| The research used Ctenopharyngodon idellus and Cyprinus carpio as the experimental object,investigated effects of exposure of manganese on the oxidative damage and antioxidant capacity of Ctenopharyngodon idellus and Cyprinus carpio,under the condition of temperature(27.5 ± 0.5)?in aeration water.The experiment consists of two parts.The first part is the exposure of manganese acutely toxicological experiments: according to the pre-experiment,we measured bivalent manganese on semi-lethal concentration(96 hLC50)of Ctenopharyngodon idellus and Cyprinus carpi in the water.The second part is subacutely toxicological experiments of exposure of manganese:According to the 96 hC50 determined by acutely toxicological experiments,Ctenopharyngodon idellus and Cyprinuscarpio were exposed to water bodies with different concentrations of manganese(0,30,60,120,240 mg/L).We measured the T-AOC level in the liver,gill,digestive tract and kidney of the Ctenopharyngodon idellus and Cyprinus carpio,the activities of CAT and MDA in the liver,gill and digestive tract of the Ctenopharyngodon idellus and Cyprinus carpio,the activity of AChE in the brain tissue,and the contents of total protein in the liver,gill,digestive tract and kidney of Ctenopharyngodon idellus and Cyprinus carpio.The main results of this experiment are as follows:(1)In the acutely toxicity test of exposure of manganese,we found that the mortality of Ctenopharyngodon idellus and Cyprinus carpio increased with the increment of concentration of manganese in the water,and the 96 hLC50 of bivalent manganese to Ctenopharyngodon idellus and Cyprinus carpio were 541.07 mg/L and 577.27 mg/L.(2)Effects of exposure of manganese on the liver of Ctenopharyngodon idellus and Cyprinus carpio.(1)The content of MDA in the liver of Ctenopharyngodon idellus and Cyprinus carpio was increased with the incresment of the concentration of manganese after 30 days.After the linear regression analysis,the content of MDA in the liver of Ctenopharyngodon idellus at all treatmentgroups was significantly higher than that in the control group(p<0.05).The contents of MDA in the liver of the Cyprinus carpio at treatment groups were significantly higher than that in the control group(p<0.05)except the group of the concentration of 30 mg/L.(2)The T-AOC of Ctenopharyngodon idellus and Cyprinus carpio increased firstly and then decreased with the incresment of concentration of manganese in the water for 30 days.The T-AOC of the Ctenopharyngodon idellus was the largest at the concentration of 60mg/L,which had no significant difference with the control group,and the T-AOC was the lowest at concentration of 240 mg/L,which was significantly lower than the concentration of 60 mg/L(p <0.05),and had no significant difference with the control group and others.The T-AOC of Cyprinus carpio was the largest and significantly different with that of control group and others at the concentration of 60 mg/L(p <0.05).(3)The CAT in Ctenopharyngodon idellus and Cyprinus carpio increased firstly and then decreased with the increase of concentration of manganese in the water after 30 days.The CAT in Ctenopharyngodon idellus at the concentration of 60 mg/L was largest and significantly different with that in control group and others(p<0.05).The CAT in Cyprinus carpio at the concentration of60 mg/L was largest and had no significantly different with that in control group,but was significantly different with others except the group of the concentration of 30 mg/L(p <0.05).(3)Effects of exposure of manganese on the gills and gastrointestinal of Ctenopharyngodon idellus and Cyprinus carpio.After exposuring in the water of different concentrations of manganese for 30 days,the changes of MDA content,T-AOC level and CAT activity in gills and digestive tracts of Ctenopharyngodon idellus and Cyprinus carpio were similar to those in the livers.The content of MDA in the gills of Ctenopharyngodon idellus was significantly higher than that in control group(p<0.05),the content of MDA in the digestive tracts of Ctenopharyngodon idellus had no significantly different with the control group(p<0.05),but other groups had significantly different witth the control group(p<0.05).The changes of contents of MDA in the gills of the Cyprinus carpio rase slowly,and the other groups was significantly different with that in the control group except the group of concentration of 30 mg/L(p<0.05);and the contents of MDA in the digestive tracts of he Cyprinus carpio was significantly higher than that in the control group(P<0.05).The contents of T-AOC in the gills and digestive tracts of Ctenopharyngodon idellus and Cyprinus carpio was the highest at the concentration of 60 mg/L,less than this concentration for the upward trend,greater than this concentration for down trend.The activity of CAT of Ctenopharyngodon idellus and Cyprinus carpio was the highest at 60 mg/L concentration,which was significantly higher than that in the control group(p <0.05).(4)Effects of exposure of manganese on the acetylcholines of Ctenopharyngodon idellus andCyprinus carpioThe activity of AChE in the brain tissue of Ctenopharyngodon idellus and Cyprinus carpio decreased with the incresment of the concentration of manganese.The activity of AChE in the brain of Ctenopharyngodon idellus decreased rapidly at the low concentrations,but decreased slowly at the high concentrations,AChE activity had no significant difference at the concentration of 240mg/L with the concentration of 120 mg/L.The activity of AChE in the brain of Cyprinus carpio was decreased slowly,and the activity of AChE was significantly different from that of the control group at the concentration of 240 mg/L.The conclusions from the discussion:(1)The literature and acute experiments showed that the exposure of manganese in water is toxic to Ctenopharyngodon idellus and Cyprinus carpio.(2)The content of MDA in the tissues of Ctenopharyngodon idellus and Cyprinus carpio and the concentration of manganese in water showed a linear relationship by regression analysis,so the content of MDA could be used as a biological index to indicate the index of the heavily metallic pollution in water.The AChE in the brain tissue of Ctenopharyngodon idellus and Cyprinus carpio was sensitive to the concentration of manganese in the water,and decreased with the incresment of the concentration.It also could be used as a biological indicator to indicate the index of the heavily metallic pollution in water.(3)The activity of T-AOC in the tissues of Ctenopharyngodon idellus and Cyprinus carpio had small changes,but the activity of enzyme changed largly,and the activity of the same enzyme showed differently in the different tissues of the different concentration of manganese.(4)After 30 days of exposure of manganese in water,The content of MDA in Ctenopharyngodon idellus and Cyprinus carpio showed a concentration-effective relationship.The content of T-AOC and the activity of CAT increased firstly and then decreased,in general,they showed the function of induction at low concentration,While at the high concentration,the dynamic balance of antioxidantly defensive system was broken,showed the inhibition.(5)After conditons of same concentration of manganese in the same exposure time,the oxidative damage of Ctenopharyngodon idellus were as follows: liver> digestive tract> gill,the antioxidant capacity of Ctenopharyngodon idellus were as follows: gill> liver> kidney> digestive tract;and the oxidative damage of Cyprinus carpio were as follows: digestive tract> liver> gills,the antioxidant capacity of Cyprinus carpio were as follows: liver> digestive tract> gill> kidney.The reason for it may be that the tolerance of different species of fishes to the same kind of heavymetalcontaminants is different and the antioxidant capacity is related to the specificity of the different tissues of fishes. |
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