Dank2 and the neuronal, nrg¹⁸⁰ protein form are coexpressed in theDrosophila embryonic nervous system, and the absence of neuroglian protein decreases the level of Dank2 in embryonic neurons and nerve tracts. Shown are dissections of Drosophilaembryos, which were stained using either the anti-nrg¹⁸⁰ mAb BP-104 (A,D) or a mouse anti-Dank2 antiserum (B,C, E, F).D–F represent larger magnifications of the embryos inA–C. Whereas the dissections shown in Aand D versus B and E are from wild-type embryos, the embryo in C andF is a homozygous mutant for neuroglian (nrg¹ ). The arrowheads inD–F indicate the axons of the segmental and intersegmental nerves. To discriminate between heterozygous and homozygous neuroglian mutant embryos, dissections were first stained with the anti-neuroglian mAb 1B7, and unstained embryos were subsequently incubated with anti-Dank2 antibodies. Scale bar:A–C,120 μm; D–F, 40 μm.