Fig. 4

The diwanka gene acts cell-nonautonomously to specifically control the migration of motor axons. embryos. In diwanka mutant embryos (B), zn-5 staining of retinal ganglion cells (asterisk) and the optic nerve appear indistinguishable from wild-type embryos at 72 hpf (A). Engrailed (4D9) staining of wild-type (C) and diwanka mutant (D) embryos at 26 hpf. In wild-type and mutant embryos, Engrailed-positive muscle pioneers are located in the anterior portion of the somites. Dashed lines indicate somitic boundaries. (E, F) Chimera analysis of diwanka mutant embryos with a large secondary motor neuron clone. (E) Confocal image of the zn5 stained chimeric diwanka embryo reveals aberrant motor trajectories (arrows and arrowheads). Same embryo and confocal section, now including the rhodamine signal to visualize wild-type derived cells in red. In a diwanka mutant host embryo, wild-type derived motor axons display aberrant, diwanka-like pathfinding defects (arrows, arrowheads and asterisk). (G, H) GFP-positive secondary motor neurons from diwanka mutant embryos expressing TG(GATA2:GFP) were transplanted into wild-type hosts. (G) GFP-positive diwanka motor axons extend along wild-type trajectories, demonstrating that diwanka acts cell-nonautonomously. (H) Same embryo and confocal section, now including the rhodamine signal to visualize all wild-type-derived cells in red. White asterisks indicate motor neuron soma, and white arrows point to their axonal trajectories.