DNA-Based Toxicity Assay for Pesticides in the Environment

Author(s): Ethelbert Uchechukwu Ezeji, Ikechukwu N. E. Onwurah, Angela C. Udebuani

Increased use of domestic and agricultural pesticides has become a serious threat to the environment. Prolonged exposure to pesticides is capable of affecting the genetic integrity of humans and other animals. The aim of this study is to access the effect of dichlorvos (DDVP), a widely used pesticide in Nigeria, on the DNA of poultry birds (Gallus domestica). This study explored different special representation of treated groups using a three-patch matrix model incorporating dichlorvos contamination (0.01, 0.02 and 0.4%). Exposure was carried out for ten weeks after which the birds were sacrificed and the liver was extracted. Thermal denaturation of the DNA from the exposed birds resulted in a significant reduction (p< 0.01) in the DNA melting temperature from 87.2oC to 81.7oC while the GC/AT ratio was also significantly reduced (p<0.01) from 0.77 in the control to 0.42 in exposed birds respectively. Electrophoresis of isolated DNA in 0.8% agarose gels gave variations in band intensity between the control DNA sample and DNA from exposed birds. These variations in band intensity were more pronounced in the RAPD-PCR products amplified with OPE-01 primer, where there is complete disappearance of DNA bands in the birds exposed to 0.04% pesticide. Thus deletion of DNA segments of birds exposed to dichlorvos can be modelled as a molecular biomarker of genotoxicity. This may also suggest that insecticides are capable of impacting genotoxic effects on non-target populations with consistent, long-term use.

Pesticides, genotoxicity, RAPD-PCR, melting temperature, DNA strand breaks.

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