Development and application of molecular biomarkers for ecotoxicological monitoring in Stenella coeruleoalba (Cetacea, Odontoceti)

Most xenobiotic compounds are widespread in the environment and can affect animal health at different biological levels since they tend to be persistent in the environment and biota being therefore accumulated in the organisms. Mediterranean cetacean odontocetes are potentially at serious to hazard, due to exposure to POPs (persistent organic pollutants), PBDEs (polybromodiphenyl-ethers) and PAHs (polycyclic aromatic hydrocarbons). In the present study, the response of gene expression biomarker has been evaluated in Mediterranean striped dolphin (Stenella coeruleoalba) skin biopsies or slices of skin biopsies exposed to different doses and different mixtures of toxic compounds. The mRNA levels of five putative biomarker genes (AHR, CYP1A, E2F-1, ER-α, and HSP70) were measured by quantitative Real Time PCR (qRT-PCR). An accurate selection of control genes was previously carried out in all tissues analyzed to ensure the reliability of our data. The “geneexpression biomarkers” exhibit a sensitive response in all tissues analysed, confirming the molecular approach as a suitable tool in this kind of studies. The specimens, coming from two regions of Mediterranean Sea and a contiguous area with different toxicological impacts (Pelagos Sanctuary, Ionian Sea, and Strait of Gibraltar), were analyzed by qRTPCR. The response of most biomarker genes tested reflects the contamination levels of the three regions showing a differential response to different classes of environmental contaminants across Mediterranean basin. In addition, an in vitro assay was developed to show the different susceptibilities of cell cultures and slices from striped dolphin skin biopsies exposed to different classes of compounds.