Figure 6.

Strychnine inhibition of sucrose responses persists in labellar s6, i9, and l5 sensilla of Gr66a>DTI flies. Extracellular responses recorded from sensilla on the labellum (mean ± SEM) in s6 (left), l5 (middle), and i9 (right) sensilla in Gr66a>DTI (red squares) and the parental lines (triangle, UAS–DTI; circle, Gr66a–Gal4). A–C, Responses to 0.01, 0.1 and 1 m sucrose were dose dependent in all strains in s6 sensilla (A; Gr66a>DTI, n = 6; Gr66a-Gal4, n = 5; UAS–DTI, n = 5), l5 sensilla (B; n = 7, 6, and 5, respectively), and i9 sensilla (C; n = 11, 6, and 5, respectively). D–G, Responses to 0.001, 0.1, and 10 mm strychnine were reduced in s6 sensilla (D) of Gr66a>DTI flies (n = 7, 6, and 5, respectively) but not in l5 sensilla (E) that are not activated in response to bitter chemicals (n = 6, 5, and 6, respectively) and in i9 sensilla (G) that are not sensitive to strychnine (n = 10, 5, and 5, respectively). F, To check that the bitter-sensitive neuron was ablated in i9 sensilla, we tested the responses to 0.001, 0.1, and 10 mm caffeine (n = 11, 5, and 5, respectively). H–J, Responses to a mixture of 0.1 m sucrose and 0.001, 0.1, and 10 mm strychnine in s6 sensilla (H; n = 6, 6, and 5, respectively), l5 sensilla (I; n = 7, 6, and 5, respectively) and i9 sensilla (J; n = 11, 5, and 5, respectively). A dose-dependent effect of strychnine was found in all three sensilla in the three strains. These data were analyzed with a GLIMMX procedure. Abscissa, Log₁₀ of the molar concentration. **p < 0.01, ***p < 0.001. suc, Sucrose; stry, strychnine; caf, caffeine.