ABSTRACT
Clearly, endogenous reporters have been valuable as indicators of mutational activity; however, their utility to date has been limited by the restricted number of tissues in which they serve as useful markers. The reporter genes in predominant, but not exclusive, use are of prokaryotic origin. Bacterial Chloramphenicol Acetyltransferase (CAT), a bacterial enzyme absent in higher eukaryotes has been used extensively to localize tissue specific and ectopic expression when the CAT gene is placed under control of a eukaryotic promoter. Enzyme activity in tissues or cells of transgenic animals can be detected and quantitated by the degree to which tissue lysates will acetylate radiolabeled chloramphenicol. The model is the equivalent of a whole animal Ames test in which every cell in a tester animal will be APRT deficient but revertible. In principle, every cell is a data point, reducing the number of animals required for analysis.
