Figure 1.

Bsg is expressed in the axons of the CNS, in the glia ensheathing the peripheral nerve, and at the NMJ. A-A′′, Brain lobes and VNC of WT third instar Drosophila larvae expressing endogenously tagged Bsg::GFP (green) with all glial cells labeled using repo-GAL4 driving expression of membrane marker mCD8::RFP (magenta). Bsg is expressed in the neuropil (asterisk) and the nerve roots of the VNC as well as the glial cells ensheathing the nervous system (arrowheads). Scale bar, 50 μm. B-B′′, Pan-glial knockdown of Bsg using RNAi with repo-GAL4 results in loss of Bsg expression in the peripheral nerves and the glia ensheathing the brain lobes and VNC (arrowheads), but not in the VNC neuropil (asterisk). Scale bar, 50 μm. C, D, Peripheral nerve showing expression of Bsg in the glial cells of the peripheral nerves. Scale bar, 15 μm. C′, D′, Cross section of the nerve at the point indicated (arrowhead) in the corresponding panel. E, F, Bsg::GFP expression is lost in the peripheral nerve following pan-glial knockdown of Bsg. Scale bar, 15 μm. E′, F′, Cross section of the nerve at the point indicated (arrowhead) in the corresponding panel. G-G′′, Expression of fusion proteins Bsg::GFP and Bsg::cherry in the VNC (asterisk). Bsg::cherry was created from Bsg::GFP using Recombinase-Mediated Cassette Exchange. Both lines are homozygous viable. Scale bar, 50 μm. H-J, Expression of Bsg::GFP and Bsg::cherry in the glia (arrowhead) ensheathing the peripheral nerves. Scale bar, 15 μm. H′, I′, J′, Cross section of the nerve at the point indicated (arrowhead) in the corresponding panel. K-K′′, Expression of Bsg::GFP and Bsg::cherry at the NMJ. Bsg is highly expressed in the synaptic boutons (arrowhead). Scale bar, 15 μm.