There is also evidence in S. cerevisiae for a functional link between the pheromone response MAP kinase pathway and the MAP kinase pathway involved in cell wall integrity, as S. cerevisiae strains lacking the MAP kinase Slt2 die after APO866 exposure to pheromone [18]. Transcription factors present at the mating locus are additional regulators of mating in fungi such as Cryptococcus neoformans and

C. albicans [19, 20]. The MAT1-1-1 and MAT1-2-1 transcription factors of H. capsulatum have previously been shown to be transcriptionally responsive to conditioned media enriched for pheromone [2], indicating that these transcription factors play a role in the mating process of H. capsulatum as well. We generated a laboratory strain, UC1, which was capable of forming empty cleistothecia when paired with a fresh clinical strain of opposite mating type. Unlike other DAPT strains of H. capsulatum, UC1 did not lose the ability to

form cleistothecia over time. We hypothesized that understanding how UC1 gained the ability to form cleistothecia would explain how H. capsulatum strains lose the ability to mate over time. We sought PRIMA-1MET molecular weight to determine how UC1 gained the ability to form cleistothecia, and then determined that UC1 could be used to identify molecular events contributing to cleistothecia production in H. capsulatum. H. capsulatum is a dimorphic fungus, growing in the yeast phase at 37°C and in mycelial phase at room temperature. Because mating occurs in the mycelial phase, these studies were performed using organisms growing in the mycelial phase. The UC1 strain was originally generated by Agrobacterium tumefaciens-mediated transformation and integration of the T-DNA region from the vector pCB301-GFP-HYG into the strain G217B [21]. The strain G217B was isolated in 1973 [22], has been extensively

Thalidomide passaged in the laboratory, and is itself unable to form cleistothecia. The UC1 strain, derived by transformation of the G217B strain, is thought to have gained the ability to produce empty cleistothecia due to a combination of the transformation procedure itself, and the site of T-DNA integration. We used the UC1 strain to study cleistothecia formation by searching for differences between UC1 and its parent G217B, and we determined that the H. capsulatum homolog of protein kinase C (PKC1) plays a role in cleistothecia formation. Results Characterization of cleistothecia-like structures formed by UC1 and UH3 The strain UC1 formed cleistothecia when paired with the fresh clinical strain UH3. Cleistothecia were visible to the naked eye at the periphery of the colony when mycelial scrapings of each strain were co-incubated on A-YEM agarose at room temperature for one month. At 400-500×, the net-like hyphae forming the cleistothecia were visible, as were characteristic coiling hyphae radiating from the cleistothecia (Figure 1A, Figure 2E).