Background The carnivorous fish,largemouth bass(Micropterus salmoides),has difficulty metabolizing dietary carbohydrates,frequently resulting in issues with energy metabolism and fatty liver disease.Nevertheless,the m...Background The carnivorous fish,largemouth bass(Micropterus salmoides),has difficulty metabolizing dietary carbohydrates,frequently resulting in issues with energy metabolism and fatty liver disease.Nevertheless,the molecular mechanisms involved are still not fully understood.Results The results of high-carbohydrate(HC)diets and high-glucose(HG)treatments in largemouth bass hepatocytes showed that high-glucose causes liver damage and glycolipid accumulation.High-glucose promoted the lipogenesis process by activating AMPK/ACC/SREBP-1 pathway and reduced bile acid synthesis by downregulating cholesterol 7-hydroxylase(cyp7a1)and sterol 12-hydroxylase(cyp8b1).Concurrently,HG treatments also caused mitochondrial fission and damage by increasing the expression of dynamin-related protein 1(Drp1),leading to impaired mitochondria accumulation and mitochondria-dependent apoptosis via the p38 MAPK/Bcl-2/Casp3 pathway.Additionally,HG treatments decreased Sirt1 expression and relocated it from the nucleus to the cytoplasm,where it interacts with autophagosomes and lysosomes,inhibiting Pink1/Parkin-mediated mitophagy.This also led to the cytoplasmic translocation of Pink1 and its co-localization with Sirt1,indicating that Sirt1 regulates high glucose-induced metabolic stress by inhibiting the Pink1/Parkin mitophagy pathway.Conclusion In summary,HG treatment induces mitochondrial damage and glycolipid accumulation in largemouth bass through mechanisms involving AMPK/SREBP1/ACC1-mediated lipogenesis,bile acid metabolism,Sirt-mediated mitophagy,and p38 MAPK/Bcl-2/Casp3-activated apoptosis.展开更多
Background To more effectively address the scarcity resources and elevated costs associated with fishmeal(FM),the utilization of cottonseed protein concentrate(CPC)as an alternative in aquaculture feeds has become inc...Background To more effectively address the scarcity resources and elevated costs associated with fishmeal(FM),the utilization of cottonseed protein concentrate(CPC)as an alternative in aquaculture feeds has become increasingly prevalent.However,high levels of CPC substitution for FM have been reported to suppress the growth of fish and impair intestinal health.Hydrolysable tannin(HT)has been reported to exhibit biological activities such as antiinflammatory and antioxidant activities,but whether the HT can generate positive biological effects on the intestinal health of largemouth bass(Micropterus salmoides)remains unknown.Largemouth bass(initial weight:6.03±0.01 g)were subjected to an 8-week feeding trial with three different diets:a basic diet(named as the NC),a high CPC diet(in which CPC replaced 75%of the FM protein in the NC diet,named as the HC),and an additive diet(1.25 g/kg of the HT was added to the HC diet,named as the HCH)to explore the potential benefits of HT on intestinal health.Results The HC treatment significantly reduced the weight gain rate of fish,increased the feed conversion ratio,and induced intestinal inflammation.However,the HCH treatment could alleviate the adverse impacts of the HC diet,as evidenced by the promotion of growth and feed utilization,increased activity of digestive enzymes and antioxidant capacities,downregulated expression of pro-inflammatory factors,and maintenance of the integrity of intestinal barrier.Metabolomic analysis revealed that HCH treatment could reduce the pro-inflammatory active substances produced by arachidonic acid metabolism,including prostaglandin F2α(PGF2α)and leukotriene B4(LTB4).Transcriptomic results indicated that dietary HT might alleviate intestinal inflammation by suppressing the activation of the NF-κB signaling pathway.Furthermore,correlation analysis demonstrated that the metabolites PGF2αand LTB4,derived from arachidonic acid,exhibited a significant positive correlation with the expression of genes associated with proinflammatory responses within the NF-κB signaling pathway.Conclusions The study indicates that the HT mitigates the growth retardation and intestinal inflammation resulting from the HC diet on largemouth bass.展开更多
Myostatin or GDF-8, a member of the transforming growth factor-β （TGF-β） superfamily, has been demonstrated to be a negative regulator of skeletal muscle mass in mammals. In the present study, we obtained a 5.64 k...Myostatin or GDF-8, a member of the transforming growth factor-β （TGF-β） superfamily, has been demonstrated to be a negative regulator of skeletal muscle mass in mammals. In the present study, we obtained a 5.64 kb sequence of myostatin encoding gene and its promoter from largemouth bass （Micropterus salmoides）. The myostatin encoding gene consisted of three exons （488bp, 371 bp and 1779bp, respectively） and two introns （390bp and 855 bp, respectively）. The intron-exon boundaries were conservative in comparison with those of mammalian myostatin encoding genes, whereas the size of introns was smaller than that of mammals. Sequence analysis of 1.569 kb of the largemouth bass myostatin gene promoter region revealed that it contained two TATA boxes, one CAAT box and nine putative E-boxes. Putative muscle growth response elements for myocyte enhancer factor 2 （MEF2）, serum response factor （SRF）, activator protein 1 （AP1）, etc., and muscle-specific Mt binding site （MTBF） were also detected. Some of the transcription factor binding sites were conserved among five teleost species. This infunnation will be useful for studying the tran- scriptional regulation of myostatin in fish.展开更多
Largemouth bass(Micropterus salmoides) is an economically important fish species in North America, Europe, and China. Various genetic improvement programs and domestication processes have modified its genome sequence ...Largemouth bass(Micropterus salmoides) is an economically important fish species in North America, Europe, and China. Various genetic improvement programs and domestication processes have modified its genome sequence through selective pressure, leaving nucleotide signals that can be detected at the genomic level. In this study,we sequenced 149 largemouth bass fish, including protospecies(imported from the US) and improved breeds(four domestic breeding populations from China). We detected genomic regions harboring certain genes associated with improved traits, which may be useful molecular markers for practical domestication, breeding, and selection. Subsequent analyses of genetic diversity and population structure revealed that the improved breeds have undergone more rigorous genetic changes. Through selective signal analysis, we identified hundreds of putative selective sweep regions in each largemouth bass line. Interestingly, we predicted 103 putative candidate genes potentially subjected to selection,including several associated with growth(psst1 and grb10), early development(klf9, sp4, and sp8), and immune traits(pkn2, sept2, bcl6, and ripk2). These candidate genes represent potential genomic landmarks that could be used to improve important traits of biological and commercial interest. In summary, this study provides a genome-wide map of genetic variations and selection footprints in largemouth bass, which may benefit genetic studies and accelerate genetic improvement of this economically important fish.展开更多
Pituitary adenylate cyclase activating polypeptide （PACAP） has a wide range of biological functions. We cloned the full-length cDNAs encoding PACAP and PACAP-related peptide （PRP） from the brain of largemouth bass...Pituitary adenylate cyclase activating polypeptide （PACAP） has a wide range of biological functions. We cloned the full-length cDNAs encoding PACAP and PACAP-related peptide （PRP） from the brain of largemouth bass （Micropterus salmoides） and used real-time quantitative PCR to detect PRP- PACAP mRNA expression. The PRP-PACAP cDNA has two variants expressed via alternative splicing： a long form, which encodes both PRP and PACAP, and a short form, which encodes only PACAR Sequence analysis results are consistent with a higher conservation of PACAP than PRP peptide sequences. The expression of PACAP-Iong and PACAP-short transcripts was highest in the forebrain, followed by the medulla, midbrain, pituitary, stomach, cerebellum, intestine, and kidney; however, these transcripts were either absent or were weakly expressed in the muscle, spleen, gill, heart, fatty tissue, and liver. The level of PACAP-short transcript expression was significantly higher than expression of the long transcript in the forebrain, cerebella, pituitary and intestine, but lower than that of the long transcript in the stomach. PA CAP- long and PACAP-short transcripts were first detected at the blastula stage of embryogenesis, and the level of expression increased markedly between the muscular contraction stage and 3 d post hatch （dph）. The expression of PACAP-long and PACAP-short transcripts decreased significantly in the brain following 4 d fasting compared with the control diet group. The down-regulation effect was enhanced as fasting continued. Conversely, expression levels increased significantly after 3 d of re-feeding. Our results suggest that PRP- PA CAP acts as an important factor in appetite regulation in largemouth bass.展开更多
Background Adequate level of carbohydrates in aquafeeds help to conserve protein and reduce cost. However, studies have indicated that high-carbohydrate(HC) diet disrupt the homeostasis of the gut–liver axis in large...Background Adequate level of carbohydrates in aquafeeds help to conserve protein and reduce cost. However, studies have indicated that high-carbohydrate(HC) diet disrupt the homeostasis of the gut–liver axis in largemouth bass, resulting in decreased intestinal acetate and butyrate level.Method Herein, we had concepted a set of feeding experiment to assess the effects of dietary sodium acetate(SA) and sodium butyrate(SB) on liver health and the intestinal microbiota in largemouth bass fed an HC diet. The experimental design comprised 5 isonitrogenous and isolipidic diets, including LC(9% starch), HC(18% starch), HCSA(18% starch;2 g/kg SA), HCSB(18% starch;2 g/kg SB), and HCSASB(18% starch;1 g/kg SA + 1 g/kg SB). Juvenile largemouth bass with an initial body weight of 7.00 ± 0.20 g were fed on these diets for 56 d.Results We found that dietary SA and SB reduced hepatic triglyceride accumulation by activating autophagy(ATG101, LC3B and TFEB), promoting lipolysis(CPT1α, HSL and AMPKα), and inhibiting adipogenesis(FAS, ACCA, SCD1 and PPARγ). In addition, SA and SB decreased oxidative stress in the liver(CAT, GPX1α and SOD1) by activating the Keap1-Nrf2 pathway. Meanwhile, SA and SB alleviated HC-induced inflammation by downregulating the expression of pro-inflammatory factors(IL-1β, COX2 and Hepcidin1) through the NF-κB pathway. Importantly, SA and SB increased the abundance of bacteria that produced acetic acid and butyrate(Clostridium_sensu_stricto_1). Combined with the KEGG analysis, the results showed that SA and SB enriched carbohydrate metabolism and amino acid metabolism pathways, thereby improving the utilization of carbohydrates. Pearson correlation analysis indicated that growth performance was closely related to hepatic lipid deposition, autophagy, antioxidant capacity, inflammation, and intestinal microbial composition.Conclusions In conclusion, dietary SA and SB can reduce hepatic lipid deposition;and alleviate oxidative stress and inflammation in largemouth bass fed on HC diet. These beneficial effects may be due to the altered composition of the gut microbiota caused by SA and SB. The improvement effects of SB were stronger than those associated with SA.展开更多
High density lipoprotein binding protein （HBP） plays an important role in lipid metabolism of animals. Lipids are indispensable energy materials for fi- shes, especially for carnivorous fishes with low utilization e...High density lipoprotein binding protein （HBP） plays an important role in lipid metabolism of animals. Lipids are indispensable energy materials for fi- shes, especially for carnivorous fishes with low utilization efficiency of carbohydrates. The single nucleotide polymorphism （SNP） of HBP gene may affect the fat metabolism, thereby exerting an effect on the growth traits of largemouth bass （Micropterus salmoides）. Investigating the correlations between SNP and growth traits can provide candidate markers for molecular marker-assisted selection. In this study, partial genomic fraganents of HBP gene （ GenBank accession number： KF652241 ） were amplified based on the sequences of an available contig in the EST-SNP database of largemouth bass. Three SNP mutation loci were identified in the 3＇ non-ceding region of HBP gene by direct sequencing, including H1 （G ＋ 2782T）, 142 （T ＋ 2817C） and H3 （G ＋ 2857A）. Three SNP loci of 165 randomly selected largemouth bass individuals were detected and genotyped by SnaPshot assay. Genetic structure was analyzed by POPGENE32 software. By using spssl7.0 software, a general linear model （GLM） was established for correlation analysis between different genotypes at SNP loci of HBP gene and various growth traits. The results showed that three SNP loci were in Hardy-Weinberg equilibrium state. To be specific, loci H1 and H2 formed two haplotypes （ A and B）, and three geno- types （AA, AB, and BB） were observed; loci H1, H2 and H3 formed six diplotypes （DI, I）2, D3, D4, D5 and D6）. According to the correlations between dif- ferent genotypes and various growth traits, the body weight and total length of largemouth bass individuals with genotype BB were significantly higher than those of individuals with genotype AB （ P 〈 0.05 ） ; the body weight and total length of largemouth bass individuals with diplotype D6 were significantly higher than those of individuals with diplotype D4 （P 〈0.05）. In this study, SNP markers correlated with growth traits were obtained in the 3＇ non-coding region ofHBP gene in large-mouth bass, which could be used as candidate genetic markers for subsequent molecular marker-assisted selection breeding of largemouth bass.展开更多
Global warming threatens freshwater ecosystems and compromises fish survival.To elucidate the role of miRNAs in the livers of heat stressed largemouth bass,juvenile fish was subject to heat stress under 37°C.Both...Global warming threatens freshwater ecosystems and compromises fish survival.To elucidate the role of miRNAs in the livers of heat stressed largemouth bass,juvenile fish was subject to heat stress under 37°C.Both mRNA-seq and miRNA-seq were conducted on the liver tissues under control and heat stress conditions.Differential gene expression analysis and enrichment analysis were performed on mRNA and miRNA expression profiles.A total of 406 differentially expressed genes(DEGs)were discovered,of which 212 were up-regulated and 194 were down-regulated.Most of the DEGs were significantly implicated in the regulation of“protein processing in endoplasmic reticulum”,“proteasome”,“steroid biosynthesis”,and“ornithine decarboxylase inhibitor activity”pathways.In addition,47 differentially expressed miRNAs(DEMs)were identified in largemouth bass livers under heat stress,including 21 up-regulated and 25 down-regulated miRNAs.A negatively regulated miRNA-mRNA network including 12 miRNAs and 19 mRNAs was constructed with DEMs involved in“protein degradation”,“calcium ion regulation”,“cell apoptosis”,and“lipid metabolism”.Moreover,this study indicated novel-miR-144 activated the IRE1 signaling pathway by targeting txndc5 to induce liver apoptosis in largemouth bass under heat stress.This study revealed the involvement of miRNA regulation in largemouth bass in response to heat stress.展开更多
Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (<span style="white-space:nowrap;"><i></span>Mic...Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (<span style="white-space:nowrap;"><i></span>Micropterus salmoides<span style="white-space:nowrap;"></i></span>) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow (<span style="white-space:nowrap;"><i></span>Pimephales promelas<span style="white-space:nowrap;"></i></span>) forage during 2015. At harvest, age-0 bass yield was 4.5 times greater and average fish length was 38 mm longer, in the pond that received fathead minnow. In 2016, a second study evaluated the timing of minnow supplementation that included earlier stockings of small fathead minnow (<30 mm) compared to delayed supplementation with larger (>30 mm) minnows. With earlier supplementation, bass yield was 2.3 times greater and fish averaged 14 mm longer at harvest. Bass survival was approximately 38% higher during 2015 when supplementation occurred and 25% higher during 2016 when minnow supplementation began earlier. Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production.展开更多
An understanding of the relative importance of natural factors and management practices affecting largemouth bass (Micropterus salmoides) abundance is key for enhanced angling. Standardized fish surveys, management pr...An understanding of the relative importance of natural factors and management practices affecting largemouth bass (Micropterus salmoides) abundance is key for enhanced angling. Standardized fish surveys, management practices, and environmental data were available from 42 man-made, inland lakes between 1960 and 1991. Management practices tested were largemouth bass stocking, lake rehabilitation, water level manipulation, aquatic vegetation controls, small fish removal, and changes in length limits of harvestable fish. Environmental factors not controlled by management were spring water influx, growing and cooling degree days, and snow depth. Lake rehabilitation (complete drainage and reflooding), changes in length limits, and aquatic vegetation controls were the only significant factors affecting largemouth bass abundance. The largest effects were due to lake rehabilitation, which increased next-year young largemouth bass numbers by 566% on average, and more restrictive limits on harvestable size, with an increase of up to 440% in adult numbers.展开更多
Excessive largemouth bass ( Micropterus salmoides ) recruitment in small impoundments leads to density-dependent growth depression, causing populations to have length distributions skewed towards smaller fish. To addr...Excessive largemouth bass ( Micropterus salmoides ) recruitment in small impoundments leads to density-dependent growth depression, causing populations to have length distributions skewed towards smaller fish. To address this issue, we conducted three trials that evaluated stocking all female largemouth bass (F-LMB) in two small Alabama ponds (0.5 and 2.0 ha) where the drainage basin was isolated. Age-1 fish were individually identified for sex using a micro pipette inserted in the urogenital pore, tagged, and stocked at 38-40 F-LMB/ha into ponds that contained pre-established sunfish ( Lepomis spp.) populations. Female largemouth bass were collected with electrofishing, angling, and rotenone over a 2.5- to 5-year period among the three trials. Sex was correctly identified for 179 of the 180 F-LMB stocked. One male was detected in the first trial which resulted in successful largemouth bass reproduction and this trial was terminated after two years. Growth was rapid the first 2 years after stocking as 3-year-old fish reached an average of 429 to 459 mm and 1.37 to 1.66 kg in all 3 trials. However, 2 years after stocking, growth was nil in the second trial even though relative weights of F-LMB were generally greater than 100. In this second trial, removal of about 30% of the F-LMB inhabiting the pond and stocking small Nile tilapia Oreochromis niloticus (25 - 75 mm) resulted in average weights increasing from 1.30 to 2.34 kg in 1 year. Growth of F-LMB continued in the third trail, and average size approached 500 mm and 2.2 kg three years after stocking. Annual survival rates of F-LMB were high and ranged from 0.78 to 0.93 among the 3 trials. Stocking F-LMB offers an attractive alternative in ponds to create a low density largemouth bass population that displays fast growth and high survival when catch-and-release fishing is primarily practiced.展开更多
Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable am...Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable amino acids and different carbohydrate to lipid ratios influence those systems. Therefore, the present study aimed to evaluate whether arginine （Arg） intake and carbohydrate to lipid ratios would affect expression of GH, IGF-Ⅰ and INS in largemouth bass.展开更多
To trigger compensatory growth(CG)with novel protein sources in juvenile largemouth bass(Micropterus salmoides)(initial weight:4.73±0.04 g),Chlorella(Chlorella vulgaris,ChM),cottonseed protein concentrate(CSM),Cl...To trigger compensatory growth(CG)with novel protein sources in juvenile largemouth bass(Micropterus salmoides)(initial weight:4.73±0.04 g),Chlorella(Chlorella vulgaris,ChM),cottonseed protein concentrate(CSM),Clostridium autoethanogenum(CAP)and yellow mealworm(Tenebrio molitor,TM)were applied to completely substitute fishmeal in the diet during a four-week dietary restriction phase(the first phase).After being refed with fishmeal(FM)diet for the next four weeks(the second phase),the growth performance,proximate composition,biochemical parameters and liver condition of treatment groups(denoted as ChM,CSM,CAP,TM group,respectively)were assessed and compared with the control group(denoted as FM group),which was consistently fed with fishmeal diets.All groups exhibited different responses during restriction and refeeding phases.The CSM,CAP,and TM groups experienced initial growth reduction followed by accelerated growth,whereas the ChM group maintained steady growth.Compensation coefficient results indicated that only ChM and CSM groups achieved compensatory growth,although there was still a gap in final weight compared with FM group.Regarding the liver condition,histopathological analysis and biochemical parameters revealed a gradual increase in lipid accumulation in the FM group during the second phase,accompanied by slowing growth.The CSM,CAP,TM groups showed varying degrees of liver injury,with the CAP group exhibiting elevated serum transaminase(ALT and AST)activity and a dramatically higher content of malondialdehyde(MDA)in liver.Conversely,the ChM group possessed healthier livers,characterized by active antioxidative capacity and low content of total triglyceride(TG).Meanwhile,abnormal lipid deposition and different amino acid content were observed throughout the FM group,potentially affecting the fish quality compared with the ChM group.Overall,the results demonstrated the feasibility and potential of triggering compensatory growth by completely replacing fishmeal with Chlorella,which exhibited the showed superior performance among novel protein sources.展开更多
The present study investigated the potential effects of an umami taste stimulator(UTS)on largemouth bass(Micropterus salmoides)fed a high plant protein diet.Two isonitrogenous and isolipidic diets were formulated with...The present study investigated the potential effects of an umami taste stimulator(UTS)on largemouth bass(Micropterus salmoides)fed a high plant protein diet.Two isonitrogenous and isolipidic diets were formulated with 40%fishmeal(positive control,PC)and 25%fishmeal(negative control,NC),respectively.The other three diets were supplemented with 0.10%,0.15%and 0.20%of the UTS based on NC group.Five groups of fish(mean initial weight 29.82±0.04 g)were fed twice daily for 64 days.The results indicated that feed intake,growth performance,and taste receptor and enteroendocrine-related genes expression(pyya,t1r1 and ghrl)in NC group were significantly reduced compared with PC group,which were improved with dietary supplementation of the UTS(at 0.15%and 0.20%).In addition,muscle thickness of midgut and hindgut,villus length of hindgut in the NC group were reduced compared to the PC group,but they improved with dietary UTS supplementation.Also,antioxidant capacity,and expression of genes involved in peptide and amino acid transport and target of rapamycin(TOR)pathway were reduced in the NC group compared to the PC group.However,the inclusion of UTS improved the total antioxidant capacity,superoxide dismutase and catalase compared with the NC group.Peptide and amino acid transporters(lat1,lat2,snat2 and pept2)and TOR pathway(tor,akt1,4ebp1 and s6)related genes’expression were also ameliorated by UTS addition compared to the NC group.In summary,UTS supplementation could improve the appetite,growth performance,and health status of largemouth bass,and the recommended additional amount of UTS was 0.15%-0.20%.展开更多
Frequent occurrences of extreme weather events,particularly severe temperature fluctuations,have significantly impaired the growth and health of fish and resulted in detrimental impacts on aquaculture production.Despi...Frequent occurrences of extreme weather events,particularly severe temperature fluctuations,have significantly impaired the growth and health of fish and resulted in detrimental impacts on aquaculture production.Despite recognition of the crucial role that temperature plays in aquaculture,there is currently inadequate research to assess the consequences of extreme temperature fluctuations on fish health.Hence,we set up acute warming(AW)and cooling groups(AC)by increasing or decreasing water temperature by 8℃ and then gradually restoring the initial temperature(22℃),to investigate the adaptive regulation of energy metabolism,immune function,and gut microbiota in largemouth bass(Micropterus salmoides).The fish antioxidant system responded to assist their environmental adaptation:both groups showed activation of serum superoxide dismutase(SOD)and catalase(CAT)secretion,and a significant increase in serum total antioxidant capacity(T-AOC)(P<0.05).Distinct metabolic strategies were employed to cope with sudden environmental perturbations:upon experi-encing a temperature decrease(AC1),largemouth bass exhibited a significant increase in serum triglyceride(TG)and cholesterol(CHOL)levels(P<0.05),coupled with a reduction in blood glucose levels(P<0.05).However,a considerable reduction in serum TG and CHOL levels was observed after acute warming stage(AW1)(P<0.05).Following the recovery of temperature,both groups demonstrated a tendency towards normal energy metabolism(CON).Compared to the AW group,the immune function of largemouth bass in the AC group was dramatically affected:alkaline phosphatase(AKP),aspartate transaminase(AST),and alanine transaminase(ALT)increased significantly,while lysozyme(LZM)decreased significantly when the temperature dropped sharply(P<0.05).After the temperature fluctuations,there were apparent changes in the gut morphology and microbiota of largemouth bass.Microbial functional analysis using the KEGG database revealed apparent al-terations in microbial biological functions,especially during the cooling fluctuation(AC).The results indicated that dramatic weather changes,particularly extreme cold,may be detrimental to the health and welfare of largemouth bass.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
This study investigated the effects of replacing fishmeal with Clostridium autoethanogenum protein(CAP)on growth,feed utilization and intestinal histology of largemouth bass(Micropterus salmoides).The control diet con...This study investigated the effects of replacing fishmeal with Clostridium autoethanogenum protein(CAP)on growth,feed utilization and intestinal histology of largemouth bass(Micropterus salmoides).The control diet contained 350 g/kg fishmeal,and then dietary fishmeal was decreased to 300 g/kg,250 g/kg,200 g/kg,150 g/kg and 100 g/kg by CAP inclusion,respectively(FM-30,FM-25,FM-20,FM-15,FM-10).The largemouth bass(110.0±1.0 g)were fed one of the six diets for 8 weeks.The groups of FM-30,FM-25 and FM-20 showed the similar weight gain(WG)and feed conversion ratio(FCR)to the control(P>0.05),while the WG of FM-10 group was decreased by 15.9%,and FCR increased by 0.12 when compared to the control(P<0.05).FM-15 and FM-10 groups had lower protein retention,lower villus height in intestine and higher serum malondialdehyde content than the control(P<0.05).The protease activity in FM-20,FM-15 and FM-10 groups was lower than that in the control(P<0.05),but no difference was observed in crude protein digestibility among groups(P>0.05).In conclusion,CAP could replace 150 g/kg fishmeal in diet(350 g/kg fishmeal)without adverse effects on growth,feed utilization and intestinal histology of largemouth bass.展开更多
Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry.This study aimed to investigate the effects of bile acids(BAs)on gut barriers in Micropterus salmoides.A germ-fre...Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry.This study aimed to investigate the effects of bile acids(BAs)on gut barriers in Micropterus salmoides.A germ-free(GF)zebrafish model was employed to elucidate the effects of the direct stimulation of BAs and the indirect regulations mediated by the gut microbiota on gut barrier functions.Four diets were formulated with BAs supplemented at 0,150,300 and 450 mg/kg,and these 4 diets were defined as control,BA150,BA300 and BA450,respectively.After 5 weeks of feeding experiment,the survival rate of fish fed with BA300 diet was increased(P<0.05).Histological analysis revealed an improvement of gut structural integrity in the BA150 and BA300 groups.Compared with the control group,the expression of genes related to chemical barrier(mucin,lysozyme and complement 1)and physical barrier(occludin and claudin-4)was increased in the BA150 and BA300 groups(P<0.05),and the expression of genes related to immunological barrier(interleukin[IL]-6,tumor growth factorβ,IL-10,macrophage galactosetype lectin and immunoglobulin M[Ig M])was significantly increased in the BA300 group(P<0.05),but the expression of genes related to chemical barrier(hepcidin)and immunological barrier(IL-1β,tumor necrosis factor-a,IL-6 and arginase)was significantly decreased in the BA450 group(P<0.05).Gut microbiota composition analysis revealed that the abundance of Firmicutes was augmented prominently in the BA150 and BA300 groups(P<0.05),while that of Actinobacteriota and Proteobacteria showed a downward trend in the BA150 and BA300 groups(P>0.05).The results of the gut microbiota transferring experiment demonstrated an upregulation of gut barrier-related genes,including immunoglobulin Z/T(Ig Z/T),IL-6,IL-1βand IL-10,by the gut microbiota transferred from the BA300 group compared with the control(P<0.05).Feeding the BA300 diet directly to GF zebrafish resulted in enhanced expression of Ig M,Ig Z/T,lysozyme,occludin-2,IL-6 and IL-10(P<0.05).In conclusion,BAs can improve the gut barriers of fish through both direct and indirect effects mediated by the gut microbiota.展开更多
An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass.A total of 600 healthy fish(12.96±0.07 g)were fed diets containing varying levels of vitamin K3 at 0.78(K0),5.80...An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass.A total of 600 healthy fish(12.96±0.07 g)were fed diets containing varying levels of vitamin K3 at 0.78(K0),5.80(K5),10.82(K10),15.84(K15),and 20.85(K20)mg/kg with four replicates per level.Results showed that dietary vitamin K3 enhanced growth,with weight gain rate and specific growth rate in K15 trials significantly higher than K0 trials(P<0.05).No significant difference was observed in the content of crude protein,crude lipid,moisture,ash,and phosphorus in muscle tissue(P>0.05).However,the supplementation of vitamin K3 significantly contributed to calcium accumulation in muscle tissues and vertebrae(P<0.05)and increased red blood cell counts(P<0.05).The blood coagulation time decreased significantly with increasing dietary vitamin K3 from 0.78 to 10.82 mg/kg(P<0.05)before stabilizing(P>0.05).The antioxidant capacity was improved with the addition of vitamin K3,which was inconsistent with the changes in malondialdehyde and MK-4(a form of menaquinone)within liver and serum,suggesting that the toxicity of excessive artificial vitamin K3 may account for this difference.Using regression analysis,the appropriate dietary vitamin K3 levels within a largemouth bass diet was determined to be in the range of 9.93-15.22 mg/kg,which will provide a reference for the preparation of vitamin premix and artificial diet for largemouth bass.展开更多
The present study was conducted to estimate the optimum requirement of phosphorus in practical diets for largemouth bass(Micropterus salmoides).Six iso-energetic and iso-nitrogenous diets were formulated with the supp...The present study was conducted to estimate the optimum requirement of phosphorus in practical diets for largemouth bass(Micropterus salmoides).Six iso-energetic and iso-nitrogenous diets were formulated with the supplementation of monocalcium phosphate(MCP)of 0,5,10,15,20 and 25 g/kg in basal diet containing 350 g/kg fish meal,respectively.The digestible phosphorus of the six diets was measured as 5.7,6.7,7.8,8.7,9.3 and 10.0 g/kg,respectively.Each diet was randomly fed to triplicate groups of 25 juvenile fish(initial body weight,16.0±0.2 g)for 60 days.The results showed that weight gain increased,and feed conversion ratio decreased with the increase of dietary phosphorus.When dietary MCP exceeded 15 g/kg(digestible phosphorus of 8.7 g/kg),the WG and FCR were maintained at the similar values.The crude ash,phosphorus and calcium contents in whole body,apparent digestibility of phosphorus and protein retention also increased with the increasing phosphorus level in diets.Vertebrae phosphorus and calcium levels and plasma phosphorus showed no further increase when dietary MCP reached 20,20 and 10 g/kg with digestible phosphorus of 9.3,9.3 and 7.8 g/kg,respectively.Broken-line analysis indicated that the digestible phosphorus requirement for largemouth bass were 8.9,8.7 and 9.6 g/kg based on weight gain,feed conversion ratio and vertebral phosphorus content.In conclusion,the supplementation of MCP in a diet containing 350 g/kg fish meal improved the growth and feed utilization of largemouth bass,and the digestible phosphorus requirement was suggested to be 8.7–8.9 g/kg with MCP supplementation of 15.0–15.8 g/kg.展开更多
基金supported by Project of National Natural Science Foundation of China(32172982)Project of Science and Technology of Guangdong Province(2021B0202050002)+2 种基金Project of Science and Technology of Guangdong Province(2023A1515012627)National Natural Science Foundation of China(32303014)Guangdong Basic and Applied Basic Research Foundation(2024A1515010444).
文摘Background The carnivorous fish,largemouth bass(Micropterus salmoides),has difficulty metabolizing dietary carbohydrates,frequently resulting in issues with energy metabolism and fatty liver disease.Nevertheless,the molecular mechanisms involved are still not fully understood.Results The results of high-carbohydrate(HC)diets and high-glucose(HG)treatments in largemouth bass hepatocytes showed that high-glucose causes liver damage and glycolipid accumulation.High-glucose promoted the lipogenesis process by activating AMPK/ACC/SREBP-1 pathway and reduced bile acid synthesis by downregulating cholesterol 7-hydroxylase(cyp7a1)and sterol 12-hydroxylase(cyp8b1).Concurrently,HG treatments also caused mitochondrial fission and damage by increasing the expression of dynamin-related protein 1(Drp1),leading to impaired mitochondria accumulation and mitochondria-dependent apoptosis via the p38 MAPK/Bcl-2/Casp3 pathway.Additionally,HG treatments decreased Sirt1 expression and relocated it from the nucleus to the cytoplasm,where it interacts with autophagosomes and lysosomes,inhibiting Pink1/Parkin-mediated mitophagy.This also led to the cytoplasmic translocation of Pink1 and its co-localization with Sirt1,indicating that Sirt1 regulates high glucose-induced metabolic stress by inhibiting the Pink1/Parkin mitophagy pathway.Conclusion In summary,HG treatment induces mitochondrial damage and glycolipid accumulation in largemouth bass through mechanisms involving AMPK/SREBP1/ACC1-mediated lipogenesis,bile acid metabolism,Sirt-mediated mitophagy,and p38 MAPK/Bcl-2/Casp3-activated apoptosis.
基金supported by the National Key Research and Development Program of China(2024YFD1300803).
文摘Background To more effectively address the scarcity resources and elevated costs associated with fishmeal(FM),the utilization of cottonseed protein concentrate(CPC)as an alternative in aquaculture feeds has become increasingly prevalent.However,high levels of CPC substitution for FM have been reported to suppress the growth of fish and impair intestinal health.Hydrolysable tannin(HT)has been reported to exhibit biological activities such as antiinflammatory and antioxidant activities,but whether the HT can generate positive biological effects on the intestinal health of largemouth bass(Micropterus salmoides)remains unknown.Largemouth bass(initial weight:6.03±0.01 g)were subjected to an 8-week feeding trial with three different diets:a basic diet(named as the NC),a high CPC diet(in which CPC replaced 75%of the FM protein in the NC diet,named as the HC),and an additive diet(1.25 g/kg of the HT was added to the HC diet,named as the HCH)to explore the potential benefits of HT on intestinal health.Results The HC treatment significantly reduced the weight gain rate of fish,increased the feed conversion ratio,and induced intestinal inflammation.However,the HCH treatment could alleviate the adverse impacts of the HC diet,as evidenced by the promotion of growth and feed utilization,increased activity of digestive enzymes and antioxidant capacities,downregulated expression of pro-inflammatory factors,and maintenance of the integrity of intestinal barrier.Metabolomic analysis revealed that HCH treatment could reduce the pro-inflammatory active substances produced by arachidonic acid metabolism,including prostaglandin F2α(PGF2α)and leukotriene B4(LTB4).Transcriptomic results indicated that dietary HT might alleviate intestinal inflammation by suppressing the activation of the NF-κB signaling pathway.Furthermore,correlation analysis demonstrated that the metabolites PGF2αand LTB4,derived from arachidonic acid,exhibited a significant positive correlation with the expression of genes associated with proinflammatory responses within the NF-κB signaling pathway.Conclusions The study indicates that the HT mitigates the growth retardation and intestinal inflammation resulting from the HC diet on largemouth bass.
文摘Myostatin or GDF-8, a member of the transforming growth factor-β （TGF-β） superfamily, has been demonstrated to be a negative regulator of skeletal muscle mass in mammals. In the present study, we obtained a 5.64 kb sequence of myostatin encoding gene and its promoter from largemouth bass （Micropterus salmoides）. The myostatin encoding gene consisted of three exons （488bp, 371 bp and 1779bp, respectively） and two introns （390bp and 855 bp, respectively）. The intron-exon boundaries were conservative in comparison with those of mammalian myostatin encoding genes, whereas the size of introns was smaller than that of mammals. Sequence analysis of 1.569 kb of the largemouth bass myostatin gene promoter region revealed that it contained two TATA boxes, one CAAT box and nine putative E-boxes. Putative muscle growth response elements for myocyte enhancer factor 2 （MEF2）, serum response factor （SRF）, activator protein 1 （AP1）, etc., and muscle-specific Mt binding site （MTBF） were also detected. Some of the transcription factor binding sites were conserved among five teleost species. This infunnation will be useful for studying the tran- scriptional regulation of myostatin in fish.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2021B0202020001)China Agriculture Research System of MOF and MARA(CARS-46)+2 种基金Central Public-interest Scientific Institution Basal Research Fund of CAFS(2020TD23,2020ZJTD-02)Project of Construction of Guangdong Aquatic Seed Industry Demonstration Base 2021Special Funds for Science Technology Innovation and Industrial Development of Shenzhen Dapeng New District(KJYF202101-02)。
文摘Largemouth bass(Micropterus salmoides) is an economically important fish species in North America, Europe, and China. Various genetic improvement programs and domestication processes have modified its genome sequence through selective pressure, leaving nucleotide signals that can be detected at the genomic level. In this study,we sequenced 149 largemouth bass fish, including protospecies(imported from the US) and improved breeds(four domestic breeding populations from China). We detected genomic regions harboring certain genes associated with improved traits, which may be useful molecular markers for practical domestication, breeding, and selection. Subsequent analyses of genetic diversity and population structure revealed that the improved breeds have undergone more rigorous genetic changes. Through selective signal analysis, we identified hundreds of putative selective sweep regions in each largemouth bass line. Interestingly, we predicted 103 putative candidate genes potentially subjected to selection,including several associated with growth(psst1 and grb10), early development(klf9, sp4, and sp8), and immune traits(pkn2, sept2, bcl6, and ripk2). These candidate genes represent potential genomic landmarks that could be used to improve important traits of biological and commercial interest. In summary, this study provides a genome-wide map of genetic variations and selection footprints in largemouth bass, which may benefit genetic studies and accelerate genetic improvement of this economically important fish.
基金Supported by the National Natural Science Foundation of China(No.31201985)the National Key Technology R&D Program of China(No.2012BAD26B03)
文摘Pituitary adenylate cyclase activating polypeptide （PACAP） has a wide range of biological functions. We cloned the full-length cDNAs encoding PACAP and PACAP-related peptide （PRP） from the brain of largemouth bass （Micropterus salmoides） and used real-time quantitative PCR to detect PRP- PACAP mRNA expression. The PRP-PACAP cDNA has two variants expressed via alternative splicing： a long form, which encodes both PRP and PACAP, and a short form, which encodes only PACAR Sequence analysis results are consistent with a higher conservation of PACAP than PRP peptide sequences. The expression of PACAP-Iong and PACAP-short transcripts was highest in the forebrain, followed by the medulla, midbrain, pituitary, stomach, cerebellum, intestine, and kidney; however, these transcripts were either absent or were weakly expressed in the muscle, spleen, gill, heart, fatty tissue, and liver. The level of PACAP-short transcript expression was significantly higher than expression of the long transcript in the forebrain, cerebella, pituitary and intestine, but lower than that of the long transcript in the stomach. PA CAP- long and PACAP-short transcripts were first detected at the blastula stage of embryogenesis, and the level of expression increased markedly between the muscular contraction stage and 3 d post hatch （dph）. The expression of PACAP-long and PACAP-short transcripts decreased significantly in the brain following 4 d fasting compared with the control diet group. The down-regulation effect was enhanced as fasting continued. Conversely, expression levels increased significantly after 3 d of re-feeding. Our results suggest that PRP- PA CAP acts as an important factor in appetite regulation in largemouth bass.
基金supported by the Double Support Project (035–2221993229)。
文摘Background Adequate level of carbohydrates in aquafeeds help to conserve protein and reduce cost. However, studies have indicated that high-carbohydrate(HC) diet disrupt the homeostasis of the gut–liver axis in largemouth bass, resulting in decreased intestinal acetate and butyrate level.Method Herein, we had concepted a set of feeding experiment to assess the effects of dietary sodium acetate(SA) and sodium butyrate(SB) on liver health and the intestinal microbiota in largemouth bass fed an HC diet. The experimental design comprised 5 isonitrogenous and isolipidic diets, including LC(9% starch), HC(18% starch), HCSA(18% starch;2 g/kg SA), HCSB(18% starch;2 g/kg SB), and HCSASB(18% starch;1 g/kg SA + 1 g/kg SB). Juvenile largemouth bass with an initial body weight of 7.00 ± 0.20 g were fed on these diets for 56 d.Results We found that dietary SA and SB reduced hepatic triglyceride accumulation by activating autophagy(ATG101, LC3B and TFEB), promoting lipolysis(CPT1α, HSL and AMPKα), and inhibiting adipogenesis(FAS, ACCA, SCD1 and PPARγ). In addition, SA and SB decreased oxidative stress in the liver(CAT, GPX1α and SOD1) by activating the Keap1-Nrf2 pathway. Meanwhile, SA and SB alleviated HC-induced inflammation by downregulating the expression of pro-inflammatory factors(IL-1β, COX2 and Hepcidin1) through the NF-κB pathway. Importantly, SA and SB increased the abundance of bacteria that produced acetic acid and butyrate(Clostridium_sensu_stricto_1). Combined with the KEGG analysis, the results showed that SA and SB enriched carbohydrate metabolism and amino acid metabolism pathways, thereby improving the utilization of carbohydrates. Pearson correlation analysis indicated that growth performance was closely related to hepatic lipid deposition, autophagy, antioxidant capacity, inflammation, and intestinal microbial composition.Conclusions In conclusion, dietary SA and SB can reduce hepatic lipid deposition;and alleviate oxidative stress and inflammation in largemouth bass fed on HC diet. These beneficial effects may be due to the altered composition of the gut microbiota caused by SA and SB. The improvement effects of SB were stronger than those associated with SA.
基金Supported by National Natural Science Foundation of China(No.31201985)National Key Technology Support Program of China(2012BAD26B03)"948"Key Program of the Ministry of Agriculture of China(2011-G12)
文摘High density lipoprotein binding protein （HBP） plays an important role in lipid metabolism of animals. Lipids are indispensable energy materials for fi- shes, especially for carnivorous fishes with low utilization efficiency of carbohydrates. The single nucleotide polymorphism （SNP） of HBP gene may affect the fat metabolism, thereby exerting an effect on the growth traits of largemouth bass （Micropterus salmoides）. Investigating the correlations between SNP and growth traits can provide candidate markers for molecular marker-assisted selection. In this study, partial genomic fraganents of HBP gene （ GenBank accession number： KF652241 ） were amplified based on the sequences of an available contig in the EST-SNP database of largemouth bass. Three SNP mutation loci were identified in the 3＇ non-ceding region of HBP gene by direct sequencing, including H1 （G ＋ 2782T）, 142 （T ＋ 2817C） and H3 （G ＋ 2857A）. Three SNP loci of 165 randomly selected largemouth bass individuals were detected and genotyped by SnaPshot assay. Genetic structure was analyzed by POPGENE32 software. By using spssl7.0 software, a general linear model （GLM） was established for correlation analysis between different genotypes at SNP loci of HBP gene and various growth traits. The results showed that three SNP loci were in Hardy-Weinberg equilibrium state. To be specific, loci H1 and H2 formed two haplotypes （ A and B）, and three geno- types （AA, AB, and BB） were observed; loci H1, H2 and H3 formed six diplotypes （DI, I）2, D3, D4, D5 and D6）. According to the correlations between dif- ferent genotypes and various growth traits, the body weight and total length of largemouth bass individuals with genotype BB were significantly higher than those of individuals with genotype AB （ P 〈 0.05 ） ; the body weight and total length of largemouth bass individuals with diplotype D6 were significantly higher than those of individuals with diplotype D4 （P 〈0.05）. In this study, SNP markers correlated with growth traits were obtained in the 3＇ non-coding region ofHBP gene in large-mouth bass, which could be used as candidate genetic markers for subsequent molecular marker-assisted selection breeding of largemouth bass.
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Global warming threatens freshwater ecosystems and compromises fish survival.To elucidate the role of miRNAs in the livers of heat stressed largemouth bass,juvenile fish was subject to heat stress under 37°C.Both mRNA-seq and miRNA-seq were conducted on the liver tissues under control and heat stress conditions.Differential gene expression analysis and enrichment analysis were performed on mRNA and miRNA expression profiles.A total of 406 differentially expressed genes(DEGs)were discovered,of which 212 were up-regulated and 194 were down-regulated.Most of the DEGs were significantly implicated in the regulation of“protein processing in endoplasmic reticulum”,“proteasome”,“steroid biosynthesis”,and“ornithine decarboxylase inhibitor activity”pathways.In addition,47 differentially expressed miRNAs(DEMs)were identified in largemouth bass livers under heat stress,including 21 up-regulated and 25 down-regulated miRNAs.A negatively regulated miRNA-mRNA network including 12 miRNAs and 19 mRNAs was constructed with DEMs involved in“protein degradation”,“calcium ion regulation”,“cell apoptosis”,and“lipid metabolism”.Moreover,this study indicated novel-miR-144 activated the IRE1 signaling pathway by targeting txndc5 to induce liver apoptosis in largemouth bass under heat stress.This study revealed the involvement of miRNA regulation in largemouth bass in response to heat stress.
文摘Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (<span style="white-space:nowrap;"><i></span>Micropterus salmoides<span style="white-space:nowrap;"></i></span>) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow (<span style="white-space:nowrap;"><i></span>Pimephales promelas<span style="white-space:nowrap;"></i></span>) forage during 2015. At harvest, age-0 bass yield was 4.5 times greater and average fish length was 38 mm longer, in the pond that received fathead minnow. In 2016, a second study evaluated the timing of minnow supplementation that included earlier stockings of small fathead minnow (<30 mm) compared to delayed supplementation with larger (>30 mm) minnows. With earlier supplementation, bass yield was 2.3 times greater and fish averaged 14 mm longer at harvest. Bass survival was approximately 38% higher during 2015 when supplementation occurred and 25% higher during 2016 when minnow supplementation began earlier. Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production.
文摘An understanding of the relative importance of natural factors and management practices affecting largemouth bass (Micropterus salmoides) abundance is key for enhanced angling. Standardized fish surveys, management practices, and environmental data were available from 42 man-made, inland lakes between 1960 and 1991. Management practices tested were largemouth bass stocking, lake rehabilitation, water level manipulation, aquatic vegetation controls, small fish removal, and changes in length limits of harvestable fish. Environmental factors not controlled by management were spring water influx, growing and cooling degree days, and snow depth. Lake rehabilitation (complete drainage and reflooding), changes in length limits, and aquatic vegetation controls were the only significant factors affecting largemouth bass abundance. The largest effects were due to lake rehabilitation, which increased next-year young largemouth bass numbers by 566% on average, and more restrictive limits on harvestable size, with an increase of up to 440% in adult numbers.
文摘Excessive largemouth bass ( Micropterus salmoides ) recruitment in small impoundments leads to density-dependent growth depression, causing populations to have length distributions skewed towards smaller fish. To address this issue, we conducted three trials that evaluated stocking all female largemouth bass (F-LMB) in two small Alabama ponds (0.5 and 2.0 ha) where the drainage basin was isolated. Age-1 fish were individually identified for sex using a micro pipette inserted in the urogenital pore, tagged, and stocked at 38-40 F-LMB/ha into ponds that contained pre-established sunfish ( Lepomis spp.) populations. Female largemouth bass were collected with electrofishing, angling, and rotenone over a 2.5- to 5-year period among the three trials. Sex was correctly identified for 179 of the 180 F-LMB stocked. One male was detected in the first trial which resulted in successful largemouth bass reproduction and this trial was terminated after two years. Growth was rapid the first 2 years after stocking as 3-year-old fish reached an average of 429 to 459 mm and 1.37 to 1.66 kg in all 3 trials. However, 2 years after stocking, growth was nil in the second trial even though relative weights of F-LMB were generally greater than 100. In this second trial, removal of about 30% of the F-LMB inhabiting the pond and stocking small Nile tilapia Oreochromis niloticus (25 - 75 mm) resulted in average weights increasing from 1.30 to 2.34 kg in 1 year. Growth of F-LMB continued in the third trail, and average size approached 500 mm and 2.2 kg three years after stocking. Annual survival rates of F-LMB were high and ranged from 0.78 to 0.93 among the 3 trials. Stocking F-LMB offers an attractive alternative in ponds to create a low density largemouth bass population that displays fast growth and high survival when catch-and-release fishing is primarily practiced.
文摘Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable amino acids and different carbohydrate to lipid ratios influence those systems. Therefore, the present study aimed to evaluate whether arginine （Arg） intake and carbohydrate to lipid ratios would affect expression of GH, IGF-Ⅰ and INS in largemouth bass.
基金funded by the National Key Research and Development Program of China(2023YFD2400600).
文摘To trigger compensatory growth(CG)with novel protein sources in juvenile largemouth bass(Micropterus salmoides)(initial weight:4.73±0.04 g),Chlorella(Chlorella vulgaris,ChM),cottonseed protein concentrate(CSM),Clostridium autoethanogenum(CAP)and yellow mealworm(Tenebrio molitor,TM)were applied to completely substitute fishmeal in the diet during a four-week dietary restriction phase(the first phase).After being refed with fishmeal(FM)diet for the next four weeks(the second phase),the growth performance,proximate composition,biochemical parameters and liver condition of treatment groups(denoted as ChM,CSM,CAP,TM group,respectively)were assessed and compared with the control group(denoted as FM group),which was consistently fed with fishmeal diets.All groups exhibited different responses during restriction and refeeding phases.The CSM,CAP,and TM groups experienced initial growth reduction followed by accelerated growth,whereas the ChM group maintained steady growth.Compensation coefficient results indicated that only ChM and CSM groups achieved compensatory growth,although there was still a gap in final weight compared with FM group.Regarding the liver condition,histopathological analysis and biochemical parameters revealed a gradual increase in lipid accumulation in the FM group during the second phase,accompanied by slowing growth.The CSM,CAP,TM groups showed varying degrees of liver injury,with the CAP group exhibiting elevated serum transaminase(ALT and AST)activity and a dramatically higher content of malondialdehyde(MDA)in liver.Conversely,the ChM group possessed healthier livers,characterized by active antioxidative capacity and low content of total triglyceride(TG).Meanwhile,abnormal lipid deposition and different amino acid content were observed throughout the FM group,potentially affecting the fish quality compared with the ChM group.Overall,the results demonstrated the feasibility and potential of triggering compensatory growth by completely replacing fishmeal with Chlorella,which exhibited the showed superior performance among novel protein sources.
基金financially supported by the China Agriculture Research System of MOF and MARA(CARS-46)Lucta(Guangzhou)Flavours Co.,Ltd.
文摘The present study investigated the potential effects of an umami taste stimulator(UTS)on largemouth bass(Micropterus salmoides)fed a high plant protein diet.Two isonitrogenous and isolipidic diets were formulated with 40%fishmeal(positive control,PC)and 25%fishmeal(negative control,NC),respectively.The other three diets were supplemented with 0.10%,0.15%and 0.20%of the UTS based on NC group.Five groups of fish(mean initial weight 29.82±0.04 g)were fed twice daily for 64 days.The results indicated that feed intake,growth performance,and taste receptor and enteroendocrine-related genes expression(pyya,t1r1 and ghrl)in NC group were significantly reduced compared with PC group,which were improved with dietary supplementation of the UTS(at 0.15%and 0.20%).In addition,muscle thickness of midgut and hindgut,villus length of hindgut in the NC group were reduced compared to the PC group,but they improved with dietary UTS supplementation.Also,antioxidant capacity,and expression of genes involved in peptide and amino acid transport and target of rapamycin(TOR)pathway were reduced in the NC group compared to the PC group.However,the inclusion of UTS improved the total antioxidant capacity,superoxide dismutase and catalase compared with the NC group.Peptide and amino acid transporters(lat1,lat2,snat2 and pept2)and TOR pathway(tor,akt1,4ebp1 and s6)related genes’expression were also ameliorated by UTS addition compared to the NC group.In summary,UTS supplementation could improve the appetite,growth performance,and health status of largemouth bass,and the recommended additional amount of UTS was 0.15%-0.20%.
基金supported by the Key Research and Development Plan of Hubei province,China(2022BBA0058)the National Natural Science Foundation of China(31972797 and 32172977)the China Agricultural Research System of MOF and MARA and the Fundamental Research Funds for Central University(Project 2662023SCPY004).
文摘Frequent occurrences of extreme weather events,particularly severe temperature fluctuations,have significantly impaired the growth and health of fish and resulted in detrimental impacts on aquaculture production.Despite recognition of the crucial role that temperature plays in aquaculture,there is currently inadequate research to assess the consequences of extreme temperature fluctuations on fish health.Hence,we set up acute warming(AW)and cooling groups(AC)by increasing or decreasing water temperature by 8℃ and then gradually restoring the initial temperature(22℃),to investigate the adaptive regulation of energy metabolism,immune function,and gut microbiota in largemouth bass(Micropterus salmoides).The fish antioxidant system responded to assist their environmental adaptation:both groups showed activation of serum superoxide dismutase(SOD)and catalase(CAT)secretion,and a significant increase in serum total antioxidant capacity(T-AOC)(P<0.05).Distinct metabolic strategies were employed to cope with sudden environmental perturbations:upon experi-encing a temperature decrease(AC1),largemouth bass exhibited a significant increase in serum triglyceride(TG)and cholesterol(CHOL)levels(P<0.05),coupled with a reduction in blood glucose levels(P<0.05).However,a considerable reduction in serum TG and CHOL levels was observed after acute warming stage(AW1)(P<0.05).Following the recovery of temperature,both groups demonstrated a tendency towards normal energy metabolism(CON).Compared to the AW group,the immune function of largemouth bass in the AC group was dramatically affected:alkaline phosphatase(AKP),aspartate transaminase(AST),and alanine transaminase(ALT)increased significantly,while lysozyme(LZM)decreased significantly when the temperature dropped sharply(P<0.05).After the temperature fluctuations,there were apparent changes in the gut morphology and microbiota of largemouth bass.Microbial functional analysis using the KEGG database revealed apparent al-terations in microbial biological functions,especially during the cooling fluctuation(AC).The results indicated that dramatic weather changes,particularly extreme cold,may be detrimental to the health and welfare of largemouth bass.
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This study was financially supported by the Blue Granary Project(2019YFD0900203)from the Ministry of Science and Technology of China.
文摘This study investigated the effects of replacing fishmeal with Clostridium autoethanogenum protein(CAP)on growth,feed utilization and intestinal histology of largemouth bass(Micropterus salmoides).The control diet contained 350 g/kg fishmeal,and then dietary fishmeal was decreased to 300 g/kg,250 g/kg,200 g/kg,150 g/kg and 100 g/kg by CAP inclusion,respectively(FM-30,FM-25,FM-20,FM-15,FM-10).The largemouth bass(110.0±1.0 g)were fed one of the six diets for 8 weeks.The groups of FM-30,FM-25 and FM-20 showed the similar weight gain(WG)and feed conversion ratio(FCR)to the control(P>0.05),while the WG of FM-10 group was decreased by 15.9%,and FCR increased by 0.12 when compared to the control(P<0.05).FM-15 and FM-10 groups had lower protein retention,lower villus height in intestine and higher serum malondialdehyde content than the control(P<0.05).The protease activity in FM-20,FM-15 and FM-10 groups was lower than that in the control(P<0.05),but no difference was observed in crude protein digestibility among groups(P>0.05).In conclusion,CAP could replace 150 g/kg fishmeal in diet(350 g/kg fishmeal)without adverse effects on growth,feed utilization and intestinal histology of largemouth bass.
基金funded by National Natural Science Foundation of China(NSFC 32061133004 and 31925038)。
文摘Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry.This study aimed to investigate the effects of bile acids(BAs)on gut barriers in Micropterus salmoides.A germ-free(GF)zebrafish model was employed to elucidate the effects of the direct stimulation of BAs and the indirect regulations mediated by the gut microbiota on gut barrier functions.Four diets were formulated with BAs supplemented at 0,150,300 and 450 mg/kg,and these 4 diets were defined as control,BA150,BA300 and BA450,respectively.After 5 weeks of feeding experiment,the survival rate of fish fed with BA300 diet was increased(P<0.05).Histological analysis revealed an improvement of gut structural integrity in the BA150 and BA300 groups.Compared with the control group,the expression of genes related to chemical barrier(mucin,lysozyme and complement 1)and physical barrier(occludin and claudin-4)was increased in the BA150 and BA300 groups(P<0.05),and the expression of genes related to immunological barrier(interleukin[IL]-6,tumor growth factorβ,IL-10,macrophage galactosetype lectin and immunoglobulin M[Ig M])was significantly increased in the BA300 group(P<0.05),but the expression of genes related to chemical barrier(hepcidin)and immunological barrier(IL-1β,tumor necrosis factor-a,IL-6 and arginase)was significantly decreased in the BA450 group(P<0.05).Gut microbiota composition analysis revealed that the abundance of Firmicutes was augmented prominently in the BA150 and BA300 groups(P<0.05),while that of Actinobacteriota and Proteobacteria showed a downward trend in the BA150 and BA300 groups(P>0.05).The results of the gut microbiota transferring experiment demonstrated an upregulation of gut barrier-related genes,including immunoglobulin Z/T(Ig Z/T),IL-6,IL-1βand IL-10,by the gut microbiota transferred from the BA300 group compared with the control(P<0.05).Feeding the BA300 diet directly to GF zebrafish resulted in enhanced expression of Ig M,Ig Z/T,lysozyme,occludin-2,IL-6 and IL-10(P<0.05).In conclusion,BAs can improve the gut barriers of fish through both direct and indirect effects mediated by the gut microbiota.
基金study was supported by Guangdong province key field R&D program project(No.2020B0202010001)Shanghai collaborative innovation for aquatic animal genetics and breeding.
文摘An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass.A total of 600 healthy fish(12.96±0.07 g)were fed diets containing varying levels of vitamin K3 at 0.78(K0),5.80(K5),10.82(K10),15.84(K15),and 20.85(K20)mg/kg with four replicates per level.Results showed that dietary vitamin K3 enhanced growth,with weight gain rate and specific growth rate in K15 trials significantly higher than K0 trials(P<0.05).No significant difference was observed in the content of crude protein,crude lipid,moisture,ash,and phosphorus in muscle tissue(P>0.05).However,the supplementation of vitamin K3 significantly contributed to calcium accumulation in muscle tissues and vertebrae(P<0.05)and increased red blood cell counts(P<0.05).The blood coagulation time decreased significantly with increasing dietary vitamin K3 from 0.78 to 10.82 mg/kg(P<0.05)before stabilizing(P>0.05).The antioxidant capacity was improved with the addition of vitamin K3,which was inconsistent with the changes in malondialdehyde and MK-4(a form of menaquinone)within liver and serum,suggesting that the toxicity of excessive artificial vitamin K3 may account for this difference.Using regression analysis,the appropriate dietary vitamin K3 levels within a largemouth bass diet was determined to be in the range of 9.93-15.22 mg/kg,which will provide a reference for the preparation of vitamin premix and artificial diet for largemouth bass.
基金Research and Supporting Platform of Efficient Aquaculture(A1-3201-19-3003).
文摘The present study was conducted to estimate the optimum requirement of phosphorus in practical diets for largemouth bass(Micropterus salmoides).Six iso-energetic and iso-nitrogenous diets were formulated with the supplementation of monocalcium phosphate(MCP)of 0,5,10,15,20 and 25 g/kg in basal diet containing 350 g/kg fish meal,respectively.The digestible phosphorus of the six diets was measured as 5.7,6.7,7.8,8.7,9.3 and 10.0 g/kg,respectively.Each diet was randomly fed to triplicate groups of 25 juvenile fish(initial body weight,16.0±0.2 g)for 60 days.The results showed that weight gain increased,and feed conversion ratio decreased with the increase of dietary phosphorus.When dietary MCP exceeded 15 g/kg(digestible phosphorus of 8.7 g/kg),the WG and FCR were maintained at the similar values.The crude ash,phosphorus and calcium contents in whole body,apparent digestibility of phosphorus and protein retention also increased with the increasing phosphorus level in diets.Vertebrae phosphorus and calcium levels and plasma phosphorus showed no further increase when dietary MCP reached 20,20 and 10 g/kg with digestible phosphorus of 9.3,9.3 and 7.8 g/kg,respectively.Broken-line analysis indicated that the digestible phosphorus requirement for largemouth bass were 8.9,8.7 and 9.6 g/kg based on weight gain,feed conversion ratio and vertebral phosphorus content.In conclusion,the supplementation of MCP in a diet containing 350 g/kg fish meal improved the growth and feed utilization of largemouth bass,and the digestible phosphorus requirement was suggested to be 8.7–8.9 g/kg with MCP supplementation of 15.0–15.8 g/kg.
