AN INCREASE IN SWITCHING FREQUENCY CORRELATES WITH AN INCREASE IN RECOMBINATION OF THE RIBOSOMAL CHROMOSOMES OF CANDIDA-ALBICANS STRAIN 3153A

When cells of Candida albicans strain 3153A are treated with a low dose of ultraviolet irradiation, they switch at high frequency (10(-2)) between a number of switch phenotypes discriminated by colony morphology. Clones from switching lineages exhibit continuous reorganization of their ribosomal chromosomes (R chromosomes), while clones from lineages maintaining the original smooth phenotype exhibit no reorganization. R chromosome reorganization results in decreases as well as increases in size of the chromosomes. but changes are not reciprocal between R chromosome homologues.