饥饿及恢复生长对方斑东风螺抗氧化体系的影响

在(25.8±1.7)℃条件下,测定了方斑东风螺(Babylonia areolata)不同饥饿期(7d、15d、25d、40d)后再投喂(30d)过程中足肌、肝胰脏的抗氧化体系相关指标变化。结果显示,分别饥饿25d和40d时幼螺两组织丙二醛(MDA)含量较对照组均显著升高;饥饿25d前,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)活力较对照组逐渐增强,当禁食达40d时却显著减弱;谷胱甘肽硫转移酶(GST)活力饥饿状态下先略上升后下降,肝胰脏、足肌中分别于饥饿25d和40d时显著降低;谷胱甘肽还原酶(GR)活力及谷胱甘肽(GSH)含量随禁食延长均呈下降趋势。恢复生长后,除饥饿40d组GR活力及肝胰脏MDA水平较对照呈差异显著外,该组其余指标及其他各处理组相应指标均恢复至或接近对照组水平。结果表明,饥饿胁迫下螺体抗氧化体系虽被激活,但仍处于一定的氧化应激状态,提示幼螺养成中禁食时间不宜超过25d,且SOD、CAT与GPx活性可作为螺体饥饿胁迫状态的指示参数。     

Nutritional history does not modulate hepatic oxidative status of European sea bass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>) submitted to handling stress

The aim of the present study was to assess the impact of an acute handling stress on hepatic oxidative status of European sea bass (Dicentrarchus labrax) juveniles fed diets differing in lipid so urce and carbohydrate content. For that purpose, four diets were formulated with fish oil (FO) and vegetable oils (VO) as lipid source and with 20 or 0% gelatinized starch as carbohydrate source. Triplicate groups of fish with 74 g were fed each diet during 13 weeks and then subjected to an acute handling stress. Stress exposure decreased hematocrit (Ht) and hemoglobin (Hb) levels. Independent of dietary treatment, stress exposure increased hepatic lipid peroxidation (LPO). Stressed fish exhibited lower glucose 6-phosphate dehydrogenase (G6PD), catalase (CAT), and superoxide dismutase (SOD) activities, independent of previous nutritional history. In the VO groups, stress exposure increased glutathione peroxidase (GPX) activity. Diet composition had no effect on Ht and Hb levels. In contrast, dietary carbohydrate decreased hepatic LPO and CAT activity and increased glutathione reductase (GR) and G6PD activities. Dietary lipids had no effect on LPO. Fish fed the VO diets exhibited higher G6PD activity than fish fed the FO diets. In conclusion, dietary carbohydrates contributed to the reduction of oxidative stress in fish. However, under the imposed handling stress conditions, liver enzymatic antioxidant mechanisms were not enhanced, which may explain the overall increased oxidative stress.     

Influence of dietary zinc on lipid peroxidation,protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to study the effects of dietary zinc on lipid peroxidation, protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian) by feeding fish with increasing levels of zinc (15.3, 26.9, 40.8, 58.2, 68.9 and 92.5 mg Zn kg^?1) for 6 weeks. Results indicated that malondialdehyde (MDA) content and protein carbonyls (PC) in serum were the highest in fish fed diet containing 15.3 mg zinc kg^?1 diet (P < 0.05). Serum antisuperoxide anion (ASA), superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), glutathione reductase (GR) activities and glutathione (GSH) content were improved with increasing dietary zinc levels up to 40.8 mg zinc kg^?1 diet (P < 0.05) and levelled off (P > 0.05). Serum antihydroxy radical (AHR), catalase (CAT) and glutathione‐S‐transferase (GST) activities followed the similar pattern to that observed in ASA. The MDA and PC levels, ASA, AHR, SOD, CAT, GPx, GR, GST activities and GSH content in intestine, hepatosomatic and muscle tissue followed the similar pattern to that observed in serum. The present results indicated that zinc decreased lipid peroxidation and protein oxidation and improved antioxidant defence in fish.     

Assessment of tissue-specific effect of cadmium on antioxidant defense system and lipid peroxidation in freshwater murrel, Channa punctatus

The effects of different concentrations of cadmium chloride on the extent of lipid peroxidation (LPO) and alterations in the antioxidant enzyme activities were studied in liver, kidney and gill tissues of freshwater murrel, Channa punctatus. The fish specimens were exposed to 6.7, 13.4 and 20.1 mg l⁻¹ sublethal concentrations of cadmium chloride and the oxidative stress was assessed after 24, 48, 72 and 96 h post-exposure. The biomarkers selected for the study were thiobarbituric acid reactive substances for assessing the extent of lipid peroxidation and antioxidant defense system such as reduced glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GP_X), glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) activities. In general, the cadmium exposure elevated the LPO in subject tissues of treated group and modulated the activities of GPx, GST, SOD, CAT, GR and level of GSH after given exposure as compared to the control. All enzymes activities, except CAT (in kidney and gills), and amount of LPO elevated significantly (P < 0.05) in treated group with respect to control in all tissues, while significant difference was not observed between the exposed concentrations and within exposure duration. The results indicated that increase in LPO level and the fluctuation in antioxidant defense system in fish could be due to cadmium-induced increase in the production of reactive oxygen species (ROS). The potential role of these parameters as biomarkers of heavy metal pollution in aquatic system is discussed.     

Effects of diludine supplementation on growth performance,liver antioxidant enzyme activities and muscular trace elements of rainbow trout (Oncorhynchus mykiss) juveniles at a low water temperature

Diludine is used as an effective agent reducing mutagenic effects of environmental pollutants, increasing productivity and protecting reproductive system of parental individuals and quality of their offspring. A 10‐week study was conducted to evaluate potential effects of diludine on rainbow trout (Oncorhynchus mykiss) juveniles growth performance, feed utilization, survival rate, liver antioxidant enzyme activities (superoxide dismutase, SOD, EC1.15.1.1 ; catalase, CAT, EC1.11.1.16 ; glutathione peroxidase, GPx, EC 1.11.1.9 ; glutathione reductase, GR, EC1.6.4.2 ; glucose‐6‐phosphate dehydrogenase, G6PD, EC1.1.1.49 and glutathione S‐transferase, GST, EC1.5.1.18 ), the levels of malondialdehyde (MDA) as a lipid peroxidation marker and muscular trace elements at a low water temperature (9 °C). Diludine was added at 0.2, 0.5 and 1 g kg^?1 to a fish meal–based control diet, and each diet was fed to triplicate groups of rainbow trout juveniles. After 10 weeks, there were no differences in survival rate between fish fed experimental diets (P > 0.05). It was observed that a significant improvability existed for both growth and feed utilization in fish fed diets supplemented with diludine (P < 0.05). Antioxidant enzymes showed significantly increased activity in liver tissues (P < 0.05) and then a decrease to initial activity levels during the experimental time. (GPx activity was not determined in the juvenile livers.) SOD and GST activities in liver of fish fed the diets with diludine tended to be higher and GR activity tended to be lower than that in fish fed the basal diet. However, in general, it was determined that different concentration of diludine did not affect the studied antioxidant enzyme activities except G6PD in the liver of juveniles fed the diet with 1 g kg^?1 diludine. On the other hand, the significant reduction was found in MDA levels in the fish fed the diets with diludine compared with basal diet on the 14th and 28th days of experiment. It was also observed that Cu, Fe, Mg, Zn and Se levels were significantly higher in the juveniles fed the diet with 1 g kg^?1 diludine than those fed the basal diet. In conclusion, the results of this trial indicate that 1 g kg^?1 dietary supplementation with diludine seems to be most positive for rainbow trout production in cold‐water adaptation.     

Tissue-specific daily variation in the oxidative status of sturgeon (<Emphasis Type="Italic">Acipenser naccarii</Emphasis>) and rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>): a comparative study

The oxidative status is associated with animal lifespan, metabolism, activity and circadian rhythms. The objective of this work is to study the time course of the oxidative status over a daily cycle in the plasma, liver and brain, and the changes in the plasma cortisol levels of sturgeon and trout. The knowledge of daily oxidative status will provide a better understanding of the trout and sturgeon physiology and adequate maintenance and food supply of farmed fish in relation to photoperiod. Superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase activities, lipid peroxidation and cortisol were measured. Our results showed that the antioxidative enzyme activities and lipid peroxidation in the liver of trout and sturgeon changed through the day, with increased levels in lipid peroxidation of liver in the dark period for sturgeon. This could be related to the different activity time in both species, an issue to be taken into account when designing the guidelines of the maintenance of these species in fish farms. On the contrary, there was not clear influence of the daily rhythms on brain oxidative status. The higher efficiency of the antioxidant defences in the brain of sturgeon, which displays less lipid peroxidation and higher antioxidative activity, could be related to its longer life expectancy. The absence of any apparent daily rhythm in the plasma cortisol levels in sturgeon could indicate a lower susceptibility to stress, and that mechanisms involved in cortisol secretion in chondrosteans could be different from that described for teleosteans.     

Anti-oxidant status in embryonic,post-hatch and larval stages of Asian seabass (<Emphasis Type="Italic">Lates calcarifer</Emphasis>)

The concentrations of anti-oxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and selenium-dependent glutathione peroxidase (SeGPx), and low molecular weight free-radical scavengers such as reduced glutathione (GSH) and ascorbic acid (vitamin C) were evaluated during the period from gastrulation (GS) to 25 days post-hatch (dph) in the larvae of Asian Seabass, Lates calcarifer. Oxidative damage due to lipid peroxidation (LPO) was also assessed, by evaluation of the formation of malondialdehyde (MDA). All the three anti-oxidant enzymes, SOD, CAT and GPx, showed high activities during gastrulation, suggesting an increased metabolic rate during the period of embryonic development. Though the SOD activity apparently decreased progressively during 3–20 dph of larval development, the difference was not significant. CAT showed high activity during gastrulation and remained constant up to 3 dph, suggesting an increased need to metabolise hydrogen peroxide (H₂O₂) and organic peroxides. In contrast, SeGPx activity increased progressively from 5 dph to 25 dph during larval development, indicating an increased need to detoxify lipid peroxides. This is evident from the observation of increased lipid peroxidation from 10 dph to 25 dph during larval development. GSH levels were low at gastrulation, indicating increased metabolic rate and formation of lipid radicals during this period, corresponding to the decrease in the level of ascorbic acid, which is consumed for regeneration of GSH.     

Antioxidant processes are affected in juvenile rainbow trout (Oncorhynchus mykiss) exposed to ozone and oxygen-supersaturated water

Two groups of juvenile rainbow trout (Oncorhynchus mykiss) were exposed for 4 h to either hyperoxic (>40 mg O₂/l) or ozonised (5.2 μg O₃/l) water containing supersaturated oxygen. Gill, liver, blood cells and plasma were taken 1, 5, 12, 24 and 48 h following the exposure periods and antioxidant responses and oxidative damage studied in terms of, respectively, antioxidant enzyme activities/glutathione status and lipid peroxidation. Observed biochemical changes were significant at p<0.05. Ozonation elevated oxidised glutathione (GSSG) levels, increased lipid peroxidation and decreased reduced glutathione (GSH) levels in gills 1 h following exposure, which indicate oxidative stress. However, the longer-term effects (48 h) following ozone exposure resulted in increased GSH levels in both gills and liver and, measured as oxidative stress index (OSI), were indicative of enhanced potential of tissues to resist oxidative stress. Ozonation also resulted in elevated activity of superoxide dismutase (SOD) at 5–12 h following exposure in gills compared to 24–48 h in liver, indicating either differential regulation and time-courses of response, or an earlier impact of ozonolysis products on gills than liver. In contrast, catalase activity was elevated in both gills and liver at 24 h by the effects of hyperoxia alone. Hyperoxia also decreased GSSG levels in both gills and liver, but had no effect on lipid peroxidation. Increases were seen in the activities of selenium-dependent glutathione peroxidase as a result of ozonation (gills; 5 and 24 h) and hyperoxia (liver; 1 h), and in total GPX (Se-dependent and independent) as a result of ozonation (both tissues; 48 h), but no effects were seen on glutathione reductase (GR) in either tissues. Levels of GSH were increased in blood cells at various times following hyperoxia. Overall, the results show (i) differential antioxidant and pro-oxidant effects of ozonation compared to hyperoxia, (ii) gills and possibly blood as the first line of impact and defence, with later effects on liver, and (iii) that even after 24–48 h following ozone exposure, all antioxidant defences had not returned to pre-exposure values.     

Study of the Oxidative State,as a Marker of Welfare,on Gilthead Sea Bream,Sparus aurata,Subjected to Handling Stress

In this study, we investigated the effect of repeated handling on the oxidative state of gilthead sea bream, Sparus aurata. We determined the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione transferase (GST), and DT‐diaphorase (DTD) in liver, digestive tract, brain, gills, and white muscle. We also measured the lipid‐peroxidation level (malondialdehyde – MDA – concentration) and the glucose 6‐phosphate dehydrogenase activity (G6PDH). The results show that repeated low‐intensity handling on gilthead sea bream alter the oxidative status of tissues such as liver, digestive tract, and muscle in the last term can affect its welfare. The brain in a situation of handling stress is protected from oxidative damage by the activity of antioxidant enzymes. Finally, the concentration of MDA in tissues can be a good candidate as a biomarker of stress and welfare in fish.     

Methionine hydroxy analogue prevents oxidative damage and improves antioxidant status of intestine and hepatopancreas for juvenile Jian carp (Cyprinus carpio var. Jian)

Oxidative damage and antioxidant status of intestine and hepatopancreas for juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of methionine hydroxy analogue (MHA: 0, 5.1, 7.6, 10.2, 12.7, 15.3 g kg^?1 diet) for 60 days were studied. Radical scavenging ability, antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT), glutathione‐S‐transferase (GST), glutathione peroxidase (GPX) and glutathione reducase (GR), as well as glutathione (GSH), protein carbonyl (PC) and malondialdehyde (MDA) contents were assayed in these tissues. Results indicated that anti‐superoxide anion capacity in intestine and anti‐hydroxyl radical capacity in hepatopancreas significantly improved with dietary MHA levels up to 7.6 and 10.2 g kg^?1 diet respectively, whereupon they decreased (P < 0.05). SOD, CAT, GST, GPX, GR activities in intestine and hepatopancreas, as well as GSH content in hepatopancreas significantly increased with optimal MHA levels which were in the range of 5.1–10.2 g kg^?1 diet, and thereafter decreased (P < 0.05). Meanwhile, MDA and PC contents in these tissues together with GOT and GPT activities in plasma significantly decreased with optimal MHA levels which were in the range of 5.1–7.6 g kg^?1 diet, and thereafter increased (P < 0.05). These results suggested that MHA improved antioxidant status and depressed lipid and protein oxidation in intestine and hepatopancreas.     

Effects of dietary histidine on antioxidant capacity in juvenile Jian carp (Cyprinus carpio var. Jian)

In the present study, we tested the hypothesis that dietary histidine could improve antioxidant capacity of juvenile Jian carp (Cyprinus carpio var. Jian). A total of 1,200 juvenile Jian carp were fed graded levels of histidine at 2.3 (unsupplemented control), 4.4, 6.3, 8.6, 10.8 and 12.7 g/kg diet for 60 days. Results showed that the content of malondialdehyde (MDA) and protein carbonyl (PC) in serum and all tissues apparently decreased with increasing histidine levels up to an optimal level and increased thereafter. Anti-superoxide anion (ASA) capacity, glutathione peroxidase (GPX) activities and glutathione (GSH) content in serum and all tissues, anti-hydroxyl radical (a-HR) capacity, catalase (CAT) and glutathione-S-transferase (GST) activities in serum, muscle and intestine, superoxide dismutase (SOD) activities in serum and intestine, as well as glutathione reductase (GR) activity in serum, muscle and hepatopancreas were improved by dietary histidine. Fish fed diet with 8.6 g/kg histidine had lower serum glutamate-pyruvate transaminase (GPT) activity than that fed with control diet, whereas pattern of glutamate–oxaloacetate transaminase (GOT) activity was opposite. The present results suggested that histidine could improve antioxidant capacity and inhibit lipid peroxidation and protein oxidation of juvenile Jian carp.     

Effects of fish size on the response of antioxidant systems of Oreochromis niloticus following metal exposures

The size of a fish is an important factor in its physiology, and metal uptake is affected by animal physiology. In this study, small and large tilapias (Oreochromis niloticus) differing approximately twofold in length and fivefold in weight were compared for their antioxidant response. Both groups were exposed to Cu or Cr (1.0 μg/mL) in a freshwater (?80 mg CaCO₃/L, conductivity 1.77 mS/cm) using 2 exposure protocols (20 μM for 48 h and 10 μM for 6 days). Following the exposures, the antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX; glutathione reductase, GR and glutathione S-transferase, GST) and glutathione (GSH) levels were measured in the liver of fish. Results showed that small fish was affected from exposure conditions much more than large ones as their antioxidant parameters significantly decreased even in controls. Metal exposures of small fish caused significant increases in SOD and CAT activity in acute Cu or Cr exposures. Subchronic Cr exposure of small fish also caused significant increases in CAT, GPx and GST activities, while there was no significant change in Cu-exposed ones. Large fish, however, showed different antioxidant responses as their levels mostly decreased. This study demonstrated that the response of antioxidant system in the liver of tilapia varied in relation to fish sizes and emphasized using different size groups in environmental monitoring and also in evaluation of fish biomarkers.     

Dietary lycopene supplementation on Nile Tilapia (Oreochromis niloticus) juveniles submitted to confinement: effects on cortisol level and antioxidant response

This study evaluates the inclusion of lycopene in the commercial diet for Nile Tilapia exposured to a stressor. For 60 days, fish diet was supplemented with lycopene (600 mg kg^?1 diet) and at the end, subjected to confinement for 90 min. Zootechnical parameters (weight gain, specific growth rate and intake), hormonal (cortisol level), biochemical {enzyme activity and lipid peroxidation level [thiobarbituric acid (TBARS)]} and physical (instrumental colour) parameters were also evaluated. Supplementation with lycopene did not alter zootechnical parameters. In unconfined fish, catalase (CAT) activity was reduced in the white muscle of fish fed with lycopene; however, in red muscle, it was not altered. In fish under confinement, plasma cortisol increased as well as CAT, glutathione reductase (GR) and lactate dehydrogenase (LDH) activity in both muscles. Lipid peroxidation of the fillet also displayed higher values. However, the lycopene supplementation abolished the effects of confinement available through cortisol levels, remaining unchanged in the above parameters, activity of CAT, GR and LDH in both muscles and TBARS content of the fillet; in addition, it did not induce alteration of fillet coloration. Inclusion of lycopene in commercial feed reduces the impact of confinement and does not alter the zootechnical parameters; additionally, no modification of the fillet colour from juvenile Nile tilapia was observed.     

饥饿及恢复投饵过程中花鲈肌肉组成及非特异免疫水平的变化

探讨了饥饿及恢复投饵过程中花鲈（Lateolabrax japonicus）（196±38g）肌肉组成分及鱼体非特异免疫水平的变化。实验设S0组（对照组,持续正常投喂）,S5组（饥饿5d后恢复正常投喂）,S10组（饥饿10d后恢复正常投喂）,S15组（饥饿15d后恢复正常投喂）。S0组每隔5d取样,S5,S10和S15组分别在结束饥饿及恢复投饵后每隔5d取样测定。结果显示：饥饿程度对花鲈肌肉组成有显著影响。与对照组相比,S10组饥饿结束时肌肉的总脂含量显著降低;S15组饥饿结束时肌肉的总脂含量和粗蛋白含量都显著降,同时显著增加了肌肉的水分含量。表明饥饿过程中花鲈先动用肌肉脂肪,后动用肌肉蛋白。在恢复投饵过程中,S10和S15组总脂含量表现出先降后升的规律,而S15组蛋白表现为逐步回升的趋势。表明花鲈在饥饿后恢复投饵的过程中,先恢复肌肉蛋白含量,后恢复肌肉脂肪含量。饥饿15d时花鲈血清蛋白浓度显著降低。与对照组相比,S5组血清、脾脏和头肾溶菌酶活性均无显著变化;S10组头肾溶菌酶活性在恢复投饵10d时补偿性升高。S15组在饥饿结束时显著降低了花鲈头肾溶菌酶活性,但在恢复投饵5d时恢复到对照组水平。花鲈白细胞的吞噬活性也受饥饿程度及恢复投饵的影响。饥饿会降低花鲈血液白细胞的吞噬活性。在恢复投饵过程中,饥饿（5d）后恢复投饵会引起白细胞吞噬百分率和吞噬指数的补偿性升高。表明饥饿及恢复投饵也影响花鲈的非特异免疫水平。     

胆碱对高脂胁迫的团头鲂肝脏抗氧化、组织结构和免疫力的影响

以初始体质量(42.20±0.34)g团头鲂为研究对象,研究饲料中添加胆碱对高脂胁迫团头鲂肝脏抗氧化、组织结构和免疫力的影响。实验采用2×2因子设计方法,共配置2个脂肪水平(5%和15%)和2个胆碱水平(1200和2200 mg/kg)的等氮饲料4组。养殖实验在室内循环水系统中进行,养殖周期为8周。养殖实验结束后进行血液和肝脏生化指标、肝脏抗氧化指标和非特异性免疫指标等的检测分析,以及观察肝细胞的超微结构变化。结果显示,当饲料中添加1200 mg/kg胆碱时,随着脂肪水平的升高,团头鲂肝脏脂肪含量和甘油三酯浓度显著增加,而血浆中谷草转氨酶(AST)和谷丙转氨酶(ALT)活性则显著上升;肝脏中丙二醛(MDA)含量、总超氧化物歧化酶(t-SOD)活性、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)活性等显著升高;血液中白细胞数、溶菌酶活性、总蛋白和球蛋白水平以及还原型谷胱甘肽(GSH)活性显著降低;超微结构观察到肝细胞中存在大量脂滴,伴随着细胞核变性、核膜残缺、线粒体水肿等异常现象。这些结果表明高脂日粮不仅导致肝细胞的结构和功能的损伤,而且造成肝脏氧化应激和机体免疫力的下降。在高脂饲料(15%脂肪)中添加2200 mg/kg胆碱,可显著降低肝脏脂肪含量、血浆谷草转氨酶(AST)和谷丙转氨酶(ALT)活性,显著降低肝脏丙二醛(MDA)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,并显著提高白细胞数和球蛋白水平以及还原型谷胱甘肽(GSH)活性,同时肝细胞形态及细胞器结构也趋于正常。研究表明,添加适量胆碱能够减少肝脏脂肪沉积,维持肝脏结构和功能的正常,并增强团头鲂抗氧化能力和机体免疫力,继而保持鱼体的健康。     

不同温度下BDE-209对草鱼离体肝脏组织的毒性效应

为探讨不同温度条件下十溴联苯醚(BDE-209)对鱼类的毒性影响,以草鱼(Ctenopharyngodon idellus)幼鱼离体肝脏组织为试验材料,在肝脏组织匀浆液中加入浓度为0.00、0.04、4.00、400.00μg/L的BDE-209,并将其分别置于低温(15℃)、常温(25℃)、高温(35℃)中水浴60 min,然后检测肝脏组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)的活性以及丙二醛(MDA)的含量。结果显示:低温时各浓度组BDE-209诱导下的SOD、CAT、GR活性与对照组没有显著性差异;常温时BDE-209对SOD、CAT、GR活性具有低浓度诱导高浓度抑制的现象,高温时BDE-209对肝脏组织中CAT、SOD、GR活性造成明显的抑制效应,MDA在不同温度条件下其含量都随BDE-209暴露浓度的升高而升高。研究结果表明:在一定的温度范围内,温度越高,BDE-209对鱼体肝脏组织造成的氧化损伤越大。     

Effect of diet composition on growth performance,hepatic metabolism and antioxidant activities in Siberian sturgeon (<Emphasis Type="Italic">Acipenser</Emphasis><Emphasis Type="Italic">baerii</Emphasis>, Brandt, 1869) submitted to starvation and refeeding

Many fish species undergo natural starvation periods. Adaptation to starvation is possible through the activation of behavioral, biochemical and physiological mechanisms. Knowledge of the effect of dietary nutrients on the intermediary metabolism during starvation and refeeding can be useful to improve fish health and optimize aquaculture production. To analyze the effect of dietary nutrients on liver metabolism of Siberian sturgeon (Acipenser baerii) submitted to starvation and refeeding, four isoenergetic diets differing in nutrient composition were designed: LP-St (38 % protein, 12 % lipid, 36 % carbohydrate), HP-St (44 % protein, 10 % lipid, 30 % carbohydrate), LP-L (38 % protein, 18 % lipid, 25 % carbohydrate) and HP-L (44 % protein, 16 % lipid, 22 % carbohydrate). Four groups of fish were fed 3 weeks to satiety with the corresponding diet, starved for 2 weeks and then refeed 5 weeks to satiety on the same diet. Starvation mobilized the hepatic lipid store to a greater extent than glycogen. Starvation increased superoxide dismutase activity irrespective of the diet, while low protein diets (LP-St and LP-L) increased catalase activity. The oxidative damage decreased after 5 weeks of refeeding. Refeeding the starved fish on the HP-St diet promoted the greatest growth performance. In addition to reporting for the first time the effect of diet composition on growth, liver composition and antioxidant activities in Siberian sturgeon submitted to starvation and refeeding, our findings suggest that refeeding on HP-St diet stimulated the use of dietary carbohydrates and allowed a protein sparing effect in Siberian sturgeon.     

Effects of a dietary administration of purple coneflower (Echinacea purpurea) on growth,antioxidant activities and 8 miRNAs expressions in crucian carp (Carassius auratus)

Echinacea purpurea (EP), a globally popular herbal medicine, has been used to treat various diseases in human and animals. However, little has been reported about its effects in fish. In this study, crucian carp (Carassius auratus) were selected to evaluate the effects of EP on growth performance and antioxidant response and the expressions of microRNAs. The results showed EP could stimulate the growth of crucian carp with the best effect was observed at dose of 4 g kg^?1. In serum, the content of hydroxyl radical (·OH) and malondialdehyde (MDA) decreased by EP supplementation, whereas the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) increased. Similarly, the content of ·OH decreased, and the activities of CAT, GPX and GR increased in liver of crucian carp. Furthermore, in livers of crucian carp, EP supplements upregulated the expressions of the microRNAs (miR‐16, miR‐21, miR‐125b, miR‐146a, miR‐155, miR‐181a and miR‐223), which had been confirmed to participate in regulating antioxidant and immune function in mammals. Our results suggest EP supplements in diets stimulated growth performance and antioxidant response of crucian carp. In liver, the upregulation of specific miRNAs may participate in the antioxidant effects of EP diets.     

Beneficial effects of thyme (Thymus vulgaris) extract on oxytetracycline‐induced stress response,immunosuppression, oxidative stress and enzymatic changes in rainbow trout (Oncorhynchus mykiss)

The aim of the present study was to investigate the effects of thyme extract (TE) and oxytetracycline (OTC) on rainbow trout (Oncorhynchus mykiss) stress response, immune parameters, oxidative stress and enzymatic changes. The fish were assigned into eight treatments receiving diets with OTC (0 and 2.5 g/kg) and TE (0, 5, 10 and 20 g/kg) for 2 weeks. Thereafter, serum characteristics and gut oxidative status were evaluated. OTC significantly increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, and cortisol and glucose levels; however, TE significantly suppressed these changes. OTC significantly decreased, but TE significantly increased gut catalase (CAT) and glutathione peroxidase (GPx) activities. OTC significantly decreased gut superoxide dismutase (SOD) and increased gut glutathione‐s‐transferase (GST) activities, malondialdehyde (MDA) content and blood monocyte percentage; TE significantly mitigated these changes. TE significantly increased serum total protein, total Ig, lysozyme and ACH50, and blood WBC; however, OTC significantly decreased serum lysozyme and ACH50 activities and blood WBC and neutrophil percentage. In conclusion, OTC administration causes immunosuppression, which might be related to deterioration of fish health. TE augments trout innate immune and antioxidant status and is capable to counteract OTC‐induced health and immune deterioration.