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Abstract T he 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 some 10 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 .155 mg/L in 48 h ,and 19 .317 mg/L in 96 h ,with safe concentration of 4 .068 mg/L calculated by for‐mula(48 h LC50 × 0 .3)/(24 h LC50/48 h LC50 )2 and 1 .0155 mg/L estimated by formula 96 h LC50 × 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 w hole 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 residu‐al nuclear material scattered distribution in the grass carp exposed to Zn 2+ ,thus leading to cell necrosis . With the increase in Zn2+ concentration and time ,the activity of SOD in the hepatopanceas of grass carp w as decreased .
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Received: 25 April 2016
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