Fig. 2. Relatively few neurons co-express Gyc-89Da and Gyc-89Db. Flies were crossed to generate animals containing p89Da-GFP, p89Db-GAL4 and UAS-dsRed. Each panel shows a confocal z-stack, collapsed into a single plane with the red color representing cells expressing Gyc-89Da and the green color representing cells expressing Gyc-89Db. (A–D) Third instar larvae. (E) Adult. (A) Dorsal view (anterior is up) of the terminal organ (TO), terminal ganglion (TG), dorsal organ (DO) and dorsal ganglion (DG). Both ganglia contain cells that express either Gyc-89Da or Gyc-89Db but no cell shows co-expression of the two subunit genes. Also shown are two neurons that are part of the monoscolopidial organ (mc) that only express Gyc-89Db. (B) Lateral body wall showing the third thoracic (T3) and first two abdominal segments (A1 and A2). In T3 two neurons express both Gyc-89Da and Gyc-89Db (asterisks): a single `les' neuron (upper) and a single `ves' neuron (lower). In A1 and A2 a single `td' neuron expresses only Gyc-89Db (filled arrowheads). The fine red lines are trachea closely associated with fine branches from the two td neurons (open arrowheads). (C) Terminal segment showing the caudal sensory cones (SO1–SO7). Each cone contains a single neuron that co-expresses Gyc-89Da and Gyc-89Db. The inset shows a single neuron extending a neurite to a cuticular peg sensillum (p). (D) Larval CNS showing extensive expression of each subunit but no overlap in brain lobes (bl) and ventral nerve cord (vnc). Expression is also seen in the ring gland (rg). (E) Adult brain also shows extensive, non-overlapping expression of Gyc-89da and Gyc-89Db. A, anterior; P, posterior; e, eyes. Fluorescence seen in tracheae is due to autofluorescence. Scale bars represent 40 µm (A), 50 µm (C), 100 µm (B,D,E) and 25 µm (C inset).