Search

Yinchenhao Decoction (YD), a Chinese herbal medicine, has been traditionally used for treatment of metabolic liver diseases. A 10-week feeding trail was carried out to examine the effects of YD supplementation in a high carbohydrate diet (HCD) on liver histopathology, immune response, disease resistance, and expression of genes associated with endoplasmic reticulum stress, autophagy, apoptosis, necroptosis and inflammation in juvenile largemouth. A diet containing 9% carbohydrate was used as a low carbohydrate diet (LCD), and a HCD was formulated to contain 18% carbohydrate and supplemented with 0, 0.5, 1, 2 or 4% YD (HCD, HCD+0.5YD, HCD+1YD, HCD+2YD and HCD+4YD). Triplicate groups of fish (5.6 ± 0.2 g) were feed the test diets to visual satiety for 10 weeks. The highest survival rate after Nocardia seriolae challenge was recorded for the HCD+4YD group. YD application led to reduced ACP, AKP, AST and ALT activities. HCD-induced cells swelling, ruptured cell membrane, migrated nuclei and increasing inflammatory cells in hepatocytes were mitigated by YD addition. Moreover, YD decreased the expressions of pro-inflammation genes (TNF-α, IL-1β, IL-8, hepcidin1, NF-κB, COX2, CD80 and CD83) and increased the mRNA levels of anti-inflammation genes (IL-10 and IKBα). The mode of liver cell death was preferably changed to programed apoptosis rather than uncontrolled necroptosis by application of YD in HCD. Furthermore, the expression of UPR genes (IRE1, Eif2α, ATF6, XBP1 and GRP78/Bip) and autophagy genes (LC3-2, BNIP3 and P62) was increased by YD supplementation. In summary, our results demonstrated that YD addition in HCD enhances UPR, autophagy and programed apoptosis maintaining the homeostasis, and decreases uncontrolled necroptosis and inflammation, ultimately leading to improved immune response in largemouth bass.

This study assessed the effects of feed carbohydrate content on intestinal physical barrier and immunity in juvenile largemouth bass (Micropterus salmoides). Triplicate groups of juvenile fish (4.1 ± 0.2 g) were fed low (LCD, 7%), medium (MCD, 12%) and high (HCD, 17%) carbohydrate diets for eight weeks. Gut histology revealed the slight infiltration of inflammatory cells and moderate loss of mucous membrane layer in HCD group. Expression of ZO1, occluding, and claudin7 genes and epidermal growth factor receptor (EGFR) gene were significantly decreased in HCD group indicating the impairment of tight junction and epithelial cell regeneration. The results showed the significant (P 0.05) reduction of antioxidant capacity in HCD group compared to LCD. Furthermore, expression of intestinal ERS-related genes such as IRE1, Eif2α, GRP78, CHOPα and CHOPβ in HCD group was significantly higher than the LCD group. In addition, HCD induced the up-regulated expression of inflammatory (IL-8, IL-1β, TNFα and COX2) and apoptosis (TRAF2, bax, casepase3, caspase8 and casepase9) related genes in fish intestine. The data generated in this study clearly demonstrated that HCD induced ERS and oxidative stress, which promoted intestinal inflammation and apoptosis in juvenile largemouth bass.

This study evaluated the effects of dietary methionine level and rearing water temperature on growth, antioxidant capacity, methionine metabolism, and hepatocyte autophagy in spotted seabass (Lateolabrax maculatus). A factorial design was used with six methionine levels [0.64, 0.85, 1.11, 1.33, 1.58, and 1.76%] and two temperatures [moderate temperature (MT): 27 ℃, and high temperature (HT): 33 ℃]. The results revealed the significant effects of both dietary methionine level and water temperature on weight gain (WG) and feed efficiency (FE), and their interaction effect was found on WG (P 0.05). In both water temperatures tested, fish WG increased with increasing methionine level up to 1.11% and decreased thereafter. The groups of fish reared at MT exhibited dramatically higher WG and FE than those kept at HT while an opposite trend was observed for feed intake. Liver antioxidant indices including reduced glutathione and malondialdehyde (MDA) concentrations, and catalase and superoxide dismutase (SOD) activities remarkably increased in the HT group compared to the MT group. Moreover, the lowest MDA concentration and the highest SOD activity were recorded at methionine levels between 1.11% and 0.85%, respectively, regardless of water temperatures. Expression of methionine metabolism-related key enzyme genes (mat2b, cbs, ms, and bhmt) in the liver was increased at moderate methionine levels, and higher expression levels were detected at MT compared to HT with the exception of ms gene relative expression. Relative expression of hepatocyte autophagy-related genes (pink1, atg5, mul1, foxo3) and hsp70 was upregulated by increasing methionine level up to a certain level and decreased thereafter and increasing water temperature led to significantly enhanced expression of hsp70. In summary, HT induced heat stress and reduced fish growth, and an appropriate dietary methionine level improved the antioxidant capacity and stress resistance of fish. A second-order polynomial regression analysis based on the WG suggested that the optimal dietary methionine level for maximum growth of spotted seabass is 1.22% of the diet at 27 ℃ and 1.26% of the diet at 33 ℃, then 1.37 g and 1.68 g dietary methionine intake is required for 100 g weight gain at 27 ℃ or 33 ℃, respectively.

This study examined the effect of konjac glucomannan (KGM) supplementation in diets with different lipid levels on growth, antioxidant capacity, hepatic lipid metabolism and inflammatory response in juvenile pompano (Trachinotus ovatus). Triplicate groups of fish (12.07 ± 0.21 g) were fed eight experimental diets containing two lipid levels of 9% (basal-fat diet, BFD) and 18% (high-fat diet, HFD), and four levels of KGM (0, 0.5, 1 and 2%) for 60 days. Pompano fed HFD exhibited markedly lower growth and feed efficiency than fish fed BFD, and KGM supplementation, particularly at 1% inclusion, significantly improved growth performance and feed efficiency in fish fed both BFD and HFD. In addition, Pompano fed HFD showed higher whole-body lipid and lower protein contents than fish fed BFD. Irrespective of dietary lipid level, whole body, dorsal and ventral muscle were reduced by dietary KGM supplementation up to 1% while the opposite was found for whole body protein content. Dietary KGM also significantly reduced the HSI, liver lipid contents, as well as lipid droplets in the liver. Supplementation of KGM to both BFD and HFD significantly reduced serum total cholesterol, triglyceride, low-density lipoprotein cholesterol and free fatty acids levels. Furthermore, irrespective of dietary lipid level, increasing dietary KGM supplementation enhanced serum IgM level, lysozyme and alkaline phosphatase activities, and reduced serum alanine aminotransferase and aspartate aminotransferase activities. Dietary KGM also increased liver total antioxidant capacity, superoxide dismutase and catalase activities, and decreased malondialdehyde concentration in fish fed both HFD and BFD. Dietary KGM significantly increased serum glutathione peroxidase, superoxide dismutase and catalase activities and reduced malondialdehyde concentrations in fish fed BFD, and enhanced serum total antioxidant capacity and glutathione peroxidase activity in fish fed HFD. Supplementation of KGM increased the expression of genes associated with lipid catabolism (pparα, cpt1, hsl) and lipid transport (fabp1, apoB100 and cd36), and decreased the expression of lipid anabolism related genes (srebp1, pparγ, fas and acc). Moreover, the expression of pro-inflammatory cytokines including tumor necrosis factor α and interleukin-8 were down-regulated, while expression of the anti-inflammatory cytokine transforming growth factor β1 was increased by KGM supplementation. In conclusion, supplementation of KGM at 1% of diet improved growth, feed efficiency, antioxidant capacity, hepatic lipid metabolism and inflammatory responses in juvenile pompano, and can mitigate excessive deposition of lipid in tissues of farmed fish., This research was supported by the China Agricultural Research System (CARS-47), Guangdong Agriculture Research System (2021KJ150), Natural Science Foundation of Guangdong Province (2020A1515011252), Innovation and Strong School Projects in Guangdong Province (2020ZDZXlO14) and Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML2019ZD0606).

Two studies were carried out to (a) characterize the gastrointestinal (GI) tract of bullfrog Rana (Lithobates) catesbeiana and (b) to evaluate the effects of total replacement of fish meal (FM) with soybean meal (SBM) on GI tract health. For characterization of the GI tract, oesophagus, stomach and intestine sections were sampled from 20 bullfrogs (80 g) fed a FM‐based diet. The results revealed that the GI tract of bullfrog is consisted of four tissue layers including mucosa, submucosa, muscularis and serosa, and that the intestine could be divided into duodenum, jejunum, ileum and rectum. Furthermore, the abundance and length of mucosal folds suggested that jejunum is the primary site of digestion and absorption of nutrients. In the second study, a diet containing 44% fish meal (FM) was formulated and used as a FM‐based diet, and a SBM‐based diet was prepared by entire substitution of FM with SBM. Sixty bullfrogs (35 ± 1 g) were divided into three replicates of the two groups and were fed the test diets to apparent satiation twice daily for 8 weeks. The changes in pH and morphology of GI tract in response to the shift in dietary protein source were evaluated. The results showed the enhancement of pH values in GI tract of the SBM group excluding cardia, jejunum and rectum. Also, SBM diet triggered significant decreases in the number, height and width of mucosal folds, while an opposite trend was observed for thickness of lamina propria. Moreover, the entire replacement of FM with SBM led to the separation of submucosa from muscularis and incidence of lesion in mucous epithelium. The findings in this study showed that jejunum is the main site of nutrients digestion and absorption. Also, it was demonstrated that entire replacement of FM with SBM adversely influenced the GI tract health in bullfrog.

This study evaluated the effects of replacing fish meal (FM) with defatted silkworm pupae meal (SPM) on growth, diet digestibility, antioxidant capacity, hepatopancreas histology and molting process in Pacific white shrimp (Litopenaeus vannamei). A basal diet was formulated to contain 24% FM, then 25, 50, 75 or 100% of FM was substituted with SPM referred to as FM, SPM25, SPM50, SPM75 and SPM100 diets, respectively. Quadruplicate groups (36 shrimp per replicate) of shrimp (0.2 ± 0.02 g) were fed the test diets to apparent satiation three times daily for eight weeks. No significant difference (P > .05) in growth performance could be found among FM and SPM groups. Apparent digestibility coefficients of dry matter, gross energy and phosphorous were significantly improved by SPM inclusion. Serum antioxidant parameters including total antioxidant capacity and malondialdehyde concentration were beneficially influenced by SMP inclusion. Higher number of B-cells and lower number of E-cells were detected in hepatopancreatic tubules of SPM100 group compared to the other groups. Moreover, total replacement of FM triggered separation of basal membrane and greater interstitial spaces between the hepatopancreatic tubules. Molting time significantly decreased when FM was entirely replaced with SPM. Also, chitin deacetylase activity was enhanced in SPM100 group, but β-N-Acetyl- d -glucosaminidase activity, and expression of ecdysteroid receptor and retinoid X receptor remained unchanged. To conclude, the entire replacement of FM with SPM did not influence shrimp growth, and its beneficial impacts were found on diet digestibility, antioxidant capacity and molting time. However, the substitution level is recommended to be restricted to 75% as total replacement led to shrinkage of hepatopancreatic cells.

Many metabolic diseases in fish are often associated with lowered mitochondrial fatty acid β-oxidation (FAO). However, the physiological role of mitochondrial FAO in lipid metabolism has not been verified in many carnivorous fish species, for example in largemouth bass (Micropterus salmonids). In the present study, a specific mitochondrial FAO inhibitor, mildronate (MD), was used to investigate the effects of impaired mitochondrial FAO on growth performance, health status, and lipid metabolism of largemouth bass. The results showed that the dietary MD treatment significantly suppressed growth performance and caused heavy lipid accumulation, especially neutral lipid, in the liver. The MD-treated fish exhibited lower monounsaturated fatty acid and higher long-chain polyunsaturated fatty acids in the muscle. The MD treatment downregulated the gene expressions in lipolysis and lipogenesis, as well as the expressions of the genes and some key proteins in FAO without enhancing peroxisomal FAO. Additionally, the MD-treated fish had lower serum aspartate aminotransferase activity and lower pro-inflammation- and apoptosis-related genes in the liver. Taken together, MD treatment markedly induced lipid accumulation via depressing lipid catabolism. Our findings reveal the pivotal roles of mitochondrial FAO in maintaining health and lipid homeostasis in largemouth bass and could be hopeful in understanding metabolic diseases in farmed carnivorous fish.

Background: Promising physicochemical characteristics of nanoparticles (NPs) have encouraged their increasing synthesis and application in various industries which is accompanied with their leakage to the environment with inevitable effects on non-target animals including fish. Accordingly, developing strategies to protect fish against NPs contamination has gained attention. The aims of this study were to (a) explore the effects of feed born silver nanoparticles (AgNPs) in common carp (Cyprinus carpio), and (b) to examine whether dietary curcumin supplementation can ameliorate the impacts of AgNPs on growth, hemato-biochemical parameters, digestive enzymes activity and organ histology. Methods: Nine experimental diets were prepared with three different levels of AgNPs (0, 0.05 and 0.15 g/kg) and curcumin (0, 0.75 and 1.5 g/kg) and fed to triplicate groups of common carp (4.82 ± 0.41 g) for 60 days. Results: The results showed that AgNPs significantly (P < 0.05) reduces growth performance and enhances feed conversion ratio in a dose dependent manner. Supplementing 0.75 g/kg curcumin at lower AgNPs level improved growth rate while its inclusion at higher AgNPs level further hampered fish growth. A similar trend was observed for survival rate. The highest hematocrit and hemoglobin concentrations and white blood cells count were recorded in the group received 0.75 g/kg curcumin, and inclusion of the same dose of curcumin in the diet containing 0.05 g/kg AgNPs retrieved the reduction of these parameters. Serum aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities, and glucose, cholesterol and triglyceride concentrations were enhanced by increasing AgNPs level, and curcumin inclusion particularly at lower level of AgNPs significantly decreased their values. Activity of digestive enzymes including alkaline protease and lipase were progressively decreased by increasing AgNPs level and significant improvements were found by curcumin application at lower AgNPs level. In addition, severe pathological changes in liver and intestine were observed at high concentrations of AgNPs and curcumin. Conclusions: The findings in this study demonstrated that dietary supplementation of curcumin at lower dose of AgNPs can restrain the toxic effects, however, its inclusion at higher dose of AgNPs exacerbated the negative impacts.

Two experiments were carried out to examine the impacts of hydroxytyrosol (HT) on lipid metabolism and mitochondrial function in Megalobrama amblycephala. Triplicate groups of fish were fed four test diets: (1) low-fat diet (LFD, 5% fat), (2) high-fat diet (HFD, 15% fat), (3) LFD + 100 mg/kg HT (LFD + HT), and (4) HFD + 100 mg/kg HT (HFD + HT) (in vivo). Hepatocytes from the same batch were exposed to three media including L-15 medium (L15), oleic acid (OA) medium [L15 + 400 μM OA], and OA + HT medium [L15 + 400 μM OA + 10 μM HT] to explore the roles of HT in mitochondrial function (in vitro). Fish fed HFD had excessive fat deposition in the liver, and HT inclusion in the HFD decreased hepatic fat deposition. Transmission electron microscopy revealed that the HFD triggers loss of cristae and metrical density and hydropic changes in mitochondria and that HT supplementation attenuates the ultrastructural alterations of mitochondria. The in vitro test showed that HT decreases fat deposition in hepatocytes, suppresses the reactive oxygen species formation, and facilitates the expression of phospho-AMPK protein and the genes involved in mitochondria biogenesis (PGC-1, NRF-1, TFAM) and autophagy (PINK1, Mul1, Atg5). These findings suggest the lipid-lowering effect of HT mediated by activation of mitochondrial biogenesis and autophagy through the AMPK pathway.

This study examined the effects of replacing fish meal (FM) with three different types of soybean meal (SM) including untreated SM, Bacillus pumillus SE5 (BP) fermented SM (BPFSM) and Pseudozyma aphidis ZR1 (PA) fermented SM (PAFSM) in diets for Japanese seabass (Lateolabrax japonicus). A basal diet was formulated using FM (FM diet), and six other diets were produced by substituting 40 or 80% of FM with SM, BPFSM or PAFSM (SM40, SM80, BPFSM40, BPFSM80, PAFSM40 and PAFSM80 diets). Each diet was fed to triplicate groups of fish (7.14 ± 0.05 g) twice daily for eight weeks. Replacing 40% of FM with SM sources did not significantly influence growth (P > 0.05), while increasing the substitution level to 80% led to reduced growth rates (P

An 8-week feeding trial was carried out to evaluate the effects of replacing fish meal (FM) with housefly (Musca domestica) maggot meal (HFMM) on growth, antioxidant capacity, digestive enzymes activity, and gut health of bullfrog Rana (Lithobates) catesbeiana. A basal experimental diet was formulated using FM and soybean meal as the major protein sources, then four other diets were produced by replacing 25, 50, 75 or 100% of FM with HFMM (FM, HFMM25, HFMM50, HFMM75 and HFMM100 diets). Each diet was fed to triplicate groups of bullfrog (34.1 ± 1.10 g) to apparent satiation twice daily. No significant linear or quadratic trends were observed between FM replacement level and growth, feed utilization and survival rate (P > 0.05). A significant negative linear trend was detected between the incremental levels of HFMM and apparent digestibility coefficients (ADCs) of dry matter, protein and lipid, while positive linear and quadratic trends were found in ADC of phosphorous (P

p38 mitogen-activated protein kinase (MAPK) is an important protein which plays a key role in regulating the innate immunity, so exploring its molecular characterization is helpful in understanding the resistance against microbial infections in cultured fish. Here, a full-length cDNA of p38 MAPK was cloned from liver of blunt snout bream (Megalobrama amblycephala) which covered 2419 bp with an open reading frame of 1086 bp encoding 361 amino acids. p38 MAPK contained the characteristic structures of Thr-Gly-Tyr (TGY) motif and substrate binding site Ala-Thr-Arg-Trp (ATRW), which are conserved in MAPK family. To investigate p38 MAPK functions, two in vivo experiments were carried out to examine its expression following ammonia exposure and bacterial challenge. Also, an in vitro experiment was conducted to assess the role of p38 MAPK in inflammation of primary hepatocytes induced by lipopolysaccharide (LPS). The results showed the ubiquitous expression of p38 MAPK in all the tested tissues with varying levels. p38 MAPK mRNA expression was significantly up-regulated by ammonia stress and Aeromonas hydrophila challenge, and altered in a time-dependent manner. Moreover, the results indicated that the inflammatory response induced by LPS in hepatocytes is p38 MAPK dependent as knockdown of p38 MAPK using siRNA technology depressed the expression of IL-1β and IL-6. The findings in this study showed that p38 MAPK has anti-stress property, and plays key role in protection against bacterial infection and inflammation in blunt snout bream.

This study aimed at achieving the molecular characterization of peroxisome proliferator-activated receptor-gamma coactivator 1&beta, (PGC-1&beta, ) and exploring its modulatory roles in mitochondria biogenesis in blunt snout bream (Megalobrama amblycephala). A full-length cDNA of PGC-1&beta, was cloned from liver which covered 3110 bp encoding 859 amino acids. The conserved motifs of PGC-1&beta, family proteins were gained by MEME software, and the phylogenetic analyses showed motif loss and rearrangement of PGC-1&beta, in fish. The function of PGC-1&beta, was evaluated through overexpression and knockdown of PGC-1&beta, in primary hepatocytes of blunt snout bream. We observed overexpression of PGC-1&beta, along with enhanced mitochondrial transcription factor A (TFAM) expression and mtDNA copies in hepatocytes, and its knockdown led to slightly reduced NRF1 expression. However, knockdown of PGC-1&beta, did not significantly influence TFAM expression or mtDNA copies. The alterations in mitochondria biogenesis were assessed following high-fat intake, and the results showed that it induces downregulation of PGC-1&beta, Furthermore, significant decreases in mitochondrial respiratory chain activities and mitochondria biogenesis were observed by high-fat intake. Our findings demonstrated that overexpression of PGC-1&beta, induces the enhancement of TFAM expression and mtDNA amount but not NRF-1. Therefore, it could be concluded that PGC-1&beta, is involved in mitochondrial biogenesis in blunt snout bream but not through PGC-1&beta, /NRF-1 pathway.

Fatty liver of cultured fish often correlates closely with poor growth and low harvest yield. Some Chinese herbs can reduce hepatic fat storage. This study aimed to examine lipid-lowering effect of berberine (BBR) in blunt snout bream (Megalobrama amblycephala). Triplicate groups of fish were fed four experimental diets: low-fat diet (LFD, 5% fat), high-fat diet (HFD, 15% fat), and HFD supplemented with 50 or 100 mg BBR/kg diet (BBR50, BBR100). After 8-week feeding, growth performance, liver histology and fat deposition, and hepatic genes expression were examined. The results showed significant reduction of growth performance and feed intake in fish fed HFD compared to those fed the LFD and BBR50 diets. Supplementing 50 mg BBR/kg to the HFD significantly improved weight gain and feed intake. Higher hepatic fat content and histological abnormalities were found in the liver of fish receiving HFD, and BBR50 and BBR100 could attenuate these abnormalities of liver. Expression of CPT I, AOX, ApoB100, ApoE, and PGC-1α genes was significantly decreased in fish fed HFD, and 50 and 100 mg/kg BBR supplementation could revert the downregulation of these genes. Also, the expression of FATP, LPL, and LDLR genes was upregulated in HFD-fed fish, and their expression was significantly decreased by 50 and 100 mg/kg BBR supplementation. In conclusion, supplementing BBR to HFD could attenuate liver fat deposition and disorders. The fat-lowering effects of BBR appear to be mediated by activating genes related with fatty acid oxidation and decreasing genes for fatty acid uptake.

This study investigated the effects of photoperiod duration on growth, heamatological and blood biochemical parameters, and antioxidant capacity of largemouth bass (Micropterus salmoides). Triplicate groups of juvenile fish (33.22 ± 4.68 g) were kept in a recirculating aquaculture system and exposed to five different photoperiods [light/dark (L/D), h] as follows: 8L:16D; 12L:12D; 16L:8D; 20L:4D and 24L:0D. All the fish were fed a commercial diet at a fixed ratio of 1% body mass with daily inspection of the consumed feed. The experiment lasted 16 weeks and fish growth was monitored at 4-week intervals. The results revealed the significant effect of photoperiod duration on growth rate and feed utilization. The constant light exposure (24L:0D) benefited weight gain (WG) only during the first four weeks while thereafter negative impacts were noticed. At the end of the feeding trial, the highest WG and specific growth rate were obtained in the 8L:16D group which significantly differed from those of the 12L:12D and 16L:8D groups. Although fish feed intake was not influenced by photoperiod duration, better feed conversion ratio was found in the 8L:16D group. Moreover, the same group exhibited the highest hepatosomatic and gonadosomatic indices, and haemoglobin concentration. The highest plasma total protein and globulin concentrations were recorded for the 16L:8D group. Plasma glucose concentration decreased by prolongation of light duration while opposite trends were observed for plasma ammonia concentration and creatinine kinase activity. The highest alanine aminotransferase and aspartate aminotransferase activities were found in 20L:4D and 12L:12D groups, respectively. Moreover, plasma alkaline phosphatase activity significantly decreased in 12L:12D and 16L:8D groups. Longer light duration led to remarkable increase of thiobarbituric acid reactive substances (TBARS) concentration in fish liver, brain and gill indicating the incidence of oxidative stress. Likewise, boosted antioxidant responses were found in liver [glutathione (GSH) and glutathione S-transferase (GST)], brain (GST) and kidney (superoxide dismutase) as light duration extended. These findings suggest that 8 L:16D is favouring better growth, organosomatic index and antioxidant capacity of largemouth bass juveniles reared in RAS.

The trial investigated the effects of dietary supplementation with the commercial prebiotic galactooligosaccharide (1% GOS; GOS diet), the commercial probiotic Pediococcus acidilactici MA18/5 M (6.3 log CFU g− 1 PA; PA diet) and their combination as synbiotic (1% GOS and 6.3 log CFU g− 1 PA; SYN diet) on the growth, innate immunity and disease resistance of juvenile rockfish (Sebastes schlegeli). Triplicate groups of fish (18.2 ± 0.3 g) were fed one of the four diets for 8 weeks and then subjected to a standard challenge with Edwardsiella tarda by intraperitoneal injection. The results showed significant (P

The aim of this study was to evaluate the effects of substituting fish meal (FM) with soybean meal (SM) on growth performance, digestive enzymes activity, gut histology, and intestinal pro-inflammatory and transporter genes expression in Japanese seabass ( Lateolabrax japonicus ). Totally three test diets were prepared: a basal FM-based diet and two SM diets by substituting 50 or 75% of FM with SM (FM, SM50 and SM75 diets). Each diet was fed to triplicate groups of fish (6.67 ± 0.03 g) to apparent satiation twice a day for eight weeks. The results showed no significant ( P > 0.05) differences in growth performance between FM and SM50 groups while further increment of replacement level to 75% led to a significantly ( P

Fish farming seriously influences the aquatic environment because most dietary phosphorus (P) is excreted in the effluent. To increase the P utilization in fish, molecular techniques should be explored given the remarkable development of these techniques. Thus, to identify the candidate genes related to P utilization and molecular alterations following administration of a P-deficient diet in seabass Lateolabrax japonicus, we assessed the de novo pituitary, gill, intestine, liver, kidney, scales and vertebra transcriptomes, and we compared the expression of hepatic genes with three diets varying in P and Ca levels: diet I (0.4% P, 0.3% Ca), diet II (0.8% P, 0.3% Ca), and diet III (0.8% P, 3% Ca). In total, we identified 99,392 unigenes, and 37,086 (37.31%) unigenes were annotated. The results showed that 48 unigenes were significantly (P

Effects of guanidinoacetic acid (GAA) supplementation in all-plant protein diets were evaluated on growth, antioxidant capacity and muscle energy metabolism of Rana (Lithobates) catesbeiana. Six diets were prepared: a basal fish meal diet (FM), an all soybean meal diet (SM) and four GAA-supplemented diets by adding 0.2, 0.4, 0.6 and 0.8 g GAA/kg to the SM diet (GAA2, GAA4, GAA6 and GAA8 diets). Triplicate groups of bullfrog (45 ± 0.2 g) were fed the diets to apparent satiation for 8 weeks. Total substitution of FM with SM led to significantly (p

An in-vitro study was carried out to examine the effects of yeast hydrolysate (YH) on antioxidant capacity and innate immunity of blunt snout bream (Megalobrama amblycephala) hepatocytes. Fish primary hepatocytes were seeded at a density of 3 × 105 cells mL−1 in 6-well tissue culture plates and treated with two different media including: 1) DMEM/F12 medium (control), and 2) YH medium [DMEM/F12 + 0.1 g L−1 YH]. After incubation for 24 h, the culture medium and primary hepatocytes were collected for subsequent analyses. The results showed no significant (P > 0.05) effect of YH on aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) activities and urea nitrogen (UN) concentration in the conditioned medium. However, significantly (P

This study evaluated the effects of first feeding regime on growth performance, survival rate, and development of digestive organs (intestine, liver and pancreas) in pikeperch (Sander lucioperca) larvae. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8-13 DPH rotifers/14-17 DPH Artemia; (C) 8-10 DPH rotifers/11-17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Growth performance, survival rate and histological features of intestine, liver and pancreas were assessed at 11, 14 and 17 DPH to examine the effects of feeding regime. The groups fed rotifers for initial 3 days followed by feeding on Artemia (group D) (53 +/- 5.43%) and combination of rotifers and Artemia (group E) (68 +/- 5.51%), respectively, for the following 9 days showed significantly (P lt .05) higher survival rates than the other groups (36-50%). The group fed merely on rotifers (groups A) exhibited significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding. Moreover, the highest total length (8.57 +/- 0.57 mm), myotome height (0.75 +/- 0.09 mm) and eye diameter (0.58 +/- 0.05 mm) were obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Significant differences among groups were found in morphometric parameters in the anterior intestine and liver. The results of histological examination of the liver, intestine and pancreas did not show any obvious pathological changes in all groups. In conclusion, feeding with rotifers from 5 to 8 DPH and afterwards with Artemia could be suggested as an economical feeding regime for first feeding of pikeperch larvae as comparable survival and growth to co-feeding with rotifers and Artemia were achieved.

This study aimed at achieving the molecular characterization of peroxisome proliferator-activated receptor-gamma coactivator 1β (PGC-1β) and exploring its modulatory roles in mitochondria biogenesis in blunt snout bream (Megalobrama amblycephala). A full-length cDNA of PGC-1β was cloned from liver which covered 3110 bp encoding 859 amino acids. The conserved motifs of PGC-1β family proteins were gained by MEME software, and the phylogenetic analyses showed motif loss and rearrangement of PGC-1β in fish. The function of PGC-1β was evaluated through overexpression and knockdown of PGC-1β in primary hepatocytes of blunt snout bream. We observed overexpression of PGC-1β along with enhanced mitochondrial transcription factor A (TFAM) expression and mtDNA copies in hepatocytes, and its knockdown led to slightly reduced NRF1 expression. However, knockdown of PGC-1β did not significantly influence TFAM expression or mtDNA copies. The alterations in mitochondria biogenesis were assessed following high-fat intake, and the results showed that it induces downregulation of PGC-1β. Furthermore, significant decreases in mitochondrial respiratory chain activities and mitochondria biogenesis were observed by high-fat intake. Our findings demonstrated that overexpression of PGC-1β induces the enhancement of TFAM expression and mtDNA amount but not NRF-1. Therefore, it could be concluded that PGC-1β is involved in mitochondrial biogenesis in blunt snout bream but not through PGC-1β/NRF-1 pathway.

This study was carried out to investigate the effects of dietary inclusion of defatted Chlorella on growth performance, body composition, blood biochemistry, and antioxidant enzyme activity in olive flounder. Four isonitrogenous (51% crude protein) diets were formulated to contain 0 (control), 5, 10, or 15% Chlorella meal (CM) (designated as Con, CM5, CM10, and CM15, respectively) and fed to triplicate groups of fish (104.4 g) to apparent satiation twice daily for 8 wk. At the end of the feeding trial, significant enhancement (P < 0.05) in growth performance was obtained at over 10% CM compared to fish fed the control diet. No significant changes in dorsal muscle and liver proximate composition were found following CM administration. The groups fed CM-containing diets revealed significantly lower plasma cholesterol concentration than those fed the control diet. Dietary CM affected antioxidant enzyme activity; significantly higher plasma catalase activity was found in fish fed ≥10% CM and total antioxidant capacity increased in CM5 and CM10 groups compared to the control. However, plasma glutathione peroxidase and superoxide dismutase activities were not significantly influenced by dietary CM. Also, significant enhancement in 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity was found in dorsal muscle of fish fed CM15 diet compared to the control. The findings in this study showed that dietary inclusion of 10–15% CM can enhance growth performance and affect antioxidant enzyme activity and lipid metabolism in olive flounder.

The impacts of fish meal (FM) substitution with Bacillus pumillus SE5 fermented soybean meal (FSM) were investigated in spotted seabass juveniles. A diet containing 35% FM was considered as the basal diet, then 20, 40, 60 and 80% of FM was replaced with FSM (FM, FSM20, FSM40, FSM60 and FSM80 diets). The experimental diets were fed to three replicate groups of fish (14.3 ± 0.35 g) for eight weeks. The results showed linear and quadratic decrease of growth performance by increasing FM replacement level (P

The aims of this study were to investigate (a) the effects of single or multiple sperm collection with catheter, and (b) impacts of multiple sampling method (catheter or syringe) on sperm quality in pikeperch (Sander lucioperca). To compare the effects of sampling method, sperm was collected repeatedly from the same fish using catheter (n = 6) or syringe (n = 5) at 48, 52 and 56 h post-hormonal injection. For the single collection group as control, sperm was collected with catheter from 12 fish at 48 h post-injection. The results showed that multiple sperm collection with catheter does not significantly (P ˃ 0.05) influence sperm volume and density compared to single sperm collection. However, multiple collection with syringe led to drastic reduction of sperm density at 56 h post-injection. Moreover, sperm volume was influenced by post-injection time where the highest volume was obtained at 48 h post-injection. Furthermore, sperm density and osmolality of seminal plasma were significantly affected by sampling method and post-injection time where higher values were found for the samples collected with catheter at 48 h post-injection. Number of males producing milt with motile spermatozoa decreased along with multiple sperm collection. Sperm motility at 60 s post-activation was affected by the interaction of sampling method and post-injection time, and the highest value was obtained for the sperm collected with syringe at 48 h post-injection. Sperm curvilinear velocity (VCL) at 15 and 45 s post-activation was affected by sampling method and post-injection time, respectively. These findings contribute to the pikeperch hatchery practices, as multiple sperm collection could be applied during artificial reproduction if limited number of males are available.

A feeding experiment was carried out to examine the effects of total replacement of fish meal (FM) with soybean meal (SM) on growth performance and gut microbial composition in bullfrog (Lithobates catesbeianus). A basal diet containing 44% FM was used as a FM-based diet and a SM-based diet was produced by entire replacement of FM with SM. The two diets were fed to triplicate groups of bullfrog (40 ± 0.24 g, 14 bullfrogs per aquarium) to apparent satiation twice daily for 8 weeks. The results revealed the significant (P

Aquaculture jeopardizes the aquatic environment by discharge of the most dietary phosphorus (P) into the water. Reducing the dietary P level is a common approach for decreasing the P discharge but it may result in increased risk of P deficiency leading to vertebral deformities. However, the molecular mechanism of vertebral deformities is poorly understood. We assessed vertebral transcriptome and compared the genes associated with bone metabolism in Japanese seabass (Lateolabrax japonicus) fed three diets containing different P and Ca levels including: diet I (0.4% P, 0.3% Ca), diet II (0.8% P, 0.3% Ca) and diet III (0.8% P, 3% Ca). The results showed that P deficiency reduces the ossification of vertebrae and induces visible vertebral deformities. Moreover, 256 gens were up-regulated and 125 genes were down-regulated in fish fed P deficient diets. Furthermore, administration of the diet with adequate P and Ca excess (diet III) resulted in the significant enhancement in expression of 19 genes and reduced expression of 93 genes. Comparing group II with group III, expression of 109 genes was up-regulated and expression of 1369 genes was down-regulated. Gene ontology enrichment analysis revealed significant alterations in biological functions by P deficiency. In summary, these findings indicated that both dietary P shortage and Ca excess lead to reduced differentiation and proliferation of osteoblast and induce a higher activity of osteoclastogenesis, which could subsequently impair vertebral mineralization and cause skeletal deformities.

PGC1α is a transcriptional coactivator that plays key roles in mitochondrial biogenesis, so exploring its molecular characterization contributes to the understanding of mitochondrial function in cultured fish. In the present study, a full-length cDNA coding PGC1α was cloned from the liver of blunt snout bream (Megalobrama amblycephala) which covered 3741 bp with an open reading frame of 2646 bp encoding 881 amino acids. Sequence alignment and phylogenetic analysis revealed high conservation with other fish species, as well as other higher vertebrates. Comparison of the derived amino acid sequences indicates that, as with other fish, there is a proline at position 176 (RIRP) compared to a Thr in the mammalian sequences (RIRT). To investigate PGC1α function, three in vitro tests were carried out using primary hepatocytes of blunt snout bream. The effect of AMPK activity on the expression of PGC1α was determined by the culture of the hepatocytes with an activator (Metformin) or inhibitor (Compound C) of AMPK. Neither AMPK activation nor inhibition altered PGC1α expression. Knockdown of PGC1α expression in hepatocytes using small interfering RNA (si-RNA) was used to determine the role of PGC1α in mitochondrial biogenesis. No significant differences in the expression of NRF1 and TFAM, and mtDNA copy number were found between control and si-RNA groups. Also, hepatocytes were cultured with oleic acid, and the findings showed the significant reduction of mtDNA copy number in oleic acid group compared to control. Moreover, oleic acid down-regulated the expression of NRF1 and TFAM genes, while PGC1α expression remained unchanged. Our findings support the proposal that PGC1α may not play a role in mitochondrial biogenesis in blunt snout bream hepatocytes.