Karyotyping of Yeast Strains by Pulsed-Field Gel Electrophoresis

Pulsed-field (gradient) gel electrophoresis (now abbreviated to PFGE or PF) was first described by Schwartz and Cantor (1 ) and Carle and Olson (2 ) in 1984. It allows separation of DNA molecules in the size range 50 kb to approx 10 Mb in agarose gels to which electric fields are applied in different directions. The chromosomes of Saccharomyces cerevisiae lie within the approximate size range of 200 kb to 3 Mb and can therefore be separated by this method to provide “electrophoretic karyotyping” of both laboratory-bred (3 ) and industrial (4 ), strains of this and related species. Several other yeasts of various genera, such as Candida albicans and Schizosaccharomyces pombe , have also been karyotyped by this method (4 –8 ).