Figure 3.

Disruption of Goα phenocopies synaptic overgrowth of octß1r. A, B, Confocal Z-stack projections of type II arbors at muscle 12 in larvae expressing mCD8-GFP in octopaminergic neurons before and after bath application of octopamine. A, Bath application of octopamine increases the number of synaptopods on type II arbors (white arrowheads). B, Bath application of octopamine in the presence of PTX results in significantly larger increase of synaptopods than octopamine alone (white arrowheads). C, Quantification of the net increase of synaptopods in A and B per 100 μm of type II arbor, showing that octopamine induces a larger increase in synaptopods in larval preparations with 2 h PTX incubation than preparations without PTX treatment [N (left to right) = 18, 13, 16 NMJs]. D–F, Confocal Z-stack projections of type II arbors at muscle 12 in larvae expressing mCD8-GFP in octopaminergic neurons of control (D), animals expressing PTX in type II (E), and animals expressing Goα-RNAi1 in type II (F), showing a marked increase in the number of natural synaptopods (white arrowheads). G, Quantification of natural synaptopods per 100 μm of type II arbor in animals expressing PTX, Goα-RNAi, or Giα-RNAi in type II, showing that that the disruption of Goα function but not Giα results in increased number of natural synaptopods [N (left to right) = 175, 12, 25, 19, 10, 11, 10 NMJs]. Animals used in RNAi experiments were reared at 29°C to increase knockdown efficiency. H, Quantification of type II boutons at muscle 12 in animals expressing PTX, Goα-RNAi, or Giα-RNAi in type II motorneurons alone or type I+II motorneurons, showing that that the disruption of Goα function but not Giα results in increased number of type II boutons. [N (left to right) = 22, 16, 12, 20, 24, 16, 16, 10, 16 NMJs]. I, Quantification of natural synaptopods per 100 μm of type II arbor in octß1r mutants, octß1r/+ heterozygotes, goα⁰⁰⁷/+ heterozygotes, and goα⁰⁰⁷/+; octß1r/+ transheterozygotes, showing that goα⁰⁰⁷/+; octß1r/+ transheterozygotes have increased number of natural synaptopods, indicating a genetic interaction [N (left to right) = 175, 21, 11, 10, 11 NMJs]. J, Quantification of type II boutons at muscle 12 in animals of the same genotypes in I, showing that octß1r/+; goα⁰⁰⁷/+ transheterozygotes have increased number of type II boutons, indicating a genetic interaction [N (left to right) = 22, 15, 16, 12, 16 NMJs]. Scale bar, 12 μm. Error bars indicate SEM. ***p < = 0.0001; **p < = 0.001; *p < 0.05.