Abstract: BACKGROUND ＆ AIM: For the non-radioactive, sensitive and rapid detection of the dioxin-like chemicals in the environmental samples, exonuclease protection mediated PCR assay was established. MATERIAL AND METHODS: 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) dissolved in DMSO, a typical and the most toxic ligand to transform AhR, was added into SD rat hepalic cytosol in vitro, which contained Ah receptors and relative proteins, and ligand-AhR-DRE complex are formed in addition of DNAs containing the sequence of DRE.With the digestion of Exonuclease Ⅲ and S1 nuclease, free DNAs were digested to mononucleotide and bound DNA remained due to protein(AhR) protction and could be amplified by PCR.The effects of PCRs were shown by loading on 2 ％ agarose electrophoresis.DMSO was used as negative control was set up. RESULTS： Target DNA could be observed in the TCDD groups, but not in the control group. CONCLUSIONS： Exonuclease protection mediated PCR assay is a good non-radioactive tool to quantify the interaction of protein and DNA with high sensitivity and simple.

Key words: dioxin-like chemicals;aromatic hydrocarbon receptor;dioxin responsive element;exonuclease Ⅲ, S1 nuclease