Fig 2. IR76b is required for the polyamine odor response of IR41a OSNs.

(A) In vivo imaging setup illustration (top). Illustrative confocal image showing the IR41a and IR76b OSN innervating glomeruli pattern (bottom). VC5 is the glomerulus innervated by the polyamine-responding IR41a sensory neurons. (B–D) In vivo calcium imaging of IR41-Gal4;UAS-GCaMP6f flies stimulated with water and 6, 8, and 10 ppm putrescine, respectively. Please note that that based on PID measurements, 10 ppm most closely represented the 1 mM concentration used in behavioral experiments due to the technical differences of odor application. (B) Representative pseudocolor images showing the response to water and increasing doses of putrescine, respectively. (C) Quantification of peak ΔF responses of the VC5 glomerulus (n = 9). (D) Average activity trace of VC5 glomerulus upon polyamine stimulation in %ΔF/F. (E) Prestimulation fluorescence micrograph showing IR76b positive glomeruli. (F–H) In vivo calcium imaging of IR76b-Gal4;UAS-GCaMP6f flies stimulated with water and 6, 8, and 10 ppm putrescine, respectively. (F) Representative pseudocolor images showing the response to increasing doses of putrescine. (G) Quantification of peak ΔF responses of the VC5 glomerulus (n = 6). (H) Average activity trace of VC5 glomerulus in %ΔF/F. (I–K) In vivo calcium imaging of IR76b-Gal4,UAS-GCaMP6f;IR76b¹ and heterozygous control flies stimulated with water and 10 ppm putrescine, respectively. (I) Representative pseudocolor images showing the response in the VC5 glomerulus. (J) Quantification of peak ΔF responses in mutant and control flies. Boxes show median and upper/lower quartiles, and whiskers show minimum/maximum values. ***p < 0.001 by unpaired t test with Welch correction (n = 6). (K) Average activity trace of VC5 glomerulus. (D, H, K) The gray column represents the 0.5 second stimulation period. Dark colored line is the average response and the light shade is the standard error of the mean (SEM).