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Herpesviral hematopoietic necrosis disease caused by cyprinid herpesvirus 2 (CyHV-2) results in huge economic losses for the gibel carp (Carassius auratus gibelio) aquaculture industry. A vaccination strategy is a feasible method to prevent CyHV-2 infection and the resulting economic losses. In this study, inactivators (including β-propiolactone, formaldehyde and binary ethylenimine) were used to prepare an inactivated vaccine. The optimal inactivated CyHV-2 vaccine (0.2% β-propiolactone inactivates CyHV-2 for 48 h) mixed with β-glucan, anisodamine, chitosan, and astragalus polysaccharide (APS) adjuvants were injected into gibel carp. The β-glucan and APS combined with inactivated vaccine significantly improved the relative immune protection rate of gibel carp against CyHV-2 infection. The highest specific antibody levels in β-glucan and APS groups were found in serum by ELISA assay and antibody neutralization titer. Furthermore, adjuvant addition groups produced better results for lysozyme, total superoxide dismutase, and complement C3 in serum. β-glucan and APS combined with vaccine treatment effectively enhanced mRNA expressions of important immune genes (IL-1β, IgM, IL-2 and IFN-γ2). Minimal tissue lesions (gill, spleen, and head kidney) and virus replication were seen in the β-glucan and APS groups by histopathological examination and expression analysis of CyHV-2 TK gene. These results indicated that the combination of inactivated vaccine and adjuvant β-glucan or APS is an effective method against CyHV-2 infection and provided a case study reference for prevention of fish viral diseases using inactivated vaccines.

The experiment was carried out to evaluate the effects of double-layer-coated Enterococcus faecium on the growth performance, liver biochemical indices, digestive enzyme activity, intestinal morphometry, immunity gene expression, and microbiota of crucian carps (Carassius auratus gibelio). A total of 320 fish (mean weight 11.0 ± 0.04 g) were randomly distributed into 3 treatment groups of 4 replicates per treatment (20 fish/replicate). Three different experimental diets were designed: dietary C without double-layer-coated E. faecalis, dietary LP supplemented with 1.0 × 107 CFU/g, and dietary HP supplemented with 1.0 × 108 CFU/g double-layer-coated E. faecalis. The fish was fed for 70 days with different diets, followed by a challenge with lipopolysaccharide (LPS). The results showed that the weight gain and specific growth rate increased and the feed conversion rate decreased in the dietary HP (P < 0.05). The dietary LP had higher lipase and protease activities, and amylase activity increased in the dietary LP and HP after the LPS challenge (P < 0.05). The dietary HP had higher villi height (VH), thicker muscular thickness (MT), and higher VH/MT (VCR) in the intestine (P < 0.05). The intestines were damaged by the LPS challenge; the damage to the dietary HP was alleviated, showing a higher VH, thicker MT, and higher VCR (P < 0.05). The glutathione peroxidase activity of the liver was increased in the dietary HP (P < 0.05). There was no significant difference in liver antioxidant capacity with the LPS challenge among all diets. There was no significant difference in the expression level of the Occludin and Claudin-12 genes among all diets that was up-regulated in dietary HP after LPS challenge (P < 0.05). High-throughput sequencing revealed that the supplementation of double-layer-coated E. faecium increased the species diversity of the intestinal. In conclusion, double-layer-coated E. faecium can improve the absorption of nutrients, enhance immunity, maintain balance in the intestine microbiota, and promote the growth of crucian carp. The supplementation of double-layer-coated E. faecium in the diet can alleviate the intestinal damage caused by LPS challenge.

Carassius auratus gibelio, commonly known as crucian carp, is the main species of freshwater aquaculture in China. Due to high-density aquaculture and environmental pollution, various diseases continue to emerge, especially the diseases caused by pathogenic bacteria have seriously restricted the development of freshwater aquaculture. Among these, Aeromonas hydrophila (AH) is the one of the most serious fish disease causing economic losses among fish farmers. An in-depth understanding of the crucian carp's immune system and its genes involved in the response to bacterial infection is necessary for disease control. In this study, the breeding period was divided into the control group (C group) and the Bacillus licheniformis (B. licheniformis) group (BL group). After 4 weeks of culture, the crucian carp was infected with AH and divided into the control group (Cg group) and the B. licheniformis group (BLg group). After the 72-h challenge, the Illumina-based paired-end sequencing approach to analyze the transcriptome profile of the crucian carp gut following AH infection. A total of 472.05 million valid reads were found from the four intestinal samples and 403.18 million reads were mapped successfully, of which 243.34 million were unique. About GO enrichment analysis, significant differentially expressed genes (DEGs) were more in biological process (406 DEGs), regulation of transcription, DNA-templated (345 DEGs), and signal transduction (304 DEGs). In the cell components, membrane (1913 DEGs) and integral component of membrane (1789 DEGs) had a higher number of significantly different genes. In the molecular function, metal ion binding (780 DEGs), ATP binding (535 DEGs), transferase activity (491 DEGs), and nucleotide binding (482 DEGs) have a large number of significantly different genes. Regarding the KEGG enrich analysis section, this study is arranged in ascending P-value order, andthe most significant signaling paths are lysosome, glucose metabolism, cycline cycline receiver interaction, and phagosome. Among them, the cycline cycline receiver interaction has the highest difference in significant genes. In addition, 5 immune-related genes were selected for real-time fluorescence quantitative PCR analysis to verify the RNA-seq data, and the results showed that the expression of all 5 genes was upregulated, which was consistent with the results of our RNA-seq analysis. After analysis, it was found that B. licheniformis can alleviate the inflammatory response and protect the fish body. Our results provide a reference for further analysis of the antagonism and mitigation mechanism of B. licheniformis against AH. [ABSTRACT FROM AUTHOR]

An 88-day feeding trial was conducted to evaluate the effects of dietary inosine 5′-monophosphate (5′-IMP) on the growth performance and salinity and oxidative stress resistance in the juvenile gibel carp CAS III (Carassius auratus gibelio; initial body weight: 7.48 g). Four isonitrogenous and isoenergetic diets containing exogenous 5′-IMP were formulated. P1, P2, P3 and P4 were diets containing 5′-IMP at four concentrations (0, 1, 2 and 4 g kg−1). The four diets were randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, six fish per tank were netted randomly and placed into 12‰ saline water to test their response to salinity stress. The results indicated that the feed conversion rate was enhanced by dietary supplementation with 5′-IMP. The appetite, plasma neuropeptide Y level and feeding rate of the P3 group were lower than those in the control treatment group. Dietary supplementation with 5′-IMP improved the osmoregulatory adaptation of gibel carp under acute salinity stress. Six hours after the salinity stress treatment, in the dietary 5′-IMP treatment group, the plasma cortisol and K+ concentrations were lower and the Na+/K+-ATPase activity was greater than that in the control group. Dietary supplementation with 5′-IMP promoted the expression of the glucocorticoid receptors NKA-α1b and NKCC and retarded the expression of Hsp70 in P4-treated gill filaments and kidneys. Dietary supplementation with 5′-IMP resulted in a stable oxidative-stress-resistant phenotype characterized by increased levels of cellular antioxidants, including SOD, catalase, glutathione peroxidase, glutathione reductase and MPO. The above results of the current study demonstrate that supplementation of 5′-IMP can promote feed utilization and have positive influences on the salinity and oxidative stress resistance of gibel carp. [ABSTRACT FROM AUTHOR]

The experiment was designed to evaluate the effects of different levels of antimicrobial pep‐ tides on the growth, immunity and antioxidant performance of the Juvenile Carassius auratus gibelio.In the experiment, five groups of isonitrogenous and isolipidic diets were designed. A diet without antimicrobial peptides as control group (CK group), and the diets with 50, 75, 100, 125 mg/kg antimicrobial pep‐ tides as experimental diets (D1 group, D2 group, D3 group, D4 group) were fed to Carassius auratus gibelio in the breeding tank [initial average body mass (9.40±0.20) g], three repeats for each group, each group had 25 tail of test fish. After 8 weeks of culture, the fish body composition, growth and digestion performance, immune and antioxidation performance, as well as the serum related indexes were tested. The results showed that: compared with CK group, the growth performance and feed utilization rate of the fish were not influenced by the different levels of the antimicrobial peptides (P>0.05); the muscle crude lipid content the fish were decreased with the increased addition level of the antimicrobial peptides, the crude lipid content of the muscle and liver of D4 group were significantly lower than that of CK group (P<0.05); compared with CK group, the activities of trypsin in the anterior intestine of D2 group increased significantly (P<0.05); the superoxide dismutase activities and total antioxidant capacity of the liver in D2 and D3 groups were significantly increased (P<0.05); the activities of serum lysozyme in D2 and D3 groups increased significantly (P<0.05). The above results indicated that adding Fulitai antibacterial peptide to the diets of Juvenile Carassius auratus gibelio could reduce the muscle lipid content and improve the immune and antioxidant performance of the fish, and the effect would be better when the addition amount of antibacterial peptide were at 75 mg/kg or 100 mg/kg. [ABSTRACT FROM AUTHOR]

The experiment was to investigate the effect of adding bile acid to high-lipid diet on growth performance, muscle nutrition and fatty acid composition of gibel carp. A total of 450 healthy and initial body weight (32.37±0.13) g juvenile fish were randomly divided into five groups, with three replicates in each group and 30 fish in each replicate. Five kinds of iso-nitrogen and iso-lipid feed were prepared by adding 0 (BA0), 200 (BA200), 400 (BA400), 600 (BA600) and 800 mg/kg (BA800) bile acids to basic feed containing 12% soybean oil, respectively. The experiment lasted for 8 w. The results showed that compared with BA0, FBW of BA400 and BA600 gibel carp was significantly increased (P<0.05), WGR of BA600 was significantly increased (P<0.05), VSI was significantly decreased (P<0.05). The FCR of gibel carp in BA200, BA400 and BA600 was significantly decreased (P<0.05). HSI of all experimental groups was significantly decreased (P<0.05). CF of BA800 was significantly increased (P<0.05). Compared with BA0, muscle crude fat content of experimental groups was significantly decreased (P<0.05), and MUFA content was significantly increased (P<0.05). The crude protein content of gibel carp in BA400 and BA600 were significantly increased (P<0.05). The crude ash content of gibel carp in BA600 and BA800 were significantly decreased (P<0.05). The study indicates that adding 400~600 mg/kg bile acid to high-lipid diet can promote growth of gibel carp, increase the utilization rate of feed, promote fat digestion, absorption and decomposition for energy supply, improve muscle fatty acid composition. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An 88-day feeding trial was conducted to evaluate the effects of dietary inosine 5′-monophosphate (5′-IMP) on the growth performance and salinity and oxidative stress resistance in the juvenile gibel carp CAS III (Carassius auratus gibelio; initial body weight: 7.48 g). Four isonitrogenous and isoenergetic diets containing exogenous 5′-IMP were formulated. P1, P2, P3 and P4 were diets containing 5′-IMP at four concentrations (0, 1, 2 and 4 g kg−1). The four diets were randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, six fish per tank were netted randomly and placed into 12‰ saline water to test their response to salinity stress. The results indicated that the feed conversion rate was enhanced by dietary supplementation with 5′-IMP. The appetite, plasma neuropeptide Y level and feeding rate of the P3 group were lower than those in the control treatment group. Dietary supplementation with 5′-IMP improved the osmoregulatory adaptation of gibel carp under acute salinity stress. Six hours after the salinity stress treatment, in the dietary 5′-IMP treatment group, the plasma cortisol and K+ concentrations were lower and the Na+/K+-ATPase activity was greater than that in the control group. Dietary supplementation with 5′-IMP promoted the expression of the glucocorticoid receptors NKA-α1b and NKCC and retarded the expression of Hsp70 in P4-treated gill filaments and kidneys. Dietary supplementation with 5′-IMP resulted in a stable oxidative-stress-resistant phenotype characterized by increased levels of cellular antioxidants, including SOD, catalase, glutathione peroxidase, glutathione reductase and MPO. The above results of the current study demonstrate that supplementation of 5′-IMP can promote feed utilization and have positive influences on the salinity and oxidative stress resistance of gibel carp.

The experiment was to investigate the effect of nutrient peptide on growth performance, serum biochemistry and antioxidant properties of Carassius auratus gibelio. Carassius auratus gibelio with an average body weight of 50 g/tail were randomly divided into two groups, Carassius auratus gibelio in control group were fed with basal diet, Carassius auratus gibelio in experimental group were fed with basal diet supplemented with 2.0% nutrient small peptide, with a feeding volume of 400 Carassius auratus gibelio/667 m2. The pond area of the experimental group and control group was 52 360 and 51 362 m2, respectively. The experiment lasted for 128 d. The results showed that the body weight and body length of Carassius auratus gibelio in experimental group were extremely higher than those of control group (P<0.01). serum total protein and albumin content was extremely higher than that of control group (P<0.01), and glucose content was extremely lower than that of control group (P<0.01), serum superoxide dismutase activity, total antioxidant capacity and malondialdehyde content were higher than that of control group. The experiment indicates that adding 2% nutritional peptide to diet can improve growth performance and health level of Carassius auratus gibelio. [ABSTRACT FROM AUTHOR]

Aflatoxin contamination of food and water is a serious problem worldwide. This study investigated the defensive ability of gibel carp exposed to aflatoxin B1 (AFB1) by challenging it with cyprinid herpesvirus 2 (CyHV-2) infection. The data showed that AFB1 exposure significantly increased the mortality of CyHV-2-infected gibel carp, and enhanced the viral load in the fish liver, kidney, and spleen. The oxidative-antioxidant balance suggested that AFB1 induced severe oxidative stress, including increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the AFB1 exposed group, and the reduced activity of superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT) in the AFB1 exposed group. Meanwhile, the related expression of nuclear factor erythroid 2-related factor 2 (Nrf2), interferon regulatory factor 3 (IRF3) and the type 1 interferon (IFN1) were noticeably down-regulated, but caspase-1 was up-regulated, after exposure to AFB1, demonstrating that fish are unable to avoid the virus infection. It should be noted that the intestinal microbiota diversity and richness were lower in the AFB1 exposed group, and the composition of intestinal microbiota was affected by AFB1, resulting in the higher abundance of bacteria (such as Aeromonas and Bacteroides) and the lower abundance of potentially beneficial bacteria (such as Cetobacterium and Clostridium) in the AFB1 exposed group. This research provides insight into the possibility that AFB1 may increase the susceptibility of C. gibelio to CyHV-2 infection, and thus amplify the viral outbreak to endanger ecological safety in aquatic environment. [ABSTRACT FROM AUTHOR]

In the high-density pond aquaculture of gibel carp (Carassius auratus gibelio) in China, copper sulfate (CuSO 4) and trichlorfon (Tri) are commonly used, either in combination or alternately, to prevent and control various diseases and harmful algae. Despite their widespread use, there is a lack of studies on the toxic effects of CuSO 4 and Tri on gibel carp, particularly regarding their combined application. This study assessed the effects of exposure to CuSO 4 (0.5 mg/L) and Tri (0.5 mg/L), both individually and in combination, on gibel carp over 21 days. Histopathological assessments revealed significant structural damage to the liver and intestines in gibel carp exposed to either CuSO 4 or Tri alone, with co-exposure notably intensifying these effects. Analysis of antioxidant enzyme activities revealed a substantial reduction in the liver and intestines, concurrent with a significant rise in the oxidative stress marker malondialdehyde in both single and combined exposure groups. Moreover, quantitative PCR analyses indicated a downregulation of immune-related genes post-exposure, with the combined treatment causing more severe suppression. This suppressed immune response correlated with a reduced ability to resist infection by the pathogenic bacterium Aeromonas hydrophila , particularly in the combined exposure group. This indicates that long-term exposure to CuSO 4 and Tri, particularly in combination, induces significant oxidative stress damage in the liver and intestinal tissues, suppresses immune function, and reduces disease resistance. Additionally, 16S rRNA sequencing of the intestinal microbiota revealed that CuSO 4 and Tri exposure altered the diversity and composition of intestinal microbial communities, potentially bringing both benefits and drawbacks. These findings underscore the need for careful management of CuSO 4 and Tri in aquaculture to mitigate their adverse impacts, especially when used in combination for an extended period. • CuSO 4 and trichlorfon caused significant liver and intestine damage. • CuSO 4 and trichlorfon exposure, individually or combined, induces oxidative stress. • Immune-related gene expressions were inhibited after exposure to CuSO 4 and trichlorfon. • Combined CuSO 4 and trichlorfon exposure increased mortality rates post A. veronii infection. • CuSO 4 and trichlorfon significantly reduced intestinal microbial diversity and richness. [ABSTRACT FROM AUTHOR]

Freshwater fish are frequently disliked by consumers due to their fishy odor and loose texture. Therefore, salinity treatment before market release is crucial for improving the muscle quality of freshwater fish. In this study, Carassius auratus gibelio was temporarily reared in low-salinity seawater (6 ppt) for 15 days, and changes of antioxidant levels, muscle texture, and intestinal microbial were determined. After temporary rearing in seawater, the hardness, gumminess, and chewiness of the muscle texture improved, and the relative contents of fishy and fatty odors decreased. This indicated that low-salinity treatment can enhance muscle quality and flavor while reducing fishy odor. According to microbiome research, low-salinity saltwater temporarily reduced the relative abundance of some opportunistic pathogens, such as Vibrio (from 47.61% to 0.1%) and Shewanella (from 15.20% to 5.86%) in the intestinal tract of crucian carp, and increased the relative abundance of beneficial bacteria, such as Sphingomonas (from 2.52% to 28.38%). This study can provide a reference for using low-salinity seawater for temporary rearing to enhance the quality of fish prior to marketing. [Display omitted] • Low-salinity seawater transient improves carp meat quality. • Low-salinity seawater reduces fishy smell and enhances taste of carp. • Low-salinity seawater alters intestinal microbial community. • Low-salinity seawater may inhibit pathogenic bacteria in intestines. [ABSTRACT FROM AUTHOR]

Malathion is an organophosphorous insecticide, used in agriculture and a possible source of environmental poisoning. During malathion metabolization, mitochondria generates reactive oxygen species, responsible for significant structural changes. In this study, gills and kidney histological changes in Carassius auratus gibelio exposed to 0.05 mg/l malathion were investigated. In kidney, the effects were dramatic. The 24 -72 hours exposure to malathion induced cytoplasm vacuolization and changes in cell and nuclear volumes. In addition, necrotic renal tubules appeared, nuclear malformations of epithelial cells, anisokary, nuclei pycnosis and nuclei hypertrophy, were noticed. Epithelial ruptures, secondary lamellae fusion and hyperplasia of branchial epithelium, vascular congestion were the main changes noticed soon after pollutant exposure. We suggest that structural changes in gill and kidney could be used as good response to aquatic pollution with organophosphorous insecticides.

This study evaluated the effects of poly-γ-glutamic acid (γ-PGA) diets on the growth, antioxidant capacity, and nutrient absorption of gibel carp. Six groups (Control, PGA-25, PGA-50, PGA-100, PGA-200 and PGA −400) were supplemented with different γ-PGA addition (0, 25, 50, 100, 200, 400 mg/kg), respectively, and were fed for 8 weeks. The results showed that the final weight (FW), weight gain (WG) were quadratically and cubically increased (P 0.05), whereas the crude fat was cubically affected by graded dietary γ-PGA levels (P = 0.049). The serum albumin (ALB) content was cubically increased, whereas the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, triglyceride (TG) and total cholesterol (TC) were decreased with increasing dietary γ-PGA levels. The alkaline phosphatase (ALP) activity, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), however, were not affected by the γ-PGA trail. Digestive enzymes, including amylase, lipase and trypsin in the intestine and liver, were all quadratically or cubically increased with increasing dietary γ-PGA levels (P

To investigate the physiological features of the melanocortin-4 receptor (MC4R) gene, which was demonstrated to be strictly related to food regulation in vertebrates, the coding DNA sequence (CDS) of MC4R in gibel carp (Carassius auratus gibelio) was cloned and characterized (designated as CgMC4R). In this study, the CDS of the CgMC4R gene was 981 bp long that predicted to encode a protein of 327 putative amino acids with seven potential hydrophobic transmembrane domains (TMD1-TMD7). Bioinformatic analysis revealed that CgMC4R shared 99% identity with that in goldfish and exhibited high similarity with that in Cyprinidae species. In addition, CgMC4R was predominantly expressed in the hypothalamus. Furthermore, hypothalamic CgMC4R mRNA expression exhibited altered responses under fed/fasting conditions. In the postprandial experiment, the expression of CgMC4R in the unfed group was upregulated at 1 and 3 h postfeeding compared to that in the fed fish, respectively. During long-term fasting, CgMC4R mRNA transcript levels dramatically increased within 1, 3, 5, and 7 days of fasting. After refeeding, the CgMC4R gene presented a marked decrease in expression after refeeding at 9 days and finally returned to the level in control group. Taken together, these results indicated that the MC4R gene plays a significant role in the feed intake of gibel carp and provides basic evidence to explore the appetite-related roles of MC4R in gibel carp. [ABSTRACT FROM AUTHOR]

Poly‐β‐hydroxybutyrate (PHB) can promote growth and enhance immunity of aquatic animals such as gibel carp, Carassius auratus gibelio. However, the optimal dietary supplementation level and feeding duration for gibel carp are still unclear. In this study, effects of various PHB supplementation levels on gibel carp growth performance, digestive enzyme activities, immune function, disease resistance, and intestinal mucosal barrier were evaluated. Six experimental diets differing in PHB levels were formulated, that is, 0% (P0 as control), 0.5% (P0.5), 1% (P1), 2% (P2), 4% (P4), and 8% (P8). Results indicated that PHB promoted fish growth performance significantly (p < 0.05). Compared to control group P0, the intestinal lipase, protease, and amylase activities in group P4 were significantly increased after 30 days (p < 0.05). Meanwhile, dietary PHB supplementation at 4% level for 30 days and 0.5% for 60 days upregulated the mRNA expression of immune‐related genes, including IL‐11, ITLN, MPO, KRT‐8, DUSP‐1, and PNP‐5α (p < 0.01). Furthermore, PHB at 4% for 30 days showed positive effects on disease resistance against both viral and bacterial infections and exerted beneficial effects on maintaining epithelial mucosal barrier integrity. In conclusion, 4% PHB supplementation for 30 days or 0.5% for 60 days was recommended for gibel carp culture. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian Ocean University is the property of Journal of Dalian Ocean University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, contamination of potentially toxic elements (Cr, Mn, Cu, Zn, Hg and Pb) and species dominant in the fish community of Lake Kenon – Carassius auratus gibelio (Bloch 1782) and Perca fluviatilis (Linnaeus 1758) – were investigated. Chemical elements in samples were determined by atomic emission spectrometry (iCAP-6500, Thermo Scientific, USA) and mass spectrometry (X-7, Thermo Elemental, USA). It was reported that water in Lake Kenon contained low concentrations of the studied metals. The bottom sediments are enriched with Mn, Zn, Hg and Pb. Bioaccumulation factors of chemical elements accumulated from the surrounding water for P. fluviatus and C. auratus gibelio in descending order are as follows: Zn > Pb > Hg > Cu. P. fluviatus accumulates Hg in equal measure from both water and bottom sediments. Manganese and mercury are accumulated in the muscles of C. auratus gibelio from bottom sediments. The high accumulation ratio of Zn and Hg in C. auratus gibelio was obtained from Chara sp. (24 times) and Chironomus spp. (38 times), respectively. High accumulation ratio of Zn (26 times) and Hg (29 times) in P. fluviatus was obtained from amphipods. At the same time, Hg in P. fluviatus muscles was accumulated at high level from Chironomus spp. (67 times). In this way, management decisions for mitigation practices in Lake Kenon should be focussed on for the disposal of wastewater from the ash dump contaminated with chemical elements.

Paeonol, a naturally occurring polyphenol isolated from medical plant, has been known to exhibit anti-oxidative and anti-inflammatory effects. In order to evaluate the effect of paeonol on Carassius auratus gibelio infected by pathogenic bacteria Aeromonas hydriphila. 750 fish were randomly divided into 5 groups, which separately treated with 0.85% sterile saline (blank), A. hydriphila (negative control), A. hydriphila with paeonol (4 mg/kg, 64 mg/kg), and A. hydriphila with enrofloxacin (12 mg/kg, positive control). Fish were anaesthetized with MS-222 (100 mg/L), and samples were collected at 6 and 72 h after A. hydriphila challenge. The results showed that compared with the negative group, the survival in paeonol groups marked increased by 14.75% and 18.94%. The plasma immunoglobulin M (IgM) was notably increased, and low density lipoprotein (LDL) was significantly decreased in paeonol groups at 6 h (P < 0.05). The antioxidative enzymes catalase (CAT), total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) were significantly increased in paeonol groups at 6 h, while malondialdehyde (MDA) and myeloperoxidase (MPO) contents were lower (P < 0.05). The inflammatory related genes MyD88 and TLR-5 were significantly downregulated, and the TLR-3 was significantly increased in paeonol groups at 72 h (P < 0.05). In addition, histopathological analyses showed that the lesion in liver, spleen and caudal kidney were considerably attenuated in paeonol groups. In conclusion, paeonol could increase the survival rate, mitigate oxidative damage, inflammation, tissue lesions, and improve the immunity of gibel carp challenged with A. hydrophila. [Display omitted] • Paeonol enhanced antioxidant and anti-inflammatory ability challenged with A. hydrophila. • Paeonol attenuated liver, spleen and caudal kidney lesions challenged with A. hydrophila. • Paeonol increased the survival of Carassius auratus gibelio challenged with A. hydrophila. [ABSTRACT FROM AUTHOR]

The experiment was to explore the effect of different fat sources in diet on growth of Ctenopharyngodon idella, Mylopharyngodon piceus and Carassius auratus gibelio, as well as conventional muscle nutrients and fatty acid composition. A total of 240 fish with an initial body weight of (34.8±0.4) g Ctenopharyngodon idella, (35.0±0.4) g Mylopharyngodon piceus, (26.3±0.1) g Carassius auratus gibelio were randomly divided into four groups with three replicates in each group and 60 fish in each replicate (three species mixed culture, 20 fish per species). The basic diet (BD group) without oil and fat was used as control group, and 6% soybean oil (SO group), fish oil (FO group) and lard (LO group) were added to basic diet as test groups. The experiment lasted for 8 w. The results showed that the average survival rate of the three species of fish in each group was significantly higher than that in BD group (P<0.05), and the survival rate of Mylopharyngodon piceus in test group was significantly higher than that in BD group (P<0.05). The total final weight and average weight gain of the three fish in each group were significantly higher than that in BD group (P<0.05). The feed coefficient of each group was significantly lower than that in BD group (P<0.05). The visceral body ratio and liver body ratio of Ctenopharyngodon idella in FO group were significantly higher than those in BD group (P<0.05), and the visceral body ratio and liver body ratio of Mylopharyngodon piceus in LO group were significantly higher than those in BD group (P<0.05). The visceral body ratio of Carassius auratus gibelio in BD group was significantly lower than that in other groups (P<0.05), and the liver to body ratio of Carassius auratus gibelio in FO group was significantly lower than that in other groups (P<0.05). The crude protein content of Ctenopharyngodon idella in FO group was significantly higher than that in BD group and SO group (P<0.05), and the crude protein content of Mylopharyngodon piceus in SO group was significantly lower than that in other groups (P<0.05). The crude fat content of Ctenopharyngodon idella in LO group was significantly higher than that in other groups (P<0.05), and the crude fat content of Mylopharyngodon piceus in SO group was significantly higher than that in other groups (P<0.05). The content of C16:0 was the highest in the three fish muscle fatty acids, followed by C18:1n-9, C18:0 and C18:2n-6. The content of C18: 2n-6, C18:3n-3 in SO group were significantly higher than other groups (P<0.05). The content of C20: 5n-3, C22:6n-3 in FO group were significantly higher than other groups (P<0.05). The content of C16:0, C18:1n-9 in LO group were significantly higher than those in other groups (P<0.05). The study indicates that adding fish oil to Ctenopharyngodon idella bait has a good growth-promoting effect, but adding 6% soybean oil and lard has no obvious growth-promoting effect, which indicates that Ctenopharyngodon idella has lower requirements for feed fat level. Adding 6% soybean oil, fish oil and lard to Mylopharyngodon piceus bait has better growth-promoting effect. Adding 6% fish oil and lard to Carassius auratus gibelio has better growth-promoting effect, but soybean oil has poor effect. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the Effect of different levels of turmeric on diet on Blood indicators and histopathological examination of liver, kidney and intestine in Juvenile Sevryuga. In this regard, 120 specimens were distributed in 12 Treatments (45 ± 0.5g) and (26 ± 0.5cm). The fish were fed in 4 groups with 4 experimental diets containing different levels of turmeric including: 0, 0.5, 1 and 2% formulated. At the end of the course , blood indices and histopathological examination of liver, kidney and intestine were evaluated. Increasing the dose of turmeric in 2% of the diet increased the amount of hematocrit, hemoglobin, RBC, AST and ALT and the difference between treatments was significant (P 0.05). The results of MCV ٬ MCH and MCHC analysis showed that the amount of the mentioned indicators decreased with increasing the dose of turmeric and the difference between the treatments was significant (P

Abstract In aquaculture, antibiotics are commonly used to provide protection against pathogens; however, this practice has become controversial due to increased occurrences of microbial resistance, and alternatives are needed. This study aimed to investigate the antimicrobial activity of yeast glycoprotein (YG) against Aeromonas caviae. Pathogens were isolated from liver of diseased Carassius auratus gibelio. Based on morphological and biochemical analysis, together with 16S rRNA gene sequencing, the isolated strains were identified as A. caviae and concluded as clones of a single strain and named L2. Further pathogenicity analysis revealed that A. caviae possessed β‐haemolysis, and its median lethal dose for C. gibelio was 1.33 × 106 CFU/ml. Hepatic adenylate kinase and pyruvate kinase activities of C. gibelio were inhibited post–A. caviae infection. Antimicrobial drug test suggested that A. caviae was a multidrug‐resistant organism but could be inhibited by YG in vitro. Minimum inhibitory and bactericidal concentration of YG was 83.3 mg/ml and 166.7 mg/ml, respectively. Microbiota sequencing results showed that YG supplement could obviously decrease the relative abundance of Aeromonas and increase the microbial diversity. Our study revealed that A. caviae from C. gibelio was a multidrug‐resistant bacteria strain, and could be significantly inhibited by YG in vivo and in vitro, thus providing important insights into ecological control and pathogenesis of A. caviae in aquaculture.

Aflatoxin contamination of food and water is a serious problem worldwide. This study investigated the defensive ability of gibel carp exposed to aflatoxin B1 (AFB1) by challenging it with cyprinid herpesvirus 2 (CyHV-2) infection. The data showed that AFB1 exposure significantly increased the mortality of CyHV-2-infected gibel carp, and enhanced the viral load in the fish liver, kidney, and spleen. The oxidative-antioxidant balance suggested that AFB1 induced severe oxidative stress, including increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the AFB1 exposed group, and the reduced activity of superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT) in the AFB1 exposed group. Meanwhile, the related expression of nuclear factor erythroid 2-related factor 2 (Nrf2), interferon regulatory factor 3 (IRF3) and the type 1 interferon (IFN1) were noticeably down-regulated, but caspase-1 was up-regulated, after exposure to AFB1, demonstrating that fish are unable to avoid the virus infection. It should be noted that the intestinal microbiota diversity and richness were lower in the AFB1 exposed group, and the composition of intestinal microbiota was affected by AFB1, resulting in the higher abundance of bacteria (such as Aeromonas and Bacteroides) and the lower abundance of potentially beneficial bacteria (such as Cetobacterium and Clostridium) in the AFB1 exposed group. This research provides insight into the possibility that AFB1 may increase the susceptibility of C. gibelio to CyHV-2 infection, and thus amplify the viral outbreak to endanger ecological safety in aquatic environment.

Cadmium (Cd) is a highly toxic, nonessential heavy metal that has been associated with a variety of toxicological effects in both humans and animals. The main objective of this research was to investigate bioaccumulation, intestinal apoptosis, and digestive dysfunction effects of waterborne cadmium in the intestine of crucian carp Carassius auratus gibelio. Fish were exposed to 0, 100, and 500 μg/L waterborne Cd for 4 weeks, and the results showed that Cd accumulation in the intestine was significantly increased as Cd concentration increased. The intestinal structure was severely damaged, including mucosal fold length decreased, the rough endoplasmic reticulum underwent marked swelling and indistinct, and the intestinal microvilli transformed or nearly disappeared. The activities of intestinal apoptosis enzymes (Caspases 3, Caspases 8, and Caspases 9) and apoptosis rate of enterocyte cells were significantly elevated in 500 μg/L waterborne Cd group, activities of digestive enzymes (amylase and protease) were significantly decreased by 500 μg/L waterborne Cd. Overall, our results demonstrated that waterborne Cd exposure could increase Cd bioaccumulation in the intestine and destroy the intestinal digestibility of crucian carp, which in turn led to the occurrence of cell apoptosis.

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Myxozoans are common microparasites in wild and farmed fish, and some species cause severe disease in cultured gibel carp. During the investigation of actinospores in oligochaetes from the gibel carp ponds form April 2018 to July 2019, nine actinospore types were found in the oligochaete Branchiura sowerbyi Beddard. Based on morphological characteristics, they were identified into six collection groups, including one Raabeia-type, two Aurantiactinomyxon- types, two Neoactinomyxum-types, two Triactinomyxon-types, two Echinactinomyxon-types and one Hungactinomyxon- type. The present study described six of them, Triactinomyxon type HZ, Triactinomyxon type DF, Echinactinomyxon type LY1, Echinactinomyxon type LY2, Neoactinomyxum type LY1 and Hungactinomyxon type DF. Blastn search using SSU rDNA gene sequences indicated that Triactinomyxon type HZ and Triactinomyxon type DF have the highest 93.39% and 94.48% homology similarity with Triactinomyxon type CZ, respectively. Echinactinomyxon type LY1 and Myxobolus lentisuturalis have the highest similarity (96.88%, AY119688); Echinactinomyxon type LY2 has the highest similarity with Hungactinomyxon type 1 (97.86%, AY779062); Neoactinomyxum type LY has the highest similarity with Thelohanellus sp. (92.48%, MK412938); Hungactinomyxon type DF has the highest similarity with Hungactinomyxon (99.41%--99.64%). Phylogenetic analyses showed that Triactinomyxon type HZ and Triactinomyxon type DF clustered in the Chloromyxum subclade; Echinactinomyxon type LY1 and Echinactinomyxon type LY2 clustered in the Myxobolus clade; the Neoactinomyxum type LY1 clustered in the Thelohanellus clade. [ABSTRACT FROM AUTHOR]

Carassius auratus gibelio is susceptible to the herpesviral hematopoietic necrosis (HVHN) disease caused by cyprinid herpesvirus 2 (CyHV-2) infection during the breeding process. Nevertheless, the report on biological response of CyHV-2 with C. auratus gibelio was limited, especially in vitro. In this study, host gene expression profiling was mostly analyzed in caudal fin cells of Carassius auratus gibelio (GiCF) underlying CyHV-2 infection. Transcriptomics and proteomics were employed to study the differential expression gene and revealed the host genes involved in pathway during the CyHV-2 infection. Transcriptome analysis revealed that compared with the control group, there were 11 335 and 19 421 differentially expressed unigenes at 48 h and at 96 h, respectively. Furthermore, proteome analysis showed that there were a total of 9008 proteins, among which 169 proteins were differential expression in the 48 h group and 502 proteins in the 96 h group. Notably, 10 and 158 differentially co-expressed genes at mRNA and protein levels (cDEGs) were reliably quantified at 48 h and 96 h, respectively. Interestingly, significantly different expressed genes both in the transcriptome and the proteome were identified, including GNG7, Hsp90a, THBS1 and RRM2. The result suggested that PI3k-AKT pathway was activated, but the p53 signaling pathway was suppressed. The above result will lay the foundation for understanding the mechanisms of host defense virus invasion during CyHV-2 infection. • 31 and 167 differentially co-expressed genes were identified at 48 h and at 96 h inCyHV-2infected GiCF cell, respectively. • 10 differentially co-expressed genes both at 48 h and 96 h were verified by Real-time PCR in CyHV-2 infected GiCF cell. • PI3K-AKT pathway and p53 signal pathway play their important roles in GiCF cell during CyHV-2 infection. [ABSTRACT FROM AUTHOR]

In aquaculture, antibiotics are commonly used to provide protection against pathogens; however, this practice has become controversial due to increased occurrences of microbial resistance, and alternatives are needed. This study aimed to investigate the antimicrobial activity of yeast glycoprotein (YG) against Aeromonas caviae. Pathogens were isolated from liver of diseased Carassius auratus gibelio. Based on morphological and biochemical analysis, together with 16S rRNA gene sequencing, the isolated strains were identified as A. caviae and concluded as clones of a single strain and named L2. Further pathogenicity analysis revealed that A. caviae possessed β‐haemolysis, and its median lethal dose for C. gibelio was 1.33 × 106 CFU/ml. Hepatic adenylate kinase and pyruvate kinase activities of C. gibelio were inhibited post–A. caviae infection. Antimicrobial drug test suggested that A. caviae was a multidrug‐resistant organism but could be inhibited by YG in vitro. Minimum inhibitory and bactericidal concentration of YG was 83.3 mg/ml and 166.7 mg/ml, respectively. Microbiota sequencing results showed that YG supplement could obviously decrease the relative abundance of Aeromonas and increase the microbial diversity. Our study revealed that A. caviae from C. gibelio was a multidrug‐resistant bacteria strain, and could be significantly inhibited by YG in vivo and in vitro, thus providing important insights into ecological control and pathogenesis of A. caviae in aquaculture. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As one of the most important fish in freshwater aquaculture, gibel carp (Carassius auratus gibelio) is easily susceptible to Cyprinid herpesvirus 2 (CyHV-2). Immersion vaccination has attracted many researchers due to its simple operation in preventing infectious diseases. However, the unavoidable disadvantage is that the immersion vaccine must be used with adjuvants to get a better performance. In this study, gibel carps were vaccinated by a 60 min bath in a β-propiolactone-inactivated Cyprinid herpesvirus 2, mixed with DTT, β-glucan, anisodamine and scopolamine, respectively. After immunization, the fishs were challenged by CyHV-2 in 2 weeks. By analyzing pathological section, we found that β-glucan, anisodamine and scopolamine groups protected the gibel carp compared to the control group, which was consistent with the trend of survival rate. Specifically, β-glucan group in serum appeared best on lysozyme, TSOD and complement C3. Real time quantitative RT-PCR results demonstrated that in both spleen and head kidney tissues, mRNA expressions of typical Th1 immune response cytokines IL-2 and IFN-γ2 in β-glucan group and anisodamine group were significantly higher than other groups and the level of immunoglobulins related to systemic immunity (IgM) and mucosal immunity (IgZ) were also enhanced in the immune period. DTT group slightly affected immune gene and serum enzyme activity, while did not show an adjuvant effect on survival rate. In addition, four adjuvant groups could obviously inhibit CyHV-2 replication. This study explored and proved the good efficiency of β-glucan or anisodamine as immersion immune adjuvant and also provided reference for improving the efficiency of immersion immunity. • The vaccine can enter the fish and stimulate the immune response through the hypertonic immersion immune pathway. • β-glucan and anisodamine as immersion immune adjuvant improves the survival rate of gibel carp against CyHV-2. • β-glucan as adjuvant reinforces inflammatory response, Th1 type immune response and the expression level of IgM and IgZ. • DTT, β-glucan, anisodamine and scopolamine strengthen the vaccine inhibiting CyHV-2 replication. [ABSTRACT FROM AUTHOR]

• Gibel carp IFNa and IFNc display significantly antiviral potential to viral infection. • ISRE motifs within promoters are responsible for the induction of carp IFN and IFNc by diverse stimuli including themselves. • Gibel carp IFNa and IFNc have different-sized 3′UTR that is a potential factor for regulation of IFN response. Fish interferon (IFN)-mediated antiviral innate immunity is the first line of defense against virus invasion. In the present study, we identify two fish IFN genes (here tentatively named IFNa and IFNc) with different-sized 3′ UTRs from clone F strain of gibel carp Carassius auratus gibelio. Carp IFNa has a relatively short 3′UTR without AU-rich elements (AREs) but IFNc has a long one with 9 AREs. Functionally, carp IFNa and IFNc display significantly antiviral potential to viral infection, likely through induction of downstream IFN-stimulated genes (ISGs). Both carp IFN genes are induced by viral infection, poly(I:C) treatment and IRF3/7, which are ascribed to the IFN-sensitive response elements (ISRE) within their promoters. Carp IFN genes are also induced by each other and by themselves, indicating existence of a positive feedback loop in fish IFN-mediated antiviral immune response. Comparative analyses of 3′UTR-mediated expression regulation at mRNA and protein levels show that the ARE-containing 3′UTR of carp IFNc rather than the short 3′UTR of carp IFNa promotes mRNA decay but instead results in high-level protein expression, indicating that 3′UTR of fish IFN mRNAs might be a potential factor for regulation of IFN-mediated antiviral immune response. Considering a fact that a given protein function is largely related to its protein level, these results suggest that both promoter and 3′UTR contribute to the transcription and translation of fish IFN genes, thus shaping their eventually antiviral potential. [ABSTRACT FROM AUTHOR]

• GA3 induced erythrocyte nucleus changes in gibel carp. • GA3 induced liver dysfunction and oxidative stress in gibel carp. • GA3 caused ER stress and apoptosis in the lives of gibel carp. Gibberellic acid (GA3), one of the most plant growth stimulator, is widely applied in agricultural regions and in beer industry. However, GA3 residue remained in soil and water can cause toxicity to all organisms. In this study, we investigated the mechanisms of GA3-induced hepatic injury in gibel carp (Carassius auratus gibelio). We found that GA3 exposure caused oxidative stress, endoplasmic reticulum stress (ERS), and apoptosis. The gibel carp exposed to GA3 exhibited significant alteration in erythrocyte nuclei. GA3 induced liver damage, as indicated by increasing the aminopherase activities. GA3 led to oxidative stress by increasing malondialdehyde content and decreasing the activities of CAT and GPx. GA3 stimulated ERS and increased the expression of grp78, perk, eif2s1α, chop, atf4, ire1α, xbp1, and atf6. Additionally, GA3 down-regulated the level of anti-apoptotic gene Bcl-2 and up-regulated the levels of pro-apoptotic genes bax and caspase-3. Overall results demonstrated that GA3 caused hepatic injury in gibel carp by increasing oxidative stress, ERS, and apoptosis. [ABSTRACT FROM AUTHOR]

Aeromonas species often cause disease in farmed fish. In the present study, dominant bacteria were isolated from diseased crucian carp (Carassius auratus gibelio). Based on this, a bacterial isolate was tentatively named CFJY-623. This isolate was identified as Aeromonas veronii based on analysis of its morphological, physiological, and biochemical features, as well as 16S rRNA and gyrB gene sequences. Six virulence genes related to pathogenicity including aerolysin, cytotonic enterotoxins, elastase, glycerophospholipid: cholesterol acyltransferase, lipase, and serine protease were identified in this A. veronii isolate. The median lethal dosage (LD50) of the CFJY-623 isolate for crucian carp was determined as 1.31 × 107 CFU/mL. Artificial experimental infection showed that the CFJY-623 isolate caused considerable histological lesions in the fish, including tissue cell degeneration, necrosis, and inflammatory cell infiltrating. Drug sensitivity testing showed that the isolate was susceptible to aminoglycosides, carbapenemes, and nitrofurans. Exploring its growing features showed that this isolate exhibited a high level of environmental adaptability. These results provided a scientific basis for the identification of A. veronii and treatment for fish infected by this pathogen.

The disease outbreak caused by viral infection and bacterial pathogens has hampered the sustainable development of the gibel carp (Carassius auratus gibelio) industry, lack of monoclonal antibodies against serum immunoglobulin (Ig) of gibel carp has impeded the development of nonfatal immunoassays in detection of pathogen infection and understanding of fish immune response post vaccination. In the present study, serum Ig of gibel carp was purified by a combination of salting-out and DEAE Sepharose Column chromatography. The purified Ig had an apparent molecular weight of 74 kDa and 24 kDa in SDS-PAGE. Three monoclonal antibodies (MAbs) against Ig, designed as 2F4-1G10, 3H3-1E8 and 7H11-1C8, were developed with purified Ig preparations, which were selected on the basis of the indirect enzyme-linked immunosorbent assay (ELISA). Western blotting showed that MAbs 2F4-1G10 and 7H11-1C8 reacted with the heavy chain of IgM, while MAb 3H3-1E8 showed a reaction with the light chain. MAb 7H11-1C8 could react with surface Ig-positive (sIg+) lymphocytes under indirect immunofluorescence assay. Fluorescence-activated cell sorter analysis revealed that the percentage of sIg + lymphocytes were 32.68% in peripheral blood and 12.13% in pronephros. MAb 7H11-1C8 was proven to be effective in detecting the Cyprinid Herpesvirus 2-specific serum Ig, and determining the levels of Aeromonas hydrophila specific Ig in serum and immune organs under different vaccination strategies. • Gibel carp serum Ig was purified and anti-Ig MAbs were developed and characterized. • MAb could be applied in nonfatal serodiagnosis of CyHV-2 infection. • MAb could determine the levels of A. hydrophila specific Ig in fish. [ABSTRACT FROM AUTHOR]

Aeromonas species often cause disease in farmed fish. In the present study, dominant bacteria were isolated from diseased crucian carp (Carassius auratus gibelio). Based on this, a bacterial isolate was tentatively named CFJY-623. This isolate was identified as Aeromonas veronii based on analysis of its morphological, physiological, and biochemical features, as well as 16S rRNA and gyrB gene sequences. Six virulence genes related to pathogenicity including aerolysin, cytotonic enterotoxins, elastase, glycerophospholipid: cholesterol acyltransferase, lipase, and serine protease were identified in this A. veronii isolate. The median lethal dosage (LD50) of the CFJY-623 isolate for crucian carp was determined as 1.31 × 107 CFU/mL. Artificial experimental infection showed that the CFJY-623 isolate caused considerable histological lesions in the fish, including tissue cell degeneration, necrosis, and inflammatory cell infiltrating. Drug sensitivity testing showed that the isolate was susceptible to aminoglycosides, carbapenemes, and nitrofurans. Exploring its growing features showed that this isolate exhibited a high level of environmental adaptability. These results provided a scientific basis for the identification of A. veronii and treatment for fish infected by this pathogen. [ABSTRACT FROM AUTHOR]

Cyprinid herpesvirus II (CyHV-2) is highly contagious and pathogenic to Carassius auratus gibelio (gibel carp), causing enormous economic losses in aquaculture in Yancheng city, Jiangsu province, China; however, to date, there is no effective way to protect C. auratus gibelio from CyHV-2 infection. In this study, a recombinant baculovirus vector vaccine, BacCarassius-D4ORFs, containing a fused codon-optimized sequence D4ORFs comprising the ORF72 (region 1–186 nt), ORF66 (region 993–1197 nt), ORF81 (region 603–783 nt) and ORF82 (region 85–186 nt) genes of CyHV-2, driven by a Megalobrama amblycephala β-actin promoter, was constructed. Then, qPCR, Western blotting and immunofluorescence assays showed that the fused gene D4ORFs was successfully delivered and expressed in fish cells or tissues by transduction with BacCarassius-D4ORFs. The fused gene D4ORFs could not be detected by PCR in the C. auratus gibelio injected with BacCarassius-D4ORFs after 7 weeks. Specific antibody against ORF72 could be detected in the serum of vaccinated C. auratus gibelio by injection with BacCarassius-D4ORFs. Furthermore, when C. auratus gibelio were vaccinated with BacCarassius-D4ORFs via the oral or injection route, followed by challenge with CyHV-2, the relative survival rate of immunized C. auratus gibelio reached 59.3% and 80.01%, respectively. These results suggested that BacCarassius-D4ORFs has the potential to be used as a vector-based vaccine for the prevention and treatment of disease caused by CyHV-2 infection. Image 1 • We construct a recombinant baculovirus vector vaccine BacCarassius-D4ORFs. • Specific antibody could be detected in gibel carp injected with BacCarassius-D4ORFs. • BacCarassius-D4ORFs could effectively protect gibel carp from CyHV-2 infection. [ABSTRACT FROM AUTHOR]

Abstract The present study was conducted to evaluate dietary inosine 5′-monophosphate (5′-IMP) on growth, immune genes expression and disease resistance against Aeromonas hydrophila in juvenile gibel carp (Carassius auratus gibelio var. CAS Ⅲ) (initial body weight: 7.48 g). Six diets were formulated containing exogenous 5′-IMP at three gradient levels (0, 0.1% and 0.2%) in the high dietary fishmeal group (15% fishmeal: D1, D2, D3) and in the high dietary soybean meal group (33% soybean meal: D4, D5, D6). Each diet was randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, fish were exposed to Aeromonas hydrophila challenge. Hematological and immunological responses were analyzed before and after challenge. The results indicated that feeding rate in all 5′-IMP supplemented treatments (D2, D3, D5 and D6) and daily growth coefficient in D5 and D6 were reduced compared with those of respective control treatments (D1 and D4) without 5′-IMP addition (P < 0.05). The cumulative survival rates were numerically improved by dietary 5′-IMP supplementation (P > 0.05). Compared with the respective control treatment, in the high fishmeal group, plasma SOD and MPO were significantly elevated in D3 at the end of feeding trial (P < 0.05), plasma SOD and lysozyme were significantly increased in D3 after bacterial challenge (P < 0.05); in high soybean meal group, plasma lysozyme activity was significantly elevated in D5 post bacterial challenge (P < 0.05). Most of the expression of immune related genes (intelectin, major histocompatibility complex class II β (MHC II β), Complement 3 (C3), Complement component C7-1 (ccC7), lysozyme C, Interleukin 1β (IL-1β), Tumor necrosis factor α1 (TNF-α1), Transforming growth factor-beta (TGF-β) and Interleukin 8 (IL-8)) in spleen, kidney and liver of the fish were significantly affected by supplementation of 5′-IMP at the end of feeding trial and post bacterial challenge. Additionally, adding 5′-IMP in high soybean meal diets exerted further effects of promoting immunity than counterparts in high fishmeal diets. Considering enhanced disease resistance, the immunopotentiation of 5′-IMP was manifested when the addition level was 0.1% in high soybean meal diets and 0.2% in high fishmeal diets. Highlights • Dietary 5′-IMP altered immune-related gene expression in immune organs of gibel carp. • 5′-IMP showed immunoprotection when addition level was 0.1% in high soybean meal diets and 0.2% in high fishmeal diets. • Adding 5′-IMP in high soybean meal diets exerted further effects of promoting immunity than that in high fishmeal diets. [ABSTRACT FROM AUTHOR]

The γ-aminobutyric acid type A (GABAA) receptor is an important pentameric inhibitory neurotransmitter receptor, and the γ2 subunit of this receptor plays a key role in potentiation of the GABAA response. We previously detected that the expression of GABAA receptor in the livers of Carassius auratus gibelio significantly increased after medication (avermectin and difloxacin treatment). In order to better understand the mechanism of action of the GABAA receptor γ2 subunit in the livers of C. auratus gibelio, we constructed a C. auratus gibelio liver cDNA library (the titer value of 1.2 × 106 cfu/mL) and identified the proteins that interact with the GABAA receptor γ2 subunit by using a yeast two-hybrid assay. The yeast two-hybrid screening yielded seven positive clones, namely, prelid3b, cdc42, sgk1, spg21, proteasome, chia.5, and AP-3 complex subunit beta-1, all of which have been annotated by the NCBI database. The functions of these proteins are complex; therefore, additional studies are required to determine the specific interactions of these proteins with the GABAA receptor γ2 subunit in the liver of C. auratus gibelio. Although the interactions identified by the yeast two-hybrid system should be considered as preliminary results, the findings of this study may provide further direction and a foundation for future research focusing on the mechanisms of the GABAA receptor γ2 subunit in C. auratus gibelio livers. [ABSTRACT FROM AUTHOR]

Abstract Background Myxozoa is a well-known economically and ecologically important group of metazoan parasites, phylogenetically related to Cnidaria. High diversity of myxosporeans has been recorded in Russia and China; however, most of the species were solely morphologically characterised. Here, we identified a new gibel carp-infecting Myxobolus species and morphologically and molecularly compared the Russian and Chinese isolates of this new myxosporean. Results Myxobolus pronini n. sp. was found free in the abdominal cavity of Carassius auratus gibelio (Bloch, 1782) in Lake Baikal watershed, Russia, and embedded in the visceral serous membranes of the same fish species in Lake Taibai, Hubei province, China. The morphometric data of the plasmodia and mature spores exhibited some differences between the Russian and Chinese isolates, but SSU rDNA sequences indicated that these two geographical isolates are conspecific. The mature spores from the two locations are obovate in frontal view, with wider anterior than posterior end and lemon-shaped in sutural view. Spores of the Russian isolate were 14.3–16.2 (mean 15.1 ± 0.2) μm long, 9.6–10.8 (10.1 ± 0.1) μm wide and 6.4–7.4 (6.7 ± 0.15) μm thick; those of the Chinese isolate were 13.8–15.6 (14.7 ± 0.24) μm long, 9.6–13.3 (9.6 ± 0.65) μm wide and 6.2–7.2 (6.6 ± 0.16) μm thick. The newly-generated rDNA sequences (including SSU rDNA, ITS and LSU rDNA) from the two isolates represented some variations within the intraspecific range. Homology search by BLAST showed that the newly obtained rDNA sequences do not match any sequences available on GenBank. Phylogenetic analysis based on the aligned partial SSU rDNA sequences indicated that this novel species clustered with several gibel carp-infecting Myxobolus spp. with round anterior end of spores. Additionally, phylogenetic analysis based on all obtained ITS sequences showed that distinct genetic geographical differentiation occurred for this new parasite. Conclusions Myxobolus pronini n. sp. is described by integrating morphological, ecological and molecular evidence. Two geographical isolates of this species showed some morphological and genetic differences but within the intraspecific range of variation.

Purpose. To study the effect of рН values of the aquatic environment on the level of ectoparasite infestation, protein and lysozyme content in organs and serum of some cyprinid species in experimental conditions. Methodology. The objects of the study were yearlings of Cyprinus carpio, Carassius auratus gibelio and Pseudorasbora parva caught in ponds of fish farm “Nyvka” (Kiev region) in spring. Fish were kept in experimental conditions at neutral pH water (6.8-7.2) and a temperature of 17-18оC. To study the changes in the level of fish parasite infestation at different pH values, we used carp yearlings, as an object, the most infected with parasites. Fish were placed in aquariums with water pH of 5.0-5.5 (slightly acidic environment) and 8.5-9.0 (slightly alkaline environment) for 5 days. Thereafter, the ectoparasites were counted on fish body surface and gills. The protein content in serum and tissue extracts of organs (liver, kidney, spleen) of Carassius auratus gibelio and Pseudorasbora parva infected and uninfected ectoparasites, after holding them in slightly acidic or slightly alkaline environment for 8 days, was determined by Lowry’s method, while lysozyme content was determined by a diffusion method on agar. Findings. A comparative assessment of the number of ectoparasites (Ichthyophthirius multifiliis, Trichodina sp., Dactylogyrus sp., Gyrodactylus sp.) on fish body surface and gills, the content of protein and lysozyme in serum and organs at different pH values of aquatic environment has been presented. It was demonstrated that the number of ectoparasites on fish body surface and gills was significantly reduced when keeping the fish in both slightly acidic and slightly alkaline environments. In infected Carassius auratus gibelio, a reduction in the protein and lysozyme content in liver, kidney and serum was observed only in the neutral pH environment compared to uninfected individuals. In the slightly acidic or slightly alkaline environments with a significant reduction in the number of ectoparasites, the protein and lysozyme levels in fish serum and organs were not significantly different from those of non-infected individuals that were kept in water of corresponding pH values. In Pseudorasbora parva with low level of parasite infestation, we did not detect any changes in the protein and lysozyme levels in fish serum and organs in a neutral pH environment. The effect of different pH levels of water on the studied parameters of Pseudorasbora parva showed their significant changes. Originality. For the first time, we demonstrated the change in the level of ectoparasite infestation, protein and lysozyme contents in fish serum and organs (Cyprinus carpio, Carassius auratus gibelio, Pseudorasbora parva), which were kept in the slightly acidic or slightly alkaline aquatic environments. Practical value. The concentration of hydrogen ions, or an aqueous active reaction (pH), plays an important role in the life of fish, their development and in the predisposition to various diseases. The performed studies showed that infestation of fish with parasites can be significantly decreased when changing water pH. This leads to the recovery and restoration of fish normal physiological functions, the impairment of which causes the toxic effects of parasites.

Cyprinid herpesvirus 2 (CyHV-2) infection results in huge economic losses in gibel carp (Carassius auratus gibelio) industry. In this study, we first constructed recombinant plasmids pcORF25 and pcCCL35.2 as DNA vaccine and molecular adjuvant against CyHV-2, respectively, and confirmed that both recombinant plasmids could be effectively expressed in vitro and in vivo. Then, the vaccination and infection experiments (n = 50) were set as seven groups. The survival rate (70%) in ORF25/CCL35.2 group was highest. The highest specific antibody levels were found in ORF25/CCL35.2 group in major immune tissues by qRT-PCR, and confirmed in serum by ELISA assay, antibody neutralization titer, and serum incubation-infection experiments. Three crucial innate immune indices, namely C3 content, lysozyme, and total superoxide dismutase (TSOD) activities, were highest in ORF25/CCL35.2 group in serum. pcORF25/pcCCL35.2 can effectively up-regulate mRNA expressions of some important immune genes (IL-1β, IL-2, IFN-γ2, and viperin), and significantly suppress CyHV-2 replication in head kidney and spleen tissues. The minimal tissue lesions can be seen in ORF25/CCL35.2 group in gill, spleen, and trunk kidney tissues by histopathological examination. The results indicated that the combination of DNA vaccine pcORF25 and molecular adjuvant pcCCL35.2 is an effective method against CyHV-2 infection, suggesting a feasible strategy for the control of fish viral diseases.

Cyprinid herpesvirus 2 (CyHV-2), which infects goldfish and crucian carp causing high mortality, is an emerging viral pathogen worldwide. The genome of CyHV-2 is large and comprises double-stranded DNA, including several genes similar to cyprinid herpesvirus 1, ictalurid herpesvirus-1, cyprinid herpesvirus 3, and ranid herpesvirus-1. Genes of DNA viruses are expressed in three temporal phases: immediate-early (IE), early (E), and late (L) genes. Viral IE genes initiate transcription as soon as the virus enters the host, without viral DNA replication. IE gene products enable the efficient expression of E and L genes or regulate the host to initiate virus replication. In the present study, five IE genes of CyHV-2 were identified, including open reading frame (ORF)54, ORF121, ORF141, ORF147, and ORF155. Time course analysis and reverse transcription polymerase chain reaction confirmed five IE genes, thirty-four E genes, and thirty-nine L genes. In addition, all 150 ORFs identified in the CyHV-2 genome are transcribed, and are expressed in chronological order, similar to other herpesviruses. This study is the first to identify the IE genes of CyHV-2, which will provide more information for viral molecular characterization.

Carassius auratus gibelio is an omnivore favored for its flavor and is commonly used as a benthic species in traditional pond polyculture. This study investigated the effects of common aquaculture stressors, such as high ammonia, high nitrite, high pH, and hypoxia on the aerobic metabolism of C. auratus gibelio. The results showed that the standard metabolic rate (SMR) was positively correlated with ammonia, nitrite, and pH, while the maximum metabolic rate (MMR) was negatively correlated with all four stressors. Thus, aerobic scope (AS) was reduced when C. auratus gibelio was exposed to high ammonia, high nitrite, high pH, and hypoxia. The peak of post-prandial O2 consumption was positively correlated with nitrite, pH, and the occurrence of the peak metabolic rate post-prandial was delayed in high ammonia, high nitrite, hypoxia, and high pH conditions. These findings indicated that, in experimental conditions, exposure to these environmental stressors can influence aerobic metabolism in C. auratus gibelio. With more energy required to maintain standard metabolic rates, less will be available for growth. While the C. auratus gibelio is one of the most hypoxia tolerance species, the reduction we observed in AS caused by stressors that commonly occur in ponds and in nature will likely affect growth in ponds and fitness in nature. These data have provided insight into the optimal, fitness-maximizing thresholds for these common stressors in this species of interest.

A 41-wk growth trial was conducted to evaluate the effects of dietary protein levels on the long-term growth response and fitting growth models of gibel carp (Carassius auratus gibelio) with an initial body weight of 1.85 ± 0.17 g. The dietary protein levels were designed at 320 (P32), 360 (P36), 400 (P40), and 440 g/kg (P44), respectively. The growth curves of the gibel carp for each group were fitted and analyzed with four nonlinear regression models (Gompertz, logistic, von Bertalanffy and Richards). The final body weights (mean ± SD) of the fish were 226 ± 6, 231 ± 7, 242 ± 2, and 236 ± 2 g for P32, P36, P40, and P44, respectively. Feed conversion ratio of P40 and P44 groups was significantly lower than that of P32 and P36 groups (P

Abstract In recent years, Cyprinid herpesvirus 2 (CyHV-2) has severely affected the culture of crucian carp Carassius auratus gibelio , causing massive economic losses. However, the responses of crucian carp during infection with CyHV-2 have not been explored. In this study, physiological and biochemical indicators and enzyme activities of crucian carp before and after infection with CyHV-2 were analyzed. The number of white blood cells in the diseased fish was significantly increased. Compared to control group, red blood cell content, hemoglobin content, mean corpuscular volume, mean corpuscular hemoglobin content and mean corpuscular hemoglobin concentration in the experimental group were significantly decreased. In the diseased fish group, the levels of the glutamic-pyruvic transaminase, glutamic-oxalacetic transaminase, alkaline phosphatase, lactate dehydrogenase and urea nitrogen in the blood were also significantly increased compared to the control group. In addition, the activity of serum total antioxidant capacity, acid phosphatase, glutathione-S transferase and catalase in diseased fish were significantly higher than in the control group. LC-Q/TOF-MS analysis platform was used in this study for the first time to detect changes in the serum metabolome of crucian carp infected with CyHV-2. A total of 79 differential metabolites have been identified. Significant increases in concentrations were found for several carbohydrates (glucose, mannose, ribose, etc.), fatty acids (pentadecanoic acid, arachidonic acid, palmitic acid, eicosapentaenoic acid, hydroxylic tetracarbonate alkenoic acid, linoleic acid and its derivatives) and most of the amino acids and their derivatives. However, guanine, cytosine, uridine and VB2 were significantly decreased. KEGG pathways enrichment showed that amino acid metabolism and lipid metabolism were severely influenced. The above results provide a theoretical basis for the infection mechanism of CyHV-2 Highlights • The WBC was increased in the blood of CyHV-2 infected fish while RBC, HB, MCV, MCH and MCHC were decreased. • ALT, AST, ALP, LDH, BUN, T-AOC, ACP, GST and CAT were significantly increased in the blood of CyHV-2 infected fish. • 79 differential metabolites (75 with significant differences) were identified after CyHV-2 infection. [ABSTRACT FROM AUTHOR]

Abstract Gibel carp (Carassius auratus gibelio), a major aquaculture species in China, has emerged in a seriously epizootic disease caused by Cyprinid herpesvirus 2 (CyHV-2). There are no effective methods to prevent or control this serious disease. Biofloc technology (BFT) can improve water quality, reduce pathogens introduction, enhance cultured species immunity and disease resistance. In this study, a 30-day experiment was conducted to investigate the effect of BFT on innate immune response and disease resistance of gibel carp against CyHV-2 infection. Gibel carp was cultured at different total suspended solid (TSS) concentrations of 10, 300, 600, 800 and 1000 mg L−1, which were named as groups BF0, BF300, BF600, BF800 and BF1000. Results showed that fish in groups BF600/800 had significantly higher weight gain (WG) and specific growth rate (SGR) than them in control group (BF0). The transcriptional levels of seven immune-related genes in BF300/600/800 groups, including myeloid-specific- peroxidase (MPO), keratin 8 (KRT 8), dual specificity phosphatase 1 (DUSP 1), interleukin-11 (IL-11), intelectin (ITLN), purine nucleoside phosphorylase 5α (PNP 5α) and c-type lysozyme (c-lys), were up-regulated significantly compared to BF0 group. Furthermore, cumulative mortality of gibel carp in BF600 group after being challenged with CyHV-2 reduced significantly. In vivo viral replication in kidney demonstrated that CyHV-2 load at 168 h post injection in BF600 group was significantly higher than that in BF0 group. In conclusion, BFT could improve growth, immune response and disease resistance of gibel carp, and the effect was related with TSS concentration. The optimal TSS concentration of 600–800 mg L−1 was recommended in the present study. Highlights • Biofloc technology (BFT) can be applied in gibel carp culture. • Concentration of total suspended solid (TSS) in BFT system could affect growth, immune response and disease resistance of gibel carp. • The optimal TSS concentration of 600–800 mg L−1 was recommended. • BFT could be developed into an alternative aquaculture system for prevention of CyHV-2 infection in gibel carp. [ABSTRACT FROM AUTHOR]

Abstract A 50-day feeding trial was carried out to evaluate the partial replacement of fishmeal by yeast culture (YC) on growth performance, immune response and resistance against Aeromonas hydrophila in gibel carp CAS Ⅲ (Carassius auratus gibelio). Four isonitrogenous and isoenergetic practical diets including a basal diet (the control diet containing 10% fish meal, D0) and three yeast culture diets (substituting 20%, 40%, 60% of the fishmeal in the basal diet, D20, D40 and D60, respectively) were formulated. Each diet was randomly allocated to quadruplicate fish groups (average initial body weight: 28.70 ± 0.03 g) reared in a recirculating system. After the growth trial, bacterial challenge test was conducted. The results showed that no noteworthy variations in feed intake, growth performance and morphology indices were found among groups (P > 0.05). YC Supplemented diet exerted little significant influence on plasma parameters including triglyceride, glucose, creatinine, total protein and urea nitrogen compared with the control group (P > 0.05). No obvious variations were found in activities of plasma lysozyme, IgM, MPO and SOD before challenge test among dietary treatments (P > 0.05), whereas considerable higher value of the foresaid indicators was discovered in D40 after bacteria challenge (P < 0.05). Transcriptional levels of Toll like receptor 2 (TLR2), myeloid differentiation factor 88 (MyD88), Toll/IL-1 receptor domain-containing adaptor protein (TIRAP) and interleukin-1β (IL-1β) in spleen after challenge were significantly up-regulated in D40 compared with D0 (P < 0.05). Cumulative survival rate in D40 and D60 were significantly higher than those in D0 and D20 (P < 0.05). Taken together, yeast culture could be a suitable fishmeal alternative in diets of gibel carp and dietary inclusion of 4 g YC per 100 g diet enhanced the immunity and disease resistance of gibel carp partly via TLR2 pathway. Highlights • Dietary inclusion of 4% of yeast culture improved the immunity of gibel carp associated with TLR2 pathway. • Dietary supplementation of 4% or 6% of yeast culture enhanced the survival of fish against Aeromonas hydrophila. • Yeast culture could be a suitable fishmeal alternative in diets of gibel carp based on growth and immune response. [ABSTRACT FROM AUTHOR]

Abstract Cyprinid herpesvirus 2 (CyHV-2) is a pathogen of herpesviral hematopoietic necrosis disease of crucian carp. Our study aimed to investigate the molecular mechanisms and immune response at the mRNA and protein levels in head kidney during CyHV-2 infection. Three days after infection with CyHV-2, 7085 differentially expressed genes were identified by transcriptome sequencing, of which 3090 were up-regulated and 3995 were down-regulated. And 338 differentially expressed proteins including 277 up-regulated and 61 down-regulated were identified using tandem mass tag labeling followed by liquid chromatography tandem mass spectrometry. Notably, 128 differentially co-expressed genes at mRNA and protein levels (cDEGs) were reliably quantified, including 86 co-up-regulated and 42 co-down-regulated. In addition, 10 cDGEs in the above pathways were selected for qRT-PCR to confirm the validity of the transcriptome and proteome changes by showing that RIG-I, MDA5, LGP2, FAS, PKR and PKZ up-regulated and Integrin α, Integrin β2, NCF2 and NCF4 down-regulated. This indicated that after CyHV-2 infection, the herpes simplex infection pathway, RIG-I like receptor signaling pathway, necroptosis pathway and p53 signaling pathway were activated and the phagosome pathway was suppressed. Our findings reveal the pathogenesis and the host immune mechanism of CyHV-2 infection of crucian carp. Graphical abstract Image 1 Highlights • 7085 transcriptions and 338 proteins were differentially expressed. • 128 differentially co-expressed genes were identified after CyHV-2 infection. • 10 immune proteins are verified in the CyHV-2 infection by Real-time PCR. • Herpes simplex infection pathway and phagosome pathway play an important role in CyHV-2 infection. [ABSTRACT FROM AUTHOR]