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| Effects of Concentrations of Chromium Ion on Histological Structure of Brain and Hepatopancreas and Hepatopancreatic SOD Activity in Grass Carp |
| REN Hongtao,LIN Lin |
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Abstract In the experiment ,the influence of different concentrations of Cr6+ (120 .00 ,160 .80 ,215 .47 , 288 .73 ,and 386 .90 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 metal .It was found that the LC50 of Cr6+ to grass carp was 302 .77 mg/L in 24 h ,154 .47 mg/L in 48 h ,and 78 .89 mg/L in 96 h ,with safe concentration of 12 .068 mg/L calculated by formula(48 h LC50 × 0 .3)/(24 h LC50/48 h LC50 )2 and 7 .489 mg/L estimated by formula 96 h LC50 × 0 .1 .In the early stage of Cr6+ poisoning ,the grass carp exposed to Cr6+ had clustered hepatopancreas cells with slightly enlarged nuclei and the slightly exhibited cytoplasm .As the time elapsed ,the significantly aggregated hepatopancreatic cells showed obvious hypertrophy and disorder discrete .The nucleus was rel‐atively narrow in shape ,and the cavitation .The brain cells were found to be expansion ,discrete ,nuclear reduction ,a slight overflow of the cytoplasm ,a small number of brain cell cytoplasm overflow ,and resid‐ual nuclear material scattered distribution in the grass carp exposed to Cr 6+ ,thus leading to hepatopancre‐atic cell necrosis .With the increase in Cr6+ concentration and time ,the activity of SOD was decreased in the hepatopanceas of grass carp .
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Received: 25 June 2016
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