Physical and genetic mapping of Candida albicans: several genes previously assigned to chromosome 1 map to chromosome R, the rDNA-containing linkage group

Analysis of the karyotypes of multiple Candida albicans isolates by pulsed-field electrophoresis confirms the observation by Lasker et al. of eight chromosomes. The genes previously assigned to chromosome 1 in fact fall into two groups, one (including ADE1, SOR9, and CDCJO) is linked to the ribosomal DNA genes on a chromosome called R, whereas the others are found on chromosome 1. Chromosome R varies in electrophoretic mobility among strains, usually running equal to or faster than chromosome 1 but in rare cases running slower than chromosome 1. In strain 1012A, the decreased mobility of one homolog is associated with the very large majority of the rDNA genes being on that homolog; the second homolog, with only a few copies, migrates with chromosome 2. Linkage analysis by using spheroplast fusion confirms the gene assignments made by hybridiza-tion to blots of the electrophoretic karyotype. A newly cloned gene, LYS2, hybridizes to chromosome 1. The dimorphic, asexual yeast Candida albicans is one of the most important human fungal pathogens. In the last 10 years, significant advances in the study of the genetics of this organism have been made, including the demonstration that virtually all isolates are diploid (19), the development of parasexual genetics (4, 10), and the demonstration of DNA