FIGURE 2: Opposite effects of salicylate and cAMP signalling pathway on yeast growth reactivation. (A) Growth reactivation delay of chronologically aged yeast cells induced by salicylate. wt cells arrested into stationary phase for 22 days were inoculated into fresh medium in the presence of different concentrations of salicylic acid. The cellular density was measured as OD_600nm after 17 hours (black) obtaining the salicylate dose-response curves shown in figure. (B) Early growth reactivation elicited by cAMP in chronologically aged yeast cells. A 18 days-aged cyr1Dpde2Dmsn2Dmsn4D mutant strain was inoculated into fresh medium supplied (red) or not (black) with 3 mM cAMP. The Log₁₀ of OD_600nm values monitored during mid-log phase were plotted versus time (hours) and fitted with linear regression curves. As the curves were parallel, the time difference at a same mid-log cell density is a convenient estimation of the difference between lag times before growth in the two conditions. cAMP pushed cells to reactivate growth ~1.15 hours earlier than control cells, as shown graphically.