A Putative Bet-Hedging Strategy Buffers Budding Yeast against Environmental Instability.

Area of Science:

• Cellular biology
• Metabolic strategies
• Yeast genetics

Background:

• Cells require resources from dynamic environments for growth and division.
• Budding yeast employs metabolic strategies like fermentation (speed) and respiration (yield) for ATP production.
• Environmental unpredictability necessitates adaptive cellular mechanisms.

Purpose of the Study:

• To investigate the variability in yeast's metabolic switching from fermentation to respiration upon glucose withdrawal.
• To characterize distinct subpopulations of glucose-starved yeast cells.
• To explore the evolutionary implications of these subpopulations, specifically bet hedging.

Main Methods:

• Inducing glucose starvation in exponentially growing budding yeast cultures.
• Observing and quantifying cell subpopulations: recoverers and arresters.
• Assessing the heritability of these states and their fitness in different glucose conditions.
• Analyzing natural variation in subpopulation frequencies across wild yeast strains.

Main Results:

• Two distinct subpopulations, 'recoverers' and 'arresters,' emerged upon glucose withdrawal.
• 'Recoverers' rapidly adapt and resume growth, while 'arresters' enter a shock state with cellular deformations.
• These states are heritable, with 'arresters' showing faster growth in high glucose and 'recoverers' having an advantage during carbon source shifts.
• Natural variation in the frequency of these states exists across wild yeast strains.

Conclusions:

• Budding yeast utilizes a bet-hedging strategy, involving distinct heritable cell states, to cope with environmental unpredictability.
• This phenotypic variation provides a fitness advantage in fluctuating environments.
• The observed variation suggests an evolved mechanism for survival and adaptation in dynamic ecological niches.