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As an important measure in the research of yeast aging , the study of chronological lifespan sheds a light on the aging mechanism of both yeast and higher eukaryotes,and therefore has been calling a great deal of attention and enormous research efforts in elucidating its mechanisms. It has close relationship with the cAMP signaling pathway (the Ras/cAMP/PKA signal transduction pathway),Sch9 and the nutrients. Investigating the role of the cAMP signaling pathway and Sch9,together with the nutrients,in the regulation of budding yeast chronological lifespan,will not only intensifies our current understanding of chronological lifespan,but also aids the research of aging in higher eukaryotes.We created sch9△and ras2△(because of its core role in the Ras/cAMP/PKA pathway,),deleted MSN2,4,SOD2 and RIM15 individually in the two mutants and then examined the role of these proteins in the regulation of yeast chronological lifespan and heat resistance under different nutrient conditions.To understand the role of Ras2 and Sch9 in the process,the chronological lifespan and heat stress resistance assay of ras2△and sch9△pregrown in SCglucose and SCglycerol were studied. We found that the relationship yeast chronological lifespan has with the cAMP pathway is due to the carbon source while the regulation of heat stress resistance is not.Meanwhile,analysis of the chronological lifespan and stress resistance of the mutants(mutants with background of ras2△or sch9△,lack of RIM15,MSN2,4 or SOD2) progrown in SCglucose and SCglycerol suggests that Msn2,4 and Sod2 are involved in the regulation of Ras2 and Sch9 in chronological aging at different levels and indicates that there may be other elements needed for this. Additionally,besides Msn2,4,Sch9 affects the heat stress resistance by regulating Sod2 in some certain way.
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