Wednesday, 6 May 2015

The critical glucose concentration for respiration-independent proliferation of fission yeast, Schizosaccharomyces pombe

Kojiro Takeda, Caroline Starzynski, Ayaka Mori and Mitsuhiro Yanagida

The authors use fission yeast (S. Pombe) as a model organism to explore the relationship between cell proliferation and energy availability. S. Pombe is a more natural model system to consider than budding yeast (S. Cerevisiae), for a number of reasons. It divides symmetrically into two equally-sized daughters upon division; loses the ability to proliferate when depleted of mtDNA; and is unable to use ethanol as a respiratory substrate, all of which are held in common with higher animals and plants, unlike S. Cerevisiae.

By sweeping the glucose concentration, the authors find that the proliferation rate of S. Pombe abruptly halts at ~0.04% glucose, presumably since an energy deficiency prevents further division. They inhibit OXPHOS (using antimycin A), to show that the proliferation rate diminished by ~25% at high glucose concentration, and the halt in proliferation occurs sooner at ~ 0.1% glucose. By studying the oxygen consumption rate, the authors show that reducing glucose concentration shifted S. Pombe from anaerobic to aerobic respiration. Combined, these data suggest that by inhibiting OXPHOS, S. Pombe is unable to upregulate aerobic respiration in response to diminishing glucose supply, and thus ceases to proliferate at a lower glucose concentration.

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