2.2kb fragment (2.2dis), located 2.5kb upstream from the start of transcription, with 1.5kb adjacent upstream sequence and the ci promoter sequence (1.2prx), including the first 5 codons of ci, are fused to codon 8 of lacZ.
EcollacZ expression is seen in the ventral midline and in the anterior portion of segmentally repeated stripes in the embryo, and in the anterior compartment of the wing disc.