Figure 1: Isolation of TMT-responsive OR genes.

(a) Optical imaging in the olfactory bulb (OB). Dorsal views of the right OB are shown. To identify glomeruli that specifically responded to the fox odourant, TMT, glomerular activity was analysed by optical imaging. Activities are shown in rainbow colours. Diluted TMT solutions (0.1, 1, 10 and 50%) were presented to mice. A related odourant, 4MT (10 and 50%), that induces aversive responses was used to exclude any 4MT-responsive glomeruli that crossreact with TMT. Activation areas for TMT (red) and 4MT (green) in the dorsal OB are schematically shown on the right. A, anterior; P, posterior; M, medial; L, lateral. Scale bar, 500 μm. (b) Dose responsiveness of ORs to TMT. Eighteen OR gene clones selected from the two screened sets were individually introduced into HEK cells to analyse the expressed OR molecules for their interactions to TMT. (c) Six different ORs that demonstrated high affinity to TMT were analysed by the luciferase assay for their interactions to eight different agonists at various concentrations. All values are in mean±s.e.m.; n=4. TMT, 2,4,5-trimethyl thiazoline; 2MT, 2-methyl-thiazoline; 4MT, 4-methylthiazoline; 2E4MT, 2-ethyl-4 methyl-thiazoline; AP, acetophenone; APA, allyl-phenyl-acetate; Car, carvone; 7-OH, heptanol.