and up-regulates key immune genes in multiple organs, thereby markedly suppressing viral replication and alleviating tissue damage. This inactivated preparation shows significant protective efficacy against carp edema virus disease and holds promise for practical application.
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Effects of Slightly Acidic Electrolyzed Water Combined with Ultrasonic Sterilization on Actin Structure of Tuna Meat
SUN Xiejun;LIU Xiaofang;LI Xiuxia;WANG Zhen;LI Jianrong;【Objective】 To study the effect of slightly acidic electrolyzed water and ultrasonic sterilization on the actin structure and cathepsin activity of Thunnus obesus during storage at 0 ℃, and the effect of cathepsin B on its actin degradation was further explored. 【Methods】 Untreated tuna was used as control, the tuna was sterilized with 55 mg/mL slightly acidic electrolytic water and 280 W ultrasonic treatment for 5 min. The changes of actin structure and related cathepsin activity of the refrigerated fish meat were analyzed by Differential Scanning Calorimetry(DSC), Fourier Transform Infrared Spectroscopy(FTIR), and endogenous fluorescence spectroscopy. Combined with the activities of cathepsins B, L, and D and molecular docking techniques, the changes in myosin structure and related cathepsin activities in tuna meat during storage at 0 ℃ after sterilization were investigated.【Results】 The electrophoretic bands of actin in control group were shallower, the decrease rate of enthalpy of denaturation in the treatment group was lower than that in the control group, α-helix decreased by 69.09% in the control group and 41.33% in the experimental group. The stability of tryptophan residues in the treatment group was higher. Molecular docking showed that the polar solvation energy of actin-cathepsin B could reach-2 179.70 kJ/mol, and the hydrogen bond between the two was more frequent. 【Conclusion】 Actin in the treatment group has better thermal stability and can better protect the secondary and tertiary structure of actin. Cathepsin B plays a key role in the degradation of actin in fish. The driving force of the binding of actin and cathepsin B is polar solvation energy, and hydrogen bond plays a major role in the binding of both. The study can provide a theoretical reference for the application of weakly acidic electrolytic water in tuna storage and freshkeeping.
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Effect of Different Oxides in Natural Clay on the Pyrolysis of Spirulina
LIU Kai;XU Qing;SU Yingchen;【Objective】To investigate the effect of common oxides (Al_2O3,MgO,and SiO2) in clay on the pyrolysis behavior of Spirulina.【Method】Thermogravimetric analysis (TGA) and fast pyrolysis combined with gas chromatography-mass spectrometry (GC-MS) were used to analyze the pyrolysis process and products of Spirulina.The catalytic effects of the oxides were evaluated using the FlynmWall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) kinetic models.The differences in pyrolysis temperature,residue mass,and product composition with and without the addition of oxides were compared.【Results】The introduction of oxides expanded the pyrolysis temperature range of Spirulina.SiO2 increased the yield of coke.MgO,as an alkaline catalyst,significantly inhibited the formation of acidic compounds in the pyrolysis oil,reducing their yield from 23.49%to 10.66%.MgOexhibited the strongest catalytic effect on Spirulina pyrolysis.The catalytic effectiveness followed the order:MgO>Al_2O3>SiO2.Kinetic analysis showed that after the addition of oxides,the average activation energy of Spirulina pyrolysis decreased from 207.84 kJ/mol to 196.88 kJ/mol (Al_2O3),188.23kJ/mol (MgO),and 205.77 kJ/mol (SiO2).【Conclusion】This study demonstrates that clay oxides significantly influence the distribution of pyrolysis products and energy consumption in Spirulina pyrolysis.Al_2O3 and MgO exhibit notable catalytic effects,while SiO2 primarily serves as a heat transfer medium.This provides important theoretical support for the high-value pyrolysis of Spirulina.
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Several Main Calculating Equations of Properties Parameter of LiBr-H_2O
Jia Mingsheng (Engineering College of Zhanjiang Ocean University, Zhanjiang, Guangdong, 524025)In this paper, the author makes regressive analysis of the practical data of LiBr H 2O's properties and puts forward balanced equation of LiBr H 2O and calculating equations of properties parameter about viscosity, crystalline temperature, density, specific heat at constant pressure and enthalpy, etc. The equation in regressive and inductive method has high precision and it can meet the demands of thermodynamic calculation and heat transfer calculation for two stage LiBr H 2O absorption refrigeration cycle.
The Control of Eutrophic Water in Ponds by Floating-bed Soilless Culture of Plants
Bing Xuwen Chen Jiachang (Freshwater Fisheries Research Center of Chinese Academy of Fishery Sciences, Wuxi Jiangsu 214081)The control of eutrophic water in ponds were tested by culturing landscape plant canna ( Cana generalis Bailey) on soilless floating beds. The results indicated that the coverage of the landscape plant correlated positively with the removal rates of nitrogen and phosphorus in pond water, and increase of the coverage rate of the landscape plant could increase removal rate, conductivity and chlorophyll a also significantly decreased. Results showed that water quality of eutrophic ponds was improved significantly. In eutrophic ponds , the 20% coverage of the landscape plant would be the best.
Effect of Heat Stress on Biochemical Indices in Serum and Endocrinic Function of Broilers
Liu You ;Lin Hongying; Luo Dongjun;The effect of heatstress on broilers was studied in this paper by determining theperformance,biochemical and endocrinic indices in serum The result shows that,a fewindices suchas, the body weight,feed conversion ratio,average daily weight gain, the serum protern,albumin,calcium,phosphorus and thyroxine (T3T4) were all declined significantly (P<0. 05 or P<0.01 ) in the experimental group at 30 and 50 days old. The concentration of serum potassiumdeclined significanty only in 30 days, but the concentration of serum urea nitrogen, chlorine,cortisol and the activity of lactic dehydrogense,creatine phosphokinase of serum sodium,glucosewere not affected by heat stress.
Compendium of Folk Narration
Dong Naibin Cheng Qiang (College of Literature, Shanghai University, Shanghai, 200031, China)Folk narration refers to the oral narrative activities, of common people living in the bottom of the society, mainly their artistic narration. Along with the basic character of oral forms, they have the characters of flexibility, vaporization, anonymous having regional and historical texts by deletion, vivid forms and contents which cater for the public mentality, thoughts and interests, combining real facts with fantasy, as well as contradicting and compromising main stream of culture. Folk narration exists not only in the folk tales, but also in the literary texts by the letters, which reinforce the oral forms into the written forms and then into the classics. The classic texts become the new source of folk narration, which is considered as the foundation of it.
Research Survey of Chi Li's Novels in the Past Ten Years
YE Lan-tao(Literature college of Guangdong Ocean University,Zhanjiang,Guangdong,524088)Chi Li's novels as important representative texts of Chinese contemporary literature caused a lot of research and comments.These comments attempted to explain various kinds of meanings of Chi Li's novels from the following four respects.: First,awakening of woman's consciousness.Second,all boring and helpless life viewpoints.Third,internal and external comparison of themes and structures.Forth,survey and review.This paper attempts to perfect and strengthen the knowledge of Chi Li's novels through summarizing the state in the past ten years.
On the Symbolism of Xue Baocai and Lin Daiyu
WANG Qin(Yangjiang Vocational and Technological College,Yangjiang 529500,China)Xue Baocai and Lin Daiyu were two main characters in A Dream in Red Mansions.Xue Baocai embodied the Confucianist thoughts of cultivating oneself and maintaining family harmony while Lin Daiyu embodied the Taoist thoughts of moral quality of independence.The thoughts of these two heroines were the reflection of the social life and natural life of the urban and rurat class.In this article,the author tries to explore the symbolism embodied by these two characters by analyzing the images of these two characters.
Research on Characters in The Book of Poetry in Recent Thirty Years
CHEN Li;ZHU Li-hui;It summed up the achievements of characterization in The Book of Poetry from four parts:image analysis, artistry, the cause of characteristics and moral implication in the past 30 years. The appearance and excellent qualities were described in the analysis on the female. Meanwhile, moral characters were described in the analysis about the male. The artistic techniques were always expressed by Fu, Bi, Xing and the general technique of character description. The cause of the characteristics might be the religious consciousness, aesthetic tradition and social background. The moral implication included such moral consciousness as filial piety and fraternal duty, integrity, loyalty and patriotism. The limitations of the study were the repeating analyses on characterization, lacking of deeper digging in artistic techniques and realistic significance about moral implication.
Several Main Calculating Equations of Properties Parameter of LiBr-H_2O
Jia Mingsheng (Engineering College of Zhanjiang Ocean University, Zhanjiang, Guangdong, 524025)In this paper, the author makes regressive analysis of the practical data of LiBr H 2O's properties and puts forward balanced equation of LiBr H 2O and calculating equations of properties parameter about viscosity, crystalline temperature, density, specific heat at constant pressure and enthalpy, etc. The equation in regressive and inductive method has high precision and it can meet the demands of thermodynamic calculation and heat transfer calculation for two stage LiBr H 2O absorption refrigeration cycle.
Simulation of CDMA Communication System Based on MATLAB
ZHANG Pei-zhen,ZHANG Jian-lan(1.School of Information,Guangdong Ocean University,Zhanjiang 524088,China)This paper makes use of the SIMULINK simulation function of the MATLAB platform to carry out the modeling,simulation,and analysis of the integrated CDMA wireless communication system.At the same time,the important links of communication system are introduced in detail,including spread spectrum,error control coding and decoding,modulation technology and channel,etc.This simulation platform displays the communicative operation mode and superiority of CDMA effectively.