An approximately 4.5kb Kr regulatory fragment from upstream of the Kr transcription start site is fused upstream of the Kr core promoter (sequence extends to the beginning of the second exon) followed by 24 copies of the Tag:MS2 stem loop and lacZ. The proximal (CD2) and distal (CD1) blastoderm enhancers normally present in the Kr regulatory fragment have each been replaced with equivalent length of 'neutral' sequence.