Selection of
longlived mutants of S. cerevisiae.
Stefanie Jarolim (1), Gino Heeren (1), Peter Laun (1), Alena Pichova (2),
Breitenbach Michael (1)
(1) Department of Genetics, University of Salzburg, Hellbrunnerstrasse 3,
Salzburg, 5020, Austria (stefanie.jarolim@sbg.ac.at); (2) Inst. of
Microbiology, Czech Academy of Sciences, Prague, Czech Republic
The most important genetic avenue to analysis of the ageing process are long-lived mutants. This is because mutations in many different genes will cause a decrease in the overall fitness and therefore may also result in a shortened lifespan. This tells us nothing about the physiology that is specific to the ageing process. It has not been possible up to now to select directly for long-lived mutants in S. cerevisiae. This is because of the extreme scarcity of senescent cells in a yeast cell population and due to technical problems with physical separation of old and young cells. We are proposing here to generate a more complete set of long-lived mutants and to identify ageing relevant genes. We used a new mutant isolation and screening system based on strain K6001 (Bobola et al., Cell 84(5):699-709 (1996)). In the absence of galactose, mother cells maintain division and daughter cells cease to divide. The strain works since the essential gene CDC6 is deleted and replaced by a copy integrated under the HO promotor and one copy under the GAL1 promotor. If grown in glucose, the strain divides until the mother cells become senescent, then the population stops growing. The mothers can be followed throughout their lifespan without the experiment being overrun by progeny. This provides a tool for screening mutant strains for their average lifespan, which have been preselected for resistance to oxidants. Presently we are screening a large set of mutants resistant to oxidative stress.