Background Environmental hypoxia is a common phenomenon in aquaculture,which causes gill tissue injury in fish.Glutathione(GSH)is a vital antioxidant in animal tissues,and its levels decrease under hypoxic conditions....Background Environmental hypoxia is a common phenomenon in aquaculture,which causes gill tissue injury in fish.Glutathione(GSH)is a vital antioxidant in animal tissues,and its levels decrease under hypoxic conditions.However,the effects of glutathione on fish under hypoxic stress remain poorly understood.This study aimed to investigate the impact of glutathione on gill tissue damage in fish under hypoxic stress and explore the underlying mechanisms.Methods Six experimental diets with varying glutathione concentrations.The actual glutathione levels in these diets,measured by high-performance liquid chromatography,were 0.00,145.95,291.90,437.85,583.80,and 729.75 mg/kg,respectively.Fish were fed these diets for 70 d,after which a 96-h hypoxic stress experiment was conducted.The experiment was set up with normoxic and hypoxic groups,in which the dissolved oxygen in the group was 6 mg/L,and that in the group was 1 mg/L.Results This research revealed that glutathione could enhance the growth performance and antioxidant capability of juvenile grass carp while mitigating the structural damage to gill tissues induced by hypoxia stress.Mechanistic investigations further indicated that glutathione mitigated hypoxia-induced oxidative injury in gill tissues and improved their antioxidant capacity.In addition,glutathione attenuated gill apoptosis induced by hypoxia stress.Glutathione also inhibited the initiation,nucleation,elongation,and degradation phases of autophagy,thereby attenuating hypoxia-induced gill autophagy.Moreover,glutathione was found to alleviate hypoxia-induced endoplasmic reticulum stress(ERS)in gills,a response potentially linked to the suppression of PERK,IRE1,and ATF6 signaling pathways.Finally,based on the ROS and PC contents in gill tissue,the optimum glutathione supplementation levels for juvenile grass carp under hypoxia stress were 437.10 and 495.00 mg/kg,respectively.Conclusions In conclusion,our experimental results demonstrated the effectiveness of glutathione in alleviating gill tissue damage caused by hypoxic stress.This study confirms the feasibility and effectiveness of dietary glutathione addition to alleviate hypoxic stress in fish.展开更多
Background In intensive aquaculture systems,the frequent incidence of enteritis reduces production efficiency and results in significant economic losses.Protein feeds account for 40%–60%of aquafeed expenses,and with ...Background In intensive aquaculture systems,the frequent incidence of enteritis reduces production efficiency and results in significant economic losses.Protein feeds account for 40%–60%of aquafeed expenses,and with the growth of intensive aquaculture,demand for fishmeal as a key protein source outstrips supply,driving up prices.This study investigated the therapeutic potential of reducing dietary protein levels by 3%and adding enzymatic cottonseed protein(ECP)in juvenile yellow catfish with dextran sulfate sodium(DSS)-induced enteritis.Methods A total of 1,260 healthy juvenile yellow catfish(Pelteobagrus fulvidraco),with an average body weight of 5.90±0.05 g,were randomly allocated into 7 experimental groups,each with 3 replicates.The fish were fed one of seven diets for 10 weeks:a normal-protein diet(42%;NP)and 6 low-protein diets(39%;LP)supplemented with graded levels of ECP at 0%(ECP0),1%(ECP1),2%(ECP2),3%(ECP3),4%(ECP4),and 5%(ECP5),respectively.Subsequently,48 fish from each group were selected to receive 1 mL of 6%DSS solution.Results Our findings demonstrated that:(1)The DSS+ECP0 group aggravated DSS-induced enteritis in juvenile yellow catfish compared to the DSS+NP group.(2)Dietary supplementation of ECP in LP diets significantly enhanced the enzymatic activity and levels of immunoreactive substances,including LZM,C3,C4,and ACP(P<0.05).Mechanistically,first,ECP supplementation modulated macrophage polarization by inhibiting the M1 phenotype while promoting the M2 phenotype,potentially through the JAK-STAT signaling pathway;second,dietary ECP suppressed the phosphorylation cascade of key necroptosis-related proteins,including RIP1,RIP3,and MLKL,potentially via the NF-κB and MAPK signaling pathways.(3)The DSS+ECP2 group demonstrated comparable or superior efficacy to the DSS+NP group in mitigating DSS-induced intestinal enteritis.Conclusions Our results demonstrated that ECP can alleviate DSS-induced enteritis by regulating macrophage polarization and reducing necroptosis.Furthermore,ECP supplementation effectively counteracted the exacerbation of enteritis caused by dietary protein reduction.These findings highlighted the effectiveness and feasibility of ECP in alleviating enteritis and saving protein.展开更多
Background Hypoxia is a pervasive challenge in aquaculture that poses a significant threat to aquatic organisms.Since fish cannot synthesize vitamin A endogenously,it must be supplied through diet,and it plays a vital...Background Hypoxia is a pervasive challenge in aquaculture that poses a significant threat to aquatic organisms.Since fish cannot synthesize vitamin A endogenously,it must be supplied through diet,and it plays a vital role in supporting fish stress resistance.This study aimed to investigate the protective effects of VA on the gills of adult grass carp(Ctenopharyngodon idella)against hypoxia and to elucidate the underlying mechanisms.Methods Six experimental diets with graded VA levels(375,862,1,614,2,099,2,786,and 3,118 IU/kg)were fed to grass carp(initial weight:726±1.2 g)for 60 d.After the trial,24 fish per treatment were selected,divided equally into normoxic and hypoxic groups,fasted for 24 h,and then subjected to a 96-h acute hypoxic challenge.Results The results demonstrated that VA supplementation mitigated hypoxia-induced damage in gill tissue,as evidenced by histological examination.Furthermore,VA alleviated oxidative stress,as indicated by reduced levels of lactate(LD),lactate dehydrogenase(LDH),reactive oxygen species(ROS),protein carbonyl(PC),and malondialdehyde(MDA).Further investigations indicated that VA alleviated mitochondrial stress,potentially through suppressing the canonical UPR^(mt) axis while activating both the UPR^(mt) sirtuin axis and the UPRIMS/Erα axis.VA also modulated mitochondrial mass via multiple mechanisms,including the promotion of mitochondrial biogenesis,maintenance of dynamics by stimulating fusion and reducing fission,and inhibition of mitophagy.The suppression of mitophagy likely involved downregulating both the Pink1/Parkin-dependent pathway and the Hif1a-Bnip3 pathway.Taken together,these adaptations suggested an essential role for VA in preserving mitochondrial homeostasis.Based on the quadratic regression analysis of ROS and MDA levels from the hypoxic group,the estimated VA requirements for adult grass carp were 2,013 and 2,056 IU/kg diet,respectively.Conclusions In summary,this study provided the first evidence that VA conferred protective effects against hypoxiainduced gill damage in grass carp.展开更多
Background As living standards improve,consumers are placing greater emphasis on the enhancement of fish flesh quality,making its improvement increasingly critical.Plant-derived polysaccharides positively affect the i...Background As living standards improve,consumers are placing greater emphasis on the enhancement of fish flesh quality,making its improvement increasingly critical.Plant-derived polysaccharides positively affect the improvement of animal flesh quality.Panax ginseng leaf polysaccharides(PGLP)have a similar composition and lower cost compared with Panax ginseng root polysaccharides.However,its function and application effects in grass carp(Ctenopharyngodon idella)are unclear.Methods A total of 540 sub-adult grass carp(679±1.29 g),one of the important economic fish species,were used as experimental models and fed diets supplemented with 0,100,200,300,400,or 500 mg/kg PGLP for 60 d.After 60 d,grass carp were weighed,and their muscles were collected to explore the effects of PGLP on the growth and development of myofibers and energy metabolism-related parameters.Results Our study found that PGLP increased the growth performance and muscle nutritional composition as well as improved muscle hardness,springiness,cohesiveness,chewiness,and hyperplasia of myofibers of sub-adult grass carp.Besides,PGLP promoted muscle energy metabolism by increasing creatine,glycogen,pyruvate,and acetyl-CoA contents and creatine kinase(CK),pyruvate kinase(PK),phosphofructokinase(PFK),and hexokinase(HK)activities,while decreasing lactate dehydrogenase(LDH)activity and lactate content in fish muscle.Finally,our study found that PGLP enhanced mitochondrial function by increasing the protein expression of mitochondrial complexes I–V,biogenesis,and fusion and decreasing autophagy and fission in fish muscle.Conclusions PGLP improved growth performance and flesh quality of sub-adult grass carp,which may be related to enhancing hyperplasia of myofibers by promoting energy metabolism.We concluded that the recommended amount of PGLP in sub-adult grass carp feed to optimize growth performance is 100–200 mg/kg.This study provides a theoretical basis for the application of PGLP in fish feed and for the analysis of the mechanism of nutrition and feed regulating fish flesh quality,which is of great significance.展开更多
Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on ...Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on gut health remain unclear.In this experiment,we investigated the influence of C.somerae(CGMCC No.28843)on the growth performance,intestinal digestive and absorptive capacity,and intestinal structural integrity of juvenile grass carp(Ctenopharyngodon idella)and explored its potential mechanisms.Methods A cohort of 2,160 juvenile grass carp with an initial mean body weight of 11.30±0.01 g were randomly allocated into 6 treatment groups,each comprising 6 replicates(60 fish per replicate).The experimental diets were supplemented with C.somerae at graded levels of 0.00(control),0.68×10^(9),1.35×10^(9),2.04×10^(9),2.70×10^(9),and 3.40×10^(9)cells/kg feed.Following a 10-week experimental period,biological samples were collected for subsequent analyses.Results Dietary supplementation with C.somerae at 1.35×10^(9)cells/kg significantly enhanced growth performance,intestinal development,and nutrient retention rate in juvenile grass carp(P<0.05).The treatment resulted in increased intestinal acetic acid concentration and enhanced activities of digestive enzymes and brush border enzymes(P<0.05).Furthermore,it reduced intestinal permeability(P<0.05),preserved tight junctions(TJ)ultrastructural integrity,and increased the expression of TJ and adherens junctions(AJ)biomarkers at both protein and transcriptional levels(P<0.05).Mechanistically,these effects may be correlated with enhanced antioxidant capacity and coordinated modulation of the RhoA/ROCK,Sirt1,and PI3K/AKT signaling pathways.The appropriate supplementation levels,based on weight gain rate,feed conversion ratio,the activity of serum diamine oxidase and the content of lipopolysaccharide,were 1.27×10^(9),1.27×10^(9),1.34×10^(9)and 1.34×10^(9)cells/kg,respectively.Conclusions C.somerae improved intestinal digestive and absorptive capacity of juvenile grass carp,maintained intestinal structural integrity,and thus promoted their growth and development.This work demonstrates the potential of C.somerae as a probiotic for aquatic animals and provides a theoretical basis for its utilization in aquaculture.展开更多
Enzymatic cottonseed protein(ECP)is a functional peptide product reported to have antioxidant and immunomodulatory properties.This study focused on how the intestinal apical junction complex(AJC)structure,microbial co...Enzymatic cottonseed protein(ECP)is a functional peptide product reported to have antioxidant and immunomodulatory properties.This study focused on how the intestinal apical junction complex(AJC)structure,microbial composition,growth performance,and digestive and absorptive capacity were affected by adding ECP to diets with a 3% crude protein(CP)reduction.A total of 1260 healthy juvenile yellow catfish weighing 5.90±0.05 g were randomly assigned to seven experimental groups,each consisting of three replicates.A normal protein(NP)diet(42%CP)or one of six low protein(LP)diets(39%CP)with differing amounts of ECP(0%,1%,2%,3%,4%,and 5%,respectively)given for ten weeks.Dietary CP levels that were lowered by 3%(from 42%to 39%)disrupted the intestinal AJC structure and reduced growth performance,including specific growth rate(SGR;P=0.042)and feed intake(FI;P=0.001)and digestive and absorptive capacity,including the activities of alkaline phosphatase(AKP;P<0.001),γ-glutamyl transpeptidase(γ-GT;P<0.001),Na^(+)/K^(+)-ATPase(P<0.001),pepsin(P<0.001),lipase(P=0.009),amylase(P<0.001),chymotrypsin(P<0.001),and carboxypeptidase(CPs;P=0.005).Adding 2%ECP to the LP diets(39%CP)improved SGR(P=0.001),FI(P<0.001),pepsin activity(P<0.001),the activities of γ-GT(P<0.001),AKP(P<0.001),lipase(P<0.001),amylase(P<0.001),Na^(+)/K^(+)-ATPase(P<0.001),chymotrypsin(P<0.001),aminopeptidases(Aps;P<0.001),and CPs(P<0.001).The factors that control the expression of peptide transporter 1(PepT1),such as nuclear factor erythroid 2-related factor 2(nrf2),Janus kinase 2(jak2),caudal type homeobox transcription factor 2(CDX2),and specificity protein 1(SP1),as well as those that affect its function,such as protein sodium/hydrogen exchange isoform 3(NHE3)and PDZ domain containing 1(PDZK1),may be responsible for the increase in the expression of PepT1(P=0.008).Furthermore,the Ras homolog family member A(RhoA)/Rho-associated kinase(ROCK)signaling pathway may be involved in improving intestinal AJC structure.ECP also increased the relative abundance of beneficial bacteria,including Fusobacteria,Firmicutes,Cetobacterium,and Acinetobacter,while decreasing that of pathogenic bacteria,such as Spirochaetes,Actinomycetes,Brevinema,and Plesiomonas.A 3% decrease in dietary CP levels and supplementation with 2%ECP restored growth performance,intestinal structural indices,and digestive and absorptive capacity to levels equivalent to or better than those of the NP.Furthermore,chymotrypsin and percentage weight gain broken-line regression analysis revealed that the optimal ECP additions for juvenile catfish were 2.08% and 2.2%,respectively.展开更多
Arecoline is an alkaloid extracted from the plant betel nut with important pharmacological effects and is an agonist at muscarinic receptors(M receptors).In this study,we investigated the effects of dietary arecoline ...Arecoline is an alkaloid extracted from the plant betel nut with important pharmacological effects and is an agonist at muscarinic receptors(M receptors).In this study,we investigated the effects of dietary arecoline supplementation on hepatopancreatic and muscle glycolipid metabolism in adult grass carp(Ctenopharyngodon idellus).A total of 450 healthy adult grass carp with an initial body weight of 607.87±1.82 g were randomly divided into six experimental groups and fed six levels(0,0.5,1.0,1.5,2.0,and 2.5 mg/kg diet)of arecoline for 60 days.The results showed that feed supplemented with 1.0 mg/kg arecoline up-regulated mRNA levels of M3,and promoted glucose(GLU)and fatty acid metabolism(P<0.05)both in hepatopancreas and muscle.The promotion of glycolipid metabolism by arecoline can be achieved through three pathways.Firstly,arecoline alleviated endoplasmic reticulum(ER)stress in grass carp muscle by suppressing the mRNA levels of ER stress-related genes atf4,chop,ire1,and xbp1 as well as the protein expression of p-PERK and p-IRE1(P<0.05).Secondly,arecoline protected mitochondrial function by promoting the mitochondrial respiratory chain complex IeV-related protein expression and triggering the mitochondrial unfolded protein response(UPRmt)(P<0.05).Finally,arecoline promoted close communication between the ER and mitochondria by increasing the expression of the mitochondria-associated endoplasmic reticulum membrane(MAM)tight junction proteins GRP75 and PACS2 as well as the calcium transporter proteins SERCA1 and IP3R,which in turn promoted lipid metabolism by increasing the protein expression of DGAT2(P<0.05).In conclusion,we found for the first time that dietary arecoline promoted GLU and fatty acid metabolism in hepatopancreas and muscle,which may be related to the regulatory effects of MAM on ER and mitochondria.展开更多
Choline is an essential nutrient for fish,and its metabolites are components of all membrane systems.Membrane phospholipids play an important role in maintaining the morphology and function of mitochondria,which could...Choline is an essential nutrient for fish,and its metabolites are components of all membrane systems.Membrane phospholipids play an important role in maintaining the morphology and function of mitochondria,which could affect the growth and development of myofiber.To evaluate the effects of choline on growth performance,muscle fiber development,and mitochondrial morphology and function in grass carp,six diets containing graded choline levels[154.0(basal diet),321.8,672.2,1024.9,1373.2,and 1722.8 mg/kg]were fed to 450 sub-adult grass carp(583.44±1.65 g)for 56 d.The fish were divided into six groups with three replicates of 25 fish each.The results showed as follows:1)compared with the control group,choline increased the growth performance,muscle protein content and choline deposition in sub-adult grass carp(P<0.05),while decreased adhesive force(P<0.001)and cooking loss(P=0.037),thus improving fish flesh quality.2)Dietary choline levels of 1024.9 to 1373.2 mg/kg significantly increased the frequency of myofibers with diameter>100μm(P=0.002)and fusion coefficient(P<0.001).The mRNA expression of MyoG(P<0.001),MyoD(P<0.001),Myf5(P=0.005),MRF4(P=0.028),MYHC(P=0.005),and myomaker(P<0.001)increased quadratically with dietary choline,whereas MSTN expression was non-significantly lower than controls at 1024.9 to 1373.2 mg/kg(P=0.078).Furthermore,choline increased the mRNA expression of IGF1,PI3K,AKT,and TOR(P<0.05)and decreased the mRNA expression of FoxO3a and MuRF1(P<0.05).3)Muscle adenosine triphosphate(ATP)content(P<0.001),protein levels of NDUFV1(P=0.004)and ATP5A1(P=0.046),and the mRNA levels of NRF1(P=0.017),TFAM(P=0.014),and OPA1(P<0.001)were increased quadratically.Conversely,the mRNA levels of DRP1(P<0.001),PINK(P<0.001),and PARKIN(P=0.002)were decreased quadratically.4)According to the quadratic regression analysis of percent weight gain(PWG)and muscle ATP content,the choline requirement of sub-adult grass carp was 951.2 and 1084.9 mg/kg diet,respectively.In summary,optimal levels of dietary choline improved the myofiber hypertrophy in grass carp,which was associated with upregulation of myogenesis regulator and the activation of the IGF1/PI3K/AKT signaling pathway,and maintained mitochondrial stability probably via regulating mitochondrial quality control.展开更多
The beneficial effects of folic acid(FA)on intestinal barrier function are well recognized,however the underlying molecular mechanisms remain largely unexplored.This study aimed to investigate the effects of dietary F...The beneficial effects of folic acid(FA)on intestinal barrier function are well recognized,however the underlying molecular mechanisms remain largely unexplored.This study aimed to investigate the effects of dietary FA on intestinal epithelial function in grass carp,and to reveal the potential molecular mechanism.The total of 450 healthy grass carp(686.83±1.31 g)were randomly divided into 6 groups(18 barrels,25 fish per barrel),and fed diets containing levels of FA(0.57,1.11,1.53,2.08,2.64,and 3.15 mg/kg diet)for 8 weeks.The results showed that,compared with the control group,a dietary FA level of 1.11 mg/kg significantly significantly increased FBW,PWG,WG,SGR and FI,as well as FA and methionine cycling in grass carp(P<0.05).Dietary FA also promoted the intestinal barrier function and proliferation of intestinal epithelial cells(P<0.05).Further,dietary FA increased the protein levels of the DNA methyltransferase(DNMT)family and the protein phosphatase 2A(PP2A)-p38 signaling pathway was significantly activated in fish fed the 1.11 mg/kg FA diet(P<0.05).In conclusion,dietary FA improved intestinal epithelial function in grass carp by modulating the expression of DNMTs and activating the PP2A-p38 signaling pathway.Based on percent weight gain,the optimal requirement of FA for sub-adult grass carp(686.8-1264.7 g)was estimated to be 1.03 mg/kg.展开更多
The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding.However,traditional methods are damaging to the animals,causing the waste of a quality parent.Ultrasound...The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding.However,traditional methods are damaging to the animals,causing the waste of a quality parent.Ultrasound imaging as a noninvasive technique is a candidate substitute.This study aimed to verify the application of ultrasonography to the assessment of abalone gonad condition.Pacific abalones(n=20)were randomly selected for ultrasonography,another six abalones in different gonad maturation stages(mature,between mature and immature,and immature)were also subjected to the same detection and histological analysis.Abalones(n=10)were induced to spawn,and the changes in the gonad index and the types of germ cells were determined before and after spawning.Thirty-six female abalones were selected and divided into a high-gonad index group(HGI)and a low-gonad index group(LGI)according to the gonad index determined by ultrasonography,and their reproductive performance was compared during the entire breeding process.There was no significant difference in gonad index or gonad relative average thickness(GRAT)obtained from ultrasonography and histological methods.The gonad index and GRAT measured by ultrasound images significantly decreased after spawning.After spawning,a minimal quantity of mature gametes remained in gonad tissue as reflected in histology images.In a reproductive trial,the HGI group showed comprehensive and overwhelming reproductive advantages compared to the LGI group in total fecundity,relative fecundity,fertilization rate,hatching rate,abnormality rate,and attachment rate.Ultrasonography was demonstrated to be useful as a noninvasive method to evaluate abalone gonad condition.The ultimate goal is to achieve tracing and monitoring the abalone reproductive cycle through the ultrasound technique.展开更多
基金financially supported by the Sichuan Science and Technology Program(2024YFNH0016,2024NSFSC2072)the earmarked fund for CARS(CARS-45)+2 种基金the National Science Fund for Distinguished Young Scholars of China(32425056)the National Key Research and Development Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-15)。
文摘Background Environmental hypoxia is a common phenomenon in aquaculture,which causes gill tissue injury in fish.Glutathione(GSH)is a vital antioxidant in animal tissues,and its levels decrease under hypoxic conditions.However,the effects of glutathione on fish under hypoxic stress remain poorly understood.This study aimed to investigate the impact of glutathione on gill tissue damage in fish under hypoxic stress and explore the underlying mechanisms.Methods Six experimental diets with varying glutathione concentrations.The actual glutathione levels in these diets,measured by high-performance liquid chromatography,were 0.00,145.95,291.90,437.85,583.80,and 729.75 mg/kg,respectively.Fish were fed these diets for 70 d,after which a 96-h hypoxic stress experiment was conducted.The experiment was set up with normoxic and hypoxic groups,in which the dissolved oxygen in the group was 6 mg/L,and that in the group was 1 mg/L.Results This research revealed that glutathione could enhance the growth performance and antioxidant capability of juvenile grass carp while mitigating the structural damage to gill tissues induced by hypoxia stress.Mechanistic investigations further indicated that glutathione mitigated hypoxia-induced oxidative injury in gill tissues and improved their antioxidant capacity.In addition,glutathione attenuated gill apoptosis induced by hypoxia stress.Glutathione also inhibited the initiation,nucleation,elongation,and degradation phases of autophagy,thereby attenuating hypoxia-induced gill autophagy.Moreover,glutathione was found to alleviate hypoxia-induced endoplasmic reticulum stress(ERS)in gills,a response potentially linked to the suppression of PERK,IRE1,and ATF6 signaling pathways.Finally,based on the ROS and PC contents in gill tissue,the optimum glutathione supplementation levels for juvenile grass carp under hypoxia stress were 437.10 and 495.00 mg/kg,respectively.Conclusions In conclusion,our experimental results demonstrated the effectiveness of glutathione in alleviating gill tissue damage caused by hypoxic stress.This study confirms the feasibility and effectiveness of dietary glutathione addition to alleviate hypoxic stress in fish.
基金National Science Fund for Distinguished Young Scholars of China(32425056)National Natural Science Foundation of China(U23A20250)+2 种基金the earmarked fund for CARS(CARS-45)the National Key R&D Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-15).
文摘Background In intensive aquaculture systems,the frequent incidence of enteritis reduces production efficiency and results in significant economic losses.Protein feeds account for 40%–60%of aquafeed expenses,and with the growth of intensive aquaculture,demand for fishmeal as a key protein source outstrips supply,driving up prices.This study investigated the therapeutic potential of reducing dietary protein levels by 3%and adding enzymatic cottonseed protein(ECP)in juvenile yellow catfish with dextran sulfate sodium(DSS)-induced enteritis.Methods A total of 1,260 healthy juvenile yellow catfish(Pelteobagrus fulvidraco),with an average body weight of 5.90±0.05 g,were randomly allocated into 7 experimental groups,each with 3 replicates.The fish were fed one of seven diets for 10 weeks:a normal-protein diet(42%;NP)and 6 low-protein diets(39%;LP)supplemented with graded levels of ECP at 0%(ECP0),1%(ECP1),2%(ECP2),3%(ECP3),4%(ECP4),and 5%(ECP5),respectively.Subsequently,48 fish from each group were selected to receive 1 mL of 6%DSS solution.Results Our findings demonstrated that:(1)The DSS+ECP0 group aggravated DSS-induced enteritis in juvenile yellow catfish compared to the DSS+NP group.(2)Dietary supplementation of ECP in LP diets significantly enhanced the enzymatic activity and levels of immunoreactive substances,including LZM,C3,C4,and ACP(P<0.05).Mechanistically,first,ECP supplementation modulated macrophage polarization by inhibiting the M1 phenotype while promoting the M2 phenotype,potentially through the JAK-STAT signaling pathway;second,dietary ECP suppressed the phosphorylation cascade of key necroptosis-related proteins,including RIP1,RIP3,and MLKL,potentially via the NF-κB and MAPK signaling pathways.(3)The DSS+ECP2 group demonstrated comparable or superior efficacy to the DSS+NP group in mitigating DSS-induced intestinal enteritis.Conclusions Our results demonstrated that ECP can alleviate DSS-induced enteritis by regulating macrophage polarization and reducing necroptosis.Furthermore,ECP supplementation effectively counteracted the exacerbation of enteritis caused by dietary protein reduction.These findings highlighted the effectiveness and feasibility of ECP in alleviating enteritis and saving protein.
基金funded by the Sichuan Science and Technology Program(2024YFNH0016)the earmarked fund for CARS(CARS-45)+1 种基金the National Science Fund for Distinguished Young Scholars of China(32425056)the National Key R&D Program of China(2023YFD2400600)。
文摘Background Hypoxia is a pervasive challenge in aquaculture that poses a significant threat to aquatic organisms.Since fish cannot synthesize vitamin A endogenously,it must be supplied through diet,and it plays a vital role in supporting fish stress resistance.This study aimed to investigate the protective effects of VA on the gills of adult grass carp(Ctenopharyngodon idella)against hypoxia and to elucidate the underlying mechanisms.Methods Six experimental diets with graded VA levels(375,862,1,614,2,099,2,786,and 3,118 IU/kg)were fed to grass carp(initial weight:726±1.2 g)for 60 d.After the trial,24 fish per treatment were selected,divided equally into normoxic and hypoxic groups,fasted for 24 h,and then subjected to a 96-h acute hypoxic challenge.Results The results demonstrated that VA supplementation mitigated hypoxia-induced damage in gill tissue,as evidenced by histological examination.Furthermore,VA alleviated oxidative stress,as indicated by reduced levels of lactate(LD),lactate dehydrogenase(LDH),reactive oxygen species(ROS),protein carbonyl(PC),and malondialdehyde(MDA).Further investigations indicated that VA alleviated mitochondrial stress,potentially through suppressing the canonical UPR^(mt) axis while activating both the UPR^(mt) sirtuin axis and the UPRIMS/Erα axis.VA also modulated mitochondrial mass via multiple mechanisms,including the promotion of mitochondrial biogenesis,maintenance of dynamics by stimulating fusion and reducing fission,and inhibition of mitophagy.The suppression of mitophagy likely involved downregulating both the Pink1/Parkin-dependent pathway and the Hif1a-Bnip3 pathway.Taken together,these adaptations suggested an essential role for VA in preserving mitochondrial homeostasis.Based on the quadratic regression analysis of ROS and MDA levels from the hypoxic group,the estimated VA requirements for adult grass carp were 2,013 and 2,056 IU/kg diet,respectively.Conclusions In summary,this study provided the first evidence that VA conferred protective effects against hypoxiainduced gill damage in grass carp.
基金supported by National Natural Science Foundation of China(U23A20250)the earmarked fund for CARS(CARS-45)+2 种基金the National Key R&D Program of China(2023YFD2400600)Sichuan Provincial Science and Technology Innovation Talent Project(2023JDRC0043)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-15)。
文摘Background As living standards improve,consumers are placing greater emphasis on the enhancement of fish flesh quality,making its improvement increasingly critical.Plant-derived polysaccharides positively affect the improvement of animal flesh quality.Panax ginseng leaf polysaccharides(PGLP)have a similar composition and lower cost compared with Panax ginseng root polysaccharides.However,its function and application effects in grass carp(Ctenopharyngodon idella)are unclear.Methods A total of 540 sub-adult grass carp(679±1.29 g),one of the important economic fish species,were used as experimental models and fed diets supplemented with 0,100,200,300,400,or 500 mg/kg PGLP for 60 d.After 60 d,grass carp were weighed,and their muscles were collected to explore the effects of PGLP on the growth and development of myofibers and energy metabolism-related parameters.Results Our study found that PGLP increased the growth performance and muscle nutritional composition as well as improved muscle hardness,springiness,cohesiveness,chewiness,and hyperplasia of myofibers of sub-adult grass carp.Besides,PGLP promoted muscle energy metabolism by increasing creatine,glycogen,pyruvate,and acetyl-CoA contents and creatine kinase(CK),pyruvate kinase(PK),phosphofructokinase(PFK),and hexokinase(HK)activities,while decreasing lactate dehydrogenase(LDH)activity and lactate content in fish muscle.Finally,our study found that PGLP enhanced mitochondrial function by increasing the protein expression of mitochondrial complexes I–V,biogenesis,and fusion and decreasing autophagy and fission in fish muscle.Conclusions PGLP improved growth performance and flesh quality of sub-adult grass carp,which may be related to enhancing hyperplasia of myofibers by promoting energy metabolism.We concluded that the recommended amount of PGLP in sub-adult grass carp feed to optimize growth performance is 100–200 mg/kg.This study provides a theoretical basis for the application of PGLP in fish feed and for the analysis of the mechanism of nutrition and feed regulating fish flesh quality,which is of great significance.
基金financially supported by the earmarked fund for the earmarked fund for CARS(CARS-45)National Science Fund for Distinguished Young Scholars of China(32425056)+1 种基金the National Key R&D Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-16).
文摘Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on gut health remain unclear.In this experiment,we investigated the influence of C.somerae(CGMCC No.28843)on the growth performance,intestinal digestive and absorptive capacity,and intestinal structural integrity of juvenile grass carp(Ctenopharyngodon idella)and explored its potential mechanisms.Methods A cohort of 2,160 juvenile grass carp with an initial mean body weight of 11.30±0.01 g were randomly allocated into 6 treatment groups,each comprising 6 replicates(60 fish per replicate).The experimental diets were supplemented with C.somerae at graded levels of 0.00(control),0.68×10^(9),1.35×10^(9),2.04×10^(9),2.70×10^(9),and 3.40×10^(9)cells/kg feed.Following a 10-week experimental period,biological samples were collected for subsequent analyses.Results Dietary supplementation with C.somerae at 1.35×10^(9)cells/kg significantly enhanced growth performance,intestinal development,and nutrient retention rate in juvenile grass carp(P<0.05).The treatment resulted in increased intestinal acetic acid concentration and enhanced activities of digestive enzymes and brush border enzymes(P<0.05).Furthermore,it reduced intestinal permeability(P<0.05),preserved tight junctions(TJ)ultrastructural integrity,and increased the expression of TJ and adherens junctions(AJ)biomarkers at both protein and transcriptional levels(P<0.05).Mechanistically,these effects may be correlated with enhanced antioxidant capacity and coordinated modulation of the RhoA/ROCK,Sirt1,and PI3K/AKT signaling pathways.The appropriate supplementation levels,based on weight gain rate,feed conversion ratio,the activity of serum diamine oxidase and the content of lipopolysaccharide,were 1.27×10^(9),1.27×10^(9),1.34×10^(9)and 1.34×10^(9)cells/kg,respectively.Conclusions C.somerae improved intestinal digestive and absorptive capacity of juvenile grass carp,maintained intestinal structural integrity,and thus promoted their growth and development.This work demonstrates the potential of C.somerae as a probiotic for aquatic animals and provides a theoretical basis for its utilization in aquaculture.
基金National Science Fund for Distinguished Young Scholars of China(32425056)the earmarked fund for CARS(CARS-45)+1 种基金the National Key R&D Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-15).
文摘Enzymatic cottonseed protein(ECP)is a functional peptide product reported to have antioxidant and immunomodulatory properties.This study focused on how the intestinal apical junction complex(AJC)structure,microbial composition,growth performance,and digestive and absorptive capacity were affected by adding ECP to diets with a 3% crude protein(CP)reduction.A total of 1260 healthy juvenile yellow catfish weighing 5.90±0.05 g were randomly assigned to seven experimental groups,each consisting of three replicates.A normal protein(NP)diet(42%CP)or one of six low protein(LP)diets(39%CP)with differing amounts of ECP(0%,1%,2%,3%,4%,and 5%,respectively)given for ten weeks.Dietary CP levels that were lowered by 3%(from 42%to 39%)disrupted the intestinal AJC structure and reduced growth performance,including specific growth rate(SGR;P=0.042)and feed intake(FI;P=0.001)and digestive and absorptive capacity,including the activities of alkaline phosphatase(AKP;P<0.001),γ-glutamyl transpeptidase(γ-GT;P<0.001),Na^(+)/K^(+)-ATPase(P<0.001),pepsin(P<0.001),lipase(P=0.009),amylase(P<0.001),chymotrypsin(P<0.001),and carboxypeptidase(CPs;P=0.005).Adding 2%ECP to the LP diets(39%CP)improved SGR(P=0.001),FI(P<0.001),pepsin activity(P<0.001),the activities of γ-GT(P<0.001),AKP(P<0.001),lipase(P<0.001),amylase(P<0.001),Na^(+)/K^(+)-ATPase(P<0.001),chymotrypsin(P<0.001),aminopeptidases(Aps;P<0.001),and CPs(P<0.001).The factors that control the expression of peptide transporter 1(PepT1),such as nuclear factor erythroid 2-related factor 2(nrf2),Janus kinase 2(jak2),caudal type homeobox transcription factor 2(CDX2),and specificity protein 1(SP1),as well as those that affect its function,such as protein sodium/hydrogen exchange isoform 3(NHE3)and PDZ domain containing 1(PDZK1),may be responsible for the increase in the expression of PepT1(P=0.008).Furthermore,the Ras homolog family member A(RhoA)/Rho-associated kinase(ROCK)signaling pathway may be involved in improving intestinal AJC structure.ECP also increased the relative abundance of beneficial bacteria,including Fusobacteria,Firmicutes,Cetobacterium,and Acinetobacter,while decreasing that of pathogenic bacteria,such as Spirochaetes,Actinomycetes,Brevinema,and Plesiomonas.A 3% decrease in dietary CP levels and supplementation with 2%ECP restored growth performance,intestinal structural indices,and digestive and absorptive capacity to levels equivalent to or better than those of the NP.Furthermore,chymotrypsin and percentage weight gain broken-line regression analysis revealed that the optimal ECP additions for juvenile catfish were 2.08% and 2.2%,respectively.
基金supported by the National Science Fund for Distinguished Young Scholars of China(32425056)the National Key R&D Program of China(2023YFD2400600)+1 种基金National Natural Science Foundation of China(U23A20250)the earmarked fund for CARS(CARS-45).
文摘Arecoline is an alkaloid extracted from the plant betel nut with important pharmacological effects and is an agonist at muscarinic receptors(M receptors).In this study,we investigated the effects of dietary arecoline supplementation on hepatopancreatic and muscle glycolipid metabolism in adult grass carp(Ctenopharyngodon idellus).A total of 450 healthy adult grass carp with an initial body weight of 607.87±1.82 g were randomly divided into six experimental groups and fed six levels(0,0.5,1.0,1.5,2.0,and 2.5 mg/kg diet)of arecoline for 60 days.The results showed that feed supplemented with 1.0 mg/kg arecoline up-regulated mRNA levels of M3,and promoted glucose(GLU)and fatty acid metabolism(P<0.05)both in hepatopancreas and muscle.The promotion of glycolipid metabolism by arecoline can be achieved through three pathways.Firstly,arecoline alleviated endoplasmic reticulum(ER)stress in grass carp muscle by suppressing the mRNA levels of ER stress-related genes atf4,chop,ire1,and xbp1 as well as the protein expression of p-PERK and p-IRE1(P<0.05).Secondly,arecoline protected mitochondrial function by promoting the mitochondrial respiratory chain complex IeV-related protein expression and triggering the mitochondrial unfolded protein response(UPRmt)(P<0.05).Finally,arecoline promoted close communication between the ER and mitochondria by increasing the expression of the mitochondria-associated endoplasmic reticulum membrane(MAM)tight junction proteins GRP75 and PACS2 as well as the calcium transporter proteins SERCA1 and IP3R,which in turn promoted lipid metabolism by increasing the protein expression of DGAT2(P<0.05).In conclusion,we found for the first time that dietary arecoline promoted GLU and fatty acid metabolism in hepatopancreas and muscle,which may be related to the regulatory effects of MAM on ER and mitochondria.
基金financial supported by the National Key R&D Program of China(2023YFD2400600)Sichuan Provincial Science and Technology Innovation Talent Project(2023JDRC0043)+1 种基金the earmarked fund for CARS(CARS-45)National Science Fund for Distinguished Young Scholars of China(32425056).
文摘Choline is an essential nutrient for fish,and its metabolites are components of all membrane systems.Membrane phospholipids play an important role in maintaining the morphology and function of mitochondria,which could affect the growth and development of myofiber.To evaluate the effects of choline on growth performance,muscle fiber development,and mitochondrial morphology and function in grass carp,six diets containing graded choline levels[154.0(basal diet),321.8,672.2,1024.9,1373.2,and 1722.8 mg/kg]were fed to 450 sub-adult grass carp(583.44±1.65 g)for 56 d.The fish were divided into six groups with three replicates of 25 fish each.The results showed as follows:1)compared with the control group,choline increased the growth performance,muscle protein content and choline deposition in sub-adult grass carp(P<0.05),while decreased adhesive force(P<0.001)and cooking loss(P=0.037),thus improving fish flesh quality.2)Dietary choline levels of 1024.9 to 1373.2 mg/kg significantly increased the frequency of myofibers with diameter>100μm(P=0.002)and fusion coefficient(P<0.001).The mRNA expression of MyoG(P<0.001),MyoD(P<0.001),Myf5(P=0.005),MRF4(P=0.028),MYHC(P=0.005),and myomaker(P<0.001)increased quadratically with dietary choline,whereas MSTN expression was non-significantly lower than controls at 1024.9 to 1373.2 mg/kg(P=0.078).Furthermore,choline increased the mRNA expression of IGF1,PI3K,AKT,and TOR(P<0.05)and decreased the mRNA expression of FoxO3a and MuRF1(P<0.05).3)Muscle adenosine triphosphate(ATP)content(P<0.001),protein levels of NDUFV1(P=0.004)and ATP5A1(P=0.046),and the mRNA levels of NRF1(P=0.017),TFAM(P=0.014),and OPA1(P<0.001)were increased quadratically.Conversely,the mRNA levels of DRP1(P<0.001),PINK(P<0.001),and PARKIN(P=0.002)were decreased quadratically.4)According to the quadratic regression analysis of percent weight gain(PWG)and muscle ATP content,the choline requirement of sub-adult grass carp was 951.2 and 1084.9 mg/kg diet,respectively.In summary,optimal levels of dietary choline improved the myofiber hypertrophy in grass carp,which was associated with upregulation of myogenesis regulator and the activation of the IGF1/PI3K/AKT signaling pathway,and maintained mitochondrial stability probably via regulating mitochondrial quality control.
基金The earmarked fund for CARS(CARS-45),National Science Fund for Distinguished Young Scholars of China(32425056)the National Key R&D Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-15).
文摘The beneficial effects of folic acid(FA)on intestinal barrier function are well recognized,however the underlying molecular mechanisms remain largely unexplored.This study aimed to investigate the effects of dietary FA on intestinal epithelial function in grass carp,and to reveal the potential molecular mechanism.The total of 450 healthy grass carp(686.83±1.31 g)were randomly divided into 6 groups(18 barrels,25 fish per barrel),and fed diets containing levels of FA(0.57,1.11,1.53,2.08,2.64,and 3.15 mg/kg diet)for 8 weeks.The results showed that,compared with the control group,a dietary FA level of 1.11 mg/kg significantly significantly increased FBW,PWG,WG,SGR and FI,as well as FA and methionine cycling in grass carp(P<0.05).Dietary FA also promoted the intestinal barrier function and proliferation of intestinal epithelial cells(P<0.05).Further,dietary FA increased the protein levels of the DNA methyltransferase(DNMT)family and the protein phosphatase 2A(PP2A)-p38 signaling pathway was significantly activated in fish fed the 1.11 mg/kg FA diet(P<0.05).In conclusion,dietary FA improved intestinal epithelial function in grass carp by modulating the expression of DNMTs and activating the PP2A-p38 signaling pathway.Based on percent weight gain,the optimal requirement of FA for sub-adult grass carp(686.8-1264.7 g)was estimated to be 1.03 mg/kg.
基金supported by grants from National Natural Science Foundation of China(No.U22A20530)the Key S&T Program of Fujian Province(No.2020NZ08003)+1 种基金Seed Industry Innovation and Industrialization in Fujian Province(No.2021FJSCZY02)the Earmarked Fund for CARS(No.CARS-49).
文摘The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding.However,traditional methods are damaging to the animals,causing the waste of a quality parent.Ultrasound imaging as a noninvasive technique is a candidate substitute.This study aimed to verify the application of ultrasonography to the assessment of abalone gonad condition.Pacific abalones(n=20)were randomly selected for ultrasonography,another six abalones in different gonad maturation stages(mature,between mature and immature,and immature)were also subjected to the same detection and histological analysis.Abalones(n=10)were induced to spawn,and the changes in the gonad index and the types of germ cells were determined before and after spawning.Thirty-six female abalones were selected and divided into a high-gonad index group(HGI)and a low-gonad index group(LGI)according to the gonad index determined by ultrasonography,and their reproductive performance was compared during the entire breeding process.There was no significant difference in gonad index or gonad relative average thickness(GRAT)obtained from ultrasonography and histological methods.The gonad index and GRAT measured by ultrasound images significantly decreased after spawning.After spawning,a minimal quantity of mature gametes remained in gonad tissue as reflected in histology images.In a reproductive trial,the HGI group showed comprehensive and overwhelming reproductive advantages compared to the LGI group in total fecundity,relative fecundity,fertilization rate,hatching rate,abnormality rate,and attachment rate.Ultrasonography was demonstrated to be useful as a noninvasive method to evaluate abalone gonad condition.The ultimate goal is to achieve tracing and monitoring the abalone reproductive cycle through the ultrasound technique.
