Research Paper Volume 8, Issue 4 pp 777—795

Figure 2. Stress-responsive reporters are not activated with increasing age. To determine whether different stress response pathways are activated with increasing age, we examined fluorescence in stress-responsive reporter strains at day 1, day 6 and day 10. None of unfolded protein response reporter strains showed increased activity with age (A-C). The two reporters for the SKN-1 mediated oxidative stress response both showed decreased fluorescence with age (D,E). The hypoxia reporter also showed no increase with age (F). The DAF-16 reporter exhibited increased expression at day 6 (G) but not increased activation as measured by nuclear localization (H,I). Finally, the SOD-3 reporter showed increased fluorescence at both day 6 and 10 (J). This increase appeared to be due to a change in expression pattern with increased expression around the vulva (K). These results suggest that any increase in internal stress that occurs with increasing age is insufficient to activate these stress-responsive pathways and or that the stress-responsive lose their ability to respond with age. Note that the mild increase in fluorescence in Phsp-16.2::GFP and Pnhr-57::GFP worms is due to autofluorescence. Error bars indicate SEM. ns = not significant. *p<0.05, **p<0.01, ***p<0.001.