The alcohol dehydrogenase (ADH) system of the yeast Saccharomyces cerevisiae will be used to isolate ADH2 and ADH4 amplifications in a single selection step and estimate primary amplification rates for ADH2 and ADH4. A duplication of ADH2 (Paquin and Williamson, unpublished data) and an amplification of ADH4 (Walton, Paquin, Kaneko and Williamson, 1986) have been isolated. The ADH system, in conjunction with the tools of genetics and molecular biology available in Saccharomyces cerevisiae, will provide a unique opportunity to investigate primary amplification mechanisms at the single cell level in a simple, eukaryotic organism. An understanding of the mechanisms utilized for gene amplification is of obvious fundamental importance but there are also practical ramifications. There have been demonstrations that in some cases the acquisition of drug resistance is the result of gene duplication. It is also true that in other examples, the phenotype of an organism is related to the number of gene copies. Thus, insight into the mechanisms involved can suggest approaches to practical problems as well as increasing our understanding of genetic mechanisms.
