Fig. 1. unc-119(ed3) mutants have branched motorneuron axons. (A) Confocal micrograph of a wild-type young adult (38 hours after hatching) expressing GFP in GABA neurons. Anterior is to the right; posterior to the left. GFP was expressed in 19 D-type motorneuron cell bodies located along the tightly fasciculated ventral nerve cord (open arrow) and their commissures (arrowhead). The dorsal nerve cord was contiguous along the length of the animal (arrow). (B) Confocal micrograph of an unc-119(ed3) young adult expressing GFP in GABA neurons. There were branches in many of the axons that reached the dorsal cord (arrowheads), and large gaps in the dorsal nerve cord (solid arrow). The ventral nerve cord was defasciculated (open arrow). (C) GABA motor neuron structure was abnormal in unc-119(ed3) mutants scored at 38 hours after hatching. All wild-type axons were normal (left, n=21 worms, 273 axons). Although some unc-119(ed3) axons were normal (left, 27% ±2.8, n=9 worms, 144 axons), many reached the dorsal midline but failed to extend normally along the dorsal nerve cord (middle left, 30% ±3.9), many axons were branched (middle right, 31% ±6.0), and some axons failed to reach the dorsal nerve cord (right, 12.3% ±3.0). These differences from wild-type are significant (asterisk *, P<0.0001, t-test; error bars represent standard error of the mean). (D) Confocal micrograph of unc-119(ed3) axons branching at the dorsal body wall muscle. Brightfield illumination revealed the border between muscle and intestine (dotted line). Axons branched at the muscle (arrow) and at the lateral nerve cord (arrowhead). The dorsal nerve cord is marked by an open arrow. Scale bars (A,B) 25 µm, (C) 10 µm.
