Research Paper Volume 8, Issue 4 pp 777—795

Figure 3. Specific stress-responsive pathways fail to respond to stress with advancing age. To examine the effect of aging on the ability of specific stress-responsive pathways to become activated, we used fluorescent reporter strains and exposed worms to stress at increasing ages. The Pgst-4::GFP (D,E), Pgcs-1::GFP (F,G) and Phsp-6::GFP (B) reporter strains showed a decreased ability to respond to stress with increasing age such that by day 10 of adulthood there was no induction in response to stress. The Psod-3::GFP (I) reporter strain also failed to respond to stress on day 10 of adulthood. In contrast, the Phsp-16.2::GFP (A), Phsp-4::GFP (C), and Pnhr-57::GFP (H) reporter strains all maintained their ability to respond to stress until day 10 of adulthood. (J) Nuclear localization of DAF-16 could be induced by heat stress (35°C, 2 hours), anoxia (24 hours) and oxidative stress (4 mM PQ, 2 days) at all ages. Both bacterial pathogen exposure (P. aeruginosa) and starvation (2 days) showed a decreased ability to cause nuclear localization of DAF-16 with increasing age. Error bars indicate SEM. *p<0.05, **p<0.01, ***p<0.001.