(A) Time profiles of mean forward locomotion speed. Shadings show SEM. Dashed lines indicate onset of O2 downshift. The horizontal bar indicates time axis. (B–E) Boxplots of forward locomotion speed (B, C) measured during a 4 min interval at 21% oxygen and (C, D) of the percent change in response to the oxygen downshift. Changes were calculated by subtracting the means of 60 s intervals post-downshift from the means of 60 s pre-downshift intervals divided by the means of the interval pre-downshift. Genotypes indicate transgenic rescue using cell specific promoters (pDVA, pAVK). Boxplots display trial-median, interquartile range and 5–95 percentile whiskers. Asterisks on top of box plots indicate significance levels compared to wild type N2 and asterisks on top of brackets indicate significance levels for comparisons with the respective mutant or selected genotypes, using one-way-ANOVA with Sidak’s correction for multiple comparisons (****p≤0.0001, ***0.0001<p≤0.001, **0.001<p≤0.01, *0.01<p≤0.05, ns p>0.05). Number of experiments (each ~25 animals): (B, D) N2 n = 36, flp-1 n = 29, AVK- n = 21, nlp-12 n = 21, DVA- n = 13, flp-1;nlp-12 n = 12 and AVK-;DVA- n = 10. (C, E) N2 n = 10, nlp-12 n = 6, pDVA: nlp-12 rescue under Pnlp-12 n = 11, flp-1 n = 11, pAVK: flp-1 rescue under Pflp-1 fragment n = 9, N2 n = 11, flp-1;nlp-12 n = 11, pAVK;pDVA: flp-1 rescue under Pflp-1 fragment & nlp-12 rescue under Pnlp-12 n = 11.