Fig. 6
From: Single olfactory receptors set odor detection thresholds
Overexpression of a threshold-determining TAAR does not enhance behavioral sensitivity. a Top: summary of transgenic strategy showing the control gene-targeted TAAR4 locus and transgene. The M71 transgene was modified by inserting a 5× homeodomain enhancer (enh) upstream of the transcription start site and by replacing the M71-coding sequence with the TAAR4-coding sequence, an internal ribosome entry site (i), and a fluorophore (tauRFP). Bottom: Sections of the olfactory epithelium and whole mounts of the olfactory bulb (dorsal view) in TAAR4-RFP and transgenic overexpressing mice. Scale bar is 50 μm in upper panels and 800 μm in lower panels. b Dose–response curves of OSN responses to phenylethylamine. Peak inward current was measured from single labeled neurons from TAAR4-RFP (black) and TAAR4 transgenic (magenta) mice. T4-RFP EC50 = 5.1 × 10−13 M (95% CI = 3.0–8.3 × 10−13 M). 5×21-TAAR4Tg EC50 = 5.5 × 10−13 M (95% CI = 2.5–11.6 × 10−13 M). c No effect of transgene expression on phenylethylamine sensitivity. Psychometric curves showing behavioral sensitivity (C1/2) of TAAR4 overexpressing transgenic mice (magenta) and wild-type littermates (black) to phenylethylamine. wt C1/2 = 8.1 × 10−12 M (95% CI: 4.6–16.8 × 10−12 M), 5×21-TAAR4Tg C1/2 = 9.3 × 10−12 M (95% CI: 6.0–15.9 × 10−12 M). d Effective transgenic rescue. Psychometric curves showing C1/2 of ΔTAAR4 mice (red) and ΔTAAR4 mice with the TAAR4 transgene (cyan) littermates. Wild-type (black) pyschometric curve is replotted from c. ΔT4 C½ = 4.6 × 10−11 M (95% CI = 2.4–13.0 × 10−11 M), ΔT4; 5×21-TAAR4Tg C½ = 6.7 × 10−12 M (95% CI = 3.3–15.3 × 10−12 M). Plots show mean +/− SE with a shaded 95% confidence interval
