Physical Characterization of the Chromosomal DNA of the Yeast <italic>Saccharomyces exiguus</italic>

Abstract

The number of chromosomes in the yeast Saccharomyces exiguus was determined to be thirteen by two-dimensional pulsed-field gel electrophoresis. The thirteen chromosomes ranged in DNA size from 520 to 2,600 kbp, with a total length of approximately 14 Mbp. Numbers I to XIII were assigned to the chromosomes in decreasing order of DNA length. Southern hybridization analysis using total DNAs from S. exiguus and S. cerevisiae as probes showed that there was no significant homology between the chromosomal DNAs of the two species, except in the case of the chromosomal DNA that included rDNA. When rDNA and genes LEU2, TRP1, URA3 and HO of S. cerevisiae were used as hybridization probes, it was apparent that S. exiguus had DNA sequences homologous to the rDNA and to the LEU2 and HO genes. In S. exiguus, rDNA-like and LEU2-like DNAs were located on chromosomes I and IX, respectively, and HO-like DNA was located on chromosome VI or VII.