Figure 1. Flies avoid Ca²⁺ via ppk23 GRNs.

(A—D) Two-way choice taste assays. 50—70 flies/assay

(A) Preferences of control flies (w¹¹¹⁸) to 2 mM sucrose alone versus 2mM sucrose and the indicated concentrations of CaCl₂. n=4.

(B) Preferences of control flies to 1 mM sucrose alone versus 5 mM sucrose and the indicated concentrations of CaCl₂. n=4.

(C) Two-way choice assays after ablating different GRNs by UAS-hid under control of the indicated GAL4s. n=4.

(D) Effects of ablation of ppk23 GRNs (UAS-hid/ppk23-GAL4) on Ca²⁺avoidance. n=4.

(E—G) Assaying Ca²⁺-induced action potentials using tip recordings.

(E) CaCl₂ (50 mM)-induced action potential frequencies in control and UAS-hid/ppk23- GAL4 sensilla. n=10–24.

(F) Responses of L4 and S5 sensilla to different CaCl₂ concentrations . n=17–22.

(G) Tip recordings from S5 and L4 sensilla using 0—50 mM CaCl₂.

(H—J) Effects of different salts on sucrose-induced action potentials in L4 and L6 sensilla. The pipets contained 50 mM sucrose and 0—50 mM salts: (H) CaCl₂, (I) MgCl₂, (J) NaCl. n≥10. Error bars indicate SEMs. ANOVA tests with Scheffe’s post hoc analyses between control and ppk23-GRNs ablated sensilla. *P < 0.05, **P < 0.01.