"White-opaque transition": a second high-frequency switching system in Candida albicans

Area of Science:

• Microbiology
• Yeast Genetics
• Cell Biology

Background:

• Pathogenic strains of Candida albicans possess a high-frequency switching system.
• The dimorphic yeast Candida albicans is a significant human pathogen.

Purpose of the Study:

• To characterize a second high-frequency switching system in Candida albicans.
• To investigate the white-opaque transition in strain WO-1.

Main Methods:

• Phenotypic analysis of colony morphology on agar at 25°C.
• Microscopic examination of cell shape, size, and budding patterns.
• Assessment of generation time, temperature sensitivity, and hyphal formation capacity.

Main Results:

• Identified heritable, reversible high-frequency switching (approx. 10^-2) in strain WO-1.
• Characterized two main phenotypes: white colonies (similar to standard strains) and opaque colonies (larger, flatter, grey).
• Observed significant differences in cell morphology, generation time, temperature sensitivity, and hyphal formation between white and opaque cells, despite similar DNA content and nuclear status.

Conclusions:

• The white-opaque transition in Candida albicans is based on fundamental differences in cellular morphology.
• This switching system affects key cellular behaviors, including growth rate, stress tolerance, and virulence potential.
• Further investigation into the molecular mechanisms underlying this high-frequency switching is warranted.