Figure 10. Motoneurons and muscles controlling the major steps of the PER motor program.
The extension of the proboscis in response to an attractive stimulus (200 mM sucrose, A–E) follows a stereotypic pattern that can be subdivided into a sequence of events. Snapshots of the motion pattern of a control fly (w1118) executing a continuous proboscis extension (left panels) and in the schematic drawings illustrating the direction of the movements (blue arrows) are shown. Muscles and MNs controlling the individual steps are indicated in the schematics (blue numbers) and in brains (right panels, inverted fluorescence images from Figures 5–8). MNs display a striking overlap in dendritic organization. Scale bar, 20 µm.
Figure 10—figure supplement 1. Spatial organization of MN dendrites in the SEZ.
(A–D) The expression pattern (mCD8-GFP, green) of three identified MN-Gal4-lines GMR26A01, chaGal80 MN2 (A), GMR81B12 MN6 (B), and GMR58H01 MN1,4,7,8 (C) is shown in comparison to the axonal projections of Gr5a-expressing sweet sensory neurons (D) in the adult central brain (Brp, magenta). For each genotype a front view (left panel), angled top view (middle panel), and a side view is shown. Scale bar, 50 µm.
Figure 10—figure supplement 2. Gr5a sensory neurons do not form synaptic connections with proboscis MNs.
Analysis of endogenous GRASP signal (green, top panels; white, bottom panels) between GMR26A01-Gal4 (A), GMR26A01-Gal4, chaGal80 (B), GMR58H01-Gal4 (C), VT020958-Gal4 (D), GMR81B12 (E), Gad1-Gal4 (F) and Gr5a-LexA. The neuropil is visualized using the presynaptic active zone marker Brp (blue, top row). Weak GRASP-signals are present in the combination GMR26A01-Gal4 to Gr5a-LexA (A). These signals are likely due to interneurons marked in the Gal4-line as no signal can be detected when expression is restricted to MN2 by using cha-Gal80 (B). Similarly, we did not detect significant GRASP signals in all other MN-Gr5 combinations but strong signals were present in the positive control gad1-Gal4 to Gr5a-LexA. Scale bar, 20 µm.