Grass Carp Ctenopharyngodon Idella Research Articles

Unveiling the emerging role of curcumin to alleviate ochratoxin A-induced muscle toxicity in grass carp (Ctenopharyngodon idella): in vitro and in vivo studies

BackgroundOchratoxin A (OTA), a globally abundant and extremely hazardous pollutant, is a significant source of contamination in aquafeeds and is responsible for severe food pollution. The developmental toxicity of OTA and the potential relieving strategy of natural products remain unclear. This study screened the substance curcumin (Cur), which had the best effect in alleviating OTA inhibition of myoblast proliferation, from 96 natural products and investigated its effect and mechanism in reducing OTA myotoxicity in vivo and in vitro.MethodsA total of 720 healthy juvenile grass carp, with an initial average body weight of 11.06 ± 0.05 g, were randomly assigned into 4 groups: the control group (without OTA and Cur), 1.2 mg/kg OTA group, 400 mg/kg Cur group, and 1.2 mg/kg OTA + 400 mg/kg Cur group. Each treatment consisted of 3 replicates (180 fish) for 60 d.ResultsFirstly, we cultured, purified, and identified myoblasts using the tissue block culture method. Through preliminary screening and re-screening of 96 substances, we examined cell proliferation-related indicators such as cell viability and ultimately found that Cur had the best effect. Secondly, Cur could alleviate OTA-inhibited myoblast differentiation and myofibrillar development-related proteins (MyoG and MYHC) in vivo and in vitro and improve the growth performance of grass carp. Then, Cur could also promote the expression of OTA-inhibited protein synthesis-related proteins (S6K1 and TOR), which was related to the activation of the AKT/TOR signaling pathway. Finally, Cur could downregulate the expression of OTA-enhanced protein degradation-related genes (murf1, foxo3a, and ub), which was related to the inhibition of the FoxO3a signaling pathway.ConclusionsIn summary, our data demonstrated the effectiveness of Cur in alleviating OTA myotoxicity in vivo and in vitro. This study confirms the rapidity, feasibility, and effectiveness of establishing a natural product screening method targeting myoblasts to alleviate fungal toxin toxicity.Graphical

The role of pantothenic acid in alleviating hypoxia-induced liver injury of sub-adult grass carp (Ctenopharyngodon idellus): Possible mechanisms and implication

In aquaculture, hypoxia poses a significant threat to fish growth and survival. Despite this, there is limited research on the impact of pantothenic acid (PA) in enhancing the anti-hypoxia stress capability of fish. The primary objective of this study was to explore the effects and potential mechanisms of PA in alleviating hypoxia-induced liver injury in sub-adult grass carp. To achieve this, six experimental diets containing varying levels of PA (0.08, 11.95, 24.95, 37.95, 50.95, and 63.95 mg/kg) were formulated and administered to grass carp (initial weight 696.22 ± 2.45 g) for 63 days. Following the dietary intervention, the fish were segregated into hypoxia and control groups and treated for 96 h. The findings revealed that optimal PA levels could enhance the growth performance of sub-adult grass carp and ameliorate the adverse impacts of hypoxia. First, optimal PA levels reduced serum levels of glutamate-oxaloacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), and lactate dehydrogenase (LDH), as well as mitigated hepatocyte vacuolization, improved liver and mitochondrial morphology, thereby alleviating hypoxia-induced liver injury. Furthermore, optimal PA levels were associated with increased contents of serum cortisol, glucose, liver glycogen, pyruvate, and the activities of Pantothenate kinase 2 (PanK2) and coenzyme A (CoA), while liver lactate content and LDH activity were reduced, indicating improvements in energy metabolism and PA utilization, potentially mediated by the down-regulation of hypoxia-inducible factor-1α (HIF-1α) mRNA level. Moreover, optimal PA levels decreased reactive oxygen species (ROS) and malondialdehyde (MDA) levels, enhanced liver antioxidant capacity, down-regulated autophagy-related gene mRNA levels, and up-regulated autophagy receptor protein 62 (p62) protein level, suggesting a reduction in oxidative damage and autophagy. Finally, a rise in levels of mitochondrial quality control-related mRNAs such as mitofusin 1/2 (MFN1/2), dynamin-related protein-1 (DRP-1), and nuclear respiratory factor 1/2 (Nrf-1/2) was observed, together with increment in the protein levels of PTEN induced putative kinase 1 (PINK1), BCL-2 interacting protein 3 (BNIP3) and FUN14 domain-containing protein 1 (FUNDC1). These alterations hinted at the role of PA in preserving mitochondrial homeostasis. In conclusion, PA exhibited a protective role against hypoxia-induced liver injury by enhancing liver energy metabolism, bolstering antioxidant defenses, suppressing autophagy, and maintaining mitochondrial homeostasis. Through an assessment of percentage weight gain (PWG) and liver ROS level, the requirements of PA for promoting growth and resilience to hypoxia-induced liver injury in sub-adult grass carp were determined to be 37.44 mg/kg and 42.57 mg/kg, respectively.

Selection of texture-associated biomarkers in chilled and iced grass carp (Ctenopharyngodon idella) fillets via DIA-based proteomics

Consumers care about the texture of fresh fish flesh, but a rapid quantitative analytical method for this has not been properly established. In this study, texture-associated biomarkers were selected by DIA-based proteomics for possible future application. Results indicated a significant decline in texture and moisture characteristics with extended storage under chilled and iced conditions, and flesh quality was categorized into three intervals. A total of 8 texture-associated biomarkers were identified in the chilled storage group, and 3 distinct ones in the iced storage group. Biomarkers were further refined based on their expression levels. Isobutyryl-CoA dehydrogenase, mitochondrial and [Phosphatase 2A protein]-leucine-carboxy methyltransferase were identified as effective texture-associated biomarkers for chilled fish, and Staphylococcal nuclease domain-containing protein 1 for iced fish. This study provided suitable proteins as indicators of fresh fish flesh texture, which could help establish a rapid and convenient texture testing method in future studies.

In vitro susceptibility of grass carp fish (Ctenopharyngodon idella) to oxidized myosin on structural change of protein secondary structure associated with reactive oxygen species (ROS) treatment

This study aimed to investigate the in vitro susceptibility of grass carp (Ctenopharyngodon idella) oxidized myosin, with the treatment of H2O2 levels being 0, 25, 50, and 100 μmol/L, respectively. The results showed that in vitro oxidation of myosin, reactive oxidative species promoted protein modifications that propagated the conformation changes on myosin secondary structure, leading to a significant increase (P < 0.05) in the protein carbonyl content in the high oxidation treatment, when compared to the low and medium treatments. The results of the Western blot analysis and sodium-polyacrylamide amide-dodecyl sulfate gel electrophoresis demonstrated that in vitro oxidation actively promoted the degradation of protein molecular weight and Desmin (53 kDa) deterioration in the sample with the highest concentration treatment of H2O2. Circular dichroism spectra showed a decrease in α-helix content from 70.1% to 29.8% and an increase in β-sheet percentage from 5.6% to 17.4%. Meanwhile, cysteine and methionine as the free amino acids were most susceptible to oxidative change due to their high sensitivity to the reaction of the sulfur group of amino acids. Protein degradation induced by oxidation resulted in significant changes to the protein secondary structure, as evidenced by the observation of oxidized myosin under different H2O2 levels.

Microelements, Fatty Acid Profile, and Selected Biomarkers in Grass Carp (Ctenopharyngodon idella) Muscle Tissue: Seasonal Variations and Health Risk Assessment

AbstractThe study assesses associations between microelement levels, fatty acid composition, and oxidative stress markers in grass carp muscle in the summer and autumn seasons. Additionally, various factors were considered, including the estimated daily intake (EDI), target hazard quotient (THQ), total THQ (TTHQ), and metal pollution index (MPI), to evaluate potential health risks for consumers. The microelements (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, Se, Sr, and Zn) were determined using inductively coupled plasma optical emission spectrometry (ICP-OES), and total mercury was determined using cold-vapor atomic absorption spectroscopy (CV-AAS). Fatty acid profiling was realized using gas chromatography (GC) detection with a flame ionization detector (FID). The overall tendency of microelement levels was as follows: Fe &gt; Zn &gt; Al &gt; Sr &gt; Ba &gt; Ni &gt; Se &gt; Cr&gt; Cu &gt; Mn &gt; Pb &gt; As &gt; Li &gt; Hg; &lt;LOQ (below limit of quantification): Cd, and Co. The correlation analysis between concentrations of trace elements (Al, Ba, Cr, Cu, Mn, Li, Sr, Zn, and Hg) and the fatty acids (C16:0, C16:1, C18:1n9c, C18:2n6c, C20:4n6c, EPA, and DHA), as well as between Al, Ba, Fe, or Hg and oxidative stress markers (superoxide dismutase—SOD, glutathione peroxidase—GPx, or total antioxidant status—TAS), revealed statistically significant interactions in different seasons. THQ values were lower than 1; TTHQ values ranged from 0.27 to 0.76. The main toxic elements forming TTHQ were Hg and Ni (49%). The calculated health risk assessment indices indicate a low concentration of observed elements and low risks associated with the consumption of grass carp muscle from the tested location, although concentrations and THQ of mercury and nickel may be of slight concern.

New insights into resveratrol attenuates hepatotoxicity in emamectin benzoate-exposed grass carp (Ctenopharyngodon idella) via NO system/NF-κB signaling pathway

Emamectin benzoate (EMB) is extensively used as a crop protection agent. Overuse of EMB poses a serious threat to the quality of water and non-target organisms in the environment. Resveratrol (RES) is a natural phytoalexin with the function of anti-oxidation and anti-inflammation. Nonetheless, it is unclear whether EMB affects the expression of cytokines and induces autophagy, apoptosis, and necroptosis of hepatocytes (L8824 cell) in grass carp (Ctenopharyngodon idella), and whether RES has an attenuate function in this process. Therefore, we established the L8824 cells model of EMB exposure and treated it with RES. The results showed that compared with the control (CON) group, EMB exposure significantly increased the nitric oxide (NO) content, inducible nitric oxide synthase (iNOS) activity, and the expression of iNOS and phosphorylated nuclear factor kappa B (p-NF-κB) (P < 0.05). In addition, compared with the CON group, the results of flow cytometry and dansylcadaverine (MDC) staining showed a significant increase in apoptosis and autophagy in the EMB-exposed group (P < 0.05) with the activation of the B-cell lymphoma-2 (Bcl-2)/Bcl-2 associated X (Bax)/cysteine-aspartic acid protease 3 (Caspase-3)/cysteine-aspartic acid protease 9 (Caspase-9) pathway and microtubule-associated protein light chain 3 (LC3)/sequestosome 1 (p62)/Beclin1 pathway. EMB exposure significantly increased the mRNA and protein expression of receptor-interacting protein 1 (RIPK1)/receptor-interacting protein 3 (RIPK3)/mixed the lineage kinase domain-like (MLKL) pathway (P < 0.05). Moreover, EMB exposure significantly increased the expression of genes related to immunity (immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin D (IgD), and antimicrobial peptide-related genes expression including β-defensin and hepcidin) (P < 0.05). The addition of RES significantly diminished autophagy, apoptosis, necroptosis, and immunity-related gene expression by inhibiting iNOS activity, NO content, and the protein expression of iNOS and p-NF-κB. In conclusion, RES attenuated autophagy, apoptosis, and necroptosis in EMB-exposed L8824 cells via suppression of the NO system/NF-κB signaling pathway.

Identification of novel SNPs and candidate genes significantly affecting growth in grass carp (Ctenopharyngodon idella) through GWAS analysis

Grass carp (Ctenopharyngodon idella) is one of the most important cultivated fish species in the global freshwater aquaculture with fast growth, low cost of production and delicious meat. A breeding program to improve economically important growth traits in grass carp would benefit from effective molecular markers. Although a genetic linkage map of grass carp has been constructed, and quantitative trait loci (QTL) mapping and a genome-wide association study (GWAS) have been conducted, the effective number of SNP markers and genes currently available for breeding is still very limited. In this study, we conducted a GWAS based on re-sequencing of individuals to identify genomic regions and candidate genes potentially associated with various growth traits of grass carp, including body weight (BW), body length (BL) and body height (BH). A total of 4,854,366 high-quality SNPs were identified and located on 24 chromosomes. Among them, 31 SNPs were identified as being associated with growth traits, including 8 SNPs on chromosomes 1, 2, 10, 13, 14, 17 and 22 associated with BW, 21 SNPs on chromosomes 2, 4, 5, 8, 10, 13, 14, 15, 17, 23 and 24 correlated with BL, and 18 SNPs on chromosomes 2, 9, 10, 13, 14, 17, 23 and 24 related to BH. In addition, 13 of these SNPs were simultaneously associated with two or three growth traits. Within a 48 kb range upstream and downstream of these significant SNPs, 120 candidate genes were identified to be associated with the QTLs. Most of these genes were related to growth and development, fat metabolism, bone mineralization and differentiation, vascular development, or feeding regulation. Notably, the genes pwp1, cers5, chrebp, lsr, ctnnbip1, smoc2, ano6 and cckrb were specifically associated with growth, fat, bone formation and feeding. Our findings would provide a foundation for molecular marker-assisted selection, genomic selection, and functional analysis of growth traits in grass carp.

Identification and functional analyses of CD4-1+ cells in grass carp (Ctenopharyngodon idella)

In mammals, CD4 is found to be expressed on T cells and innate immune cells, however, teleost cells bearing CD4 have not been well identified and characterized. In this study, we identified two different CD4-1+ cell subsets in grass carp (Ctenopharyngodon idella): CD4-1+ lymphocytes (Lym) and CD4-1+ myeloid cells (Mye), both of which had the highest proportions in the head kidney. The mRNA expression analysis showed that CD4-1, CD4-2, TCRβ, CD3γ/δ, and LCK1 are highly expressed in CD4-1+ Lym and also expressed in CD4-1+ Mye. Furthermore, we found that CD4-1+ Lym have a Lym morphology and highly express T-cell cytokines, suggesting that they are CD4+ T cells equivalent to mammalian Th cells. On the other hand, CD4-1+ Mye were found to have a morphology of macrophages and highly express MCSFR, indicating that they are macrophages. In addition, functional analysis revealed that CD4-1+ Mye possess phagocytic ability and great antigen-processing ability. Taken together, our study sheds further light on the composition and function of CD4+ cells in teleost fish.

Ecological inferences on invasive carp survival using hydrodynamics and egg drift models

Bighead carp (Hypophthalmichthys nobilis), silver carp (H. molitrix), black carp (Mylopharyngodon piceus), and grass carp (Ctenopharyngodon idella), are invasive species in North America. However, they hold significant economic importance as food sources in China. The drifting stage of carp eggs has received great attention because egg survival rate is strongly affected by river hydrodynamics. In this study, we explored egg-drift dynamics using computational fluid dynamics (CFD) models to infer potential egg settling zones based on mechanistic criteria from simulated turbulence in the Lower Missouri River. Using an 8-km reach, we simulated flow characteristics with four different discharges, representing 45–3% daily flow exceedance. The CFD results elucidate the highly heterogeneous spatial distribution of flow velocity, flow depth, turbulence kinetic energy (TKE), and the dissipation rate of TKE. The river hydrodynamics were used to determine potential egg settling zones using criteria based on shear velocity, vertical turbulence intensity, and Rouse number. Importantly, we examined the difference between hydrodynamic-inferred settling zones and settling zones predicted using an egg-drift transport model. The results indicate that hydrodynamic inference is useful in determining the ‘potential’ of egg settling, however, egg drifting paths should be taken into account to improve prediction. Our simulation results also indicate that the river turbulence does not surpass the laboratory-identified threshold to pose a threat to carp eggs.

Isalo scorpion cytotoxic peptide‐strengthened immune function through the JAKs/STATs signaling pathway of the immune organ of grass carp (Ctenopharyngodon idella) challenged with Aeromonas hydrophila

AbstractTo investigate the impact of Isalo scorpion cytotoxic peptide (IsCT) on the immune function of immune organ (head kidney, spleen, and skin) of grass carp (Ctenopharyngodon idella), 540 fish (136.88 ± 0.72 g) were supplied with a different amount of IsCT (0, 0.6, 1.2, 1.8, 2.4, and 3.0 mg/kg diet) through a period of 60 days. Afterward, 24 fish were randomly selected from each group and were inoculated with Aeromonas hydrophila for a period of 6 days. Our findings suggested that appropriate IsCT complementation: (1) attenuated skin morbidity and histopathological structural changes in the head kidney and spleen (p &lt; 0.05), which ensured the structural integrity of the immune organs; (2) increased the activity and expression of immune substances (p &lt; 0.05), which in turn increased the function of the immune organs, promoting immune responses; (3) through the regulation of the Janus kinase/signal transducers and activators of transcription (JAKs/STATs) signaling pathway, the mRNA expression of anti‐inflammatory cytokines increased and the mRNA expression of pro‐inflammatory cytokines decreased, which in turn increased the function of the immune organs, reducing the inflammatory response (p &lt; 0.05). However, the addition of IsCT did not affect the expression of IL‐12p35, STAT2, and STAT3a in the immune organ. Ultimately, this study provided evidence that IsCT enhanced immune function via the JAKs/STATs signaling pathway in the immune organ in grass carp after challenged with Aeromonas hydrophila.

Single and combined effects of high-fat diet and ammonia nitrogen on oxidative stress, lipid accumulation and inflammation in liver of grass carp Ctenopharyngodon idella

The current study aims to investigate the role of high-fat diet (HFD) and ammonia nitrogen (AN) in the fatty liver disease progression in farmed fish. In the present study, grass carp were fed the normal fat diet or HFD for 4 weeks to set up the Control group, HFD group, AN group and HFD + AN group. In the AN group and HFD + AN group, grass carp were exposed to 0.52 mg/L NH3-N for the last week. The results show that HFD feeding had no effect on the growth of grass carp but AN stress significantly inhibited it. Further, the HFD feeding and AN challenge both significantly increased the level of alanine aminotransferase (ALT) and reduced the total antioxidant capacity (T-AOC) significantly. Moreover, a further aggravated liver injury appeared in HFD-fed grass carp after AN challenge, as evidenced by the significant increasing of the level of ALT, AST and malondialdehyde (MDA) and marked reducing of glutathione (GSH) and T-AOC. Moreover, the results of Oil Red O and TG contents in liver all indicate that HFD and AN challenge both promoted the lipid accumulation in grass carp liver. Corresponding to this, the results of genes and protein related to lipid metabolism reveal that AN challenge dramatically inhibited lipid hydrolysis, lipophagy and fatty acid oxidation in HFD-fed grass carp liver but the single HFD feeding or AN challenge did not have this effect. Moreover, the single HFD feeding and AN challenge both promoted fatty acid transport to the liver and lipid synthesis in grass carp liver. In summary, the HFD feeding and AN challenge both can disturb the lipid metabolism in grass carp liver. In parallel, the results of expression levels of genes and protein related to inflammation indicate that the single HFD feeding might not significantly contribute to the inflammation in grass carp liver, but the single AN challenge apparently promoted the inflammatory process. Most importantly, inflammatory progression in liver was further aggravated in the HFD-fed grass carp after AN challenge compared to grass carp with only AN stress, mostly evidenced by the increased levels of inflammatory factors (il1β, il2, TNF-α, etc.). In summary, AN challenge significantly promoted the lipid accumulation and inflammatory process in the liver of HFD-fed grass carp, which might have further aggravated liver injury.

Identification of hub genes in meat quality of grass carp (Ctenopharyngodon idellus) fed with faba bean by muscle tissue transcriptomic analysis

Crisp grass carp is a type of grass carp (Ctenopharyngodon idella) that has been fed faba beans. Flesh quality and expression of muscle quality-related genes in muscle of grass carp were evaluated. Compared with ordinary grass carp, 1901 differentially expressed genes (DEGs) were up-regulated and 1628 DEGs were down-regulated in crisp grass carp. The GO analysis results showed that the DEGs were enriched in ribosomes and proteins. Kyoto Encyclopaedia of genes and genomes (KEGG) pathway analysis results showed that amino acid metabolism was closely related to meat quality. COX3, ACADS, ACAT1, ECHS1, EHHADH, HADHAA, HADH, HMGCL, MCCC1 and MCCC2 were the top 10 hub genes most closely associated with other nodes and showed a strong positive correlation. Hardness was positively correlated with the COX3, ECHS1, ACADS, ACAT1, HADHA, HADH, HMGCL and MCCC1. These results have been demonstrated to play important roles in clarifying the molecular mechanism of muscle firmness increase in crisp grass carp.

Comparative Analysis of Nutritional Quality, Serum Biochemical Indices, and Visceral Peritoneum of Grass Carp (Ctenopharyngodon idellus) Fed with Two Distinct Aquaculture Systems.

This study scrutinized the nutritional quality and serum biochemical indices of grass carp (Ctenopharyngodon idellus) cultivated in traditional pond intercropping (TPI) and in-pond raceway system (IPRS) aquaculture setups. The findings showed that the TPI group exhibited a superior water-holding capacity, while the IPRS showcased heightened crude lipid content and levels of textural properties such as springiness. Moreover, significant differences emerged in the fatty acid profiles, with the TPI group manifesting higher total polyunsaturated fatty acids (ΣPUFAs), EPA, DHA, and Σn-3, while the IPRS group exhibited elevated total saturated fatty acids (ΣSFAs). In terms of amino acids, valine and histidine levels were notably higher in the IPRS group, whereas lysine levels were reduced. Volatile compound analysis revealed significant variations, with the IPRS group containing more volatile substances with a better aroma, resulting in a better odor. The IPRS group performed better in serum biochemistry analysis. Additionally, grass carp in the IPRS group displayed an improved structure and greater coverage area of the visceral peritoneum, appearing lighter in color compared to the TPI group. TPI mainly influences nutritional elements; IPRSs primarily affect muscle texture, serum biochemistry, and overall health. This study aims to fill the gap in quality comparison research and provide an important scientific basis.

Aflatoxin B1 inhibited the development of primary myoblasts of grass carp (Ctenopharyngodon idella) by degrading extracellular matrix

According to the International Agency for Research on Cancer (IARC), aflatoxin B1 (AFB1) has been recognized as a major contaminant in food and animal feed and which is a common mycotoxin with high toxicity. Previous research has found that AFB1 inhibited zebrafish muscle development. However, the potential mechanism of AFB1 on fish muscle development is unknown, so it is necessary to conduct further investigation. In the present research, the primary myoblast of grass carp was used as a model, we treated myoblasts with AFB1 for 24 h. Our results found that 5 μM AFB1 significantly inhibited cell proliferation and migration (P < 0.05), and 10 μM AFB1 promoted lactate dehydrogenase (LDH) release (P < 0.05). Reactive oxygen species (ROS), protein carbonyl (PC) and malondialdehyde (MDA) levels were increased in 15, 5 and 10 μM AFB1 (P < 0.05), respectively. Catalase (CAT), glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activities were decreased in 10, 10 and 15 μM AFB1 (P < 0.05), respectively. Furthermore, 15 μM AFB1 induced oxidative damage by Nrf2 pathway, also induced apoptosis in primary myoblast of grass carp. Meanwhile, 15 μM AFB1 decreased MyoD gene and protein expression (P < 0.05). Importantly, 15 μM AFB1 decreased the protein expression of collagen Ⅰ and fibronectin (P < 0.05), and increased the protein levels of urokinase plasminogen activator (uPA), matrix metalloproteinase 9 (MMP-9), matrix metalloproteinase 2 (MMP-2), and p38 mitogen-activated protein kinase (p38MAPK) (P < 0.05). As a result, our findings suggested that AFB1 damaged the cell morphology, induced oxidative damage and apoptosis, degraded ECM components, in turn inhibiting myoblast development by activating the p38MAPK/urokinase-type plasminogen activator (uPA)/matrix metalloproteinase (MMPs)/extracellular matrix (ECM) signaling pathway.

Introducing Copi as a Positive Path Toward Combatting Invasive Carps in North America

A group of loosely related, large‐bodied fishes collectively called carps have had a complex relationship with North Americans. Despite lessons learned about invasive Common Carp Cyprinus carpio in the early 1900s, Bighead Carp Hypophthalmichthys nobilis, Black Carp Mylopharyngodon piceus, Grass Carp Ctenopharyngodon idella, and Silver Carp H. molitrix were introduced to the United States more than 50 years ago and are expanding throughout the Mississippi River basin. Increased economic value in the North American seafood market could aid management. Complete eradication through harvest is unlikely, but controlling densities and containing dispersal may be possible. Improving perceptions of nutrition, palatability, and safety of wild‐caught carps should increase consumer demand. A branding and marketing effort launched in June 2022 renamed the foodstuff produced from the four species as the trademarked brand Copi. The “Choose Copi: Eat Well. Do Good.” campaign allows consumers to know that these fishes are an environmentally sound and responsible alternative to other seafood choices. The Copi brand has gained interest nationwide, with food processors and distributors engaged, although the contribution of Copi to harvest removal from rivers and resulting population dynamics is yet to be quantified. Developing a regional fishing industry for Copi, while also aiding fisheries and aquaculture for native species, remains an economic and logistical challenge within the vast river network.

Taurine prevented the decline of fillet quality and muscle antioxidant capacity in on-growing grass carp (Ctenopharyngodon idella) fed non-fishmeal diet

Taurine is abundantly present in fishmeal, while plant protein sources typically contain minimal to no taurine. This disparity in taurine content may explain variations in fish quality traits caused by the dietary substitution of fishmeal with plant protein sources. This research explored whether taurine supplementation to non-fishmeal (NFM) diet could improve fillet quality and muscle antioxidant capacity in grass carp. A total of 540 fish (255.74 ± 0.65 g) were distributed among six groups. One of them was provided with a fishmeal (FM) diet, while the remaining five groups received NFM diets, formulated with incremental concentrations of crystalline taurine (0, 0.5, 1.0, 1.5, 2.0 g/kg) for 60 days. Our data showed that, in comparison with the un-supplemented group, the optimal taurine supplementation to NFM diet yielded the following findings: (1) increased fillet nutritional values by improving crude protein content, free amino acid and fatty acid compositions; (2) improved fillet physicochemical properties by improving water holding capacity (WHC), tenderness, and preventing pH decline; (3) enhanced antioxidant enzymes activities and gene expressions through nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway. Additionally, this optimal NFM diet showed to be competitive with FM diet in terms of fillet quality. According to quadratic regression curves of ROS production and polyunsaturated fatty acids (PUFA) content, the optimal taurine supplementation levels in NFM diet for on-growing grass carp were 1.12 and 1.18 g/kg diet, respectively.

Cryoprotective effects and mechanisms of soybean oligosaccharides on the grass carp (Ctenopharyngodon idellus) surimi during frozen storage.

Conventional cryoprotectant mixtures (sucrose and sorbitol) impart excessive sweetness and calories to surimi. Therefore, there is a need to explore alternative cryoprotectants with low sweetness and low-calorie content. The cryoprotective effects and possible mechanisms of soybean oligosaccharides (SBOS) on the frozen stability of grass carp (Ctenopharyngodon idellus) surimi were investigated during 120 days of frozen storage in a comparison with commercial cryoprotectants (4% sucrose and 4% sorbitol, w/w). SBOS at 6-8% (w/w) and commercial cryoprotectants could restrain water mobility and reduce thawing loss of frozen surimi by increasing non-freezable water content. SBOS could maintain the structural stability of proteins by preventing sulfhydryl groups from being rapidly oxidized to disulfide bonds, retarding the reduction of the solubility, Ca2+-ATPase activity and α-helix content of myofibrillar proteins (MP), as well as hindering the increasing surface hydrophobicity of MP of surimi during 120 days of frozen storage. The introduction of SBOS increased the gel strength and water-holding capacity of frozen-stored surimi. Compared with commercial cryoprotectants, 8% SBOS was more effective in stabilizing protein structure, whereas it was slightly less effective with respect to ice-forming inhibition. The results obtained in the present study suggest that 8% SBOS could be potentially developed as a new cryoprotectant for surimi as a result of its ice-forming inhibition abilities and protein structure stability. © 2024 Society of Chemical Industry.

Reproduction of grass carp (Ctenopharyngodon idella) in the Maumee River, Ohio: Part 2—Optimal river conditions for egg and larval drift

This study uses a one-dimensional steady-state hydraulic model and the Fluvial Egg Drift Simulator (FluEgg) to model the drift and dispersion of grass carp eggs and larvae in the Maumee River, Ohio, for 180 scenarios representing different combinations of 10 river flows, 6 water temperatures, and 3 spawning locations. The FluEgg simulations were used to quantify in-river suspended hatching rates (the percentage of eggs that hatch within the river and in suspension) and in-river larval retention rates (the percentage of larvae that reach the gas bladder inflation stage within the river after hatching in suspension), and identify which scenarios produce the highest likelihood of recruitment. The simulations indicate that at low flows, in-river suspended hatching and larval retention rates in the Maumee River are limited by the capacity of the flow to keep fertilized eggs in suspension, whereas at high flows, the limiting factor is the distance available for the eggs/larvae to drift in the river. A wide range of scenarios result in eggs hatching within the river, but all larvae drift into Maumee Bay prior to the gas bladder inflation stage when flows exceed the mean annual flow. The simulations were assessed in the context of the hydraulic conditions that trigger spawning and maximize egg fertilization and the nursery habitat requirements for larval grass carp. The results indicate that the Maumee River, although suitable for grass carp spawning, may not be an ideal setting for recruitment unless Maumee Bay provides adequate nursery habitat for larvae.

Dietary copper improves intestinal structural integrity in juvenile grass carp (Ctenopharyngodon idella) probably related to its increased intestinal antioxidant capacity and apical junction complex

This research evaluated the effects of copper (Cu) on intestinal antioxidant capacity and apical junctional complex (AJC) in juvenile grass carp. A total of 1080 healthy juvenile grass carp (11.16 ± 0.01 g) were fed six diets including different dosages of Cu, namely 0, 2, 4, 6, 8 (Cu citrate [CuCit] as Cu source) and 3 mg/kg (CuSO4·5H2O as Cu source), lasting for 9 weeks. The findings revealed that dietary optimal Cu supplementation (2.2 to 4.1 mg/kg) promoted intestinal growth, including intestinal length, intestinal length index, intestinal weight, and intestinal somatic index (P < 0.05). Furthermore, optimal Cu boosted the intestinal mucosal barrier in juvenile grass carp. On the one hand, optimal Cu reduced diamine oxidase and D-lactate levels in serum (P < 0.05), reduced levels of the oxidative damage indicators malondialdehyde, reactive oxygen species (ROS), protein carbonyl, and also elevated superoxide dismutase and catalase mRNA levels (P < 0.05), thus boosting intestinal antioxidant capacity, in which the binding protein Keap1a/1b/Nrf2 signaling pathway might be involved. Optimal Cu had no impact on glutathione peroxidase 1b (GPx1b) gene expression (P > 0.05). On the other hand, optimal Cu increased intestinal tight junction (TJ) proteins (except for claudin 15b) and adherens junction (AJ) proteins (E-cadherin, α-catenin, β-catenin, nectin and afadin) mRNA levels (P < 0.05), which could be connected to the signaling pathway formed by the Ras homolog gene family, member A (RhoA), Rho-associated protein kinase (ROCK), and myosin light chain kinase (MLCK). Finally, based on serum indicator D-lactate and intestinal oxidative damage index (ROS), Cu requirement (CuCit as Cu source) for juvenile grass carp from initial weight to final weight (from 11 to 173 g) was determined to be 4.14 and 4.12 mg/kg diet, respectively. This work may provide a theoretical foundation for identifying putative Cu regulation pathways on fish intestinal health.

Investigations on growth performance of grass carp Ctenopharyngodon idella (Cuvier and Valenciennes,1844) under forage crops and aquatic macrophyte feeding regimes

The objective of the study was to assess the growth, survival, and production performanceof grass carp Ctenopharyngodon Idella (Cuvier and Valenciennes, 1844) under differentfeeding regimes of forage crops and aquatic macrophytes. In the present experiment, 650fingerlings (average length, 11.13±0.29 cm and average weight, 13.89±0.81 g) of grass carpwere stocked separately in two earthen ponds (40 x 25 x 2.0 m). Fishes in pond one (T1)were fed with forage crops, chopped Napier grass (Pennisetum purpureum) from June toNovember 2017 and chopped Berseem (Trifolium alexandrinum) from January to May 2018.Similarly, fishes in pond 2 (T2) were fed with Azolla (Azolla pinnata) and Lemna (Lemna minor)during the period June to November 2017 and January to May 2018, respectively. Lineartrend analysis for the length of grass carp showed a significant (p&lt;0.05) increase in size inboth treatments (T1 and T2) and r2 was found to be 0.94 and 0.95, while increasing trend ofweight of grass carp showed significantly (p&lt;0.05) high r2 for T1 (0.88) and T2 (0.84). It isobserved that the application of forage (T1) and aquatic macrophytes (T2) had no significant(p&gt;0.05) effect on the water quality parameters of each pond. The overall specific growthrate, average daily weight gain and feed conversion ratio of grass carp were significantly(p&lt;0.05) higher in T1 compared to T2, while the survival rate was significantly (p&lt;0.05) high in T2. Keywords:Earthen pond, Feed conversion ratio, Macrophytes,Specific growth rate, Survival