The Study Of Single And Jiont Exposure Of Atrazine And Chlorpyrifos On Toxicological Effects In Common Carp

Application of herbicides and pesticides in agricultural production is widespread, which results in environmental pollution and increases the complexity of evaluating effects of pesticides on environmental and ecological systems. Atrazine(ATR) and chlorpyrifos(CPF) are triazine herbicides and Organophosphate insecticides, respectively, and are widely used in agricultural production, they get into the water via surface runoff, leaching and dry / wet deposition, etc., they directly influence on large aquatic plants and phytoplankton, meanwhile, bring a certain toxicological effects on fish and other aquatic animals. Recent years, the two pesticides are widely noticed because of their large amount of use, long residual period, high detection rate of water environment and some toxicity effects on animals. Since toxicity of ATR and CPF on aquatic invertebrates is investigated rarely, this paper studied the toxicity of single and combined exposure on common carp. In addition, this study also investigated effects of sub-chronic exposure of ATR and CPF , ATR (4.28μg / L, 42.8μg / L and 428μg / L), CPF (1.16μg / L, 11.6μg / L and 116μg / L) and the two combined exposure (1.13μg / L, 11.3μg / L and 113μg / L)on antioxidant(SOD, CAT, GPx, MDA), biochemical(ATPase, GSTs, AChE, CbE), organizational structure, gene expression(GSTT, GSTK, GSTR, GSTM, HSP70, AChE), estrogenic effects (serum E2 levels, liver VtgII and ER-a mRNA expression) and residual in different organs. The results showed that:1. The study of acute toxicity of ATR and CPF on common carp demonstrated that LC50 of ATR tested in different time points were 8.433 mg / L (24 h), 5.346 mg / L (48 h), 3.189 mg / L (72 h), 2.142 mg / L (96 h), while LC50 of CPF were 1.538 mg / L (24 h), 1.309 mg / L (48 h), 0.840 mg / L (72 h), 0.582 mg / L (96 h) and LC50 of mixture of them, concentration ratio of 1:1, were 1.330 mg / L (24 h), 1.299 mg / L (48 h), 0.971 mg / L (72 h), 0.565 mg / L (96 h), respectively. Their safe concentrations were 0.214, 0.058 and 0.057 mg/L, respectively. Toxicity level followed highly toxic, toxic and toxic according to pesticide toxicity grading criteria.2. Single and combined exposure of ATR and CPF could induce the injury in liver, brain, kidney and gill, and reduce physiological function. The differences of histopathologic structure change provided a morphological basis for judging and analyzing the toxicity of ATR and CPF and the joint toxicity of them after exposed to different concentrations.3. Single and combined exposure of ATR and CPF could induce oxidative stress of carp body, decreased CAT, GPx, SOD activity and increased MDA content, thereby destroyed the body's antioxidant defense system and free radical scavenging capabilities, resulted in oxidative damage of carp tissues and affected their normal physiological function.4. Biochemical enzymes detection showed that Na+/ K+-ATPase activity in all treatment groups were lower than that in control group at the end of both exposure and recovery, while Mg2 +-ATPase activity decreased significantly(P<0.05)only in high dose group; AChE activity in brain and muscle was more sensitive than that in liver, kidney and gill, and AChE activity inhibition effect in combined exposure group was more than that in single exposure; CbE activity in liver, brain and muscle also changed. With the increase of exposure dose, GSTs activity had a tendency to decrease, these results showed that ATR and CPF single and combined exposure could affect the changes of related enzymes.5. Detection of serum E2 content and liver VtgII and ER-a mRNA expression indicated that ATR had estrogenic effects at a certain concentration, CPF could increase E2 gene content and ER-a mRNA expression, but decrease VtgII mRNA expression.6. In the experimental concentration range of atrazine and chlorpyrifos, GST subtypes and HSP70 mRNA gene expression were downward or upward, which indicated that GST subtypes and HSP70 genes played an important role in ATR and CPF toxicity.7. Residue test results showed that with the increase of exposure dose, detection of ATR and CPF and their metabolites increased at the end of exposure, after 20 d recovery treatment, tissue residues of pesticides and their metabolites were significantly lower than that of exposed end, but were still detectable, and residue of each organ was different, which indicated that ATR and CPF enriched in various tissues and organs in the form of prototype or metabolites after entered into the carp and their enrichment abilities in different organs were different.In conclusion, ATR and CPF were highly toxic and toxic pesticides to common carp, respectively. whether exposed to ATR and CPF single or combined, in certain concentrations and exposure time conditions, ATR and CPF and their metabolites could be detected in all tissues and could cause the pathological damage and inhibit the activities of detoxification enzymes (AChE, GSTs and CbE) and ATPase, induced oxidative stress, destroyed antioxidant defense system and free radical scavenging function, and also certified that ATR and CPF had high toxicity effects on common carp at molecular level. At the same time, estrogenic index induced in the research after exposed to ATR, indicated that ATR had estrogenic effect; Study on CPF found that CPF only affected E2 content and increased ER-a mRNA expression to some extent, while had little effect on VtgII mRNA gene expression, we think CPF may have estrogenic effects.