Figure 4 Ephrin signaling has asymmetric requirements in amphid commissure ventral guidance. (A) Amphid outgrowth defects display left-hand bias in Eph signaling mutants; representative example from
efn-1(
e96). Bar, 10 mm. (B) Quantitation of axon guidance defects in left vs. right hand AWB, ASI, or AFD axons in
efn-1 or
vab-1(
e118) mutants.
unc-40 and
sax-3 do not show detectable left- right bias in penetrance. Green bars are right-side axons and red bars, left. (C) Transformation of ASEL into an ASER-like fate by
lsy-6 does not alter the left-hand bias in guidance defects in
vab-1 (
e2027) background. (D) Asymmetry in Pefn-2- mCherry (juEx2737) expression as determined by 4D lineage analysis at 335 min postfertilization; anterior is to the left and left is up. Blue nuclei are bilateral pairs that show symmetrical expression of
efn-2, green nuclei are members of bilateral pairs for which only the right-hand side expresses
efn-2, red nuclei are members of pairs that express only on the left-hand side. Gray nuclei are nonexpressing (grayscale depth code). See Table S2 for list of expressing nuclei. (E) Loss of
efn-2 function increases asymmetry of
efn-1 mutants, does not affect
vab-1(
e2027) or
vab-1(
dx31) null mutants, and decreases penetrance and asymmetry in
vab-1(kd).