KpnI-SmaI fragment of genomic DNA containing hb and both the P1 and P2 transcription start sites.
In hbKM, hb12 animals, a duplication of interneuron 2 is seen at the expense of the first born 1/1G neurons. In these mutants the aCC and RP2 motorneurons fail to project their proper dorsal muscle target, suggesting a transformation of GMC-1 to a later born GMC fate. Mutants show a general reduction in the number of motorneuron projections, particularly to the dorsal muscles. Mutants lack the first born MM-CB glia at the midline.