New insights into the cell cycle profile of Paracoccidioides brasiliensis.

The present work focuses on the analysis of cell cycle progression of Paracoccidioides brasiliensis yeast cells under different environmental conditions. We optimized a flow cytometric technique for cell cycle profile analysis based on high resolution measurements of nuclear DNA. Exponentially growing cells in poor-defined or rich-complex nutritional environments showed an increased percentage of daughter cells in accordance with the fungus' multiple budding and high growth rate. During the stationary growth-phase cell cycle progression in rich-complex medium was characterized by an accumulation of cells with higher DNA content or pseudohyphae-like structures, whereas in poor-defined medium arrested cells mainly displayed two DNA contents. Furthermore, the fungicide benomyl induced an arrest of the cell cycle with accumulation of cells presenting high and varying DNA contents, consistent with this fungus' unique pattern of cellular division. Altogether, our findings seem to indicate that P. brasiliensis may possess alternative control mechanisms during cell growth to manage multiple budding and its multinucleate nature.