UNC-17 expression in motor neurons is decreased inunc-4 mutants. A, Left lateral view shows punctate pattern of UNC-17 antibody staining in the SAB-containing nerve cords in the head region of a wild-type animal.Arrows point to dorsal and ventral left sublateral processes. B, Punctate UNC-17 staining is reduced or eliminated in many of the head sublateral processes inunc-4(e120)-mutant animals. Note the absence of UNC-17 staining in the left ventral process containing SABVL.C, Ventral view of UNC-17 expression in wild-type VC axons that innervate the vulval muscles (arrowhead) is shown. D, UNC-17 staining of VC vulval projections is eliminated or reduced in unc-4(e120) mutants, but UNC-17 staining of other cholinergic processes in the VNC and ventral sublateral (SL) nerve cords is not noticeably affected. E–I, Left lateral views are shown. The unc-104 kinesin mutation was used to localize UNC-17 to the soma of ventral cord motor neurons (Hall and Hedgecock, 1991; Nonet et al., 1993). The nuclei of DA and VA motor neurons also express UNC-4:: GFP (see G) (Pflugrad et al., 1997). E, G, H, In animals that are wild-type for unc-4, strong UNC-17 antibody staining is visible in the cytoplasm of cholinergic motor neurons. F, I, In unc-4(e120) mutants, cytoplasmic UNC-17 staining is substantially reduced in theunc-4::gfp-expressing DA and VA motor neurons.H and I are enlargements of single VA neurons from E and F(arrows), respectively. Scale bars, 10 μm. Anterior is to the left.