Figure 3. Kinetics of Notch activation in response to increasing or decreasing exposure to CO₂.

A,B. N-GV/Gr21a.dsRed; UAS.GFP/+ flies were raised to eclosion and aged on dextrose food for four to seven days, then shifted to agar and exposed to 5–10% CO₂ for the indicated time periods. The nuclear GFP (green) and dsRed (magenta) fluorescence were visualized in whole mount antennae (coincident fluorescence appears white); note that some non-Gr21a expressing ORNs have accumulated GFP, presumably in response to other odorants (A). The depicted 72hr antenna was exposed to 7% CO2. All other images of CO₂ exposed antennae are from flies exposed to 5% CO₂. The graph (B) depicts box plots of the % Gr21a.dsRed cells that expressed GFP at the indicated times of exposure and % CO₂ (in parentheses). Here and in all box plots presented below, the horizontal line in the box is the median of the entire data set; the lines at the top and bottom of the box are the medians of the higher and lower 50% respectively; the whiskers at the top and bottom are the maximum and minimum values excluding the outliers (dots), which are more than 3/2 times the upper quartile or less than 3/2 times the lower quartile. The Mann-Whitney test was applied to data from pairs of time points. ns: not significant; *: P≤ 0.05; **: P≤ 0.01; ***: P≤ 0.001. The number of samples analyzed was: 0hrs, 17; 6hrs (5%), 12; 6hrs (10%), 19; 12hrs (5%), 11; 18hrs (5%), 14; 24hrs (5%), 18; 24hrs (7%), 19; 72hrs (7%), 13.

C. As in A, except that N-GV UAS.dGFP/+ flies were used, and exposed to 5% CO₂ on dextrose food for 3 days. Flies were removed from CO₂ for the indicated lengths of time, and the Notch response assayed by quantitating dGFP accumulation in the V glomerulus. The graph depicts box plots of the integrated density of fluorescence in V. The number of samples analyzed was: 0 days, 32; 1day, 28; 2 days, 28; 3 days, 23; 4 days, 26; no CO₂, 17.