Tricholine citrate

Sucrose, denatonium, quinine, papaverine, caffeine, strychnine, L-canavanine, N,N-diethyl-m-toluamide (DEET), sulforhodamine B, KCl and tricholine citrate were purchased from Sigma-Aldrich (Saint Louis, MO). Berberine sulfate trihydrate and Brilliant Blue FCF were obtained from Wako Pure Chemical Industries, Ltd (Osaka, Japan).

Berberine, caffeine, denatonium, lobeline, sucrose, sucrose octacetate, strychnine, sulforhodamine B, tricholine citrate, and umbelliferone were purchased from Sigma-Aldrich (Saint Louis, MO). Brilliant blue FCF was purchased from Wako Pure Chemical Industries, Ltd (Osaka, Japan).

Extracellular tip-recordings from labellar taste bristles were performed as previously described [66 (link)]. All tastants were dissolved in 30 mM tricholine citrate (Sigma, T0252), which functioned as the electrolyte [67 (link)]. Recordings were obtained from male flies aged 4–5 days at 25 C. Neuronal responses were amplified and digitized using IDAC-4 data acquisition software. Visualization and manual-quantification of action potential spikes were done with autospike software (Syntech). Number of action potential spikes generated in the first 500 ms following contact artifact was used to quantify neuronal responses.
For recordings with 7-tricosene, solutions were prepared by adding appropriate amounts of 7-tricosene to TCC solutions so as to attain a final TCC concentration of 30 mM right before the day’s experiments. Solutions were kept on ice and vortexed right before filling the recording electrodes. Recording electrodes were filled with 7-tricosene solutions by injecting the solutions into them. Electrodes for 7-tricosene application were used only once.