Investigating Fission Yeast Mutagenesis Using Canavanine Sensitivity Assays

Fission yeast are genetically tractable and amenable to mutagenesis studies. Canavanine is a toxic antimetabolite that can be used to test mutation rate. Recent studies have shown that the molecular genetics of canavanine sensitivity are more complex than previously anticipated. However, genomics advances indicate that canavanine use to determine mutation remains an option. In this chapter, we provide methods to grow fission yeast and detect forward mutation in populations of canavanine-sensitive Schizosaccharomyces pombe. Wild-type S. pombe are functionally canavanine-sensitive and die in the presence of canavanine. These protocols use liquid cultures that are tested for density and viability through colony formation. The same cultures are plated onto canavanine-containing media. Cells are grown to find cells that can grow on the canavanine media. These resistant cells are compared to the number plated, and a mutation rate is calculated. While the protocol is straightforward, analysis and application of the data are evolving. These methods provide the ability to compare S. pombe mutant strains for the frequency and rate of mutation.