TABLE 2.
Shh Overexpression Induces Ectopic Motor Neurons in mind bomb Mutants
| Injected RNA | No. of embryosa | Wild-typeb | mind bombb | |
|---|---|---|---|---|
| Embryos with ectopic GFP- expressing cells in hindbrainc | None | 197 (3) | 0% (146) | 0% (51) |
| shh | 231 (3) | 94% (159) | 100% (72) | |
| Number of islet antibody-labeled cells in hindbraind | None | 5 (1) | 188 ± 16.6 | 104.7 ± 9 |
| shh | 5 (1) | 277.4 ± 11.4 | 148.8 ± 23 | |
| Ratio (shh / control) | 1.48 | 1.42 |
Numbers in parentheses represent number of experiments.
Numbers in parentheses represent number of embryos. Embryos were scored as mutant if the branchiomotor neurons exhibited fusion across the midline (Fig. 3B and D). The mutant embryo in Fig. 3D exhibited an unusually large increase in motor neuron number.
Embryos (36 hours postfertilization) were considered to have ectopic expression if the number of GFP-expressing branchiomotor neurons were increased relative to uninjected controls. The ectopic neurons were especially evident in rhombomeres 2 and 4 (Compare Fig. 3A and C), where ectopic neurons were located dorsally along the lateral margin of the neural tube, and in the caudal hindbrain.
The number corresponds to the total number of labeled cells (nV, nVII) in rhombomeres 2–7.