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Aquaculture originates from ancient Chinese wisdom, and is considered the most efficient food-producing industry. About 70 years ago, New China proposed an industrial approach to fish production and made a policy decision to begin modern aquaculture development. As one of lucky persons since the early 1980s, I have committed my scholarly career to the studies on genetics and breeding biotechnology of polyploid gibel carp (Carassius gibelio). Here, several significant recent innovations, such as the proposition of the amphitriploid concept, the association of ploidy changes with reproduction transition, the finding of a unique ameiofusiongenesis mode, the establishment of a controllable fertility approach, the creation of intermuscular bonefree mutants, as well as the recreation of desirable goldfish, are introduced and emphasized from an active participant of these innovations. Additionally, some modern innovations and contributions are also highlighted in other aspects of aquaculture including feed development, disease control, facilities and equipment upgrading, as well as paradigm and mode changes. This comprehensive synthesis of ancient Chinese wisdom and modern innovations seeks to provide valuable insights into the field from a historical basis. [ABSTRACT FROM AUTHOR]

This study investigated the responses of glucolipid metabolism in gibel carp, the CAS III strain (A strain, 7.14 ± 0.23 g) and the Dongting strain (DT strain, 7.72 ± 0.54 g), following acute hypoxia/reoxygenation. The effects of hypoxia (0.39 ± 0.02 mg/L) and reoxygenation (8.30 ± 0.30 mg/L) were examined in both strains after exposure for 2 h. The results revealed significantly enhanced PI3K/AKT pathway and AMPK/HIF-1α pathways, along with upregulated expression of glucose-6-phosphatase (g6pase) and lipid synthesis-related genes (acc and fas) in both gibel carp strains following acute hypoxia (P < 0.05). The observed increase in plasma glucose levels during acute hypoxia may be related to elevated expression of g6pase (P < 0.05). Regarding the genotype, the A strain exhibited significantly higher expression of glucose metabolism-related genes (pk and pepck) in the liver compared to the DT strain (P < 0.05). Conversely, the expression of lipid metabolism-related genes (hsl, lpl, pparα, cpt1a, and aco3) were significantly lower in the A strain compared to the DT strain (P < 0.05). In both strains of gibel carp, reoxygenation resulted in significant activation of the PI3K/AKT and AMPK/mTOR pathways, accompanied by upregulated expression of glucose metabolism-related genes (gk, 6pfk, foxo1a, fbpase, and pepck) and lipid synthesis-related genes (srebp-1, acly, and acc) (P < 0.05). Notably, the A strain exhibited increased transcripts of glucose metabolism-related genes (gk, pk, foxo1a, g6pase, and pepck) and lipid metabolism-related genes (acly, fas, and cpt1a) compared to the DT strain (P < 0.05). Overall, this study revealed distinct regulation patterns of glucolipid metabolism in the gibel carp with different genotype under acute hypoxia/reoxygenation.

This study explored the impacts of supplementation of different levels of coated methionine (Met) in a high-plant protein diet on growth, blood biochemistry, antioxidant capacity, digestive enzymes activity and expression of genes related to TOR signaling pathway in gibel carp (Carassius auratus gibeilo). A high-plant protein diet was formulated and used as a basal diet and supplemented with five different levels of coated Met at 0.15, 0.30, 0.45, 0.60 and 0.75%, corresponding to final analyzed Met levels of 0.34, 0.49, 0.64, 0.76, 0.92 and 1.06%. Three replicate groups of fish (initial mean weight, 11.37 ± 0.02 g) (20 fish per replicate) were fed the test diets over a 10-week feeding period. The results indicated that with the increase of coated Met level, the final weight, weight gain (WG) and specific growth rate initially boosted and then suppressed, peaking at 0.76% Met level (P< 0.05). Increasing dietary Met level led to significantly increased muscle crude protein content (P< 0.05) and reduced serum alanine aminotransferase activity (P< 0.05). Using appropriate dietary Met level led to reduced malondialdehyde concentration in hepatopancreas (P< 0.05), improved superoxide dismutase activity (P< 0.05), and enhanced intestinal amylase and protease activities (P< 0.05). The expression levels of genes associated with muscle protein synthesis such as insulin-like growth factor-1, protein kinase B, target of rapamycin and eukaryotic initiation factor 4E binding protein-1 mRNA were significantly regulated, peaking at Met level of 0.76% (P< 0.05). In conclusion, supplementing optimal level of coated Met improved on fish growth, antioxidant capacity, and the expression of TOR pathway related genes in muscle. The optimal dietary Met level was determined to be 0.71% of the diet based on quadratic regression analysis of WG. [ABSTRACT FROM AUTHOR]

Frequent outbreaks of emerging infectious diseases in fish, such as Carassius auratus herpesvirus (CaHV) infection has caused great economic losses in China. However, the lack of a sensitive cell culture system has limited studies of CaHV. In the present study, a new cell line (gibel carp skin cell, GiCS) derived from gibel carp (Carassius gibelio) skin tissue was established to create a valuable tool for research of the virus. The GiCS cells consisted mainly of epithelial-like cells, which grew well at 25 °C in L-15 medium supplemented with 10-20% fetal bovine serum. Chromosomal analysis revealed that the skin cell line remained amphitriploid, with most chromosome counts being 156 (54%). The GiCS cells can be efficiently transfected and expressed exogenous genes. In particular, the GiCS cells showed high susceptibility to CaHV infection, which was confirmed by virus infection tests, detection of viral gene expression, and ultrastructural observation. To our knowledge, it is the first cell line that is highly permissive to CaHV infection. In addition, the cells also showed susceptibility to several aquatic animal viruses from different families including Iridoviridae, Rhabdoviridae, and Reoviridae. In conclusion, these results indicated that the establishment of the GiCS cell line is a significant advance that will be beneficial to future studies of CaHV and other aquatic animal viruses. [ABSTRACT FROM AUTHOR]

An eight-week experiment was conducted to study the effects of dietary ferroporphyrin (FPR) supplementation on growth performance, antioxidant capacity, immune response, and oxygen-carrying capacity in gibel carp. The results demonstrated that the addition of FPR increased the moisture content of the whole fish body. Supplementation with 0.01% FPR significantly increased the plasma albumin (ALB), total protein (TP), and total cholesterol (TC) contents. The addition of 0.03% and 0.04% FPR significantly increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, respectively, while the glucose (GLU), TC, and total triglyceride (TG) levels showed opposite trends. In terms of antioxidant capacity, the 0.03% and 0.04% dietary FPR supplementation increased malondialdehyde (MDA) levels. The activity of glutathione peroxidase (GPx) exhibited an opposite trend to MDA levels. The supplementation of 0.03% of FPR resulted in a notable reduction in mRNA expression levels of nrf2, keap1, cat, and gpx. Regarding immunity, 0.01% FPR supplementation down-regulated the expression levels of il-1β mRNA, while 0.02% FPR down-regulated il-6 and nf-κb expression levels. Furthermore, 0.02% FPR supplementation significantly up-regulated the il-10 mRNA expression levels. In terms of oxygen-carrying capacity, high levels of FPR (0.03% and 0.04%) were found to influence the epo and vegf mRNA expression. In conclusion, the incorporation of dietary 0.01–0.02% FPR improved the immune system of gibel carp without affecting their antioxidant and oxygen-carrying capacity. However, supplementation with higher levels of FPR (0.03–0.04%) led to decreased antioxidant and oxygen-carrying capacity.

Successful invasive non-native fish species can cause enormous damage to native biodiversity. In mainland Europe, the introduction of the gibel carp (Carassius gibelio) has led to a decline in populations of the formerly widespread native crucian carp (C. carassius). Both invasive and native species develop two phenotypes, namely stunted and deep-bodied, which depend on the intensity of competition and predation in the water body. The deep-bodied phenotype is associated with a more diverse fish community composition, can attain large sizes and is very attractive to recreational anglers. This study analysed trends in the record sizes of native crucian carp and invasive gibel carp (individuals close to the maximum attainable size of the species) reported by recreational anglers over the last 50 years in Czechia, recording the invasion of gibel carp from its beginnings to the fully established population phase. The study provides circumstantial evidence that gibel carp is behind transition from the relative abundance of large crucian carp to near extirpation, while large gibel carp have taken over the reports of record catches in the genus Carassius. This indicates that the crucian carp, which is currently classified as critically endangered in the Red List of Czechia, has very limited possibilities to realise its deep-bodied phenotype. It also shows the potential of using data from recreational anglers for mapping invasion processes and as a source of relatively localised information on endangered species. [ABSTRACT FROM AUTHOR]

A 10-week feeding trial was conducted to elucidate the effects of coated amino acids on growth performance, intestinal health, and muscle quality of gibel carp (Carassius auratus gibelio) fed with low protein diet. A total of 450 carps (initial body weight of 15.67 g ± 0.04) were selected and randomly assigned into 6 groups, with each group consisting of three replicates and 25 fish per replicate. Six experimental diets were: control group (NP, 31.44% CP), low protein group (LP, 28.69% CP), low protein supplemented with crystalline methionine (CrM), crystalline methionine and crystalline lysine (CrML), coated methionine (CoM) or coated methionine and coated lysine (CoML). The results indicated that compared to the NP group, the LP group showed no significant difference in weight gain, specific growth rate, feed conversion ratio, viscerosomatic index, and condition factor (P > 0.05) but had a significant decrease in whole body crude fat content and increase in moisture content (P < 0.05). The hepatosomatic index in the CoML group was significantly lower than the LP group (P

This study explored the impacts of supplementation of different levels of coated methionine (Met) in a high-plant protein diet on growth, blood biochemistry, antioxidant capacity, digestive enzymes activity and expression of genes related to TOR signaling pathway in gibel carp (Carassius auratus gibeilo). A high-plant protein diet was formulated and used as a basal diet and supplemented with five different levels of coated Met at 0.15, 0.30, 0.45, 0.60 and 0.75%, corresponding to final analyzed Met levels of 0.34, 0.49, 0.64, 0.76, 0.92 and 1.06%. Three replicate groups of fish (initial mean weight, 11.37 ± 0.02 g) (20 fish per replicate) were fed the test diets over a 10-week feeding period. The results indicated that with the increase of coated Met level, the final weight, weight gain (WG) and specific growth rate initially boosted and then suppressed, peaking at 0.76% Met level (P< 0.05). Increasing dietary Met level led to significantly increased muscle crude protein content (P< 0.05) and reduced serum alanine aminotransferase activity (P< 0.05). Using appropriate dietary Met level led to reduced malondialdehyde concentration in hepatopancreas (P< 0.05), improved superoxide dismutase activity (P< 0.05), and enhanced intestinal amylase and protease activities (P< 0.05). The expression levels of genes associated with muscle protein synthesis such as insulin-like growth factor-1, protein kinase B, target of rapamycin and eukaryotic initiation factor 4E binding protein-1 mRNA were significantly regulated, peaking at Met level of 0.76% (P< 0.05). In conclusion, supplementing optimal level of coated Met improved on fish growth, antioxidant capacity, and the expression of TOR pathway related genes in muscle. The optimal dietary Met level was determined to be 0.71% of the diet based on quadratic regression analysis of WG.

Myxobolus lentisuturalis is a myxosporean parasite infecting the musculature both of goldfish (Carassius auratus auratus) and gibel carp (Carassius auratus gibelio). The species was originally described in China from gibel carp that is a common fish for sport fishing in Hungary meanwhile is one of the most popular farmed fish in China due to its high demand. Eighteen gibel carp with distortions were collected from a barrage pond in southern Hungary. All fish had large humps in the dorsolateral region due to infection of the muscle between the head and the dorsal fin. The swollen degenerated tissue was filled with myxozoan spores, which were collected for morphological and molecular studies. By size and morphology, the spores were consistent with morphological description of M. lentisuturalis. Histopathological examination showed that the formation of plasmodia containing myxospores leads to severe destruction of muscle tissue. The 18S ribosomal DNA and 28S ribosomal DNA data of the samples presented matched with previous sequences of M. lentisuturalis in GenBank. Phylogenetic analyses confirmed that our sequences belong to a monophyletic group with them supported by a high bootstrap. This study highlights the occurrence of a highly pathogenic myxozoan, M. lentisuturalis in Hungary as a new geographical location. [ABSTRACT FROM AUTHOR]

Cyprinid herpesvirus II (CyHV-2), a highly contagious pathogen of gibel carp (Carassius auratus gibelio), causes herpesviral hematopoietic necrosis disease (HVHND) and enormous financial losses. However, there is limited information available regarding the changes in plasma biochemical and immunological parameters and the response characteristics of Toll-like receptor 2 (TLR2) and Toll-like receptor 9 (TLR9) in gibel carp after CyHV-2 infection. To address this knowledge gap, a sub-lethal CyHV-2 infection was conducted in gibel carp, and the sample was collected daily from 1 to 7 days post infection. The plasma biochemical analyses showed significant decreases in the content of glucose, total cholesterol (TCHO), and total protein (TP), along with marked increases in the level of uric acid, urea, creatinine (CREA), Complement 3 (C3), immunoglobulin D (IgD), and immunoglobulin M (IgM) as well as in the activity of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) in the infected group. Compared with the control group, the concentration of cortisol, triglyceride (TG), and Complement 4 (C4) had no noticeable alterations in the infected group. Real-time quantitative PCR analysis showed significant upregulation of TLR2 and TLR9 mRNA expression in the spleen, kidney, brain, liver, intestine, and gill post CyHV-2 infection. Interestingly, a time- and tissue-dependent expression profile has been comparatively observed for TLR2 and TLR9 in the above tissues of gibel carp after CyHV-2 infection, suggesting distinct roles between TLR2 and TLR9 in antiviral response to CyHV-2 infection. Overall, our results demonstrated that CyHV-2 infection led to the disruption of the physiological metabolic process and damage to the liver and kidney, and induced different spatiotemporal expression patterns of TLR2 and TLR9, ultimately stimulating antiviral response via innate and adaptive immune system. These findings may provide a deeper understanding of the host immunity response to CyHV-2 infection and offer novel perspectives for the prevention and treatment and therapeutic drug development against CyHV-2. [ABSTRACT FROM AUTHOR]

Previous nutritional studies have shown that intermediate metabolism in early fish development is highly plastic, and thus we hypothesized that there may be an early programming effect of a hyperglucidic diet on carbohydrate utilization in gibel carp. To test our hypothesis, gibel carp CAS Ⅴ (mean body weight: 0.10 g) were fed a high-carbohydrate/low protein (HC/LP) or low carbohydrate/high protein (LC/HP) diet for three weeks, and then were fed with normal feed for 12 weeks and a hyperglucidic diet for one week. We found that early HC/LP stimulus inhibited growth performance but altered the expression of glucose metabolism genes. After long-term feeding on the normal diet, the effects of early HC/LP stimulus were eliminated; these involved plasma metabolites, hepatic cholesterol, glycogen and triglyceride content, and glucose and lipid metabolism. However, the early HC stimulus group showed a better ability to maintain plasma glucose hemostasis when again given the HC diet. The capacity of carbohydrate and lipid metabolism in juvenile gibel carp was improved in the early HC diet group, as indicated by upregulated expression of genes related to glycolysis, lipid transport (gk, akt, srebp1, acc, fas, hsl, and acly) and downregulated expression of genes involved in gluconeogenesis (fbpase). Moreover, the early HC diet significantly upregulated AKT protein expression levels. The DNA methylation levels of akt in the HC/LP group were significantly lower than those in the LC/HP group. Overall, the study suggests that early HC stimulus in juvenile gibel carp can result in better carbohydrate utilization through DNA methylation of critical elements in the insulin signaling pathway.

Polyinosinic-polycytidylic acid (poly I:C) is a synthesized analogue of viral double-strand RNA and considered as a potential immunostimulant in aquaculture. MicroRNAs (miRNAs) have been reported to play important roles in the development of the immune system and in regulation of host antiviral responses. In our earlier study, it was found that poly I:C pre-treatment could stimulate the resistance against cyprinid herpesvirus 2 (CyHV-2) infection and enhance the antiviral immune response in gibel carp. To understand the role of miRNAs in regulating the host response to poly I:C treatment, we investigated the expression profiles of miRNAs in the head kidney of poly I:C-treated gibel carp with small RNA sequencing technology. When compared with the untreated group, a total of 24 differentially expressed miRNAs were identified in the poly I:C-stimulated fish, among which, 7 and 17 miRNAs were upregulated and downregulated, respectively. Analysis of target genes of these differentially expressed miRNAs found that most targeted mRNAs were involved in catalytic activity, peptidase activity and endopeptidase activity, and were enriched in the metabolic, protein processing in endoplasmic reticulum and oxidative phosphorylation signaling pathways, suggesting that poly I:C could alter the expression of metabolism-related miRNAs in the kidney of gibel carp. Besides, it was noted that some immune-related miRNAs, including inflammation-related miRNAs (miR-192 and miR-731) and interferon-related miRNAs (miR-194a and miR-122), were downregulated after poly I:C treatment. In summary, it was found that poly I:C could regulate the cellular levels of specific miRNAs involved in metabolism and immune responses in the head kidney of gibel carp, which may increase the capacity of the immune cells to fight against pathogens infection.

Accurate recording of growth indicators for aquaculture species at different stages is essential for evaluating aquaculture production effectiveness and the rationality of feed formulations. Due to their convenience and non-invasiveness, weight, length, and condition factor are commonly used to assess the growth of aquaculture species. However, fish growth indicators, can vary significantly with age structure and feed components (nutrition), and relying on a single indicator may lead to misjudgments. In this study, we investigated the growth indicators of Gibel carp (Carassius auratus gibelio var. CAS V) at different growth stages (juvenile and adult) and different feed formulations. Meanwhile, the fish weight–length relationship ( W = b L a ) was used to assess the growth indicators. The results showed that the weight–length relationship of Gibel carp varied significantly with age and feed formulation. Additionally, the condition factor calculated depended on the weight–length relationship being more similar with weight and length change trend than the condition factor was measured. Weight analysis indicated that weight, length, depth, body width, and carcass ratio had higher weights when analyzing fish growth. Therefore, during aquaculture production, fish growth evaluating requires considering diverse indicators such as weight, length, body depth, body width, and carcass ratio, as well as the condition factor, to avoid misjudging the actual growth situation. Meanwhile, the use of the condition factor should consider the sufficient number of data and whether the assumptions (such as being in an isometric growth period) are met. [ABSTRACT FROM AUTHOR]

Heavy metal toxicity is a significant threat to human health and the environment. Contamination of the food chain with heavy metals in water sources may impact the health of consumers adversely. This study aimed to determine the concentrations of Pb, Cd, Cr, Cu, and Zn in the invasive fish species Carassius gibelio inhabiting two important lakes in Türkiye: Lake Beyşehir and Lake Eğirdir, from the Lake District Region and assess any health risks posed by the consumption of these species. For this purpose, C. gibelio species were obtained from two lakes in dry and rainy seasons and heavy metal concentrations were determined via ICP-OES analyses. The Cd concentrations in the muscle samples obtained from both lakes were below the analysis limits. The mean heavy metal concentrations (mg/kg) in the Beyşehir and Eğirdir lake samples were found as Pb: 0.32, Cr: 0.09, Cu: 0.52, and Zn: 6.88 and Pb: 0.88, Cr: 0.08, Cu: 0.46, and Zn: 12.6, respectively. The average heavy metal concentrations in the muscle tissues were below the national/international legislation limits, and the estimated daily intake (EDI), target hazard quotients (THQs), total THQs (TTHQs), and carcinogenic rates (CRs) did not exceed these limits. The results suggested that the consumption of these invasive fish species from these two lakes might not pose any potential health risk for consumers. Transference values (TF) for the digestive tract were also calculated, and biomagnification was determined for Pb, Cd, and Cr. Risk assessment studies are very important in terms of evaluating the effects of fish consumption on human health via applying different indices. This is the first study in which heavy metal concentrations were determined simultaneously in Lake Beyşehir and Lake Eğirdir, and the public health risk of consuming their invasive fish species was estimated. [ABSTRACT FROM AUTHOR]

An acute elevation in temperature impacts fish physiology and in turn causes an alteration in growth performance. This study investigated the effect of acute thermal stress on skeletal muscle growth and quality in gibel carp (Carassius gibelio). The gibel carp were randomly assigned to three temperature treatments, 20 °C, 26 °C, and 32 °C, for 168 h. The muscular quality characteristics and the expressions of the genes related to muscle growth were assessed at 0 h, 1 h, 12 h, 24 h, 72 h, and 168 h. The muscle nutrient content was significantly higher in the 20 °C treatment, and the muscle was more tender and elastic. The gene expression levels of the MRFs family were significantly upregulated and then gradually decreased after 1 h. The expression level of MSTN-2 was increased in the 32 °C treatment at 168 h, in support of the slow growth rate under acute thermal stress. It is implied that gibel carp could adapt to acute thermal stress to a certain extent. Acute thermal stress, however, eventually led to a decrease in muscle growth rate and quality. [ABSTRACT FROM AUTHOR]

Cyprinid herpesvirus II (CyHV-2), a highly contagious pathogen of gibel carp (Carassius auratus gibelio), causes herpesviral hematopoietic necrosis disease (HVHND) and enormous financial losses. However, there is limited information available regarding the changes in plasma biochemical and immunological parameters and the response characteristics of Toll-like receptor 2 (TLR2) and Toll-like receptor 9 (TLR9) in gibel carp after CyHV-2 infection. To address this knowledge gap, a sub-lethal CyHV-2 infection was conducted in gibel carp, and the sample was collected daily from 1 to 7 days post infection. The plasma biochemical analyses showed significant decreases in the content of glucose, total cholesterol (TCHO), and total protein (TP), along with marked increases in the level of uric acid, urea, creatinine (CREA), Complement 3 (C3), immunoglobulin D (IgD), and immunoglobulin M (IgM) as well as in the activity of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) in the infected group. Compared with the control group, the concentration of cortisol, triglyceride (TG), and Complement 4 (C4) had no noticeable alterations in the infected group. Real-time quantitative PCR analysis showed significant upregulation of TLR2 and TLR9 mRNA expression in the spleen, kidney, brain, liver, intestine, and gill post CyHV-2 infection. Interestingly, a time- and tissue-dependent expression profile has been comparatively observed for TLR2 and TLR9 in the above tissues of gibel carp after CyHV-2 infection, suggesting distinct roles between TLR2 and TLR9 in antiviral response to CyHV-2 infection. Overall, our results demonstrated that CyHV-2 infection led to the disruption of the physiological metabolic process and damage to the liver and kidney, and induced different spatiotemporal expression patterns of TLR2 and TLR9, ultimately stimulating antiviral response via innate and adaptive immune system. These findings may provide a deeper understanding of the host immunity response to CyHV-2 infection and offer novel perspectives for the prevention and treatment and therapeutic drug development against CyHV-2.

Invasive alien species pose a serious threat to biodiversity. They frequently compete with native species for resources, resulting in the decline or extinction of the latter.Native crucian carp (Carassius carassius) faces a severe decline in European waters and has become critically endangered in many European countries. Possible ecological mechanisms of the rapid decline of the crucian carp attributable to resource competition with the invasive Carassius gibelio were identified. A field study was combined with a controlled experiment to compare (i) standard length–weight relationships and growth patterns in 12 Czech and Swedish ponds in which the species occur alone or in syntopy, and (ii) individual growth and food utilization under the same conditions.The growth increment of C. gibelio was greater than that of C. carassius under the same experimental conditions (mean increase in weight: C. gibelio, 21.7%; C. carassius, 5.2%; increase in standard length: C. gibelio, 6.3%; C. carassius, 2.0%), suggesting that C. gibelio uses food resources more efficiently than C. carassius does. Moreover, larger C. carassius individuals did not grow, whereas growth of C. gibelio individuals was largely independent of standard length.Field data suggested that C. gibelio grew faster and were heavier than C. carassius of the same standard length in four Czech ponds where they occurred together. Individual weight‐at‐length declined in C. carassius in the presence of C. gibelio, especially in more dense populations, whereas the weight‐at‐length of C. gibelio remained similar.Taken together, these results imply that C. gibelio has better competitive abilities for food than C. carassius and provide novel support for the long‐standing hypothesis that the introduction and spread of C. gibelio causes the decline of C. carassius in European waters. [ABSTRACT FROM AUTHOR]

An eight-week experiment was conducted to study the effects of dietary ferroporphyrin (FPR) supplementation on growth performance, antioxidant capacity, immune response, and oxygen-carrying capacity in gibel carp. The results demonstrated that the addition of FPR increased the moisture content of the whole fish body. Supplementation with 0.01% FPR significantly increased the plasma albumin (ALB), total protein (TP), and total cholesterol (TC) contents. The addition of 0.03% and 0.04% FPR significantly increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, respectively, while the glucose (GLU), TC, and total triglyceride (TG) levels showed opposite trends. In terms of antioxidant capacity, the 0.03% and 0.04% dietary FPR supplementation increased malondialdehyde (MDA) levels. The activity of glutathione peroxidase (GPx) exhibited an opposite trend to MDA levels. The supplementation of 0.03% of FPR resulted in a notable reduction in mRNA expression levels of nrf2 , keap1 , cat , and gpx. Regarding immunity, 0.01% FPR supplementation down-regulated the expression levels of il-1β mRNA, while 0.02% FPR down-regulated il-6 and nf-κb expression levels. Furthermore, 0.02% FPR supplementation significantly up-regulated the il-10 mRNA expression levels. In terms of oxygen-carrying capacity, high levels of FPR (0.03% and 0.04%) were found to influence the epo and vegf mRNA expression. In conclusion, the incorporation of dietary 0.01-0.02% FPR improved the immune system of gibel carp without affecting their antioxidant and oxygen-carrying capacity. However, supplementation with higher levels of FPR (0.03-0.04%) led to decreased antioxidant and oxygen-carrying capacity.

Accurate recording of growth indicators for aquaculture species at different stages is essential for evaluating aquaculture production effectiveness and the rationality of feed formulations. Due to their convenience and non-invasiveness, weight, length, and condition factor are commonly used to assess the growth of aquaculture species. However, fish growth indicators, can vary significantly with age structure and feed components (nutrition), and relying on a single indicator may lead to misjudgments. In this study, we investigated the growth indicators of Gibel carp (Carassius auratus gibelio var. CAS V) at different growth stages (juvenile and adult) and different feed formulations. Meanwhile, the fish weight–length relationship (W=bLa) was used to assess the growth indicators. The results showed that the weight–length relationship of Gibel carp varied significantly with age and feed formulation. Additionally, the condition factor calculated depended on the weight–length relationship being more similar with weight and length change trend than the condition factor was measured. Weight analysis indicated that weight, length, depth, body width, and carcass ratio had higher weights when analyzing fish growth. Therefore, during aquaculture production, fish growth evaluating requires considering diverse indicators such as weight, length, body depth, body width, and carcass ratio, as well as the condition factor, to avoid misjudging the actual growth situation. Meanwhile, the use of the condition factor should consider the sufficient number of data and whether the assumptions (such as being in an isometric growth period) are met.

Cyprinid herpesvirus 2 (CyHV-2) causes herpesviral hematopoietic necrosis (HVHN) disease outbreaks in farmed Cyprinid fish, which leads to serious economic losses worldwide. Although oral vaccination is considered the most suitable strategy for preventing infectious diseases in farmed fish, so far there is no commercial oral vaccine available for controlling HVNN in gibel carp (C. auratus gibelio). In the present study, we developed for the first time an oral vaccine against CyHV-2 by using yeast cell surface display technology and then investigated the effect of this vaccine in gibel carp. Furthermore, the protective efficacy was evaluated by comparing the immune response of a single vaccination with that of a booster vaccination (booster-vaccinated once 2 weeks after the initial vaccination). Critically, the activities of immune-related enzymes and genes expression in vaccine group, especially in the booster vaccine group, were higher than those in the control group. Moreover, strong innate and adaptive immune responses could be elicited in both mucosal and systemic tissues after receipt of the oral yeast vaccine. To further understand the protective efficacy of this vaccine in gibel carp, we successfully developed the challenge model with CyHV-2. Our results showed the relative percent survival was 66.7% in the booster vaccine group, indicating this oral yeast vaccine is a promising vaccine for controlling CyHV-2 disease in gibel carp aquaculture. [ABSTRACT FROM AUTHOR]

Gyrodactylid monogeneans are common parasites of teleost fishes characterized by high host specificity. Host specificity and its underlying mechanisms of monogenean have been always a fascinating issue that has attracted considerable attention from researchers. However, the molecular mechanism responsible for the host specificity of monogenean is still not yet fully understood. In this study, the susceptibility to Gyrodactylus kobayashii of different species or varieties in the genus Carassius was investigated. Furthermore, the proteome changes in the skin mucus of resistant and susceptible fish were analyzed by Tandem Mass Tags (TMT) quantitative proteomics method. The experimental results indicated that G. kobayashii was found in 12 varieties of goldfish and ChangFeng C. auratus gibelio with different degrees of infection percentage, while no G. kobayashii was found in C. auratus gibelio var. CAS Ⅴ. Population dynamics of G. kobayashii on red white common goldfish and C. auratus gibelio var. CAS Ⅴ showed distinct trends in the in vivo infection experiment. These results demonstrated C. auratus gibelio var. CAS Ⅴ is a resistant fish to G. kobayashii. Proteomic analysis revealed that 41 differentially expressed proteins (DEPs), including 25 up-regulated and 16 down-regulated proteins, were identified. Bioinformatics analysis indicated these DEPs were involved in multiple biological functions including immunity, metabolism, and signal transduction. Among them, some immune-related proteins, such as cadherin-1, serotransferrin, and glutathione transferase in the fish mucus might be potential determinants of the host susceptibility to G. kobayashii. Also, some structural and energy metabolism-related DEPs, such as small muscular protein, keratin and vitelline membrane outer layer protein served as a source of nutrition and might also affect host susceptibility. Overall, this study not only provided systematic protein information of crucian carp skin mucus but also identified some potential candidate proteins that might be related to host susceptibility to G. kobayashii.

Abstract Background Fatty liver has become a main problem that causes huge economic losses in many aquaculture modes. It is a common physiological or pathological phenomenon in aquaculture, but the causes and occurring mechanism are remaining enigmatic. Methods Each three liver samples from the control group of allogynogenetic gibel carp with normal liver and the overfeeding group with fatty liver were collected randomly for the detailed comparison of histological structure, lipid accumulation, transcriptomic profile, latent pathway identification analysis (LPIA), marker gene expression, and hepatocyte mitochondria analyses. Results Compared to normal liver, larger hepatocytes and more lipid accumulation were observed in fatty liver. Transcriptomic analysis between fatty liver and normal liver showed a totally different transcriptional trajectory. GO terms and KEGG pathways analyses revealed several enriched pathways in fatty liver, such as lipid biosynthesis, degradation accumulation, peroxidation, or metabolism and redox balance activities. LPIA identified an activated ferroptosis pathway in the fatty liver. qPCR analysis confirmed that gpx4, a negative regulator of ferroptosis, was significantly downregulated while the other three positively regulated marker genes, such as acsl4, tfr1 and gcl, were upregulated in fatty liver. Moreover, the hepatocytes of fatty liver had more condensed mitochondria and some of their outer membranes were almost ruptured. Conclusions We reveal an association between ferroptosis and fish fatty liver for the first time, suggesting that ferroptosis might be activated in liver fatty. Therefore, the current study provides a clue for future studies on fish fatty liver problems.

More and more evidences proved that deltamethrin (Del) exposure induced adverse effects and damaged immune function to the aquatic animals in the parasite killing process with increasing insecticide application. However, little is currently known of the negative effect on mucosal immunity, especially in gills tissue. Therefore, this study was aimed to reveal the tissue injury and immunotoxicity in the gill of gibel carp following acute deltamethrin exposure. The LC50 of deltamethrin on gibel carp at 96 h was determined to be 6.194 μg/L, and then juvenile gibel carp (Carassius auratus gibelio) (8.8 ± 1.0 g) were exposed to four Del exposure groups (0.61, 1.22, 2.44, and 4.88 μg/L) for 12 h and 24 h. We measured the lysozyme (LYZ) contents and myeloperoxidase (MPO) activities and found that with increased concentration of Del exposure, the LYZ contents were found to increase in the 1.22 μg/L Del group initially significantly and then gradually significantly decrease in the 4.88 μg/L Del group. And the activities of MPO were significantly lifted in a dose-dependent manner. The histological analysis showed that Del exposure caused serious desquamation and necrosis in the surface of epithelial cells, accompanied by interlamellar cellular mass degenerative. In addition, the mucous cells were significantly decreased in the high Del concentration group (2.44 μg/L and 4.88 μg/L Del group) by AB-PAS staining. Additionally, totally 2857 DEGs (including 1624 up-regulated and 1233 down-regulated genes) were identified between the control group and 4.88 μg/L Del exposure group using transcriptional analysis. Among these, some genes involved in innate immune molecules, complement activation, apoptosis-related molecules, cytokine, and adaptive immune molecules, were also down-regulated. Importantly, we found immune system process and tumor necrosis factor receptor (superfamily) binding pathways were downregulated based on the GO and KEGG enrichment analysis. Meanwhile, we detected the expression of pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, and IL-8), anti-inflammatory cytokines (TGF-β), LYZ, IgM, and Hsp70 in the gills tissue at 12 h and 24 h after Del exposure, which were consistent with our sequencing results. Collectively, these results demonstrated that the gills injury and immunotoxicity were induced by Del exposure and provided novel insight for explaining to some extent why Del-exposure fish are more susceptible to concurrent or secondary viral or bacterial infections.

This study investigated the effects of dietary Flos populi extract (FPE) on the growth, antioxidation capability, innate immune response, and disease resistance in gibel carp. A total of 480 fish were fed with five different diets containing 0, 0.5, 1.0, 1.5, or 2.0 g kg−1 FPE (designated as control, D0.5, D1.0, D1.5, or D2.0 groups) for 45 days. The fish were challenged with A. hydrophila after the feeding trial. Compared with the control, the feed efficiency (FE), weight gain (WG), final body weight (FBW), and specific growth rate (SGR) were significantly improved in groups D1.0 and D1.5. Dietary FPE significantly increased serum superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities, as well as glutathione (GSH) content. The contents of protein carbonyl (PCC) and malondialdehyde (MDA) in serum decreased significantly. Additionally, FPE supplementation in diets resulted in significant improvement in serum lysozyme (LZM) and myeloperoxidase (MPO) activities, as well as immunoglobulin M (IgM) and complement 3 (C3) concentrations. The hepatic antioxidant enzymes (CAT and SOD) activities increased, whereas content of MDA decreased in fish treated with dietary FPE than those of control both pre- and post-challenged. After 12 h-challenge, an obvious downregulation of hepatic Kelch-like-ECH-associated protein 1 (Keap1), splenic tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-1β, and toll-like receptor 2 (TLR2) mRNA levels was observed in fish treated with dietary FPE, whereas hepatic Nrf2 transcription level was upregulated compared to the control. Furthermore, compared to group D0.5, higher relative percent survival (RPS) was observed in gibel carp fed dietary 1.0–2.0 g/kg FPE. Our results reveal that FPE supplemented diet has a stimulatory effect on antioxidant capacity and nonspecific immune response, along with improved growth performance and enhanced resistance against A. hydrophila infection in juvenile gibel carp. [ABSTRACT FROM AUTHOR]

The study was to investigate the beneficial effect of four amino acids and two classical attractants on the feeding of gibel carp, to develop a compound attractant formula with strong attractiveness for gibel carp angling. The experiment obtained the optimal feeding-promoting concentration of each substance through agar starch granule feed intake behavior experiment. The optimal feeding concentration of the selected material was orthogonal designed, and nine compound formulas were obtained. Through the further comparison of the feeding experiments, the compound formula with strong attractiveness for gibel carp was obtained. The experimental results showed that the relative intake of 1×10-2 mol/L DMPT, 1×10-2 mol/L arginine and 1×10-1 mol/L alanine was significantly higher than that of the same test substance at the other three concentrations (P<0.05), and the relative food intake was more than 1.5, which could effectively promote the feeding of gibel carp. By the orthogonal design, the compound formula 5 composed of the 1×10-2 mol/L DMPT, 1×10-2 mol/L arginine and 5×10-2 mol/L alanine showed the highest relative intake with a value of 4.3, the ingestion rate of which was significantly higher than that of the three monomer attractants of 10-2 mol/L DMPT, arginine and 10-2 mol/L alanine (P<0.05). The study indicates that the compound attractant composed of the single attractants shows the synergetic effect to improve the feeding activity of gibel carp. [ABSTRACT FROM AUTHOR]

Src homology region 2 domain-containing phosphatase 1 (SHP1), encoded by the protein tyrosine phosphatase nonreceptor type 6 (ptpn6) gene, belongs to the family of protein tyrosine phosphatases (PTPs) and participates in multiple signaling pathways of immune cells. However, the mechanism of SHP1 in regulating fish immunity is largely unknown. In this study, we first identified two gibel carp (Carassius gibelio) ptpn6 homeologs (Cgptpn6-A and Cgptpn6-B), each of which had three alleles with high identities. Then, relative to Cgptpn6-B , dominant expression in adult tissues and higher upregulated expression of Cgptpn6-A induced by polyinosinic-polycytidylic acid (poly I:C), poly deoxyadenylic-deoxythymidylic (dA:dT) acid and spring viremia of carp virus (SVCV) were uncovered. Finally, we demonstrated that Cg SHP1-A (encoded by the Cgptpn6-A gene) and Cg SHP1-B (encoded by the Cgptpn6-B gene) act as negative regulators of the RIG-I-like receptor (RLR)-mediated interferon (IFN) response via two mechanisms: the inhibition of Ca TBK1-induced phosphorylation of Ca MITA shared by Cg SHP1-A and Cg SHP1-B, and the autophagic degradation of Ca MITA exclusively by Cg SHP1-A. Meanwhile, the data support that Cg SHP1-A and Cg SHP1-B have sub-functionalized and that Cg SHP1-A overwhelmingly dominates Cg SHP1-B in the process of RLR-mediated IFN response. The current study not only sheds light on the regulative mechanism of SHP1 in fish immunity, but also provides a typical case of duplicated gene evolutionary fates. [ABSTRACT FROM AUTHOR]

Src homology region 2 domain-containing phosphatase 1 (SHP1), encoded by the protein tyrosine phosphatase nonreceptor type 6 (ptpn6) gene, belongs to the family of protein tyrosine phosphatases (PTPs) and participates in multiple signaling pathways of immune cells. However, the mechanism of SHP1 in regulating fish immunity is largely unknown. In this study, we first identified two gibel carp (Carassius gibelio) ptpn6 homeologs (Cgptpn6-A and Cgptpn6-B), each of which had three alleles with high identities. Then, relative to Cgptpn6-B, dominant expression in adult tissues and higher upregulated expression of Cgptpn6-A induced by polyinosinic-polycytidylic acid (poly I:C), poly deoxyadenylic-deoxythymidylic (dA:dT) acid and spring viremia of carp virus (SVCV) were uncovered. Finally, we demonstrated that CgSHP1-A (encoded by the Cgptpn6-A gene) and CgSHP1-B (encoded by the Cgptpn6-B gene) act as negative regulators of the RIG-I-like receptor (RLR)-mediated interferon (IFN) response via two mechanisms: the inhibition of CaTBK1-induced phosphorylation of CaMITA shared by CgSHP1-A and CgSHP1-B, and the autophagic degradation of CaMITA exclusively by CgSHP1-A. Meanwhile, the data support that CgSHP1-A and CgSHP1-B have sub-functionalized and that CgSHP1-A overwhelmingly dominates CgSHP1-B in the process of RLR-mediated IFN response. The current study not only sheds light on the regulative mechanism of SHP1 in fish immunity, but also provides a typical case of duplicated gene evolutionary fates.

Abstract Background Accompanied with rapid growth and high density aquaculture, gibel carp has been seriously threatened by Carassius auratus herpesvirus (CaHV) since 2012. In previous study, distinct CaHV resistances and immune responses were revealed in the diseased individuals of three gibel carp gynogenetic clones (A+, F and H). However, little is known about the gene expression changes in the survivors after CaHV challenge, particularly their differences of innate and adaptive immune system between susceptible clone and resistant clone. Results We firstly confirmed the CaHV carrier state in the survivors of three gibel carp clones after CaHV challenge by evaluating the abundances of five CaHV genes. The assay of viral loads indicated the resistant clone H possessed not only stronger resistance but also higher tolerance to CaHV. Then, 2818, 4047 and 3323 differentially expressed unigenes (DEUs) were screened from the head-kidney transcriptome profiles of survivors compared with controls from clone A+, F and H. GO and KEGG analysis suggested that a persistent immune response might sustain in resistant clone H and F, while susceptible clone A+ had a long-term impact on the circulatory system which was consistent with the major symptoms of bleeding caused by CaHV. Among the top 30 enriched pathways of specifically up-regulated DEUs in respective clones, 26, 7 and 15 pathways in clone H, F and A+ were associated with infections, diseases, or immune-related pathways respectively. In addition, 20 pathways in clone F belonged to “metabolism” or “biogenesis”, and 7 pathways involved in “circulatory system” were enriched in clone A+. Significantly, we revealed the differential expression changes of IFN system genes and immunoglobulin (Ig) genes among the survivors of three clones. Finally, myosins and Igs were identified as co-expression modules which were positively or negatively correlated to CaHV viral loads respectively. Conclusions Our results revealed the common and distinct gene expression changes in immune and circulatory system in the survivors of three gibel carp gynogenetic clones with different CaHV resistances. The current study represents a paradigm of differential innate and adaptive immune reactions in teleost, and will be beneficial to the disease-resistance breeding of gibel carp.

Background: Fatty liver has become a main problem that causes huge economic losses in many aquaculture modes. It is a common physiological or pathological phenomenon in aquaculture, but the causes and occurring mechanism are remaining enigmatic. Methods: Each three liver samples from the control group of allogynogenetic gibel carp with normal liver and the overfeeding group with fatty liver were collected randomly for the detailed comparison of histological structure, lipid accumulation, transcriptomic profile, latent pathway identification analysis (LPIA), marker gene expression, and hepatocyte mitochondria analyses. Results: Compared to normal liver, larger hepatocytes and more lipid accumulation were observed in fatty liver. Transcriptomic analysis between fatty liver and normal liver showed a totally different transcriptional trajectory. GO terms and KEGG pathways analyses revealed several enriched pathways in fatty liver, such as lipid biosynthesis, degradation accumulation, peroxidation, or metabolism and redox balance activities. LPIA identified an activated ferroptosis pathway in the fatty liver. qPCR analysis confirmed that gpx4, a negative regulator of ferroptosis, was significantly downregulated while the other three positively regulated marker genes, such as acsl4, tfr1 and gcl, were upregulated in fatty liver. Moreover, the hepatocytes of fatty liver had more condensed mitochondria and some of their outer membranes were almost ruptured. Conclusions: We reveal an association between ferroptosis and fish fatty liver for the first time, suggesting that ferroptosis might be activated in liver fatty. Therefore, the current study provides a clue for future studies on fish fatty liver problems. [ABSTRACT FROM AUTHOR]

Evolutionary fates of duplicated genes have been widely investigated in many polyploid plants and animals, but research is scarce in recurrent polyploids. In this study, we focused on foxl2 , a central player in ovary, and elaborated the functional divergence in gibel carp (Carassius gibelio), a recurrent auto-allo-hexaploid fish. First, we identified three divergent foxl2 homeologs (Cgfoxl2a-B , Cgfoxl2b-A , and Cgfoxl2b-B), each of them possessing three highly conserved alleles and revealed their biased retention/loss. Then, their abundant sexual dimorphism and biased expression were uncovered in hypothalamic–pituitary–gonadal axis. Significantly, granulosa cells and three subpopulations of thecal cells were distinguished by cellular localization of Cg Foxl2a and Cg Foxl2b, and the functional roles and the involved process were traced in folliculogenesis. Finally, we successfully edited multiple foxl2 homeologs and/or alleles by using CRISPR/Cas9. Cgfoxl2a-B deficiency led to ovary development arrest or complete sex reversal, whereas complete disruption of Cgfoxl2b-A and Cgfoxl2b-B resulted in the depletion of germ cells. Taken together, the detailed cellular localization and functional differences indicate that Cgfoxl2a and Cgfoxl2b have subfunctionalized and cooperated to regulate folliculogenesis and gonad differentiation, and Cgfoxl2b has evolved a new function in oogenesis. Therefore, the current study provides a typical case of homeolog/allele diversification, retention/loss, biased expression, and sub-/neofunctionalization in the evolution of duplicated genes driven by polyploidy and subsequent diploidization from the recurrent polyploid fish. [ABSTRACT FROM AUTHOR]

Leucine has been reported to regulate key metabolic pathways, including growth, immunity and antioxidative defence. To study the effects of dietary leucine supplementation in a carbohydrate‐rich diet on juvenile gibel carp (Carassius auratus gibelio var. CAS III), an 8‐week feeding trial was conducted on gibel carp juveniles reared on an experimental wheat meal‐rich diet (40%) with varying leucine contents (0.87%, 1.23%, 1.68%, 2.10%, 2.41% and 2.83%). No significant changes in growth performance were observed regardless of leucine levels (p > 0.05). However, proper leucine levels (1.68% and 2.10%) could increase the accumulation of whole‐body crude protein and decrease the accumulation of crude lipid. Furthermore, significant liver tissue damage occurred at 1.23% and 1.68% dietary leucine levels, whereas 2.10% and 2.41% dietary leucine could improve the antioxidant capacity at the end of the 8‐week feeding trial. 1.68% and 2.10% dietary leucine levels could alleviate the hyperglycaemia caused by high carbohydrate intake after the 8‐week feeding trial, as well as the elevated glucose content after starvation, to maintain normal metabolic conditions. Supplementation with leucine could significantly downregulate IL‐1β, TNF‐α1, MyD88 and TIRAP mRNA levels during the 8‐week feeding trial and after starvation for 48 h. In conclusion, 2.10%–2.41% leucine contents in a carbohydrate‐rich diet could benefit muscle protein deposition, hyperglycaemia and hyperlipidaemia alleviation, and results in non‐specific immunity improvement. [ABSTRACT FROM AUTHOR]

This study assessed the nutritional potential of supplementing the practical diets for gibel carp (Carassius auratus gibelio var. CAS V) with a blend of fermented plant meal. The fermented plant meal (FPM) comprised mixed fermentation of rapeseed meal (RM), sprayed corn husk (SCH), rice bran (RB), palm meal (PM) and soybean meal (SM) in the proportion of 30:25:25:15:5. Four experimental diets were including a basal diet (the control diet, Con) and three FPM diets (supplementing 3 g, 5 g and 8 g FPM per 100 g diet in the basal diet, FPM3, FPM5 and FPM8, respectively). Each diet was randomly allotted to triplicate fish tanks where each tank had 25 fish weighing 28.00 ± 0.02 g. Fish from each group were fed twice per day until apparent satiation for 60 days. From the results, gibel carp from the FPM5 group had significantly higher feed efficiency and specific growth rate despite having significantly lower feeding rate than the control group. Fish from FPM5 group had significantly higher hepatosomatic index and viscera somatic index than those from FPM3 group. Meanwhile, serum antioxidants (including aspartate aminotransferase, catalase, glutathione peroxidase, superoxide dismutase and malondialdehyde) and intestinal digestive enzymes (including chymotrypsin, trypsin and amylase) of fish increased proportionately to amount of FPM in the diet. Fish fed on FPM5 diet had significantly higher expression of TOR and IGF-1 in the liver than those fed on the control diet. Further, supplemented with 8% of FPM significantly increased the relative mRNA abundance of hepatopancreas GH and S6K1. These results reveal that moderate level of dietary FPM significantly enhanced growth performance, antioxidant capacity, digestive enzymes activities and the expression of TOR signaling pathway genes of juvenile gibel carp, and dietary supplementation of 5% FPM is recommended for the juveniles base on the performance of growth and antioxidant properties.

Background In recent years, there are growing concerns about pharmaceutically active compounds (PhACs) in natural ecosystems. These compounds have been found in natural waters and in fish tissues worldwide. Regarding their growing distribution and abundance, it is becoming clear that traditionally used risk assessment methodologies and ecotoxicological studies have limitations in several respects. In our study a new, combined approach of environmental impact assesment of PhACs has been used. Methods In this study, the constant watercourses of the suburban region of the Hungarian capital (Budapest) were sampled, and the body shape and scale shape of three fish species (roach Rutilus rutilus, chub Squalius cephalus, gibel carp Carassius gibelio) found in these waters were analyzed, based on landmark-based geometric morphometric methods. Possible connections were made between the differences in body shape and scale shape, and abiotic environmental variables (local- and landscape-scale) and measured PhACs. Results Significant connections were found between shape and PhACs concentrations in several cases. Despite the relatively large number of compounds (54) detected, citalopram, propranolol, codeine and trimetazidine significantly affected only fish body and scale shape, based on their concentrations. These four PhACs were shown to be high (citalopram), medium (propranolol and codeine), and low (trimetazidine) risk levels during the environmental risk assessment, which were based on Risk Quotient calculation. Furthermore, seven PhACs (diclofenac, Estrone (E1), tramadol, caffeine 17α-Ethinylestradiol (EE2), 17α-Estradiol (aE2), Estriol (E3)) were also categorized with a high risk level. However, our morphological studies indicated that only citalopram was found to affect fish phenotype amongst the PhACs posing high risk. Therefore, our results revealed that the output of (traditional) environmental/ecological risk assessment based on ecotoxicological data of different aquatic organisms not necessarily show consistency with a “real-life” situation; furthermore, the morphological investigations may also be a good sub-lethal endpoint in ecotoxicological assessments.

Background: In recent years, there are growing concerns about pharmaceutically active compounds (PhACs) in natural ecosystems. These compounds have been found in natural waters and in fish tissues worldwide. Regarding their growing distribution and abundance, it is becoming clear that traditionally used risk assessment methodologies and ecotoxicological studies have limitations in several respects. In our study a new, combined approach of environmental impact assesment of PhACs has been used. Methods: In this study, the constant watercourses of the suburban region of the Hungarian capital (Budapest) were sampled, and the body shape and scale shape of three fish species (roach Rutilus rutilus, chub Squalius cephalus, gibel carp Carassius gibelio) found in these waters were analyzed, based on landmark-based geometric morphometric methods. Possible connections were made between the differences in body shape and scale shape, and abiotic environmental variables (local-and landscape-scale) and measured PhACs. Results: Significant connections were found between shape and PhACs concentrations in several cases. Despite the relatively large number of compounds (54) detected, citalopram, propranolol, codeine and trimetazidine significantly affected only fish body and scale shape, based on their concentrations. These four PhACs were shown to be high (citalopram), medium (propranolol and codeine), and low (trimetazidine) risk levels during the environmental risk assessment, which were based on Risk Quotient calculation. Furthermore, seven PhACs (diclofenac, Estrone (E1), tramadol, caffeine 17a-Ethinylestradiol (EE2), 17a-Estradiol (aE2), Estriol (E3)) were also categorized with a high risk level. However, our morphological studies indicated that only citalopram was found to affect fish phenotype amongst the PhACs posing high risk. Therefore, our results revealed that the output of (traditional) environmental/ecological risk assessment based on ecotoxicological data of different aquatic organisms not necessarily show consistency with a "real-life" situation; furthermore, the morphological investigations may also be a good sub-lethal endpoint in ecotoxicological assessments. [ABSTRACT FROM AUTHOR]

This study explored the impacts of supplementation of different levels of coated methionine (Met) in a high-plant protein diet on growth, blood biochemistry, antioxidant capacity, digestive enzymes activity and expression of genes related to TOR signaling pathway in gibel carp ( Carassius auratus gibeilo). A high-plant protein diet was formulated and used as a basal diet and supplemented with five different levels of coated Met at 0.15, 0.30, 0.45, 0.60 and 0.75%, corresponding to final analyzed Met levels of 0.34, 0.49, 0.64, 0.76, 0.92 and 1.06%. Three replicate groups of fish (initial mean weight, 11.37 ± 0.02 g) (20 fish per replicate) were fed the test diets over a 10-week feeding period. The results indicated that with the increase of coated Met level, the final weight, weight gain (WG) and specific growth rate initially boosted and then suppressed, peaking at 0.76% Met level ( P < 0.05). Increasing dietary Met level led to significantly increased muscle crude protein content ( P < 0.05) and reduced serum alanine aminotransferase activity ( P < 0.05). Using appropriate dietary Met level led to reduced malondialdehyde concentration in hepatopancreas ( P < 0.05), improved superoxide dismutase activity ( P < 0.05), and enhanced intestinal amylase and protease activities ( P < 0.05). The expression levels of genes associated with muscle protein synthesis such as insulin-like growth factor-1, protein kinase B, target of rapamycin and eukaryotic initiation factor 4E binding protein-1 mRNA were significantly regulated, peaking at Met level of 0.76% ( P < 0.05). In conclusion, supplementing optimal level of coated Met improved on fish growth, antioxidant capacity, and the expression of TOR pathway related genes in muscle. The optimal dietary Met level was determined to be 0.71% of the diet based on quadratic regression analysis of WG., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Du, Lin, Shao, Zhao, Xu, de Cruz and Xu.)

Copyright of Journal of Hydrobiology 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.)

Gelatin and carboxymethyl cellulose (CMC) were often used as binders due to their binding ability. To investigate the effects of gelatin and CMC supplementation on feed quality, intestinal ultrastructure and growth performance of gibel carp, six pelleted feed were formulated: control; supplemented with gelatin (10 g/kg, 30 g/kg and 50 g/kg); and supplemented with CMC (10 g/kg and 30 g/kg). Increased gelatin supplementation levels reduced feed solubility and pellet softening (p <.05) and decreased chemical oxygen demand in the surrounding water after pellets were immersed (p <.05). Increased levels of gelatin supplementation enhanced digesta viscosity and reduced intestinal microvilli length and digestive enzymes activities (chymotrypsin and amylase; p <.05) of fish. Fish‐fed diets supplemented with 30 g/kg gelatin had higher levels of plasma total free amino acids and glucose (p <.05) than fish fed 10 g/kg and 50 g/kg gelatin. Feed supplemented with 10 g/kg CMC were softer than those supplemented with 30 g/kg CMC (p <.05); fish‐fed diets supplemented with 10 g/kg CMC had longer intestinal microvilli (p <.05) than fish fed 30 g/kg CMC. Thus, our results indicated that either gelatin or CMC is applicable to supplement in the feed for improving feed quality and without negative effect on growth performance of gibel carp. [ABSTRACT FROM AUTHOR]

This study was aimed to evaluate the effects of partial replacement of fish meal by fermented moringa leaves (FMLs) on growth performance, serum biochemistry, antioxidant status, nonspecific immunity, and resistance against Aeromonas hydrophila in juvenile gibel carp (Carassius auratus gibelio var. CAS III). Four isonitrogenous and isoenergetic balanced diets, including three FML diets (substituting 20%, 40%, 60% of the fish meal in basal diet, F20, F40 and F60, respectively) and a basal diet (a diet containing 10% fish meal) were used. Each diet was randomly allocated to four fish groups (F20, F40, F60 and control) reared in a recirculating system. After 50 days of the feeding trial, fish were challenged by A. hydrophila. The result revealed that final mean body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed efficiency (FE) and survival rate (SR) were significantly increased (P < 0.05) in F20 and F40 groups compared with the control group. Decreased hepatosomatic index (HSI), body crude lipid, serum aspartate transaminase (AST) and serum alanine aminotransferase (ALT) activities, and increased serum alkaline phosphatase (AKP) and serum glutathione peroxidase (GPx) activities were observed in F40 and F60 groups compared with the control and F20 groups. All FMLs-supplemented groups increased (P < 0.05) serum superoxide dismutase (SOD), catalase (CAT) and lysozyme activities, complement component 3 (C3) and serum immunoglobulin M (IgM) concentration, or decreased serum malondialdehyde (MDA) and protein carbonyl (PCC) contents (P < 0.05). After the challenge test, the significant downregulation of toll-like receptors2 (TLR2), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-8 mRNA transcription levels was observed in spleens of FMLs supplemented groups. Dietary F40 and F60 showed higher (P < 0.05) relative percent survival (RPS) (48.72% and 43.59%, respectively) against A. hydrophila infection than control. These results indicate that, as a dietary fish meal substitute, FMLs enhance the growth, and antioxidant and immune response, and regulate the expression of immune-related genes and increase disease resistance against A. hydrophila via TLR2 pathway in gibel carp, with greatest effects of 40% fish meal substitution. • 40% of fishmeal replaced by FMLs could improve growth performance of gibel carp. • Dietary FMLs could improve antioxidant capability and the health of the body. • Dietary FMLs could improve immune response and disease resistance against A. hydrophila. • 10 g FMLs per 100 g diet is recommended to be added in feed for gibel carp. [ABSTRACT FROM AUTHOR]

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Geotrichum candidum is a filamentous fungus mostly used in the dairy industry for cheese ripening and flavoring. The current study was designed to evaluate the potential probiotics effect of dietary supplementation of G. candidum on growth, digestive enzymes activities, gut microbiota and immune-related gene expression and disease resistance in Gibel carp CAS Ⅲ (Carassius auratus gibelio) against A. hydrophila infections. For this purpose, 420 healthy fish (initial body weight: 7.09 ± 0.02g) were randomly divided into 7 feeding groups in triplicates of 20 fish in each tank. Seven isocaloric and isonitrogenous diets were prepared, supplemented with 6 different doses of G. candidum viz; C: 0, T1:106, T2:107, T3:108, T4:109, T5:1010, T6:1011 CFU/kg diet and fed to fish twice a day for 60 days. Results showed significantly higher weight gain (WG) and feed efficiency (FE) in groups fed 106 and 108 CFU/kg diet compared to the control (P < 0.05). All G. candidum fed groups showed higher intestinal α-amylase activity (P < 0.05) while no difference in lipase and trypsin activity compared to the control group. Before challenge test, gut microbial diversity analysis revealed relatively more abundance of bacteria belonging to phylum Proteobacteria, Actinobacteria, Firmicutes and Bacteriodetes in group fed G. candidum supplemented diet and higher percentage of pathogenic bacteria belonging to order Aeromonadales and Vibrionales in control post-challenge. After challenge test immune response expressed numerically higher survival rate (P > 0.05) and significantly higher (P < 0.05) Respiratory Burst Activity(RBA), Immunoglobulin M level (IgM), Aspartate Transaminase activity (AST) and improved (P > 0.05) lysozyme activity, and Alanine Transaminase activity (ALT) in groups fed 106 and 108 CFU/kg G. candidum supplemented diet. The expression of immune related gene (IL-I β, TNF- α, HSP70 and TLR-2) in liver of the fish were significantly affected (P < 0.05) by supplementation of G. candidum post bacterial challenge. The results showed that G. candidum is a potential probiotic as it could improve feed utilization, immunity and cause no harmful effects on growth of gibel carp at higher supplementation levels. The productive results can be achieved by using the lower dose as 106–108 CFU/kg diet. • Dietary Geotrichum candidum supplementation exerted good effect on growth and feed utilization in gibel carp. • Geotrichum candidum supplementation improves gut microbial balance of gibel carp. • Geotrichum candidum supplementation at lower levels promoted immunity against A. hydrophila infections. [ABSTRACT FROM AUTHOR]

A six‐week feeding trial was conducted to determine the effects of different concentrations of fucoidan (1 g/kg, 10 g/kg and 30 g/kg; w/w) from Undaria pinnatifida on gibel carp (Carassius auratus gibelio). Our results demonstrated that 30 g/kg fucoidan significantly increased (p <.05) growth performance, intestinal digestive enzyme activities, acid phosphatase activity and immunoglobulin M content. Histological examinations revealed that gibel carp receiving 30 g/kg fucoidan had significant higher abundance of mucin‐containing goblet cells in middle and distal intestine as compared with control treatment (p <.05). Intestinal microbiota analysis showed that 30 g/kg fucoidan supplementation significantly increased (p <.05) the abundance of Cetobacterium and Aeromonas, but lowered (p <.05) the prevalence of pathogenic bacteria Plesiomonas and a mucin‐degrading bacterium Mucinivorans. Furthermore, RNA‐seq and RT‐qPCR analysis indicated that 30 g/kg fucoidan caused significant changes (p <.05) in the expression of genes involved in immune regulation (such as interleukin‐8 and cyclooxygenase), signal transduction (such as phosphatidylinositol‐4,5‐bisphosphate 3‐kinase and protein kinase B) and nutrition utilization (maltase–glucoamylase and muscarinic acetylcholine receptor 3). Together, the current study shows that fucoidan supplementation could elevate the activity of intestinal digestive enzymes, modulate intestinal microbial communities and potentiate a higher state of immune readiness, which might consequently improve growth performance and intestine health status of gibel carp. [ABSTRACT FROM AUTHOR]

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]

Abstract Background Gibel carp is an important aquaculture species in China, and a herpesvirus, called as Carassius auratus herpesvirus (CaHV), has hampered the aquaculture development. Diverse gynogenetic clones of gibel carp have been identified or created, and some of them have been used as aquaculture varieties, but their resistances to herpesvirus and the underlying mechanism remain unknown. Results To reveal their susceptibility differences, we firstly performed herpesvirus challenge experiments in three gynogenetic clones of gibel carp, including the leading variety clone A+, candidate variety clone F and wild clone H. Three clones showed distinct resistances to CaHV. Moreover, 8772, 8679 and 10,982 differentially expressed unigenes (DEUs) were identified from comparative transcriptomes between diseased individuals and control individuals of clone A+, F and H, respectively. Comprehensive analysis of the shared DEUs in all three clones displayed common defense pathways to the herpesvirus infection, activating IFN system and suppressing complements. KEGG pathway analysis of specifically changed DEUs in respective clones revealed distinct immune responses to the herpesvirus infection. The DEU numbers identified from clone H in KEGG immune-related pathways, such as “chemokine signaling pathway”, “Toll-like receptor signaling pathway” and others, were remarkably much more than those from clone A+ and F. Several IFN-related genes, including Mx1, viperin, PKR and others, showed higher increases in the resistant clone H than that in the others. IFNphi3, IFI44-like and Gig2 displayed the highest expression in clone F and IRF1 uniquely increased in susceptible clone A+. In contrast to strong immune defense in resistant clone H, susceptible clone A+ showed remarkable up-regulation of genes related to apoptosis or death, indicating that clone A+ failed to resist virus offensive and evidently induced apoptosis or death. Conclusions Our study is the first attempt to screen distinct resistances and immune responses of three gynogenetic gibel carp clones to herpesvirus infection by comprehensive transcriptomes. These differential DEUs, immune-related pathways and IFN system genes identified from susceptible and resistant clones will be beneficial to marker-assisted selection (MAS) breeding or molecular module-based resistance breeding in gibel carp.

Abstract Cyprinid herpesvirus 2 (CyHV‐2) infection is detrimental to gibel carp health and may result in severe economic loss in freshwater aquaculture. However, information regarding the interaction of this pathogen with the aquatic environment is scarce. In this study, quantitative polymerase chain reaction (qPCR) and high‐throughput sequencing were used to determine the abundances of pathogens and bacterial community compositions in two aquaculture ponds in Jiangsu Province, China. The results indicate that the concentrations of six selected pathogens were higher in the water than in the sediment and that these concentrations peaked during disease outbreak. In total, 8,326 and 18,244 operational taxonomic units were identified from water and sediment samples, respectively. The dominant phyla were Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and Chlorobi in water samples and Proteobacteria, Firmicutes, Actinobacteria, Chloroflexi, and Bacteroidetes in sediment samples. Bacterial communities were similar at the phylum level in different ponds, although significant differences were observed at the genus level. In addition, bacterial diversity was associated with environmental factors (temperature, chemical oxygen demand, NO2−‐N, NO3−‐N, and NH4+‐N) in the pond where the outbreak occurred. Additionally, CyHV‐2 abundance was positively correlated with dissolved oxygen levels and Aeromonas spp. abundance in pond water (p

To test the hypothesis that effects of dietary carbohydrate and lipid concentrations on growth performance, feeding utilization, glucose and lipid metabolism in gibel carp A strain may be differ from F strain, these two strain of gibel carp were fed with one of three different isonitrogenous diets: HCLL (45% carbohydrate, 2% lipid), MCML (30% carbohydrate, 8% lipid), or LCHL (15% carbohydrate, 14% lipid). After 8 weeks, the HCLL-fed fish had the highest hepatosomatic index, hepatic crude lipid levels, and triglyceride levels and lipid retention efficiency. Enhanced lipogenesis and lipid uptake potential were observed in fish fed HCLL and MCML diets. Moreover, increases in glucose transport (glut2, P = 0.003) and glycolysis (gk, P = 0.012; 6pfk, P = 0.005) in livers of both strains were induced by the high-carbohydrate diet. Genotype-specific effect was identified on plasma lipid content. Plasma triglyceride levels were also greater in the F strain than in the A strain. Furthermore, the F strain had higher levels of fatty acid β-oxidation and glycolysis compared with the A strain. Nutrient retention was affected (P < 0.05) by the interaction between genotype and diet, implied dietary carbohydrate played a vital role in lipid accumulation in gibel carp. As dietary lipids increased, the F strain exhibited better feed utilization and a higher PRE than the A strain. However, the A strain had better growth performance. Overall, the F strain had better glucose uptake, glycolysis potential, and lipid utilization ability than the A strain.

The lack of practical control measures for pharyngeal myxobolosis is becoming an important limiting factor for the sustainable development of the gibel carp (Carassius auratus gibelio) culture industry in China. Myxobolus honghuensis has been identified as the causative agent of this pandemic disease, which exclusively infects the pharynx of gibel carp, a potential important mucosal lymphoid-associated tissue (MLAT). Myxozoa generally initiate invasion through the mucosal tissues of fish, where some of them also complete their sporogonial stages. However, the pharynx-associated immune responses of teleost against myxosporeans infection remain unknown. Here, a de novo transcriptome assembly of the pharynx of gibel carp naturally infected with M. honghuensis was performed for the first time, using RNA-seq. Comparative analysis of severely infected and mildly infected pharyngeal tissues (SI group and MI group) from the same fish individuals and control pharyngeal tissues (C group) from the uninfected fish was carried out to investigate the potential mucosal immune function of the fish pharynx, and characterize the panoramic picture of pharynx local mucosal immune responses of gibel carp against the M. honghuensis infection. A total of 242,341 unigenes were obtained and pairwise comparison resulted in 13,009 differentially-expressed genes (DEGs) in the SI/C group comparison, 6014 DEGs in the MI/C group comparison, and 9031 DEGs in the SI/MI group comparison. Comprehensive analysis showed that M. honghuensis infection elicited a significant parasite load-dependent alteration of the expression of numerous innate and adaptive immune-related genes in the local lesion tissue. Innate immune molecules, including mucins, toll-like receptors, C-type lectin, serum amyloid A, cathepsins and complement components were significantly up-regulated in the SI group compared with the C group. Up-regulation of genes involved in apoptosis signaling pathway and the IFN-mediated immune system were found in the SI group, suggesting these two pathways played a crucial role in innate immune response to M. honghuensis infection. Up-regulation of chemokines and chemokine receptors and the induction of the leukocyte trans-endothelial migration pathways in the severely and mildly infected pharynx suggested that many leucocytes were recruited to the local infected sites to mount a strong mucosal immune responses against the myxosporean infection. Up-regulation of CD3D, CD22, CD276, IL4/13A, GATA3, arginase 2, IgM, IgT and pIgR transcripts provided strong evidences for the presence of T/B cells and specific mucosal immune responses at local sites with M. honghuensis infection. Our results firstly demonstrated the mucosal function of the teleost pharynx and provided evidences of intensive local immune defense responses against this mucosa-infecting myxosporean in the gibel carp pharynx. Pharyngeal myxobolosis was shaped by a prevailing anti-inflammatory response pattern during the advanced infection stages. Further understanding of the functional roles of fish immune molecules involved in the initial invasion and/or final sporogony site may facilitate future development of control strategies for this myxobolosis. • This study firstly demonstrated the mucosal function of the teleost pharynx and provided evidences of intensive local immune defense responses against the mucosa-infecting myxosporean in the gibel carp pharynx. • Our results provided the first evidence that IgT production occurred in the pharynx of teleost fish. • Pharyngeal myxobolosis was shaped by a prevailing anti-inflammatory pattern during the advanced stage of M. honghuensis infection. [ABSTRACT FROM AUTHOR]

Non-native freshwater fish introductions can have direct and indirect negative effects on native flora and fauna, ecosystems, and national economies. Although invasions are paradoxical from an evolutionary standpoint, population genetics could be useful to understand invasion scenarios of non-native species. One of the most common introduced fish in Europe and Turkey is the gibel carp Carassius gibelio , which was first introduced from East Asia in the 17th century. To find out the origin and distribution pattern and characterise the genetic variation of gibel carp in Turkey, the aim of this study was to identify haplotype the species' diversity and distribution in the country. Three mitochondrial (COI , Cyt-b and D-loop) and one nuclear (ITS1) DNA markers were used in 20 populations sampled from 18 different geographic locations, resulting in eight newly-identified haplotypes. The present results: (i) suggest high genetic diversity across regions at both the mitochondrial (29 haplotypes, h = 0.9058, π = 0.0152) and nuclear (3 haplotypes, h = 0.6365, π = 0.0094) level; (ii) confirm previous findings that this species may have entered Turkey directly either from its native or through its invasive range; (iii) suggest that, given the distribution of the identified haplotypes by geographic location, the majority of individuals not only originated from the northern (European) part of Turkey but also from the southern (Mediterranean) part of the country. Understanding the genetic characterisation of gibel carp can contribute to more efficient management actions for this species, including prevention of (multiple) introductions and eradication/control of those populations with relatively low genetic diversity. [ABSTRACT FROM AUTHOR]

A 40‐day experiment was conducted to investigate the effects of two filamentous microalgae as feed ingredients on growth performance, tissue fatty acid profiles, pigmentation and immunity of gibel carp (204.83 ± 2.17 g, mean ± SD). Three diets (control, Oedocladium sp. and Tribonema sp.) were formulated. In the control diet, no microalgal meal was added and into the Oedocladium and Tribonema diets were added 40 g/kg Oedocladium sp. meal and 50 g/kg Tribonema sp. meal, respectively. Compared to the control, the addition of Oedocladium sp. and Tribonema sp. had significant effects on tissue fatty acid profiles, antioxidant capacity and immunity without compromising growth, body composition and pigmentation. The addition of Tribonema sp. and Oedocladium sp. significantly increased the EPA, DHA profiles and the ratio of n‐3/n‐6 polyunsaturated fatty acids, and simultaneously decreased the n‐6 polyunsaturated fatty acids profile in fish muscles. Moreover, addition of Tribonema sp. to the diet significantly increased muscle palmitoleic profile and EPA + DHA contents. Furthermore, the addition of either microalga significantly increased the total superoxide dismutase activity level and the complement 3 and immunoglobulin M contents in the plasma. These results demonstrate that Oedocladium sp. and Tribonema sp. can be used as feed ingredients to improve flesh quality and increase the immunity of fish. [ABSTRACT FROM AUTHOR]