Grass Carp Research Articles

Analysis of GCRV Pathogenesis and Therapeutic Measures Through Proteomic and Metabolomic Investigations in GCRV-Infected Tissues of Grass Carp (Ctenopharyngodon idella)

Hemorrhagic disease caused by grass carp reovirus (GCRV) infection is a major problem affecting the grass carp aquaculture industry. Therefore, inhibiting the spread of GCRV infection is of great economic significance. Herein, we sequenced five tissues (gill, liver, intestine, kidney, and muscle) from grass carp before and after GCRV infection using data-independent acquisition proteomic and untargeted metabolomic technologies, and quantitatively identified 10,808 proteins and 4040 metabolites. Then, we analyzed the differentially expressed proteins (DEPs) and metabolites (DEMs) before and after GCRV infection in the five tissues. Gene ontology analysis revealed that the five tissue DEPs were enriched in metabolic, including carbohydrate and lipid metabolic processes. Chemical taxonomy analysis showed that the categories of DEMs mainly included carbohydrates and lipids, such as fatty acids, glycerophospholipids, steroids, and their derivatives. Both the proteomic and the metabolomic data showed that GCRV affected the carbohydrate and lipid metabolism in the host. Shared pathway analysis was performed at both the protein and metabolic levels, showing significant enrichment of the glycolysis and pentose phosphate pathways (p < 0.001). Further analysis of glycolysis and pentose phosphate pathway inhibitors revealed that these two pathways are important for GCRV replication. As the kidney was the most affected among the five tissues, we analyzed the butanoate metabolism in the kidney, which revealed that most of the differentially expressed proteins and differently expressed metabolites in the butanoate metabolism were related to the TCA cycle. Further investigation showed that fumaric acid, an intermediate product in the TCA cycle, significantly inhibited GCRV replication in the CIK cells (p < 0.001), and that this inhibitory effect may be related to its induction of interferon system activation. The addition of fumaric acid to feed increased the survival rate of juvenile grass carp by 19.60% during GCRV infection, and protected the tissues of those infected with GCRV, making it a potential anti-GCRV feed additive. Our results provide new perspectives on GCRV pathogenesis and antiviral strategies for grass carp.

Spatiotemporal Ultrastructural, Histological, and Morphometric Changes in the Buccal Cavity of Grass Carp (Ctenopharyngodon idella) During Fingerling, Yearling, and Adult Stages

Grass carp (Ctenopharyngodon idella) is a Cyprinid fish of aquacultural and research importance. The buccal cavity represents the gateway of the digestive tract. The present study investigated the adaptational changes involving various components of the buccal cavity of fingerling (three months posthatching, mph), yearling (12 mph), and adult (48 mph) C. idella using scanning electron microscopy, histology, and morphometry. The upper and lower lips appeared uninterrupted at the three studied stages and were limited caudally by the upper and lower jaws. The jaw epithelium was the thickest part of the buccal epithelium; ultrastructurally, it appeared smooth with ridge-like borders in fingerlings that transformed into microgrooves in yearlings. In adult C. idella, the jaw mucosa was organized into dome-shaped masses separated from each other by tight furrows. Each mass was formed from several keratinocytes with corrugated surfaces that featured numerous microdepressions. Except for the jaws, taste buds, mainly of type I, and acidic and neutral goblet cells were observed throughout the mucosa of the buccal cavity, and their densities were highest along the mucosal folds of the palate and oral floor, suggesting a principal role for these parts in both gustation and food lubrication. This study is the first to report age-associated spatiotemporal changes in the buccal cavity of grass carp and will serve as a fundamental reference during the interpretation of various types of oral pathologies in teleost.

Toxicity of a management bait for grass carp (Ctenopharyngodon idella) incorporated with Antimycin A.

No current technology can specifically target grass carp (Ctenopharyngodon idella) for control within aquatic ecosystems. Rotenone and Carbon Dioxide-Carp are currently the only available registered pesticides for grass carp; they are nonselective and typically applied throughout the water, equally exposing target and native species. A more selective control tool or pesticide application could be used by resource managers to support mitigation efforts. Development of delivery systems that exploit carp feeding strategies could increase selectivity of pesticides and minimize effects on native fishes. A pesticide with selective delivery could be less labor intensive and used within an integrative pest management strategy. The present study examined Antimycin A toxicity in juvenile and sub-adult grass carp and rainbow trout (Oncorhynchus mykiss) across two routes of exposure. Water-based toxicity studies were used to calculate the concentration to cause lethality in 50% of treated fish (LC50) at 24-h, while oral gavage toxicity studies were used to calculate the dose to cause lethality in 50% of treated grass carp and rainbow trout (LD50) 24- to 96-h. Although rainbow trout were more sensitive than grass carp to Antimycin A through water-based exposure, oral toxicity was similar between species, even with inherent gastrointestinal morphological differences. Successful delivery of a lethal dose of Antimycin A to grass carp was achieved through an oral route of exposure using the rapeseed bait and shows promise for registration as a control tool and eventual use in pest management plans. Although a lethal dose of Antimycin A could be incorporated into a single bait pellet, more bait was required to achieve desired mortality when fed to fish under laboratory conditions.

CLIP-FSSC: A Transferable Visual Model for Fish and Shrimp Species Classification Based on Natural Language Supervision

Fish and shrimp species classification is a practical need in the field of aquaculture. Traditional classification method includes extracting modal features of the single image and training them on downstream datasets. However, this method has the disadvantage of requiring manual annotated image data and significant training time. To address these issues, this paper introduces a method named CLIP-FSSC (Contrastive Language–Image Pre-training for Fish and Shrimp Species Classification) for zero-shot prediction using a pre-trained model. The proposed method aims to classify fish and shrimp species in the field of aquaculture using a multimodal pre-trained model that utilizes semantic text description as an image supervision signal for transfer learning. In the downstream fish dataset, we use natural language labels for three types of fish - grass carp, common carp, and silver carp. We extract text category features using a transformer and compare the results obtained from three different CLIP-based backbones for the image modality - vision transformer, Resnet50, and Resnet101. We compare the performance of these models with previous methods that performed well. After performing zero-shot predictions on samples of the three types of fish, we achieve similar or even better classification accuracy than models trained on downstream fish datasets. Our experiment results show an accuracy of 98.77%, and no new training process is required. This proves that using the semantic text modality as the label for the image modality can effectively classify fish species. To demonstrate the effectiveness of this method on other species in the field of aquaculture, we collected two sets of shrimp data - prawn and cambarus. Through zero-shot prediction, we achieve the highest classification accuracy of 92.00% for these two types of shrimp datasets. Overall, our results demonstrate that using a multimodal pre-trained model with semantic text description as an image supervision signal for transfer learning can effectively classify fish and shrimp species with high accuracy, while reducing the need for manual annotation and training time.

The pasture system improves natural antioxidants and functional lipids while reducing lipid peroxidation in Ctenopharyngodon idella (grass carp) burgers during storage

C. idella burgers made from a pasture-based system provide a natural method for producing high-quality fish products, resulting in meat enriched with polyunsaturated fatty acids, particularly EPA and DHA, as well as fat-soluble vitamins and antioxidants. In this study, C. idella meat burgers were made from two types of diets: pasture-based (PS) and grain-based (GS). A total of 36 burgers were stored in plastic trays (three burgers per tray; 12 trays per group), in a refrigeration chamber at 4 °C ± 0.1 °C for 120 h to conduct a shelf-life experiment comparing the meats. Initial fatty acid profile and nutritional composition were determined at 0 h. Additionally, fat-soluble vitamins, antioxidants, TBA, and FRAP were measured at 0, 24, 48, 72, 96, and 120 h. PS burgers exhibited higher concentrations of n-3 LC-PUFAs, vitamins, antioxidants, except for gamma-tocopherol, and FRAP than GS burgers (P < 0.05), while GS burgers had higher TBA and γ-tocopherol (P < 0.05). Both burgers experienced vitamin reduction during storage, with PS burgers maintaining higher concentrations. Vitamin decline correlated with increased oxidation (TBA) in both burger types. These results suggest that pasture-fed burgers have longer shelf life than GS burgers due to reduced oxidation and enhanced stability of bioactive compounds.

Protective effect of betaine supplementation in low-met diet against Aeromonas hydrophila-induced intestinal injury in grass carp (Ctenopharyngodon idella)

This study evaluated the effect of supplemental betaine in low-methionine (Met) diet concerning the regulatory role of bacteria-induced intestinal injury in fish. 540 grass carp (Ctenopharyngodon Idella) (210 ± 0.68 g) were selected and randomly divided into 6 groups, which contained a reference group fed with the diet supplemented with DL-Met (3.1 g kg−1 diet) and 5 groups fed on the diets added with increasing levels of betaine (0–6.4 g kg−1 diet) for 60 days. Then, a 14-day Aeromonas hydrophila challenge was conducted. Compared with BET0 group, results indicated that appropriate betaine supplementation (1) enhanced antioxidant enzymes activities (except glutathione S-transferase pi-1 (GSTP1) and copper zinc superoxide dismutase (CuZnSOD) and glutathione (GSH) contents, and NF-E2-related-factor 2 (Nrf2) protein nuclear translocation, while reduced reactive oxygen species (ROS), and representative oxidative damage markers; (2) up-regulated the transcription abundance of anti-apoptosis-related molecules while reduced DNA-ladder occurrence and the transcription levels of pro-apoptosis-related genes; (3) down-regulated the transcription of tight junction-related proteins (such as zonula occludens-1 (ZO-1) etc.) in fish intestines. Furthermore, correlation analysis revealed that feeding betaine ameliorating the oxidative damage, apoptosis and tight junction breakdown was possibly related to intestinal Nrf2, p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinases (JNK), and myosin light chain kinase (MLCK) signaling, respectively. According to the regression analysis for intestinal ROS abundance, claudin-b and caspase-2 transcription, the appropriate betaine supplementations were estimated to be 3.82, 3.98, and 3.62 g kg−1 diet, respectively. Notably, betaine has the potential to spare part Met and the efficacy of betaine relative to Met was 206.67 % based on intestinal ROS contents in grass carp (210–776 g).

Enhancing Aquaculture Productivity through Integrated Farming Systems: A Comparative Study of Fish-Pig and Fish-Duck Systems

Integrated farming systems involving fish-animal are of high relevance in current scenario. Studies like this asses the suitability of such systems in improving the aquaculture productivity and overall benefits to the ecosystem. It plays a crucial role in optimizing the use of small water resources in rural areas to enhance animal production. Given the potential of pig and duck manure as nutrient inputs in fish culture, a grow-out trial was conducted in a 0.1 ha earthen pond located in Elangitampatty, Kezhisenkattupatti, and Asakkattuppatti villages of Kollihills Taluk in Namakkal district, Tamil Nadu. The pond was stocked with four carp species: Catla, Rohu, Mrigal, and Grass carp in a ratio of 40:20:30:10 at a density of 7500 fish per hectare. Three treatments were employed: (1) Control (T0), where fish were fed with commercial feed, (2) Integrated fish-duck farming (T1), and (3) Integrated pig-fish farming (T2). In the control group (T0), fish were fed commercial fish feed (24% crude protein, 4 mm pellet size) at 4% of body weight, while in T1 and T2, fish received 50% of the commercial feed and were supplemented with duck and pig excreta, respectively. After an 8-month grow-out period, fish weights and total production in each group were recorded. Water quality parameters, such as pH, dissolved oxygen, free carbon dioxide, alkalinity, and hardness, were measured using standard methods (APHA, 2019). Results showed that pond fertilization with pig and duck excreta promoted the growth of algae, phytoplankton, and zooplankton, providing a natural food source for the fish. Total fish production was highest in the fish-pig integration system (T2), with a recorded yield of 4960.09 kg. Catla (Catla catla) had the highest individual species yield, with a total harvested weight of 2225.98 kg, followed by Grass carp (Ctenopharyngodon idella) at 1490.37 kg. The final average weight of Grass carp in T0, T1, and T2 was 1047 ± 13.27 g, 1151.10 ± 12.85 g, and 1490.37 ± 13.52 g, respectively. For Catla, the final average weight in T0, T1, and T2 was 910 ± 9.45 g, 960 ± 10.26 g, and 980 ± 12.20 g, respectively. Similarly, Rohu in T0, T1, and T2 weighed 850 ± 7.98 g, 900 ± 11.23 g, and 910 ± 11.16 g, respectively, while Mrigal in T0, T1, and T2 weighed 600 ± 6.04 g, 720 ± 8.50 g, and 730 ± 10.56 g, respectively. The results highlight that the fish-pig system outperformed the fish-duck system in terms of fish productivity, which may be due to the better nutrient composition in pig manure and the genetic potential of the fish species. An economic analysis revealed that the fish-pig integration system generated the highest net income (Rs. 555,353.90) and benefit-cost ratio (2.12), indicating that integrated fish-pig farming is more profitable than both fish-duck farming and the control group without integration.

Insights into Decapod Sentience: Applying the General Welfare Index (GWI) for Whiteleg Shrimp (Penaeus vannamei—Boone, 1931) Reared in Aquaculture Grow-Out Ponds

The rapid growth of shrimp farming, particularly of Penaeus vannamei, accounts for about 80% of the global production of farmed shrimp and involves the cultivation of approximately 383 to 977 billion individuals annually, which highlights the urgent need to address the ethical and technical implications of raising potentially sentient beings. This study builds on the state-of-the-art assessment of sentience, consciousness, stress, distress, nociception, pain perception, and welfare to adapt the General Welfare Index (GWI) for farmed shrimp. The GWI is a quantitative index developed by our research group to measure the degree of welfare in aquaculture, and it has been previously applied to grass carp and tilapia. Using the PRISMA methodology and the creation of a hypothetical shrimp farm, the GWI, with 31 specific and measurable indicators across various welfare domains, is adapted to P. vannamei, offering a comprehensive assessment framework. The inclusion of quantitative welfare indicators promises to improve living conditions in alignment with legislation adopted on decapods’ sentience and contemporary scientific advances.

Investigating the Influence of Specific Heavy Metals on the Haemato-Biochemical and Genotoxic Traits of Grass Carp

Investigating the Influence of Specific Heavy Metals on the Haemato-Biochemical and Genotoxic Traits of Grass Carp

Comparative behavioral responses of grass carp (Ctenopharyngodon idella), bighead carp (Hypophthalmichthys nobilis), and silver carp (H. molitrix) to free amino acids in water.

Control and elimination of invasive fishes, like carps (Order Cypriniformes), may be possible by using chemical stimuli to congregate them for removal. To this end, we tested behavioral responses of grass (Ctenopharyngodon idella), bighead (Hypophthalmichthys nobilis), and silver carp (H. molitrix) to L-alanine, L-arginine, L-glutamic acid, and L-aspartic acid. In grass carp, the first three amino acids have been shown to be beneficial for growth, and all four produce a strong olfactory response in this species. This study used pairs of conspecific fish in a video-recorded, sound-insulated, clear acrylic, tube-shaped tank; during trials, an amino acid stimulus was delivered at one end of that tank. Changes in space use, velocity, and acceleration across all amino acids differed significantly among species. Changes in space use by grass carp indicated avoidance of only two amino acids, L-alanine and L-aspartic acid. There was no evidence for attraction to amino acids for grass or silver carp. For bighead carp, change in spatial use on exposure to amino acids indicated attraction across the four amino acids. This attraction was enhanced by lowered velocity. Our results suggested that olfactory sensitivity does not directly translate to behavioral responses. Other sensory cues, for example tactile, visual, and/or taste, may mediate the selective foraging of grass carp. Amino acids may serve as a better olfactory attractant for bighead carp compared to grass or silver carp.

Effect of Temperature on Black Carp (Mylopharyngodon piceus) Age at Sexual Maturity

ABSTRACTBlack Carp (Mylopharyngodon piceus) is one of the four invasive Asian Carp species (Bighead Carp, Hypophthalmichthys nobilis; Grass Carp, Ctenopharyngodon idella; and Silver Carp, Hypophthalmichthys molitrix) in North America. As benthic predators, Black Carp poses ecological risks to unionids within the Great Lakes and could bring other changes to local benthic communities. One means of assessing invasion risk and potential impact is to determine how critical life history characteristics depend on environmental conditions in new regions. Age at sexual maturity is negatively correlated to the maximum per capita population growth rate and thus can be used to estimate potential population growth for invasive species. Previous studies have found a significant negative relationship between age at maturity and temperature for all three other Asian Carp species, but not for Black Carp. With a more comprehensive dataset, we demonstrate that the same relationship exists for Black Carp. Winter duration is the best predictor of Black Carp age at maturity, followed by average winter air temperature. This significant relationship between age at maturity and temperature was not altered in artificial growing environments. Our results suggested that for Black Carp, temperatures in the winter months are more important for its energy accumulation and maturation and may determine invasion risk in northern locations, such as tributaries of the Great Lakes.

Edwardsiella piscicida promotes mitophagy to escape autophagy-mediated antibacterial defense in teleost monocytes/macrophages

Edwardsiella piscicida is a Gram-negative intracellular pathogen. Currently, the immune evasion strategies of E. piscicida are not yet fully understood. In this study, we revealed that E. piscicida exploited mitophagy to enhance its intracellular survival in grass carp (Ctenopharyngodon idella) monocytes/macrophages. The results showed that in E. piscicida-infected cells, there was a significant loss of mitochondrial membrane potential and a marked increase in the production of mitochondrial reactive oxygen species (mtROS), indicating the damage to the mitochondria in the infected cells. Furthermore, fluorescence confocal images presented that E. piscicida infection elicited the colocalization of mitochondria with microtubule-associated protein 1 light chain 3 (LC3, a key marker molecule of autophagy) and lysosomes, suggesting the occurrence of mitophagy. This notion was supported by the findings that E. piscicida significantly stimulated LC3-II protein and damped Tom20 (a marker molecule of mitochondria) protein levels. Subsequently, a mitophagy inducer carbonyl cyanide m-chlorophenyl hydrazine (CCCP) and a mitophagy inhibitor mitochondrial division inhibitor 1 (Mdivi-1) were used to evaluate the role of mitophagy in modulating the intracellular survival of E. piscicida. The results revealed that CCCP significantly promoted intracellular survival of E. piscicida, whereas Mdivi-1 hindered the bacterial growth. Moreover, Mdivi-1 further increased the production of bacteria-induced mitochondrial ROS in an additive manner. In particular, CCCP suppressed and Mdivi-1 promoted the colocalization of LC3-II with E. piscicida, implying that E. piscicida-triggered mitophagy to facilitate its growth probably by subverting the autophagy targeting this bacterium, a previously known clearance pathway of E. piscicida. Overall, our findings suggest a new survival strategy employed by E. piscicida within fish monocytes/macrophages.

An emerging role of ferulic acid on sub-adult grass carp (Ctenopharyngodon idellus): Increasing protein digestion and regulating amino acid and oligopeptide transporters expression

This study was conducted to evaluate the effect of supplement ferulic acid on growth performance, digestive ability and transport function of amino acids and oligopeptides in the intestine of sub-adult grass carp (Ctenopharyngodon idellus). The experiment was divided into two parts: a. Digestion experiment: healthy grass carp (678.83±1.00 g) were divided into two groups: control group (0 mg/kg FA) and ferulic acid group (100 mg/kg FA) for 2 weeks; b. Growth experiment: healthy grass carp (678.83±1.00 g) were divided into five treatment groups, the control group (FA0) with no ferulic acid and the experimental group supplemented with ferulic acid 50 (FA50), 100 (FA100), 150 (FA150) and 200 (FA200) mg/kg feed for 9 weeks. The results showed that a. Ferulic acid supplementation increased the apparent digestibility of crude protein and crude fat in grass carp. b. Ferulic acid supplementation improved the growth performance and feed efficiency (FE) of grass carp; increased the activities of trypsin and Na+/K+-ATPase; and up-regulated the levels of mRNAs of some neutral and cationic (non-anionic) amino acid transporter proteins (Solute Carrier Family7member1 (SLC7A7), SLC7A8, etc.) and H+/oligopeptide transporter protein 1 (PepT1) gene and protein levels. In addition, ferulic acid promoted the gene expression levels of protein kinase B (Akt), target of rapamycin (TOR); up-regulated the mRNA levels of tail-side-associated homologous frame transcription factor 2 (Cdx2), cAMP response element-binding protein (CREB), and transcriptional co-activator-specific protein 1 (Sp1), and down-regulated the gene and protein levels of protein kinase CβII (PKCβII). In a word, dietary ferulic acid promoted growth performance, digestion, as well as amino acid and oligopeptide transport capacities. Finally, based on regression analyses of percentage weight gain (PWG), FE, specific growth rate (SGR), intestine fold height, trypsin activity, and Na+/K+-ATPase activity, we recommend optimal supplementation levels of ferulic acid in sub-adult grass carp of 92.18–120.60 mg/kg diet.

New records of nine monogenean parasites infesting non-native freshwater fish species in New Zealand

ABSTRACT Twenty-one non-native freshwater fish species have established populations in New Zealand, yet only two have been reported with monogenean infestations; grass carp, Ctenopharyngodon idella (Valenciennes in Cuvier and Valenciennes, 1844) and western mosquitofish, Gambusia affinis (Baird and Girard, 1853), each with two identified monogenean species. Based on the diversity of monogeneans known from New Zealand's non-native freshwater fish species in their native and other invaded ranges, it is likely that many other monogeneans could be extant in the country. Accordingly, we surveyed monogeneans from seven freshwater fish species. Eleven monogenean species were found, including nine previously unreported from New Zealand. One represented a genus previously unrecorded in the country, the ancyrocephalid Ligictaluridus pricei (Mueller, 1936), infesting the gills of Ameiurus nebulosus (Lesueur, 1819). Six dactylogyrid monogenean species were found infesting Carassius auratus (L.): Dactylogyrus anchoratus (Dujardin, 1845), D. dulkeiti Bychowsky, 1936, D. formosus Kulweic, 1927, D. inexpectatus Izyumova, 1955, D. intermedius Wegener, 1909 and D. vastator Nybelin, 1924. Further, a Gyrodactylus species was observed from the gills of Carassius auratus, which could not be confidently identified to the species level. Finally, Dactylogyrus minutus Kulweic, 1927, was recorded from Cyprinus rubrofuscus Lacépède, 1803.

Escherichia coli heat-labile enterotoxin B subunit as an adjuvant of mucosal immune combined with GCRV-II VP6 triggers innate immunity and enhances adaptive immune responses following oral vaccination of grass carp (Ctenopharyngodon idella)

The grass carp reovirus (GCRV) is the most major pathogen that has threatened the grass carp (Ctenopharyngodon idella) industry of China for years. Though the oral vaccine has many advantages, the current vaccines still do not provide complete protection. Therefor the exploration of new preventive strategies is urgently needed. In this study, heat-labile enterotoxin B subunit of Escherichia coli (LTB) was combined with VP6 from GCRV type II (GCRV-II) via Lactococcus lactis expression system to form a potent oral vaccine and determines if fusion of LTB to the protective vaccine antigen can enhance protection in the fish. The expression of recombinant protein was confirmed by Western-blotting and enzyme-linked immunosorbent assay. The rare minnow was set as the model for the evaluation of the experiment administrated orally. The immune response including the antibody titer and the immune-related gene expression, and the protective efficacy which included the virus loaded and the relative protection, were thoroughly investigated after the trial. The results indicated that LTB can significantly elicit a higher neutralizing antibody responses and enhanced T-cell priming, activities and proliferation in mononuclear cells from intestine, spleen and kidney tissues when compared to the VP6 vaccine alone. Moreover, the combined adjuvant can significantly up-regulate type I interferon signaling in different immune organs, especially the mucosa associated lymphoidtissue which could not be induced by VP6 along, result in the contribution of the improvement in adaptive immune responses of the fish. In addition, challenge study showed that LTB combined VP6 could greatly improve the relative percent survival of the fish during the virus infection. These results highlight that LTB has the potential value to be a mucosal adjuvant of the fish, approaching for improving the efficacy of vaccination against GCRV-II, which does elicit both non-specific and specific immune responses.

Investigating the metabolism of four sulfonamides in grass carp via HPLC-MS for screening candidate materials of matrix reference material

An efficient, sensitive, and precise method for investigating the metabolism of four sulfonamides in grass carp has been established using high-performance liquid chromatography-mass spectrometry. By optimizing the experimental conditions, the method achieved a coefficient of determination above 0.999, with detection and quantification limits set at 0.5 μg/kg and 1.0 μg/kg, respectively. Recovery rates were between 92.90 % and 102.84 %, and relative standard deviations ranged from 1.70 % to 9.83 %, enabling the precise detection of these sulfonamides in grass carp tissue. The factors affecting the metabolic rate during the medicated bath process were investigated, and obtained the optimal parameter conditions for screening the candidate materials. The candidate materials screened through this method exhibit good stability when used to prepare matrix standard substances, this work not only provides a scientific basis for screening sulfonamide candidate materials but also offers insights for developing other matrix reference materials.

Detrimental effects of glyphosate on muscle metabolism in grass carp (Ctenopharyngodon idellus)

Glyphosate, a commonly used herbicide, has been associated with environmental pollution and potential health risks to aquatic organisms. This study investigated the effects of glyphosate on the muscle metabolism of grass carp (Ctenopharyngodon idellus) following exposure to environmentally relevant concentrations. Over a 14-day exposure period to varying glyphosate levels, significant disruptions were observed in antioxidant capacity and muscle health. These disruptions were evidenced by reductions in total antioxidant capacity (T-AOC), increases in malondialdehyde (MDA) levels, and decreases in activities of glutathione peroxidase (GSH-PX) and catalase (CAT). Furthermore, exposure to glyphosate resulted in a reduction of vitamin E content and an elevation of hormonal levels, suggesting the potential for endocrine disruption. Metabolomics analysis identified 605 distinct metabolites, with notable alterations in amino acid, carbohydrate, and nucleotide metabolism pathways. Specifically, arginine and glutathione metabolisms were severely impacted, with decreases in key amino acids such as glycine and glutathione at higher glyphosate concentrations. Nucleotide metabolism, particularly purine synthesis, was also significantly affected, with reduced levels of deoxyguanosine and other purine-related compounds. The study further investigated the origins of these differential metabolites using the MetOrigin platform, suggesting a potential involvement of the intestinal microbiota in the metabolic response to glyphosate. These findings highlight the multifaceted adverse effects of glyphosate on fish muscle, including oxidative stress and metabolic dysregulation, which may contribute to diminished muscle quality and health risks for aquatic organisms.

Comparative analysis of Seabuckthorn and its significant component in enhancing fish mucosal immunity

Seabuckthorn and its significant component, gallic acid, were found to alleviate foodborne enteritis in zebrafish, a model species. To investigate the protective effects on mucosal immunity in cultured fish, seabuckthorn or gallic acid was added to soybean meal feed in a study conducted on juvenile grass carp. After a 5-week feeding trial, histopathology, enteritis-related gene expression, transcriptomics, and 16S rRNA gene sequencing were performed on the hindgut and liver tissues. The results showed that dietary inclusion of seabuckthorn (9.5 g/kg) or gallic acid (1.2 g/kg) prevented enteritis, evidenced by an increase in intestinal villi length and a decrease in goblet cell numbers. The gallic acid group showed benefits in preserving villi length, while seabuckthorn was advantageous in controlling goblet cells. On the molecular level, downregulation of pro-inflammatory genes and upregulation of anti-inflammatory genes were observed. Specifically, seabuckthorn was more effective in controlling cytokine expression, while gallic acid better protected the epithelial barrier function. Omics analysis revealed an upregulated hepatic “PPAR signaling pathway” in the seabuckthorn group and downregulated intestinal “platelet activation” in the gallic acid group, suggesting reduced inflammation and improved immune homeostasis. Regarding intestinal microbiota, both groups showed reduced pathogenic Campilobacterota and Aeromonas, and increased Bacteroides and Cetobacteria, potentially enhancing mucosal immunity. For anti-inflammatory processes, hepatic “fatty acid degradation”, “tryptophan metabolism”, and “FoxO signaling pathway” were elevated only in the seabuckthorn group. Gallic acid was advantaged with more “mitophagy” and “autophagy”. Fish-fed seabuckthorn or gallic acid were challenged with Aeromonas hydrophila to assess impacts on other mucosal surfaces. In the gill, compared to the soybean meal group, significantly higher survival rates, reduced CD4 inflammatory signals, and increased filament space were observed. Comparing seabuckthorn with its active component, seabuckthorn performed better in lipid metabolism, resistance to A. hydrophila, anti-inflammation, and probiotic abundance, while gallic acid mainly showed benefits for mucosal barrier protection, such as increased gill filament space. In summary, seabuckthorn and gallic acid improved mucosal immunity in fish, particularly in the gut and gills, enhancing resistance to bacterial infection and foodborne inflammation. Thus, gallic acid and seabuckthorn may be optimal phytotherapy choices in aquaculture.

Probiotic Strain Lactobacillus plantarum GCLP4 Derived From the Gut of Ctenopharyngodon idella Modulates Growth, Digestive Enzymes and Immune-Biochemical Parameters of Labeo rohita Fingerlings.

The present study was carried out to isolate, identify, and characterize bacterial probiotic strain from the gut of Ctenopharyngodon idella (Grass carp) and then to study its effect on growth, digestive enzymes and immunity of Labeo rohita fingerlings. A total of 6 gram-positive bacteria belonging to the genus Lactobacillus spp. (3), Bacillus spp. (2) and Staphylococcus spp. (1), were identified biochemically. Based on the biochemical results, the isolate GCLP4 was selected for molecular confirmation and BLAST analysis showed maximum homology with Lactobacillus plantarum (100% ident). Fish were fed for 60 days with diet containing 0 (T0), 105 (T1), 107 (T2), 109 (T3) cfu/g diet of L. plantarum GCLP4 and 105 (T4) of commercial probiotics. Results shows that supplementation of GCLP4 had significantly (p < 0.05) improve weight gain (%), specific growth rate (SGR) and feed conversion ratio (FCR) of L. rohita with better values in T3 group. The immunological parameters (white blood cell, red blood cell, haemoglobin, total protein, albumin and globulin were significantly higher (p < 0.05) with 107 and 109 Lactobacillus GCLP4 cfu/g diet. The digestive enzyme activities (protease, amylase and lipase) were significantly (p < 0.05) higher, particularly, with 109 Lactobacillus GCLP4 cfu/g of diet. All the groups supplemented with GCLP4 including the commercial probiotics have lower (p < 0.05) activities of serum transaminase enzymes along with lower (p < 0.005) level of glucose as compared to the control group. The results of the study collectively suggest that dietary L. plantarum GCLP4 at 109 cfu/g is an effective probiotic obtained from grass carp having potency to promote growth, digestive enzymes and immune-biochemical indices of L. rohita fingerlings in present culture condition.

Preparation and immunological study of Ichthyophthirius multifiliis β-tubulin DNA vaccine in grass carp (Ctenopharyngodon idella)

Grass carp, a common aquatic species in China, suffer significant annual losses due to infection by the parasitic ciliate Ichthyophthirius multifiliis (Ich), thus necessitating effective prevention and control measures. In the present study, the Ich β-tubulin gene was cloned and inserted into the eukaryotic expression vector pVAX1 plasmid to construct the Ich β-tubulin DNA vaccine (pVAX1-Bt). After two doses of the pVAX1-Bt vaccine, the relative percentage survival (RPS) reached 70.0 %, whereas the RPS after 2 doses of pVAX1 reached 10.0 %. The β-tubulin antibody, specific antibody IgM, and immune enzymes (MDA, SOD, CAT, ACP, AKP, and cortisol) were tested over13 weeks. The findings revealed a significant enhancement in the vaccinated fish compared to their unvaccinated counterparts, indicating that the vaccine can activate the humoral immune pathway and non-specific immunity in fish, thereby promoting the production of specific antibodies and memory B cells. Collectively, these results indicate that the Ich β-tubulin DNA vaccine has potential in treatment of Ich infection (ichthyophthiriasis).