Figure 5.

Postsynaptic localization of GluRIIA, GluRIIB, and DLG requires contact by the presynaptic neuron, but localization of DLG does not depend on the presence of glutamate receptors A: Confocal projections of late stage 17 embryonic NMJs visualized using antibodies to the neuronal membrane marker anti-HRP (green) and anti-GluRIIA subunit antibodies (magenta). This image shows NMJs on interior-most ventral longitudinal muscles in two neighbouring hemisegments in a prospero null mutant. The muscles in the upper hemisegment are normally innervated; the muscles in the lower hemisegment are not innervated. Major anatomical landmarks are labelled: In the upper hemisegment, intersegmental nerve branch b (ISNb) enters from the right (medial) and branches to form NMJs on muscles 7 & 6, 13, and 12. ISNb is absent in the uninnervated hemisegment. Note the lack of GluRIIA clusters in this hemisegment. B: Uninnervated muscles 6 & 7 in a prospero mutant embryo, stained using antibodies against GluRIIB, DLG, and the neuronal membrane marker HRP. Note the lack of GluRIIB clusters, and dispersal of DLG throughout the muscle membrane. C: Innervated muscles 6 & 7 in a GluR-less Df(2L)SP22 mutant embryo, stained using antibodies against the synaptic vesicle protein cysteine string protein (CSP, green)) and DLG (magenta). Note that DLG clusters properly at the synapse. Scale bars (A, B, C) = 15 μm.