Latest Articles

Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
Display Method:
Cloning and transcriptional regulation of slitrk3 gene promoter in large yellow croaker (Larimichthys crocea)
ZHOU Ruitao, YUE Zhufeng, JI Jiaojun, WEN Jing, JIANG Dan, WANG Zhiyong, FANG Ming
, Available online  , doi: 10.12131/20220309
Slitrk3, a neurosynaptic-related protein, can regulate the development of inhibitory synapses. To explore the transcriptional regulation mechanism of slitrk3 gene of the large yellow croaker (Larimichthys crocea) can provide a new idea for solving the problems of growth, stress and anti-stress in the L. crocea culture. We conducted a multiple sequence alignment and a phylogenetic tree analysis of amino acids for Slitrk3 in L. crocea and other species to investigate the transcriptional regulation mechanism of the neural cell adhesion molecule for slitrk3 gene. Besides, we predicted the potential core promoter regions, CpG islands and transcription factor binding sites of slitrk3 gene by bioinformatics methods, and detected the Luciferase activity of promoter of slitrk3 gene by the Dual-Luciferase Reporter System. Bioinformatics analysis shows that the amino acid sequences of Slitrk3 were highly conserved in fish. There were two transcription start sites, two CpG islands, and multiple transcription factor binding sites such as Sp1, GR, C/EBPα and C/EBPβ in promoter of slitrk3 gene. Dual-Luciferase Reporter System shows that the regions from −1970 to −1614 bp and from −1 210 to −667 bp contained positive regulatory elements; while the regions from −1614 to −1210 bp, from −667 to −376 bp and from −376 to −147 contained negative regulatory elements; and the regions from −147 to +16 bp might be core promoter of slitrk3 gene. The results lay a theoretical foundation for the further study of transcriptional regulation mechanism of slitrk3 gene in L. crocea.
Spatial-temporal changes in western and central Pacific warm pool and their impact on distribution of Katsuwonus pelamis
LIN Hongyu, WANG Jintao, CHEN Xinjun, JIANG Mingfeng, XU Zi'an, LEI Lin, LYU Zehua
, Available online  , doi: 10.12131/20220235
The western and central Pacific tropical waters are largest fishing ground for the skipjack tuna (Katsuwonus pelamis) in the world. To rationalize the development and utilization of the fishery resources of K. pelamis free-swimming school fishery in the Western and Central Pacific Ocean, we derived the gravity center by calculating the resource abundance index based on the data of for skipjack tuna from 1995 to 2019 from the Western and Central Pacific Fisheries Commission. Besides, we conducted a Pearson correlation analysis by combining sea surface temperature (SST) and Oceanic Niño Index (ONI). The results show that the catch per unit effort (CPUE), which can be used to characterize the resource abundance of the gravity center of free swimming school of skipjack, was significantly correlated with the longitude of the gravity center of the warm pool and the longitude of the right edge. The relative positions and trends of the CPUE and warm pool indicators (Longitude of the gravity center of the warm pool and longitude of the right edge) were different under different climate modes but were the same under the same climate mode. The results show that the changes in the gravity center of the fishing grounds can be predicted by the warm pool's changes in the gravity center. By constructing the spatial-temporal distribution relationship between the warm pool field and the resource abundance, we found that the right edge of the warm pool could be associated with the spatial distribution of the free swimming school of skipjack, which provides an indication of the fishing ground boundary of free-swimming school stock in commercial fishing purse-seine skipjack tuna, and provides a scientific basis for its resource exploitation and conservation.
Evaluation of gel properties of heat-induced surimi of Ictalurus punctatus from four genealogies
WANG Xin, LI Mengzhe, ZHANG Wei, KONG Yunfei, XIONG Zhiyu, SHI Tong, BAO Yulong, YUAN Li, ZHANG Shiyong, WANG Minghua, CHEN Xiaohui, GAO Ruichang
, Available online  , doi: 10.12131/20220198
Ictalurus punctatus has less fishbones and more meat, very suitable for being processed into surimi products. In order to evaluate the processing characteristics of surimi of I. punctatus from different genealogies, we selected the dorsal muscle of the four genealogies of "Jiangfeng No.1" I. punctatus (DZ1-1, KB4-1, K2-1, 46-1) which were prepared into surimi after rinsing, chopping, dewatering and refined filtration, and heated them at two stages to make heat-induced surimi gels. By measuring the thermal stability of surimi protein, physical and chemical properties of the surimi gels, such as whiteness, texture, water holding capacity and gel strength, we analyzed the heat-induced gels of I. punctatus from different genealogies. The results show that compared with the other genealogies, the surimi myofibrillar protein of DZ1-1 genealogy had higher thermal stability, and the relative content of β-folding and β-turning structure was higher, which affected the gel quality of heat-induced surimi. There are no significant differences in the whiteness of heat induced surimi gels prepared by different genealogies of I. punctatus, with water holding capacity over 80%. The gel strength of the DZ1-1 genealogy was 2.7×102 g∙cm, which was better than other genealogies, while the hardness, springiness and gumminess of the DZ1-1 genealogy were not different from the KB4-1 genealogy, but significantly better than the other two genealogies. In conclusion, the DZ1-1 genealogy is more suitable for surimi processing.
Analysis on differences of microbial community structure and main flavor substances of Cyprinus carpio var. Jinbei cultured in paddy fields and ponds
YU Meijuan, YANG Hui, YU Changsheng, CAI Jiaoming, BU Zilong, ZENG Xianwen
, Available online  , doi: 10.12131/20220270
It is important to study the differences of intestinal flora and fish flavor quality of Cyprinus carpio var. Jinbei under different culture modes for its breeding optimization. We applied illumina high-throughput sequencing technology to analyze intestinal microflora of C. carpio var. Jinbei cultured in paddy fields (FGF) and ponds (FGP), respectively. Besides, we used liquid chromatography (LC) to determine the flavor substances, and used headspace solid phase microextraction combining with gas chromatography-ion mobility spectrometry (HS-SPME-GC-IMS) to determine the volatile flavor substances. Then we calculated the taste activity value and relative odor activity by combining the sensory threshold. Significant difference analysis shows that Vibrio, Bacteroides, Alteromonadales, Shewanella, Pseudomonas psychrophila and Brevinema were the main bacteria in FGF group, while Moraxella and Klebsiella were the main bacteria in FGP group. The contents of IMP and flavor activity in FGF group (1.676 g·kg−1 and 6.705) were significantly higher than those in FGP group (0.246 g·kg−1 and 0.985). The contents of umami amino acids and sweet amino acids in FGF group (0.143 and 2.052 g·kg−1) were higher than those in FGP group (0.109 and 2.001 g·kg−1). However, the contents of bitter amino acids in FGF group (3.193 g·kg−1) were lower than those in FGP group (3.836 g·kg−1). Moreover, the components of volatile compounds were complex, and the types of key odor compounds (ROAV≥1) and compounds that could modify the overall flavor (0.1≤ROAV<1) were different. The correlation analysis between bacteria genera and flavor substances shows that Vibrio, Bacteroides, Klebsiella and Morganella were significantly correlated with flavor substances (0.01≤P<0.05 & 0.001≤P<0.01 & P<0.001). The results indicate that cultivation mode affects the intestinal microbes of fish, and affects the flavor quality of fish indirectly.
Effects of cold stress-induced dormancy methods on life characteristics and nutritional quality indexes of Patinopecten yessoensis during anhydrous living-preservation
CHANG Xiangyang, JIANG Peihong, DENG Jie, FAN Xiuping, QIN Xiaoming
, Available online  , doi: 10.12131/20220304
Exploring the best method to induce the dormancy of scallops (Patinopecten yessoensis) before live transport can provide a theoretical basis for their survival and circulation. Referring to the actual industrial circulation, we treated the samples by three methods of natural cooling of crush ice, acute continuous cooling and gradient cooling, so as to explore the effects of different cooling and dormancy methods on the survival rate, life characteristics and nutritional quality of scallops during anhydrous living-preservation. The results show that the survival rate of the gradient cooling group was 93.33% after 3 d of keeping alive at 4 ℃, significantly higher than that of the acute and natural cooling groups. In the process of cooling dormancy, regular electrocardiogram could not be detected in the natural and acute cooling groups due to the sudden temperature change, and the heart rate in the gradient cooling group showed a regular slow decline. During the live transport, the heart rate in each group showed a decreasing trend. After 3 d of keeping alive, the irregular heart rate in the natural ice cooling group was no longer observed, while the irregular heart rate in the gradient and acute cooling groups was still observed. The edge mantle retraction ratio and the response time of all three cooling groups tended to increase gradually (Those of natural and acute cooling groups were significantly higher than those of gradient cooling groups), and the heart rate was negatively correlated with the response time of the mantle. The contents of water, crude protein, crude fat and muscle glycogen all showed a decreasing trend, and the consumption of glycogen was the largest. Less loss of nutrients before live transport was observed in the gradient cooling groups compared with the other groups. The microstructure also shows that the closed shell muscles in the gradient cooling group were closely arranged without an obvious fracture. This study indicates that inducing P. yessoensis to enter dormancy or semi-dormancy state by gradient cooling and then keeping them alive without water, is beneficial to improving the survival rate of living P. yessoensis, reducing the loss of nutrients during the live transport, and maintaining the vitality of living P. yessoensis, so it is more conducive to its anhydrous living-preservation.
Enzymatic extraction and physicochemical properties of Porphyra haitanensis protein
LENG Meng, LIN Duanquan, WENG Ling, ZHANG Lingjing, MIAO Song, CAO Minjie, SUN Lechang
, Available online  , doi: 10.12131/20220242
Abalone viscera is rich in hydrolytic enzymes that can decompose algal polysaccharides. In order to realize the highly efficient extraction and industrial production of Porphyra haitanensis protein, we used abalone visceral enzymes to break the cell wall of P. haitanensis to extract porphyra protein, and compared the physicochemical properties in proteins prepared by freeze drying and air drying. The results show that the optimal enzymatic conditions were obtained as follows: enzyme dosage of 7.6%, enzymatic hydrolysis time of 2.8 h, enzymatic hydrolysis temperature of 35 ℃, and material-to-liquid ratio of 1:25. The protein yield under above conditions was (238.65±2.13) mg∙g−1. The results of appearance morphology and cell morphology of Porphyra haitanensis indicate that abalone viscera enzymatic digestion could break down the cell wall of P. haitanensis significantly. Freeze-dried P. haitanensis protein (FPP) showed better solubility and emulsification properties than spray-dried P. haitanensis protein (SPP) at different pHs (P<0.01), while the surface hydrophobicity and contact angle of SPP were higher than those of FPP (P<0.01). Scanning electron microscopy shows that FPP had a smooth lamellar surface, while SPP had a more uniform spherical particle size with grooves on the surface. In conclusion, the abalone viscera enzyme was effective in breaking down the cell wall of P. haitanensis and leaching out the water-soluble proteins. All the prepared proteins had good physicochemical properties, while the freeze-dried proteins are better than air-dried proteins.
Extraction process of intestinal lipid droplets and lipid droplet-related proteins from tilapia
LI Jie, HUANG Hui, XIANG Huan, CEN Jianwei, WEI Ya, ZHAO Yongqiang, HAO Shuxian, LI Laihao
, Available online  , doi: 10.12131/20220285
Lipids in animals and plants exist in the form of lipid droplet (LD). It is very important to master the purification methods of lipid droplet and lipid droplet related protein (LDRP) for understanding the lipid changes and influence mechanisms of fish, and seeking appropriate regulatory approaches. In this paper, the lipid droplet and LDRP were separated and purified through centrifugation, resuspension and solubilization by using Oreochromis niloticus intestinal tissues as raw material. The results show that the intestinal adipose tissues were effectively removed by three times of centrifugation and three times of resuspension to obtain the pure lipid droplet. Although the concentration of LDRP protein extracted by solubilization was higher, the electrophoretic bands showed an obvious trailing phenomenon, indicating that the effect of lipid removal was poor, which affected the purity of LDRP extraction. Delipidation and solubilization need to be combined with four groups of organic solvents to obtain the LDRP extracted samples with high purity and good re-solubilization effects. The effects of centrifugation drying method and lipid droplet freezing on LDRP solubilization were not significantly different.
Effect of alginate oligosaccharides combined with low magnetic field freezing on structure and properties of myofibrillar protein of silver carp
CONG Haihua, LU Xiaoyan, ZHOU Qian, ZHANG Ziwei, ZHENG Zhihong, LIU Li, SONG Guanliang, LEI Huiwen, CHEN Jiwei
, Available online  , doi: 10.12131/20220245
In order to obtain good preservation quality in the processing of aquatic pre-made products with silver carp (Hypophthalmichthys molitrix) as raw material, we designed a new freezing method. We investigated the structural and functional changes of myofibrillar protein (MP) by freezing alginate oligosaccharides (AO) at a mass fraction of 0.6% with a low magnetic field (LMF) of 2 mT, and used no treatment at −20 ℃ as the blank group. On this basis, we added AO and AO+LMF as the experimental group, added AO as the common freezing (CF) group at −30 ℃, and had frozen the MP for 28 d. By measuring the solubility, turbidity, surface hydrophobicity, sulfhydryl content, thermal stability, Fourier transform infrared spectroscopy and endogenous fluorescence spectroscopy, we comprehensively compared the structure and properties of frozen MP. The results show that there were no significant differences in the turbidity among the three freezing methods at −20 ℃. The protein solubility of CF group was 94.11%. After AO+LMF treatment, the exposure of hydrophobic groups reduced, with a higher total sulfhydryl content of 15 mmol·kg−1, and the exposure of tryptophan residues reduced, which protected its protein tertiary structure effectively. Fourier transform infrared spectroscopy shows that after AO modification and freezing, MP denaturation was the lowest, α-helix content was higher, and secondary structure was more stable. It it showed that 0.6% fucoidan with low magnetic field freezing treatment can better maintain the stability of MP in silver carp, which lays the foundation for the application of AO in frozen aquatic products and provides references for the further research on the low magnetic field freezing.
Preparation, separation and physicochemical properties of α-glucosidase inhibitory peptides from Miichthys miiuy
HUO Yumei, HU Xiao, WU Yanyan, JIANG Jinjin
, Available online  , doi: 10.12131/20220269
In order to achieve the high-value utilization of processing by-products of Miichthys miiuy, taking α-glucosidase inhibition rate as an index, we carried out a single factor experiment and applied the response surface methodology to optimize the preparation process of α-glucosidase inhibitory peptides from minced fish muscle of M. miiuy processing by-products. The optimal enzymatic hydrolysis conditions with trypsin were as follows: hydrolysis time 4.8 h, enzyme dosage 0.21%, hydrolysis pH 8.5, material-liquid ratio 1∶2 (m/V), hydrolysis temperature 46 ℃. On this basis, we analyzed the inhibitory activity of the enzymatic hydrolysates before and after the simulated gastrointestinal digestion in vitro, and drew the kinetic curve of enzyme inhibition. Then we separated the enzymatic hydrolysate by SephadexG-25 so as to investigate the molecular weight distribution and amino acid composition of the enzymatic hydrolysates. The results show that the α-glucosidase inhibitory rate increased to 61.79% after that the α-glucosidase inhibitory peptide was simulated gastrointestinal digestion in vitro. Its inhibition type on α-glucosidase was mixed type inhibition. The molecular mass of the enzymatic hydrolysate was concentrated below 3 kD, accounting for 91.85%. After the separation by G-25, the α-glucosidase inhibition rate of F4 fraction was 58.05%. In Group F4, 78.28% of peptides were less than 1 kD. The amino acid analysis shows that the enzymatic hydrolysate was rich in Asp, Glu, Arg, Tyr, Val, Ala, Leu and Lys.
Comparative transcriptome analysis in livers of female and male marine medaka (Oryzias melastigma)
ZHANG Linbao, TIAN Fei, CHEN Haigang, ZHANG Zhe, YE Guoling, LI Yitong, TANG Haiwei
, Available online  , doi: 10.12131/20220250
As a gonochoristic model animal, marine medaka (Oryzias melastigma) is good for studying the sex-specific responses of organisms to xenobiotic pollutants. We used comparative transcriptomics technology to systematically investigate the differentially expressed genes (DEGs) between the liver tissues of female and male medaka. We identified 683 significantly up-regulated DEGs in the females, and 668 DEGs in the males. The high expressed DEGs in the females were involved in the reproductive and sex hormone synthesis pathways, such as vitellogenin and estrogen receptor. The top twenty DEGs in the males were involved in energy metabolism, cytoskeleton and muscle contraction, such as pyruvate kinase, creatine kinase, myosin and troponin. Except for the DNA mismatch repair protein, all the 17 DEGs had similar magnitude and expression trends by both qRT-PCR and RNA-seq analyses, which confirms the reliability of the RNA-seq data. The results demonstrate that the gene expression patterns are different in the livers of female and male medaka, and the DEGs provide a theoretical basis for promoting the molecular mechanism of sex-specific responses of medaka to xenobiotic pollutants.
Screening of antagonistic bacteria against visceral white-spots disease of Larimichthys crocea and preliminary study on its biological characteristics
LI Zhangchan, SHI Hui, XU Wenjun, HE Jie, XIE Jianjun, WANG Gengshen, WANG Wei
, Available online  , doi: 10.12131/20220251
In order to achieve the biological prevention and control of visceral white-spots disease of Larimichthys crocea, and promote the reduction of drug use in aquaculture, we isolated and screened the probiotics with an antagonistic effect on Pseudomonas plecoglossicid, which is a pathogen of visceral white spot disease in L. crocea, from the intestine of healthy L. crocea. The strains were screened by agar diffusion method, identified by physiological and biochemical characteristics and molecular biology analysis, and evaluated for hemolysis, drug sensitivity, safety, enzyme production ability and broad-spectrum antibacterial activity. Thirty-seven strains of potential probiotics were isolated and the three most potent strains were further characterized for their probiotic potential, named as P1-17, P2-33 and P3-11. The three most promising isolates were identified by sequencing the 16S rRNA gene and physiological and biochemical characteristics. Strains P1-17 and P2-33 were identified as Bacillus velezensis and P3-11 was identified as Enterococcus faecalis. According to the hemolytic test and disk diffusion method, none of the three strains had sigificant hemolytic rings, containing few drug resistance factors, so they had no potential pathogenicity. The result from the artificial infection safety test confirmed that these three strains of antagonistic bacteria had no pathogenicity to healthy L. crocea. The results of the antimicrobial spectrum show that two strains of Bacillus had an antagonistic effect on common aquatic pathogens such as Vibrio alginolyticus, V. harveyi and Photobacterium damselae. Moreover, two strains of Bacillus could produce amylase and protease, while the strain of E. faecalis only had an antagonistic effect on P. plecoglossicida. The study provides a scientific basis for the subsequent screening and application of intestinal probiotics in L. crocea.
Effect of density on antioxidant and nonspecific immunity of mud crab (Scylla paramamosain)
TIAN Yu, JIE Yukun, ZENG Xiangbing, YUE Yan, LIU Guangxin, CHENG Changhong, MA Hongling, GUO Zhixun
, Available online  , doi: 10.12131/20220312
Density stress has a negative impact on the immune and antioxidant functions of aquatic animals. In order to improve the potential production of mud crab (Scylla paramamosain) and provide a theoretical basis for its aquaculture development, we cultured the mud crabs for 72 h at three different densities: 8 ind·m−2 (Low density group), 16 ind·m−2 (Medium density group), and 32 ind·m−2 (High density group) to study the effects of density on the antioxidant and immune capacity of mud crabs. The results of antioxidant enzyme activity show that the activities of catalase (CAT) and superoxide dismutase (SOD) in the high density group were significantly higher than those in the low density and medium density groups (P<0.05), but there was no significant difference in the glutathione peroxidase (GSH-Px) activity among the groups. Additionally, the malondialdehyde (MDA) content in the high density group was significantly higher than that in the low density and medium density groups. The activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LZM) in the high density group were significantly lower than those in the low density and medium density groups (P<0.05), but there was no significant difference between the medium density group and the low density group. The real-time PCR results indicate that the heat shock protein 70 (HSP70) expression level in the high density group decreased first and then increased, significantly lower than that in low density and medium density groups from 6th hour to 48th hour (P<0.05). The expression level of Caspase 3 in the high density group increased significantly after 6 h and decreased gradually after reaching the maximum level at 24th hour, but was always significantly higher than that in the low density group (P<0.05). In conclusion, high density culture can cause oxidative damage, leading to the decline of immunity of mud crabs. The stock density of 16 ind·m−2 has no significant effects on the antioxidant and immune abilities of mud crabs.
Effect of low temperature stress on antioxidant stress, apoptosis and histological structure of gills in cobia (Rachycentron canadum)
LI Yu, HUANG Jiansheng, CHEN Youming, WEN Zhenwei, OU Guanghai, HUANG Jianpeng, JIANG Xintao, XIE Ruitao, MA Qian, CHEN Gang
, Available online  , doi: 10.12131/20220227
The gill tissue of cobia (Rachycentron canadum) is sensitive to water temperature changes. In order to investigate the effect of low temperature stress on juvenile cobia, and reveal its response mechanism to low temperature stress, we designed two low temperature groups (18 ℃ and 21 ℃) and one control group (28 ℃), to analyze the antioxidant responses, expression of apoptosis-related genes and histological structure of the gills on 0, 4th and 7th day after the stress. The results show that the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the low-temperature groups were significantly lower than those in the control group (P<0.05), while the malondialdehyde (MDA) mass concentration in the low-temperature groups was significantly higher than that in the control group (P<0.05). The expression of apoptosis-related genes bax, caspase-9, caspase-3, p53 and mdm2 increased significantly in the low-temperature groups, while the expression of Bcl-2 decreased significantly on 4th and 7th day (P<0.05). The TUNEL results reveal that low-temperature treatment increased the cell apoptosis rate of the gills, and caused lesions including fusion of secondary lamellae, necrosis of epithelial cell and hyperplasia of chloride cells. The results indicate that low-temperature stress causes oxidative stress, induces apoptosis and damages the structural integrity of the gills, which suggests that normal physiological functions of juvenile cobia can be affected by low temperature significantly.
Study on large-scale artificial seedling breeding technology of Tapes dorsatus
ZHANG Kexin, LUO Zexin, ZHANG Yuan, ZHAN Jianqiang, LU Yining, LIU Zhigang
, Available online  , doi: 10.12131/20220262
Based on the problem of seedling supply of Tapes dorsatus, we studied the key techniques of seedling breeding of T. dorsatus by a single factor comparison test, so as to provide references for its large-scale artificial breeding. The results show that: 1) With artificial temperature control, we used the compound algae in shrimp pond to promote the ripening of the parents instead of the pure monocytic algae, and the ripening rate was 282.6% higher than that of the control group. 2) By means of a series of measures such as warming and drying in shade to induce spawning, the rate of induced spawning increased by 50.9% compared with the control group. 3) In order to establish a closed seedling technology model, we added effective microorganisms to build a beneficial micro-ecosystem, and did not change the water during the seedling breeding period. The results reveal that the survival rate of larvae in pelagic period, juvenile growth rate and juvenile rearing rate were significantly higher than those of the control group. 4) We collected the spats by using vertival seedling collection combined with the bottom of the pool. The juvenile rearing rate and yield per unit area increased by 76.6% and 76.5%, respectively. 5) Taking the parents with body mass above 5% as breeding group, the shell length, body mass of juvenile and juvenile rearing rate increased by 6.6%, 17.03% and 8.43%, respectively compared with the control group. However, the variable coefficients of juvenile shell length and body mass decreased by 29.13% and 55.29%, respectively. The realized heritability "h2" of shell length and body mass at the juvenile stage reached 0.65 and 0.72, respectively. This study designed a new integrated innovative technology for the artificial seedling breeding of T. dorsatus, which achieves significant economic benefits and lays a foundation for the realization of its large-scale breeding of seedlings.
Structural characteristics and relative influencing factors of macrobenthos community in intertidal zone of Daya Bay
LI Xue, LI Yafang, CHEN Qinghua, NING Jiajia, WANG Lianggen, XU Lei, HUANG Delian, LIU Shuangshuang, ZHONG Chao, ZHANG Jian, WANG Xuehui, DU Feiyan
, Available online  , doi: 10.12131/20220202
In recent years, the structure of macrobenthic community and ecological functions of intertidal zone in Daya Bay have changed significantly due to the influence of various factors such as anthropogenic disturbances. In order to understand the changing patterns of ecosystem functioning in the coastal waters of Daya Bay, we obtained the data on the macrobenthos and habitats in six intertidal sections (Three sands, two muds and one artificial shoreline) in summer (August) and autumn (November) of 2021, and analyzed their community structure characteristics and influencing factors. The results show that a total of 118 species were identified, including 82 species in summer and 64 species in autumn, among which molluscs had the largest quantity in both seasons followed by arthropods and annelids. The mean biomasses of the six sampling sections in two seasons were 589.36 and 188.22 g·m−2, and the mean abundances were 356.39 and 1 010.3 ind·m−2, respectively, with molluscs and arthropods accounting for a higher proportion. The results of cluster analysis and multidimensional scaling show that the macrobenthic fauna community in the survey areas displayed significant spatial differences. The macrobenthos in the intertidal zone of Daya Bay could be divided into three communities: sand facies, mud facies and artificial shoreline, among which the artificial shoreline community had the highest diversity index and best community stability. Distance-based redundancy analysis indicates that the structure of intertidal macrobenthic community was mainly affected by sediment type and anthropogenic disturbance.
Study on bacterial community structure in rearing water in small greenhouse of Litopenaeus vannamei
FANG Yuan, LI Hui, WANG Libao, WAN Xihe, SHI Wenjun, YANG Zeyu, JIANG Qi, SHEN Hui, HU Runhao, GUAN Xiaoping, YANG Jiaxin
, Available online  , doi: 10.12131/20220205
In recent years, small greenhouse has been a hot model of Litopenaeus vannamei culture. In order to elucidate the structure and changes of the microbial community in the rearing water of L. vannamei culture in small greenhouse and explore the reasons for high yield and high efficiency of this model, we analyzed the composition and function of the microbial community on 2nd, 44th, 69th and 96th day of water in the small greenhouse based on 16S rRNA sequencing results. The results show that the richness and diversity of water microbial community at late stage of small greenhouse were significantly higher than those at early stage. During the whole culture process, the dominant bacteria at the phylum level were Proteobacteria, Bacteroidetes and Actinobacteria, among which the abundance of Proteobacteria increased significantly on 69th day, and the abundance of Actinobacteria increased at early stage but decreased at later stage. At genus level, the abundance of Candidatus_Aquiluna was the highest on 2nd day (28.7%). Marivita was enriched at middle stage, with the highest abundance on 69th day (9.94%). The abundance of Flavobacterium gradually increased with the culture time, reaching the highest on 96th day (11.63%). PICRUSt2 predicts the function of the microbial communities, and the abundances of metabolic function in the top 20 were significantly higher on 69th and 96th day than on 2nd day. In particular, the functions of terpenoids and polyketides metabolism, lipid metabolism, xenobiotics biodegradation and metabolism were highly enriched. Through FAPROTAX identifying, the abundance of chemoheterotrophy increased significantly at the late stage. The correlation analysis of environmental factors shows that total nitrogen (TN) and chemical oxygen demand (COD) had the greatest impacts on the microbial community structure in greenhouse model. Microorganisms such as Marivita, Candidatus_Aquiluna and Rhodopirellula played the roles in sequestration of carbon and reduction of nitrogen and phosphorus. In conclusion, under the high density and high nitrogen and phosphorus culture conditions, the water microbial community in the small greenhouse played an important role in maintaining the stability of water environment and enhancing the immunity and disease resistance of prawns.
Purification effect of searice paddy field on brackish water environment of shrimp culture
ZHANG Xinxin, LI Ting, LI Shaowen, ZHU Changbo, ZHANG Bo, SU Jiaqi, RUAN Guoliang, ZHANG Xiaoyang
, Available online  , doi: 10.12131/20220261
In order to explore the water purification effect of paddy field in the combined pond-paddy field farming system, we analyzed the biofiltration ability of sea rice paddy field in two shrimp culture seasons (Summer and winter). In the summer trial, the tail water of shrimp culture was purified by sea rice and common rice paddy fields with different planting densities, and the purification efficiency of sea rice paddy fields with standard planting density was the highest. After six weeks, the removal rates of ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total phosphorus and chemical oxygen demand in standard sea rice treatment were 81.6%, 68.2%, 63.7%, 91.0% and 29.7%, respectively, which were significantly higher than those in the control treatment (P<0.05), and the removal rates of ammonia nitrogen and total inorganic nitrogen were significantly higher than those in the common rice treatment (P<0.05). In the winter trial, sea rice was harvested in the shrimp-rice pond, the average concentrations of ammonia nitrogen, nitrite nitrogen, total inorganic nitrogen and total particulate matter in the shrimp-rice ponds decreased by 51.5%, 40%, 36.7% and 11.2%, respectively, compared with the shrimp monoculture ponds (P<0.05). The average concentrations of nitrate nitrogen, total phosphorus and chemical oxygen demand, particulate organic matter and particulate inorganic matter were not significantly different from those in monoculture ponds (P>0.05). The results show that the sea rice paddy field has certain purification ability in both rice growing season and non-growing season, which helps to maintain a good water environment for shrimp growth.
Spatial heterogeneity of relationship between distribution of Uroteuthis chinensis and marine environment in offshore waters of northern South China Sea
CAI Yancong, SUN Mingshuai, XU Youwei, CHEN Zuozhi
, Available online  , doi: 10.12131/20220288
Cephalopods are one of the most potienial fishery species but are vulnerable to environment changes, and their complex interactions lead to the spatial heterogeneity in resource-environment relationship. Uroteuthis chinensis is an important economic species in the offshore waters of northern South China Sea, occuping a dominant position in the fishery community structure. Therefore, understanding the spatial characteristics of the resource-environment relationship is beneficial to its development, utilization and protection. Based on the fishery resources survey data in the offshore waters of northern South China Sea in summer of 2014, we established a geographically weighted regression (GWR) model to explore the spatial characteristics of the relationship between the resource distribution of U. chinensis and the marine environment in this area, and to reveal the main influencing factors. The results of model evaluation indexes show that the minimum Akaike information criterion (AIC) and adjusted R-Square (\begin{document}$R_{\rm{adj}}^2 $\end{document}) for GWR model were 224.81 and 0.46, respectively, both of which were better than those of the traditional global linear regression model. Thus, the GWR model could more truly reflect the spatial heterogeneity on resource-environment relationship for U. chinensis. The impact of chlorophyll a on resources was a coexistence of positive and negative effects in the whole sea, but the other environment variables had consistent positive effects on resources. The stock distribution in the coastal waters of Guangdong was mainly affected by sea surface salinity, sea surface temperature and chlorophyll a, and the latter two were the primary influencing factors in western Guangdong and Pearl River Estuary-Eastern Guangdong, respectively, but the Beibu Gulf was only significantly affected by water depth. Under the impact of dominant environmental factors, U. chinensis stock denstiy showed obvious regional differentiation characteristics, especially those in the Pearl River Estuary-Eastern Guangdong significantly different from the other areas. In conclusion, GWR model provides an effective means to explore and understand the local characteristics of cephalopod resource-environment relationship.
Fish habitat suitability analysis of Dongta spawning ground of Pearl River based on fisheries acoustic survey
WU Zhi, LI Yuefei, ZHU Shuli, YANG Jiping, XIA Yuguo, LI Jie
, Available online  , doi: 10.12131/20220283
As the largest spawning ground, the Dongta spawning ground is an important habitat for many rare and unique fish in the Pearl River, playing an important role in maintaining the supplement and diversity of early fish resources in the middle and lower reaches of the Pearl River. In order to evaluate the fish habitat suitability, we selected the suitable habitat of fish by a hot spot analysis based on the acoustic data from 2016 to 2019. Taking the terrain factors (Water depth, slope and aspect) as habitat indicators to calculate the fitness index range of each factor, we established the habitat suitability index (HSI) model by using the geometric mean method and calculated the HSI value. It is showed that the fish density ranged from 0.009 to 0.057 ind·m−3 in Dongta spawning ground. In terms of time, the fish density had been decreasing year by year, but in terms of space, the overall autocorrelation of fish distribution was not strong, while the local autocorrelation was strong in some areas. For example, the area adjacent to the spawning ground sandbar had been a hot spot in three years, and the "cold spot area" appeared in the downstream of the Datengxia Water Project and Shizui Section. The most suitable water depth range was 5–8 m, the suitable slope range was 1.0°–1.5° (Micro-slope), and the suitable aspect range was 90°–180° (Southeast direction). The average HSI value was 0.31±0.22, ranging from 0.02 to 0.95, and the high value was obtained mainly on both sides of the sandbar of the Dongta spawning ground but scattered on both sides of the river, where might be potentially suitable habitat areas. The main channel was basically the area with low HSI values. The HSI model was verified based on the acoustic data in 2017, and the fish density and HSI showed a linear positive correlation, which indicates that the established model in this paper can be used to analyze and evaluate the habitat suitability of river fish.
Immune protective efficacy of recombinant vaccine against Aeromonas hydrophila secreted proteins on zebrafish
LIN Xiaoke, WANG Yuqian, LIN Meizhen, HUANG Dongping, MIAO Yuxuan, LIN Xiangmin
, Available online  , doi: 10.12131/20220266
Aeromonas hydrophila is a prevalent aquatic pathogen that poses a risk to fishery production and can cause zoonotic diseases. Therefore, prevention of transmission and infection of A. hydrophila is a critical issue to address. To develop a potential subunit vaccine and provide a theoretical basis for better preventing and treating A. hydrophila disease, we selected eight secreted proteins (ORF0322, ORF3982, ORF2874, ORF1767, ORF3984, ORF2546, ORF0472 and ORF1609) from an A. hydrophila virulent strain LP-2 based on our previous research. The qPCR test shows that all selected proteins were expressed normally, then they were cloned and purified. The cloned and purified recombinant proteins were administered to zebrafish through injection. After 28 days of immunization, qPCR analysis detects increasing expression of all relevant immune genes in the zebrafish, suggesting that these recombinant proteins were capable of eliciting an immune response. In order to evaluate the immune protection offered by the eight selected secreted proteins, a bacterial challenge experiment was conducted. The results show that six of the secreted proteins (ORF3982, ORF2874, ORF1767, ORF3984, ORF0472, ORF1609) exhibited a relative immune protection rate (RPS) greater than 50%, indicating that they held promise as vaccine candidates against A. hydrophila infection.
Effects of cysteine addition to low-fishmeal diets on metabolism of lipid and protein in juvenile Trachinotus ovatus
LIU Jiaxing, GUO Huayang, ZHU Kecheng, LIU Baosuo, ZHANG Nan, XIAN Lin, ZHANG Dianchang
, Available online  , doi: 10.12131/20230030
To investigate the effect of cysteine on the metabolic disorders of juvenile Trachinotus ovatus (10.05 ± 0.05) g caused by low fishmeal, we prepared a basal pomfret diet by using plant and animal proteins (Chicken meal, soybean protein concentrate, fermented soybean meal, etc.) as partial substitutes for fishmeal, and then added 0 (Group C0, control group), 0.30% (Group C1), 0.60% (Group C2), 0.90% (Group C3) and 1.20% (Group C4) cysteine to make five isonitrogenous and isoenergetic diets. The results of a 56-day feeding trial show that: 1) Cysteine enhanced protein anabolism in T. ovatus by activating the S6K/PI3K/TOR/4E-BP1 pathway. Supplementation with 0.6%−0.9% cysteine up-regulated the mRNA levels of ribosomal protein S6 kinase (S6K), target of rapamycin (TOR), phosphoinositide 3-kinase (PI3K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) in muscle, increased total protein (TP) in muscle and serum as well as muscle crude protein content, reduced serum ammonia (SA) and urea nitrogen (UN) in muscle and liver, promoting protein deposition in muscle. 2) Supplementation with 0.6%−0.9% cysteine inhibited lipid anabolism by down-regulating the expression level of peroxisome proliferator-activated receptors gamma (PPARγ) in muscle, decreasing the transcript level and enzyme activity level of Acetyl-CoA carboxylase (ACC) and fatty acid synthetase (FAS), while it up-regulated the expression level of peroxisome proliferator activated receptors-alpha (PPARα) in muscle, resulting in high hormone-sensitive lipase (HSL) and carnitine palmitoyl transferase 1 (CPT1) expression with increased enzyme activity, which in turn promoted β-oxidation of fatty acids in muscle, reducing protein consumption due to catabolism for energy supply. Thus, protein deposition in muscle is promoted.
AHP-based evaluation on site selection for offshore cage culture
ZHANG Pingping, LI Zherui, SONG Huaiying, CAI Huiwen
, Available online  , doi: 10.12131/20220253
The planning and selection of appropriate location of cage culture areas are essential for improving the economic benefits and promoting the sustainable development of cage culture industry. However, several factors affecting cage culture include marine environment, production management and facility safety, which makes it a complex and multifactor decision-making process. Thus, developing an index system to evaluate the impact on the location of deep-water cage culture is important. This paper employs the analytic hierarchy process (AHP) to construct an index system model for deep-water cage culture site selection. The model includes three criteria layers and fourteen index layers, and quantitatively analyzed the relative importance of each criterion layer and index layer based on expert judgment. Natural factors are the most important indicators affecting the location of deep-water cage culture in the criteria layer, followed by restrictive factors and finally social factors. Among the fourteen secondary indicators, water quality was the most significant, while feed supply had the least impact. The AHP-based evaluation index system for deep-water cage culture site selection can accurately assess the importance of various factors. This findings are beneficial for appropriately arranging deep-water cage culture area, selecting regions suitable for deep-water cage culture, and providing guidance for optimizing and revising marine functional zoning.
Cloning and expression analysis of PCNA in Metapenaeus affinis
ZHANG Yan, LUO Zhiping, LI Yundong, YANG Qibin, JIANG Song, CHEN Chuanghua, HUANG Jianhua, YANG Lishi, CHEN Xu, JIANG Shigui, ZHOU Falin
, Available online  , doi: 10.12131/20220297
As a coprotein of DNA polymerase δ, proliferating cell nuclear antigen (PCNA) plays an important role in the process of DNA replication. There is a stage of vigorous cell proliferation during the ovarian development in Metapenaeus affinis, but little attention has been paid to its molecular mechanism. In this study, we applied rapid amplification of cDNA ends (RACE) technique to obtain the full length cDNA sequences of PCNA in M. affinis (MaPCNA), and analyzed the expression of MaPCNA related to ovarian development by real-time fluorescent quantitative PCR (qRT-PCR). The total length of MaPCNA was 1 144 bp, including 140 bp of 5' untranslated region, 221 bp of 3' untranslated region and 783 bp ORF encoding 260 amino acids. The molecular mass of MaPCNA protein was 28.82 kD and the theoretical isoelectric point was 4.5. The protein homology analysis shows that MaPCNA had high homology with other crustaceans. The result of tissue expression shows that Ma-PCNA was expressed in all tested tissues, with the highest expression in ovary (P<0.05). The expression of MaPCNA in ovary at different developmental stages showed significant changes (P<0.05), increasing from stage I to stage III gradually, decreasing significantly and then tending to be stable. The expression of MaPCNA showed a regular change trend at different larval developmental stages. The expression level of MaPCNA was the highest in oosperm, then began to decline, and became stable from the Nauplius VI. The results suggest that PCNA may play an important role in the ovarian development of M. affinis.
Diagnostic and pathological studies of epizootic ulcerative syndrome (EUS) outbreak in cultured albino Channa argus in Sichuan Province of China
FAN Wei, CHEN Mengzhu, GUO Xianghui, GENG Yi, CHEN Defang, OUYANG Ping, HUANG Xiaoli, LAI Weimin, WU Jun
, Available online  , doi: 10.12131/20220321
In order to determine the causes of the frequent occurrence of diseases in albino northern snakehead (Channa argus) in Sichuan Province of China during the cloudy, rainy autumn and winter, we carried out the reseach by techniques such as clinical observation, isolation and culture, as well as histology and molecular biology, etc.. Generally, the pathological study shows that the main manifestations of the diseased fish were skin peeling, exposing the subcutaneous muscle layer, and the deep ulcer of the muscle. Moreover, non-septate branching fungal hyphae with a diameter of 10–20 µm were observed in squash preparations under light microscopy. The pathogen was identified as invasive Aphanomyces invadans by isolation and purification and ITS sequence analysis. Histopathology reveals that the ulcer edge in the skin dermis and muscle was surrounded by mature granuloma. These granulomas could invade the normal muscles observed by naked eye and caused a further impact on the diseased fish. The findings indicate that the disease was Epizootic Ulcerative Syndrome (EUS), which is the first report of EUS in albino C. argus, providing the basic data for the identification and clinical diagnosis of A. invadans. The findings also suggest that a risk of host expansion of this fungus may exist.
Study on muscle fiber characteristics, metabolic enzymes and gene expression of caudal stalk of golden-backed carp (Cyprinus carpio var. Jinbei)
ZHANG Wenzheng, YANG Li, YAO Junjie, MENG Qingmi, JI Da
, Available online  , doi: 10.12131/20220320
Golden-backed carp (Cyprinus carpio var. Jinbei) is a common carp that has lived in rice fields for many generations through long-term natural and artificial selection. In order to promote its paddy field breeding model and provide data supports for the breeding of improved varieties by this model, we analyzed the caudal stalk muscle fibers, related metabolic enzymes and gene expressions by using histology, enzymology and molecular biology methods, and explored the adaptive characteristics of caudal stalk muscle growth under the shallow ecological conditions of rice field. The results show that the diameter of caudal stalk muscle fiber in paddy field group was larger than that in pond group at flowering stage and harvest stage with significant differences (P<0.05). The cross-section area of caudal stalk muscle fiber in paddy field group was larger than that in pond group at flowering stage and harvest stage, with significant differences at harvest stage (P<0.05), while the density of caudal stalk muscle fiber in paddy field group was smaller than that in pond group. There were significant differences at harvest stage (P<0.05). The activities of lactate dehydrogenase (LDH), catalase (CAT) and Ca2+-ATPase in metabolic enzymes were higher in paddy field group than in pond group at flowering stage and harvest stage. The expression level of peroxisome proliferation-activated receptor γ-coactivator α (PGC-1α) gene in paddy field group was significantly higher than that in pond group (P<0.05). The results reveal that the expression levels of adenylate activated protein kinase (AMPK) and silence-regulating factor 1 (SIRT1) gene in paddy field group were significantly lower than those in pond group at flowering stage and harvest stage (P<0.05). The resistance movement of the caudal stalk of golden-backed carp in rice field caused muscle hypertrophy, which was related with the activation of protein synthesis pathway, while its endurance exercise, was related with the mitochondrial biosynthesis. The higher PGC-1α expression level of golden-backed carp in rice flowering stage may be related with the increase of rice flowering, insects, biodiversity and biomass.