Dimorphic yeast Yarrowia lipolytica shows phenotypic markers of apoptosis when exposed to hypoxia or treated with hydrogen peroxide.
Marek Mentel, Miroslava Baculíková, Gabriela Cellengová, Jordan Kolarov
Department of Biochemistry, Comenius University, Mlynska dolina CH-1, Bratislava, 842 15, Slovakia
Yarrowia lipolytica is strictly aerobic dimorphic yeast, which is extensively studied as an alternative eukaryotic microorganism to the most commonly used Saccharomyces cerevisiae and Schizosaccharomyces pombe. Exposure of Y. lipolytica grown at certain carbon sources to hypoxia led to the decrease of cell viability and lowered the clonogenicity. The decrease in the viability and the inability of the cells to divide was accompanied with the accumulation of reactive oxygen species. Furthermore, other phenotypic markers associated with apoptosis were observed such as nuclear fragmentation and exposure of phosphatidylserine at the outer layer of the cytoplasmic membrane. For S. cerevisiae it was shown, that apoptotic cell death can be triggered by various factors including H 2 O 2 and acetic acid. Aerobic cultivation of Y. lipolytica on sodium acetate as sole carbon source (pH 3) as well as treatment of the culture with H 2 O 2 resulted in the demonstration of apoptotic markers. These results assign Y. lipolytica to the yeast species, in which the phenotypic markers of apoptosis have already been described, such as S. cerevisiae or K. lactis. Considering that S. cerevisiae, K. lactis and Y. lipolytica practically cover the whole range of the subphylum Hemiascomycetes it could be assumed, that the molecular machinery performing the basic steps of apoptosis is present in all hemiascomycetous yeast species.