How to survive within a yeast colony

Abstract

Yeast colonies growing on solid medium begin at a particular point in their development to produce volatile ammonia and to alkalize their surroundings.¹ Ammonia serves as a long-range signal between neighboring colonies and was shown to influence various aspects of colony biology including metabolic reprogramming and differentiation. In a recent paper we presented the impact of deleting of key stress defense enzymes on ammonia signaling and colony development. New findings suggest that it is not stress defense, but rather proper development guided by ammonia signaling and related metabolic changes that are important factors in the long-term survival of a colony cell population.

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Acknowledgements

This work was supported by Grant Agency of the Czech Republic (204/08/0718), by Ministry of Education (LC531, MSM0021620858 and AV0Z50200510) and by the Howard Hughes Medical Institute (International Research Award 55005623 to Z.P.).

Figures and Tables

Figure 1 Different factors are important for survival in liquid cultures and in colonies. (A) Survival in liquid culture is dependent on stress defense. Stress-defense-deficient population dies rapidly unless stress-resistant mutants appear and overgrow the dying population. (B) Survival in a colony is dependent on metabolic adaptation of the population. Colony cell population switches metabolism as a result of ammonia signal which enables survival of cells at colony margin. Cells in colony centre die and provide nutrients for the benefit of cells at the colony margin. Development of a colony incapable of ammonia signaling is not orchestrated, cells are not able to activate their alternative metabolism and consequently cell death is spread throughout the whole colony. Color of the agar-medium indicates pH changes during colony development: yellow, pH below 6.5; violet, pH above 6.5.

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