Specific biomarkers for stochastic division patterns and starvation-induced quiescence under limited glucose levels in fission yeast

Glucose as a source of energy is centrally important to our understanding of life. We investigated the cell division-quiescence behavior of the fission yeast Schizosaccharomyces pombe under a wide range of glucose concentrations (0-111 mM). The mode of S. pombe cell division under a microfluidic perfusion system was surprisingly normal under highly diluted glucose concentrations (5.6 mM, 1/20 of the standard medium, within human blood sugar levels). Division became stochastic, accompanied by a curious division-timing inheritance, in 2.2-4.4 mM glucose. A critical transition from division to quiescence occurred within a narrow range of concentrations (2.2-1.7 mM). Under starvation (1.1 mM) conditions, cells were mostly quiescent and only a small population of cells divided. Under fasting (0 mM) conditions, division was immediately arrested with a short chronological lifespan (16 h). When cells were first glucose starved prior to fasting, they possessed a substantially extended lifespan (～14 days). We employed a quantitative metabolomic approach for S. pombe cell extracts, and identified specific metabolites (e.g. biotin, trehalose, ergothioneine, S-adenosyl methionine and CDP-choline), which increased or decreased at different glucose concentrations, whereas nucleotide triphosphates, such as ATP, maintained high concentrations even under starvation. Under starvation, the level of S-adenosyl methionine increased sharply, accompanied by an increase in methylated amino acids and nucleotides. Under fasting, cells rapidly lost antioxidant and energy compounds, such as glutathione and ATP, but, in fasting cells after starvation, these and other metabolites ensuring longevity remained abundant. Glucose-starved cells became resistant to 40 mM H(2)O(2) as a result of the accumulation of antioxidant compounds.