Differentiation in yeast colonies: Ammonia regulated localisation of the cell death.
Libuse Vachova (1), Zdena Palkova (2)
(1) Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic; (2) Department of Genetics and Microbiology, Charles University, Vinicna 5, 128 44 Prague 2, Czech Republic
In metazoa, programmed cell death (PCD), including apoptosis and apoptosis-like PCD, is essential for development of differentiated tissues and for removal of aged or impaired cells. Such cell removal must avoid release of toxic cellular components that could injure tightly attached adjacent cells in multicellular organism. Despite indications that at least some of the biochemical changes (e.g. phosphatidylserine relocalisation, DNA breaks, chromatin fragmentation and caspase activation) typical for mammalian PCDs exist in liquid yeast cultures, the PCD significance to simple unicellular organism is still questioned. Such doubts usually do not reflect the fact that microorganisms in nature exist predominantly within structured multicellular communities (in which cells are tightly attached one to each other) capable of differentiation, in which a profit of individual cells is subordinated to a profit of the population. We show that properly regulated PCD, its accurate timing and localisation, enables differentiation of Saccharomyces cerevisiae colonies that appears to be important for long-term survival of colony population (Vachova & Palkova, submitted, under revision, 2005). This work is supported by AV0Z50200510, LC531 and 525/05/0297.