Revolution through genomics in investigative and discovery toxicology

The remarkable technologic and methodologic advances spurred on by the Huma n Genome Project are being applied throughout the life sciences. In the fie ld of toxicology, high-resolution assays now make it possible to discover v irtually all the differences in gene expression brought on by exposure to a particular xenobiotic. There are 2 principal approaches used to build a ca talog of changes in gene expression: hybridization microarrays and gel-base d methods, such as differential display and AFLP(TM)-based mRNA fingerprint ing. The power of such approaches is exemplified by the identification of m ore than 300 genes that differ in expression level by at least 2-fold in re sponse to the nongenotoxic rodent liver carcinogen phenobarbital.