Preliminary analyses of biomarkers of the exposure to dioxins and dioxin-like substances in dairy cattle

The term “dioxins” designates a group of toxic chemicals including a number of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) capable of binding to the Ah receptor (AhR). They are very dangerous environmental contaminants of industrial origin due to both their long biological half-life in humans (>7 years) and a number of well recognized toxic properties (carcinogenicity, and alterations of the endocrine, immunological and reproductive systems). At the moment, the analytical procedures to quantify the dioxin contamination in food are time consuming, difficult and expensive, in that they involve complete extraction of the lipidic fraction from complex matrixes. The analysis of target genes expression in circulating lymphocytes could be a fast and economic alternative. In order to develop new analytical tools to assess dioxin contamination in dairy cattle, we have designed 5 specific primer pairs for RT-PCR. RNA from peripheral fresh whole blood was extracted with QIAamp RNA Blood Mini Kit (QIAGEN). All primer pairs amplified fragments of the expected size. Fragments sequences showed a 100% homology with reference sequences. The primer pairs we designed will be used to develop a Real Time PCR protocol in order to analyze the target genes profiles in circulating lymphocytes from dairy cows reared in a dioxin contaminated area of Northern Italy.