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Pathogenic yeasts
The image below is of pathogenic yeast Cryptococcus gattii. Cryptococcus gattii and Cryptococcus neoformans cause meningitis in healthy individuals and AIDS patients. The fungus grows in the body as yeasts with a thick capsule (brown). It is not known how these yeasts initiate infection. One theory suggests that in nature these cells mate sexually with yeasts of an opposite mating type. The process involves formation of thread-like hyphae (blue), which terminate in reproductive bodies called basidia (yellow) where sexual spores termed basidiospores (green) are formed. Basid-iospores are possible infectious units, which upon inhalation initiate infection by changing into yeasts. A sophisticated regulatory network controls this reproductive cycle. Mutations in a regulatory protein Ste12 cause significant loss of reproductive vigor and survival of the pathogen in the environment and in the animal model. Thus, mating pathways influence overall fitness of the fungus, and could be exploited as new targets for antifungal drugs or as new probes for characterization of fungal populations.
Credit: Ren P, Springer DJ, Behr MJ, Samsonoff WA, Chaturvedi S & Chaturvedi V. Additional Wadsworth Credits: S. Lehrman, S. Narasipura, A. Verschoor, and the Molecular Genetics Core.
The image appeared on the cover of the July 2006 issue of Eukaryotic Cell.
