High-Frequency Switching of Colony Morphology in Candida albicans

Abstract

The pathogenic yeast Candida albicans switches heritably and at high frequency between at least seven general phenotypes identified by colony morphology on agar. Spontaneous conversion from the original smooth to variant phenotypes (star, ring, irregular wrinkle, hat, stipple, and fuzzy) occurs at a combined frequency of 1.4 X 10(-4), but is increased 200 times by a low dose of ultraviolet light that kills less than 10 percent of the cells. After the initial conversion, cells switch spontaneously to other phenotypes at a combined frequency of 2 X 10(-2). Switching is therefore heritable, but also reversible at high frequency. The genetic basis of this newly discovered process and its possible role in Candida pathogenesis are considered.

Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice

“…neoformans change their phenotypes when they are subcultured repeatedly or passaged in vivo [11][12][13][14][15][16]. C. albicans spontaneously switches the morphology of its colonies into at least seven general phenotypes [16].…”

“…In this regard, clinically important fungi such as Candida albicans and Cryptococcus neoformans are known to change their phenotype after repeated subcultures or in-vivo passages [11][12][13][14][15][16]. This process is thought to allow some fungi to escape eradication by the host immune system [11,[13][14][15].…”

Fine-Resolution Physical Mapping of Genomic Diversity in Candida albicans

“…The electrophoretic karyotype of 1006 is the one most frequently found in clinical isolates. WO-1 (Slutsky et al 1985) was shown by Chu et al (1993) to have several reciprocal translocations, including one involving chromosome 7. Iwaguchi et al (1990) selected ten strains showing chromosome length polymorphism (CLP) from 50 clinical strains in Nagoya, Japan.…”

Phenotypic Switching of Cryptococcus neoformans and Cryptococcus gattii

“…For fungi phenotypic switching is defined as the reversible change manifested as altered colony morphology at a rate higher than the somatic mutation rate. Phenotypic switching has been reported first in Candida over 20 years ago [2,3] and the molecular mechanism has been studied extensively [4,5]. In Candida phenotypic switching controls mating and has also been proposed to contribute to virulence [6].…”