Drosophila Importin-α2 Is Involved in Synapse, Axon and Muscle Development
Figure 3
Loss of Neuronal Importin-α2 Increases Active Zone Density.
(A–C) Representative confocal images of wild-type (y,w; FRT42D; +; +) larval NMJs from muscle 4 stained with antibodies against Bruchpilot (magenta), GluRIIC (green) and HRP (blue). Insets show high magnification images of individual boutons. Each Brp punctum is apposed by a corresponding GluRIIC punctum. (D–F) Representative confocal images stained as above in importin-α2 mutants (y,w; imp-α2D14; +; +). No defects in apposition are observed, but the density of both Brp and GluRIIC puncta is increased. Scale bar = 10 µm for full NMJ, 4 µm for high magnification images. (G–H) Quantification of Brp and GluRIIC puncta in wild-type larvae, importin-α2 mutants, and importin-α2 mutants with restored neuronal expression of Importin-α2 (y,w; imp-α2D14; elav-GAL4/UASt-Importin-α2; +). In importin-α2 mutants, the density of Brp and GluRIIC puncta per µm2 is increased by 40% and restored to wild-type levels by neuronal restoration of Importin-α2 expression. *** p<0.0001. (I–J) The synaptic area (as determined by anti-HRP staining of terminals) and the ratio of Brp to GluRIIC puncta are unchanged in the mutants. Error bars represent S.E.M. For all cases, n≥2 NMJs from 6 larvae.