Present address: Research Institute of Molecular Pathology, Institute of Molecular Biotechnology, Vienna, Austria.
Plasticity of death rates in stationary phase in Saccharomyces cerevisiae
Article first published online: 28 NOV 2008
© 2009 The Authors. Journal compilation © Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland 2009
Volume 8, Issue 1, pages 36–44, February 2009
How to Cite
Minois, N., Lagona, F., Frajnt, M. and Vaupel, J. W. (2009), Plasticity of death rates in stationary phase in Saccharomyces cerevisiae. Aging Cell, 8: 36–44. doi: 10.1111/j.1474-9726.2008.00446.x
- Issue published online: 28 JAN 2009
- Article first published online: 28 NOV 2008
- Accepted for publication 14 November 2008
- death rates;
- Saccharomyces cerevisiae;
- stationary phase
For the species that have been most carefully studied, mortality rises with age and then plateaus or declines at advanced ages, except for yeast. Remarkably, mortality for yeast can rise, fall and rise again. In the present study we investigated (i) if this complicated shape could be modulated by environmental conditions by measuring mortality with different food media and temperature; (ii) if it is triggered by biological heterogeneity by measuring mortality in stationary phase in populations fractionated into subpopulations of young, virgin cells, and replicatively older, non-virgin cells. We also discussed the results of a staining method to measure viability instead of measuring the number of cells able to exit stationary phase and form a colony. We showed that different shapes of age-specific death rates were observed and that their appearance depended on the environmental conditions. Furthermore, biological heterogeneity explained the shapes of mortality with homogeneous populations of young, virgin cells exhibiting a simple shape of mortality in conditions under which more heterogeneous populations of older cells or unfractionated populations displayed complicated death rates. Finally, the staining method suggested that cells lost the capacity to exit stationary phase and to divide long before they died in stationary phase. These results explain a phenomenon that was puzzling because it appeared to reflect a radical departure from mortality patterns observed for other species.