GENOMIC HETEROGENEITY IN THE YEAST CANDIDA-PARAPSILOSIS

Candida parapsilosis shows a wide intraspecies variation in chromosome /homolog size distribution. As a prerequisite for delineating modes of transmission, we have undertaken an analysis of genetic variation at different levels. In the present study we have observed that a majorit y of isolates display similar electrophoretic karyotype patterns consi stent for the species, with variations in the smaller group of chromos omes. In two strains we observed phenotypic ''switching''; one of thes e also exhibited a mixed karyotypic subpopulation. In contrast, a few isolates displayed a greater degree of chromosome/homolog size variati on. We also observed, through randomly amplified polymorphic DNA (RAPD ) analysis, results consistent with those of pulsed-field electrophore sis. Isolates displaying a high degree of chromosome/homolog variation also displayed a high degree of variation in genomic ''fingerprints'' . Polymorphisms, although present, were much reduced in the majority o f isolates. These parallel observations suggest a common underlying me chanism. Our results are consistent with the hypothesis that chromosom e-sized variations in C parapsilosis are due to random genetic events. A similar mechanism has been hypothesized for the taxonomically relat ed yeast Candida albicans.