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Profile - Stavros Gonidakis
Stavros Gonidakis
Contact Information
E-mail: gonidaki@usc.edu
Mail Code: 0371
Started at USC: Fall 2004
Education:
2004 – present
Ph.D. Candidate , Integrative & Evolutionary Biology
University of Southern California, Los Angeles
2001 – 2004
B.A., Biochemistry
University of Cambridge, UK
Faculty Advisor(s):
Dr. Valter Longo, Gerontology
Research Topics: aging, Saccharomyces cerevisiae (yeast)
Research Abstract:
Nothing is for ever. Living organisms experience the inescapable fate linked to their existence as an increasing probability of death over time. Molecular biogerontology, the study of the ageing process at a molecular level, began in the early ‘80’s with the remarkable observation that the inactivation of a single gene of the roundworm Caenorhabditis elegans significantly extends the organism’s lifespan. More than two decades of work in three other model systems (yeast, fruitfly and mouse) have revealed the existence of evolutionarily conserved signaling pathways modulating growth, metabolism and ageing in response to environmental cues.
My Ph.D. advisor, Valter D. Longo, is largely responsible for the introduction of the unicellular eukaryote Saccharomyces cerevisiae to the world of biogerontology. The wealth of genetic and biochemical techniques available for the study of this organism, as well as its short mean lifespan (approximately 7 days in the commonly used nutrient medium) render it an ideal model system for the study of ageing. Our lab has identified that the deletion of the genes Ras2 and Sch9, greatly extends the lifespan of the organism. Other phenotypes often associated with increased lifespan in the yeast and the other model organisms mentioned above include slow growth, reduced fertility and increased resistance to thermal and oxidative stress.
The research direction I’ve been following involves the characterization of cell-environment interactions during the ageing of a yeast culture. More specifically, I’m testing the hypothesis that specific components of the liquid medium in which a yeast population is maintained are partly responsible for the population’s aging. My hypothesis was formulated based on the following observations: Yeast cells inoculated into fresh nutrient medium divide until reaching saturation and then enter stationary phase. The pH of the medium at the onset of stationary phase is 3-3.5. The population’s mean lifespan is approximately 7 days under these conditions. Incubation of the ageing population in sterile distilled water or adjustment of the pH to a neutral value extend the population’s mean lifespan by approximately 100%. These observations are consistent with the existence of specific substances in the medium active at low pH that contribute to the progressive loss of viability observed in the population.
My experimental strategy is based on the use of filtering devices for the separation of substances present in the nutrient medium according to their molecular weight. Incubation of a yeast population in a medium from which the putative ageing factors have been removed should result in an increase in the population’s lifespan.
Another exciting prospect I’m willing to pursue is the identification of the cell surface receptors and intracellular signaling pathways that transduce the presence of the ageing factors to the cells’ interior. It would also be revealing to examine any overlap between these signaling pathways and the ones already described by our lab as modulators of the lifespan of yeast.
Although the microorganism used by bakers to make bread appears an unlikely candidate for the study of ageing, it has provided us with a few valuable lessons about the physiology of ageing which have generated hypotheses testable in higher eukaryotes. I’m hoping that my research will provide another such entry point to gene-environment interactions affecting an organism’s aging rate.
Recent Publications:
Gonidakis S. and Longo V.D. (2008) Oxidative stress and aging in the budding yeast Saccharomyces cerevisiae. In Miwa S., Beckman K.B., Muller F.L. (eds.), Oxidative stress in aging, from model systems to human diseases, Humana press
Gonidakis S. and Longo V.D. (2008) Programmed longevity and programmed aging theories. In Bengston V., Silverstein M., Putney N., Gans D. (eds.), Handbook of theories of aging, Second edition, Elsevier
CV: Click to view