Figure 1. I7 OSNs Respond ~10 Times More Sensitively to Heptanal than to Octanal.

(A) Schematic representation of experimental strategy. I7 OSNs (green) were identified by green fluorescence in an intact epithelial preparation. Their firing of action potentials was recorded extracellularly from dendritic knobs in cell-attached mode. Odorants were applied by pressure through a seven-barrel pipette.

(B) Strong green fluorescence in the dendritic knob and cilia of a GFP⁺ I7 OSN.

(C) Traces showing the responses evoked by heptanal at different concentrations as indicated by the numbers to the left (in μM). Horizontal bars indicate the timing of odorant application (300 ms). In this and the following figures, heptanal is abbreviated as 7al and octanal as 8al.

(D) Reponses of another I7 OSN to octanal at different concentrations.

(E) Dose-response plots and fitted sigmoid functions of I7 OSNs to heptanal (n = 10 cells) and octanal (n = 10 cells). The response strength was normalized to the mean saturated firing frequency to heptanal. Error bars indicate SEM in this and the following figures.

(F) Mean and individual EC₅₀ values of different I7 OSNs to heptanal and octanal. ***p < 0.001 (between-group t test).