Figure 1. Gr43a^GAL4 is expressed in chemosensory organs, the brain and the proventriculus.

(A-C) Expression of Gr43a in chemosensory organs. Gr43a^GAL4 drives strong UAS-mCD8GFP expression in neurons located in the fifth tarsal segment of the foreleg (A₁, live GFP), the LSO and the VCSO (B₁; live GFP), but only weak expression in the LPs (C1; immunostaining). Co-expression analysis in sweet neurons was performed in flies containing Gr43a^GAL4 and Gr64f^LexA, driving expression of UAS-mCD8RFP (detected with anti-CD8 antibody) and lexAop-rCD2GFP (detected with anti-GFP antibody), respectively. Co-expression analysis in bitter neurons was performed in flies containing Gr43a^GAL4 driving expression of UAS-mCD8RFP (detected with anti-CD8 antibody) and Gr66a-gfp (detected with anti-GFP antibody). LP, labial palp; LSO, labral sensory organ; VCSO, ventral cibarial sense organ. Arrowheads indicate Gr43a^GAL4 neurons.

(D)Gr43a^GAL4 is expressed in 2-4 neurons/hemisphere in the posterior superior lateral protocerebrum.

(E)Gr43a^GAL4 is expressed in approximately four neurons in the proventricular ganglion. Gr43a^GAL4 neurons innervate the lumen of the foregut, but not the crop duct (E₂, left inset; E₁). Some neurons send projections to the mid gut (E₂, right inset; E₁, arrow; E₃), others to the SOG (E₁, arrowhead). Pv, proventriculus; Cr, crop; Mg, mid gut.