Figure 4

arx mutants display fewer PQR growth cone filopodia. Shown are fluorescent micrographs of living animals with gcy-32::gfp expression in the PQR neuron in the tail of the animal posterior to the anus. Below each micrograph is a tracing showing the shape of the PQR neuron. (A-D) Time courses of wild-type posterior PQR neurite development (arrows). PQR neurons from different animals at particular timepoints are shown. A tracing of the cell and neurite is shown below each micrograph of animals at given timepoints after hatching (see Materials and methods). (E-H) PQR posterior neurite development in a representative example of an arx-2(ok1269M+) mutant. (I) The PQR posterior neurite from an unc-34(e951) mutant. (J-K) PQR neurons from unc-115(ky275); arx-2(ok1269M+) or unc-115(ky275); arx-7(ok1118M+) mutants at 9 h after hatching at a time when wild-type posterior protrusions had fully extended. The PQR in (J) showed a rudimentary posterior protrusion (arrow), and the PQR neuron in (K) showed no obvious posterior protrusion (arrow). The dashed arrows in (J) and (K) point to normal anterior axonal protrusions from these PQR neurons. Arrowheads indicate the PQR cell bodies. In all micrographs, anterior is to the left and dorsal is up, and the scale bars represent 2 μm (scale bar in (A) is for (A-I); that in (J) is for (J-K)).