不同质量浓度Zn^(2+)对草鱼脑、肝胰脏组织结构及肝胰脏中超氧化物歧化酶活性的影响

Effects of Different Concentrations of Zinc Ion on Histological Structure of Brain and Hepatopancreas and Hepatopancreatic SOD Activity in Grass Carp Ctenopharyngodon idellus

水温(20±1)℃,采用静水测试法研究了养殖水体中不同质量浓度Zn2+(0、9.52、13.14、18.30、25.02、34.53mg/L)对体质量约10g的草鱼脑和肝胰脏的组织结构及肝胰脏中超氧化物歧化酶活性的影响,探讨重金属的毒性积累和毒性机制。试验结果表明,Zn2+对草鱼的24、48h和96h半致死质量浓度分别为23.058、19.317、10.155mg/L,由公式(48hLC50×0.3)/(24hLC50/48hLC50)2和96hLC50×0.1计算出安全质量浓度分别为4.068mg/L和1.0155mg/L。中毒初期草鱼脑细胞轻微聚集,细胞核微增大;随时间延长脑异常加重,细胞聚集明显,核增大几乎充满整个脑细胞;肝胰脏细胞膨大,离散,核缩小,胞浆轻微溢出,少数肝胰脏细胞胞浆溢出,残留的核物质散乱分布,肝胰脏细胞凝固性坏死。随着Zn2+质量浓度的升高和时间延长,草鱼肝脏中超氧化物歧化酶活性降低。

The influences of different concentrations of zinc ion（Zn2＋）（0,9.52,13.14,18.30,25.02,and 34.53 mg/L）on histological structure of brain and hepatopancreas and superoxide dismutase（SOD）activity in hepatopancreas were studied in grass carp Ctenopharyngodon idellus with body weight of some10 g at water temperature of（20±1）℃ by a hydrostatic test to seek for the accumulation and toxicity mechanism of heavy metals.It was found that the LC50 of Zn2＋to grass carp was 23.058 mg/L in 24 h,10.155mg/L in 48 h,and 19.317mg/L in 96 h,with safe concentration of 4.068mg/L calculated by formula（48hLC50×0.3）/（24hLC50/48hLC50）2and 1.0155mg/L estimated by formula 96hLC50×0.1.In the early stage of Zn2＋poisoning,the grass carp exposed to Zn2＋had clustered brain cells with the slightly enlarged nuclei,and as the time elapsed,the brain cells aggregated significantly,and the whole brain cells were almost filled with the nuclei.The hepatopancreas cells were found to be expansion,discrete,nuclear reduction,a slight overflow of the cytoplasm,a small number of liver cell cytoplasm overflow,and residual nuclear material scattered distribution in the grass carp exposed to Zn2＋,thus leading to cell necrosis.With the increase in Zn2＋concentration and time,the activity of SOD in the hepatopanceas of grass carp was decreased.