Response of enzyme activities and metabolic intermediate concentrations to a long burst of exercise and following resting in muscle and the hepatopancreas of carp

ABSTRACT: The responses of enzyme activities and metabolic intermediate concentrations to a long burst of exercise and following resting were examined in muscle and the hepatopancreas of carp Cyprinus carpio . A 15 min burst of exercise made the fish so exhausted that they could not swim any more. In muscle, the exercise decreased glycogen content significantly and increased lactate content significantly, resulting in a lowered pH. Furthermore, the burst of exercise decreased phosphofructokinase (PFK) activity significantly, although it changed adenosine-5'-monophosphate, adenosine-5'-diphosphate, adenosine-5'-triphosphate, fructose-6-phosphate and citrate concentrations within ranges that could activate PFK. In the hepatopancreas, the exercise increased glucose-6-phosphatase and fructose-1,6-bis-phosphatase activities, and glucose and lactate concentrations in the serum, and it decreased glycogen content. Even at 3 h resting after the burst of exercise, the fish had not completely restored many parameters. These results suggest that although the fish tried to enhance in vivo muscular glycolysis through the activation of PFK by changes in metabolic intermediate concentrations, glycolysis seemed to decrease markedly through the inhibition of PFK as a result of the lowered pH. However, the hepatopancreas made a contribution to muscular exercise through glucose supplementation by enhanced gluconeogenesis and glycogenolysis, indicating the presence of an interdependence of carbohydrate metabolism between muscle and the hepatopancreas in the fish.     

注射葡萄糖对吉富罗非鱼血浆生化指标、胰岛素和糖酵解关键酶的影响

研究注射葡萄糖对吉富罗非鱼(Oreochromis miloticus)生化指标、胰岛素和糖酵解酶的影响。选取体质量约80 g的吉富罗非鱼150尾,随机分为2个实验组,对照组腹腔注射0.7%的无菌生理盐水,处理组按照30 mg/100 g(体质量)的剂量腹腔注射葡萄糖。结果表明:(1)吉富罗非鱼在注射葡萄糖后1 h血糖达到最高水平,而后显著下降(P<0.05),3 h后降低到正常水平。注射葡萄糖可显著提高胆固醇的含量(P<0.05),并显著降低谷草转氨酶水平(P<0.05),但对血浆蛋白、甘油三酯和谷丙转氨酶水平没有显著影响(P>0.05)。(2)肝糖原在葡萄糖注射后的6 h达到最高水平,而后显著下降(P<0.05),肌糖原没有发生变化。(3)血浆和肌肉中的胰岛素均在葡萄糖注射后的3 h达到最高水平,而后显著下降(P<0.05),而肝中的胰岛素水平没有发生变化。(4)丙酮酸激酶的活力在葡萄糖注射后6h达到最高水平(P<0.05),己糖激酶的活力在注射葡萄糖后没有发生变化。结果表明,注射葡萄糖可显著提高吉富罗非鱼血糖水平,且维持时间较长,胰岛素含量和丙酮酸激酶(PK)活力的提高均相对延迟,而己糖激酶活力的不足又限制了葡萄糖的酵解反应,从而引起血浆胆固醇升高,并伴有持续的血糖和肝糖原升高,从而产生营养胁迫的生理反应,加重鱼类对葡萄糖的代谢负担。     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

饥饿及再投喂处理对草鱼生长、葡萄糖代谢和转运蛋白1表达的影响

设置持续投喂组(C,持续投喂8周)、饥饿再投喂组(R,饥饿4周+再投喂4周)和持续饥饿组(S,饥饿8周)3个处理组,研究3种不同饥饿处理对草鱼(Ctenopharyngodon idellus)血清生化指标、糖原和糖代谢相关酶和葡萄糖转运蛋白1(GLUT1)的影响,同时在此实验基础上研究草鱼在急性高糖负荷胁迫下的糖耐受能力、糖代谢相关酶和GLUT1的变化规律,旨在阐明草鱼在饥饿及再投喂处理条件下的糖代谢特征。选取初重为(125.35±0.54)g的草鱼,饲养8周后以30 mg/100 g体重的剂量腹腔注射葡萄糖研究其糖耐受能力。结果显示,S组肝糖原和血清的血糖、甘油三酯含量均最低。饥饿处理对草鱼糖耐受能力影响显著,S组血糖含量在各时间点上显著低于其余两组(P0.05),肝糖原在6 h达到峰值;饥饿处理对草鱼肝脏糖代谢关键酶影响显著,饥饿处理(S组)诱使磷酸烯醇式丙酮酸激酶(PEPCK)活性上升但抑制丙酮酸激酶(PK)和果糖-6-磷酸激酶(PFK)的活性(P0.05),而饥饿再投喂(R组)后PEPCK、PK和PFK酶活性恢复到持续投喂(C组)处理水平。注射葡萄糖后S组肝脏GK酶活性增幅最大,PK酶活性呈上升趋势,而R组则呈先下降后上升的趋势;饥饿处理对草鱼肝脏和肌肉GLUT1表达影响显著,注射葡萄糖后,除R组肝脏组织外,其余各组草鱼肝脏和肌肉组织GLUT1表达量均呈先上升后下降的趋势,且S组肌肉GLUT1表达量在各个时间点上均高于其余两组(P0.05)。研究结果表明,在不同饥饿处理下,草鱼可通过消耗肝糖原和甘油三酯及降低肝脏糖酵解相关酶(PK和PFK)活性和促进糖异生PEPCK酶活性来应对饥饿胁迫,而饥饿处理可诱使GK和PK酶活性上升、促进糖原合成和激活GLUT1基因的表达和转运来缓解草鱼急性高糖负荷,从而提高其糖耐受能力。     

异育银卿口服葡萄糖后血糖、血脂和肝糖原的变化

禁食 4周后对体重为 46± 5g的异育银鲫进行了葡萄糖耐量试验。口服 16 7mg·(10 0g) -1体重的葡萄糖之前及之后的 1、2、3、4、5、6、8、10、14、18和 2 4h分别抽血、取肝胰腺 ,分析血糖、血脂和肝糖原含量。实验结果表明 ,血糖在口服葡萄糖后 3h内迅速升高 ,并于 3h时达最高水平 ,以后逐渐下降。口服葡萄糖后 1h血脂含量最高 ,然后开始下降 ,并于 8h时又开始升高。口服葡萄糖后的最初 2h内肝糖原含量显著降低 ,随后开始提高 ,并在 6h时达最高峰。用体重为 (16 4± 12 )g的异育银鲫为材料禁食 4周后灌喂不同剂量的葡萄糖 ,研究葡萄糖剂量对血糖和肝糖原变化规律的影响。结果表明 ,随着口服葡萄糖剂量的增加 ,血糖升高幅度加大 ,而肝糖原含量则随葡萄糖剂量增加而减少。上述实验结果提示异育银鲫在胰岛素的分泌方面与哺乳类存在本质的不同。     

草鱼、银鲫和青鱼捕捞后的应激反应

分别评价了捕捞对草食性(草鱼)、杂食性(银鲫)和肉食性(青鱼)鲤科鱼类血液指标(血浆史质醇、葡萄糖和乳酸浓度)、肝糖原含量和两种肝脏糖酵解酶(己糖激酶和丙酮酸激酶)活性的影响。结果显示:草鱼、银鲫和青鱼捕捞后血浆史质醇、葡萄糖和乳酸浓度均显著升高;草鱼和青鱼捕捞后2 h时肝糖原含量呈下降趋势,但银鲫捕捞前、后肝糖原含量未出现显著变化;捕捞前、后青鱼血糖浓度显著高于草鱼和银鲫。银鲫肝糖原含量显著高于草鱼和青鱼,其捕捞后血浆葡萄糖和乳酸浓度增加幅度较小,这意味着捕捞后银鲫应激反应强度相对较低。草鱼和银鲫捕捞后肝脏己糖激酶和丙酮酸激酶活性未发生显著变化,青鱼捕捞后2 h己糖激酶活性显著下降,这意味着捕捞应激后血糖升高未导致草鱼、银鲫和青鱼的肝脏糖酵解酶活性增强。     

土霉素在锯缘青蟹体内的药物代谢和消除规律

采用高效液相色谱法检测土霉素,研究土霉素口灌给药途径下在锯缘青蟹体内的药代动力学。锯缘青蟹口灌给药土霉素50 mg/kg后,其血浆、肌肉和肝胰脏中的药峰浓度分别为16.78±1.98 mg/L、9.39±2.12μg/g和32.12±6.12μg/g,达峰时间分别为4 h、8 h和4 h。血浆中土霉素浓度-时间关系曲线符合一级吸收的二室开放动力学模型。土霉素在锯缘青蟹体内分布广泛,其表观分布容积(Vd)为2.129 L/kg;分布半衰期(t1/2α)和消除半衰期(t1/2β)分别为3.200 h和47.856 h,总体清除率(CLs)为0.063 mL/(kg.h)。肌肉和肝胰脏中土霉素浓度与时间关系的药动学参数采用统计矩原理分析,其消除半衰期(t1/2 z)分别为60.145 h和71.009 h,总体清除率(CLz)分别为0.054 g/(kg.h)和0.037 g/(kg.h)。土霉素在精巢和卵巢中达峰时间分别为8 h和12 h,峰浓度分别为9.83μg/g和10.26μg/g。给药后24 d时,血浆、肌肉、肝胰脏、精巢和卵巢中土霉素含量都已低于0.10μg/g。土霉素在锯缘青蟹体内消除比较缓慢。     

低氧–复氧对脊尾白虾呼吸代谢和抗氧化酶活力的影响

以静室呼吸耗氧–复氧为实验组,持续充气组为对照组。于0、1、2、4、5 h及复氧1、4、8 h检测并分析了水体溶解氧(DO)和脊尾白虾(Exopalaemon carinicauda)组织主要呼吸代谢及抗氧化酶活力。结果显示,随着时间的延长,实验组DO不断降低,且显著低于对照组(P<0.05)。脊尾白虾鳃、肝胰腺和肌肉细胞色素C氧化酶(CCO)、琥珀酸脱氢酶(SDH)活力降低;乳酸脱氢酶(LDH)、延胡索酸还原酶(FRD)活力升高,SDH/FRD值降低。复氧后,3种组织SDH、LDH和FRD活力恢复至对照组,肌肉CCO活力升高,在复氧8 h时低于对照组(P<0.05);SDH/FRD值升高。随着时间的延长,3种组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽S转移酶(GST)活力均先升后降,但肝胰腺的过氧化物酶(POD)活力降低,而在鳃和肌肉中呈波动性变化;复氧后,3种组织SOD、CAT、GPX和GST活力均恢复至对照组水平,但鳃和肌肉的POD在复氧8 h时均低于对照组(P<0.05)。研究表明,随着DO的降低,脊尾白虾有氧代谢逐渐降低,无氧代谢逐渐升高。复氧后,有氧代谢能力又逐渐恢复。上述抗氧化酶可能在脊尾白虾应对低氧-复氧中产生的氧化损伤发挥着重要作用。     

船载振动胁迫对斑石鲷影响实验研究

为了探索鱼类在船载振动条件下的应激响应和适应性,为深远海大型养殖平台养殖工艺设计与模式构建提供基础数据和理论依据,利用机械振动台模拟船载工况,研究不同振动频率和时间条件下斑石鲷(Oplegnathus punctatus)的血液和生化指标变化情况。结果表明:振动时间5 min,10 Hz组和50 Hz组的斑石鲷各方面指标均与对照组无显著性差异,30 Hz组的血清葡萄糖显著降低,皮质醇和肾上腺素指标显著升高,肌糖原和肝糖原无显著差异;振动时间60 min,各实验组斑石鲷的血清葡萄糖指标均显著降低,皮质醇和肾上腺素指标显著升高,但对肌糖原和肝糖原指标无显著影响;水质变化情况显示,振动60 min后水体内溶氧浓度和氨氮浓度指标有所上升,水温、盐度、p H等无明显变化。研究表明,低频振动对鱼类的影响主要是通过产生水流变化进而被侧线器官感受到,引起斑石鲷脑神经兴奋,产生应激。短时振动对斑石鲷不会造成较大影响,而长时间振动会引起斑石鲷一定程度的应激反应。     

Pb~(2+)对建鲤幼鱼抗氧化酶活性和总抗氧化能力的影响

为了解铅对建鲤幼鱼(Cyprinus carpio var.Jian)的影响,将建鲤幼鱼暴露于不同水平(0、0.648、1.296、6.480 mg/L)的Pb2+水溶液中,于96 h分别测定建鲤幼鱼肝胰脏、肠、鳃、肌肉中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活性及总抗氧化能力(T-AOC)。结果表明:随着Pb2+浓度的升高,抗氧化酶活性升高,达到极值后下降。0.648 mg/L浓度组中,肝胰脏中抗氧化酶活性及总抗氧化能力均有较明显升高;肌肉中抗氧化酶活性及总抗氧化能力变化较小;在高浓度组(6.480 mg/L),肾中的三种抗氧化酶活性及总抗氧化能力仍在升高,而在其他组织中酶的活性有所降低。上述研究结果表明,与肠、鳃、肌肉、肾相比,肝胰脏中的抗氧化酶活性及总抗氧化能力敏感,是最先启用的主要解毒器官;在高浓度胁迫时,肝胰脏解毒能力下降,抗氧化防御作用的主要器官由肝胰脏转移到肾脏。     

溶藻弧菌对三疣梭子蟹溶菌酶和磷酸酶活性的影响

将健康的三疣梭子蟹（平均体重176±21.3g）分别注射生理盐水和溶藻弧菌,在感染后0、24、48和72h分别采集不同处理组梭子蟹的血淋巴、肌肉和肝胰腺组织,测定其中的溶菌酶（LSZ）、酸性磷酸酶（ACP）及碱性磷酸酶（ALP）活性,研究溶藻弧菌对三疣梭子蟹体内免疫相关酶活的影响。结果表明,感染组梭子蟹血淋巴LSZ活性在感染后24h显著高于对照组（P〈0.05）,随后活性显著降低（P〈0.05）;肌肉和肝胰腺组织中LSZ活性在感染24h有稍微上升的趋势,但是随着感染时间的延长其活性又逐渐下降,且在感染48h后分别显著低于对照组（P〈0.05）。感染组梭子蟹不同组织中ACP和ALP酶活随着感染时间的延长均呈下降的趋势,且感染48h后显著低于对照组（P〈0.05）。试验表明,三疣梭子蟹感染溶藻弧菌后对机体免疫相关酶活指标的影响较大,导致机体免疫防御能力的减弱。     

三种糖代谢调控剂对异育银鲫生长、血液生化指标和糖原代谢的影响

在高糖基础日粮中分别添加10 mg/kg罗格列酮、10 mg/kg格列本脲、4 g/kg 1,6-二磷酸果糖,饲喂初始重量为(4.87±0.12)g的异育银鲫(Carassius auratus gibelio),对照组喂基础日粮,饲喂56 d后测定了这三种糖代谢调控剂对异育银鲫生长、血液生化指标和糖原代谢的影响。结果表明:与对照组相比,饲料中添加罗格列酮后饵料系数显著降低(P<0.05),添加罗格列酮和格列本脲后,肝体比显著增大(P<0.01);与对照组相比,罗格列酮能提高血清总蛋白含量(P<0.05)、球蛋白含量(P<0.01),降低血糖的浓度(P<0.01);1,6-二磷酸果糖能提高血清谷丙转氨酶和谷草转氨酶活性(P<0.05),提高血清总蛋白、白蛋白和球蛋白的含量(P<0.01);格列本脲能提高血清谷丙转氨酶活性(P<0.05),提高总蛋白、白蛋白和球蛋白的含量(P<0.01)、降低血糖的浓度(P<0.01);③与对照组相比,罗格列酮能提高肌糖原的含量(P<0.05),格列本脲组肌糖原也有提高的趋势。     

Effect of hypoxia on immunological,physiological response,and hepatopancreatic metabolism of juvenile Chinese mitten crab <Emphasis Type="Italic">Eriocheir sinensis</Emphasis>

The juvenile Chinese mitten crabs Eriocheir sinensis (1.40 ± 0.43 g) were cultured in water of 5.34 ± 0.43 (hypoxia, treatment group) and 21.02 ± 0.06 kPa (high dissolved oxygen (DO), control group) DO for 24 h, respectively. The total hemocyte counts (THC), the hyaline hemocyte counts were measured at 0 and 24 h in the treatment group, and superoxide dismutase (SOD) activity, concentrations of lactic acid and hemocyanin (Hc) in hemolymph and the metabolism of hepatopancreas (concentrations of glucose, total cholesterol, uric acid, total protein, urea, triglyceride in hepatopancreas) were assayed at 0, 2, 8, and 24 h in both treatment and control groups. The hyaline hemocyte counts and THC decreased significantly by 66 and 49% after exposure to hypoxic water for 24 h, respectively. SOD activity, Hc and lactic acid content were significantly affected in treatment group, and there were significant differences between treatment and control groups. In the treatment group, the concentration of glucose, cholesterol and uric acid in hepatopancreas had a significant variation for 24 h. The concentration of total protein, urea and triglyceride between treatment and control groups was not significantly different after 0, 2, 8, 24 h. However, there were significant differences between treatment and control groups in terms of total protein, glucose, and uric acid concentration. Taken together, the effect of hypoxia is comprehensive in juvenile Chinese mitten crab Eriocheir sinensis.     

中华绒螯蟹蜕皮过程中肌肉、肝胰脏和甲壳中钙和磷含量的变动

对中华绒螯蟹蜕皮间期和蜕皮后24h、48h和96h肌肉、肝胰脏及甲壳中钙和磷的含量进行了测定。蜕皮后肌肉中钙的含量较间期低，但从24h到48h有所增加。肝胰脏中钙的含量在蜕皮后各时间内无显著变化，甲壳中钙的含量在蜕皮后24h到96h呈增加趋势。甲壳的矿化作用在蜕皮后96h已接近完成。蜕皮后肌肉中磷的含量较间期高，以后变化不明显。蜕皮后肝胰脏中磷的含量高于间期，甲壳中含量较间期低。蜕皮后肌肉中钙磷比迅速降低，肝胰脏中钙磷比在蜕皮后24h无明显变化，但在蜕皮后24h至96h迅速降低。中华绒螯蟹蜕皮后外表皮对钙的矿化速度显著快于磷的矿化速度。     

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in Pacific white shrimp <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis> after multiple-dose oral administration

The present study was designed to explore pharmacokinetics (PK) of enrofloxacin and its metabolite ciprofloxacin in Pacific white shrimp Litopenaeus vannamei after multiple-dose oral administration of enrofloxacin (30 mg/kg dose per 12 h and continuous feeding for 3 days). Enrofloxacin and ciprofloxacin concentrations in hemolymph, hepatopancreas, and muscle of the shrimp were simultaneously determined by high-performance liquid chromatography. PK parameters were analyzed based on statistical moment theory. Meanwhile, the relationship of pharmacokinetics/pharmacodynamics (PK/PD) was established based on drug concentration of hemolymph and in vitro antibacterial activity (MIC value). Results showed faster absorption of enrofloxacin in hemolymph (T_max?=?1 h) and muscles (T_max?=?1 h) than that in hepatopancreas (T_max?=?3 h) after the first oral administration. In multiple-dose oral administration, slight accumulation of enrofloxacin occurred in the hemolymph and hepatopancreas, while in the muscle, enrofloxacin concentration showed a significant decline following multiple administration. Tissue distribution of enrofloxacin and ciprofloxacin both followed the order hepatopancreas?>?hemolymph?>?muscle, with significantly higher ciprofloxacin concentration in hepatopancreas than in hemolymph (approximately 10-fold) and muscles (approximately 50-fold), indicating that the hepatopancreas is the main organ involved in metabolism of enrofloxacin in Pacific white shrimp. After multiple-dose administration, C_max/MIC and AUC_0–24/MIC values showed that the therapeutic regimen in this study could be remarkably effective in prevention and treatment of Vibrio infection in Pacific white shrimp.     

Biochemical responses of matrinxãBrycon cephalus (Günther, 1869) after sustained swimming

Juvenile matrinxã, Brycon cephalus, were submitted to sustained swimming for 72 days at 1.0 body length s^?1. Exercised fish (EF) grew more than non‐EF and their feed conversion ratio (FCR) improved; haematological responses demonstrated a decrease in haemoglobin and mean cell haemoglobin contents and increase in the mean cell volume. In the plasma, sodium, ammonia and amino acid concentrations increased; plasma triglycerides decreased while free fatty acids increased. Liver glucose, free amino acids, ammonia, the rate protein per fish weight and total lipid content increased, while the glycogen per fish ratio declined. Glutamate dehydrogenase (GDH) activity increased while pyruvate kinase (PK) and lactate dehydrogenase (LDH) decreased. White muscle glucose, lactate, the glycogen per fish‐weight ratio and total lipid content exhibited a decrease in their values; ammonia, free amino acids and the protein per fish‐weight ratio increased. GDH and PK decreased their activities. In the red muscle glycogen store, the glycogen per fish‐weight ratio and glucose were reduced. Juvenile matrinxãs, under sustained swimming, were physiologically and biochemically adapted to exercise as indicated by improved blood flow, transport and oxygen uptake, FCR, amino acid and protein incorporation and growth. Continuous exercise is a good practice for B. cephalus cultivation.     

高盐胁迫对黄边糙鸟蛤(Trachycardium flavum)呼吸排泄和免疫酶活性的影响

为了探讨急性高盐胁迫对黄边糙鸟蛤(Trachycardium flavum)生理代谢和免疫酶活性的影响,分析了盐度自31骤升至37后2、12、24、48和72 h黄边糙乌蛤耗氧率、排氨率和不同组织Na+/K+-ATP酶、超氧化物歧化酶(SOD)、酸性磷酸酶(ACP)和碱性磷酸酶(ALP)的活性.结果显示,处理后2h耗氧率先降低,然后逐渐升高,在24和72 h显著高于对照组(P＜0.05);排氨率在2h极显著降低(P＜0.01),且在各时间点均低于对照组.外套膜、肝胰腺中Na+/K+-ATP酶活力在12 h显著降低(P＜0.05),肌肉和鳃中活力与对照组无显著差异.外套膜、肝胰腺和鳃中SOD活力在24 h达到最高值,显著高于对照组(P＜0.05),其后逐渐降低;肌肉中SOD活力在48 h达到最高值后降低.外套膜和鳃中ACP活力先升高后降低,肝胰腺中ACP活力显著降低(P＜0.05)后逐渐升高,肌肉中ACP活力与对照组无显著差异.肝胰腺和鳃中ALP活力先降低后显著升高(P＜0.05),与对照组相比,外套膜和肌肉中ALP活力无显著差异.结果表明,急性高盐胁迫对黄边糙鸟蛤的代谢水平和免疫酶活性均有显著影响且表现出时间效应性,高盐胁迫对免疫酶活性的影响具有组织特异性.     

低氧和复氧对日本沼虾抗氧化酶活力及组织结构的影响

为研究低氧胁迫及恢复后日本沼虾(Macrobrachiumnipponense)抗氧化酶活力和组织结构的变化,将体重(2.0±0.2) g的日本沼虾暴露于(2.0±0.2) mg/L低氧环境中24 h,设定溶解氧(6.0±0.2) mg/L为对照组,每组设置3个重复,于低氧胁迫0 h、6 h、12 h、24 h及复氧1 h、6 h、12 h、24 h分别采集实验组及对照组鳃、肝胰腺及肌肉组织,测定这些组织的抗氧化酶活力,并进行组织切片观察。实验结果表明,低氧胁迫期间肌肉组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)活力先升高后下降, 3种酶活力在低氧胁迫12 h时显著高于对照组(P0.05),复氧阶段肌肉组织中SOD、CAT酶活力呈波动性变化,GPX酶活力在复氧24h时显著低于对照组(P0.05)。鳃组织中SOD、CAT和GPX酶活力在低氧胁迫12 h时显著高于对照组(P0.05), GPX酶活力在复氧24 h时显著高于对照组(P0.05)。在低氧胁迫期间肝胰腺SOD、CAT和GPX酶活力在低氧6 h均达到最大值并显著高于对照组(P0.05),复氧阶段3种酶活力均呈现波动性变化,肝胰腺中丙二醛(MDA)含量在低氧及复氧阶段均显著高于对照组(P0.05)。低氧胁迫及恢复并未对肌肉组织结构产生明显的影响。鳃组织在低氧胁迫期间鳃小片上皮细胞与支柱细胞排列发生紊乱,次级层片发生肥大的现象且有红细胞流入,泌氯细胞形态发生变化且细胞数目有所增加,但复氧后均得到一定程度的恢复。肝胰腺组织在低氧胁迫期间B细胞数量逐渐降低,胞内运转泡体积减小,复氧阶段B细胞数量及体积恢复明显。结果表明急性低氧胁迫能够导致日本沼虾肝胰腺和鳃组织结构损伤并引起抗氧化酶活力发生显著变化,且24 h恢复期不足以让日本沼虾在低氧胁迫中完全恢复。     

亚硝态氮胁迫下凡纳滨对虾体内亚硝态氮的积累与能量代谢响应

为探究亚硝态氮胁迫下凡纳滨对虾[体长为(6.8±0.3) cm,体质量为(4.0±0.6) g]体内亚硝态氮的时空分布与能量代谢相关酶活性的响应,实验设置0(对照组)、0.8、4.0和8.0 mmol/L 4个处理组,进行持续96 h的亚硝态氮胁迫实验和12 h的恢复实验。结果显示,凡纳滨对虾死亡率与胁迫浓度呈现显著的正相关性。胁迫6 h内,亚硝态氮在凡纳滨对虾鳃、血淋巴、肠道、肝胰腺和肌肉组织中明显积累,且积累量与胁迫浓度呈现正相关。相同胁迫浓度组,亚硝态氮在对虾鳃中积累最多,肌肉中最少,鳃中的积累量约为肌肉的3倍。Na~+-K~+-ATP酶活性在0.8和4.0 mmol/L组对虾肝胰腺和肌肉中显著升高,而在8.0 mmol/L组的肌肉中显著降低。胁迫各组对虾肝胰腺AMPK活性显著上升,且与胁迫浓度呈现正相关性。恢复期间,除血淋巴(8.0 mmol/L组)外,各组织中亚硝态氮1 h恢复效率均超过50%,且肝胰腺和鳃的恢复效率最高,达到74%以上。血淋巴、鳃、肠道中亚硝态氮恢复到对照组水平的时间最短,均在6 h以内,而水体中亚硝态氮含量显著升高。以上研究表明,胁迫下亚硝态氮会在对虾组织中迅速积累,并引起能量代谢进程的加快;胁迫解除后,积累在体内的亚硝态氮能够迅速排出体外,以减轻毒性影响。本研究结果将为缓解亚硝态氮对养殖对虾毒性效应的研究提供参考。