Dec 3, 2014

Natural Variation in Preparation for Nutrient Depletion Reveals a Cost-Benefit Tradeoff

BioRxiv : the Preprint Server for Biology
Jue WangMichael Springer

Abstract

Maximizing growth and survival in the face of a complex, time-varying environment is a common problem for single-celled organisms in the wild. When offered two different sugars as carbon sources, microorganisms first consume the preferred sugar, then undergo a transient growth delay, the “diauxic lag”, while inducing genes to metabolize the less preferred sugar. This delay is commonly assumed to be an inevitable consequence of selection to maximize use of the preferred sugar. Contrary to this view, we found that many natural isolates of Saccharomyces cerevisiae display short or non-existent diauxic lags when grown in mixtures of glucose (preferred) and galactose. These strains induce galactose-utilization (GAL) genes hours before glucose exhaustion, thereby “preparing” for the transition from glucose to galactose metabolism. The extent of preparation varies across strains, and seems to be determined by the steady-state response of GAL genes to mixtures of glucose and galactose rather than by induction kinetics. Although early GAL induction gives strains a competitive advantage once glucose runs out, it comes at a cost while glucose is still present. Costs and benefits correlate with the degree of preparation: strains with highe...Continue Reading

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Mentioned in this Paper

Microorganism
Galactose Measurement
Strategy
GLYR1
GAL-1
Genes
Saccharomyces cerevisiae allergenic extract
GALM gene
Complex (molecular entity)
Environment

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