Figure 6.
unc-40 and sax-3 mutants exhibit vem-1(rz1)-like axon patterning defects. In wild-type animals, the rhIs4 reporter labels VNC-associated interneurons-axons (arrows), as well as the bilaterally symmetric PVC tail neurons (right arrowhead) that extend anteriorly projecting axons along the right VNC. B, C, In some vem-1(rz1);rhIs4 and unc-40(e271);rhIs4 animals, a subset of axons from the nerve ring fail to project ventrally into the VNC and instead extend posteriorly in an inappropriate lateral position (arrows). D, In some unc-40(e271);rhIs4 animals, the PVCL axon also fails to properly extend to, and join, the VNC and instead travels in an aberrant lateral position (arrows) to the nerve ring. Inset, The initial segment of the trajectory followed by the mispositioned PVCL axon (arrows) at higher magnification. E, In 52% of the sax-3(ky123);rhIs4 animals examined, a small subset of posteriorly projecting axons that arise from nerve ring-associated neurons extend in an aberrant lateral position toward the tail (arrows). F, unc-40(e271);vem-1(rz1);rhIs4 animals are in distinguishable from unc-40(e271);rhIs4 animals for the aberrant lateral axon phenotype. Arrows point to an axon that fails to turn ventrally to join the VNC and instead travels longitudinally in an inappropriate lateral position and terminates just before reaching the vulva. G, sax-3(ky123);vem-1(rz1);rhIs4 animals exhibit an aberrant lateral axon phenotype that is much more penetrant than that observed in either the vem-1 or sax-3 null mutants alone. Arrows point to an aberrant lateral axon that turns dorsally after reaching the vulva to project anteriorly toward the head. A-G, The midbody arrowhead marks the position of the vulva. H, Quantification of axonal defects observed in unc-40(e271);rhIs4, unc-40(e271);vem-1(rz1);rhIs4, unc-40(e1430);rhIs4, unc-40(e1430);vem-1(rz1);rhIs4, sax-3(ky123);rhIs4, and sax-3(ky123);vem-1(rz1);rhIs4 animals (*p < 0.001; **p < 0.01). n.s. indicates that the PVC lateral axon defect was not scored in unc-40(e1430); rhIs4 and unc-40(e1430);vem-1(rz1);rhIs4 animals. I, Quantification of axonal defects observed in unc-40(e271);juIs76, unc-40(e271);vem-1(rz1);juIs76, unc-40(e1430);juIs76, and unc-40(e1430);vem-1(rz1);juIs76 animals (p < 0.001).