Figure 1.

Morphological defects in amphid chemosensory neurons of sax-1 and sax-2 mutants. Each neuron extends one straight anterior dendrite and one U-shaped axon that enters the nerve ring. Neuronal morphology was characterized with integrated transgenes that express GFP in AWC (top row), ASER (middle row), and ASJ (bottom row, closed arrowheads). All panels show a lateral view of one side of the animal. Anterior is to the left, dorsal at top. Bar, 10 μm. Panels show wild-type (A, D, and G), sax-1(ky211) (B and H), sax-1(ky491) (E), and sax-2(ky216) (C, F, and I) animals. The AWC and ASE neurons exhibited expanded and irregular cell shape defects in sax-1 and sax-2 mutants. The ASJ neurons produced ectopic, posteriorly misdirected neurites (H and I, arrows) in addition to the axon in the nerve ring (G, H, and I, open arrowheads). ASI neurons also have a normal axon in the nerve ring and a posterior ectopic neurite (Zallen et al., 1999).