Absolute Transcript Expression Signatures of Cyp and Gst Genes in Mus spretus to Detect Environmental Contamination

Abstract

We evaluated whether quantitation of mRNA molecules of key genes is a reliable biomonitoring end-point. We examined the Mus spretus expression levels of 19 transcripts encoding different cytochrome-P450s and glutathione transferases. Mice dwelling at the Doñana Biological Reserve were compared to those from an industrial settlement (PS). Metal biomonitoring indicated that PS animals sustained a heavier pollutant burden than those from the reference site. Transcript quantitations showed the following: (i) gender-related differences in the expression of most Cyp and Gst genes; (ii) one PS female displaying much smaller/larger transcript amounts than the remaining females; (iii) the concomitant up-regulation of Cyp1a2, Cyp2a5, Cyp2e1, Cyp4a10, Gsta1, Gsta2, Gstm1, and Gstm2 mRNAs in liver of PS males; and (iv) outstanding qualitative and quantitative differences between the hepatic expression signature of PS males and that promoted by paraquat. We conclude that (i) absolute amounts of transcripts encoding biotransformation enzymes are more potent biomarkers in males than in females, and in liver than in kidney; (ii) individual quantitations prevent biased interpretations by specimens with abnormal expression levels; and (iii)transcript expression signature of PS males is consistent with exposure to a complex profile of organic pollutants, other than oxidative stressors.