[Objective]To solve the problems of imaging blurring and low detection accuracy in complex background of underwater target images,this study proposes an underwater target detection algorithm which integrates multiple attention mechanisms and Wise-IoUv3.[Method]Firstly,a multi-scale feature enhancement mechanism was designed in the backbone network,omni-dimensional dynamic convolution(ODConv)was used to replace some convolutions,and an efficient-scale attention mechanism(EMA)was introduced to enhance the backbone network's ability to extract features of blurred targets and small targets.Secondly,the spatial pyramid pooling-fast(SPPF)module was improved by adding an average pooling branch to supplement spatial information and enhance global context awareness.In addition,the lightweight BiFormer attention mechanism was integrated into the two branches to reduce the model's computational complexity and enhance the detection performance of small targets.Then,in the prediction stage,the original loss function was replaced by Wise-IoUv3 to balance the model training results of different quality images.Finally,the original detection head was replaced by the dynamic detection head(DynamicHead)to enhance the scale perception,spatial perception and task perception ability of the detection head and improve the accuracy of object position recognition.[Result]The experimental results on RUOD and URPC datasets show that the improved algorithm increases the mean average precision by 3.6%and 1.7%respectively,compared with the benchmark methods(especially YOLOv8n);the model's parameter count and computational cost are reduced by 0.26×106 and 0.4 GFLOPs,respectively.[Conclusion]The experimental results show that the proposed method reduces the missed-detection and false-detection of blurred targets and small targets in complex situations,thus improving the detection and maintaining the model's lightweight design.
Crassostrea hongkongensis (C. hongkongensis) is one of the three most commonly cultivated oyster species in China. Seasonal hypoxia is one of the most serious threats to its metabolism, reproductive behavior, and survival. To investigate the effects of hypoxia stress on the antioxidant capacity and energy metabolism of C. hongkongensis, the total antioxidant capacity (T-AOC), glycogen content, and enzyme activities (phosphofructokinase, PFK; pyruvate kinase, PK; phosphoenolpyruvate carboxykinase, PEPCK) of oysters were determined under normoxic (DO 6 ± 0.2 mg/L) and hypoxic (DO 1.5 mg/L) conditions at 0 h, 6 h, 48 h, and 72 h. We also determined the T-AOC, glycogen content, and enzyme activities of oysters under reoxygenation (recovered to normoxia for 24 h). To further examine the potential molecular regulatory mechanism of hypoxic adaptation, a transcriptome analysis was conducted on the gill of C. hongkongensis under normoxia (N, 72 h), hypoxia (H, 72 h), and reoxygenation (R). After being exposed to hypoxia for 6 h, the T-AOC, glycogen content, and enzyme activities of PK, PFK, and PEPCK in C. hongkongensis were significantly decreased. However, after prolonging the duration of hypoxia exposure for 72 h, the T-AOC, glycogen content, and enzyme activities increased compared to that of 48 h. After 24 h reoxygenation, the T-AOC, glycogen content, and enzyme activity of PK and PFK returned to close to initial levels. In addition, a transcriptome analysis discovered 6097 novel genes by mapping the C. hongkongensis genome with the clean reads. In total, 352 differentially expressed genes (DEGs) were identified in the H vs. N comparison group (235 upregulated and 117 downregulated genes). After recovery to normoxia, 292 DEGs (134 upregulated and 158 downregulated genes) were identified in the R vs. N comparison group, and 632 DEGs were identified (253 upregulated and 379 downregulated genes) in the R vs. H comparison group. The DEGs included some hypoxia-tolerant genes, such as phosphoenolpyruvate carboxykinase (PEPCK), mitochondrial (AOX), tyramine beta-hydroxylase (TBH), superoxide dismutase (SOD), glutathione S-transferase (GST), and egl nine homolog 1 isoform X2 (EGLN1). Additionally, DEGs were significantly enriched in the KEGG pathways that are involved in hypoxia tolerance, including the metabolism of xenobiotics by cytochrome P450 pathways and the HIF-1 signaling pathway. Then, we selected the five hypoxic-tolerant candidate DEGs for real-time quantitative polymerase chain reaction (RT-qPCR) validation, and the results were consistent with the transcriptome sequencing data. These discoveries have increased our understanding of hypoxia tolerance, recovery ability after reoxygenation, and molecular mechanisms governing the responses to hypoxia in C. hongkongensis.
[Objective]The aim of this study is to study the ameliorative effect of docosahexaenoic acid-enriched phosphatidylcholine(DHA-PC)on bisphenol S(BPS)-induced liver injury in mice.[Methods]C57BL/6 mice(n = 24)were randomly divided into control group,model group and administration group with 8 mice in each group.The model group and administration group were given 5 mg·(kg·d)-1 BPS for 10 weeks,respectively,at the same time,the administration group was given 80 mg/kg DHA-PC.The protective effect of DHA-PC[80 mg·(kg·d)-1]on BPS-induced liver injury in mice was studied by monitoring the food intake and body weight of mice,liver function and liver histopathological analysis,inflammatory factors,lipids and oxidative stress in liver tissue.[Results]After BPS treatment,the body mass,liver index and epididymal fat index of mice were significantly increased(P<0.05),and after DHA-PC treatment,these indices showed a downward trend.There was no difference in food intake or energy intake among the three groups(P>0.05).Pathological results showed that the hepatic cord disappeared and focal fatty lesion occurred in the model group,while the hepatic cord recovered and central vein reappeared in the administration group.Compared with the model group,the contents of alanine aminotransferase(ALT),aspartate aminotransferase(AST),interleukin(IL)-1β,IL-6,tumor necrosis factor(TNF)-α,cholesterol(TC),triglyceride(TG),free fatty acid(NEFA),low-density lipoprotein cholesterol(LDL-C)and malondialdehyde(MDA)were significantly decreased after DHA-PC treatment(P<0.05).The contents of high-density lipoprotein cholesterol(HDL-C),total antioxidant capacity(T-AOC),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and catalase(CAT)were significantly increased after DHA-PC treatment,compared with the model group(P<0.05).[Conclusion]DHA-PC from herring roe can effectively improve BPS-induced liver injury in mice by inhibiting inflammation,improving lipid metabolism disorder and oxidative stress.
[Objective]The aim of this paper is to explore the effects of dietary phospholipid level on growth performance,antioxidant capacity,fatty acid composition and lipid metabolism of juvenile snakehead(Channa argus).[Methods]Snakehead fry with an initial body mass of(3.99±0.01)g were fed with five iso-nitrogenous and iso-lipidic diets prepared by adding 0,2%,4%,6%and 8%phospholipids to the basal diet,respectively designated as group PL0(control group),PL2,PL4,PL6 and PL8.At the end of the 43-day's culture experiment,the growth indicators,physiological and biochemical indicators and the expression levels of lipid metabolism-related genes in the liver of the juvenile snakehead were measured.[Results]1)The addition of phospholipids in the diet significantly affected the growth performance of juvenile snakehead.The final body mass and specific growth rate of the juvenile snakehead in group PL4 and group PL6 were significantly higher than those in group PL0(P<0.05).The daily feed intake(FI)and feed conversion ratio(FCR)showed a trend of decreasing first and then increasing.The FI in group PL4 was the lowest,and the FCR in group PL6 was the lowest,both of which were significantly lower than those in group PL0(P<0.05).Meanwhile,the viscerosomatic index(VSI)of the fry in group PL8 was significantly lower than that of the other groups(P<0.05).2)With the increase of dietary phospholipid level,the increase of phospholipid content in the diet significantly reduced the crude fat content of the whole fish and liver,while the moisture showed the opposite trend(P<0.05).3)With the increase of dietary phospholipid level,the malondialdehyde content in the liver decreased more significantly in groups PL6 and PL8 than in the other groups(P<0.05);the superoxide dismutase activity in the liver increased more significantly in group PL8 than in the other groups(P<0.05);the total antioxidant capacity increased first and then decreased,and the capacity in group PL2 was significantly higher than that of the other groups except PL6(P<0.05);the catalase activity was not affected by the change of phospholipid content in the diet(P>0.05).4)The addition of phospholipids in the diet significantly increased the n-3PUFA content of the fish body and liver(P<0.05).5)The addition of phospholipids also had a significant effect on the expression of lipid metabolism-related genes in the liver.The expression level of acc1,a lipid synthesis-related gene,in group PL8 was significantly lower than that in PL0 group(P<0.05);the expression levels of mgl and hsl,lipid degradation-related genes,in groups PL4 and PL6 were significantly higher than those in group PL0(P<0.05),and hsl in group PL6 was significantly higher than that in group PL0(P<0.05);the expression levels of pparα,cpt1 and aco,fatty acid oxidation-related genes,in group PL6 were significantly higher than those in group PL0(P<0.05).[Conclusion]Adding phospholipids to the diet can significantly improve the growth performance of juvenile snakehead,and enhance their antioxidant capacity and reduce lipid deposition by regulating lipid metabolism.The suitable dietary phospholipid requirement for juvenile snakehead was 5.36%.
[Objective]The aim of this study is to explore the effects of two leguminous green manure(Vicia villosa Rothvar and Vicia sativa L.)feed on the growth performance and meat quality of Procambarus clarkii.[Methods]The effects of leguminous green manure addition on growth performance,physicochemical properties and tissue structure of crayfish were analyzed after 60 days of feeding with five feed treatment groups(group T1:V.villosa,group T2:V.sativa,group T3:specialized feed,group T4:V.villosa + specialized feed,group T5:V.sativa + specialized feed).[Results]The results showed that the protein contents of V.villosa and V.sativa were 27.80%and 25.00%,the crude fiber contents of both were 22.60%,and the contents of aspartic acid and leucine were relatively high.After 60 days of feeding,compared with feeding the specialized diet(group T3),there was no significant change in the survival rate of crayfish in different groups(76.7%-80.0%,P>0.05),but the mass gain rate increased significantly by 8.13%,32.92%and 27.95%in groups T1,T4 and T5,respectively(P<0.05),and the meat gain rate increased significantly by 9.29%in group T2(P<0.05);the pressurized water loss rate significantly decreased by 20.6%and 18.8%in groups T4 and T5,respectively(P<0.05),and the color and lustre increased to some extent in all groups except for a decrease in the L* value in group T1,and the crayfish meat muscle fiber interstitial space decreased and shrimp meat became more compact in groups T4 and T5.[Conclusion]The feed mixture was better than the specialized feed or leguminous green manure alone,and the growth performance and meat quality of crayfish were better fed by V.sativa + specialized feed than V.villosa + specialized feed.
[Objective]The aim of this study is to investigate the selection of temperature,CO2 concentration and transport time during CO2-assisted simulated transport for keeping alive largemouth bass(Micropterus salmoides),and to evaluate the changes of blood biochemical indexes and muscle nutrients of largemouth bass during simulated transport.[Method]Twenty largemouth bass were randomly taken from the transient tank and placed in a glass aquarium containing 15 L of aerated experimental water.A one-way experiment was conducted to determine the optimal transport temperature and CO2 concentration using the survival rate as an indicator.The water and blood samples were taken at 0,12,24,36 and 48 h of the simulated transportation to determine the water quality,blood biochemical indexes and muscle nutrient composition.[Result]Largemouth bass were anesthetized by CO2 for 15.23 min at 7℃and 10.33 min at 14℃,and resuscitation after anesthesia took 10.20 min at 7℃and 3.53 min at 14℃.After the one-way experiment,the optimal transport temperature was determined to be 15℃,and the optimal CO2 anesthesia concentration was 4.8 and 6.8 g/L.Under these conditions,the survival rate of largemouth bass was better than that of the simulated transport with O2 only,which resulted in better muscle nutrition,and the survival rate of largemouth bass was 100%at 36 h of simulated transport.At 36 h of simulated transport,serum cortisol and glucose levels,and lactate sehydrogenase activity were significantly higher(P<0.05)than before transport.Aspartate aminotransferase activity,alanine amiotransferase activity,blood urea nitrogen and creatinine content were significantly lower than that before transportation(P<0.05).Lactic acid content in muscle was significantly higher than that before transportation(P<0.05),and glycogen and protein content were significantly lower than that before transportation(P<0.05).In the control group,the serum content of aspartate aminotransferase activity,alanine amiotransferase activity,blood urea nitrogen and creatinine content was significantly higher than that of the CO2-treated group(P<0.05),which indicated that CO2 anesthesia could alleviate the hepatic and renal injuries caused by the stress in transportation.[Conclusion]When CO2 anesthetized largemouth bass are transported,the transport time should be within 36 h.
[Objective]To explore the effects of photoperiod and vitamin concentration on the growth and material production of Pavlova sp.,in order to provide the experimental basis for determining the optimal culture conditions of Pavlova sp.[Method]The two-factor experiment of vitamin concentration and photoperiod was conducted by culturing Pavlova sp.for 14 days.The contents of pigment,lipid,protein and carbohydrate in the alga cells were measured and the fatty acid composition and biodiesel performance were analyzed.[Result]The optimal photoperiod for the growth of Pavlova sp.was 16 h∶8 h.Under the condition of 1V 16 h∶8 h.The biomass dry weight and protein production of Pavlova sp.were the highest,which were 501.50 and 55.54 mg·L-1,respectively.Under the condition of 8V 8 h∶16 h,fucoxanthin content and production were the highest,which were 6.21 mg·g-1 and 2.60 mg·L-1,respectively.The highest lipid content and production were 30.18%and 123.87 mg·L-1 under 8V 24 h∶0 h and 8V 16 h∶8 h,respectively.The optimal photoperiod for EPA production was 8h∶16h.Under the condition of 1V 8 h∶16 h,the proportion of eicosapentaenoic acid(EPA)reached 14.56%.Under the condition of 4V 24 h∶0 h,the cetane number(CN)of biodiesel reached 53.98,while the degree of unsaturation(DU)and iodine value(IV)were the lowest.[Conclusion]Compared with vitamin concentration,photoperiod was more important for the culture of Pavlova sp..Photoperiod not only affected the growth of Pavlova sp.,but also significantly affected its material production,and could change the fatty acid composition and biodiesel performance of Pavlova sp.
[Objective]The aim of this study is to investigate the effects of glycosylation on the antioxidation and amino acid composition of products after in vitro digestion of mackerel(Scomber japonicus)fish floss.[Method]The fish floss fried with sucrose,glucose,xylose,fructose,and galactose were digested in vitro,respectively,and the digestibility after one-and two-step digestion were studied.The particle size,antioxidant activity,and amino acid composition of digestive products and the changes of digestibility were further analyzed by SDS-PAGE of digestive products.[Result and Conclusion]Except for xylose fish floss,the digestibility of fish floss with sucrose,glucose,fructose,and galactose were significantly improved compared with no sugar fish flos(P<0.05).Particle size analysis showed that the molecular diameter of digestive products after gastrointestinal two-step digestion was smaller than that after gastric digestion.Antioxidant analysis showed that with the increase in concentration of fish floss digestive product,the antioxidant activity of fish floss digestive products also increased,and the antioxidant activity of gastric digestive products was higher than that of gastrointestinal digestive products.Among them,xylose fish floss digestive products had the strongest antioxidant activity.It can be seen from the amino acid composition that the content of essential amino acids in total amino acid of the digestive products of gastrointestinal digestion was more than 35%,which had a higher nutritional value.At the same time,the antioxidant amino acids in total amino acid of the digestive products accounted for more than 80%,indicating that the antioxidant activity of the digestive products of fish floss was related to its amino acid composition.
[Objective]To explore the anesthetic effect of eugenol on Sebastiscus marmoratus,and to provide reference for the tagged releasing technology of S.marmoratus.[Method]A total of 12 eugenol concentration groups of 10-180 mg/L were set up to observe the final anesthesia stage that the fish could reach at different concentrations,and the appropriate concentration range was preliminarily screened.The effective anesthesia concentration was further determined according to the anesthesia recovery time and recovery rate.On this basis,the comparative study of air exposure test was carried out.[Result]S.marmoratus could reach stage IV anesthesia within 3 min at a concentration of more than 30 mg/L,and no death and obvious stress response occurred within 5 min at a concentration of less than 80 mg/L.The suitable concentration range was 30-80 mg/L after preliminary screening.According to the commonly used effective anesthesia mass concentration selection criteria,combined with the resuscitation test,the effective anesthesia concentration of S.marmoratus was 40-50 mg/L.At this time,S.marmoratus could be anesthetized within 3 min,resuscitated within 7 min,and the survival rate was 100%after 15 min of anesthesia.All the S.marmoratus survived in the solution less than 150 mg/L for 5 min,and died in more than 5 min;In the air exposure test at a concentration of 40 mg/L,the average recovery time was the shortest at 15 min,and then the average recovery time gradually increased with the extension of air exposure time.Therefore,it is considered that S.marmoratus has recovered at 15 min in the air.In order to avoid the stress of the fish,the water-leaving test operation should be completed within 15 min.[Conclusion]The suitable anesthetic concentration of eugenol for the marker specification of S.marmoratus[body length(88.12±4.87)mm)]is 40-50 mg/L,and the operation of leaving water should be controlled within 15 min.If rapid anesthesia is required,50-150 mg/L can be selected,and the anesthesia time should be controlled within 5 min to avoid anesthesia death.
[Objective]To investigate the effects of guanidinoacetic acid(GAA)on growth performance,digestion and absorption,metabolism and antioxidant capacityantioxidant capacity of Sebastes schlegelii and to provide theoretical basis for the application of GAA in the cage culture of S.schlegelii.[Method]Five iso-nitrogenous and iso-lipid experimental diets were prepared by adding GAA with mass fraction of 0.00%(D0),0.01%(D1),0.02%(D2),0.04%(D3),0.08%(D4)respectively to the basal diet and fed to five groups of experimental rockfish[initial mass(125.00±1.00)g]for seven weeks.Growth performance,antioxidant,serum biochemical indices and liver glycometabolism of S.schlegelii were determined.[Result]The results in the current study indicated that:(1)Compared with control group(D0),groups D1,D2,D3 and D4 significantly increased the body weight gain rate,specific growth rate and protein efficiency,and decreased the feed coefficient(P<0.05).(2)There were no significant differences in moisture,crude protein,crude lipid and ash content of whole fish among the five groups(P>0.05).(3)Compared with group D0,the activities of intestinal trypsin and amylase in groups D1,D2,D3 and D4 were significantly increased(P<0.05),while the activities of lipase in groups D3 and D4 were significantly increased(P<0.05).(4)Compared with group D0,serum triglyceride and high density lipoprotein cholesterol concentrations in group D3 were significantly increased(P<0.05).(5)Compared with group D0,T-AOC content in liver in groups D1,D2,D3 and D4 was significantly increased(P<0.05),malondialdehyde content was significantly decreased in groups D1,D2,D3 and D4(P<0.05),and SOD activity in groups D2,D3 and D4 was significantly increased(P<0.05).(6)Compared with group D0,the PK activity and CK activity in liver of groups D1,D2,D3 and D4 were significantly decreased(P<0.05),the PFK activity was significantly decreased in group D3(P<0.05),and the Cr content in liver of groups D2,D3 and D4 was significantly increased(P<0.05).[Conclusion]With the weight gain rate as the evaluation indictor,the appropriate supplemental level of GAA in the diet of S.schlegelii is 0.04%.The addition of suitable GAA(0.04%-0.08%)in the diet can improve the intestinal digestive enzyme activity of S.schlegelii,and regulate the content of metabolites to exert antioxidant effect and energy-regulating effect.
[Objective]The aim of this study is to investigate the differences in energy metabolism between red and white muscle tissues of yellowfin tuna(Thunnus albacares)of different body mass.[Methods]The glycogen content,anaerobic and aerobic metabolic key enzyme activity and metabolism-related gene expression were measured in red and white muscle of small fish(0.85±0.03)kg,middle fish(9.77±0.15)kg and large fish(19.63±0.37)kg were measured.[Results]1)Glycogen content in red muscle was the highest in large fish group and the lowest in small fish group(P<0.05).And the content of glycogen in white muscle was the highest in middle fish,and glycogen content in red muscle of different body mass groups were extremely significantly higher than that in white muscle(P<0.01).2)The activity of anaerobic metabolism key enzymes,including hexokinase(HK),pyruvate kinase(PK),lactate dehydrogenase(LDH)and phosphofructokinase(PFK)in red and white muscle of large fish group were significantly higher than those in small and middle fish(P<0.05),and the activities of HK,PK,LDH and PFK in white muscle of large fish group were significantly higher than those in red muscle(P<0.05);The activity of aerobic metabolism key enzymes,including citrate synthase(CS),succinate dehydrogenase(SDH)and malate dehydrogenase(MDH),were much higher in large fish group than in the other two groups(P<0.05).And CS and SDH activities in red muscle were significantly higher than those in white muscle tissue in large fish group(P<0.05).3)There were significant differences in the expression of the hk,sdh and mdh genes in the red muscle,with the highest expression in the large fish group(P<0.05),the ldh and pk gene expressions had no correlation with body mass,the expression of cs and pfk gene were higher than other two groups(P<0.05);The expression levels of sdh and mdh genes in white muscle with different body mass were significantly different(P<0.05),the hk,pk and cs gene expressions in middle fish group were significantly higher than those in other groups(P<0.05),but pfk gene expression was not significantly different,and the ldh gene expression was the highest in large fish group.The expressions of cs and sdh genes in red muscle were significantly higher than those in white muscle in the large fish group(P<0.01),and the expressions of hk,pk and ldh genes in white muscle were extremely higher than those in red muscle in the middle and large groups(P<0.01).4)Body mass was the main factor affecting glycogen content and enzyme activity.[Conclusion]Tuna muscle glycogen content,anaerobic and aerobic metabolic enzyme activity and gene expression are influenced by changes in fish body mass.
[Objective]This study aimed to investigate the monoamine oxidase(MAO)inhibitors from the secondary metabolites of marine Aspergillus terreus C23-3 and their inhibitory types,and investigate the potential MAO inhibitory activity and structure-activity relationship of butyrolactone analogs by computer simulation to develop MAO inhibitors.[Method]The bioactive compound was obtained by bioactivity-guided chromatographic separation.Its structure was identified by nuclear magnetic resonance spectrometry,mass spectrometry and circular dichroism analyses.The inhibition of the compounds on monoamine oxidase was assayed by colorimetric method in microtiter plates.Autodock vina was used to evaluate the butyrolactone I analogs for monoamine oxidase inhibitory potentials.[Result]1)An active compound,butyrolactone I,was isolated and identified.2)The inhibitory effect of butyrolactone I on monoamine oxidases A and B was reversible and noncompetitive,the semi-inhibition concentrations(IC50)were 21.45 μmol/L and 24.16 μmol/L respectively,the inhibition constant Ki was 6.27 μmol/L and 12.61 μmol/L respectively.3)Molecular docking showed that butyrolactone I could form multiple hydrogen bonds with amino acid residues of MAOs.Aspvinone-type butyrolactone analogs,which have α,γ-biaryl substituted five-member lactone ring and benzopyran or benzofuran groups,scored lower on the minimal binding affinity with monoamine oxidases in virtual screening.[Conclusion]Butyrolactone I is a reversible inhibitor of monoamine oxidase,and its inhibition to monoamine oxidase is noncompetitive.Fungal butyrolactones are new source of MAO inhibitors.
[Objective]The present study was conducted to investigate the effects of the mass ratio of dietary docosahexaenoic acid to eicosapentaenoic acid(DHA/EPA)on growth performance,body composition and digestive enzymes activities of grouper(Epinephelous coioides)larvae.[Method]Five isoproteic(58%)and isolipidic(16%)diets were formulated with graded DHA/EPA(0.82,1.28,1.67,2.00 and 2.33),named group 0.82,1.28,1.67,2.00 and 2.33,respectively,through adjusting the content of DHA enriched oil and EPA enriched oil.A 4-week feeding trial was conducted on larval grouper with an initial weight of(70±0.2)mg.Each group had 3 replicates and was fed to apparent satiation 5 times daily.[Results]The ratio of dietary DHA/EPA produced no significant difference on the survival rate of larval grouper(P>0.05),while the larvae in group 1.67 obtained significantly higher growth than other groups(P<0.05).The increase of dietary DHA/EPA significantly elevated crude lipid content of grouper larvae(P<0.05).Meanwhile,crude protein content of larvae in group 1.67 was significantly higher(P<0.05),while the moisture content in group 1.67 was significantly lower than other groups(P<0.05).The fatty acid composition of whole fish body and muscle was well correlated with dietary fatty acid profile,and DHA was easier to be retained compared to EPA(P<0.05).The activity of digestive enzymes was significantly affected by the ratio of dietary DHA/EPA(P<0.05).The activity of pepsin and intestinal trypsin in grouper larvae in group 1.67 was statistically higher than that of other groups(P<0.05).However,the increase of the ratio of dietary DHA/EPA significantly reduced the activity of intestinal amylase,and the intestinal lipase activity in groups 0.82 and 2.33 was significantly lower than that of other groups(P<0.05).[Conclusion]Optimal ratio of dietary DHA/EPA significantly improved the growth performance,and promoted the development of digestive tract of larval grouper,and dietary DHA/EPA ratio should be maintained at 1.67 for the micro-diets for this grouper.
[Objective]In order to strengthen the early and rapid diagnosis and screening of Vibrio harveyi,a rapid detection method was explored.[Method]We established a rapid visual loop-mediated isothermal amplification(LAMP)method for detection of V.harveyi by choosing the outer membrane channel protein gene Toic of V.harveyi as the target gene,designating the calcein as the indicator of detection results,optimizing the reaction system,reaction time and reaction temperature,and detecting its specificity and sensitivity.[Results]The shortest detection time was 35 min.The detection sensitivity was 100 fg/mL.The specificity of the LAMP method was strong and no cross-reaction with other 8 kinds of Vibrio and Staphylococcus aureus.The practical test results showed that this LAMP method could accurately and specifically detect V.harveyi in fish tissues infected with V.harveyi.[Conclusion]This study successfully established a visual LAMP method for rapid detection of V.harveyi with simple equipment,simple operation,rapid reaction,strong specificity,high sensitivity,and visual results.This method is suitable for the early and rapid diagnosis of V.harveyi infection in Epinephelus,which provides technical support for further popularizing this technology in the field of disease monitoring of grouper and other aquatic animals.
[Objective]The aim of this study is to reveal the effect of salting time on sensory quality and texture state of dried low-sodium-salted Lutianus erythropterus,and to provide theoretical basis for the processing optimization of dried low-sodium-salted fish products with high quality.[Method]The low-sodium salt was prepared with 85%NaCl and 15%KCl according to the mass fraction,and the application of overcoating salting using low-sodium salt at 30%mass fraction of fish,water desalination and sun-drying processing,the effects of different salting time(2,4,6,8,10 h)on sensory score,chromacity,texture,muscle fiber structure,mass fraction of salt and water,water distribution and migration of dried low-sodium-salted L.erythropterus were investigated.[Result]With the increasing of salting time,the sensory indicators of saltiness,umami,salted-fish flavor,hardness,chewiness and golden color of dried fish were significantly increased(P<0.05).With the increasing of salt,the moisture inside the dried fish gradually migrated outward when the binding between protein and moisture enhanced,and the muscle fibers eventually contracted intensively.The bright-yellow chroma,chewiness,mass fraction of NaCl and water fugacity of dried fish decreased significantly after salting for more than 8 hours(P<0.05),while the greyish-green chroma increased significantly.[Conclusion]Low-sodium salting time has a significant effect on the sensory and texture quality of dried low-sodium-salted L.erythropterus.Low-sodium salting for 8 hours can ensure the better sensory quality and texture state of dried low-sodium-salted fish.
[Objective]The purpose of this study is to investigate the effects of a composite water-soluble additive(taurine,vitamin C,vitamin E,glutamine and sodium glutamate)on water quality,and on biochemical parameters and tissue structure of juvenile Ictalurus punctatus during transportation.[Methods]Different mass concentrations of the composite water-soluble additive(named F-20%,F-40%,F-60%,F-80%,F-100%groups)were added to the water,with no additive group as the control group.Subsequently,a 14-hour transportation simulation was conducted,and the water quality(total ammonia nitrogen,pH),serum and liver biochemical parameters as well as tissue structure changes during the transportation simulation(0,5,9,14 h)were evaluated.[Results]After 14 hours of transportation,the concentrations of total ammonia nitrogen in the water,cortisol in the serum,and catalase and malondialdehyde in the liver were significantly lower in the groups treated with the composite water-soluble additive compared to the control group(P<0.05).The glucose content in the serum was significantly lower in all treatment groups except for group F-20%compared to the control group(P<0.05).Except for group F-100%,the pH values of the water in the other treatment groups were significantly higher than those in the control group(P<0.05).After 14 h of transportation,the total antioxidant capacity of group F-40%was significantly lower than that of the control group and other treatment groups(P<0.05).The degree of damage to the gills and skin structure of group F-40%was lower than that in the control group.[Conclusion]The composite water-soluble additive can enhance the stress resistance of juvenile I.punctatus during transportation,reduce or even eliminate water changing operations,shorten transportation time,and maintain the health status of the juvenile I.punctatus.
[Objective]This study aimed to evaluate the effects of coated sodium butyrate in diets on growth performance,digestive capacity,antioxidant capacity and related-gene mRNA expression of large-size sea cucumber(Apostichopus japonicus),and provided theoretical basis for the rational utilization of sodium butyrate in culturing sea cucumber.[Method]Six isonitrogenous and isoenergetic diets were formulated with graded mass fraction of dietary coated sodium butyrate,0,0.05%,0.10%,0.20%,0.40%and 0.60%respectively,and the non-added group was the control group.The feeding experiment lasted for 8-week,and the initial mass of sea cucumber was(55.96±0.20)g.[Result]The results showed that no significant differences in survival rate were found among dietary treatments(P>0.05).With the increase of dietary sodium butyrate levels,the weight gain rate(WGR)and specific growth rate(SGR)increased,and then decreased after reaching the peak at the 0.40%addition group,significantly higher than those of control,0.05%,0.10%addition groups(P<0.05).The body wall of Apostichopus japonicus composition analysis showed that the crude protein,crude lipid,crude ash and moisture content of body wall were not significantly different in different groups(P>0.05).The activities of protease and lipase in intestinal tract reached their peaks at the 0.40%addition group,with no significant differences from those of 0.60%addition group(P>0.05),while significantly higher than those of control group(P<0.05).On the antioxidant capacity of sea cucumber,the activities of SOD,CAT and T-AOC in intestinal tract of 0.20%,0.40%and 0.60%addition groups were significantly higher than those of control group(P<0.05).But the MDA content in intestinal tract changed in a trend opposite to that of SOD(P<0.05).The relative expression of Rel in intestinal tract of Apostichopus japonicus was the highest in 0.40%addition group,which was significantly higher than that in the control group(P<0.05).At the same time,the relative expression of P105 in intestinal tract changed in a trend opposite to that of Rel.The relative expression of lysozyme in intestinal tract was the highest in 0.40%addition group,which was significantly higher than that in control group and 0.60%addition group(P<0.05).[Conclusion]The results showed that 0.40%coated sodium butyrate could promote the growth performance,digestibility and antioxidant capacity of large-size Apostichopus japonicus.In addition,sodium butyrate can affect the anti-inflammatory level of Apostichopus japonicus by regulating the related factors of NF-κB signal pathway,and then have a positive effect on the immune ability of the body.
[Objective]This article summarized the spatial and temporal characteristics of greenhouse gas(N2O,CO2 and CH4)emissions of four main freshwater aquaculture systems,as well as the greenhouse gas emissions and warming potential of each region,and put forward corresponding emission reduction measures to provide reference for helping the agricultural field to achieve"carbon peak and carbon neutrality"as soon as possible.[Method]Based on studies of greenhouse gas emissions from different systems,the spatial and temporal emission characteristics of different systems were summarized,and the emission coefficients of aquaculture systems were estimated.On this basis,the annual emissions and warming potential per unit area and per unit production of each province were obtained.[Result]In addition to intensive culture system,the rice-fish-culturue system,extensive and semi-intensive culture systems had obvious spatio-temporal emission characteristics.Taking Qinling Mountains and Huaihe River as the boundary,there were north-south differences in greenhouse gas emissions in those systems,and there was high spatial variability within each aquaculture water area.The temporal emission characteristics were mainly affected by temperature,and the emission flux of CH4,CO2 and N2O wasgreater in the high temperature seasons like summer and autumn,and there wereobvious diurnal variations.The order of N2O emission was intensive(yield coefficient 26.10 g·kg-1,area coefficient 157.67 g·m-2)>rice-fish culture system(4.11 g·kg-1,0.40 g·m-2)>extensive and semi-intensive culture system(0.43 g·kg-1,0.19 g·m-2).The highest emission of CH4 was found in the extensive culture system(189.02 g·kg-1,76.37 g·m-2),and the highest emission of CO2 was found in the rice-fish culture system(3 357.24 g·kg-1,1 079.36 g·m-2).[Conclusion]Freshwater culture system in our country is the source of greenhouse gases,with obvious spatial and temporal variation characteristics Accurately compiling greenhouse gas emission inventory of freshwater culture system will be an important part of realizing"carbon peak and carbon neutrality"of agriculture.
[Objective]Review the mechanism of food-induced enteritis caused by plant protein,and the repair effect of prebiotic,probiotics,and functional amino acids on food induced enteritis,in order to provide a reference for the repair of food-induced enteritis in fish.[Method]Taking the anti-nutritional factors contained in plant protein as the starting point,the effects of plant protein sources on fish intestinal mechanical barriers,chemical barriers,biological barriers and immune barriers were respectively explained.The positive effect of functional feed additiveson repair of food-induced fish enteritis were explained from the three different perspectives of prebiotics(oligosaccharides,polysaccharides,acidic agents,etc.),probiotics and functional amino acids,respectively.[Result and Conclusion]Anti-nutritional factors contained in plant proteins can cause damage to intestinal barrier of fish.Functional feed additives such as prebiotics,probiotics,and functional amino acids can alleviate food-induced enteritis.They can maintain fish intestinal health through competitive inhibitory proliferation of pathogenic bacteria,repairing intestinal mucosa structure,reducing inflammatory response and oxidation stress.
[Objective]To effectively remove the fishy substances from golden pomfret(Trachinotus ovatus)during processing,the process for removing the fishy substances from golden pomfret was optimized and the changes in flavour compounds before and after deodorisation were analyzed.[Methods]A one-way and response surface test using fishy smell value and sensory score as indicators was conducted to optimize the formula of the deodorant mixture of perilla extract,patchouli extract and yeast extract.The changes in volatile flavour substances and trimethylamine content before and after deodorization were compared and analyzed by using an electronic nose and gas chromatography-ion mobility spectrometry(GC-IMS)combined with relative odour activity value of flavour substances.[Result]The best deodorization and organoleptic evaluation effects of golden pomfret was achieved when the added patchouli extract mass fraction was 0.20%,perilla extract mass fraction was 0.15%,yeast extract mass fraction was 0.12%,the material-liquid ratio was 1:3 g/mL,and when it was soaked for 40 min at 4℃.The relative content of aldehydes was reduced by 29.80%,and the mass fraction of trimethylamine was reduced by 42.68%after being soaked in the mixed deodorising solution.[Conclusion]The mixed deodorizing solution of perilla extract,patchouli extract and yeast extract could effectively remove the fishy smellof Trachinotus ovatus beingprocessed.
