Evolution in Candida albicans populations during a single passage through a mouse host

Area of Science:

• Microbiology
• Genetics
• Evolutionary Biology

Background:

• Mechanisms generating genotypic and phenotypic variation in eukaryotic pathogens during host growth are poorly understood.
• Candida albicans is an opportunistic human fungal pathogen with a significant impact on public health.

Purpose of the Study:

• To investigate the genomewide genetic and phenotypic evolution of Candida albicans during host passage (in vivo) versus laboratory culture (in vitro).
• To compare the rates and patterns of genetic variation, including loss of heterozygosity (LOH) and chromosome rearrangements, between in vivo and in vitro growth conditions.

Main Methods:

• Passaging Candida albicans populations through a mouse host (in vivo) and in liquid culture (in vitro).
• Analyzing genomewide genetic variation, including chromosome-level changes and LOH.
• Assessing phenotypic variation through colony morphology and growth characteristics.

Main Results:

• Slower population growth rates were observed in vivo compared to in vitro.
• Higher rates of chromosome-level genetic variation and genomic rearrangements occurred in populations passaged in vivo.
• In vivo populations exhibited a positive correlation between genetic alterations and phenotypic variation (colony morphology, growth), which was absent in vitro.

Conclusions:

• Host passage significantly increases genomic and phenotypic variation in Candida albicans compared to in vitro growth.
• Distinct patterns of genomic rearrangements in vivo suggest host environment influences evolutionary dynamics.
• These findings highlight the role of population growth dynamics and genomic instability in maintaining the commensal and opportunistic lifestyle of C. albicans.