The importance of the genetic background and the nitrogen source in yeast aging

JENNIFER VALENCIA GUILLEN; MARIANA BERMUDEZ MORETTI; FACUNDO GULIAS; SEBASTIAN MUÑOZ; CORREA GARCIA SUSANA

CABA

Congreso; Reunión Conjunta de Sociedades de Biociencias: LIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2017

Aging is a complex process accompanied by progressive, deleterious changes that eventually lead to death. Caloric restriction (CR) is one of the best non-genetic means that can extend lifespan in almost every organism studied. CR consists in the mere reduction of caloric intake without malnutrition. The aim of this work was to analyse if the effect of CR, a well-known intervention to delay aging, is influenced by the yeast genetic background and by the nitrogen source used. Chronological lifespan (CLS) was measured using the colony forming unit spot assay in yeast cells derived from two different genetic backgrounds grown in 0.5% (CR condition) or 2% (control condition) glucose as carbon source and in proline (10 mM) or ammonium sulphate (0.5 %) as nitrogen source. We found that CR had opposite effect on CLS of the BY4741 and 23344c background strains (auxotrophic and prototrophic strains, respectively) grown on ammonium sulphate. In BY4741 cells grown in 0.5% glucose lifespan extension was observed whereas 23344c cells were more long lived in 2% than in 0.5% glucose. When proline was used as nitrogen source, aging of both strains was delayed and was similar in both carbon conditions. Tolerance to oxidative stress was determined during aging, being BY4741 cells grown on CR condition more resistant independently of the nitrogen source. On the other hand, viability, stress resistance, cellular respiratory activity, autophagy and the activity of the UPR pathway were determined in cells during the first 72 hours of growth before cells were submitted to the aging process. Several differences and similarities were found in cells of both genetic backgrounds grown in those growth conditions. Findings presented here demonstrate how profoundly genetic background and nitrogen source can modify lifespan extension of cells. Moreover, results obtained during the first 72 hours of growth will contribute to establish relationships between the way cells live and their longevity.