Hepatopancreas Of Fish Research Articles

Effects of a potential host gut-derived probiotic, Bacillus amyloliquefaciens AV5, on the growth, biochemical and metabolic responses, and disease resistance of Nile tilapia (Oreochromis niloticus)

The influence of the dietary probiotic Bacillus amyloliquefaciens AV5 on the growth, biochemical and metabolic responses, and disease resistance of Nile tilapia (Oreochromis niloticus) was evaluated. The commercial diet (GC), a diet containing 106 and 108 CFU/g of B. amyloliquefaciens AV5, denoted as G1 and G2, respectively, was fed for 30 days. Fish were allocated to 9 plastic tanks, and each diet was randomly assigned to triplicate groups of 40 fish (22.4 ± 1.3 g).After 30 days of the feeding trial, the specific growth rate, weight gain rate, and final weight increased significantly in G2 compared to those in GC and G1. Feed conversion ratio was significantly higher in the fish-fed GC group than in the G2 group. However, the survival rate of the fish ranged from 99.13 % to 97.17 %, with no significant difference. Glucose levels did not differ significantly (P < 0.05). Total antioxidant capacity (T-AOC), (superoxide dismutase (SOD), and catalase (CAT), as well as digestive enzymes (trypsin, lipase, and protease), were significantly increased in the G2 group relative to the GC and G1 groups.Significantly lower ALT, AST, CHO, TG, and MDA activities were observed in the G2 group than in the GC group. To evaluate the metabolomic response, PCA, OPLS-DA, and volcano plots revealed a distinct difference between the G2 and GC diets, suggesting that the G2 diet impacted the hepatopancreas of fish. Furthermore, challenge experiments revealed that fish fed B. amyloliquefaciens AV5 exhibited substantially increased resistance (P < 0.05) to S. agalactiae at a concentration of 1x108CFU/g. Therefore, dietary supplementation with B. amyloliquefaciens AV5 enhanced the growth performance, metabolic activity, and disease resistance of O. niloticus.

Effect of Scoparia dulcis Extract on Lipid Oxidation in Fish Feed, Growth Performance, and Hypoxia Tolerance in Juvenile Jian Carp (Cyprinus carpio var. Jian)

Lipid oxidation and hypoxia can lead to oxidative damage in aquatic animals. This study explored the effects of Scoparia dulcis extracts (SDE) on lipid oxidation, fish growth performance, digestive ability, antioxidant capacity, and hypoxia tolerance ability. The results showed that SDE decreased malonaldehyde (MDA), conjugated diene (CD), and peroxide value (PO) in the linoleic acid and linolenic acid as well as in fish feed. Broken-line analysis revealed that the optimal acetone extract of S. dulcis (AE) supplements was 4.02, 4.01, and 4.01 g kg−1 determined from PO, CD, and MDA, respectively. Dietary AE supplementation increased feed intake and specific growth rate and activities of amylase, trypsin, and lipase as well as alkaline phosphatase in fish hepatopancreas and gut. Polynomial regression analysis showed that optimal dietary AE supplement was 3.61 g kg−1 diet determined from weight gain. Furthermore, dietary AE supplementation decreased MDA content and increased glutathione content and the activities of glutathione peroxidase, catalase, superoxide dismutase, and glutathione reductase in fish digestive organs, gills, erythrocytes, and muscle. Dietary AE supplementation increased durative time (DT) and oxygen consumption rate (OCR) under hypoxia condition. Based on polynomial regression analysis, optimal dietary AE supplements were 4.73 and 4.60 g kg−1 diet determined from DT and OCR for hypoxia tolerance in fish, respectively. According to our current research, SDE’s antioxidant capacity may be attribute to their phenolic chemicals.

Inhibitory Effect of Prickly Ash (Zanthoxylum bungeanum) Seed Kernel Oil on Lipid Metabolism of Grass Carp (Ctenopharyngodon idellus) in High-Fat Diet

To investigate the effect of prickly ash (Zanthoxylum bungeanum) seed kernel oil (PASO) on the lipid metabolism of grass carp (Ctenopharyngodon idellus) under a high-fat diet, PASO were added into two lipid-level (4 g/kg and 8 g/kg) diets to form four isonitrogenous diets: soybean oil (SO), PASO, high-fat soybean oil (HSO), and high-fat prickly ash seed oil (HPASO). A total of 216 healthy grass carp (9.43 ± 0.82 g) were randomly divided into four groups and fed with the four diets, respectively, for 56 days. The result showed that the viscerosomatic index (VSI) and the content of the crude lipid in the hepatopancreas and muscle was significantly higher by oil levels (p &lt; 0.05). The linolenic acid content in the body of the fish significantly increased in PASO and HPASO compared to that in SO and HSO (p &lt; 0.05). The fatty acid composition of the hepatopancreas, intraperitoneal fat, and muscle in four dietary groups was significantly similar to the fatty acid composition in the diets (p &lt; 0.05). More significant fat infiltration and nuclear translocation in the hepatopancreas of fish was found in the HSO group but was decreased in the HPASO group. The adipocyte size in the intraperitoneal fat tissue in the PASO group was significantly lower than that in the SO group (p &lt; 0.05). The relative mRNA expression of the lipogenesis-related genes ppar-γ, cebp-α, and srebp-1c was significantly down-regulated in the PASO group compared with the SO group (p &lt; 0.05), and the mRNA expression of lipolysis-related genes ppar-α and cpt-1 were significantly up-regulated in the PASO group (p &lt; 0.05). In conclusion, dietary PASO showed the function of reducing lipid accumulation in the fish. This reduction might be attributed to the inhibition of the lipogenesis-related genes and the stimulation of the lipolysis-related genes, which were probably modulated by the high content of linolenic acid in PASO.

Effects of dietary bacterial culture of fengycin-producing Bacillus subtilis on growth performance, intestinal and hepatopancreas health, intestinal microbiota and disease resistance of common carp (Cyprinus carpio)

Probiotics are important for the normal physiological functions of fish and are used as feed additives in many aquatic animals. The purpose of this study is to explore the effects of dietary bacterial culture of fengycin-producing Bacillus subtilis (B. subtilis) on growth performance, intestinal and hepatopancreas health, intestinal microbiota and disease resistance of common carp (Cyprinus carpio). Three diets were formulated with supplementation of bacterial culture of fengycin-producing B. subtilis at 0, 0.3 and 0.5 g/kg levels, and these diets were defined as control, BS0.3 and BS0.5, respectively. After 6-week feeding, the infiltration of inflammatory cells was improved in the BS0.3 and BS0.5 groups. And the anti-inflammatory cytokines (interleukin (IL)-10 and tumor growth factor β (TGF-β) were prominently increased in the hepatopancreas of fish fed with dietary B.subtilis diets (P < 0.05). The activity of lysozyme, the levels of complement component (C) 3 and C4 were remarkably increased in the hepatopancreas and intestine of fish fed with B.subtilis supplemented diets (P < 0.05). Histological (intestinal villi height was increased in BS0.3 and BS0.5 groups) (P < 0.05) and the expression of the gut physical barrier-related genes (Zona occludens-1 (ZO-1) and occludin) were increased in the B.subtilis supplemented groups (P < 0.05). The expression of pro-inflammatory cytokines (IL-1β, IL-6 and tumor necrosis factor α (TNF-α) and anti-inflammatory cytokines (IL-10 and TGF-β) were remarkably up-regulated in the intestine of fish fed with BS0.3 diet (P < 0.05), while the expression of IL-6 was remarkably diminished in the intestine of fish fed with BS0.5 diet (P < 0.05). Besides, the intestinal microbiota analysis illustrated that in the intestine of the fish groups fed with BS0.3 and BS0.5 diets, the abundance of Fusobacteriota and Cetobacterium were prominently increased (P < 0.05). After challenged with Aeromonas veronii Hm091, the survival rate of fish fed with BS0.3 diet was markedly improved (P < 0.05). Based on these results, supplementation of bacterial culture of fengycin-producing B. subtilis at a level of 0.3 g/kg has beneficial effects on immunity, intestinal microbiota, and disease resistance of common carp.

Blood plasma proteins and the content of metabolites of carbohydrate and lipid metabolism in the hepatopancreas of fish during the action 19-nortestosterone

The aim: study the effect of the synthetic anabolic steroid 19-nortestosterone on the fractional composition of blood plasma proteins, as well as the total protein and albumin content, indicators of the metabolism of carbohydrates, lipids, macro- and microelements in the fish hepatopancreas. Materials and methods. The experiments were conducted on two-year-old carp (Cyprinus carpio L.), which were kept for 24 hours in aquariums with a volume of 40 dm3 with different concentrations of 19-nortestosterone in water at optimal temperature, oxygen content, and pH. Spectrophotometric methods and an automatic biochemical analyzer were used to determine metabolic indicators in fish, and disk electrophoresis in PAGE was used to determine the fractional composition of proteins. Results. It was established that the steroid hormone 19-nortestosterone, the concentration of which in the water of the fish of the experimental groups was 50 and 200 μg/dm3, respectively, increased the level of total protein and albumin, the concentration of glucose, triglycerides, creatinine, inorganic phosphorus and iron in the hepatopancreas and did not affect the calcium content . In the blood plasma of carp, kept in water with a concentration of 19-nortestosterone of 50 μg/dm3, the content of proteins with a molecular weight of 240-231 increases; 215-179; 169-146 and 105-95 kDa, decreases - 35-33 kDa, fractions of proteins with a molecular weight of 228-220 appear; 116-105 and 48-44 kDa. An increase in the concentration of 19-nortestosterone in water to 200 μg/dm3 increased the content of proteins with a molecular weight of 240-231 and 215-179 kDa in the blood plasma of fish, and decreased it by 35-33 kDa, causing the redistribution of individual protein fractions due to the appearance of proteins with a molecular weight of 240 -228; 116-105 and 48-44 kDa in the absence of proteins 42-41; 38-36 and 24-20 kDa. Conclusions. Based on the obtained results, it was concluded that the anabolic synthetic steroid 19-nortestosterone stimulates the biosynthesis of proteins, the metabolism of carbohydrates and lipids, and its effect on the content of minerals in the hepatopancreas and the fractional composition of blood plasma proteins in carp fish was proven

Effects of dietary lipid levels on lipid accumulation and health status of adult Onychostomamacrolepis

The effects of different dietary lipid levels on lipid accumulation, inflammatory response, serum bio-chemical index and histological features of intestine and hepatopancreas of O.macrolepis was experimentally evaluated in an eight-weeks study. Fish (initial weight 50.11 ± 2.86 g) were fed with five iso-nitrogenous diets (around 390 g/kg protein) varying with lipid level (5%, 7%, 9%, 11%, 13%, being LL5, LL7, LL9, LL11, and LL13 respectively) in triplicates. Results showed that the content of crude lipid in carcass and hepatopancreas were not affected by dietary lipid levels (P > 0.05). Serum ALT, TP, HDL-c and MDA, etc., were not significantly affected by diets (P > 0.05), while serum total antioxidant capacity in LL9 and LL11 groups were significantly higher than the other groups (P < 0.05). Histological features of hepatopancreas and intestine showed no significant difference among the five diets (P > 0.05), while the height of intestine villus showed the higher trend in LL9 compared with other groups. The relative expression of lipid metabolism related genes (ppar α, cpt-1α, fas, and hsl) and immune response related genes (tlr 22, nrf 2, tnfα, and il-γ) in the hepatopancreas of fish fed diets differing in their crude lipid levels were not significantly different (P > 0.05). The results suggested that a proper dietary lipid level of 9%–11% could maintain higher antioxidant and health status of adult O.macrolepis.

The Effect of Echinacea Purpurea L. (Eastern Purple Coneflower) Essential Oil on Hematological Parameters and Gut Microbial Population of Zebrafish (Danio Rerio) With Aflatoxicosis

Background: Aflatoxin is one of the most important fungal toxins with documented hepatotoxic, teratogenic, and immunosuppressive properties. This mycotoxin is mainly produced by species of the genus Aspergillus in feed. Therefore, the application of compounds, which prevent complications of aflatoxins without losing feed quality, is highly beneficial. Objectives: This study aimed to determine the effect of the Echinacea purpurea L. essential oils on the regulation of the microbial population of the gastrointestinal tract and some blood factors of aflatoxin-fed zebrafish. Methods: Zebrafish were divided into four groups of 45 fish in three replicates: control (G1); G2, fish fed with feed containing 500 µg/kg E. purpurea L. essential oils; G3, fish fed with feed containing 500 µg/kg E. purpurea L. essential oil and 3 ppm aflatoxin B1(AFB1); and G4, fish fed with feed containing 3 ppm AFB1. The fish were fed with diets for 60 days. After this period, they were euthanized, blood was collected from the tail vein, and blood smears were prepared. Fish hepatopancreas were used to measure alanine aminotransferase, aspartate transaminase, and alkaline phosphatase enzymes with an auto-analyzer. Also, intestinal contents were cultured to evaluate microbial population. Results: Results showed that liver enzymes increased in the aflatoxin group (P&lt;0.05), and concurrent use of the essential oil along with AFB1 reduced the liver enzymes compared with the AFB1-treated group. Moreover, AFB1 could convert the microbial population to pathogens. Differential blood counts in the G2 and G3 groups showed an increase in the percentages of neutrophils and thrombocytes. Conclusion: According to the results of this study, E. purpurea L. essential oils could reduce the adverse effects of chronic contamination with AFB1 in zebrafish. Nevertheless, more studies are needed to better understand the immunological function of E. purpurea L. in zebrafish and its mechanism of action against AFB1.

Hepatopancreas toxicity and immunotoxicity of a fungicide, pyraclostrobin, on common carp

Pyraclostrobin (PYR), a strobilurin fungicide, has been widely used to control fungal diseases, posing potential risk to aquatic organisms. However, the toxic effects of PYR to fish remained largely unknown. In this study, common carp (Cyprinus carpio L.) was exposed to environmentally relevant levels of PYR (0, 0.5 and 5.0 μg/L) for 30 days to assess its chronic toxicity and potential toxicity mechanism. The results showed that long-term exposure to PYR induced hepatopancreas damage as evident by increased in serum transaminase activities (AST and ALT). Moreover, PYR exposure remarkably enhanced the expressions of hsp70 and hsp90, decreased the levels of antioxidant enzymes and biomarkers and promoted the reactive oxygen species (H2O2 and O2‐) and MDA contents in carp hepatopancreas. PYR exposure also upregulated apoptosis-related genes (bax, apaf-1, caspase-3 and caspase-9) and reduced anti-apoptosis gene bcl-2 in fish hepatopancreas. Moreover, PYR exposure altered the expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α and TGF-β) in the serum and hepatopancreas and the level of NF-κB p65 in the hepatopancreas. Further research indicated that PYR exposure markedly changed the levels of immune parameters (LYZ, C3, IgM, ACP and AKP) in the serum and/or hepatopancreas, indicating that chronic PYR exposure also has immunotoxicity on fish. Additionally, we found that PYR exposure upregulated p38 and jnk MAPK transcription levels, suggesting that MAPK may be play important role in PYR-induced apoptosis and inflammatory response in the hepatopancreas of common carp. In summary, PYR exposure induced oxidative stress, triggered apoptosis, inflammatory and immune response in common carp, which can help to elucidate the possible toxicity mechanism of PYR in fish.

Antioxidant status of fish with inflammation of the swim bladder in yearling carp

The literature data on the etiology and pathogenesis of swim bladder inflammation (SBI) in various fish species have been highlighted in the paper. The main goal of this work was to analyze the impact of the disease on the physiological status of the body of the yearling carp, the state of the antioxidant defense system, and the content of lipid peroxidation products (LPP). The yearling Liubyn scaly carps, with an average weight of 40 g, which were grown in the ponds of the Rivne fish and reclamation station, were selected for experimental research. During control catches and ichthyopathological examination of forty fish, inflammation of the swim bladder was detected with an intensity of 35 %. During the pathological autopsy of this yearling carp, thickening of the walls of the swim bladder with purulent exudate, atrophy of the posterior lobe, and hyperemia of internal organs was found. Data on the content of lipid peroxidation products (LPP) and the state of the antioxidant system (AOS) in the cells of the hepatopancreas and skeletal muscles of this year's carp with SPM have been presented. It was determined that in the hepatopancreas of fish with the swim bladder inflammation, primary and secondary LPP products accumulate, and the activity of AOS enzymes decreases. The increase of diene conjugates in the hepatopancreas of the diseased fish was revealed by 11.8 % compared to the control group, and the content of TBC-active products by 29.8 %. The level of SOD activity is 13.5 % lower in the fish affected by SMP than in the control group. Catalase activity in the hepatopancreas of the diseased fish increases by 11.7 % compared to the control group. There was a 45.5 % decrease in superoxide dismutase activity in the skeletal muscles of fish affected by SBI and a significant increase in the level of catalase (Р &lt; 0.01) compared to the control group. Pathogens that cause diseases of the swim bladder cause also have an inhibitory effect on the activity of enzymes of the antioxidant system, and the content of products of lipid peroxidation increases.

Histological changes in fish hepatopancreas and kidney as indicators of environmental quality in tropical bays

Histological changes in fish hepatopancreas and kidney as indicators of environmental quality in tropical bays

Effects of dietary protein levels on growth performance, carcass composition, nutrient digestibility and digestive enzyme activity of the critically endangered peninsular carp,Hypselobarbus pulchellus(Day, 1870) fingerlings

The dietary protein requirement of the peninsular carp, Hypselobarbus pulchellus was investigated through a feeding trial conducted in aerated plastic tanks (50 L) with five isocaloric diets formulated to contain crude protein levels ranging from 20 to 40% (CP20, CP25, CP30, CP35 and CP40) using pure ingredients with casein and gelatin as the protein sources. Fingerlings (mean wt. 4.71 g) of H. pulchellus were fed at 5% of the biomass for a period of 60 days. The growth parameters increased with dietary protein level up to 35% followed by a decrease with CP40 diet. Lowest (p < 0.05) food conversion ratio was recorded with 35% protein diet. Protein efficiency ratio values were inversely proportional to the dietary protein level. The condition factor ranged from 0.94 to1.07 with no difference among the treatments. No difference (p > 0.05) was recorded in fish survival. Proximate composition analysis of fish carcass indicated no difference (p > 0.05) in moisture, fat and ash contents. Crude protein content on the other hand, showed values increasing with dietary protein level up to 35%, beyond which (CP40), it stagnated. Apparent digestibility coefficient for protein also increased gradually with the dietary protein level with a peak under CP35 and then decreased at CP40. Fat digestibility values, on the other hand, were similar (p > 0.05) for all diets. Analysis of the activity of digestive enzymes indicated highest activity of trypsin and total protease in both intestine and hepatopancreas of fish fed 35% crude protein diet. The second- order polynomial regression analysis for weight gain rate and specific growth rate indicated a dietary protein requirement between 31.80 and 32.76% for the fingerlings of H. pulchellus. This information on protein requirement would be useful in developing species specific feed for this critically endangered peninsular carp.

Effects of Dietary Bacillus velezensis LSG2-5 on Growth, Immunity, Antioxidant Capacity, and Disease Resistance of Amur minnow (Rhynchocypris lagowskii Dybowski)

The study was aimed at investigating the effects of Bacillus velezensis LSG2-5 isolated from host’s intestinal tract on growth performance, immune response, antioxidant capacity, and disease resistance of Amur minnow (Rhynchocypris lagowskii Dybowski). 535 fish were divided into 5 groups with 3 replicates per group. Diets containing different doses (0, 106, 107, 108, and 109 CFU/g, respectively) of B. velezensis LSG2-5 were used to feed fish ( 9.95 ± 0.05 g) for 56 days. Results showed that compared with control, weight gain rate and specific growth rate of fish were significantly increased by dietary 107-109 CFU/g B. velezensis ( p &lt; .05 ). While for the feed conversion ratio, all treatment groups were significantly decreased ( p &lt; .05 ). In serum, the contents of lysozyme and immunoglobulin M were significantly increased by dietary 106-109 CFU/g B. velezensis ( p &lt; .05 ); the activities of component 3, component 4, and alkaline phosphatase were significantly increased by dietary 108 CFU/g B. velezensis ( p &lt; .05 ). The activities of catalase, glutathione peroxidase, total antioxidant capacity, and superoxide dismutase in hepatopancreas were significantly increased by dietary 108-109 CFU/g B. velezensis ( p &lt; .05 ). The activities of catalase, glutathione, glutathione peroxidase, total antioxidant capacity, and superoxide dismutase in the intestinal tract of 108 CFU/g group were significantly increased ( p &lt; .05 ). However, malondialdehyde levels in the hepatopancreas and intestines were significantly decreased by dietary 107-108 CFU/g B. velezensis ( p &lt; .05 ). Dietary 107-109 CFU/g B. velezensis significantly upregulated catalase, glutathione peroxidase, and copper/zinc superoxide dismutase mRNA levels ( p &lt; .05 ). The levels of transforming growth factor β and interleukin-10 mRNA in the hepatopancreas of fish fed with B. velezensis of 108 CFU/g were significantly increased ( p &lt; .05 ), and these in the intestinal tract of 106-109 CFU/g groups were upregulated ( p &lt; .05 ). Feeding dietary 107-108 CFU/g B. velezensis significantly downregulated interleukin-8, interleukin-1β, and tumour necrosis factor α mRNA levels in hepatopancreas and intestines ( p &lt; .05 ). After 56 days of feeding, 225 fish ( 23.20 ± 0.59 g) were challenged with Aeromonas hydrophila (108 CFU/g), and survival rates were recorded for the next 14 days. Meanwhile, the serum immune parameters of fish were determined. Results showed that compared with control, the survival rates of the treatment groups were significantly increased ( p &lt; .05 ). Lysozyme, component 3, component 4, immunoglobulin M, acid phosphatase, and alkaline phosphatase levels in serum by dietary106-109 CFU/g B. velezensis showed significant promoting effects ( p &lt; .05 ). In conclusion, dietary 107-109 CFU/g B. velezensis boosts the growth, immunity, antioxidant capacity, and against A. hydrophila infection of Amur minnow. Regression analysis suggested that the optimal dose of B. velezensis LSG2-5 in the Amur minnow diet was 5.00 × 10 8 CFU/g.

Effects of the defattedSchizochytriumsp. on growth performance, fatty acid composition, histomorphology and antioxidant status of juvenile mirror carp (Cyprinus carpiovar.specularis)

Defatted Schizochytrium sp. (DS) is a by-product of algae oil, which is rich in docosahexaenoic acid (DHA). In this study, five DS-supplemented diets, including 0 (DS0), 30 (DS3), 60 (DS6), 90 (DS9) and 120 (DS12) g/kg, were used to evaluate the effects of dietary DS on juvenile mirror carp (Cyprinus carpio var. specularis). A total of 270 fish juvenile mirror carp (8.55 g/tail, eighteen fish per cage) were fed with five isonitrogenous and isolipidic diets for 8 weeks. The results showed that final body weight (FBW), weight gain (WG) and specific growth rate (SGR) first increased in DS6 group (p > 0.05) and then significantly decreased in DS12 group (p < 0.05). There were significantly higher crude protein (CP) and lower crude lipid (CL) levels in whole body and hepatopancreas of fish fed with DS6 and DS9 diets than those with DS0 and DS3 diets (p < 0.05). The level of DHA in the muscle, hepatopancreas and whole body was significantly increased by higher DS-supplemented diets (DS6, DS9 and DS12) than that of the control group (p < 0.05). The atherogenic index (AI) and thrombosis index (TI) in the muscle of all treatment groups were significantly lower than those of the control group, while the hypocholesterolaemic/hypercholesterolaemic fatty acid ratio (h / H) index of treatment groups was significantly higher than that of the control group (p < 0.05).The height of fore-intestinal villi of DS3 and DS6 groups was significantly higher than that in the control group (p < 0.05). Moreover, superoxide dismutase (SOD) activity of the serum and hepatopancreas in DS6, DS9 and DS12 groups was significantly higher than that in the control group (p < 0.05). Analyses based on the special growth rate and antioxidant status index revealed that the suitable DS range was 4.18%–6.00% (41.08–60 g/kg), which could improve the growth performance and health status of mirror carp.

Effects of calcein on the levels of antioxidant enzymes and lipid peroxidation in juvenile silver carp, Hypophthalmichthys molitrix

Standard single-exposure of calcein (CAL) was conducted on juvenile silver carp, Hypophthalmichthys molitrix, to examine its effects on antioxidant enzyme levels and lipid peroxidation. Juveniles were exposed to different concentrations of CAL solutions (0, 100, 300, 500 and 700 mg/L) for different immersion periods (12, 24, 48, 72 and 96 hr). Increased glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase and alkaline phosphatases activities were assumed to be due to CAL-induced hepatic damage, probably because of the high potential of CAL to accumulate in fish hepatopancreas. Higher CAL concentrations (>300 mg/L) and prolonged immersion periods (>48 hr) could lead to greater toxicity in juvenile silver carp and, to a certain degree, damage the gills and hepatopancreas. The antioxidant responses in the gills and hepatopancreas result in successful elimination of the excess CAL-induced reactive oxygen species for CAL exposure ≤24 hr. Our results confirmed that the toxic effects of CAL on antioxidant enzyme levels and lipid peroxidation in juvenile silver carp depended on both CAL concentrations and duration of exposure. Moreover, concentration of CAL solutions and the immersion period should be, respectively, restricted to ≤300 mg/L and ≤24 hr, when CAL is used for immersion marking juvenile silver carp.

Condensed tannins enhanced antioxidant capacity and hypoxic stress survivability but not growth performance and fatty acid profile of juvenile Japanese seabass (Lateolabrax japonicus)

Condensed tannins (CT) have been shown a promising alternative to antibiotics for livestock, but little information is available about the effect of purified CT on the growth and health of fish. A 56-day feeding trial with 640 juvenile Japanese seabass (Lateolabrax japonicus) was conducted to assess the effects of CT on the growth performance, fatty acid composition, antioxidant capacity and hypoxic stress of L. japonicus. Four diets were formulated to contain 0 (CT0), 100 (CT100), 200 (CT200) and 400 (CT400) mg/kg CT isolated from grape seed, quadruplicate groups of 40 fish with initial body weight of 10.1 ± 0.11 g were fed to apparent satiation two times daily. Fish were dissected at the end of experiment to evaluate the somatic indexes. Blood samples were collected to analyze serum metabolites, antioxidant enzymes and non-specific immune indices. Muscle and hepatopancreas were sampled to determine fatty acid composition. At the end of the feeding trail, 15 fish from each tank were suffered with a 10-hr hypoxic stress. Blood and hepatopancreas of the suffered fish were collected to analyze antioxidant enzymes, and hepatic mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), catalase (CAT) and superoxide dismutase (SOD) were analyzed. Results indicated that growth performance, whole body compositions, serum biochemical parameters, and fatty acid profile in muscle and hepatopancreas of fish were not affected by dietary treatments. Intraperitoneal fat ratio of the fish was linearly decreased (P < 0.01) as the dietary CT increasing from 0 to 400 mg/kg. Serum total antioxidant capacity (TAOC) and CAT were linearly increased (P < 0.01), but tumor necrosis factor was linearly decreased (P < 0.05) and IL-6 was linearly and quadratically decreased (P < 0.001) with increasing CT. There was a linear increase (P < 0.05) in hepatic TAOC and anti-superoxide anion with increased dietary CT. Hepatic CAT was quadratically increased (P < 0.01), and GSH-Px and SOD were linearly and quadratically decreased (P < 0.05) with increasing CT. Cumulative mortality rate (CMR) after 10 h of hypoxic stress and serum MDA were linearly and quadratically decreased (P < 0.001), whereas serum CAT and GSH-Px were linearly increased (P < 0.01) and TAOC was linearly and quadratically increased (P < 0.05) with increasing dietary CT. Hepatic CAT and SOD after 10 h of hypoxic stress were linearly increased (P < 0.05) with CT increasing. The Nrf2 and HO-1 mRNA levels were up-regulated (P < 0.05) with increasing dietary CT, and CAT and SOD mRNA levels were up-regulated (P < 0.05) in CT400 than CT0-CT200. In conclusion, dietary CT up to 400 mg/kg can not only improve the antioxidant status of L. japonicus without affecting growth performance, but also reduce the CMR under hypoxic stress by activating Nrf2 signaling pathway.

Seasonal variation of microcystins and their accumulation in fish in two large shallow lakes of China.

Bioaccumulation of microcystins (MCs) has been widely observed in aquatic vertebrates and invertebrates, but its seasonal and specific variations remain unclear. In the present study, dissolved MCs in water, algal cell-bound MCs and muscle tissue MCs of nine fish species were investigated monthly in two of the largest shallow lakes in China: Lake Taihu and Lake Chaohu. The fish species were grouped as carnivorous, planktivorous, and omnivorous fish. Seasonal variations in dissolved and algal cell-bound MCs in water and MCs contents of fish hepatopancreas and muscle were investigated in the two lakes from 2009 to 2010. Dissolved MCs in water ranged from 0.35 to 2.56 µg l-1 in Lake Taihu and 0.16 to 2.45 µg l-1 in Lake Chaohu, and showed seasonally a unimodal distribution. Algal cell-bound MCs also showed a similar seasonal variation in both lakes, but dissolved MCs in water peaked about one month later than algal cell-bound MCs. The MCs content in the Fish muscle was higher MCs from October to December than in the other months. For most of the fish species, it exceeded the tolerable daily intake value established by the WHO. The averaged MCs content in the muscle of carnivorous, planktivorous, omnivorous fish was 48.2, 28.7 and 37.8 μg kg-1 in Lake Taihu, respectively, and 27.8, 18.6 and 20.4 μg kg-1 in Lake Chaohu. It was significantly higher in carnivorous fish than in planktivorous and omnivorous fish, indicating that carnivorous fish has a higher exposure risk to the local people when consuming the harvested fish. The average ratio of hepatopancreas to muscle MCs contents was 13.0, 25.2, 13.8 for carnivorous, planktivorous, omnivorous fishes in Lake Taihu, respectively, and 18.0, 24.9, 14.8 in Lake Chaohu. These ratio for planktivorous fish almost doubled that for carnivorous and omnivorous fish. High correlation of MC content in carnivorous, omnivorous and planktivorous fish indicates that MCs can be delivered along trophic levels in the food chains.

AMP-activated protein kinase in the grass carp Ctenopharyngodon idellus: Molecular characterization, tissue distribution and mRNA expression in response to overwinter starvation stress.

Adenosine monophosphate-activated protein kinase (AMPK) is the main energy sensor in mammals, but limited information is available regarding its role as an energy sensor in nutrient-restricted fish particularly in period of overwinter starvation. The present study aimed to investigate the role of AMPK in the grass carp Ctenopharyngodon idellus through characterization of AMPK full-length cDNAs and the measurement of transcriptional activity in response to overwinter starvation. AMPK is a heterotrimeric serine/threonine kinase that consists of a catalytic alpha (α) subunit complexed with two regulatory subunits, beta (β) and gamma (γ). In our study, we identified nine isoforms of the AMPK family in grass carp and obtained their complete coding sequences (CDS). In the grass carp, the α subunit is encoded by two isoforms (α1 and α2). The β and γ subunits are encoded by three (β1a, β1b, β2) and four isoforms (γ1, γ2a, γ2b, γ3), respectively. AMPK isoforms in grass carp possess structural features similar to mammalian AMPK and exhibit a high degree of homology with other fish and vertebrate AMPK sequences. The mRNA of nine grass carp AMPK isoforms were found to be expressed in a wide range of tissues in vivo, but the abundance of each AMPK mRNA demonstrated a tissue-dependent expression pattern, indicating that they might be key complexes playing the role of energy metabolism sensors during overwinter starvation conditions. Compared to expression levels in control fish (week 0), the expression of various AMPK isoforms significantly increased in the hepatopancreas of fish exposed to 1week or more of overwinter starvation conditions as follows: week 1 (AMPK α1 and AMPK α2), week8 (AMPK β1b and AMPK γ2b), week 12 (AMPK β2 and AMPK γ1), and week 16 (AMPK β1a, AMPK γ2a, and AMPK γ3). Additionally, compared to expression levels in control fish (week 0), the expression of various AMPK isoforms significantly increased in the adipose tissue of fish exposed to 1week or more of overwinter starvation conditions as follows: week 1(AMPK β1a and AMPK β1b), week 4 (AMPK α1, AMPK α2, AMPK γ1, AMPK γ2b and AMPK γ3), and week 8 (AMPK β2 and AMPK γ2a). Further in vitro analysis revealed that the mRNA levels of AMPK isoforms in hepatocytes (AMPK α1, AMPK α2, AMPK β1a, AMPK β1b, AMPK β2, AMPK γ2b and AMPK γ3) and adipocytes (AMPK γ2a, AMPK γ2b and AMPK γ3) changed significantly with in the first 24h of exposure to the overwinter starvation conditions. These findings confirm that nine AMPK subunits are present in grass carp and that all encode proteins with conserved functional domains. The nine AMPK subunits are all regulated at the transcriptional levels to manage excess energy expenditure during overwinter starvation stress.

Стан системи антиоксидантного захисту у гепатопанкреасі коропів за асоційованої інфекції аеромонозу з сапролегніозом

Bacterial diseases are responsible for heavy mortality in both wild and cultured fish. Co-infections are very common in nature and occur when hosts are infected by two or more different pathogens either by simultaneous or secondary infections so that two or more infectious agents are active together in the same host. Associative infections pose a significant threat to fish farming, so it is necessary to develop effective means of prevention and treatment of these infections; it is advisable to study in detail their impact on various fish. The aim of the study was to determine the intensity of lipid peroxidation processes and the activity of the antioxidant defense system in the body of carp suffering from aeromonosis and the associated infection of aeromonosis with saprolegniosis. The research was conducted at the Lviv Research Station of the Institute of Fisheries of NAAS. There were three groups of fish, 5 in each. The control group consisted of clinically healthy fish, the first experimental group (D1) – carps affected by Aeromonas hydrophila infection, the second experimental group (D2), which consisted of carps affected by associative Aeromonas hydrophila infection with Saprolegnia Sp. The results of studies have shown that carp with associative infection ‒ of Aeromonas hydrophila infection with Saprolegnia Sp. leads to the activation of lipid peroxidation processes, especially the primary product of LPO. Thus, in the hepatopancreas of fish there was an increase of 1.4 (p &lt;0.05) in the reasonable content of diene conjugates and there was a tendency to increase the content of TBA-active products. At the same time, the inhibitory effect of pathogenic factors of this disease on the activity of the enzymatic link of the antioxidant defense system was stated. In particular, carp patients with associative infection ‒ of Aeromonas hydrophila infection with Saprolegnia Sp. had higher catalase and superoxide dismutase activity, respectively, 1.3 (p &lt;0.05) and 2.3 (p &lt;0.01) times. The results of experimental studies made it possible to expand and deepen the mechanisms of the pathogenesis of the co-infection of Aeromonas hydrophila infection with Saprolegnia Sp. and to use the data to develop effective treatments.

Effects of dietary lipid levels on growth, fatty acid composition, antioxidant status and lipid metabolism in juvenileOnychostoma macrolepis

Five diets of different lipid levels, 3%, 6%, 9%, 12% and 15% (L3, L6, L9, L12 and L15), were designed and fed to juvenile Onychostoma macrolepis for 8 weeks. The juvenile O. macrolepis grew better at L9 than at L3, L6 and L15 (p < .05). The viscera and hepatopancreas indexes increased as the dietary lipid levels increased. There appeared lower serum TG and HDL levels at lipid levels of 3.01%–9.01% (p < .05). Hepatic histology showed that the fish fed on L15 diet had more hepatic lipid droplets than those fed on the other diets. Fish fed on L9 diet showed increases in superoxide dismutase, catalase and glutathione peroxidase activities but decreases in malondialdehyde content in hepatopancreas (p < .05). The principle component analysis of fatty acid showed that n-3 LC-PUFA was mostly enriched in the fillet. There were lower transcript levels of FAS, ACC1 and SREBP1 found in the hepatopancreas of fish with increased dietary lipid levels, whereas CPT-1, PPARα and ATGL expressions were elevated (p < .05). These results suggested that diets with a proper dietary lipid level of 9.01%–11.95% (optimum 9.68% was based on the specific growth rate) could improve the growth performance and health status of juvenile O. macrolepis.

Effects of bioactive substance from turmeric on growth, skin mucosal immunity and antioxidant factors in common carp, Cyprinus carpio

Present study evaluated the effects of curcumin, the principal curcuminoid of turmeric, on Cyprinus carpio growth, skin mucosal immune parameters, immune-related gene expression, and susceptibility to pathogen challenge. Diets containing four various concentrations of curcumin (g Kg−1): 0 g [basal diet], 5 g [T5], 10 g [T10], and 15 g [T15] were fed to the carp (average weight: 16.37 g) for 8 weeks. Growth parameters were analysed at 4 and 8 weeks post-feeding. Skin mucosal immune responses and expression were examined in 8 weeks post-feeding. Growth performance was significantly higher in T10 and T15, with final weight gain of 102.26 ± 2.31 g and specific growth rate of 3.24 ± 0.37, respectively. The lowest feed conversion ratio (2.35 ± 0.16) was recorded in T15 than in the control (P < 0.05). Among the skin mucosal immune parameters examined, lysozyme (36.8 ± 4.03 U mL−1), total immunoglobulin (6.74 ± 0.5 mg mL−1), protein level (18.7 ± 1.62 mg mL−1), alkaline phosphatase (96.37 ± 6.3 IU L−1), and protease activity (9.47 ± 0.82%) were significantly higher in T15, while the peroxidase activity was higher in T10 (10.24 ± 0.9 U mg−1 protein). Further, lysozyme, superoxide dismutase (SOD) and catalase (CAT) activities were measured in serum and found to be higher in T10 or T15 than in the control (P < 0.05). However, malondialdehyde level decreased significantly in T10 and T15. Furthermore, antioxidant genes (SOD, CAT, nuclear factor erythroid 2-related factor 2) and anti-inflammatory cytokine Interleukin-10 were upregulated in the head kidney, intestine, and hepatopancreas of fish in T10 and T15. Conversely, expression of pro-inflammatory cytokines (IL-1β, tumour necrosis factor-alpha), signalling molecule NF-κBp65 were down-regulated in the tested tissues of T10 and T15. Expression of Toll-like receptor 22 (TLR22) was down regulated in head-kidney and intestine of T15. Fish from T15 exhibited significantly higher relative post-challenge survival (69.70%) against Aeromonas hydrophila challenge. Results of the present study suggest that dietary supplements of curcumin at 15 g Kg−1can significantly improve the growth performance, skin mucosal and serum antioxidant parameters, and strengthen the immunity of C. carpio. Therefore, curcumin represents a promising food additive for carps in aquaculture.