Class A cDNA clone B3 of Zavortink and Sakonju, (Genes Dev 3:1969--1981 ) fused to an Hsp70 promoter.
Embryos that express Abd-Bhsm during 3-5 hours of development develop posterior spiracles (that are normally restricted to segment A8) in anterior segments. Embryos that express Abd-Bhsm during 5-7 hours of development do not develop ectopic posterior spiracles, but sensory organ development is abnormal; basiconic sensilla (which are normally restricted to segments A8 and A9) are found in segment A1-A7.
Ectopic expression of Abd-B m or r proteins induces A8 structures in thoracic and abdominal segments, indicating that r and m proteins can carry out similar functions.