悬浮物对半滑舌鳎(Cynoglossus semilaevis)幼鱼肝脏溶菌酶、超氧化物歧化酶和鳃丝Na^＋-K^＋ATPase活力的影响

EFFECTS OF SUSPENDED SUBSTANCE CONCENTRATION ON ACTIVITIES OF LYSOZYME, SUPEROXIDE DISMUTASE, AND Na^+-K^+-ATPase IN JUVENILE CYNOGLOSSUS SEMILAEVIS

在实验室条件下构建不同的悬浮物浓度环境,采用试剂盒分析方法研究了不同浓度悬浮物对半滑舌鳎幼鱼肝脏溶菌酶(LSZ)、超氧化物歧化酶(SOD)和鳃丝Na+-K+-ATPase活力的影响。养殖水体中悬浮物浓度添加量分别为0(对照)、50、100、200和400mg/L,每5天采样测定一次,实验周期为25天。结果表明,当悬浮物浓度添加量为50和100mg/L时,肝脏LSZ和SOD活力与对照组无显著差异(P>0.05),当添加量为200和400mg/L时,肝脏LSZ和SOD活力与对照组有显著差异(P<0.05);实验后期各实验组鳃丝Na+-K+-ATPase活力与对照组均有显著差异(P<0.05)。在悬浮物效应的25天内,各实验组肝脏LSZ活力呈峰值变化,10天时除100mg/L浓度添加组外均达到最大值;而肝脏SOD活力在50和100mg/L浓度添加组略有升高,在200和400mg/L浓度添加组则基本呈下降趋势;鳃丝Na+-K+-ATPase活力前10天各实验组较对照组无显著变化,之后则显著降低,后期基本趋于稳定,其活力低于初始水平;实验结束时,各实验组其肝脏LSZ、SOD和鳃丝Na+-K+-ATPase活力相对于对照组都受到了不同程度的抑制,其中各实验组鳃丝Na+-K+-ATPase活力抑制率分别达到了27.6%、65.2%、57.0%和71.1%。

Changes i.n activities of lysozyme （LSZ）, superoxide dismutase （SOD）, and Na^＋-K^＋-ATPase in the liver and gill of juvenile Cynoglossus semilaevis Gtinther were studied in different concentrations of suspended substances （0, 50, 100, 200 and 400mg/L）. The experiment was conducted in 80L plastic tanks （60cm×40cm×40cm in dimension）, each containing 30 fish. The sizes and weights of the fish were at （8.09±0.46）cm and （4.98±0.64）g, respectively. The experimental condition was pH 8.15±0.04, salinity 30.68±0.16, temperature （20.9±0.63）℃, DO （7.03±0.33）mg/L, NH4-N （0.085±0.009）μmol/L, NO2-N （0.155±0.027）μmol/L, and NO3-N （8.56±0.605）μmol/L. Daily bait was fed at 3%--4% of the body weight. The suspended substance used as the experimental mud was taken from a local muddy beach, dried, grinded, and sieved by 400-mech （≤38μm）, and the concentration was set at 25.5 （the control）, 50, 100, 200, and 400mg/L. Sampling was conducted at Days 0, 5, 10, 15, 20 and 25, and the samples were stored at -80℃ until enzymes were assayed. The results show that the effects of suspended substance were significant （P〈0.05）, especially at high concentration （200 and 400mg/L）, on the activities of liver LSZ and SOD, gill Na^＋-K^＋-ATPase in juvenile C. semilaevis. During the 25 days, the liver LSZ activity increased at first and then decreased, on the Day 10, the peak values appeared in the groups of 50, 200 and 400mg/L, and the minimum ones appeared on Days 20 and 25; both liver SOD and gill Na^＋-K^＋-ATPase activities decreased gradually. At the end of the experiment, activities of all the enzymes in each group stabilized. Compared with the control group, the inhibition rate of activities of the three enzymes increased gradually with the increase in the concentration of suspended substance, and the maximum values of liver LSZ increased 35.3% at 200mg/L, liver SOD 33.7% and gill Na＋-K^＋-ATPase at 400mg/L 71.1%, respectively.