Figure 8. Homeostatic responses to strong stimuli, but not micro-homeostasis, require DAF-16.
(A) Left: the fraction of quiescence of wild-type animals and daf-16 mutants during L4leth (shaded area). Plots depict mean ± s.e.m, the numbers of animals assayed are denoted in parentheses. Right: pairwise bout correlations shown with a plot of binned bouts (see Figure 2A for details). Pairwise correlations were reduced in the mutant, although less so than in npr-1 mutants (p < 0.05). All correlations are given with 95% confidence intervals and error bars depict ±s.e.m. The number of bouts in each case is denoted in parentheses. (B) A posture-based analysis of responses of L4int and L4leth daf-16 mutants to strong stimuli (15 s, 1 kHz vibrations): the fraction of forward locomotion, backward locomotion, dwelling, and quiescence before, during, and after the stimulus. (C) Left: frame subtraction based analyses of responses of L4leth daf-16 mutants to weak stimuli (15 s, 20 mW/cm2, blue light). Inset: the response of daf-16 mutants during L4leth on a semi-log scale. Middle: the fraction of quiescence during 1 min intervals centered at the times of the peak and trough of the L4leth responses, as well as for their respective pre-stimulus baselines. All stimuli were initiated at t = 0. N = 50–60 animals. Plots and bars depict mean ± s.e.m, asterisks denote p < 0.001. Right: a posture-based analysis of bout dynamics of daf-16 mutants following a weak stimulus. Plots depict mean ± s.e.m, smoothed using a 30 s running window average. N = 12 animals. The compensatory enhancement of quiescence bouts shortly after the stimulus, as assayed by both methods, was similar to wild-type. (D) The mean baseline fractions of quiescence of daf-16 mutants in undisturbed animals and in the presence of weak and strong stimuli. In contrast to wild-type, baseline quiescence fraction was indistinguishable between the different conditions. Expression of daf-16 in neurons, but not in body-wall muscles, restored the homeostatic response of daf-16 mutants to strong mechanical stimuli. Error bar depicts ±s.e.m. The number of stimuli assayed is noted in parentheses for each condition.