Detecting carcinogens with the yeast DEL assay.

The yeast DEL assay is a simple, rapid method for measuring the frequency of reversion of a disrupted his3 gene by homologous intrachromosomal recombination. Reversion to histidine prototrophy results in deletion (DEL) of the disrupting sequence. The DEL assay has been used to study the effects of various DNA-damaging treatments on the frequency of deletion-recombination and has been shown to have a high level of sensitivity and specificity toward carcinogens, many of which are poorly detected by bacterial mutagenicity and other short-term genotoxicity assays. The DEL assay therefore is a useful addition to the arsenal of predictive tests for genotoxicity and carcinogenicity. This chapter provides an in-depth description of materials and methods for the yeast DEL assay from a user's prospective and should allow the assay to be successfully deployed in any laboratory with basic microbiological capability and minimal user training.