Natural heterozygosity in Candida albicans

Area of Science:

• Microbiology
• Genetics
• Mycology

Background:

• Candida albicans is an opportunistic fungal pathogen.
• Understanding its genetic structure is crucial for clinical and epidemiological studies.

Purpose of the Study:

• To investigate the genetic basis of auxotrophy in Candida albicans.
• To explore the ploidy and heterozygosity of C. albicans clinical isolates.

Main Methods:

• Subjecting 16 Candida albicans clinical isolates to ultraviolet radiation.
• Testing UV-surviving isolates for auxotrophic mutations.
• Analyzing auxotroph spectra to infer genetic states.

Main Results:

• Six isolates showed biased auxotroph spectra, yielding specific auxotrophs (methionine, isoleucine-valine, adenine, lysine).
• Evidence suggests auxotrophs arise from heterozygous states.
• Most isolates yielded few or no auxotrophs, indicating diploidy, though aneuploidy cannot be excluded.

Conclusions:

• Candida albicans is likely diploid with frequent heterozygosity.
• Heterozygosity may serve as a useful marker in epidemiological investigations.
• The study provides a rationale for the common occurrence of heterozygosity in C. albicans.