Figure 4. unc-3 is expressed postembryonically in the VA and VB but not the VC or VD motor neurons.

Each set of four panels displays images of neurons showing (i) gfp from a motor neuron type-specific promoter, (ii) UNC-3 protein detected with UNC-3 antiserum (αUNC-3), (iii) DAPI, (iv) a merged image. Each set of four panels assesses expression of unc-3 in the indicated class(es) of motor neurons. Residual fluorescence from GFP after fixation was used to detect specific classes of motor neurons. (A) unc-3 is expressed in the class A motor neurons. Images are from animals carrying the P_unc-4gfp reporter, which is expressed in DA, VA and VC motor neurons (17, 39). unc-3 is not expressed in the VC neurons (see panel C). (B) unc-3 is expressed in the class B motor neurons. Images are from animals carrying the P_del-1gfp reporter, which is expressed in the VB motor neurons. In L3 animals the P_del-1gfp reporter is visible in some VA neurons at the anterior end of the ventral nerve cord (19). The more anterior nucleus of each pair of fluorescent nuclei in the anterior half of this image is a VA motor neuron and is marked by a small arrowhead above the nucleus. (C) unc-3 is not expressed in the VC motor neurons. Images are from animals carrying the P_lin-11gfp reporter, which is expressed in the VC motor neurons (13). (D) unc-3 is not expressed in the VD motor neurons. Images are from animals carrying the P_unc-47gfp reporter, which is expressed in the DD and VD motor neurons (40). Anterior, leftwards; ventral, downwards. Arrowheads indicate specific motor neurons identified by gfp expression. L3 animals were examined except for P_lin-11gfp, for which young adults were examined.