Research Paper Volume 2, Issue 10 pp 709—726

Figure 6. Impact of growth signaling pathways and caloric restriction on chronological lifespan in budding yeast. Glucose and other nutrients signal growth through conserved Sch9p-, Tor1p- and Ras-dependent pathways that inhibit Rim15p and its induction of oxidative stresses defenses, leading to elevated O₂^- that cause oxidative damage and DNA replication stress. Acetic acid induces O₂^- by activating the same pathways. Caloric restriction attenuates signaling through these pathways and also induces H₂O₂ that activates SODs and reduces levels of O₂^- independently of Rim15p. In caloric restriction conditions, H₂O₂ that accumulates as a byproduct of increased SOD activity might stimulate SOD activity further by a self-amplifying mechanism.