• ISSN 1000-0615
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Genomic analysis of Bacillus velezensis LF01 strain and the biocontrol effect of its secondary metabolites
ZHANG Defeng, GAO Yanxia, KE Xiaoli, WANG Yajun, REN Yan, SHI Cunbin
In Press  doi: 10.11964/jfc.20201012442
[Abstract](744) [FullText HTML](296) [PDF 3542KB](13)
Bacillus velezensis is a novel species in the Bacillus genus which exhibits a broad spectrum of antimicrobial activities due to it produces various secondary metabolites. The current research on B. velezensis mainly focuses on its use for the promotion of the growth of animals and plants, for antagonizing pathogens, and on investigating its gene cluster which play significant roles in biological control, drug research and development, and food fermentation. The aims of this study are to explore the gene clusters related to antagonistic substances of B. velezensis LF01 strain based on the whole genome sequencing, and to evaluate the biological safety and biocontrol effect of the antagonistic substances of the LF01 strain. In this study, the whole genome of the LF01 strain was sequenced based on the third generation Nanopore sequencing platform, and its taxonomic status was identified based on ANI and DDH online analysis, and the genetic evolution at genome level. The gene clusters related to antagonistic substances of the LF01 strain was analyzed based on antiSMASH software. The hydrolysis activity of the LF01 strain to carbohydrate was analyzed based on CAZyme database. The toxicity of the antagonistic substances of LF01 strain to Oreochromis niloticus and Danio rerio was evaluated by intraperitoneal injection. The biocontrol effect of the antagonistic substances of LF01 strain to O. niloticus was evaluated by artificial infection after 5 d of feeding O. niloticus. The complete genome of LF01 strain was a total length of 3974023 bp and the GC content was 46.56%, and it contains 3843 coding genes. Compared to B. velezensis, the ANI and DDH values of LF01 strain were ≥97.66% and ≥80.10%, respectively. Furthermore, the genomic evolution analysis showed that LF01 strain was clustered with B. velezensis. These results indicated that LF01 strain was identified as B. velezensis at the genomic level. The LF01 strain contains nine gene clusters related to antagonistic substances, including bacillaene, bacillibactin, bacillomycin D, bacilysin, difficidin, fengycin, macrolactin H, plantazolicin and surfactin, which accounts for 8.83% of the total genome sequences. In addition, LF01 strain contains a large number of CAZymes related to the degradation of cellulose, hemicellulose, starch, chitin, pectin, peptidoglycan and glucan. The antagonistic substances of the LF01 strain showed high biological safety to O. niloticus and D. rerio, and they were significantly enhanced the resistance of O. niloticus against S. agalactiae infection. In conclusion, the LF01 strain contains large number of gene clusters for biosynthesis of secondary metabolites related to antagonistic substances. The antagonistic substances were found to be safe for O. niloticus and D. rerio, and feeding O. niloticus with them significantly improved the diseases resistance of fish. Therefore, the antagonistic substances of LF01 strain have a broad development and application prospect as biocontrol agents to improve bacteria diseases control in aquaculture.
Continuous observation on early embryonic development of Hyriopsis cumingii under in vitro culture condition and analysis of biological zero point and effective accumulated temperature
HU Honghui, BAI Zhiyi, GUO Sipeng, FENG Shangle, SUN Tianyang, CHEN Weimin
In Press  doi: 10.11964/jfc.20201212524
[Abstract](40) [FullText HTML](24) [PDF 1282KB](0)
Hyriopsis cumingii is a unique freshwater breeding pearl mussel in our country. It has the reproductive biology characteristic that the fertilized eggs develop to the larva in gills. The unique reproductive biology characteristic make the offspring produced by the mussels random in the process of artificial breeding and restrict the application of modern biological breeding techniques to mussels such as triploid induction, gynogenesis and gene editing. In this study, in order to do research on the progress of H. cumingii embryos and explore the in vitro culture its early embryos, male and female gametes obtained by anatomy were used as materials for in vitro fertilization and in vitro culture with isoosmotic balance salt solution (BSS) suitable for freshwater mussels. And the morphological characteristics of each stage of embryo were observed with the required time for development recorded. Meanwhile, the embryos in its nurturing pouch of outer gill were continuously observed and the water temperatures were recorded day and night at the same time, then calculate the embryonic developmental biological zero point and examine the reliability of the biological zero point. After that, effective accumulated temperature of each embryonic development stage was calculated according to the biological zero point that is confirmed. Results show that when the water temperature is (25 ± 1) °C, the anatomy of the sperms and eggs were mixed after diluting by BSS saline and observed fertilized eggs can develop to morula stage. The fertilized eggs develop to polar body emissions at 1.8 h, develop to 2-cell stage at 2.8 h, develop to 4-cell stage at 5.6 h, develop to 8-cell stage at 10.5 h, develop to 16-cell stage at 13.9 h, and develop to morula stage at 17.3 h after observing under optical microscope. And then embryos did not change, and some of embryos were deformed. The morphological characteristics of embryos at each stage under in vitro culture condition is similar to that in the gills. Meanwhile, when the average water temperature in the pond was 26.54 °C, 28.08 °C and 29.51 °C, it took respectively 10 d, 9 d and 8 d for embryos to develop into mature glochidium. And the biological zero point for embryonic development of H. cumingii was 14.81 °C and is confirmed reliable after examining. The effective accumulated temperature were 12.95 °C×d for embryos developing to cleavage stage, 25.99 °C×d for embryos developing to blastocyst stage, 42.27 °C×d for embryos developing to gastrulation stage, 69.21 °C×d for embryos developing to glochidium stage and 118.14 °C×d for embryos developing to cleavage stage mature mlochidium stage, respectively according to the biological zero point that is calculated previously. The results attempt to cultivate H. cumingii embryos under in vitro condition, which confirmed the feasibility of cultivate H. cumingii embryos under in vitro condition, and then analyze and calculate the biological zero point and effective accumulated temperature of early embryonic development. The results of this study can provide reference for the researches on artificial breeding and development of modern biological genetic breeding technology of H. cumingii.
Accumulation of nitrite and responses of energy metabolism exposed tonitrite stress in Litopenaeus vannamei
LI Zhongshuai, MA Shen, SHAN Hongwei, WANG Teng, XIAO Wei
In Press  doi: 10.11964/jfc.20201112474
[Abstract](611) [FullText HTML](260) [PDF 7585KB](22)
Litopenaeus vannamei is one of the most important breeding economic varieties in the world because of its fast growth, strong environmental adaptability, and short growth cycle. Along with the intensive culture model of L. vannamei popularized rapidly, large quantities of harmful substances accumulate in the culture environment which seriously affect the growth and health of L. vannamei. Nitrite enters through gills and accumulates in tissue, which has severely toxic effects on cultured L. vannamei. In the present study, to explore the accumulation of nitrite and changes in enzymes activities related to energy metabolism exposed to nitrite in L. vannamei [body length (6.8 ± 0.3) cm, weight (4.0 ± 0.6 g)], shrimps were exposed to four nitrite concentrations of 0 (control), 0.8 (11.2 mg/L NO2-N), 4.0 (56 mg/L NO2-N) and 8.0 mmol/L (112 mg/L NO2-N) for 96 h and then recovered for 12 h. Each experimental treatment included six replicates. Three replicates were used for sample collection, and the other three replicates were used to calculate the cumulative mortality of the L. vannamei. At 0, 6, 12, 24, 48 and 96 h of the nitrite stress, the hemolymph, hepatopancreas, muscle, gill and intestinal of 9 L. vannamei in each group were randomly selected for the determination of the index. Additionally, death number were recorded every 12 h. The results indicated that the shrimp mortality rate increased with nitrite concentrations. At the end of nitrite stress, shrimp mortality in control group, 0.8 mmol/L group, 4.0 mmol/L group and 8.0 mmol/L group were 10.7%, 32.0%, 42.7% and 52.0%, respectively. Within 6 hours of exposure, nitrite accumulated significantly in the gill, hemolymph, intestine, hepatopancreas, and muscle tissues of L. vannamei, and was positively correlated with stress concentrations. The maximum accumulation of nitrate in gills, hemolymph, hepatopancreas, intestine and muscle were 50.1 mg/kg, 43.2 mg/L, 20.7 mg/kg, 33.5 mg/kg and 14.9 mg/kg. In the same stress concentration group, nitrite accumulated the most in gill and the least in muscle, and the accumulation in gill was about 3 times than that in muscle. The activity of Na+-K+-ATPase in hepatopancreas and muscle of L. vannamei were significantly increased at 0.8 and 4.0 mmol/L, but significantly decreased in muscle of 8.0 mmol/L during the exposure period. The activity of AMPK in the hepatopancreas in the stress groups increased compared to the control group, and showed a positive correlation with the stress concentration. During the recovery period, except for hemolymph (8.0 mmol/L group), 1-hour recovery rate of nitrite in L. vannamei tissues in the stress groups were above 50%, and the hepatopancreas and gill showed the highest recovery efficiency exceeding 74%. The recovery time of hemolymph, gill and intestine were the shortest within 6 hours. In addition, the content of nitrite in water increased significantly. This study indicates that nitrite can be accumulated to shrimp tissues in a short time and accelerate the process of energy metabolism. Nitrite would excrete from the body rapidly during recovery in order to reduce the toxic effects. The results of this study will provide reference for alleviating the toxic effects of nitrite on cultured shrimp.
Preparation and immune protective efficacy analysis of an inactivated vaccine against infectious hematopoietic necrosis (IHN)
CHEN Guihua, XU Liming, ZHAO Jingzhuang, REN Guangming, SHAO Yizhi, LU Tongyan
In Press  doi: 10.11964/jfc.20210512833
[Abstract](39) [FullText HTML](19) [PDF 3427KB](0)
Infectious hematopoietic necrosis disease (IHN) is an acute infectious viral disease that can cause sudden death of salmon. Vaccine immunization is the most effective way to prevent and control the disease. At present, there is no commercial vaccine to prevent the disease in China. The objective of the present study was to prepare an inactivated vaccine against IHN and evaluate its protective immunity in Oncorhynchus mykiss. In this study, infectious hematopoietic necrosis virus (IHNV) were successively cultured on Epithelioma papulosum cyprinid (EPC) cells with different multiplicity of infection (MOI). The optimal proliferation patterns of IHNV on EPC cells was determined by measuring the titer of IHNV in each passage combining with the virus harvest time. IHNV was inactivated by β-propanolactone (BPL) at different final concentrations at 24 °C, and the inactivity was then verified in vitro and in vivo to determine the optimal inactivation condition. Inactivated IHNV prepared with the optimal inactivation protocol was intraperitoneally injected to O. mykiss [(10±2) g)] with different doses, and the protective effect of the inactivated vaccine was analyzed by detecting relative percent survival (RPS) after challenge, expression levels of immune-related factors and serum neutralizing antibody titers at different time post vaccination. It was shown that different proliferation patterns had some effects on the proliferation of IHNV on EPC. We chose MOI of 0.0001 as the best inoculation dose on EPC cells, and the virus was harvested on 3 days post inoculation at 15 °C. The in vivo and in vitro safety tests showed that the best inactivation condition was to inactivate IHNV at 24 °C for 24 h with the final concentration of 3.0 mmol/L BPL. 10 μL per fish was chose as the optimal immunization dose, and more O. mykiss were immunized. The RPS was 91.37%, 84.28%, 84.15% and 47.5% on 7, 21, 45 and 60 d post immunization (d.p.i), respectively, and significant difference was observed on RPS between 60 d.p.i and other time points. Compared with the negative group, the expression levels of Mx-1 and IFN-γ were significantly up-regulated in spleen and head-kidney on 7, 15 and 30 d.p.i, and reached the maximum on 7 d.p.i (5 folds). The expressions of CD4 and IgM gene were significantly up-regulated in spleen and head-kidney on 15 d.p.i. In the detection of neutralizing antibody titer, the average neutralizing antibody titer in O. mykiss serum was 67.25, 43.40 and 29.78 on 30, 45 and 60 d.p.i respectively, with a decreasing trend and significant differences within each group. The results indicated that the IHN-BPL inactivated vaccine developed in this study could induce specific and non-specific immune response in, and could provide significant immunoprotection, which will provide references for the development of inactivated vaccines against IHN.
Effects of kelp enzymatic hydrolysis extract on the growth and hepatopancreas transcriptome of Ictalurus punctatus
LÜ Hao, YE Yuantu, YI Haoming, SUN Fei, SHI Yaoyao, LÜ Bin, ZHOU Wei, JIANG Rong
In Press  doi: 10.11964/jfc.20201012436
[Abstract](39) [FullText HTML](22) [PDF 1622KB](1)
The aim of this study was to investigate the effects of kelp enzymatic extract on the growth and hepatopancreas transcriptome of Ictalurus punctatus. We prepared different diets with enzymatic extract of kelp addition amount of 0 g/kg (S), 0.3 g/kg (KP3), 0.5 g/kg (KP5), 1.0 g/kg (KP10), 1.5 g/kg (KP15), 2.0 g/kg (KP20) to feed channel catfish in cage-culture for 60 days. Channel catfish [initial body weight (51.18±1.14)g] as exprimental object were randomly divided into 6 groups with 3 replicates per group and 40 fishes per replicate. The results showed that: ① Compared with the control group S, the addition of kelp enzymatic extract in diet has no significant effect on the suvival rate(SR) of channel catfish, the specific growth rate(SGR) increased by 1.20% to 5.39%, and the feed coefficient rate(FCR) decreased by 1.65 % to 9.09%. A quadratic polynomial regression analysis was carried out with SGR and FCR as the targets respectively., and the optimal addition amount of kelp enzymatic hydrolysis extract in the feed was 0.98 g/kg and 0.93 g/kg. The condition factor(CF) and viscero-somatic index(VSI) decreased significantly in groups KP10 to KP20, and the hepatosomatic index(HSI) decreased significantly in group KP10. The moisture, crude fat, crude protein and ash of fish have no significantly difference in all groups. ② Height of duplicature in group KP3, height and width of duplicature and thickness of muscularis in group KP5, thickness of muscularis in group KP10 were all significantly higher than those in group S. ③ Total RNA was extracted from S and KP10 groups’ hepatopancreas. Transcriptome sequencing results showed that there were 81 significantly down-regulated genes and 199 up-regulated genes. GO functional classification analysis results indicated that differentially expressed genes(DEGs) are annotated to items such as DNA transcription, metal ion binding, membrane and membrane composition. According to the results of KEGG pathway analysis, we found that DEGs are mainly enriched in 12 related pathways including cell proliferation and differentiation, hormone regulation, lipid metabolism, carbohydrate metabolism, growth factor metabolism and so on. Our studies have indicated that adding kelp enzymatic extract to diet can promote the growth of I. punctatus, reduce feed coefficient, have positive effects on the intestinal morphology and the glucose and lipid metabolic capability of liver and pancreas, the suitable addition amount was 0.93 ~ 0.98 g/kg.
Influence factors on the netting lost rate of gillnet in waters near China
SONG Liming, CHEN Mingrui, DING Ruizhi, WANG Di, ZHOU Wang, LI Yiting
In Press  doi: 10.11964/jfc.20200512272
[Abstract](54) [FullText HTML](19) [PDF 1360KB](2)
The primary source of ALDFG is from the coastal and oceanic fishery and the maximum risk to produce ALDFG is from the coastal fishing industry. Gillnetters along the coast of China accounted for about 56% of the total number of fishing boats along the coast of China in 2018, and were one of the biggest potential source to produce ALDFG in China. Lost netting of gill net can keep the high rate of ghost fishing more than 2 years. ALDFG produced by the gill net fishery along the coast of China will cause great influence to the coastal marine ecosystems in China. In order to understand the factors and their impact degree on the netting lost rate of gillnet in waters near China, a questionnaire survey was conducted among the Chinese coastal fishermen from June to December, 2019 and the areas were covered in Liaoning, Shandong, Jiangsu, Zhejiang and Guangdong province. The data from 41 gillnetters were collected including 13 variables, e.g. gross tonnage, power, vessel length, vessel age, captain age, annual fishing day, average voyage day, voyage gear carrying weight, net average weight, annual procurement number, annual gear procurement weight, fishing depth and the lost numbers of gillnet netting. Based on the questionnaire survey data, software SPSS 23 was used to analyze the multicollinearity among 12 independent variables, and eliminate gradually 3 variables there were multicollinearity with other independent variables. The remaining 9 independent variables there was no multicollinearity among them were used to analyze the relationship with the netting lost rate of gillnet in waters near China by GAM and to determine the best GAM based on the AIC value. The results indicate that, (1) The factors (explanation deviation) that effect on the netting lost rate of gillnet (RG) in waters near China are as follows: average voyage day (86.8%), annual fishing day (4.2%), voyage carrying netting weight (2.8%), fishing depth (2.4%), gross tonnage (0.9%) and annual gear procurement number (0.1%); (2) The GAM can be used to study the relationship between the netting loss rate of gillnetters and the fishing boat parameters, annual fishing gear procurement information and fishing ground information; (3) With the increase of voyage day and annual fishing day, RG shows an increasing trend; (4) With the increase of fishing depth and the voyage carrying netting weight exceeding 18000 kg, RG shows an decreasing trend. The measures recommended to reduce the netting loss rate of gillnetters are as follows: (1) The voyage day should not exceed 30 days and reduce the annual fishing day; (2) According to the gross tonnage of fishing boat, the voyage carrying netting weight should be more than 18000 kg; (3) The fishing depth and fishing area should be regulated according to the height of gillnet gear. China should specify the maximum height of gillnet gear according to the current and seabed topography of the fishing ground in waters near China; (4) The gross tonnage of fishing boat should be smaller than 200 gross tons.
Effects of threonine supplementation in poultry by-product meal (petfood grade) replacement diet on growth performance, intermediary metabolism and immunity response in largemouth bass (Micropterus salmoides)
XU Yujue, WANG Wenqiang, YANG Peng, HE Chaoqun, QIN Yawen, SONG Fei
In Press  doi: 10.11964/jfc.20201112498
[Abstract](266) [FullText HTML](92) [PDF 2714KB](6)
In order to investigate the effects of different dietary threonine levels on growth performance, glucose and lipid metabolism, immunity and utilization rate of poultry by-product meal (petfood grade) of largemouth bass(Micropterus salmoides). Three isonitrogenous and isolipid diets were designed using M. salmoides with an initial body weight of (4.16±0.06) g as the research subjects (TC diet: threonine control group, LH diet: low threonine group and TS diet: threonine supplementation group) were cultured for for 8 weeks. Present results showed that compared with the TC diet, the LH diet significantly decreased the growth performance, feed efficiency and body nutrient composition, threonine addition could promote those differential effects caused by fishmeal totally substituted by poultry by-product meal. Moreover, the LH diet also suppressed the concentration of plasma nutrients and free amino acids than the control diet. TS diet had significant effects on elevating the plasma free amino acids concentration and made no notable difference compared to the TC diet. The mRNA expression level demonstrated that threonine supplementation markedly ameliorated the inhibition of anabolism, aggravation of catabolism and cellular inflammatory which caused by complete replacement of fishmeal with poultry by-product meal. Studies have shown that appropriate threonine supplementation could promote the growth performance by improving nutrient anabolism and immune response and inhibiting catabolism in M. salmoides.
Targeted regulation of miR-305-5p on Macrobrachium nipponense MnCHT3A gene in vivo
YUE Kaidi, CHEN Ke, DU Juan, LÜ Yanjie, YANG Hong, NING Qianji
In Press  doi: 10.11964/jfc.20200912427
[Abstract](34) [FullText HTML](19) [PDF 2539KB](0)
In order to explore the regulatory effect of microRNA (miRNA) on Macrobrachium nipponense chitinase 3A(MnCHT3A) gene, bioinformatics approach was firstly used to predict and screen the miRNA--miR-305-5p, which binds specifically to MnCHT3A. Using qRT-PCR, biochemical and histological methods, the regulation of miR-305-5p on target gene MnCHT3A was studied under in vivo. The results showed that the expression change of miR-305-5p was negatively correlated with MnCHT3A during the molting cycle of M. nipponense. The level of miR-305-5p peaked at stage C and was the lowest at stage A, while the expression trend of MnCHT3A mRNA was opposite. After injection of miR-305-5p mimics or miR-305-5p inhibitor, the transcription level of MnCHT3A was decreased by 60% or increased by 166%, and the activity of MnCHT enzyme, meanwhile, was decreased by 39.53% or increased by 133%, respectively compared with the control group. Histological results showed that a three-layer cuticle structure of carapace in stage C was observed by means of H-E staining, named epicuticle, exocuticle and endocuticle from the outer to inter. The images of chitin fluorescence staining identified the presence of chitin in the exocuticle and endocuticle. Results from scanning electron microscopy clearly showed the lamellar structure of the exocuticle and endocuticle. Compared with the control group, a thickening trend in the endocuticle with the lamellae as well as the blue fluorescence chitin stripe was observed in miR-305-5p mimics group. But in miR-305-5p inhibitor group, the culticular structure was disordered. Correspondingly, the blue fluorescence chitin stripe was not uniform and weakened in some areas. The results obtained above indicate that the target gene of miR-305-5p is MnCHT3A, and miR-305-5p can specifically inhibit the transcription of MnCHT3A in vivo.
The role of tissue inhibitor of metalloproteinase in the anti-Vibrio immunity of Haliotis discus hannai
ZHANG Minghui, ZHANG Qian, LIN Jinjin, ZHANG Lingjing, LIU Guangming, CHEN Yulei, CAO Minjie
In Press  doi: 10.11964/jfc.20201012430
[Abstract](92) [FullText HTML](52) [PDF 1728KB](9)
As an important economical shellfish in coastal area of China, abalone is susceptible to bacterial infection, especially Vibiro parahemolyticus. Similar to other invertebrates, Haliotis discus hannai resist pathogen infection to the host by innate immune response. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous protein regulators of the matrix metalloproteinases (MMPs) family. As MMP-1 was engaged in the innate immunity of abalone, the involvement of TIMP in the regulation of MMP-1 expression and activity as well as the immune responses merits further investigation. In this study, the role of TIMP in the innate immune responses of Haliotis discus hannai against V. parahaemolyticus infection and the interaction between TIMP and MMP-1 were investigated. The full length cDNA sequence of TIMP was obtained, and the expression of TIMP in different tissues of H. discus hannai were analyzed post Vibrio infection. The cloned TIMP cDNA sequence was 2291 bp in length. NetNGlyc 1.0 Server and Netoglyc 4.0 Server were used to analyze the glycosylation sites of TIMP. The results showed that TIMP have three potential N-glycosylation sites, namely Asn at positions 47, 77 and 152, and a potential O-glycosylation site, namely Thr at position 108. Multiple alignment of TIMP amino acid sequences from different molluscs showed that the similarities of TIMP in H. discus hannai with those of H. diversicolor, Crassostrea gigas and Tegillarca granosa were 76%, 18.9% and 19.3%, respectively. In the early stage of V. parahaemolyticus infection, the expression of TIMP in hemocytes and gill tissues were significantly up-regulated. To study the interaction between TIMP and MMP-1 in the anti-Vibrio immunity of abalone, RNA interference technology was used to knock down the expression levels of TIMP and MMP-1. After the silencing of MMP-1 gene in abalone, TIMP expression was significantly up-regulation. When TIMP expression was inhibited, MMP-1 expression decreased significantly. These results indicated that MMP-1 expression was positively regulated by TIMP, while TIMP expression was negatively regulated by MMP-1 in abalone. In conclusion, the present study established the interaction between TIMP and MMP-1 in abalone innate immunity against V. parahemolyticus infection. It also provided new insights for the prevention and control of pathogens in abalone culture.
DPiWE: a curated database for pathogenic bacteria involved in water environment
DONG Pengsheng, GUO Haipeng, WANG Yanting, CHENG Huangwei, WANG Kai, HONG Man, HOU Dandi, WU Yuhua, ZHANG Demin
In Press  doi: 10.11964/jfc.20210612935
[Abstract](160) [FullText HTML](64) [PDF 3189KB](7)
Pathogenic bacteria in the water environment are mainly monitored in the public health, food safety, aquaculture and other industries due to their major threats to the health of humans and aquatic animals, and the biosafety of aquatic products. However, pathogenic database involved in water environment pathogen is mainly constructed according to independent disciplines, and scattered in the fields of clinical medicine and aquatic animal diseases, which can no longer meet the high-throughput identification and biosafety evaluation of pathogenic bacteria involved in the water environment in the regional scale or ecological perspective. In this study, a database of pathogenic bacteria involved in water environment (DPiWE) was constructed by collecting the taxonomic information of pathogenic bacteria from humans, aquatic animals, mammal, plants, and cross-host comorbidities. A multi-threaded schedulable communication model and a multi-task mode global sequence matching algorithm were developed to construct DPiWE. The database collected 9 070 pathogenic bacteria strains, which belong to 14 phyla, 27 classes, 54 orders, 116 families, 221 genera and 1 097 species. The corresponding 16S rRNA gene sequences, host information and infection types of these strains were also collected in DPiWE. This database was deployed at a website (http://dayuz.com/) with the functions including web user management, pathogenic information retrieval, sequence upload, storage and alignment, and visualization of annotation result. Two examples were used to test the functions of DPiWE. The first result showed that, DPiWE can accurately construct a phylogenetic network of an unidentified bacterium (strain DS10−D19) isolated from cultural seawaters, according to its 16S rRNA gene sequence, and identify it as Photobacterium leiognathid. The result of network also showed that the network structure of strain DS10−D19 was similar with P. leiognathid and P. angustum. The second example showed that the compositions of pathogens in the intestines of three mariculture animals were significantly different through annotating the high-throughput sequencing data using DPiWE, and the rearing water in diseased groups were potential risk of spreading the comorbid pathogenic bacteria of human and fish. The DPiWE and its supporting data analysis process can provide new ideas and data foundations for high-throughput detecting the biosafety of water environment, protecting health of fishery ecology, and controlling diseases of aquatic animals, in the future.
Heterotrophic feeding of hermatypic corals in Luhuitou Sanya
GAN Jianfeng, YU Xiaolei, LUO Yong, HUANG Lintao, LIU Chengyue, JIANG Lei, HUANG Hui
In Press  doi: 10.11964/jfc.20200912399
[Abstract](98) [FullText HTML](42) [PDF 2367KB](3)
The acquisition of energy and nutrients is the basis of sustaining the life activities of hermatypic corals, which is mainly depended on the alimentation mode. Hermatypic corals are mixotrophic organisms, both autotrophic and heterotrophic. It is acquainted that photosynthesis by zooxanthellae is the basic form of autotrophy, but little is known about the heterotrophic feeding. To know more about it, three representative species in the Sanya Luhuitou Bay, which are Galaxea fascicularis, Pocillopora damicornis and Acropora muricata are selected in this study to test their feeding habits. Their feeding reaction to Artemia salina, copepod used in aquarium, yeast extract liquor and aquatic coral food are observed. What’s more, G. fascicularis’s feeding rate and digestion of A. salina are probed into. It’s observed that G. fascicularis ingests four kinds of food mentioned above, while A. muricata ingests none of them and P. damicornis only ingests A. salina and aquatic coral food. It’s firstly reported that P. damicornis ingests A. salina by mesenterial filaments and it ingests aquatic coral food through the cooperation between polyps. Moreover, G. fascicularis’s feeding rate of A. salina and the density of A. salina nauplii were well fitted into the Michaelis-Menten model. A. salina is completely digested by the G. fascicularis with 3 h. The research can deepen our knowledge about the feeding of hermatypic corals, especially in the process of artificial coral breeding.
Mutation in SRBI gene and its association with the red shell color in Meretrix meretrix
SHI Heming, DONG Yinghui, YAO Hanhan, BAO Yongbo, LIN Zhihua
Accepted Manuscript  doi: 10.11964/jfc.20201012432
[Abstract](117) [FullText HTML](57) [PDF 5222KB](10)
The hard clam (Meretrix meretrix) is one of the most commercially important cultured shellfish in China. The red shell clam is richer in carotenoids, which makes its shell color red and has higher nutritional value compared with the white shell clam. In order to understand the mutation of scavenger receptor class B type I (SRBI) and its association with the formation of red shell color in M. meretrix, we analyzed the SNPs of Mm-SRBI gene CDS by using direct sequencing among 181 red shell clams and 207 white shell clams. Immunofluorescence (IF) and western blot (WB) were used to analyze the expression characteristics of Mm-SRBI protein in the mantle of two shell color strains. The results showed that a total of 15 single nucleotide polymorphisms (SNPs) were detected, and there were only two types of mutation in Mm-SRBI: transition and transversion, and the ratio of the two was about 3∶1. Among the 15 loci, 4 loci were significantly associated with shell color. The statistical results indicated that in red shell strain the range of Ho was 0.309 4−0.442 0, He 0.468 8−0.494 6, and Ne 1.863 4−1.973 4, while in the white shell strain Ho was 0.231 9−0.328 5, He 0.324 4−0.500 0, and Ne 1.639 9−1.995 3. The PIC value evidenced that these loci were all moderately polymorphic (0.5>PIC>0.25). Additionally, all of them were on conserved sequences, in which c.723 A/G site was non-synonymous mutation that led to amino acid changes Ile723Val, and 4 loci were genetically strongly linked (D′>0.75). The results of IF and WB revealed that Mm-SRBI protein was higher expressed in the mantle of red-shelled clams compared to that of the white-shelled clams and was mainly expressed at the outer epithelium of the mantle. Moreover, the quantitative analysis of gray values demonstrated that Mm-SRBI protein expression in red-shell clams was approximately 4.5 times higher than that in white-shell clams. In summary, our results suggested that the mutations of Mm-SRBI and the high expression of its protein may lead to differences in the metabolism of carotenoids in M. meretrix, which may lead to the formation of red shell color. It also provided a helpful foundation to explore the molecular mechanisms of carotenoids metabolism underlying shell coloration and could be potentially applied to marker-assisted selection breeding programs for M. meretrix.
Research progress on recycle and high-value utilization of protein by-products from aquatic products
ZHAO Yong, WU Yi, LI Yufeng, LIU Haiquan, WANG Jingjing
In Press  doi: 10.11964/jfc.20200912391
[Abstract](126) [FullText HTML](52) [PDF 2350KB](2)
The production of aquatic products is always increasing worldwide, due to their high nutritional value. However, a large number of by-products is produced during the consumption and processing of aquatic products, causing serious resources waste and environmental pollution. On this basis, the by-products of aquatic products were developed and applied in many fields according to their different characteristics. Among them, the by-product proteins have been widely recycled and utilized in practice due to its unique functions and high added value. Therefore, this article reviewed the typically physical, chemical and biological methods for recycling the proteins from aquatic products. Meanwhile, we also introduced the research progress in the high-value utilization of by-product proteins from fish, crustaceans and shellfish, as well as their future development trend, with the purpose of further enhancing the comprehensive utilization of aquatic by-products and promoting the high-quality development of aquatic product industry. Generally, the aquatic products from fishing or aquaculture were often needed to be processed before their marketing. However, massive by-products were left after being processed, and they must undergo further treatment to obtain end-products with high added value. Among these by-products, proteins accounted for a large proportion and had higher nutritional value. The efficiency of traditional technology to recycle by-products of different aquatic products was limited, and the yield was very low, therefore, it was difficult to potently recycle a large number of by-product proteins from aquatic products. In the past century, the scientists in academic and industrial community have made great efforts to fully recycle the by-product proteins of aquatic products, and achieved many end-products through physical, chemical and biological methods. With the advance and innovation of science and technology, the recycling conditions of by-product proteins from aquatic products have been greatly optimized, and the recyclable types of by-products has been greatly expanded, as well as the proteins yield has been significantly improved. Therefore, the research hotspots of by-product proteins from aquatic products mainly focused on two aspects: innovative recycling methods and enhancing the added value of utilization. With the continuous development of molecular biology and polymer science, the researchers could modify the by-product proteins from aquatic products through physical, chemical and biological methods, which could not only improve and enhance their biological properties, but also broadened the applications of related products range. China's aquaculture output has been ranked first in the world for 28 consecutive years. However, the research on the high-value utilization and industrial application of aquatic by-products needed to be further improved. Moreover, from the perspective of industrial development, whether it was the introduction and development of by-product development technology, or the formulation and management of related product standards, China was facing many practical problems and challenges. Consequently, it was necessary to focus on the current situation and development trend, carry out the next step of planning, which introduced new vitality to the aquatic product processing industry. In the future, the commercial development of by-product proteins from aquatic products wound provide it with more possibilities and development prospects. More and more foods and drugs prepared using by-product proteins will be approved and promoted, which will provide a driving force for the further development of aquatic products industry.
Embryonic development and morphological characteristics of larvae and juvenile of cobia (Rachycentron canadum)
KUANG Jiehua, CHEN Gang, MA Qian, HUANG Jiansheng, ZHANG Jiandong, SHI Gang, WANG Zhongliang, TANG Baogui
In Press  doi: 10.11964/jfc.20200812389
[Abstract](737) [FullText HTML](296) [PDF 2800KB](30)
Cobia(Rachycentron canadum) is a highly prized recreational specie worldwide as well as a promising candidate for aquaculture because of its rapid growth rate, strong disease resistance and high quality flesh. Studying the morphometrics and physiology of embryos, larvae and juveniles to obtain information about their early life history is the first step and key to the successful aquaculture of a fish species. In order to find out the characteristics and rules of the early development stage of cobia, the morphological characteristics and developmental characteristics of embryo, larvae and juvenile were studied by microscopic observation. The fertilized eggs obtained by artificial spawning were spherically shaped and buoyant, there was an oil globule in the central, with an egg diameter of (1.245±0.065) mm and an oil globule diameter of (0.325±0.027) mm. The fertilized eggs hatched 26 h 30 min after fertilization in the sea water at (27.0±0.5)℃, salinity of 29 and pH of 8.3. The embryonic development process was divided into 7 stages, including fertilized egg stage, the cleavage stage, the blastocyst stage, the gastrula stage, the neurula stage, the organogenesis stage and the hatching stage (total 24 developing periods). The total length (TL) of newly hatched larvae was (3.254±0.096) mm. The larvae opened their mouths and exhibited blackened eyes at 3 days post hatching (dph) with a TL of (4.453±0.267) mm, meanwhile, the yolk-sac decreased in volume by approximately 80%. The yolk-sac and oil globule completely absorbed at 5 dph (TL of 6.007 mm±0.171 mm) and 7 dph (TL of 8.173 mm±0.317 mm) respectively, and the larvae completely entered the exogenous nutritional stage. The intestine of the newly hatched larvae was thin, short, and straight, and the intestinal physiological curve formed at 9 dph when the larvae were (10.053±0.594) mm in TL. The larvae started to develop into juvenile at 14 dph (TL of 19.933 mm±1.118 mm) when the development of the dorsal fin, pectoral fin, anal fin and caudal fin was completed. At 22 dph, the juvenile with a TL of (41.140±3.779) mm, there were some scales on the caudal peduncle formed. The 46 dph juvenile reached (116.667±5.916) mm in TL, the whole body surface covered with cycloid scales and their general appearance was similar to that of the adults, except for the shape of caudal fin. These results indicated that the fertilized egg diameter and newly hatched larvae size of cobia were both larger, and its early developmental characteristics had certain adaptability to the ecological behaviors. The present study could provide basic knowledge for investigating biology and artifical propagation of cobia.
Relationship between spatial distribution of Oratosquilla oratoria and environmental factors in Shandong offshore based on optimized BP neural network model analysis
LI Pengcheng, ZHANG Chongliang, REN Yiping, XU Binduo, XUE Ying
In Press  doi: 10.11964/jfc.20200712336
[Abstract](547) [FullText HTML](345) [PDF 6103KB](24)
As a common machine learning method, BP neural network model is widely used in species distribution models to analyze the relationship between biological distribution and environmental factors. Compared with the traditional regression models, this model can flexibly deal with the nonlinear relationship between variables. However, there are substantial uncertainties in parameter setting as result of its complex structure, which may affect the prediction and application of this model. This study considered there approaches to optimize the model parameters, including the group method of data handling, genetic algorithm and adaptive algorithm, to improve initial weights and the number of hidden nodes of the model, respectively. Seven combinations of optimized BP models were implemented based on the survey data obtained from fishery resources and environment in Shandong offshore between 2016 and 2017. Our results showed that there were significant differences in the predictive performance of the seven optimization models. The predictive performance of the one-way and two-way optimization models was approximately the same. The root mean square error and the square of residual error were 0.35 and 1.94 respectively, which were smaller than the initial model's 0.52 and 2.40, and the maximum correlation coefficient was 0.45, indicating that the optimization effect of the model was the best. After the comparison and optimization, it was found that the resource density of Oratosquilla oratoria was basically different with the increase of bottom salinity while the resource density of O. oratoria was significantly different with the increase of bottom temperature. In addition, the increase of water depth in the optimal model compared with the initial model was a key environmental factor,which had an important effect on the resource density of O. oratoria. In this study, the parameter optimization method of the BP neural network model was further developed, which proved that the parameter optimization had important effect on the prediction performance of the BP model, and the model optimization was of great significance for the analysis of the relationship between resource density and environmental factors.
Effect of yeast hydrolysate on non-specific immunity and antioxidant ability of Litopenaeus vannamei under low salinity stress
CHEN Yongkang, CHEN Zeen, LIANG Wuhui, LI Guoyong, HU Junpeng, YANG Zhilong, NIE Qin, CHI Shuyan
In Press  doi: 10.11964/jfc.20200912418
[Abstract](137) [FullText HTML](49) [PDF 1376KB](1)
Increasingly frequent typhoons bring large amounts of precipitation, causing drastic changes in water salinity and stress to aquatic animals. The large number of free radicals generated by stress may lead to aquatic animal mortality, which causes huge economic losses. Although pacific white shrimp, L.vannamei is tolerant to salinities of 1 to 50, drastic salinity changes may be detrimental to their health status. As a new type of protein, yeast-like substances contain a variety of functional substances and nutrients such as nucleic acids, small peptides, oligosaccharides, free amino acids, and rich B vitamins, which can improve the growth performance and health of animals, for example Epinephelus coioides, Scophthalmus maximus, Penaeus monodon. Previous studies have shown that the addition of yeast hydrolysate to feed can improve the non-specific immunity, the diversity of intestinal flora, the digestive enzyme activity, and the ability to utilize sugars and lipids in L. vannamei. It is interesting that yeast-like substances seem to play an active role in the immunoregulation response of aquatic animals to environmental stresses. This study aimed to investigate the effect of yeast hydrolysate addition to feed on the non-specific immune and antioxidant capacity of L. vannamei under salinity stress conditions.Shrimps [initial weight (15.82 ± 0.08) g] were randomly divided into 2 groups. The control group was fed with basic feed (Y0), and the experimental group was fed with experimental feed (Y3) supplemented with 3% yeast hydrolysate. After 15 days of raising, they were transferred to the water of salinity 4 (S4) and salinity 28 (S28) for low salinity stress with 3 replicates tanks of each group and 30 individuals in each tank. Groups were named Y0S4, Y0S28, Y3S4, Y3S28 according to a different combination of feed and salinity conditions. The results showed that there was no significant difference in the survival rate of the groups after transferring the shrimp to water with salinities of 4 and 28. The addition of yeast hydrolysate to the feed had no significant effect on serum phenoloxidase (PO) and total nitric oxide synthase (TNOS) activities in L. vannamei. At 1.0 h of low salinity stress, PO and TNOS activities were significantly higher in the Y3S4 group than in the Y0S4 group. The salinity factor had a significant effect on PO and TNOS activities: PO, TNOS activities were significantly higher in the S28 group than in the S4 group at 1.0 h. What’s more, the addition of 3% yeast hydrolysate to the feed significantly increased the hepatopancreas superoxide dismutase (SOD) activity of the shrimps. The studies have shown that the addition of yeast hydrolysate to the feed can increase the hepatopancreas SOD activity of L. vannamei and improve the antioxidant capacity of the shrimp. In the event of low salinity stress, the shrimp can quickly restore the PO and TNOS activities to normal levels, thus improving the resistance of L. vannamei to adverse environments.
Optimum dietary leucine requirement of juvenile sea cucumber Apostichopus japonicus
LIU Caili, WANG Jiying, LI Baoshan, SHEN Yubo, SUN Yongzhi, HUANG Bingshan, WANG Shixin
In Press  doi: 10.11964/jfc.20210112572
[Abstract](156) [FullText HTML](49) [PDF 7740KB](2)
A 60-d feeding trial was conducted to determine the dietary leucine requirement of juvenile sea cucumber Apostichopus japonicus with initial body weight (16.40±0.14) g. Six experimental diets were formulated with the graded leucine levels 1.29% (D1, control group), 1.63% (D2), 1.98% (D3), 2.22% (D4), 2.58% (D5) and 2.97% (D6) dry diets. The results showed that: There were no differences on survival rate among all groups (96.00%~98.67%). Both weight growth rate (WGR) and the specific growth rate (SGR) increased with increasing leucine content until reaching peak levels at 1.98% dietary leucine, but decreased thereafter. The WGR and SGR of D3, D4 and D5 groups were significantly higher than D1 group. The WGR reached maximum value of 100.84% in the D3 group. There were no significant effects on ratio of intestine weight to body wall weight (IBR) and ratio of intestine length to body length (IBL) of sea cucumber. The crude lipid contents of body wall was increased when dietary leucine content increased from 1.29% to 1.98% but decreased when the dietary leucine content exceeded 1.98%, D3 group was significantly higher than other groups, but there were no significant effects on moisture, crude protein and crude ash contents. Both methionine and leucine content of body wall were significantly increased by dietary leucine, but there were no significant effects on total amino acids (TAA). Both lipase and protease activities of intestinal were increased with increasing levels of leucine up to 1.98% diet and then decreased. The lipase of D3 group was significantly higher than other groups, meanwhile, the protease of D2, D3 and D4 groups were significantly higher than other groups. All of alanine aminotransferase (ALT), asparate aminotransferase (AST) and total antioxidant capacity (T-AOC) activities of intestinal were increased when dietary leucine content increased from 1.29% to 1.98%. There were no significant effects on AST activity when the dietary leucine content exceeded 1.98%, but the ALT and T-AOC activities were decreased. The T-AOC activity of D3 group was significantly higher than D1, D2, D5 and D6 groups. The catalase (CAT) and superoxide dismutase (SOD) activities reached maximum value when the dietary leucine content was 2.22%. The CAT activity of D4 was significantly higher than D3, D5 and D6 groups, The SOD activity of D4 was significantly higher than D1, D2 and D6 groups. The malondialdehyde (MDA) content was decreased when dietary leucine content increased from 1.29% to 1.98% but increased when the dietary leucine content exceeded 2.22%, the MDA contents of D3 and D4 groups were significantly lower than other groups. With WGR as evaluation indicator, quadratic regression analysis showed that the optimum dietary leucine of sea cucumber with body weight 16.40 g was 2.11% diet (10.37% dietary protein).
Preliminary analysis on regional differences of fishing habits of marine fishing vessels in Zhejiang Province–taking double trawlers as an example
LIU Yong, CHENG Jiahua, CHEN Ting
In Press  doi: 10.11964/jfc.20200412247
[Abstract](622) [FullText HTML](258) [PDF 6051KB](16)
Marine fishing vessels are now under localized management, but their offshore production has the characteristics of operating in waters under cross-regional jurisdiction. Traditionally, local fishing vessels generally have significant local characteristics because they follow local fishing experience and traditional fishing habits in inshore waters. However, with the steelization and large-scale of fishing vessels, the operating space of marine fishing continues to expand, so to understand and grasp whether the current marine fishing has regional characteristics differences, it has indispensable scientific and theoretical guiding significance for fishery sampling statistical survey and accurate fishery management. In this paper, the double-towing fishing vessels in Zhejiang, a major marine fishery province, are selected as the research object. Through a large sample random sampling survey, the annual production data of double-towing fishing vessels in three prefecture-level regions of Zhejiang Province are obtained, and the regional differences of fishing capacity (CPUE, catch per unit of effort) and catch structure are analyzed. The results show that except for September, there are significant regional differences in fishing capacity among the three regions, and Ningbo is relatively close to Taizhou, and there are significant differences in catch structure among the three regions in the whole year. Taizhou area is relatively independent and has its own category, while the similarity between Ningbo and Zhoushan is relatively high. Considering the interaction between fishing capacity and catch structure, the difference among the three regions is more significant. Although the production activities of China’s marine fishing vessels are wider and more flexible than those of 40 years ago, the differences in regional characteristics of fishing operations are still obvious, indicating that China’s marine fishery management should be more accurate. in order to continuously improve the level of spatial scientific management of marine fisheries in China.
Evaluation of suitable body size for tagging and releasing of yellowfin seabream (Acanthopagrus latus)
LÜ Shaoliang, LIN Kun, ZENG Jiawei, ZHANG Shenzeng, CHEN Zhijie, WANG Xuefeng
In Press  doi: 10.11964/jfc.20200412224
[Abstract](668) [FullText HTML](312) [PDF 5862KB](22)
The data obtained by tag-recapture method are commonly used to evaluate the fish population dynamics and the effect of stock enhancement. However, to ensure the accuracy of the recapture data, it is necessary to choose the appropriate fish size for tagging. Acanthopagrus latus was employed to conducted two indoor experiments. In the first experiment, the effects of T-bar anchor tags on growth, survival and tag retention of A. latus from four size groups (average body length: 5 cm, 7 cm, 11 cm, and 14 cm, respectively) were examined and the size-dependent effects on survival and tag retention were tested. In the second experiment, different mix ratios of tagged fish and untagged fish from two size groups (average body length: 7 cm and 14 cm, respectively) were set for simulated catching and the catching results were resampled. The differences in catching results between groups were compared, the differences between catching result and resample result were also compared. The results show that: ① there was no significant difference in the specific growth rate between 7 cm, 11 cm and 14 cm groups. ② the survival rate was size-dependent. All the tagged fish of 5 cm group died in the first week after tagging. The survival rate of other size groups was 77.5%, 92.5% and 100%, respectively. The relational expression of logistic regression between body length and the probability of survival was: P=exp(0.099X-6.900)/[1+exp(0.099X-6.900)]. ③ the tag retention rate was high (97.5% in 7 cm group, 100% in 11 cm and 14 cm group) but seemed to be unrelated with fish size. ④ there was no significant effect of fish size on the catching result and the resampling result but significant effect of mix ratio of tagged and untagged fish on it. In summary, it is recommended that study objectives and cost should be considered when choosing the appropriate fish size for tagging stocking fishes like A. latus. If the probability of survival needs to be >50%, the tagged individuals with body length should be >7 cm. If >75%, the body length should be >8 cm. If >95%, the body length should be >10 cm. And it is worth further study to know about the appropriate proportion of tagged fish for tagging and releasing.
Effects of Chaetoceros muelleri and Rhodotorula sp. on the development, growth and survival of the planktonic larvae of sea cucumber (Holothuria leucospilota)
YU Zonghe, HUANG Wen, MA Wengang, HUO Da, LIU Wenguang, XU Qiang
Accepted Manuscript  doi: 10.11964/jfc.20200512277
[Abstract](578) [FullText HTML](247) [PDF 5967KB](18)
The sea cucumber Holothuria leucospilota is an edible sea cucumber species, which is widely distributed in the shallow water of tropical and subtropical Indo-Pacific Ocean. Nowdays, the H. leucospilota has become an important fishery resource owing to the continuously increasing market demand, however, overfishing activities will put this species at risk of extinction in the future. Artificial breeding of H. leucospilota is considered as a useful strategy to solve this problem. The use of suitable substitute diets is an economical and efficient approach for breeding of planktonic larvae of sea cucumbers. In this study, the microalgae Chaetoceros muelleri and Rhodotorula sp. were fed to planktonic larvae of sea cucumber H. leucospilota, either singly or in combination, to evaluate their nutritional quality. The C. muelleri and Rhodotorula sp. were mixed in 4: 0, 3: 1, 2: 2, 1: 3 and 0: 4, by volume, and they were labeled as groups A, B, C, D and E, respectively. Results showed that larvae in group A, which fed solely on C. muelleri, exhibited the fastest growth and development among the five groups, larvae could develop to the auricularia stage on the 10th day and the doliolaria stage on the 18th day; meanwhile, survival of the larvae in group A was the highest, and the survival rate in this group was 58.73%±2.75% at the end of the experiment. By contrast, the larvae in groups D and E always stayed in the early auricularia stage, and individuals in these two groups could not form the hyaline spheres during the whole study period. The larvae in group E exhibited a negative growth during the whole study period, and survival rate of this group was only 22.22% ± 5.50% at the end of the experiment. In general, negative effects on the development, growth and survival of the planktonic larvae of H. leucospilota were found with the increase in the proportion of the Rhodotorula sp. in the diet, and therefore Rhodotorula sp. was not a suitable substitute diet for breeding of H. leucospilota.
Guiding out-migrating juvenile grass carp Ctenopharyngodon idella by pulsed direct current electricity with different electric parameters at different flow velocities
SHI Xunlei, HU Cheng, DA Wa, NI Ma, WANG Qingfu, SHI Xiaotao, LIU Guoyong
Accepted Manuscript  doi: 10.11964/jfc.20200712354
[Abstract](619) [FullText HTML](257) [PDF 6270KB](11)
The necessity for fish to migrate safely is a key requirement for the existence of many fish populations. Anthropogenic constructions, such as dams and weirs, that block rivers make it difficult, if not impossible, for fish to reach their upriver spawning grounds. Also, these constructions are also very dangerous for fish moving down the river because dams are built associated with hydroelectric power station plant intakes where fish are injured or killed on the gratings, pump screens, and in turbine chambers. Mild fields of pulsed, direct current (DC) electricity have been used extensively in deterring invasive fish species as well as in reservoir fishery, but directional fish guidance using electric deterrence arrays to guide fish toward desirable passage locations or away from dangerous areas has received little attention. The effectiveness of the electric barriers is quite variable and testing is often lacking for a variety of water velocity conditions. To explore the effects of different electric parameters of electrical barriers on the avoidance behavior of the juvenile grass carp C. idella with body length of (10.22±2.01) cm and body mass of (34.25±3.62) g, a double-row type of electrical barrier based on pulsed direct current electricity was established and orthogonal designed experiment of three factors, including pulse voltage, frequency and width, four levels was adopted to optimize the blocking performance of the electrical barrier under the static water condition. To explore the effects of water flow conditions on the blocking efficiency of electric barriers using the optimized electric parameters recommended for static water conditions, three flow conditions at a generalized model of fishway entrance were utilized to test the attractive efficiency of fishway entrance. The results showed that, under static water conditions, the working condition 7 had the highest blocking rate (88.67±1.10)% and lower average stupefaction rate and that the factors affecting blocking efficiency are pulse voltage, pulse frequency and pulse width respectively. Determined by analysis of variance and multiple comparison, the optimal electric parameters under static water conditions for blocking efficiency were the pulse voltage of 160 v/m, the pulse frequency of 6 Hz and the pulse width of 16 ms. Under the optimal electric parameters, the experimental fish had minimal injuries when subjected to electric barriers. By employing the optimum electric parameters recommended for static water conditions, the active electric barrier can dramatically boost the aggregation rate and average retention time ratio at the fishway entrance when the channel velocity was 0.15 m/s. When the channel velocity was 0.25 m/s and 0.35 m/s, the aggregation rate and average retention time ratio with the active electric barrier were not enhanced significantly than that in the inactive electric barrier. Therefore, the recommended electric conditions for optimal blocking effect is to set the pulse voltage of 160 v/m, the pulse frequency of 6 Hz and the pulse width of 16 ms under static conditons. The attractive effects of fishway entrance could be enhanced by the active electrical barriers with the best flowing water velocity being 0.15 m/s. These results will have important reference significance for the practical engineering of the electrical barrier arrangement. The pulsed direct current electric systems have the potential to improve fish passage at anthropogenic barriers. Additional research should investigate the effectiveness under variable electric field voltage and various water flow velocities for fish of various size and shape depending on the species and its ethology.
Effect of dietary choline level on growth performance, body composition and serum antioxidant activity of juvenile largemouth bass (Micropterus salmoides)
ZHOU Yue, WANG Weilong, LI Songlin, LYU Hongyu, ZHANG Song, CHEN Naisong, HUANG Xuxiong
Accepted Manuscript  doi: 10.11964/jfc.20200812380
[Abstract](819) [FullText HTML](372) [PDF 6523KB](58)
An experiment was conducted to investigate the effects of dietary choline content on growth performance, body composition, and serum antioxidant activity of juvenile largemouth bass, Micropterus salmoides. Graded choline chloride levels of 0, 700, 1 400, 2 100 and 2 800 mg/kg were supplemented to basal diet to formulate five isonitrogen and isoenergy practical diets containing choline of 2 369.57 (control group), 2 716.90, 2 993.49, 3 443.60 and 3 799.05 mg/kg, respectively. Each diet was randomly assigned to triplicate cages of 20 fish with an initial average weight of (20.00±0.10) g for 56 days. The results showed that the weight gain rate (WGR) and specific growth rate (SGR) of the fish first increased and then decreased with the increase of dietary choline chloride, and reached the maximum when the dietary supplementation was 2 100 mg/kg, which were significantly higher than those of the control group. The survival rate (SR), hepatopancreas somatic index (HSI), viscera somatic index (VSI), and condition factor (CF) of the fish were not significantly affected by dietary choline chloride supplementation. When the dietary choline chloride supplementation reached 2 100 mg/kg or above, the lipid contents in muscle and liver of the fish were significantly decreased than those in control. Compared with the control group, the total antioxidant capacity, superoxide dismutase and catalase activities were significantly increased and the content of malondialdehyde in serum was significantly decreased in the groups which were dietary supplemented 1 400 mg/kg, 2 100 mg/kg and 2 800 mg/kg choline chloride. The maximum of lysozyme activity and minimum of aspartate aminotransferase activity appeared in the group treated with dietary choline chloride of 2 100 mg/kg the dosage was, which were significantly different from those of the control group. All these results indicated that the suitable dietary choline chloride supplementation could significantly improve growth performance, reduce liver fat content, and enhance the serum's antioxidant capacity. Regression analysis showed that the recommended amount of choline chloride in the practical diet of juvenile largemouth bass was 2 008.50 ~ 2 398.16 mg/kg (the dietary choline content was 3 432.09 ~ 3 530.23 mg/kg).
Characteristics of formation related genes (PyMFG) of monospores and analysis of differential expression in Pyropia yezoensis
SONG Shanshan, DING Hongchang, YAN Xinghong
In Press  doi: 10.11964/jfc.20190311710
[Abstract](1147) [FullText HTML](394) [PDF 2804KB](30)
In our study, a complete open reading frame of PyMFG was obtained by RT-PCR based on the sequence of differentially expressed genes (Contig-21827) screened by transcriptome sequencing of Pyropia yezoensis. Sequence analysis showed that the ORF of the PyMFG was 1 224 bp in length and encoded a polypeptide fragment of 407 amino acids with a molecular weight of 46.24 ku, and theoretical pI of 9.08. Domain analysis revealed that the protein contains a conserved TEA domain and a YAP domain, which belongs to the TEA-ATTS superfamily domain. We found that the protein and fungal conidia forming proteins clustered into one large branch with close genetic relationship through multiple sequence alignment and phylogenetic analysis. In addition, the comparison of the ability of releasing monospores and qRT-PCR analysis between different strains indicated that the expression trend of PyMFG in PY26W and PY26W' was highly consistent with macroscopic statistical results, while the trend in PY26R and PY26R' were exactly existed difference. By inference, the gene type and molecular mechanism regulating the formation and release of monospores in the parental (PY26W) and partial parental strain (PY26W') and the female parental (PY26R) as well as partial female strain (PY26R') existed certain difference, leading to the divergence between the macroscopic statistical results of monospores and the qRT-PCR results.
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2021, 45(10): 1-1.  
[Abstract](0) [FullText HTML](0) [PDF 10630KB](0)
2021, (10): 1-2.  
[Abstract](0) [FullText HTML](0) [PDF 221KB](0)
Comparison of nutritional quality and volatile flavor compounds in muscle of Culter alburnus cultivated in in-pond “raceway” aquaculture system and traditional pond
CAI Li, WEI Zehong, TANG Tao, LIU Shaojun, MAI Kangsen
2021, 45(10): 1621-1633.   doi: 10.11964/jfc.20210412770
[Abstract](141) [FullText HTML](73) [PDF 4802KB](10)
In the past several decades, the rapid development of aquaculture has brought many environmental problems. The waste discharged from aquaculture may lead to eutrophication and deterioration of water quality, which will further affect the growth and health of aquatic animals. A new aquaculture model is emerging to deal with this problem, named in-pond “raceway” aquaculture system. Based on that, a comparative study on the nutritional value and volatile flavor compounds profile in muscle of Culter alburnus was conducted to investigate the difference between in-pond “raceway” aquaculture system and traditional pond culture. Amino acids analyzer, high performance liquid chromatography (HPLC) and gas chromatograph-ion mobility spectrometer (GC-IMS) were used to identify and analyze the profile of amino acids, fatty acids and volatile flavor compounds in the muscle under different culture conditions. The fingerprint spectra of volatile flavor compounds were established. There was no significant difference in the content of crude protein and crude lipid of muscle between the two groups. The content of essential amino acids [EAA, (8.54±0.01) g/100 g wet basis] and total amino acids [TAA, (17.36±0.00) g/100 g wet basis] of muscle in the in-pond “raceway” group was significantly increased. Additionally, a total of 23 volatile flavor compounds were screened from the C. alburnus muscle from the two groups. Compared with the traditional pond culture group, the contents of butanal, 3-methylbutanal, 2-methylbutanal, pentanal, heptanal, benzaldehyde, octanal, nonanal, 2-butanone, 3-hydroxy-2-butanone and ethanol were decreased, while the contents of 2-heptanone, 1-hexanol and 1-octen-3-ol were increased in the in-pond “raceway” aquaculture system group. At the same time, compared with traditional pond culture group, the volatile flavor of the in-pond “raceway” aquaculture system group improved due to the decrease of some unpleasant volatile flavor compounds. C. alburnus cultivated in the in-pond “raceway” aquaculture system improved the amino acid and flavor characteristics and kept the muscle approximate composition unchanged. The above results provide basic data for the evaluation of the flesh quality of C. alburnus of the in-pond “raceway” aquaculture system, which indicates that this model has great potential for improvement of fish quality.
Effects of temperature and feeding rate on postprandial metabolic response in juvenile Percocypris pingi
PU Deyong, DING Yuxiao, LIU Xiaohong, PU Yingmei, GU Haoran, HE Xingheng, WU Yi, WANG Zhijian
2021, 45(10): 1634-1641.   doi: 10.11964/jfc.20200912390
[Abstract](251) [FullText HTML](86) [PDF 7726KB](7)
The marked increase in the metabolic rate that occurs following feeding is commonly referred to as specific dynamic action (SDA). Previous studies on SDA in animals have found that the meal type, temperature, body size, feeding frequency, fasting and feeding rate all have significant effects on SDA. The study of postprandial metabolic response in Percocypris pingi has not been reported. To investigate the effects of temperature and feeding rate on postprandial metabolic traits in juvenile P. pingi, the experimental fish [body weight: (38.35±0.49) g, body length: (14.22±0.10) cm] were fed with loach (Misgurnus anguillicaudatus) (feeding rates: 1%, 2%, 4% body mass at 15 °C; 1%, 2%, 4% and 6% body mass at 25 °C) for 4 weeks as diet acclimation at 15 °C and 25 °C in indoor recirculating aquaculture systems. After that, the oxygen consumption rate was detected and parameters related to postprandial metabolic response were calculated. Results showed that at the same feeding rate, resting metabolic rate, peak metabolic rate, total energy expenditure on SDA and SDA coefficient of 25 °C acclimation group were significantly higher than those of 15 °C acclimation group. The SDA duration of 25 °C acclimation group at 2% and 4% feeding rate was significantly shorter than that of 15 °C acclimation group. At the 25 °C, fish of higher feeding rates (4% and 6%) presented significantly higher peak metabolic rate, factorial metabolic scope, SDA duration and total energy expenditure on SDA than those of lower feeding rates (1% and 2%) at 25 °C, and times to peak metabolic rate of 4% and 6% feeding rates were significantly earlier than that of 1% and 2% feeding rates as well. However, the SDA coefficient showed an opposite situation: higher feeding rate presented significantly lower values. At the 15 °C, peak metabolic rate, factorial metabolic scope, SDA duration and energy expended on SDA of 4% feeding rate group were significantly higher than those of 1% and 2% feeding rates. Nevertheless, no significant difference in the time to peak metabolic rate and the SDA coefficient among all feeding rates were observed at 15 °C. All the above information suggested that the water temperature of 25 °C is more beneficial to the rapid food digestion and absorption by juvenile P. pingi; and the fish may meet the increased energy demand during digestive process by means of increasing peak metabolic rate and prolonging SDA duration with the increase of feeding rate. The results of this study may provide important reference data for the breeding practice and species protection of P. pingi.
Effects of Schizochytrium sp. oil combined with exogenous EPA on fatty acid composition, FAD and ELO gene expression and lipid metabolism of juvenile Ctenopharygodon idella
XING Junxia, JI Hong, LI Handong, XIAO Fenfen, YUAN Xiangtong
2021, 45(10): 1642-1656.   doi: 10.11964/jfc.20200912417
[Abstract](122) [FullText HTML](55) [PDF 2721KB](5)
The grass carp (Ctenopharyngodon idella) dietary Schizochytrium sp. stearin oil may show better growth performance than dietary fish oil by saving energy required for de novo synthesis of DHA, promoting lipolysis energy supply and inhibiting protein catabolism. The purpose of this study was to investigate whether DHA-rich Schizochytrium sp. stearin oil needs to be compatible with EPA and its possible mechanism. Equipped with five groups of iso-nitrogen and isoenergetic diets and fed grass carp (22.70 g±0.80 g) for 49 d. The 0.52% n-3 long-chain polyunsaturated fatty acid (LC PUFA) of the diets were provided with fish oil (F-O); Sc stearin oil (S-O); stearin oil (DHA)∶EPA =3∶2 (SE1-O); stearin oil (DHA)∶EPA = 1∶1(SE2-O); EPA (E-O), respectively. The results showed: 1) There was no difference in the weight gain rate (WG), specific growth rate (SGR) and feed conversion ratio (FCR) among all the groups; 2) The content of crude protein in muscle of S-O group was significantly higher than those of E-O group; 3) the content of DHA in muscle of S-O group was significantly higher than that of F-O group, SE1-O group and E-O group; 4) there was no significant difference in atherogenicity index among the groups, the thrombogenicity index of SE2-O group was significantly higher than that of F-O group, the hypocholesterolemic/ Hypercholesterolemic ratio in S-O group and SE2-O group was markedly lower than those in F-O group; 5) the adipose size of intraperitoneal fat in E-O group was notably higher than those in F-O group and SE1-O group, the adipose TAG lipase(ATGL)and carnitine palmitoyltransferase 1(CPT1) mRNA levels in E-O group were apparently down-regulated; in muscle, the fatty acid desaturase (FAD)mRNA level was markedly higher in E-O group than that in S-O group, the fatty acid elongase(ELO)mRNA level was obviously down-regulated in S-O group. Studies have shown that the use of Sc oil alone or in combination with EPA had no significant effect on growth, n-3LC PUFA content and lipid hydrolysis of adipose tissue of grass carp. When EPA was the sole source of n-3LC PUFA, the lipid hydrolysis of adipose tissue was reduced and the content of crude protein in muscle was reduced. High level of DHA in the diet would weaken the body's ability to synthesize LC PUFA. Compared to EPA, grass carp may need DHA more, and the Sc oil could be used alone in the feed of grass carp without combination with EPA.
PGC1α molecular characterization and its responsiveness to nutrient restriction, carbohydrate-enriched diets and glucose loadings in blunt snout bream (Megalobrama amblycephala)
DING Zhirong, LI Xiangfei, LIU Wenbin, XIE Dizhi, XU Chao, Jean-Jacques Yao Adjoumani
2021, 45(10): 1657-1666.   doi: 10.11964/jfc.20201212543
[Abstract](151) [FullText HTML](43) [PDF 3030KB](3)
To explore the mechanism of peroxisome proliferator activated receptor γ coactivator 1α (PGC1α) in the glucose metabolism of blunt snout bream Megalobrama amblycephala, the partial cDNA of PGC1α was cloned, and the transcriptional response of this gene to nutrient restriction, carbohydrate-enriched diets and glucose loadings were investigated. The partial cDNA was 2566 bp with an open reading frame of 1 404 bp encoding 467 amino acids, and compared to Ctenopharyngodon idellus, it showed 96.79% homology. The mRNA levels of PGC1α in the brain and liver were significantly increased during 10 days of fasting, and then decreased to normal level after refeeding 1 h. The high-carbohydrate diet significantly decreased the mRNA levels of PGC1α in the brain and liver. In addition, the mRNA levels of PGC1α in the brain and liver both decreased significantly during the first 2 h, then returned to the basal value at 12 h. The results indicated that PGC1α plays an important role in glucose metabolism in M. amblycephala. The results obtained here will provide the theoretical foundation for completing the research of PGC1α functions involving the regulation of glucose homeostasis in fish.
Effects of different water temperature and dietary phosphorus levels on the production performance, tissue and water phosphorus content of Macrobrachium nipponense
SUN Miao, HE Chaofan, ZHANG Ling, JIANG Guangzhen, LIU Wenbin, LI Xiangfei
2021, 45(10): 1667-1676.   doi: 10.11964/jfc.20201212554
[Abstract](238) [FullText HTML](102) [PDF 2630KB](9)
Water temperature and dietary phosphorus levels are crucial for the growth of crustaceans. However, the interactions between both factors are still poorly understood in crustacean culture, which brings difficulties in advancing the feed utilization. This experiment was conducted to explore the effects of different temperature and dietary phosphorus levels on the production performance, tissue and water phosphorus content of M. nipponense. Using a 3×3 factorial design, nine groups (respectively named 20/1.1, 20/1.5, 20/1.9, 25/1.1, 25/1.5, 25/1.9, 30/1.1, 30/1.5, 30/1.9) were formed, including three water temperature (20, 25 and 30 °C) and three dietary phosphorus levels (1.1%, 1.5% and 1.9%). Each diet was tested by 4 replicates. Prawns were reared in the indoor circulation systems for 8 weeks. The results showed that, in terms of water temperature, the final body weight (FBW), specific growth rate (SGR) and weight gain rate (WGR) of the 30 °C group were all significantly higher than those of the 20 °C, but showed no statistical difference with those of the 25 °C. However, the opposite was true for feed intake and feed conversion rate (FCR). In addition, the phosphorus retention efficiency (PRE) and hemolymph phosphorus levels of the 30 °C group were both significantly higher than those of the other two groups, meanwhile the hemolymph phosphorus level of this group was significantly higher than that of the 25 °C group, but showed no significant difference with the 20 °C group. In terms of dietary phosphorus levels, the FBW, WGR, PRE and hemolymph calcium level of the 1.9% phosphorus level group were all significantly lower than those of the other groups, while phosphorus intake and FCR showed the opposite trend. The SGR of the 1.9%phosphorus level group was significantly lower than that of the 1.5% group, but showed no statistical difference with that of the 1.1% group. Besides, the whole-body phosphorus contents of the 1.1% group was significantly lower than that of the other groups, and the hemolymph calcium content of this group was significantly higher than that of the 1.9% group, but there was no significant difference with the 1.5% group. Serum alkaline phosphatase (AKP) activities of the 1.5% group was significantly higher than that of the 1.1% group, but showed no statistical difference with those of the1.9% group. Furthermore, feed intake, phosphorus intake, PRE, hemolymph phosphorus level and AKP activities were all significantly affected by the interaction between water temperature and dietary phosphorus level with the maximized values observed in the 20/1.1, 25/1.9 and 30/1.9, 30/1.1, 30/1.9, 25/1.5 group, respectively. Additionally, water phosphorus levels increased significantly with increasing sampling time, while the water phosphorus level of the 20/1.5 group was significantly higher than those of the 25/1.1 and 30/1.1 groups. Overall, M. nipponense in the 30/1.1 group obtained the best growth performance and feed efficiency coupled with low phosphorus emission.
Influence of dietary calcium to phosphorus ratio on growth, minerals bioaccumulation and energy metabolism in juvenile swimming crab (Portunus trituberculatus)
ZHAO Mingming, YUAN Ye, JIN Min, LUO Jiaxiang, WANG Xuexi, HU Xiaoying, CHENG Xin, SHI Bo, JIAO Lefei, ZHOU Qicun
2021, 45(10): 1677-1691.   doi: 10.11964/jfc.20201212536
[Abstract](137) [FullText HTML](46) [PDF 3617KB](0)
An 8-weeks feeding trial was conducted to investigate the effects of dietary calcium/phosphorus ratios on the growth performance, minerals bioaccumulation, and energy metabolism in juvenile swimming crab (Portunus trituberculatus). Five semi-purified experimental diets were formulated to contain different ratios of calcium to phosphorus (1.00∶2.00, 1.00∶1.50, 1.00∶1.00, 1.00∶0.75 and 1.00∶0.50, respectively). A total of 150 swimming crab juveniles [initial weight (12.82 ± 0.37) g] were randomly allocated into five groups with three replicates, each and consisted of 30 crabs. The results indicated that crabs fed the diets with calcium to phosphorus ratios of 1.00∶1.00 and 1.00∶0.75 had significantly higher specific growth rate (SGR) and feed efficiency (FE) than those fed the other diets. The highest activity of GOT in hemolymph was observed at crabs fed the diet with calcium to phosphorus ratio of 1.00∶0.50, and AKP and GPT exhibited an increasing trend with the increase of dietary calcium to phosphorus ratios. Moreover, the content of phosphorus in tissues significantly increased with dietary calcium to phosphorus ratios decreasing from 1.00∶0.50 to 1.00∶2.00. Furthermore, the highest ATP content in hepatopancreas was observed in crab fed the diets calcium/phosphorus ratios of 1.00∶1.50 and 1.00∶1.00. The activities of enzymes such as hexokinase (HK) and succinate dehydrogenase (SDH) related to energy metabolism were significantly higher in hepatopancreas of crabs fed the diet with calcium to phosphorus ratio of 1.00∶1.00. Crabs fed the diet containing calcium to phosphorus ratio 1.00∶1.00 also showed significantly higher expression of genes involved in electron transport chain complex, such as nd1, sdhc, cytb and cox Ⅱ than those fed the other diets. The genes related to mitochondrial energetic metabolisms, such as atpase6, sirt3, and nrf1 were significantly up-regulated in crabs fed the diet with calcium and phosphorus ratio of 1.00∶0.75. Overall, based on broken-line and quadratic regression analysis between PWG against dietary calcium to phosphorus ratios, the optimal dietary calcium to phosphorus ratio was estimated to be 1.06-1.26, and this range could be recommended to maintain optimal phosphorus bioaccumulation and promote energy production for juvenile swimming crab.
Dietary arginine requirement and effects of dietary arginine levels on the metabolism of Scophthalmus maximus
FU Fengshun, LIU Chengdong, WANG Xuan, ZHOU Huihui, MAI Kangsen, HE Gen
2021, 45(10): 1692-1702.   doi: 10.11964/jfc.20210312693
[Abstract](208) [FullText HTML](84) [PDF 2561KB](9)
The purpose of this study was to investigate the arginine requirement and effects of dietary arginine levels on the growth and metabolism of turbot (Scophthalmus maximus). Turbots with an initial body weight of (43.07±0.10) g were selected as the research object. Five isonitrogenous and isolipid diets (51% crude protein and 12.5% crude lipid) were formulated with casein and gelatin as the main protein sources and fish oil and soybean lecithin as the lipid sources. The arginine contents of the diets were 1.92%, 2.65%, 3.40%, 4.17% and 4.88% of dry matter by adding crystalline amino acid mixture, respectively. (The corresponding diet number was 1, 2, 3, 4 and 5, respectively). The group fed 1.92% arginine level diet served as control group. Each treatment was set to 3 replicates, each containing 12 fish, and the breeding period was 10 weeks. The results showed that 3.40% to 4.88% arginine (6.66% to 9.52% of dietary protein) significantly improved the growth performance and feed utilization of turbot compared with the control group. According to the broken line regression analysis based on specific growth rate (SGR), the optimal dietary arginine requirement of turbot was estimated to be 3.17% of dry matter (6.21% of dietary protein). Appropriate dietary arginine levels significantly increased body protein content and plasma total protein level, while significantly decreased plasma glucose level. In addition, appropriate dietary arginine levels significantly enhanced the expression of genes related to fatty acid synthesis, fatty acid β-oxidation, glycolysis, tricarboxylic acid (TCA) cycle and oxidative phosphorylation, while significantly decreased the expression of genes associated with amino acid degradation in liver. The results demonstrated that 3.40% to 4.88% arginine (6.66% to 9.52% of dietary protein) can regulate the nutrient metabolism and promote the growth of turbot.
Effects of cottonseed protein source on growth, body composition and health of Micropterus salmoides
ZHOU Xingmei, HE Guanglun, XU Zhicheng, CHEN Yongjun, TAN Beiping, LIN Shimei
2021, 45(10): 1703-1714.   doi: 10.11964/jfc.20210412748
[Abstract](127) [FullText HTML](75) [PDF 3238KB](4)
To evaluate the feasibility of cottonseed protein in largemouth bass (Micropterus salmoides) diet, five isonitrogen-isolipid experimental diets (CPC0 as control group, CPC1, CPC2, CPC3, and CPC4) were prepared by replacing 30% fish meal with 4 cottonseed proteins of different quality. Micropterus salmoides [average body weight (12.20±0.11) g] were fed in indoor circulating culture system for 8 weeks. The results showed that the nutrient composition, contents of gossypol, raffinose and stysaccharide of the four kinds of cottonseed proteins were different, and CPC3 cottonseed protein quality was the best. The final body weight, weight gain rate and specific growth rate of CPC3 group were significantly higher than those of the other groups, but there were no significant difference in the routine nutrients and muscle amino acid nutritional composition among all groups. The activities of SOD and GSH-Px and the mRNA expressions of CAT and SOD in liver of CPC3 group were the highest, while the content of MDA was the lowest. The relative expressions of anti-inflammatory factors IL-10 and TGF-β were the highest in CPC3 group, while the relative expressions of pro-inflammatory factors IL-1β, IL-8 and TNF-α were the lowest in CPC3 group. In addition, cottonseed protein sources could significantly affect the liver protein metabolism of largemouth bass, and the activities of ALT and AST and the expression levels of P13K, Akt, m-TOR, S6K1 and 4E-BP in CPC3 group were the highest. Meanwhile, it was found that CPC3 group had the highest intestinal T-SOD enzyme activity, the lowest MDA content, and the lowest intestinal permeability indexes (diamine oxidase, D-lactic acid and endotoxin). Cottonseed protein sources also affected the expression of tight junction protein-related genes ZO-1, Claudin-1 and Occludin in the intestine. The results showed that different cottonseed protein quality had different effects on the growth and health of M. salmoides, among which cottonseed protein CPC3 showed the best effect and significantly improved the liver and intestinal health of M. salmoides, thereby promoting the growth of M. salmoides. Cottonseed protein CPC3 can be used as a good protein source for M. salmoides feed.
Dietary zinc requirement of juvenile largemouth bass (Micropterus salmoides)
SONG Bowen, YANG Hang, LI Xiaoqin, WANG Pu, HE Ming, XU Zhen, YANG Pinxian, LENG Xiangjun
2021, 45(10): 1715-1725.   doi: 10.11964/jfc.20200912393
[Abstract](130) [FullText HTML](62) [PDF 2970KB](4)
To determine the dietary zinc requirement of juvenile largemouth bass (Micropterus salmoides), casein, gelatin and fish meal were used as the main protein sources and ZnSO4·H2O as zinc source to produce a semi-purified diet. Then, zinc was added into the basal diet at levels of 0, 25, 50, 100 and 200 mg/kg, to obtain five diets containing zinc of 24.8, 48.8, 78.9, 126.1 and 223.6 mg/kg dry matter, respectively. Largemouth bass with initial body mass of (10.99±0.07) g were fed one of the five diets for 8 weeks. The results showed that the supplementation of 25 mg/kg Zn significantly increased the weight gain rate (WGR), and reduced feed coefficient ratio (FCR) of largemouth bass, which tended to stabilize when higher levels of Zn were added. When dietary Zn reached 25-49 mg/kg, the serum activity of CuZn-SOD and T-SOD remained stable, while Zn-79 group showed the highest AKP activity. The zinc content in whole fish and vertebrae increased with the increasing dietary Zn, and showed no significant increase when dietary Zn content was higher than 126 mg/kg (Zn-126 group). The iron content in whole body, iron and manganese contents in vertebra, and the retention of iron and zinc in whole body decreased with the increasing dietary Zn. In conclusion, the supplementation of Zn in diet improved the weight gain and feed utilization, promoted serum immunity and Zn deposit in whole body and vertebra. Based on the WGR, FCR, whole body zinc and vertebra zinc, the broken-line analysis indicated that the dietary requirement of Zn was 45.5, 44.6, 121.8 and 130.5 mg/kg dry matter, respectively.
Effects of dietary zinc on growth, serum non-specific immune indexes, disease resistance and intestinal flora structure in juvenile Litopenaeus vannamei
HE Shuqing, LI Rimei, YANG Qihui, TAN Beiping, DONG Xiaohui, CHI Shuyan, ZHANG Shuang, LIU Hongyu
2021, 45(10): 1726-1739.   doi: 10.11964/jfc.20200712355
[Abstract](182) [FullText HTML](75) [PDF 3230KB](7)
The trial was conducted to study the effects of dietary zinc (Zn) on growth, non-specific immune indexes, disease resistance and intestinal flora structure in juvenile Litopenaeus vannamei. Zinc sulfate heptahydrate (ZnSO4·7H2O) was used as the Zn source in this experiment. The healthy prawns [initial body weight (0.45±0.01) g] were fed diets (isonitrogenous and isolipid) containing available Zn levels (i.e., 0, 20, 40, 60, 80, 100, and 150 mg/kg) for 8 weeks, respectively. The results showed that: ① The weight gain rate (WGR) and specific growth rate (SGR) in the 60 mg/kg group were significantly higher than those in the control group, and the best feed conversion rate (FCR), the optimal protein efficiency ratio (PER) and survival rate (SR) were found in 80 mg/kg group.② The crude lipid (CL) contents in 80-150 mg/kg groups were significantly higher than that in control group, and the contents of crude ash (CA) in 40-80 mg/kg groups were significantly higher than that in control group.③ The contents of serum total protein (TP), total cholesterol (TC) and triglyceride (TG) in Zn supplemented groups were significantly higher than those in control group. ④ Dietary Zn supplement increased the activities of serum superoxide dismutase (SOD), phenol oxidase (PO), alkaline phosphatase (AKP) and acid phosphatase (ACP) and total antioxidant capacity (T-AOC), and significantly decreased the content of malondialdehyde (MDA) in serum, indicating that Zn could improve the non-specific immunity of L. vannamei.⑤ In the experiment of artificial acute infection with Vibrio harveyi, the survival rate of shrimp increased firstly and then decreased with the increase of Zn levels. The survival rate in Zn supplemented group was significantly higher than that in control group, and the highest survival rate and disease resistance were found in 80 mg/kg group. ⑥ In the analysis of intestinal flora, the numbers of effective OTUs in 40 mg/kg and 100 mg/kg groups were significantly higher than that in control group. With the increase of dietary Zn, the Ace index and Chao1 index increased significantly, while the Shannon index and Simpson index had no significant changes. The results showed that an optimal level of Zn could promote the growth and improve the disease resistance of juvenile L. vannamei. The growth performance and disease resistance of L. vannamei were poor when Zn was deficient in diets, while excessive Zn level inhibited the growth of L. vannamei to a certain extent. Overall, based on the WGR, the growth performance of L. vannamei was significantly improved by supplementing 94.46 mg/kg Zn to the diets. Based on the evaluation of disease resistance, the optimal dietary Zn supplement of L. vannamei was 80 mg/kg.
Effects of dietary sodium deoxycholate on the growth, glucose metabolism and intestinal microbiota of largemouth bass (Micropterus salmoides)
ZHOU Nannan, DING Feifei, ZHANG Le, QIAO Fang, DU Zhenyu, ZHANG Meiling
2021, 45(10): 1740-1752.   doi: 10.11964/jfc.20210312665
[Abstract](182) [FullText HTML](65) [PDF 6315KB](8)
Bile acids play an important role in glucose metabolism, lipid metabolism, and they can also help to maintain the liver health and intestinal homeostasis in animals. In recent years, bile acids have been widely used as new additives in aquatic feeds. However, so far, most of the bile acid products used in aquaculture are mixed bile acids. There are many different kinds of bile acids, and different bile acids have different effects on the growth and metabolism of fish. Therefore, it is necessary to evaluate the effects of different bile acids on fish growth and metabolism to select the appropriate type of bile acids for precise nutritional regulation. This experiment was conducted to evaluate the effect of sodium deoxycholate as a feed additive on Micropterus salmoides. Two experimental diets were formulated to contain different sodium deoxycholate levels of 0, and 300 mg/kg referred to as CON and SD, respectively. The effects of sodium deoxycholate on the growth condition, metabolic characteristics and intestinal microbiota were analyzed. M. salmoides (10.80 ± 0.12) g were cultured for 8 weeks. The results showed that sodium deoxycholate significantly increased the final body weight [(37.24 ± 0.64) g in the control group and (46.87 ± 1.44) g in the sodium deoxycholate group]. The body length was (12.42 ± 0.12) cm in the control group and (13.07 ± 0.14) cm in sodium deoxycholate group. The condition factor (CF) was (1.95 ± 0.06) g/cm3 in the control group and (2.09 ± 0.03) g/cm3 in the sodium deoxycholate group, but there was no significant difference in viscera index (VSI) or hepatosomatic index (HSI). Sodium deoxycholate had no effect on the total lipid and crude protein of whole fish. Sodium deoxycholate significant increased the expression level of gluconeogenesis-related and glycolysis-related genes in liver and muscle, and the sodium deoxycholate promoted the glycogen accumulation in muscle [(0.31 ± 0.03) mg/g in control group and (0.46 ± 0.03) mg/g in sodium deoxycholate group] by increasing the activity of glycogen synthase, but there was no significant difference in the liver glycogen content between these two groups. In addition, sodium deoxycholate significantly increased bile acids content in gallbladder [(199.4 ± 12.72) μmol/L in control group, (341.1 ± 8.52) μmol/L in sodium deoxycholate group]. Our results indicated that sodium deoxycholate can promote the bile acid synthesis mainly by down-regulating the expression level of fxr gene and up-regulating the expression level of cyp7a1 gene in the liver. The abundance of Firmicutes and Bacteroidetes decreased while Actinobacteria increased in M. salmodides fed with sodium deoxycholate at the phylum level. All these results suggested that sodium deoxycholate can be used as a feed additive for M. salmodides to promote the growth condition, and increase muscle glycogen accumulation and bile acid synthesis.
Effects of dietary Bacillus subtilis HGcc-1 on gut and liver health, serum complement and gut microbiota of common carp fingerlings (Cyprinus carpio)
HU Juan, GAO Chenchen, YAO Yuanyuan, HAO Qiang, ZHOU Wei, RAN Chao, ZHOU Zhigang, YANG Yalin, ZHANG Zhen
2021, 45(10): 1753-1763.   doi: 10.11964/jfc.20210312697
[Abstract](107) [FullText HTML](69) [PDF 2873KB](7)
In order to study the effects of Bacillus subtilis HGcc-1 on the gut and liver health, serum complement and gut microbiota of Cyprinus carpio fingerlings, healthy C. carpio fingerlings with a body weight of (13.10±0.39) g were selected, and randomly divided into HGcc-1 supplementation group and control group, and after 20 weeks of feeding, the growth indicators were measured, and the C. carpio serum endotoxin (LPS), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), total complement and lysozyme were detected, and 16S rRNA sequencing of the gut microbiota was made. At the same time, the gut microbiota induced by HGcc-1 supplement group and the control group were transferred to germ free Danio rerio, and then the levels of endotoxin binding protein (LBP), ALT and AST and the expression levels of C3 and C4 genes of germ free D. rerio were measured; finally, the levels of ALT and AST and the expression levels of C3 and C4 genes in germ free D. rerio were tested when HGcc-1 directly acted on germ free D. rerio. The results showed that HGcc-1 had no effect on the weight gain rate of C. carpio, but adding HGcc-1 significantly reduced the level of serum endotoxin, ALT and AST. The serum total complement level of the HGcc-1 supplement group was significantly increased, compared with control group. The 16S rRNA sequencing results showed that at the phylum level, the HGcc-1 supplement diet group increased the abundance of Fusobacterium by 47.1% compared to control group; the abundance of Proteobacteria was decreased by 70.7% compared with the control group; at the genus level, the HGcc-1 supplement diet group increased the abundance of Cetobacterium by 47.1% compared with the control group; the abundances of Citrobacter and Aeromonas were reduced by 56.6% and 70.9% respectively, compared with the control group. And it was further observed that the intestinal microbiota of HGcc-1 addition group decreased the content of endotoxin binding protein (LBP) and level of AST of the germ free (GF) D. rerio, and significantly increased the gene expression of complement component 3 and the complement component 4 (C3 and C4) of the GF D. rerio. At the same time, the direct interaction between HGcc-1 and GF D. rerio also decreased the ALT and AST levels of the GF D. rerio. This study shows that dietary B. subtilis HGcc-1 can improve the gut and liver health, serum complement and intestinal microbiota homeostasis of C. carpio fingerlings. This study laid a theoretical foundation for the further application of B. subtilis HGcc-1.
Effects of three kinds of lactic acid bacteria on growth, antioxidant and immune functions of Channa argus
KONG Yuxin, TIAN Jiaxin, PENG Sibo, WANG Guiqin
2021, 45(10): 1764-1774.   doi: 10.11964/jfc.20200912403
[Abstract](128) [FullText HTML](49) [PDF 5793KB](6)
In order to study the effects of lactic acid bacteria (LAB) on the growth, antioxidative status and immunity of Channa argus, 360 C. argus with an initial weight of (3.43 ± 0.05) g were selected and randomly divided into 4 groups. Each group was set up with 3 replicates, each with 30 C. argus. They were fed with basic feed and test feed supplemented with 108 CFU Lactococcus lactis L21 (L21 group), Lactobacillus plantarum W21 (W21 group), and Enterococcus faecalis L2 (L2 group). After 8 weeks, we collected the serum, liver, spleen, kidney and intestinal tissues to determine related indicators and genes expression. The results showed that compared with the control group, the three LAB added to the feed could significantly increase the average weight gain rate (AWGR), specific growth rate (SGR) and feed efficiency rate (FER) of C. argus, and the L21 group was significantly higher than other groups. Compared with the control group, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and alkaline phosphatase (AKP) in the L2 group were significantly higher than control group, the lysozyme (LZM) activity of the W21 and L2 groups was significantly higher than that of the control and L21 groups, and the immunoglobulin M (IgM) activity of each group was not significant. The genes expression levels of IL-1β, IL-8, IL-10 and TNF-α in various tissues all increased to varying degrees, and LAB could significantly promote the expression of immune-related genes in the intestine. Research shows that under the experimental conditions, L. lactis L21 had the best application effect in C. argus, and it could improve the growth, and immune function of C. argus.
Effects of aflatoxin B1 on growth performance and liver function of juvenile Pelteobagrus fulvidraco
ZHONG Lei, WANG Ziqin, WANG Jinlong, XIA Liqiu, CHEN Liyuan, ZHOU Jiancheng, HU Yi
2021, 45(10): 1775-1786.   doi: 10.11964/jfc.20201212564
[Abstract](182) [FullText HTML](91) [PDF 2961KB](5)
An experiment was conducted to study the effect of aflatoxin B1 on growth performance, digestive enzyme activities in intestinal tract and liver function of juvenile Pelteobagrus fulvidraco. Four experimental diets were prepared to contain 0 (control), 50, 100, 200 μg/kg aflatoxin B1. Each diet was randomly assigned to triplicate cages of 50 fish with an initial average weight of (6.00±0.10) g for 8 weeks. The results showed that: ① There were no significant differences in survival rate, feed coefficient ratio and specific growth rates of juvenile Pelteobagrus fulvidraco among all groups. The activity of trypsin in the AFB1 group significantly increased compared with the control group. When the AFB1 concentration reached 100 and 200 μg/kg, the amylase and lipase activities significantly decreased; ② With increasing AFB1 concentration, the levels of aspartate aminotransferase(AST), alanine aminotransferase(ALT), glucose, triglyceride, total bile acid and total cholesterol contents in serum significantly increased, and the AST, ALT activities in the liver significantly decreased; ③With increasing AFB1 concentration, the catalase activity and malondiadehyde content in the liver significantly increased. The superoxide dismutase activity significantly increased when the AFB1 concentration reached 100 and 200 μg/kg; ④ With increasing AFB1 concentration, the expression levels of sod and il-1β in the liver were significantly up-regulated, the expression levels of cat, il-10 and il-8 in the liver were significantly up-regulated when the AFB1 concentration reached 200 μg/kg; ⑤ Histological observations showed that an increase in the concentration of AFB1 caused some liver cells to present slight atrophy, hepatocyte nucleus shifted, cell boundary blurred, liver cell vacuolation degre. The results showed that under the experimental conditions, there was no significant effect on the growth of juvenile Pelteobagrus fulvidraco with the concentration of AFB1≤200 μg/kg, but it could affect the digestion and absorption function of the intestines, cause oxidative stress and inflammatory reactions in the liver, and result in liver function damage with the concentration of AFB1≥50 μg/kg.
Research progress on aquaculture and feeding regulation mechanism of Mandarin fish
LI Songlin, HAN Zhihao, WANG Xiaoyuan, CHEN Naisong
2021, 45(10): 1787-1795.   doi: 10.11964/jfc.20200812371
[Abstract](713) [FullText HTML](384) [PDF 2579KB](83)
Mandarin fish (Siniperca sp.) is a valuable freshwater economic fish in China, and its production has approached 330000 tons in 2019. This paper introduced aquaculture situation of Siniperca sp. from three aspects, including aquaculture status, aquaculture mode and selective breeding. The feeding habit of Siniperca sp. is unique, which relies on prey fish for lifetime. For many years, prey fish are mainly used to feed Siniperca sp., and the way of raising fish by fish not only causes the waste of fishery resources, but also aggravates the damage to environment and resources. Thus, the paper also summarized the external factors affecting feeding characteristics of Siniperca sp. species from environmental factors and feed properties, and analyzed the internal factors from the aspects of feeding sense organs and feeding regulation factors. This may be helpful to adjust the feeding habits of Siniperca sp. through artificial intervention, and provide necessary basis for its conversion to eat formula feed. Additionally, it is necessary to strengthen the research on the feeding regulation mechanism and nutritional physiological demand characteristics, so as to achieve the breakthrough of compound feed and promote the green and healthy development of its aquaculture industry.

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