Figure 4.
A minute impurity of ethyl acetate is sufficient to elicit a positive response to its mixture with benzaldehyde. We recorded antennal calcium responses in Or42b > GCaMP6m flies. Responses to benzaldehyde-h 10−2 were inhibitory. Gradually adding ethyl acetate in concentrations from 10−10 to 10−2 led to increasingly excitatory responses, in a dose-dependent manner (color-scale, see inset; for example, 0 in the legend means benzaldehyde-h at a dilution of 10−2; 10−7 in the legend means that ethyl acetate at a dilution of 10−7 was added to benzaldehyde-h at dilution 10−2, i.e., the relative concentration was 10−5). Gray: response to ethyl butyrate 10−2, for calibration. Odors were premixed in mineral oil to mimic the contamination situation, and delivered with a PAL multisampler. All traces: N = 3, average ± SEM. Gray bars indicate stimulation times.