Sd-L neurons are labelled by both iav and vGluT, and they are necessary for fine texture sensing.

(a) Iav-Gal4 drove expression of tdTomato (red, anti-RFP) in the labellum (iav-gal4 > UAS- tdTomato). Scale bar, 50 μm. (b) Iav-Gal4 drove expression of tdTomato (red, anti-RFP) under the restriction of vGluT-Gal80 in the labellum (iav-gal4, vGluT-gal80 > UAS- tdTomato). Scale bar, 50 μm. (c) Co-localization between vGluT-QF (vGluT-QF > QUAS-mCD8-GFP, green, anti-GFP) and iav-Gal4 (iav-Gal4 > UAS-CD4-tdTomato, red, anti-RFP) in the labellum. White arrow pointed to sd-L neurons. Scale bar, 50 μm. (d) The preference of food hardness when sd-L/nan/tmc neurons were inhibited by TNT in the two-way choice feeding assay. 10 mM sucrose was added to different concentrations of agarose. Statistical test: one-way ANOVA with Dunnett’s correction for multiple comparisons against the sd-L-SS/nan-gal4/tmc-gal4 > UAS-TNT group; mean ± SEM; n = 11~19 for each group. (e) The rescue for the defects of iav mutant by expressing iav wild-type cDNA in the sd-L neurons. Sd-L neurons were labeled by R41E11-gal4. Statistical test: one-way ANOVA with Dunnett’s correction for multiple comparisons against the R41E11-gal4 > UAS-TNT group; mean ± SEM; n = 27, 29, 19, 36 for each group. (f) GRASP signal (green, anti-GFP) between iav-LexA and TMC-gal4 neurons (iav-LexA > lexAop-CD4-spGFP11 and TMC-gal4 > UAS-CD4-spGFP1-10) in the SEZ. Scale bar, 50 μm. (g) Co-localization signal (green, anti-GFP) between iav-LexA and TMC-gal4 neurons (iav-LexA > 8×LexAop2-FLPL and TMC-gal4> 20xU>dsFRT>chrimson-mVenus) in the SEZ. Scale bar, 50 μm. Magenta: nc82. (TIF)