Figure 2

GluRIIB, but not GluRIIA, is lost from synapses in DLG mutants 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). Each panel shows NMJs on interior-most ventral longitudinal muscles in one hemisegment. Major anatomical landmarks are labelled: Intersegmental nerve branch b (ISNb) enters from the left (medial) and branches to form NMJs on muscles 7 & 6, 13, and 12. The top row of panels shows images from control embryos; the lower row of panels shows images from dlg mutant embryos. B: As in A, except anti-GluRIIB subunit antibodies (magenta) were used. Scale bar = 5 μm. C: Cumulative frequency plot of glutamate receptor cluster sizes, measured from images such as those shown in A &; B. GluRIIA cluster sizes (black squares) do not differ between control (filled squares) and dlg mutant (open squares) embryos. GluRIIB cluster sizes (magenta circles), however, are significantly smaller in dlg mutant embryos (open circles), compared to controls (filled circles).