Heat stress(HS)has been shown to adversely affect fish livers and can lead to extensive apoptosis.To investigate the relationship between endoplasmic reticulum(ER)stress and HS-induced apoptosis in fish livers,we isol...Heat stress(HS)has been shown to adversely affect fish livers and can lead to extensive apoptosis.To investigate the relationship between endoplasmic reticulum(ER)stress and HS-induced apoptosis in fish livers,we isolated and cultured primary hepatocytes of largemouth bass,Micropterus salmoides by trypsin method,then established an in-vitro model of liver cells under HS(35℃).The contents of lactic dehydrogenase(LDH)and hydrogen peroxide(H2O2)were determined to evaluate the effects of HS on hepatocyte injury and oxidative stress.RT-qPCR was performed to discover the key genes in unfolded protein response(UPR)pathways involved at different HS duration.ERS inhibitor 4-PBA and IRE1αinhibitor 4μ8C were used to further investigate the effects of HS on IRE1αapoptosis pathway in hepatocytes.Results show that HS led to significant increases in the release of LDH,the content of H2O2,and the expressions of oxidative protein folding genes(ero1αand pdi)under HS,suggesting severe hepatocyte injury and oxidative stress happened in heat-stressed largemouth bass hepatocytes.The continuous activation of IRE1αpathway genes(grp78,grp94,atf6,perk,eif2a,atf4,chop,ire1α,traf2,ask1,jnk1,and jnk2)indicated that HS led significantly to ER stress.In particular,the mRNA expression levels of ER stress-related genes(grp78,grp94,atf6,perk,ire1α,chop,jnk1,and jnk2)in the high temperature(HT)+4-PBA group and the HT+4μ8C group were significantly down-regulated under HS.After 4μ8C treatment,the expression levels of apoptosis-related genes(caspase-2,caspase-3,caspase-6,caspase-7,caspase-8,caspase-9,and caspase-10)and LDH content were significantly decreased,whereas the cell survival rate was significantly increased when given 4-PBA or 4μ8C treatment.These findings demonstrate that HS could induce liver apoptosis of largemouth bass through the IRE1αpathway,which may act as a key switch mediating liver apoptosis of largemouth bass under HS.展开更多
The intra-population phylogenetic relationship between Micropterus salmoides and Tilapia nilotica was analyzed by random amplified polymorphic DNA （ RAPD） technique. The results showed that the similar coefficient o...The intra-population phylogenetic relationship between Micropterus salmoides and Tilapia nilotica was analyzed by random amplified polymorphic DNA （ RAPD） technique. The results showed that the similar coefficient of bands between M. salmoides and T. nilotica was 0.236, and the genetic distance was 0. 764, which indicated that M. salmoides had a distant relationship with T. nilotica.展开更多
As one of the most important aquatic fish,Micropterus salmoides suffers lethal and epidemic disease caused by rhabdovirus at the juvenile stage.In this study,a new strain of M.salmoides rhabdovirus(MSRV)was isolated f...As one of the most important aquatic fish,Micropterus salmoides suffers lethal and epidemic disease caused by rhabdovirus at the juvenile stage.In this study,a new strain of M.salmoides rhabdovirus(MSRV)was isolated from Yuhang,Zhejiang Province,China,and named MSRV-YH01.The virus infected the grass carp ovary(GCO)cell line and displayed virion particles with atypical bullet shape,300–500 nm in length and 100–200 nm in diameter under transmission electron microscopy.The complete genome sequence of this isolate was determined to include 11 526 nucleotides and to encode five classical structural proteins.The construction of the phylogenetic tree indicated that this new isolate is clustered into the Vesiculovirus genus and most closely related to the Siniperca chuatsi rhabdovirus.To explore the potential for a vaccine against MSRV,a glycoprotein(1–458 amino acid residues)of MSRV-YH01 was successfully amplified and cloned into the plasmid pFastBac1.The high-purity recombinant bacmid-glycoprotein was obtained from DH10Bac through screening and identification.Based on polymerase chain reaction(PCR),western blot,and immunofluorescence assay,recombinant virus,including the MSRV-YH01 glycoprotein gene,was produced by transfection of SF9 cells using the pFastBac1-gE2,and then repeatedly amplified to express the glycoprotein protein.We anticipate that this recombinant bacmid system could be used to challenge the silkworm and develop a corresponding oral vaccine for fish.展开更多
This work evaluates the application potential of a new indigenous aerobic denitrifi er, strain Pseudomonas CW-2, isolated from a largemouth bass culture pond. The rate of ammonium-N removal by strain CW-2 was approxim...This work evaluates the application potential of a new indigenous aerobic denitrifi er, strain Pseudomonas CW-2, isolated from a largemouth bass culture pond. The rate of ammonium-N removal by strain CW-2 was approximately 97% at a DO concentration of 5.2 mg/L. Furthermore, when nitrate and ammonia coexisted, the strain gave priority to assimilating ammonia, and thereafter to denitrifi cation. Under optimal cultivation conditions, citrate and acetate were the carbon resources, C/N was 8, dissolved oxygen was 5.2 mg/L, and pH was 7; the removal rate of ammonium reached nearly 90%. The changing patterns of different bacteria in strain CW-2-treated and the control pond water were also compared. Lower levels of ammonia, nitrite, and phosphates were observed in the treated water as compared with the controls. Meanwhile, phylum-level distributions of the bacterial OTUs revealed that P roteobacteria, Bacteroidetes, Planctomycetes, and N itrospirae continuously changed their relative abundances in relation to carbon and the addition of strain CW-2; this finding implies that the conventional denitrifi cation process was weakened under the ef fects of carbon or the presence of strain CW-2. We propose that strain CW-2 is a promising organism for the removal of ammonium in intensive fish culture systems, according to our evaluations of its denitrifi cation performance.展开更多
Aeromonas hydrophila is a Gram-negative pathogen that can infect various fish,including largemouth bass(Micropterus salmoides),which have caused huge economic losses.In present study,largemouth bass anti-A.hydrophila ...Aeromonas hydrophila is a Gram-negative pathogen that can infect various fish,including largemouth bass(Micropterus salmoides),which have caused huge economic losses.In present study,largemouth bass anti-A.hydrophila antibodies were produced,then a highly immunogenic outer membrane proteins,AHA_3793,was identified by combined western blotting and mass spectrometry analysis.Moreover,AHA_3793 was expressed,and its immunogenicity was further verified by western blotting.Subsequently,the protective efficacy of AHA_3793 were evaluated in largemouth bass.The results showed that rAHA_3793 could produce a relative percentage survival(RPS)of 61.76% for largemouth bass against A.hydrophila challenge.ELISA analysis showed the specific serum antibodies of largemouth bass against rAHA_3793 and A.hydrophila in vaccinated group in weeks 4 and 5 after immunization were significantly higher than those in control group,which suggested that rAHA_3793 induced production of specific serum antibodies against rAHA_3793 and A.hydrophila.The qRT-PCR analysis showed that expressions of CD4-2 and MHC Ⅱα were also significantly up-regulated after immunization.These results collectively demonstrated that rAHA_3793 could induce a strong humoral immune response of largemouth bass,and then produce high immune protection ef fects against A.hydrophila infection.展开更多
Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different...Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.展开更多
Largemouth bass have been plagued by diseases elicited by bacteria,parasites,and viruses,particularly viral diseases,which have caused significant economic losses in recent years.And there is a lack of approved antivi...Largemouth bass have been plagued by diseases elicited by bacteria,parasites,and viruses,particularly viral diseases,which have caused significant economic losses in recent years.And there is a lack of approved antiviral drugs in the aquaculture industry.Micropterus salmoides Rhabdovirus(MSRV)is the causative agent of Micro-pterus salmoides Rhabdovirus disease,which mostly affects largemouth bass fry.By using experimental infection,transcriptome sequencing,and inhibitor treatment,the inflammatory response mediated by mitogen-activated protein kinase(MAPK),phosphatidylinositol3-kinase(PI3K),and nuclear factor kappa-B(NF-κB)pathways was verified as one of the pathological processes of MSRV infection.Further,Myricetin,arteannuin,naringenin,ursolic acid,andrographolide,and resveratrol were selected to evolute their anti-inflammatory activity based on the promoter of NF-κB and found myricetin,naringenin,andrographolide,and resveratrol significantly inhibited NF-κB 1 promoter activity.Myricetin was found to damp MSRV caused-inflammation and inhibit MSRV infection by suppressing NF-κB signaling.Besides,myricetin improves the survival rate of largemouth bass after MSRV infection.In conclusion,myricetin presented anti-MSRV activity by targeting the NF-κB inflammatory pathway and can be further developed as a potential preventative drug of rhabdovirus disease.展开更多
Blunt snout bream(Megalobrama amblycephala)and largemouth bass(Micropterus salmoides)are a herbivorous and a carnivorous freshwater fish species respectively.These fish possess distinct intestinal microorganisms and d...Blunt snout bream(Megalobrama amblycephala)and largemouth bass(Micropterus salmoides)are a herbivorous and a carnivorous freshwater fish species respectively.These fish possess distinct intestinal microorganisms and digestive enzymes that play a vital role in nutrient digestion.As a result,herbivorous and carnivorous fish exhibit significant differences in their digestive strategies.In this study,we investigated the compositions and functions of the gut flora of herbivorous M.amblycephala and carnivorous M.salmoides by 16S rRNA sequencing.PCoA analysis revealed that the gut flora of M.amblycephala and M.salmoides formed two distinct clusters.OTU analysis found that M.amblycephala and M.salmoides shared a small number,but high abundance,of core mi-croorganisms,and that a large number of microorganisms differed at the phylum and genus levels between the two species.The cellulose-degrading bacteria Longivirga,Flavobacterium,Clostridium_sensu_stricto_12,and Bacillus were dominant in M.amblycephala,while protein-degrading bacteria Clostridium_sensu_stricto_1,Lactococcus,Streptococcus and Proteiniclasticum were dominant in M.salmoides.PICRUSt analysis showed significant differ-ences in carbohydrate and protein metabolism functions as well.In addition,cellulase and amylase activities were significantly higher in M.amblycephala than in M.salmoides,while trypsin activity was significantly higher in M.salmoides than in M.amblycephala.These results indicated that dietary patterns influenced the composition and function of the bacterial community and the activity of digestive enzymes in the host's gut.展开更多
The largemouth bass virus(LMBV)exhibits high pathogenicity in both adult and juvenile largemouth bass,causing substantial economic losses within the aquaculture industry.MicroRNAs(miRNAs)are crucial in con-trolling vi...The largemouth bass virus(LMBV)exhibits high pathogenicity in both adult and juvenile largemouth bass,causing substantial economic losses within the aquaculture industry.MicroRNAs(miRNAs)are crucial in con-trolling viral infections and the host's immune responses,making them significantly valuable in the treatment and diagnosis of diseases.Nevertheless,research on miRNA expression profiles associated with LMBV infection in largemouth bass is currently insufficient.This research attempts to investigate the roles and molecular mecha-nisms of miRNAs in the potential immune response and metabolic alterations triggered by LMBV infection in largemouth bass using miRNA sequencing.Following quality screening,the infection group and control group yielded a combined total of 142.73 million clean reads,with lengths predominantly at 22 nt.1718 known miRNAs were identified,including 238 differentially expressed miRNAs(DEMs).In addition,400 novel miRNAs were predicted,36 of which were DEMs.To gain further insight into the immune and metabolic related biological functions of DEMs,target gene prediction was conducted.KEGG pathway analysis revealed that LMBV impacted pathways such as Endocytosis,Purine metabolism,Phosphatidylinositol,Fatty acid Biosynthesis,and Phagosome signaling systems,highlighting the vital role of miRNAs in immune responses and metabolicalterations.Furthermore,the miRNA-mRNAinteraction network revealed crucial miRNAs and their correspondingtarget genes involved in conferring resistance against viral infections by utilizing metabolicand immune related pathways as the foundation.Ten DEMs were selected at random for real-time quantitative PCR(qRT-PCR),and results exhibited expression patterns that were consistent with sequencing data.These findings validate the im-mune and metabolic regulatory function of miRNAs against LMBV in largemouth bass,offering valuable per-spectives for the prevention and management of illnesses linked to iridoviruses.展开更多
Hermetia illucens(HI)meal is a promising substitute for fish meal(FM)in the feeds of farmed fish.However,the impacts of dietary HI meal on largemouth bass(LMB)remain unknown.In this study,we formulated three isonitrog...Hermetia illucens(HI)meal is a promising substitute for fish meal(FM)in the feeds of farmed fish.However,the impacts of dietary HI meal on largemouth bass(LMB)remain unknown.In this study,we formulated three isonitrogenous and isolipid diets with 0%(HI0,control),20%(H120)and 40%(HI40)of FM substituted by HI meal.A total of 270 juvenile largemouth bass with an initial body weight of 10.02±0.03 g were used(30 fish per tank).After an 80-day feeding trial,the fish fed with the HI40 diet demonstrated decreased growth performance and protein efficiency ratio(PER),and increased liver oxidative indices and lipid accumulation compared to the control(P<0.05).Transcriptomic analysis revealed the effects of high dietary HI meal on liver gene expression.Consistent with the reduced growth and disturbed liver oxidative status,the upregulated genes were enriched in the biological processes associated with protein catabolism and endoplasmic reticulum(ER)stress;while the downregulated genes were enriched in cellular proliferation,growth,metabolism,immunity and maintenance of tissue homeostasis.Differential metabolites in the liver samples were also identified by untargeted metab-olomic assay.The results of joint transcriptomic-metabolomic analyses revealed that the pathways such as one carbon pool by folate,propanoate metabolism and alpha-linolenic acid metabolism were disturbed by high dietary HI meal.In summary,our data revealed the candidate genes,metabolites and biological pathways that account for the adverse effects of high HI meal diet on the growth and health of LMB.展开更多
The study aimed to assess the effects of dietary black soldier fly oil(BSFO)on the growth performance,flesh quality,and health status of largemouth bass(Micropterus salmoides).Six iso-nitrogenous and isolipid diets we...The study aimed to assess the effects of dietary black soldier fly oil(BSFO)on the growth performance,flesh quality,and health status of largemouth bass(Micropterus salmoides).Six iso-nitrogenous and isolipid diets were formulated by substituting fish oil and soybean oil(1/2,wt/wt)with BSFO in percentages of 0%,20%,40%,60%,80%,and 100%,respectively.The diets were fed to 960 fish(initial body weight=16.5 g)in four replicates for 8 weeks.Indicators related to growth performance,body composition,hematology,flesh quality,expression of genes related to inflammatory cytokines and apoptosis,and the response of fish to Aeromonas veronii challenge were analyzed.The results showed that the weight gain rate was numerically improved in all BSFO substitution groups,ranging from 9.3%to 44.0%compared to the control group.The highest survival rate and the lowest hepatosomatic index and condition factor were observed in the BFSO20 group.In terms of flesh quality,the water-holding capacity of the dorsal muscle was elevated with higher levels of dietary BSFO.However,significant changes in texture properties(cohesiveness,gluing,and chewiness)were observed in the BSFO20 group(P<0.05).Six hematological parameters related to glycolipid and liver function were optimized in most of the BFSO substitution groups.Furthermore,the expressions of six inflammation-and apoptosis-related genes(IL-1β,Bcl-xl,BAX,caspase8,TNF-α,and IL-10)were significantly affected by dietary BSFO(P<0.05).Following bacterial challenge,the seven-day cumulative survival rates of fish were considerably increased from 10.0%in the control group to 60.0%and 66.7%in the BSFO80 and BSFO100 groups,respectively.One-variable linear regression analysis revealed that various parameters related to fish growth,flesh quality,and health status were significantly influenced by dietary BSFO substitution levels in a dose-dependent manner(P<0.05).In conclusion,substituting around 20%of dietary fish oil and soybean oil with BSFO is promising in improving the growth performance and flesh quality of M.salmoides.However,to enhance immunity and disease resistance,it is recommended to further increase the inclusion of BSFO in the diet.展开更多
Chlorella meal is a potential protein source for aquafeeds.However,the physiological response of carnivorous fish fed Chlorella meal remains elusive.This study evaluated the effects of replacing dietary fish meal with...Chlorella meal is a potential protein source for aquafeeds.However,the physiological response of carnivorous fish fed Chlorella meal remains elusive.This study evaluated the effects of replacing dietary fish meal with Chlorella meal on growth performance,pigmentation,and liver health in largemouth bass.Five diets were formulated to replace dietary fish meal of 0%(C0,control),25%(C25),50%(C50),75%(C75),and 100%(C100)with Chlorella meal,respectively.Total 300 fish(17.6±0.03 g)were randomly assigned to 15 tanks(3 tanks/group).Fish were fed the experimental diet twice daily for 8 weeks.The increased dietary Chlorella meal quadratically influenced the final body weight(FBW),weight gain rate(WGR),specific growth rate(SGR),and feed intake(FI),which were significantly lower in the C100 group than in the other groups(P<0.05).The feed conversion ratio(FCR)increased linearly or quadratically with dietary Chlorella meal.Dietary Chlorella meal linearly or quadratically increased the lutein content of plasma,liver,and dorsal muscle of largemouth bass(P<0.05).Compared to the C0 group,all supplemented Chlorella meal groups significantly improved the yellowness(b*)of the dorsal body(1.5 to 2.0 fold),abdominal body(1.5 to 1.8 fold),and dorsal muscle(3.8 to 5.4 fold)of largemouth bass(P<0.05).In addition,compared to the C0 group,the liver vacuolation area of fish was significantly increased in the C75 and C100 groups(P<0.05).Transcriptional levels of apoptosis-related genes of b-cell lymphoma-2(bcl2),caspase-9-like(casp9),and caspase-3a(casp3)were markedly upregulated(0.9 to 1.6 fold)in the C100 group compared to the C0 group(P<0.05).Based on the quadratic regression analysis between FBW,WGR,or SGR and dietary Chlorella meal level,largemouth bass had the best growth when replacing 31.7%to 32.6%of fish meal with 15.03%to 15.43%dietary Chlorella meal.The present results indicated that dietary supplementation with Chlorella meal(11.85%to 47.45%)significantly enhanced the pigmentation;however,total replacement of fish meal(40%)with Chlorella meal(47.45%)caused growth retardation,apoptosis,and liver damage in largemouth bass.展开更多
Clostridium autoethanogenum protein(CAP)is a new single-cell protein source originating from inactivated bacteria.An in vitro digestion experiment and an 8-wk growth experiment were conducted to evaluate the molecular...Clostridium autoethanogenum protein(CAP)is a new single-cell protein source originating from inactivated bacteria.An in vitro digestion experiment and an 8-wk growth experiment were conducted to evaluate the molecular weight distribution of the CAP hydrolysate,and the effects of dietary CAP levels on the growth performance,plasma parameters,hepatic and intestinal health,and the diversity of gutadherent microbiota of largemouth bass(Micropterus salmoides).The fish(initial body weight of 47.99±0.01 g)were fed diets where CAP gradually replaced 0%(CAP0),12.5%(CAP12.5),25%(CAP25),37.5%(CAP37.5)and 50%(CAP50)of low-temperature steam dried anchovy fish meal(LTFM)in the diet.Results showed that the content of peptides below 1,000 Da in the CAP hydrolysate(0.56 mg/mL)was higher than that of the LTFM hydrolysate(0.48 mg/mL).Dietary CAP inclusion had no negative effect on growth performance,while whole-body lipid content significantly reduced in the CAP25 and CAP50 groups(P<0.05).The plasma alanine aminotransferase activities and triglyceride concentrations in the CAP inclusion groups were significantly lower than those in the CAP0 group(P<0.05).The plasma aspartate aminotransferase activity was significantly reduced in the CAP37.5 group(P<0.05).The richness and diversity of the gut-adhesive microbiota and the proportion of Clostridium sensu stricto 12 in the CAP50 group were significantly higher than those in the CAP0 group(P<0.05).Dietary CAP inclusion inhibited inflammatory responses by down-regulating the mRNA levels of interleukin 1b(IL1b),IL10 and transforming growth factor b1(P<0.05)in the liver.The mRNA levels of acetyl-CoA carboxylase 1 were significantly down-regulated in the CAP12.5,CAP25 and CAP37.5 groups(P<0.05),while that of fatty acid synthase was significantly down-regulated in the CAP50 group(P<0.05).These results demonstrate that dietary CAP inclusion could improve the hepatic and intestinal health of largemouth bass,and can be helpful to further develop CAP as a functional feed ingredient.展开更多
Cottonseed protein concentrate is a sustainable fishmeal alternative in aquafeed.A 10-week experiment was conducted to investigate the effects of a cottonseed protein concentrate-based diet with and without multi-stra...Cottonseed protein concentrate is a sustainable fishmeal alternative in aquafeed.A 10-week experiment was conducted to investigate the effects of a cottonseed protein concentrate-based diet with and without multi-strain yeast fractions(MsYF)on growth,bile acid metabolism,and health in largemouth bass.Four hundred fish(54.0±0.0 g)were casually distributed into 16 tanks(4 replicates/diet).Fish were fed with 4 iso-nitrogen and iso-energetic diets 3 times daily,including a fishmeal diet(FM),a soy protein concentrate-based diet(SPC;replacing 81%fishmeal protein),a cottonseed protein concentrate-based diet(CPC;replacing 81%fishmeal protein),and a CPC diet supplemented with 800 mg/kg MsYF(CPCY).Results showed that the survival of SPC was the lowest,i.e.,48%,with no apparent diet effect among other treatments;we omitted the SPC in additional analyses.Fish fed cottonseed protein concentrate-based diets showed lower growth than FM(P<0.05).Fish fed CPC showed the highest nuclear dense hepatic phenotypes ratio(50%),followed by CPCY(33%)and FM(17%).Further,dietary CPC increased hepatic total cholesterol and triglyceride levels with concurrently increased cholesterol syn-thesis but decreased triglyceride synthesis-associated transcription levels(P<0.05).Furthermore,di-etary CPC increased bile acid synthesis but decreased bile acid transport-associated transcription levels(P<0.05),and then induced an increment of plasma cholic acid and hepatic chenodeoxycholic acid content and the decrement of genus Romboustia(P<0.05).Regarding the effect of MsYF,fish fed CPCY reduced hepatic lipid accumulation and total plasma bile acid content(P<0.05)compared to CPC,suggesting an improvement in liver health.Also,dietary MsYF could reverse the microbiota community structure showing a similar gut microbial composition to FM.In conclusion,81%of fishmeal protein replaced by cottonseed protein concentrate suppressed growth and liver health,while dietary MsYF might mitigate the negative impact of a high cottonseed protein concentrate level diet on liver functions via gut microbiota regulation.展开更多
This study was conducted to evaluate the influence of dietary lysophospholipids combined with 1%dietary fish oil reduction on the growth performance and hepatic lipid metabolism of largemouth bass(Micropterus salmoide...This study was conducted to evaluate the influence of dietary lysophospholipids combined with 1%dietary fish oil reduction on the growth performance and hepatic lipid metabolism of largemouth bass(Micropterus salmoides).Five isonitrogenous feeds were prepared with lysophospholipids at 0%(fish oil group,FO),0.05%(L-0.05),0.1%(L-0.1),0.15%(L-0.15)and 0.2%(L-0.2),respectively.The dietary lipid was 11%in the FO diet and 10%in the other diets.Largemouth bass were fed for 68 d(initial body weight=6.04±0.01 g)with 4 replicates per group and 30 fish per replicate.The results showed that the fish fed diet containing 0.1%lysophospholipids had higher digestive enzyme activity and obtained better growth performance compared to the fish fed FO diet(P<0.05).The feed conversion rate in the L-0.1 group was significantly lower than that in the other groups.Serum total protein and triglyceride contents in L-0.1 group were significantly higher than those in other groups(P<0.05)and the contents of total cholesterol and low-density lipoprotein cholesterol in L-0.1 group were significantly lower than those in FO group(P<0.05).The activity and genes expression of hepatic glucolipid metabolizing enzymes in L-0.15 group were significantly increased compared to those in FO group(P<0.05).Reducing 1%fish oil along with 0.1%lysophospholipids added to the feed could improve the digestion and absorption of nutrients,enhance the activity of liver glycolipid metabolizing enzymes,and thus effectively promote the growth of largemouth bass.展开更多
基金Supported by the Scientific Fund of Jiangsu Province(No.BY2015039-10)the Aquatic Three Project of Jiangsu Province(No.Y2017-37)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)the Jiangsu Funding Program for Excellent Postdoctoral Talent。
文摘Heat stress(HS)has been shown to adversely affect fish livers and can lead to extensive apoptosis.To investigate the relationship between endoplasmic reticulum(ER)stress and HS-induced apoptosis in fish livers,we isolated and cultured primary hepatocytes of largemouth bass,Micropterus salmoides by trypsin method,then established an in-vitro model of liver cells under HS(35℃).The contents of lactic dehydrogenase(LDH)and hydrogen peroxide(H2O2)were determined to evaluate the effects of HS on hepatocyte injury and oxidative stress.RT-qPCR was performed to discover the key genes in unfolded protein response(UPR)pathways involved at different HS duration.ERS inhibitor 4-PBA and IRE1αinhibitor 4μ8C were used to further investigate the effects of HS on IRE1αapoptosis pathway in hepatocytes.Results show that HS led to significant increases in the release of LDH,the content of H2O2,and the expressions of oxidative protein folding genes(ero1αand pdi)under HS,suggesting severe hepatocyte injury and oxidative stress happened in heat-stressed largemouth bass hepatocytes.The continuous activation of IRE1αpathway genes(grp78,grp94,atf6,perk,eif2a,atf4,chop,ire1α,traf2,ask1,jnk1,and jnk2)indicated that HS led significantly to ER stress.In particular,the mRNA expression levels of ER stress-related genes(grp78,grp94,atf6,perk,ire1α,chop,jnk1,and jnk2)in the high temperature(HT)+4-PBA group and the HT+4μ8C group were significantly down-regulated under HS.After 4μ8C treatment,the expression levels of apoptosis-related genes(caspase-2,caspase-3,caspase-6,caspase-7,caspase-8,caspase-9,and caspase-10)and LDH content were significantly decreased,whereas the cell survival rate was significantly increased when given 4-PBA or 4μ8C treatment.These findings demonstrate that HS could induce liver apoptosis of largemouth bass through the IRE1αpathway,which may act as a key switch mediating liver apoptosis of largemouth bass under HS.
文摘The intra-population phylogenetic relationship between Micropterus salmoides and Tilapia nilotica was analyzed by random amplified polymorphic DNA （ RAPD） technique. The results showed that the similar coefficient of bands between M. salmoides and T. nilotica was 0.236, and the genetic distance was 0. 764, which indicated that M. salmoides had a distant relationship with T. nilotica.
文摘As one of the most important aquatic fish,Micropterus salmoides suffers lethal and epidemic disease caused by rhabdovirus at the juvenile stage.In this study,a new strain of M.salmoides rhabdovirus(MSRV)was isolated from Yuhang,Zhejiang Province,China,and named MSRV-YH01.The virus infected the grass carp ovary(GCO)cell line and displayed virion particles with atypical bullet shape,300–500 nm in length and 100–200 nm in diameter under transmission electron microscopy.The complete genome sequence of this isolate was determined to include 11 526 nucleotides and to encode five classical structural proteins.The construction of the phylogenetic tree indicated that this new isolate is clustered into the Vesiculovirus genus and most closely related to the Siniperca chuatsi rhabdovirus.To explore the potential for a vaccine against MSRV,a glycoprotein(1–458 amino acid residues)of MSRV-YH01 was successfully amplified and cloned into the plasmid pFastBac1.The high-purity recombinant bacmid-glycoprotein was obtained from DH10Bac through screening and identification.Based on polymerase chain reaction(PCR),western blot,and immunofluorescence assay,recombinant virus,including the MSRV-YH01 glycoprotein gene,was produced by transfection of SF9 cells using the pFastBac1-gE2,and then repeatedly amplified to express the glycoprotein protein.We anticipate that this recombinant bacmid system could be used to challenge the silkworm and develop a corresponding oral vaccine for fish.
基金Supported by the National Key Technology R&D Program of China(Nos.2012BAD25B04,2012BAD25B01)the Earmarked Fund for Modern Agro-Industry Technology Research System(No.CARS-46-17)+2 种基金the National Natural Science Foundation of China(No.31302201)the Pearl River S&T Nova Program of Guangzhou(No.2014J2200088)the Science and Technology Program of Guangzhou(No.201707010311)
文摘This work evaluates the application potential of a new indigenous aerobic denitrifi er, strain Pseudomonas CW-2, isolated from a largemouth bass culture pond. The rate of ammonium-N removal by strain CW-2 was approximately 97% at a DO concentration of 5.2 mg/L. Furthermore, when nitrate and ammonia coexisted, the strain gave priority to assimilating ammonia, and thereafter to denitrifi cation. Under optimal cultivation conditions, citrate and acetate were the carbon resources, C/N was 8, dissolved oxygen was 5.2 mg/L, and pH was 7; the removal rate of ammonium reached nearly 90%. The changing patterns of different bacteria in strain CW-2-treated and the control pond water were also compared. Lower levels of ammonia, nitrite, and phosphates were observed in the treated water as compared with the controls. Meanwhile, phylum-level distributions of the bacterial OTUs revealed that P roteobacteria, Bacteroidetes, Planctomycetes, and N itrospirae continuously changed their relative abundances in relation to carbon and the addition of strain CW-2; this finding implies that the conventional denitrifi cation process was weakened under the ef fects of carbon or the presence of strain CW-2. We propose that strain CW-2 is a promising organism for the removal of ammonium in intensive fish culture systems, according to our evaluations of its denitrifi cation performance.
基金Supported by the National Natural Science Foundation of China(No.32102824)the Zhejiang Provincial Natural Science Foundation of China(No.LQ18B060005)the Zhejiang Sci-Tech University Foundation(Nos.11612932611702,11612832611909)。
文摘Aeromonas hydrophila is a Gram-negative pathogen that can infect various fish,including largemouth bass(Micropterus salmoides),which have caused huge economic losses.In present study,largemouth bass anti-A.hydrophila antibodies were produced,then a highly immunogenic outer membrane proteins,AHA_3793,was identified by combined western blotting and mass spectrometry analysis.Moreover,AHA_3793 was expressed,and its immunogenicity was further verified by western blotting.Subsequently,the protective efficacy of AHA_3793 were evaluated in largemouth bass.The results showed that rAHA_3793 could produce a relative percentage survival(RPS)of 61.76% for largemouth bass against A.hydrophila challenge.ELISA analysis showed the specific serum antibodies of largemouth bass against rAHA_3793 and A.hydrophila in vaccinated group in weeks 4 and 5 after immunization were significantly higher than those in control group,which suggested that rAHA_3793 induced production of specific serum antibodies against rAHA_3793 and A.hydrophila.The qRT-PCR analysis showed that expressions of CD4-2 and MHC Ⅱα were also significantly up-regulated after immunization.These results collectively demonstrated that rAHA_3793 could induce a strong humoral immune response of largemouth bass,and then produce high immune protection ef fects against A.hydrophila infection.
基金Supported by Key R&D Program of Hubei Province(2022BBA0058)。
文摘Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.
基金supported by the National Natural Science Foundation of China(31872598)China Agriculture Research System(CARS-46).
文摘Largemouth bass have been plagued by diseases elicited by bacteria,parasites,and viruses,particularly viral diseases,which have caused significant economic losses in recent years.And there is a lack of approved antiviral drugs in the aquaculture industry.Micropterus salmoides Rhabdovirus(MSRV)is the causative agent of Micro-pterus salmoides Rhabdovirus disease,which mostly affects largemouth bass fry.By using experimental infection,transcriptome sequencing,and inhibitor treatment,the inflammatory response mediated by mitogen-activated protein kinase(MAPK),phosphatidylinositol3-kinase(PI3K),and nuclear factor kappa-B(NF-κB)pathways was verified as one of the pathological processes of MSRV infection.Further,Myricetin,arteannuin,naringenin,ursolic acid,andrographolide,and resveratrol were selected to evolute their anti-inflammatory activity based on the promoter of NF-κB and found myricetin,naringenin,andrographolide,and resveratrol significantly inhibited NF-κB 1 promoter activity.Myricetin was found to damp MSRV caused-inflammation and inhibit MSRV infection by suppressing NF-κB signaling.Besides,myricetin improves the survival rate of largemouth bass after MSRV infection.In conclusion,myricetin presented anti-MSRV activity by targeting the NF-κB inflammatory pathway and can be further developed as a potential preventative drug of rhabdovirus disease.
基金supported by the National Natural Science Foundation of China(32273109)Hubei Provincial Natural Science Foundation of China(2022CFB106)+1 种基金the China Agriculture Research System of MOF and MARA(No.CARS-45-01)Wuhan Biological Breeding Special Project(2022021302024854).
文摘Blunt snout bream(Megalobrama amblycephala)and largemouth bass(Micropterus salmoides)are a herbivorous and a carnivorous freshwater fish species respectively.These fish possess distinct intestinal microorganisms and digestive enzymes that play a vital role in nutrient digestion.As a result,herbivorous and carnivorous fish exhibit significant differences in their digestive strategies.In this study,we investigated the compositions and functions of the gut flora of herbivorous M.amblycephala and carnivorous M.salmoides by 16S rRNA sequencing.PCoA analysis revealed that the gut flora of M.amblycephala and M.salmoides formed two distinct clusters.OTU analysis found that M.amblycephala and M.salmoides shared a small number,but high abundance,of core mi-croorganisms,and that a large number of microorganisms differed at the phylum and genus levels between the two species.The cellulose-degrading bacteria Longivirga,Flavobacterium,Clostridium_sensu_stricto_12,and Bacillus were dominant in M.amblycephala,while protein-degrading bacteria Clostridium_sensu_stricto_1,Lactococcus,Streptococcus and Proteiniclasticum were dominant in M.salmoides.PICRUSt analysis showed significant differ-ences in carbohydrate and protein metabolism functions as well.In addition,cellulase and amylase activities were significantly higher in M.amblycephala than in M.salmoides,while trypsin activity was significantly higher in M.salmoides than in M.amblycephala.These results indicated that dietary patterns influenced the composition and function of the bacterial community and the activity of digestive enzymes in the host's gut.
基金funded by Natural Science Foundation of Hubei Province (2022CFB859)the Jiangsu Agriculture Science and Technology Innovation Found (CX (24) 3066)+1 种基金China postdoctoral Science Foundation (2021M702761)the Open Project of International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China (5),‘Blue Project’ of Yangzhou University.
文摘The largemouth bass virus(LMBV)exhibits high pathogenicity in both adult and juvenile largemouth bass,causing substantial economic losses within the aquaculture industry.MicroRNAs(miRNAs)are crucial in con-trolling viral infections and the host's immune responses,making them significantly valuable in the treatment and diagnosis of diseases.Nevertheless,research on miRNA expression profiles associated with LMBV infection in largemouth bass is currently insufficient.This research attempts to investigate the roles and molecular mecha-nisms of miRNAs in the potential immune response and metabolic alterations triggered by LMBV infection in largemouth bass using miRNA sequencing.Following quality screening,the infection group and control group yielded a combined total of 142.73 million clean reads,with lengths predominantly at 22 nt.1718 known miRNAs were identified,including 238 differentially expressed miRNAs(DEMs).In addition,400 novel miRNAs were predicted,36 of which were DEMs.To gain further insight into the immune and metabolic related biological functions of DEMs,target gene prediction was conducted.KEGG pathway analysis revealed that LMBV impacted pathways such as Endocytosis,Purine metabolism,Phosphatidylinositol,Fatty acid Biosynthesis,and Phagosome signaling systems,highlighting the vital role of miRNAs in immune responses and metabolicalterations.Furthermore,the miRNA-mRNAinteraction network revealed crucial miRNAs and their correspondingtarget genes involved in conferring resistance against viral infections by utilizing metabolicand immune related pathways as the foundation.Ten DEMs were selected at random for real-time quantitative PCR(qRT-PCR),and results exhibited expression patterns that were consistent with sequencing data.These findings validate the im-mune and metabolic regulatory function of miRNAs against LMBV in largemouth bass,offering valuable per-spectives for the prevention and management of illnesses linked to iridoviruses.
基金supported by the National Key R&D Program of China(2019YFD0900200)Chongqing Ecological Fishery Technology System,China(2023)and Chongqing fishery technology innovation union(CQFTIU2022-05).
文摘Hermetia illucens(HI)meal is a promising substitute for fish meal(FM)in the feeds of farmed fish.However,the impacts of dietary HI meal on largemouth bass(LMB)remain unknown.In this study,we formulated three isonitrogenous and isolipid diets with 0%(HI0,control),20%(H120)and 40%(HI40)of FM substituted by HI meal.A total of 270 juvenile largemouth bass with an initial body weight of 10.02±0.03 g were used(30 fish per tank).After an 80-day feeding trial,the fish fed with the HI40 diet demonstrated decreased growth performance and protein efficiency ratio(PER),and increased liver oxidative indices and lipid accumulation compared to the control(P<0.05).Transcriptomic analysis revealed the effects of high dietary HI meal on liver gene expression.Consistent with the reduced growth and disturbed liver oxidative status,the upregulated genes were enriched in the biological processes associated with protein catabolism and endoplasmic reticulum(ER)stress;while the downregulated genes were enriched in cellular proliferation,growth,metabolism,immunity and maintenance of tissue homeostasis.Differential metabolites in the liver samples were also identified by untargeted metab-olomic assay.The results of joint transcriptomic-metabolomic analyses revealed that the pathways such as one carbon pool by folate,propanoate metabolism and alpha-linolenic acid metabolism were disturbed by high dietary HI meal.In summary,our data revealed the candidate genes,metabolites and biological pathways that account for the adverse effects of high HI meal diet on the growth and health of LMB.
基金supported by Key project of Research and Development Programme of Guangdong Province (2021B0202050002)Project of Guangdong Province Guiding Local Science and Technology Devel opment (GS202331)Open Project of Guangdong Provincial Key Laboratory of Animal Breeding and Nutrition Research (2022SZ05).
文摘The study aimed to assess the effects of dietary black soldier fly oil(BSFO)on the growth performance,flesh quality,and health status of largemouth bass(Micropterus salmoides).Six iso-nitrogenous and isolipid diets were formulated by substituting fish oil and soybean oil(1/2,wt/wt)with BSFO in percentages of 0%,20%,40%,60%,80%,and 100%,respectively.The diets were fed to 960 fish(initial body weight=16.5 g)in four replicates for 8 weeks.Indicators related to growth performance,body composition,hematology,flesh quality,expression of genes related to inflammatory cytokines and apoptosis,and the response of fish to Aeromonas veronii challenge were analyzed.The results showed that the weight gain rate was numerically improved in all BSFO substitution groups,ranging from 9.3%to 44.0%compared to the control group.The highest survival rate and the lowest hepatosomatic index and condition factor were observed in the BFSO20 group.In terms of flesh quality,the water-holding capacity of the dorsal muscle was elevated with higher levels of dietary BSFO.However,significant changes in texture properties(cohesiveness,gluing,and chewiness)were observed in the BSFO20 group(P<0.05).Six hematological parameters related to glycolipid and liver function were optimized in most of the BFSO substitution groups.Furthermore,the expressions of six inflammation-and apoptosis-related genes(IL-1β,Bcl-xl,BAX,caspase8,TNF-α,and IL-10)were significantly affected by dietary BSFO(P<0.05).Following bacterial challenge,the seven-day cumulative survival rates of fish were considerably increased from 10.0%in the control group to 60.0%and 66.7%in the BSFO80 and BSFO100 groups,respectively.One-variable linear regression analysis revealed that various parameters related to fish growth,flesh quality,and health status were significantly influenced by dietary BSFO substitution levels in a dose-dependent manner(P<0.05).In conclusion,substituting around 20%of dietary fish oil and soybean oil with BSFO is promising in improving the growth performance and flesh quality of M.salmoides.However,to enhance immunity and disease resistance,it is recommended to further increase the inclusion of BSFO in the diet.
基金National Natural Science Foundation of China(U21A20266,31972771,31972805,31672670)China Agriculture Research System of MOF and MARA(CARS-46)+2 种基金National Key R&D Program of China(2018YFD0900400)Fund Project in State Key Laboratory of Freshwater Ecology and Biotechnology(2019FBZ02,2019FBZ05)Hubei High-tech Innovation and Business Incubation Center(2019-02-055).
文摘Chlorella meal is a potential protein source for aquafeeds.However,the physiological response of carnivorous fish fed Chlorella meal remains elusive.This study evaluated the effects of replacing dietary fish meal with Chlorella meal on growth performance,pigmentation,and liver health in largemouth bass.Five diets were formulated to replace dietary fish meal of 0%(C0,control),25%(C25),50%(C50),75%(C75),and 100%(C100)with Chlorella meal,respectively.Total 300 fish(17.6±0.03 g)were randomly assigned to 15 tanks(3 tanks/group).Fish were fed the experimental diet twice daily for 8 weeks.The increased dietary Chlorella meal quadratically influenced the final body weight(FBW),weight gain rate(WGR),specific growth rate(SGR),and feed intake(FI),which were significantly lower in the C100 group than in the other groups(P<0.05).The feed conversion ratio(FCR)increased linearly or quadratically with dietary Chlorella meal.Dietary Chlorella meal linearly or quadratically increased the lutein content of plasma,liver,and dorsal muscle of largemouth bass(P<0.05).Compared to the C0 group,all supplemented Chlorella meal groups significantly improved the yellowness(b*)of the dorsal body(1.5 to 2.0 fold),abdominal body(1.5 to 1.8 fold),and dorsal muscle(3.8 to 5.4 fold)of largemouth bass(P<0.05).In addition,compared to the C0 group,the liver vacuolation area of fish was significantly increased in the C75 and C100 groups(P<0.05).Transcriptional levels of apoptosis-related genes of b-cell lymphoma-2(bcl2),caspase-9-like(casp9),and caspase-3a(casp3)were markedly upregulated(0.9 to 1.6 fold)in the C100 group compared to the C0 group(P<0.05).Based on the quadratic regression analysis between FBW,WGR,or SGR and dietary Chlorella meal level,largemouth bass had the best growth when replacing 31.7%to 32.6%of fish meal with 15.03%to 15.43%dietary Chlorella meal.The present results indicated that dietary supplementation with Chlorella meal(11.85%to 47.45%)significantly enhanced the pigmentation;however,total replacement of fish meal(40%)with Chlorella meal(47.45%)caused growth retardation,apoptosis,and liver damage in largemouth bass.
基金the National Key R&D Program of China(2019YFD0900200 and 2018YFD0900400)the National Natural Science Foundation of China(32172981 and 31902382)+1 种基金the Agricultural Science and Technology Innovation Programof CAAS in China(CAAS-ASTIP-2017-FRI-08)China Postdoctoral Science Foundation(2021M703544).
文摘Clostridium autoethanogenum protein(CAP)is a new single-cell protein source originating from inactivated bacteria.An in vitro digestion experiment and an 8-wk growth experiment were conducted to evaluate the molecular weight distribution of the CAP hydrolysate,and the effects of dietary CAP levels on the growth performance,plasma parameters,hepatic and intestinal health,and the diversity of gutadherent microbiota of largemouth bass(Micropterus salmoides).The fish(initial body weight of 47.99±0.01 g)were fed diets where CAP gradually replaced 0%(CAP0),12.5%(CAP12.5),25%(CAP25),37.5%(CAP37.5)and 50%(CAP50)of low-temperature steam dried anchovy fish meal(LTFM)in the diet.Results showed that the content of peptides below 1,000 Da in the CAP hydrolysate(0.56 mg/mL)was higher than that of the LTFM hydrolysate(0.48 mg/mL).Dietary CAP inclusion had no negative effect on growth performance,while whole-body lipid content significantly reduced in the CAP25 and CAP50 groups(P<0.05).The plasma alanine aminotransferase activities and triglyceride concentrations in the CAP inclusion groups were significantly lower than those in the CAP0 group(P<0.05).The plasma aspartate aminotransferase activity was significantly reduced in the CAP37.5 group(P<0.05).The richness and diversity of the gut-adhesive microbiota and the proportion of Clostridium sensu stricto 12 in the CAP50 group were significantly higher than those in the CAP0 group(P<0.05).Dietary CAP inclusion inhibited inflammatory responses by down-regulating the mRNA levels of interleukin 1b(IL1b),IL10 and transforming growth factor b1(P<0.05)in the liver.The mRNA levels of acetyl-CoA carboxylase 1 were significantly down-regulated in the CAP12.5,CAP25 and CAP37.5 groups(P<0.05),while that of fatty acid synthase was significantly down-regulated in the CAP50 group(P<0.05).These results demonstrate that dietary CAP inclusion could improve the hepatic and intestinal health of largemouth bass,and can be helpful to further develop CAP as a functional feed ingredient.
基金supported by the National Key R&D Program of China(2022YFD1300600)Beijing Innovation Consortium of Agriculture Research System(BAIC07-2022).
文摘Cottonseed protein concentrate is a sustainable fishmeal alternative in aquafeed.A 10-week experiment was conducted to investigate the effects of a cottonseed protein concentrate-based diet with and without multi-strain yeast fractions(MsYF)on growth,bile acid metabolism,and health in largemouth bass.Four hundred fish(54.0±0.0 g)were casually distributed into 16 tanks(4 replicates/diet).Fish were fed with 4 iso-nitrogen and iso-energetic diets 3 times daily,including a fishmeal diet(FM),a soy protein concentrate-based diet(SPC;replacing 81%fishmeal protein),a cottonseed protein concentrate-based diet(CPC;replacing 81%fishmeal protein),and a CPC diet supplemented with 800 mg/kg MsYF(CPCY).Results showed that the survival of SPC was the lowest,i.e.,48%,with no apparent diet effect among other treatments;we omitted the SPC in additional analyses.Fish fed cottonseed protein concentrate-based diets showed lower growth than FM(P<0.05).Fish fed CPC showed the highest nuclear dense hepatic phenotypes ratio(50%),followed by CPCY(33%)and FM(17%).Further,dietary CPC increased hepatic total cholesterol and triglyceride levels with concurrently increased cholesterol syn-thesis but decreased triglyceride synthesis-associated transcription levels(P<0.05).Furthermore,di-etary CPC increased bile acid synthesis but decreased bile acid transport-associated transcription levels(P<0.05),and then induced an increment of plasma cholic acid and hepatic chenodeoxycholic acid content and the decrement of genus Romboustia(P<0.05).Regarding the effect of MsYF,fish fed CPCY reduced hepatic lipid accumulation and total plasma bile acid content(P<0.05)compared to CPC,suggesting an improvement in liver health.Also,dietary MsYF could reverse the microbiota community structure showing a similar gut microbial composition to FM.In conclusion,81%of fishmeal protein replaced by cottonseed protein concentrate suppressed growth and liver health,while dietary MsYF might mitigate the negative impact of a high cottonseed protein concentrate level diet on liver functions via gut microbiota regulation.
基金supported by Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Team(2023KJ150)Special Project on Key Fields of Guangdong Universities(Rural Revitalization)(2020ZDZX1034).
文摘This study was conducted to evaluate the influence of dietary lysophospholipids combined with 1%dietary fish oil reduction on the growth performance and hepatic lipid metabolism of largemouth bass(Micropterus salmoides).Five isonitrogenous feeds were prepared with lysophospholipids at 0%(fish oil group,FO),0.05%(L-0.05),0.1%(L-0.1),0.15%(L-0.15)and 0.2%(L-0.2),respectively.The dietary lipid was 11%in the FO diet and 10%in the other diets.Largemouth bass were fed for 68 d(initial body weight=6.04±0.01 g)with 4 replicates per group and 30 fish per replicate.The results showed that the fish fed diet containing 0.1%lysophospholipids had higher digestive enzyme activity and obtained better growth performance compared to the fish fed FO diet(P<0.05).The feed conversion rate in the L-0.1 group was significantly lower than that in the other groups.Serum total protein and triglyceride contents in L-0.1 group were significantly higher than those in other groups(P<0.05)and the contents of total cholesterol and low-density lipoprotein cholesterol in L-0.1 group were significantly lower than those in FO group(P<0.05).The activity and genes expression of hepatic glucolipid metabolizing enzymes in L-0.15 group were significantly increased compared to those in FO group(P<0.05).Reducing 1%fish oil along with 0.1%lysophospholipids added to the feed could improve the digestion and absorption of nutrients,enhance the activity of liver glycolipid metabolizing enzymes,and thus effectively promote the growth of largemouth bass.
