Synaptic pMad is dispensable for the NMJ overgrowth.

<p>(A-D) Confocal images of NMJ4 boutons (A and D) (quantified in B-C) from larvae of indicated genotypes immunostained for pMad (red), HRP (blue), which labels the neuronal surface, and GluRIIA or Brp (green). (A) pMad localizes as discrete puncta at control and <i>nwk</i> or <i>hiw</i> mutant NMJs, but is absent in <i>GluRIIA; nwk</i> and <i>hiw; GluRIIA</i> double mutants. Loss of synaptic pMad caused by mutations in <i>GluRIIA</i> does not rescue the aberrant morphology of <i>nwk</i> mutant NMJs, and not prevent the NMJ overgrowth of <i>hiw</i> mutants. (D) Local pMad levels are reduced at <i>imp</i> mutant NMJs and elevated in <i>nwk</i> mutants. Loss of <i>nwk</i> restores the synaptic pMad at <i>imp</i> NMJs (<i>imp; nwk</i>), but morphology remains similar to <i>nwk</i> alone. Muscle overexpression of <i>GluRIIA</i> restores the synaptic pMad, but not the NMJ growth to <i>imp</i> mutants (<i>imp; M>IIA</i>). The number of NMJs examined is indicated in each bar. Genotypes: control (<i>w</i>^<i>1118</i>), <i>nwk</i> (<i>nwk</i>^<i>1/γ3</i>), <i>IIA; nwk</i> (<i>GluRIIA</i>^{<i>SP16/Df</i>}<i>; nwk</i>^<i>1/γ3</i>), <i>hiw</i> (<i>hiw</i>^<i>ND8</i>), <i>hiw; IIA</i> (<i>hiw</i>^<i>ND8</i><i>; GluRIIA</i>^{<i>SP16/Df</i>}), <i>imp</i> (<i>imp</i>^<i>24/70</i>), <i>imp; nwk</i> (<i>imp</i>^<i>24/70</i>; <i>nwk</i>^<i>1/γ3</i>), <i>imp; M>IIA</i> (<i>UAS-GluRIIA</i>/<i>+</i>; <i>imp</i>^<i>24/70</i>; <i>24B-Gal4/+)</i>. Error bars indicate SEM. ***; p<0.001, **; p<0.01, *; p<0.05. Scale bars: 10 μm and 1 μm (details).