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Selenium (Se), a trace element, is vital for the maintenance of cellular redox balance, thyroid hormone metabolism, inflammation, and immunity. Aeromonas hydrophila (A. hydrophila) is a common Gram-negative conditional pathogenic bacterium in fish culture, posing a serious threat to intensive aquaculture. Our study investigated the influence of dietary Se on the intestinal immune function of grass carp (Ctenopharyngodon idella) and the related regulatory mechanisms. The 2160 healthy juvenile grass carp (9.76 ± 0.005 g) were randomly assigned to 6 test groups of 6 replicates each, and fed graded selenomethionine (0.05, 0.20, 0.40, 0.61, 0.77, 0.98 mg Se/kg diet) for 70 days and then injected with A. hydrophila for a 6-day attack test. The results indicated that appropriate Se levels (0.40 mg/kg diet) alleviated intestinal damage caused by A. hydrophila and increased intestinal immune substances C3 and C4 levels as well as the activity of acid phosphatase (ACP) and lysozyme (LZ) (P > 0.05). Appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) decreased intestinal pro-inflammatory cytokines (IFN-γ2, IL-6, IL-12p35, IL-17 A F and IL-17D) mRNA levels (P > 0.05) and increased intestinal anti-inflammatory factors (TGF-ß1, IL-4/13A, IL-4/13B, IL-10 and IL-22) mRNA levels (P > 0.05) in juvenile grass carp. Further studies revealed that Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal endoplasmic reticulum stress (ERS)-related signaling pathway. Furthermore, we found that appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal autophagy in juvenile grass carp, which may be related to ULK1, Beclin 1, ATG5, ATG12, LC3, and P62. In conclusion, appropriate levels of Se can alleviate intestinal inflammation and inhibit ERS and autophagy in juvenile grass carp. A quadratic regression analysis of intestinal ACP and LZ also indicated that the Se requirements of juvenile grass carp were 0.59 and 0.51 mg/kg, respectively.
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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 mg/kg (Cu citrate [CuCit] as Cu source) and 3 mg/kg (CuSO4·5H2O as Cu source). The trial lasted 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, superoxide dismutase (P < 0.05), and catalase mRNA levels were elevated (P < 0.05), thus boosting intestinal antioxidant capacity, 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, ß-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 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.
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In nature, aflatoxins, especially aflatoxin B1 (AFB1), are the common mycotoxins, which cause serious health problems for humans and animals. This paper aimed to study the effects of AFB1 on flesh flavor and muscle development of grass carp (Ctenopharyngodon idella) and its mechanism. There were 1440 individual fish in total, with 6 treatments and each treatment replicated 3 times. The 6 treatments were fed a control diet with different doses of AFB1 (0.04, 29.48, 58.66, 85.94, 110.43 and 146.92 µg/kg diet) for 60 d. AFB1 increased myofiber diameter, as well as decreased myofiber density of grass carp muscle (P < 0.05). The contents of free amino acid decreased gradually (P < 0.05) as dietary AFB1 increased in the muscle of grass carp. The levels of reactive oxygen species, malonaldehyde and protein carbonyl (PC) were increased (P < 0.05) with the dietary AFB1 increased. The levels of antioxidant enzyme (glutathione peroxidase, glutathione, glutathione reductase, total antioxidant capacity, anti-superoxide anion, and anti-hydroxyl radical) were decreased (P < 0.05) with the dietary AFB1 increased. In addition, dietary AFB1 decreased the content of collagen, and downregulated the mRNA and protein levels of transforming growth factor-ß (TGF-ß)/Smads signaling pathway in grass carp muscle (P < 0.05). The mRNA and protein levels of myogenic regulatory factors were downregulated in grass carp muscle (P < 0.05). Furthermore, the activities of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) were increased (P < 0.05), and the protein levels of phosphorylate-38 mitogen-activated protein kinase (p-p38MAPK), phosphorylate-c-Jun N-terminal kinase, urokinase-type plasminogen activator (uPA), MMP-2 and MMP-9 were upregulated (P < 0.05), but collagen â , laminin ß1 and fibronectin were downregulated (P < 0.05) with the dietary AFB1 increased in the muscle of grass carp. Based on the results of this study, we can draw the following conclusion: dietary AFB1 might damage flesh flavor and inhibit the muscle development through MAPK/uPA/MMP/extracellular matrix (ECM) signaling pathway in grass carp. Moreover, the recommended safe limit of AFB1 in feed is no more than 26.77 µg/kg diet according to the PC levels in grass carp muscle.
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Leucine is an essential amino acid for fish. The ability of leucine to resist stress in fish has not been reported. Nitrite is a common pollutant in the aquatic environment. Therefore, we investigated the effects of dietary leucine on growth performance and nitrite-induced liver damage, mitochondrial dysfunction, autophagy, and apoptosis for sub-adult grass carp. A total of 450 grass carp (615.91 ± 1.15 g) were selected and randomly placed into 18 net cages. The leucine contents of the six diets were 2.91, 5.90, 8.92, 11.91, 14.93, and 17.92 g/kg, respectively. After a 9-week feeding trial, the nitrite exposure experiment was set up for 96 h. These results indicated that dietary leucine significantly promoted FW, WG, PWG, and SGR of sub-adult grass carp (P < 0.05). Appropriate levels of dietary leucine (11.91-17.92 g/kg) decreased the activities of serum parameters (glucose, cortisol, and methemoglobin contents, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactate dehydrogenase), the contents of reactive oxygen species (ROS), nitric oxide (NO) and peroxynitrite (ONOO-). In addition, appropriate levels of dietary leucine (11.91-17.92 g/kg) increased the mRNA levels of mitochondrial biogenesis genes (PGC-1α, Nrf1/2, TFAM), fusion-related genes (Opa1, Mfn1/2) (P < 0.05), and decreased the mRNA levels of caspase 3, caspase 8, caspase 9, fission-related gene (Drp1), mitophagy-related genes (Pink1, Parkin) and autophagy-related genes (Beclin1, Ulk1, Atg5, Atg7, Atg12) (P < 0.05). Appropriate levels of dietary leucine (8.92-17.92 g/kg) also increased the protein levels of AMP-activated protein kinase (AMPK), prostacyclin (p62) and decreased the protein levels of protein light chain 3 (LC3), E3 ubiquitin ligase (Parkin), and Cytochrome c (Cytc). Appropriate levels of leucine (8.92-17.92 g/kg) could promote growth performance and alleviate nitrite-induced mitochondrial dysfunction, autophagy, apoptosis for sub-adult grass carp. Based on quadratic regression analysis of PWG and serum GPT activity, dietary leucine requirements of sub-adult grass carp were recommended to be 12.47 g/kg diet and 12.55 g/kg diet, respectively.
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Alimentación Animal , Carpas , Dieta , Suplementos Dietéticos , Leucina , Nitritos , Animales , Alimentación Animal/análisis , Leucina/administración & dosificación , Leucina/farmacología , Dieta/veterinaria , Suplementos Dietéticos/análisis , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Distribución Aleatoria , Hígado/efectos de los fármacos , Hígado/metabolismo , Enfermedades de los Peces/inducido químicamente , Enfermedades de los Peces/prevención & control , Contaminantes Químicos del Agua/efectos adversos , Apoptosis/efectos de los fármacos , Relación Dosis-Respuesta a DrogaRESUMEN
Muscle is the main edible part of bony fish. The purpose of this study was to investigate the influences of phenylalanine (Phe) on muscle quality, amino acid composition, fatty acid composition, glucose metabolism, and protein deposition in adult grass carp. The diets at 2.30, 4.63, 7.51, 10.97, 13.53, and 17.07 g/kg Phe levels were fed for 9 weeks. The results manifested that Phe (10.97-13.53 g/kg) increased the pH of the fillets and decreased muscle cooking loss and lactic acid content; Phe (7.51-17.07 g/kg) improved the composition of the fillets in terms of flavor (free) amino acids, bound amino acids (especially EAA), and fatty acids (especially EPA and DHA); Phe (7.51-13.53 g/kg) increased muscle glycogen content (possibly related to the AMPK signaling pathway) and muscle protein deposition (possibly related to IGF-1/4EBP1/TOR and AKT/FOXOs signaling pathways). In conclusion, a diet with appropriate Phe levels could improve fillet quality.
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Energy metabolism exerts profound impacts on flesh quality. Niacin can be transformed into nicotinamide adenine dinucleotide (NAD), which is indispensable to energy metabolism. To investigate whether niacin deficiency could affect energy metabolism and flesh quality, six diets with graded levels of 0.49, 9.30, 21.30, 33.30, 45.30 and 57.30 mg/kg niacin were fed to grass carp (Ctenopharyngodon idella) for 63 days. The results showed that niacin deficiency declined flesh quality by changing amino acid and fatty acid profiles, decreasing shear force, increasing cooking loss and accelerating pH decline. The accelerated pH decline might be associated with enhanced glycolysis as evident by increased hexokinase (HK), pyruvate kinase (PK) and lactic dehydrogenase (LDH) activities, and mitochondrial dysfunction as evident by destroyed mitochondrial morphology, impaired respiratory chain complex I and antioxidant ability. Based on PWG and cooking loss, the niacin requirements for sub-adult grass carp were 31.95 mg/kg and 29.66 mg/kg diet, respectively.
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Carpas , Glucólisis , Mitocondrias , Niacina , Animales , Carpas/metabolismo , Niacina/metabolismo , Niacina/deficiencia , Mitocondrias/metabolismo , Alimentación Animal/análisis , Homeostasis , Culinaria , Carne/análisisRESUMEN
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 24â¯h. Our results found that 5⯵M AFB1 significantly inhibited cell proliferation and migration (P < 0.05), and 10⯵M 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⯵M AFB1 (P < 0.05), respectively. Catalase (CAT), glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activities were decreased in 10, 10 and 15⯵M AFB1 (P < 0.05), respectively. Furthermore, 15⯵M AFB1 induced oxidative damage by Nrf2 pathway, also induced apoptosis in primary myoblast of grass carp. Meanwhile, 15⯵M AFB1 decreased MyoD gene and protein expression (P < 0.05). Importantly, 15⯵M AFB1 decreased the protein expression of collagen â 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.
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Aflatoxina B1 , Carpas , Proliferación Celular , Matriz Extracelular , Mioblastos , Especies Reactivas de Oxígeno , Animales , Aflatoxina B1/toxicidad , Mioblastos/efectos de los fármacos , Matriz Extracelular/efectos de los fármacos , Matriz Extracelular/metabolismo , Proliferación Celular/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Estrés Oxidativo/efectos de los fármacos , Movimiento Celular/efectos de los fármacosRESUMEN
Hypoxia in water environment is one of the important problems faced by intensive aquaculture. Under hypoxia stress, the effects of dietary thiamine were investigated on grass carp gill tissue damage and their mechanisms. Six thiamine diets with different thiamine levels (0.22, 0.43, 0.73, 1.03, 1.33 and 1.63 mg/kg) were fed grass carp (Ctenopharyngodon idella) for 63 days. Then, 96-hour hypoxia stress test was conducted. This study described that thiamine enhanced the growth performance of adult grass carp and ameliorated nutritional status of thiamine (pyruvic acid, glucose, lactic acid and transketolase). Additionally, thiamine alleviated the deterioration of blood parameters [glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), glucose, cortisol, lactic dehydrogenase (LDH), erythrocyte fragility, and red blood cell count (RBC count)] caused by hypoxia stress, and reduced reactive oxygen species (ROS) content and oxidative damage to the gills. In addition, thiamine alleviated endoplasmic reticulum stress in the gills, which may be related to its inhibition of RNA-dependent protein kinase-like ER kinase (PERK)/eukaryotic translation initiation factor-2α (eIF2α)/activating transcription factor4 (ATF4), inositol-requiring enzyme 1 (IRE1)/X-Box binding protein 1 (XBP1) and activating transcription factor 6 (ATF6) pathways. Furthermore, thiamine maintaining mitochondrial dynamics balance was probably related to promoting mitochondrial fusion and inhibiting mitochondrial fission, and inhibiting mitophagy may involve PTEN induced putative kinase 1 (PINK1)/Parkin-dependent pathway and hypoxia-inducible factor (HIF)-Bcl-2 adenovirus E1B 19 kDa interacting protein 3 (BNIP3) pathway. In summary, thiamine alleviated hypoxia stress in fish gills, which may be related to reducing endoplasmic reticulum stress, regulating mitochondrial dynamics balance and reducing mitophagy. The thiamine requirement for optimum growth [percent weight gain (PWG)] of adult grass carp was estimated to be 0.81 mg/kg diet. Based on the index of anti-hypoxia stress (ROS content in gill), the thiamine requirement for adult grass carp was estimated to be 1.32 mg/kg diet.
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Carpas , Branquias , Animales , Branquias/metabolismo , Carpas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Proteínas de Peces/metabolismo , Inmunidad Innata , Dieta/veterinaria , Homeostasis , Glucosa/metabolismo , Alimentación Animal/análisisRESUMEN
Lactobacillus rhamnosus is a probiotic, which not only promotes the growth of animals, but also has anti-inflammatory effects. However, the mechanism by which Lactobacillus rhamnosus regulates intestinal immunity is not well comprehended. Hence, the study aimed to research how Lactobacillus rhamnosus affects the intestinal immunity using juvenile grass carp (Ctenopharyngodon idella) as a model. We selected 1800 juvenile grass carp for testing. They were divided into six treatments and fed with six gradients of Lactobacillus rhamnosus GCC-3 (0.0, 0.5, 1.0, 1.5, 2.0, 2.5 g/kg) for 70 days. Enteritis was subsequently induced with dextroside sodium sulfate. Results indicated that dietary Lactobacillus rhamnosus GCC-3 addition improved growth performance. Meanwhile, appropriate levels of Lactobacillus rhamnosus GCC-3 alleviated excessive inflammatory response by down-regulating the expression of TLR4 and NOD receptors, up-regulating the expression of TOR, and then down-regulating the expression of NF-κB. Additionally, appropriate Lactobacillus rhamnosus GCC-3 improved intestinal immunity by reducing pyroptosis triggered by NLRP3 inflammasome and mediated by GSDME. Furthermore, 16 S rRNA sequencing showing appropriate levels of Lactobacillus rhamnosus GCC-3 increased Lactobacillus and Bifidobacterium abundance and decreased Aeromonas abundance. These results suggest that Lactobacillus rhamnosus GCC-3 can alleviate intestinal inflammation through down-regulating NF-κB and up-regulating TOR signaling pathways, as well as by inhibiting pyroptosis.
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Carpas , Enfermedades de los Peces , Lacticaseibacillus rhamnosus , Animales , FN-kappa B/metabolismo , Suplementos Dietéticos , Inmunidad Innata , Carpas/metabolismo , Dieta/veterinaria , Inflamación/veterinaria , Alimentación Animal/análisis , Proteínas de Peces/genéticaRESUMEN
Vitamin E (VE) is an essential lipid-soluble vitamin that improves the fish flesh quality. However, the underlying molecular mechanisms remain unclear. This study aimed to investigate the effects of VE on growth performance and flesh quality in sub-adult grass carp (Ctenopharyngodon idella). A total of 450 fish (713.53 ± 1.50 g) were randomly divided into six treatment groups (three replicates per treatment) and fed for nine weeks with different experimental diets (dietary lipid 47.8 g/kg) that contained different levels of VE (5.44, 52.07, 96.85, 141.71, 185.66, and 230.12 mg/kg diet, supplemented as dl-α-tocopherol acetate). Notably, the treatment groups that were fed with dietary VE ranging from 52.07 to 230.12 mg/kg diet showed improvement in the percent weight gain, special growth rate, and feed efficiency of grass carp. Moreover, the treatment groups supplemented with dietary VE level of 141.71, 185.66, and 230.12 mg/kg diet showed enhancement in crude protein, lipid, and α-tocopherol contents in the muscle, and the dietary levels of VE ranging from 52.07 to 141.71 mg/kg diet improved muscle pH24h and shear force but reduced muscle cooking loss in grass carp. Furthermore, appropriate levels of VE (52.07 to 96.85 mg/kg diet) increased the muscle polyunsaturated fatty acid content in grass carp. Dietary VE also increased the mRNA levels of fatty acid synthesis-related genes, including fas, scd-1, fad, elovl, srebp1, pparγ, and lxrα, and up-regulated the expression of SREBP-1 protein. However, dietary VE decreased the expression of fatty acid decomposition-related genes, including hsl, cpt1, acox1, and pparα, and endoplasmic reticulum stress-related genes, including perk, ire1, atf6, eif2α, atf4, xbp1, chop, and grp78, and down-regulated the expression of p-PERK, p-IRE1, ATF6, and GRP78 proteins. In conclusion, dietary VE increased muscle fatty acid synthesis, which may be partly associated with the alleviation of endoplasmic reticulum stress, and ultimately improves fish flesh quality. Moreover, the VE requirements for sub-adult grass carp (713.53 to 1590.40 g) were estimated to be 124.9 and 122.73 mg/kg diet based on percentage weight gain and muscle shear force, respectively.
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Ochratoxin A (OTA) is a common mycotoxin in food and feed that seriously harms human and animal health. This study investigated the effect of OTA on the muscle growth of juvenile grass carp (Ctenopharyngodon idella) and its possible mechanism in vitro. Our results have the following innovative findings: (1) Dietary OTA increased the expression of increasing phase I metabolic enzymes and absorbing transporters while reducing the expression of efflux transporters, thereby increasing their residue in muscles; (2) OTA inhibited the expressions of cell cycle and myogenic regulatory factors (MyoD, MyoG, and MyHC) and induced ferroptosis by decreasing the mRNA and protein expressions of FTH, TFR1, GPX4, and Nrf2 both in vivo and in vitro; and (3) the addition of DFO improved OTA-induced ferroptosis of grass carp primary myoblasts and promoted cell proliferation, while the addition of AKT improved OTA-inhibited myoblast differentiation and fusion, thus inhibiting muscle growth. Overall, this study provides a potential research target to further mitigate the myotoxicity of OTA.
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Carpas , Ferroptosis , Enfermedades de los Peces , Ocratoxinas , Animales , Humanos , Suplementos Dietéticos , Inmunidad Innata , Transducción de Señal , Carpas/genética , Carpas/metabolismo , Dieta , Músculos/metabolismo , Alimentación Animal/análisis , Proteínas de Peces/metabolismoRESUMEN
Bacterial pathogens destroy the structural integrity of functional organs in fish, leading to severe challenges in the aquaculture industry. Vitamin D3 (VD3) prevents bacterial infections and strengthens immune system function via vitamin D receptor (VDR). However, the correlation between VD3/VDR and the structural integrity of functional organs remains unclarified. This study aimed to investigate the influence of VD3 supplementation on histological characteristics, apoptosis, and tight junction characteristics in fish intestine during pathogen infection. A total of 540 healthy grass carp (257.24 ± 0.63 g) were fed different levels of VD3 (15.2, 364.3, 782.5, 1,167.9, 1,573.8, and 1,980.1 IU/kg) for 70 d. Subsequently, fish were challenged with Aeromonas hydrophila, a pathogen that causes intestinal inflammation. Our present study demonstrated that optimal supplementation with VD3 (1) alleviated intestinal structural damage, and inhibited oxidative damage by reducing levels of oxidative stress biomarkers; (2) attenuated excessive apoptosis-related death receptor and mitochondrial pathway processes in relation to p38 mitogen-activated protein kinase signaling (P < 0.05); (3) enhanced tight junction protein expression by inhibiting myosin light chain kinase signaling (P < 0.05); and (4) elevated VDR isoform expression in fish intestine (P < 0.05). Overall, the results demonstrated that VD3 alleviates oxidative injury, apoptosis, and the destruction of tight junction protein under pathogenic infection, thereby strengthening pathogen defenses in the intestine. This finding supports the rationale for VD3 intervention as an essential practice in sustainable aquaculture.
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Flavobacterium columnare (F. columnare) is one of the deadliest fish pathogens causing bacterial gill rot disease in various freshwater fish species globally. Tea polyphenols (TPs) are an inexpensive product extracted from tea that have received much attention as a feed additive in aquaculture. The current study was designed to investigate the underlying mechanisms and protective effects of dietary TPs against F. columnare-induced gill injury via suppression of oxidative stress, apoptosis, and inflammation in grass carp. TPs were not supplemented to the diet (control) and were supplemented at 40, 80, 120, 160 or 200â¯mg/kg diet. The feeding experiment was carried out for 60â¯days, followed by a 3-Dayâ¯F. columnare challenge test. The results showed that 120â¯mg/kg TPs in the diet exerted the following five protective effects in fish gill: (1) control gill-rot disease and improved histopathology, (2) inhibit excessive apoptosis, (3) enhance the activity of antioxidant enzymes and upregulate related gene expression via the Nrf2/Keap1 pathway, (4) increase the activity of immune enzymes, And (5) mediate inflammatory cytokine gene expression via the JAK/STAT3 pathway. Taken together, dietary supplementation with TPs is a compelling approach to protect the gill function of fish against F. columnare.
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Carpas , Enfermedades de los Peces , Animales , Proteína 1 Asociada A ECH Tipo Kelch , Branquias , Factor 2 Relacionado con NF-E2 , Estrés Oxidativo , Inflamación , Apoptosis , TéRESUMEN
Copper (Cu) is a trace element, essential for fish growth. In the current study, in addition to growth performance, we first explored the effects of Cu on collagen synthesis and myofiber growth and development in juvenile grass carp (Ctenopharyngodon idella). A total of 1080 fish (11.16 ± 0.01 g) were randomly divided into 6 treatments (3 replicates per treatment) to receive five doses of organic Cu, which were Cu citrate (CuCit) at 0.99 (basal diet), 2.19, 4.06, 6.15, and 8.07 mg/kg, and one dose of inorganic Cu (CuSO4·5H2O at 3.15 mg/kg), for 9 weeks. The results showed appropriate Cu level (4.06 mg/kg) enhanced growth performance, improved nutritional Cu status, and downregulated Cu-transporting ATPase 1 mRNA levels in the hepatopancreas, intestine, and muscle of juvenile grass carp. Meanwhile, collagen content in fish muscle was increased after Cu intake, which was probably due to the following pathways: (1) activating CTGF/TGF-ß1/Smads signaling pathway to regulate collagen transcription; (2) upregulating of La ribonucleoprotein domain family 6 (LARP6) mRNA levels to regulate translation initiation; (3) increasing proline hydroxylase, lysine hydroxylase, and lysine oxidase activities to regulate posttranslational modifications. In addition, optimal Cu group increased myofiber diameters and the frequency of myofibers with diameter >50 µm, which might be associated with upregulation of cyclin B, cyclin D, cyclin E, proliferating cell nuclear antigen, myogenic determining factor (MyoD), myogenic factor 5, myogenin (MyoG), myogenic regulatory factor 4 and myosin heavy chain (MyHC) and downregulation of myostatin mRNA levels, increasing protein levels of MyoD, MyoG and MyHC in fish muscle. Finally, based on percentage weight gain (PWG), serum ceruloplasmin (Cp) activity and collagen content in fish muscle, Cu requirements were determined as 4.74, 4.37 and 4.62 mg/kg diet (CuCit as Cu source) of juvenile grass carp, respectively. Based on PWG and Cp activity, compared to CuSO4·5H2O, the efficacy of CuCit were 131.80% and 115.38%, respectively. Our findings provide new insights into Cu supplementation to promote muscle growth in fish, and help improve the overall productivity of aquaculture.
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Ochratoxin A (OTA) is a common fungal toxin that pollutes raw materials of aquatic feeds (such as corn, soybean meal, and wheat). This study explored the effects of OTA through diet on muscle toxicity in juvenile grass carp (Ctenopharyngodon idella). The following results were obtained for the muscle. (1) With an increase in dietary OTA, the residue of OTA in muscle increased, muscle fiber diameter and density decreased, and even muscle fiber breakage. (2) OTA caused oxidative stress by downregulating GPx1 (a, b) and Trx via inhibited the PGC1-α/Nrf2 signaling pathway. (3) OTA exacerbated endoplasmic reticulum stress in the muscle by causing endoplasmic reticulum expansion (results of transmission electron microscopy) and upregulating the expression of GRP78, eIF2α, ATF6, PERK, and CHOP. (4) OTA reduced muscle fiber diameter by inhibiting protein synthesis (AKT, TOR, and S6K1) and promoting the mRNA expression of protein degradation-related genes (MURF1, MAFBX, and FoxO3a), as well as by reducing AKT and promoting the immunofluorescence expression of FoxO3. (5) OTA inhibits collagen deposition by downregulating TGF-ß1, TGF-ßR1, Smad2, Smad3, Smad4, CTGF, TIMP, PHD, and LOX mRNA expressions as well as the CTGF immunofluorescence expression. Moreover, based on the GSH and collagen content contents, the upper safe dose for OTA-induced toxicity was 963.6 and 1129.6 µg/kg diet, respectively. Using the example of OTA, our research has provided new insights that raise concerns about the quality of aquatic products by exploring muscle toxicity caused by mycotoxins.
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The vertebrate mucosal barrier comprises physical and immune elements, as well as bioactive molecules, that protect organisms from pathogens. Vitamin D is a vital nutrient for animals and is involved in immune responses against invading pathogens. However, the effect of vitamin D on the mucosal barrier system of fish, particularly in the skin, remains unclear. Here, we elucidated the effect of vitamin D supplementation (15.2, 364.3, 782.5, 1167.9, 1573.8, and 1980.1 IU/kg) on the mucosal barrier system in the skin of grass carp (Ctenopharyngodon idella) challenged with Aeromonas hydrophila. Dietary vitamin D supplementation (1) alleviated A. hydrophila-induced skin lesions and inhibited oxidative damage by reducing levels of reactive oxygen species, malondialdehyde, and protein carbonyl; (2) improved the activities and transcription levels of antioxidant-related parameters and nuclear factor erythroid 2-related factor 2 signaling; (3) attenuated cell apoptosis by decreasing the mRNA and protein levels of apoptosis factors involved death receptor and mitochondrial pathway processes related to p38 mitogen-activated protein kinase and c-Jun N-terminal kinase signaling; (4) improved tight junction protein expression by inhibiting myosin light-chain kinase signaling; and (5) enhanced immune barrier function by promoting antibacterial compound and immunoglobulin production, downregulating pro-inflammatory cytokine expression, and upregulating anti-inflammatory cytokines expression, which was correlated with nuclear factor kappa B and the target of rapamycin signaling pathways. Vitamin D intervention for mucosal barrier via multiple signaling correlated with vitamin D receptor a. Overall, these results indicate that vitamin D supplementation enhanced the skin mucosal barrier system against pathogen infection, improving the physical and immune barriers in fish. This finding highlights the viability of vitamin D in supporting sustainable aquaculture.
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Carpas , Enfermedades de los Peces , Infecciones por Bacterias Gramnegativas , Animales , Dieta , Aeromonas hydrophila/fisiología , Inmunidad Innata , Vitamina D/farmacología , Proteínas de Peces/genética , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Infecciones por Bacterias Gramnegativas/veterinaria , Vitaminas/farmacología , Carpas/metabolismo , Alimentación Animal/análisis , Suplementos DietéticosRESUMEN
The n6/n3 ratios improved meat quality of terrestrial animals, but alpha-linolenic acid/linoleic acid (ALA/LNA) ratios were rarely studied in aquatic animals. In this study, sub-adult grass carp (Ctenopharyngodon idella) were fed diets fed diets containing six varying ALA/LNA ratios (0.03, 0.47, 0.92, 1.33, 1.69, and 2.15) for 9 weeks and the total value of n3 + n6 (1.98) was kept constant for all six treatments. The results indicated optimal ALA/LNA ratio improved growth performance, changed fatty acid composition in grass carp muscle, and promoted glucose metabolism. Additionally, optimal ALA/LNA ratio improved chemical attributes by increasing crude protein and lipid contents, and technological attributes by increasing pH24h value and shear force in grass carp muscle. The signaling pathways related to fatty acid metabolism and glucose metabolism (LXRα/SREBP-1, PPARα, PPARγ, AMPK) might be responsible for these changes. Dietary optimal ALA/LNA ratio based on PWG, UFA and glucose contents was 1.03, 0.88 and 0.92, respectively.
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Ochratoxin A (OTA), a notorious pollutant widely present worldwide, seriously pollutes aquafeeds. This paper aims to explore the toxicity effects of OTA by the way of diet on the skin barrier in grass carp (Ctenopharyngodon idella). Results were shown as follows in the skin: (1) OTA increased the mRNA abundances of uptake transporter proteins (e.g., OAT3) and decreased efflux transporter proteins (e.g., ABCG2), which caused the accumulation of OTA in the skin of grass carp. (2) OTA upregulated the gene expression related to ROS production by enhancing the NOX (1, 2, 4) signaling pathway and decreased the ability to ROS elimination with downregulation of GPx1 (a,b), Trx by inhibiting the PGC1-α/Nrf2 signaling pathway, which caused oxidative damage to the skin. (3) OTA exacerbated apoptosis in the skin by upregulating the expression of apoptosis-related proteins mediated by ways of endoplasmic reticulum stress and mitochondrial apoptosis. Moreover, OTA down-regulated the mRNA and protein abundances of tight junction-related proteins by inhibiting the MLCK signaling pathway, which in turn disrupted the tight junctions. (4) OTA reduced the number of mucous cup cells and decreased f LZ activities and IgM contents, and finally down-regulated the mRNA abundances of mucin (2, 3), LEAP-2 (A, B), and ß-defensin (1, 2, 3), which in turn resulted in impairing skin chemical barrier. Moreover, based on the antimicrobial-related indexes (LZ activities and IgM contents), the OTA-safe upper doses were 814.827 and 813.601 µg/kg.
RESUMEN
To further explain the improvement effect of threonine (Thr) on the fillet quality of fish, a 9-week feeding experiment was conducted. After feeding graded levels of Thr (2.38, 5.38, 8.38, 11.38, 14.38 and 17.38 g/kg), the compositions of fillet hydrolyzed amino acid and fatty acid, and the muscle hardness associated with collagen biosynthesis were mainly analyzed in grass carp (Ctenopharyngodon idella). The results showed that Thr increased the pH value, changed the amino acids and fatty acid composition of fillets, especially essential amino acid (EAA), C22:6n3 (DHA) and C20:5n3 (EPA). Furthermore, this study revealed for the first time that the improvement of muscle hardness by Thr was associated with collagen biosynthesis, and the TGF-ß1/Smads, LARP6a and Hsp47 regulate transcriptional processes, translation initiation and post-translational modifications in collagen biosynthesis, respectively. This study offered a basis for exploring the contribution of Thr in improving muscle quality in sub-adult grass carp.
Asunto(s)
Carpas , Enfermedades de los Peces , Animales , Treonina , Carpas/metabolismo , Dureza , Dieta , Aminoácidos , Músculos/metabolismo , Ácidos Grasos , Colágeno , Alimentación Animal/análisis , Suplementos Dietéticos , Proteínas de Peces/metabolismo , Inmunidad InnataRESUMEN
The prevalence of aflatoxin B1 (AFB1), one of the most toxic mycotoxins that contaminates feedstock and food is increasing worldwide. AFB1 can cause various health problems in humans and animals, as well as direct embryotoxicity. However, the direct toxicity of AFB1 on embryonic development, especially foetal foetus muscle development, has not been studied in depth. In the present study, we used zebrafish embryos as a model to study the mechanism of the direct toxicity of AFB1 to the foetus, including muscle development and developmental toxicity. Our results showed that AFB1 caused motor dysfunction in zebrafish embryos. In addition, AFB1 induces abnormalities in muscle tissue architecture, which in turn causes abnormal muscle development in larvae. Further studies found that AFB1 destroyed the antioxidant capacity and tight junction complexes (TJs), causing apoptosis in zebrafish larvae. In summary, AFB1 may induce developmental toxicity and inhibit muscle development through oxidative damage, apoptosis and disruption of TJs in zebrafish larvae. Our results revealed the direct toxicity effects of AFB1 on the development of embryos and larvae, including inhibition of muscle development and triggering neurotoxicity, induction of oxidative damage, apoptosis and disruption of TJs, and fills the gap in the toxicity mechanism of AFB1 on foetal development.