Table 2. Motor neuron fasciculation and guidance defects in spon-1 mutants.
| (A) spon-1 single mutant defects | ||||
|---|---|---|---|---|
| Genotype, temp | n | Ventral cord defasciculationa | Commissure handedness defect | Dorsoventral guidance defect |
| N2 20° | 43 | 0% | 2.7% (0.2%) | 0% |
| ju430ts 15° | 42 | 40.5% (6.5%) ** | 30.9% (2.9%) ** | 9.5% (0.5%) ns |
| ju430ts 20° | 41 | 31.7% (4.9%) ** | 56.1% (8.7%) ** | 29.3% (2.4%) ** |
| ju430ts 22.5° | 40 | 17.5% (2.5%) * | 87.5% (15%) ** | 40% (4.1%) ** |
| ju430ts 15°-25° | 37 | 16.2% (4.1%) ** | 43.2% (4.7%) ** | 2.7% (0.2%) ns |
| upshift | ||||
| (B) Interaction between spon-1 and unc-71 | ||||
|
| ||||
| Genotype | n | Missing 1 or more commissures | Commissure handedness defect | Dorsoventral guidance defect |
|
| ||||
| N2 | 61 | 0% | 0% (0.2%) | 0% |
| unc-71(ju156) | 45 | 73% | 24% (5%) | 0% (0%) |
| ju430ts | 45 | 0% | 11% (3%) | 0% (0%) |
| ju430ts; ju156 | 48 | 100% *** | 44% (10%) | 44% (9%) ** |
D morphology was scored using the Punc-25-GFP (juIs76) marker in young adults (A), or in L1 larvae (B); only commissures of DD2-6 were scored in L1s. All defects are scored per animal (n) and per neuron/commissure (or per ventral cord segment for defasciculation). Data in part B are all at 20°C. Tests of significance use the Fisher exact test;
P < 0.05,
P < 0.01,
P < 0.001.
‘Ventral cord defasciculation’: The ventral nerve cord was divided into 10 sections between D neuron cell bodies. An animal is scored as defasciculated if 2 or more segments are defasciculated.
‘Commissure handedness defect’ is outgrowth of a commissure on the left side. The two anterior commissures (DD1/VD2) of the left side and most anterior commissure on the right side (VD3) were not scored.
‘Dorsoventral guidance defect’ is % animals with >1 commissure that fails to reach dorsal cord. About 8% of D neurons did not extend commissures from the ventral cord. We observed similar defects in A and B type motor neurons (not shown).