Grass Carp Ctenopharyngodon Idella Research Articles

Seasonal assessment of selected trace elements in grass carp (Ctenopharyngodon idella) blood and their effects on the biochemistry and oxidative stress markers

Environmental pollution by anthropogenic activity is still a highly relevant global problem. Aquatic animals are a specifically endangered group of organisms due to their continuous direct contact with the contaminated environment. Concentrations of selected trace elements in the grass carp (Ctenopharyngodon idella) (n = 36) blood serum/clot were monitored. Possible effects of the elements on selected biochemical and oxidative markers were evaluated. The concentrations of trace elements (Al, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Sr, Tl, and Zn) were analysed in the fish blood serum and blood clot by inductively coupled plasma optical emission spectrometry (ICP OES). A general scheme of decreasing concentrations of trace elements in the blood serum samples was: Zn ˃ Fe ˃ Sr ˃ Ba ˃ Ni ˃ Al ˃ Cu ˃ Be ˃ Co; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mn, Mo, Pb, Tl; and in the case of the blood clot, the scheme was as follows: Fe ˃ Zn ˃ Sr ˃ Al ˃ Ni ˃ Ba ˃ Cu ˃ Be ˃ Co ˃ Mn; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mo, Pb, Tl. Significant differences among the seasons were detected. The Spearman R correlation coefficients and linear or non-linear regression were used to evaluate direct relationships between trace elements and selected blood biomarkers. The correlation analysis between biochemical parameters (Na, K, P, Mg, AST, ALT, ALP, GGT, TAG, TP, urea, glucose) and trace elements (Al, Ba, Be, Cu, Fe, Ni, Sr, and Zn) concentrations confirmed statistically significant interactions in both seasons (summer and autumn). The regression analysis between oxidative stress markers (ROS, GPx, creatinine, uric acid, and bilirubin) and elements (Al, Ba, Co, Cu, Fe, Ni, and Sr) content confirmed statistically significant interactions. The results point to numerous connections between the observed elements and the physiological parameters of freshwater fish.

Hematological and Histopathological Changes of Juvenile Grass Carp (Ctenopharyngodon idella) Exposed to Lethal and Sublethal Concentrations of Roundup (Glyphosate 41% SL)

The presence of pesticides and their potential toxic effects on fish can pose a threat to aquatic ecosystems and human health. The present study aimed to evaluate the effect of commercial formulations of glyphosate (Roundup) on the survival rate, hematological parameters, and tissues (gills and liver) of juvenile grass carp (Ctenopharyngodon idella). For these purposes, we exposed the fish to 0, 50, 100, and 150 mL L−1 of Roundup for 96 hr. Results showed a significant correlation between the fish’s mortality rate and pesticide concentrations ( p &lt; 0.01 ); the LC50 96 hr of Roundup was 75.838 mL L−1 in the present study. The concentrations above 50 mL L−1 induced significant tissue lesions seen as lamellar aneurism, leukocyte infiltration, distal hyperplasia, cloudy swelling, macrophage aggregates, and necrosis in the gills and liver. We also reported a significant correlation between the severity of tissue damage and Roundup concentration. The hematocrit, hemoglobin, white, and red blood cell count significantly reduced after 96 hr of exposure to 100 and 150 mL L−1. The opposite trend was reported for concentrations of glucose, albumin, cholesterol, total protein, and triglycerides. Finally, the fish exposed to 100 and 150 mL L−1 of Roundup displayed some clinical signs, such as increasing operculum movement, darkening the skin, and swimming near the surface during the movement test. Overall, our results showed that concentrations of Roundup higher than 50 mL L−1 can induce various toxic effects and significantly reduce the survival chance of juvenile grass carp. Roundup altered fish behavior, tissue functioning, and biochemical processes. In this study, we provided some basic knowledge about the effects of a glyphosate-based herbicide on aquatic organisms and possible environmental management.

Bio-based active packaging: Gallic acid modified agarose coatings in grass carp (Ctenopharyngodon idellus) preservation

Antioxidant and antimicrobial agarose coatings were developed by grafting gallic acid through the carbodiimide coupling method. Structural characterization revealed that the carboxyl group of gallic acid was successfully grafted onto the C6-OH of D-galactose in agarose, with the highest observed grafting ratio being 13.73 %. The grafting of gallic acid significantly increased the antioxidant and bacteriostatic activities of the agarose. As the grafting ratio of gallic acid-modified agarose (GaAg) increased from 0 to 13.73 %, the scavenging ratio of DPPH and the inhibition ratio of β-carotene bleaching were observed to increase from 0 % to 65.92 % and 6.89 % to 73.46 %, respectively. GaAg exhibited up to 100 % inhibition of Escherichia coli and Staphylococcus aureus. The physicochemical properties of gel strength, viscosity, gelling temperature and melting temperature decreased to 971.3 g/cm2, 17.9 mPa·s, 31.7 °C and 84.1 °C, respectively. The gel contact angle was increased from 22.1° to 73.6°. Fish preservation tests have demonstrated that it effectively inhibited bacterial growth, prevented fat oxidation, blocked light, reduced moisture loss, and enhanced the overall quality of grass carp (Ctenopharyngodon idellus) fillets during refrigeration, which was more effective than native agarose in extending the shelf life of fish. Therefore, GaAg holds promise as an aquatic product preservative.

Immunomodulation of potassium diformate in juvenile grass carp (Ctenopharyngodon idella) after Aeromonas hydrophila infection: T-cell differentiation and cytokine production

Potassium diformate (KDF) is a green and safe feed additive to replace antibiotics in animal. Although a few studies have found that KDF improved disease resistance, the specific mechanisms have not been explored in depth. Therefore, the study aims to examine the effects of KDF on immune defense substances, inflammatory process, T cell differentiation, and related molecular expression in fish. The juvenile grass carp were selected from six groups after feeding graded levels of KDF (0.0, 1.5, 3.0, 4.5, 6.0 and 7.5 g/kg) for 70 days. Then 6-day challenge experiment was performed by intraperitoneal injection Aeromonas hydrophila. Appropriate levels of KDF increased the lysozyme and acid phosphatase activities, the complement 3 and complement 4 contents in the head kidney and spleen of juvenile grass carp. Meanwhile, Appropriate addition levels of KDF down-regulated the abundances of TNF-α, IL-2, IL-6, IL-8, IL-1β, IL-12, IL-22, IL-17D, T-bet and RORγt (RORγ2) mRNA and up-regulated the abundances of TGF-β, IL-4, IL-10, GATA3, FOXP3, CD4, MHCIIα and MHCIIβ mRNA in the head kidney and spleen. Besides, appropriate levels of KDF down-regulated the mRNA levels of IKKγ (not IKKα), IKKβ, NF-κB p65 (not p52), STAT1, STAT4, and the protein level of NF-κB p65, up-regulated the mRNA levels of IκBα, JAK1, JAK2, JAK3, STAT3b1, STAT3b2 (not STAT3a), STAT5b, STAT6, and the protein level of p-STAT3Tyr705. The appropriate levels of KDF enhanced the immune defense and mediated the inflammatory process that might be related to T cell differentiation probably via JAK-STATs and NF-κB signalings in fish.

Docosahexaenoic acid (DHA) inhibits abdominal fat accumulation by promoting adipocyte apoptosis through PPARγ-LC3-BNIP3 pathway-mediated mitophagy

Obesity has always been an overwhelming health concern worldwide. Docosahexaenoic acid (DHA) reduces abdominal fat accumulation by inducing adipocyte apoptosis, but the underlying mechanism remains unclear. Mitophagy, the process of maintaining mitochondrial homeostasis, has a double-edged sword effect that positively or negatively regulates apoptosis. In this study, grass carp (Ctenopharyngodon idellus) was used as an animal model to investigate the role of mitophagy in regulating apoptosis and the potential molecular mechanisms for DHA-induced mitophagy in vivo and in vitro. Firstly, we found that DHA induced the intrinsic apoptosis in grass carp adipocytes, accompanying by activating BNIP3/NIX-mediated mitophagy. Then, suppression of mitophagy alleviated apoptosis and eliminated the inhibition of lipid accumulation induced by DHA in vivo and in vitro. Mechanistically, the DHA-induced mitophagy was caused by activating PPARγ and its DNA binding capacity to the LC3 promoter, which promoted the interaction of BNIP3 (rather than NIX) with LC3. However, the inhibition of PPARγ in vitro significantly decreased the expression of autophagy-related genes (P < 0.05), reducing the colocalization of mitochondria and lysosomes while preventing BNIP3/NIX-mediated mitophagy-mediated apoptosis and subsequently alleviating the inhibition of lipid accumulation in adipocytes induced by DHA. For the first time, we demonstrated that DHA activates mitophagy by regulating the PPARγ-LC3-BNIP3 pathway, consequently inducing apoptosis, which decreases adipocytes, inhibiting lipid accumulation in grass carp. These findings provide new insight into the mechanism of DHA-induced apoptosis mediated by mitophagy as the potential therapeutic target of inhibiting abdominal fat accumulation in vertebrates.

A Review of Grass Carp and Related Species Literature on Diet, Behavior, Toxicology, and Physiology Focused on Informing Development of Controls for Invasive Grass Carp Populations in North America

Grass carp (Ctenopharyngodon idella) are globally important in aquaculture and aquatic vegetation control. However, escaped grass carp have established invasive populations. A targeted keyword search was performed on a carp (order: Cypriniformes) literature database maintained by the U.S. Geological Survey to identify literature relevant to grass carp. Additional sources cited in reviewed documents and provided by numerous reviewers were also included. There were three focus areas designed to provide support for invasive grass carp management: (1) diet and behavior; (2) physiological constraints, toxicity, and biology; and (3) gut physiology. Each focus area provides information to guide development of potential pathways for invasive grass carp control. Information from other carp species was used to fill in gaps where grass carp information was lacking and provide additional, potential research directions. Diet-related information included food selection and aquacultural diet formulations. Behavioral information included stimuli and non-physical barriers to attract, repel, or stop movement. Physiological constraints, toxicology, reproductive control, and biological control provide a research review for control options. Gut physiology and related control pathways provide knowledge to improve toxin or pathogen delivery. This review provides a basis for developing approaches and research for controlling invasive grass carp populations, aquaculture, and native population management.

Age-related morphological and ultrastructural changes in the palate and pharyngeal masticatory apparatus of grass carp (Ctenopharyngodon idella) juveniles

Grass carp (Ctenopharyngodon idella or C. idella) is a Cyprinid fish frequently utilized for aquaculture, medical, and research purposes. In C. idella, the palate is followed by a well-developed pharyngeal masticatory apparatus. The latter consists of an upper chewing pad superimposing a paired set of teeth. The present study investigated morphological, morphometric, histochemical, and surface ultrastructural changes involving these structures in C. idella juveniles at three different timepoints namely 35 mm total length (TL; 59 days posthatching (dph); fry-fingerling transition), 70 mm TL (90 dph; fingerling), and 210 mm TL ( 365 dph: yearling). The palatal epithelium revealed a constant number of taste buds. However, the height and width of these buds revealed an age-dependent increase. The number of palatal acidic goblet cells increased gradually with age. Enhanced keratinization of pad epithelium, and increased teeth dimensions were age-associated characteristics. Ultrastructurally, the palatal surface of C. idella was slightly papillated at 35 mm TL after which it formed brick-like structural units that tended to cluster into longitudinally paralleled rows toward the palate-pad junction. Goblet cell openings appeared oval at 35 mm TL and became club-shaped by 210 mm TL at which the epithelium appeared compact and heavily coated in mucus. Indentations of pad surface and signs of dental wear and tear were evident ultrastructurally at 70 mm TL and onwards. The current study reports for the first time age-related developmental features of the palate and pharyngeal masticatory apparatus of grass carp. Results of the present work will help to understand aging-associated factors involving the studied fish and other related aquatic species.

Molecular characterization and dietary regulation of the forkhead box O3 (foxo3a and foxo3b) in grass carp (Ctenopharyngodon idella)

The forkhead box O3 (foxo3) regulates the target genes expression involved in regulating cell cycle and biological metabolism. In the study, foxo3a and foxo3b of grass carp (Ctenopharyngodon idella) were cloned. The foxo3a cDNA have a complete open reading frame (ORF) spanning 1431 bp, which encodes a polypeptide of 476 amino acids. The foxo3b cDNA contains a complete ORF encompassing 1959 bp, encoding a protein consisting of 652 amino acid residues. The analysis of genetic codon preference and phylogenetic relationships revealed that the foxo3a and foxo3b genes in grass carp are closely related to the counterparts of Danio rerio and Megalobrama amblycephala. Tissue expression analysis showed that foxo3a expression reached the maximum in the brain while foxo3b expression in the muscle being the highest. Circadian expression pattern showed that, foxo3a expression presented a periodic upward trend from 3:00–9:00, 12:00–18:00 and 21:00–24:00, and the maximum level of foxo3b was detected at 9:00. Moreover, dietary regulation of foxo3a and foxo3b expression were performed in our research. In the feeding trial with different protein sources, the groups of fishmeal, rapeseed meal and soybean meal are in contrast to each other. Foxo3a expression was significantly higher in fish fed with rapeseed meal compared to those fed with soybean meal and fishmeal at 14th and 21st days of the experiment. Foxo3b expression was highest in the fishmeal group, followed by rapeseed meal, while it was lowest in soybean meal at 14th and 28th days. Analysis of the effect of dietary alanine-glutamine dipeptide on foxo3 expression in grass carp revealed that the expression of foxo3a gradually increased with increasing dietary Ala-Gln dipeptide concentration and reached its highest level at a concentration of 1.5%. Conversely, foxo3b expression significantly decreased when the dipeptide concentration reached 2%. The findings of this study may provide new insights into the molecular properties, spatiotemporal dynamics, and nutritional regulation of foxo3 in fish.

Dietary nano-selenium improves health of liver and intestine of grass carp Ctenopharyngodon idella after overwintering

The purpose of this study was to examine the effects of nano-selenium (nano-Se) on the health of liver and intestine of grass carp (Ctenopharyngodon idella) after overwintering. Grass carp were fed three diets contained 0 mg/kg (control group, Se0), 0.3 mg/kg (Se0.3) and 0.6 mg/kg (Se0.6) nano-Se for 60 days before the overwintering. After overwintering, evaluation of the Se deposition, biochemical parameters, histopathology, and the expression of genes involved in inflammation, oxidative stress and tight junctions were performed. The results showed that the content of Se in the liver and intestine were significantly increased as dietary nano-Se level increased. The addition of 0.3 and 0.6 mg/kg nano-Se significantly reduced the levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and malondialdehyde (MDA) in the serum (P < 0.05). The activities of catalase (CAT) and glutathione peroxidase (GSH-Px) were significantly increased and the content of MDA was significantly decreased in the liver by 0.3 and 0.6 mg/kg dietary nano-Se (P < 0.05). In the intestine, the activity of GSH-Px was significantly increased and the content of MDA was significantly decreased by 0.6 mg/kg dietary nano-Se (P < 0.05). The histological results showed that dietary nano-Se alleviated the inflammatory cell infiltration of hepatocytes. The addition of 0.6 mg/kg nano-Se significantly down-regulated the expressions of tlr2, tlr4 and nf-κb p65, and up-regulated the expression of il-10 in the liver of grass carp after overwintering (P < 0.05). The expressions of ifn-γ, tgf-β1 and il-6 in the liver were significantly reduced by adding 0.3 and 0.6 mg/kg dietary nano-Se (P < 0.05). The addition of nano-Se reduced the structural disturbance and the pathological phenomena such as atrophy and adhesion in the intestine. At the same time, nano-Se significantly increased the villus height in the intestine (P < 0.05). Nano-Se also enhanced barrier function of intestine by up-regulating the expression of zo-1 (P < 0.05). Besides, the expressions of tlr2, nf-κb p65, ifn-γ and tnf-α in the intestine were significantly down-regulated by adding 0.6 mg/kg dietary nano-Se (P < 0.05). The expressions of gpx4a and gpx4b in the intestine were significantly decreased by adding 0.3 mg/kg dietary nano-Se (P < 0.05). In conclusion, nano-Se effectively improved the liver and intestine health of grass carp after overwintering by reducing oxidative stress and inflammation, and improving intestinal tight junction, thereby reducing the weight loss of grass carp after overwintering.

Unlocking the secrets of crude myofibril-bound serine protease from grass carp: The role in degrading myofibrillar proteins

Grass carp (Ctenopharyngodon idella) are used as raw material for conventional surimi products in Southern China. However, endogenous serine proteases deteriorated the texture of the surimi gel. To unlock the mechanism behind, the present study isolated the crude myofibril-bound serine protease (cMBSP) in grass carp and studied its effects on surimi gel. The cMBSP activity was the highest at 40 °C and pH 8.0, and it remained stable at 20–55 °C neutral pH. Additionally, it was susceptible to serine protease inhibitors and high concentrations of Na+. The maximum degradation of myosin heavy chain by cMBSP was observed at 50 °C. Protein unc-45 homolog B (a myosin chaperone) is one of the apparent degradation products according to mass spectrometry. The cMBSP caused lower water holding capacity and deteriorated texture in the surimi gel. This study expanded insights about the mechanism of surimi gel degradation by cMBSP, which provided theoretical basis for enhancing surimi quality.

Comparative Transcriptomic Analysis Revealed Potential Differential Mechanisms of Grass Carp Reovirus Pathogenicity.

Grass carp reovirus (GCRV), one of the most serious pathogens threatening grass carp (Ctenopharyngodon idella), can lead to grass carp hemorrhagic disease (GCHD). Currently, GCRV can be divided into three genotypes, but the comparison of their pathogenic mechanisms and the host responses remain unclear. In this study, we utilized the Ctenopharyngodon idella kidney (CIK) model infected with GCRV to conduct comparative studies on the three genotypes. We observed a cytopathic effect (CPE) in the GCRV-I and GCRV-III groups, whereas the GCRV-II group did not show any CPE. Moreover, a consistent trend in the mRNA expression levels of antiviral-related genes across all experimental groups of CIK cells was detected via qPCR and further explored through RNA-seq analysis. Importantly, GO/KEGG enrichment analysis showed that GCRV-I, -II, and -III could all activate the immune response in CIK cells, but GCRV-II induced more intense immune responses. Intriguingly, transcriptomic analysis revealed a widespread down-regulation of metabolism processes such as steroid biosynthesis, butanoate metabolism, and N-Glycan biosynthesis in infected CIK cells. Overall, our results reveal the CIK cells showed unique responses in immunity and metabolism in the three genotypes of GCRV infection. These results provide a theoretical basis for understanding the pathogenesis and prevention and control methods of GCRV.

Recombinant surface display vaccine enhances the immersion immune effect against grass carp reovirus in grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella) is subject to a hemorrhagic disease caused by grass carp reovirus (GCRV), which can lead to mass mortality in grass carp culture, causing significant economic loss. Vaccination is the most promising strategy for the prevention of infectious diseases. Immersion vaccination is considered the most effective disease prevention method for juvenile fish because it can be implemented on many fish at once and administered without causing stress. However, immune responses by immersion vaccination are markedly less robust due to the skin barrier and insufficient antigen uptake. The display of heterologous proteins on the cell surface has been explored as a delivery system for viral antigens in veterinary and human vaccine studies. To improve the efficacy of the immersion vaccine, the major capsid protein (VP7) of GCRV was co-displayed with Aeromonas hydrophila outer membrane protein a (OmpA) and major adhesion protein (Mah) on the outer membrane surface of nonpathogenic Escherichia coli BL21 using the anchoring motif of ice-nucleation protein (Inp). The immune responses and protection efficiency against GCRV infection via both the injection and immersion routes were evaluated. The results indicated that the activities of anti-oxidant enzymes (ACP, AKP, SOD and T-AOC), as well as the expression of immune-related genes (TNF-α, IL-1β, MHCI and IgM) and specific VP7 antibody levels, were strongly increased in the grass carp from 7 to 21 days post-injection inoculation in a dose dependent manner. The cumulative mortality rates of injection-vaccinated groups were much lower than those of the control group after the GCRV challenge, and the relative percent survival (RPS) was greater than 80 %. Vitally, the surface co-display of vp7-Mah protein conferred marked protection to grass carp against GCRV infection after immersion administration (RPS >50 %); this was consistent with the production of high level of specific serum antibodies, non-specific immune responses, and the expression of immune-related genes. Moreover, the invasion analysis further showed that surface co-display of the vp7-Mah protein indeed significantly improved the invasion of E. coli BL21 (DE3) in vitro. Altogether, this study demonstrated that surface display GCRV core antigen vaccine system accompanied by invasion component from aquatic pathogenic microorganism is an effective prophylactic against GCRV viral diseases via the immersion administration approach.

Lpla (lipoprotein lipase a) is a marker of early adipogenesis rather than late adipogenesis in grass carp (Ctenopharyngodon idellus).

Lipoprotein lipase (LPL) functions as a marker of adipocyte differentiation in mammals, but little is known about its role in fish adipogenesis. The aim of this research is to investigate the function of Lpl in adipocyte differentiation in fish. In this paper, we isolated and characterized lipoprotein lipase a (lpla) and lipoprotein lipase b (lplb) from grass carp (Ctenopharyngodon idellus). The complete coding sequence of lpla and lplb was 1524 bp and 1503 bp in length, coding for 507 amino acids and 500 amino acids, respectively. Both lpla and lplb mRNA were expressed in a great number of tissues. During adipogenesis, the level of lpla mRNA reached its maximum at day 2 and then dropped gradually, while the level of lplb mRNA had no significant changes, indicating that lpla and lplb may have different function in the differentiation of grass carp adipocyte. Furthermore, inhibition of lpla by inhibitor of LPL(GSK264220A) at early time points most clearly reduced adipogenesis, whereas these effects were less pronounced at later stages, suggesting that lpla predominantly affects early adipogenesis rather than late adipogenesis. Based on these findings, it can be inferred that lpla and lplb in grass carp may have distinct roles in the differentiation of grass carp adipocyte, and lpla may play an important role in the early adipogenesis rather than late adipogenesis in grass carp.

Microbiota composition and correlations with environmental factors in grass carp (Ctenopharyngodon idella) culture ponds in South China.

To maintain the health of aquaculture fish, it is critical to understand the composition of microorganisms in aquaculture water and sediment and the factors affecting them. This study examined the water and sediment microbiota compositions of four different types of ponds in South China that were used to culture grass carp (Ctenopharyngodon idella) of different sizes through high-throughput sequencing of the 16S rRNA gene, and analyzed their correlations with environmental factors. The results showed that ponds with cultured grass carp of different sizes exhibited significant differences in terms of water physicochemical properties and composition of water and sediment microbiota. Furthermore, the exchange of microorganisms between water and sediment microbiota was lowest in ponds with the smallest grass carp and highest in ponds with the largest grass carp. All detected environmental factors except water temperature were significantly correlated with the water microbiota, and all detected environmental factors in the sediment were correlated with sediment microbiota. Moreover, Aeromonas hydrophila and Vibrio were significantly increased in the water microbiota, especially in ponds with small juvenile grass carp, implying an increased risk of A. hydrophila and Vibrio infections in these environments. Our results provide useful information for the management of grass carp aquaculture ponds.

Genotoxicity of Copper, Silver and Green Synthetic Gold Nanoparticles in Fish (Ctenopharyngodon idella).

Grass carp (Ctenopharyngodon idella) was exposed to nanoparticles of different concentrations, i.e., copper oxide nanoparticles (CuO-NPs), silver nanoparticles (Ag-NPs), and green synthetic gold nanoparticles (Au-NPs).The administered doses of the three concentration groups were 20mg L-1, 30 mg L-1, and 40mg L-1 each for a period of 14 and 28 days, respectively. The DNA damage in the erythrocytes of grass carp was detected through a comet assay technique. The values of total comet score (TCS) were noted for the exposed concentrations with a significant increasing trend (p < 0.05) and ordered as CuO-NPs > Ag-NPs > Au-NPs. The highest TCS value of the exposed erythrocytes was recorded for CuO-NPs at 40 mg L-1 after 14 days of exposition period. Comparatively, TCS values of erythrocytes exposed to green synthetic Au-NPs at all the concentrations and exposed time were less as compared to the Ag-NPs and CuO-NPs. The study confirmed the adverse effects of nanoparticles on the genetic material of fish cells.

Docosahexaenoic acid (DHA) alleviates hepatic lipid accumulation by regulating mitochondrial quality control through ERK signaling pathway in grass carp (Ctenopharyngodon idellus)

Docosahexaenoic acid (DHA) alleviates hepatic lipid accumulation in fish, but the underlying mechanism remains unclear. Studies in mammals showed that promoting fatty acid (FA) β-oxidation, which mainly occurs in mitochondrion, improves lipid accumulation. This study aims to investigate the effect of DHA on fatty acid (FA) β-oxidation, focusing on the role of hepatic mitochondrial quality control (MQC) and mitochondrial function, in grass carp (Ctenopharyngodon idellus) in vivo and in vitro. Grass carps (41.87 ± 0.08 g) were fed with diets supplemented with 0% (control) and 1% DHA for 8 weeks. Dietary 1% DHA markedly decreased the hepatosomatic index, hepatic triglyceride (TG) content, and serum TG (P < 0.05). Dietary 1% DHA significantly increased pparα and cpt1 mRNAs, which implies the activated FA β-oxidation. In addition, dietary 1% DHA improved mitochondrial function by increasing the ATP content and antioxidant ability. The mRNAs encoding DRP1, OPA1, MFN1 and MFN2 were significantly increased by DHA (P < 0.05), suggesting that mitochondrial division and fusion were activated simultaneously. Transmission electron microscopy displayed that dietary 1% DHA triggers the increase of mitochondria. Along with this, mitochondrial DNA copy numbers and the mRNA expression of pgc1α, tfam and nrf1 were significantly increased in 1% DHA group (P < 0.05), suggesting that DHA activated mitochondrial biogenesis. BNIP3/NIX-dependent mitophagy was also induced by DHA. Consistent with these in vivo results, DHA restored the loss of ATP content, mitochondrial membrane potential, and antioxidant ability in palmitic acid (PA)-treated hepatocytes in vitro, implying that DHA improved the MQC network damaged by PA. DHA further activated FA β-oxidation and inhibited lipid accumulation in the hepatocytes. Importantly, U0126, an inhibitor of ERK, abrogated the effects of DHA on the MQC network and lipid metabolism. Taken together, the present study demonstrated that the alleviation of hepatic lipid accumulation by DHA is mediated by the activation of FA β-oxidation and improvement of MQC via the ERK pathway. This study may shed light on the molecular mechanism underlying DHA's function in relieving hepatic lipid deposition in vertebrates.

Freshness evaluation of grass carp by volatile biogenic amines monitored by secondary electrospray ionization ion mobility spectrometry

In this paper, a secondary electrospray ionization ion mobility spectrometry (SESI-IMS) method using ammonium acerate was evaluated for rapid determination of the various volatile biogenic amine contents in grass carp (Ctenopharyngodon idella). The ammonium ion generated by electrospray ionization source functions as reactant ion to react with volatile biogenic amines in gas phase and separated in the drift tube. The SESI-IMS method requires minimum sample preparation and minimum interferences, and volatile biogenic amines show their unique drift times without overlapping. The content of volatile biogenic amines demonstrates good correlations with storage times at 4 ℃ and 8 ℃ cold storage. It is shown that trimethylamine and putrescine are the dominant biogenic amines during the cold storage process. Other freshness indicates including sensory evaluation, hardness, pH and total volatile basic nitrogen (TVB-N) also show good consistency with volatile biogenic amines. The developed method is a rapid, simple, and sensitive method for the determination of volatile biogenic amines in grass carp.

Nucleophosmin 1a translocated from nucleus to cytoplasm and facilitate GCRV replication

To decipher the functional characterization of Nucleophosmin 1a (NPM1a) from grass carp (Ctenopharyngodon idellus) (CiNPM1a), its cDNA was cloned and bioinformatic analysis were conducted. The full-length cDNA sequence of CiNPM1a is 1732 bp, which encodes 307 amino acids. CiNPM1a contains conserved domains of Nucleoplasmin domain, NPM1-C terminal domain, as well as nuclear localization signals, nuclear export signal (NES) and acid patches. There are 52 and 20 consensus amino acids exist in the Nucleoplasmin domain and the NPM1-C terminal domain of all blasted species. In addition, the immune function of CiNPM1a were analyzed. The Ciirf7, Ciifn1 and Ciifn2 transcription was inhibited, whereas the vp2 and vp7 expressions were enhanced in CiNPM1a overexpressing cells after GCRV infection (P < 0.05). Moreover, the Ciirf7, Ciifn1 and Ciifn2 mRNA levels were significantly up-regulated, but the vp2 and vp7 expressions were significantly down-regulated in CiNPM1a knockdown cells after infection. This indicated that CiNPM1a played negative roles in the induction of Type I IFN reaction and thus the GCRV replication. Finally, the NES domain that affect the nucleous-cytoplasm shuttle and the replication of GCRV were investigated. The deletion of NES1 and NES(1 + 2+3) absolutely limited the transloacation of CiNPM1a△NES1 protein and CiNPM1a △NES(1 + 2+3) protein to cytoplasm after infection, and the deletion of NES2 resulted in partially limitation of protein shuttle. In general, Ciirf3, Ciirf7, Ciifn1 and Ciifn2 expressions were enhanced in the CiNPM1a△NES1, CiNPM1a△NES2 and CiNPM1a△NES3 overexpression groups, and the deletion of functional domains in CiNPM1a led to significantly reduction of the vp2 and vp7 replication. The results indicated that CiNPM1a may be a target molecular for GCRV infection curation, and a candidate molecular for resistance strain breeding of grass carp.

The effect of broad bean diet on structure, flavor and taste of fresh grass carp: A comprehensive study using E-nose, E-tongue, TPA, HS-SPME-GC-MS and LC-MS

Broad bean (Vicia faba L.) has received particular attention with regards to the improvement of flesh meat quality. However, the effect of broad bean diet on structure, flavor and taste of flesh meat is unclear. In present study, E-nose, E-tongue, TPA, HS-SPME-GC-MS, and LC–MS were used to characterize the structure, flavor and taste of grass carp (Ctenopharyngodon idellus) fed with broad bean. Overall, broad bean significantly improved the texture of grass carp muscle, but reduced the overall taste and flavor. The 50 volatile compounds were detected using HS-SPME-GC-MS. The 252 differential metabolites were identified by LC-MS, of which 107 were up-regulated and 145 were down-regulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated this reduction in taste and flavor was associated with the metabolism of amino acids, lipids and nucleotides. Our findings provide a theoretical basis for improving meat quality and the functional applications of broad bean.

Re-identification and characterization of grass carp Ctenopharyngodon idella TLR20

Toll-like receptors (TLRs) play a crucial role in the recognition of microbial-associated molecular patterns in the innate immune system. Fish TLRs have undergone significant gene expansion to adapt to complex aquatic environments. Among them, TLR20 from the TLR11 family actively responds to viral and bacterial invasions. Previous studies have reported two TLR20s in grass carp (Ctenopharyngodon idella), and in this study, we revised this conclusion. Based on the latest grass carp genome, we identified a new TLR20 member. These three TLR20s are arranged in tandem on chromosome 9, indicating that they are generated by gene duplication events. They were renamed CiTLR20.1 to CiTLR20.3 based on their chromosomal positions. The CiTLR20s in C. idella exhibit higher similarities with those in Danio rerio, Cyprinus carpio, and Megalobrama amblycephala, and lower similarities with those in other distantly related fish species. Selective pressure analysis revealed low conservation and negative evolution of TLR20s during evolution. The 3D structures of the three TLR20s showed significant differences, reflecting functional variations and different downstream adaptor molecule recruitment. Transcriptome data revealed tissue distribution differences of TLR20s, with TLR20.1 showing relatively low expression levels in all the tissues, while TLR20.2 and TLR20.3 showed higher expression in the head kidney, spleen, and gill. Additionally, TLR20.2 and TLR20.3 actively responded to GCRV-II infection, with higher upregulation of TLR20.2 in response to Aeromonas hydrophila challenge. In conclusion, this study corrected the number of grass carp TLR20 members and analyzed TLR20 from an evolutionary and structural perspective, exploring its role in antiviral and antibacterial defense. This study provides reference for future research on fish TLR20.