P{lacW} insertion in the open reading frame of the 1A cDNA.
Early lethal.
Embryos exhibit severe fasciculation defects, loss of neurons and concommitant increase in the size of the remaining cells. Mutants display gross defects in the axonal trajectories in the PNS. The intersegmental nerve grows from the dorsal cluster along aberrant pathways and often fails to connect to the lateral PNS cluster. Axons also cross segment boundaries in the dorsal, lateral and ventro-lateral region.
Excision of the P{lacW} is accompanied by a reversion to wild-type.
Δ2-3 induced reversion demonstrates the insertion is responsible for the lethal phenotype.