| The pyrethroid, as a kind of pesticide, is not only used as cleaning pond drugs in aquaculture, but also have good effectiveness on preventing anchor magna, cootie and other carapace parasite of fish, so the quantities also become more and more on aquaculture and agriculture. This pyrethroid is harmless to the fish which could inhale the toxicity easily from the gill because of it's liposoluble, so choosing the sensitive index for evaluating the toxicity of the pesticide scientifically are very significant.The 96h-sub-lethal concentration, the toxicity of oxidative damage and the histopathological damage of the one year carps which exposing to fenvalerate were studied by acute toxicity experience and subacute toxicity experience. These could be important for evaluating the toxicity of this pesticide in the disease control of aquatic animal and accumulating scientific data for the fishery drugs. First, the acute toxicity of fenvalerate on carpsAccording to the previous trials, five concentrations (10,20,40,80,160g/L) and one control group were setted. Sub-lethal concentration was 50.35ug/L through the modified Korbor. Based on the toxicity grading standards, fenvalerate was highlytoxic to the one year carps. Second, the effect of fenvalerate on the antioxidant defense system of carpsThe carps exposed to fenvalerate of different concentrations (0,0.8,1.8,4.05,9.11,20.25 ug/L)for 21 day. The liver and serum were sampled on the 1,3,7,14,21days and the activity of superoxide dismutase(SOD), catalase(CAT) and the lever of malondialdehyde(MDA) in different tissues of carps have been detected through microplate reader. The results about the activity of SOD in the liver of carps show that:it is not different between the control group and the 0.8ug/L of fenvalerate, but the activity in the other concentrations were rising and reaching to the maximum in the 3days, then decreased quickly. The activity in the other concentrations were significant inhibition when the fish exposed to fenvalerate for 21 days. The results of activity of SOD in the serum show that, it is not different between the control group and the 0.8ug/L of fenvalerate although it was increased on the 14days. The activity in the other concentrations all rised first then decreased, that were all under the control group and significantly inhibited except the concentration of 1.8ug/L on the 21 days. The results about the activity of CAT in the liver of carps show that, it is not different between the control group and the 0.8ug/L of fenvalerate. The activity of CAT decreased when the fish exposed in the concentrations of 1.8ug/L, then recovery to the control group lever. The activity were inhibited when the fish exposed to the other concentrations and decreased to minimum on the 7days. On the 2Ids the activity were all under the control group lever. The results about the activity of CAT in the serum show that, it is not different between the control group and the 0.8ug/L of fenvalerate. The activity of CAT reached to the maximum on the 3days when the fish exposed to 1.8ug/L, 4.05ug/L and 9.1 lug/L, then decreased. On the 21 days it was significantly lower then the control group. The activity of CAT was 39.47%to the control group when it decreased consecutively from the beginning of exposing in the concentrations of 20.25ug/L.The results of the lever of MDA in the liver show that, it is not different between the control group and 0.8ug/L of fenvalerate although it rised slightly from 7days to 21 day. The lever of MDA in the other concentrations rised from 3 days to 21 days when the fish exposed to the other concentrations of fenvalerate, Excepting the lever of MDA in 1.8ug/L.9.1lg/L decreased on 21days. The results of the lever of MDA in the serum show that, it is not different between the control group and the 0.8g/L of fenvalerate. The lever of MDA rised consecutively from the beginning of exposing to the concentrations of 4.05(j.g/L-.9.11(j.g/L and 20.25ug/L, at the same time the lever of MDA rised at the 3days when the fish exposing to 1.8ug/L. On 21 days, the lever of MDA in the other four concentrations were 17.65%.67.52%.64.46%.91.05%higher than the control group respectively.Third, the effect of fenvalerate on the histopathological damage.The toxicity and the effect on histomorphology of liver and kidney of carps which exposed for 21 days in four different test concentrations (0.0.8.4.05.20.25ug/L) of fenvalerat had been studied by watching the changes of behavior, and the pathologic examination of liver and kidney which exposing for K 3.7.21 days. The results indicated that the exposed fish displayedjateral swimming, body nigrescence, exophthalmos, defluvium of scales, cyrtosis of fishtail. It is the obvious neurologic toxicity symptoms. The result of hematoxylin-eosin dyeing assay showed that in the liver, it appeared following symptoms, sinusoids enlargement, hemorrhage, vacuolization of hepatocytes and, hepatic necrosis and the formation of lesions was arouse by the dissolution of the cells; The main symptoms in the kidney of carp, renal interstitial cells increased and lymphocytic cell infiltrated, some renal tubular and basement membrane separated, renal tubular cells hydropic degenerated. The glomerulus shrunk and large of hemosiderin deposited when the high concentration group were exposed for 21 days. The process from quantitative change to qualitative change was showed by the damage of tissue and cells, it indicated that the damage to the liver and kidney is not only related to the concentration, but also the effect of time accumulation. The ultramicroscopical observation of high concentration fenvalerat intoxicated liver cells for 21 d shows that, the marginal heterochromatined, the rough endoplasmic reticulum swelled, loosed even fratured, the tubule of smooth surfaced endoplasmic reticulum dissociated to vesicles or expanded into big bubble, and large of the vacuoles and lipid droplets in the cytoplasm. That just proved the result of the cell damage by the microscope. |
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