Fig. 5.
TH neurons modulate flight through direct contact with flight motoneurons. (A) Confocal image of thoracic muscles of fly expressing myristoylated GFP in dopaminergic neurons (TH>Myr:GFP). No GFP signal can be observed. (B) Schematics of a dopaminergic synapse and receptors. (C and D) Average flight duration (C) and force flight (D) at 30°C of flies with downregulated expression of dopamine receptors (DAMBRNAi) in specific flight motor neurons. (E) Red light-evoked (red shade) activation of Dlm motoneuron expressing CsChrimson (Dlm-Mn>CsChrimson) induces spontaneous flight (n ≥ 15). See also Movie S8. (F) Flies with Dlm neurons inhibited by expression of Kir2.1 show reduced flight duration. (G) Representative confocal images showing the projections of Dlm motoneurons within the VNC (Left panel) and longitudinal flight muscles (Right panel). (H) Cartoon illustrating the principle underlying GFP Reconstitution Across Synaptic Partners (GRASP). GFP is reconstituted when two complementary segments of GFP associate on the extracellular surfaces of adjacent neurons. (I) Confocal image of GRASP reconstitution in the VNC of Drosophila TH;Dlm-Mn>GRASP (TH-LexA>LexAOP:RFP,LexAOP:spGFP11 & Dlm-Mn-Gal4>UAS:spGFP1-10). GRASP fluorescence reveals structural links between TH and Dlm neurons in the VNC. (J) Cartoon illustrating the experimental approach to determine a functional connection between TH and Dlm neurons. (K) Red light-evoked (red shade) activation of TH neuron expressing CsChrimson (TH>CsChrimson) induces spontaneous activity of Dlm motoneurons in Drosophila TH;Dlm-Mn>CsChrimson;GCAMP6 (TH-LexA,LexAOP:CsChrimson;Dlm-Mn-Gal4,UAS:GCAMP6m) compared to controls. See also Movie S9. Error bars represent SEM. Significant values in all figures based on Mann–Whitney U test or one-way ANOVA with the post hoc Tukey–Kramer test: *P < 0.01, ∗∗∗P < 0.001.