Development of Environmental Risk Assessment System

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The DNA microarray techniques are useful method to determine toxicological effects of xenobiotics, such as drugs and environmental chemicals, on the cells or experimental animals. To clarify the usefulness of DNA microarray method for wildlife samples, we collected wild Norway rats (rats) from urban areas, landfill and isolated island in Japan. Laboratory rats (Wistar) were used as control animals in this study. We measured the accumulation levels of polychlorinated dibenzo-p-dioxins (PCDD), furans (PCDF), polychlorinated biphenyls (PCBs), and organochlorine insecticides. We also examined the residue levels of polybrominated diphenyl ether (PBDE) in rat livers, which are used as flame retardants in plastics and rubbers. Additionally, we screened the alterations of mRNA in liver and testis of wild rats using DNA chip technique, and reported the relationships between accumulated contaminants and expression profiles of RNA. In this study, we also showed the genes which can be used as biomarkers.To develop the DNA microarray for wild animals, we collected samples of wild and captive animals to compare the gene sequences. We cloned P450 and nuclear receptor genes from broad spectrum mammalians, birds and amphibians. We elucidated the possibility of microarray development for several wildlife species.In current study, we also aimed at establishment of functional array which can assess the affinity of environmental chemicals to nuclear receptors. We determined the ligand affinities of nuclear receptors and cross-talk among xenobiotic receptors, e.g., arylhydrocarbon receptor, constitutive active receptor and peroxisome proliferator-activated receptors.