Fig. 2
From: Single olfactory receptors set odor detection thresholds
TAAR glomeruli are the most sensitive amine receptors in the dorsal olfactory bulb. a Confocal image of the dorsal olfactory bulbs from a compound heterozygous OMP-GCaMP3/TAAR3-YFP/TAAR4-RFP mouse. Anterior is up. b Schematic of set-up for wide-field in vivo calcium imaging in head-fixed, awake mice. Odors are delivered using a flow dilution olfactometer, and mice receive water rewards after odor trials. c Wide-field fluorescence image of an olfactory bulb showing resting GCaMP fluorescence (cyan) and response in a single glomerulus to trimethylamine (warm colors) in an awake mouse. Circle shows the general region of the olfactory bulb imaged at higher magnification in all experiments. d Higher-magnification imaging of odor-evoked activity from TAAR glomeruli in the dorsal olfactory bulbs. (Left) Resting fluorescence shows genetically tagged TAAR3 (green) and TAAR4 (magenta) glomeruli in three different mice. (Right) Odor-evoked GCaMP responses to amines. Medial is to the right. Locations of tagged glomeruli are marked with colored arrows. Locations of TAAR5 glomeruli, based on response profile, are marked with white arrows. e Dose–response curves from individual TAAR glomeruli to isopentylamine (top), phenylethylamine (middle), and trimethylamine (bottom). Plots show mean +/− SE with a shaded 95% confidence interval. Data were fitted to a Hill function. Isopentylamine: TAAR3 EC50 = 4.1 × 10−10 M (95% CI = 1.3–9.9 × 10−10 M); TAAR4 EC50 = 9.9 × 10−9 M (95% CI = 6.9–14 × 10−9 M). Phenylethylamine: TAAR4 EC50 = 1.4 × 10−11 M (95% CI = 1.5–2.4 × 10−11 M); TAAR3 EC50 = 1.9 × 10−10 M (95% CI = 1.0–1.8 × 10−10 M). Trimethylamine: TAAR5 EC50 = 3.1 × 10−8 M (95% CI 1.7–7.6 × 10−8 M); TAAR4 EC50 = 4.7 × 10−7 M (95% CI 1.2–21.0 × 10−7 M); TAAR3 EC50 = 7.9 × 10−7 M (95% CI 2.9–12.8 × 10−7 M). Scale bar 500 μm in a, c, 200 μm in d
