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
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
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
Nano-additives can improve the absorption and utilization of feed nutrients.In this study,we reported the effects of supplementary nano iron(0,30,60,120,240 and 480 mg/kg)on intestinal tract function of largemouth bas...Nano-additives can improve the absorption and utilization of feed nutrients.In this study,we reported the effects of supplementary nano iron(0,30,60,120,240 and 480 mg/kg)on intestinal tract function of largemouth bass juveniles.Firstly,60 mg/kg of supplementary nano iron improved specific growth rates of largemouth bass,and significantly increased the height and width of intestinal villi and intestinal absorption area.Secondly,supplementation of low concentrations of nano iron through intraperitoneal injection significantly increased the activity of intestinal antioxidant enzymes catalase and total superoxide dismutase(CAT and T-SOD),enhanced the expression of antioxidant-related genes(sod1,nrf-2)and proteins(CAT;P<0.05),and decreased malondialdehyde(MDA)content,resulting in higher survival rates of Nocardia seriolae.Supplementation of 480 mg/kg compromised the immune and antioxidant capacity of juvenile largemouth bass,as evident by the increased expression of inflammatory and apoptotic genes,significant reduction in the expression of intestinal tight junction genes(zo-1,claudin1,claudin7;P<0.05),impairment of intestinal physical barriers,and exacerbation of oxidative stress levels.Through quadratic regression analysis,the optimal dietary supplementation level of nano iron for juvenile largemouth bass was determined to be approximately 80 mg/kg.In conclusion,moderate supplementation of nano iron appears to enhance the intestinal physical barrier,antioxidant capacity,and immune function of juvenile largemouth bass.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
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
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 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.
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 Natural Science Foundation of Sichuan Province,China(NO:2024NSFSC2069)also supported by the Freshwater Fish Innovation of Sichuan Province,China(NO.SCCXTD-2025-15).
文摘Nano-additives can improve the absorption and utilization of feed nutrients.In this study,we reported the effects of supplementary nano iron(0,30,60,120,240 and 480 mg/kg)on intestinal tract function of largemouth bass juveniles.Firstly,60 mg/kg of supplementary nano iron improved specific growth rates of largemouth bass,and significantly increased the height and width of intestinal villi and intestinal absorption area.Secondly,supplementation of low concentrations of nano iron through intraperitoneal injection significantly increased the activity of intestinal antioxidant enzymes catalase and total superoxide dismutase(CAT and T-SOD),enhanced the expression of antioxidant-related genes(sod1,nrf-2)and proteins(CAT;P<0.05),and decreased malondialdehyde(MDA)content,resulting in higher survival rates of Nocardia seriolae.Supplementation of 480 mg/kg compromised the immune and antioxidant capacity of juvenile largemouth bass,as evident by the increased expression of inflammatory and apoptotic genes,significant reduction in the expression of intestinal tight junction genes(zo-1,claudin1,claudin7;P<0.05),impairment of intestinal physical barriers,and exacerbation of oxidative stress levels.Through quadratic regression analysis,the optimal dietary supplementation level of nano iron for juvenile largemouth bass was determined to be approximately 80 mg/kg.In conclusion,moderate supplementation of nano iron appears to enhance the intestinal physical barrier,antioxidant capacity,and immune function of juvenile largemouth bass.
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.
