UASt regulatory sequences are fused upstream of a coding sequence comprised of EGFP tagged at the C-terminal end with Tag:PEST(mOdc), followed by genomic FNA encoding the entire long dco 3'UTR, plus 500bp of genomic DNA from the dco locus downstream from the distal 3' cleavage site. A single nucleotide change has been introduced into the 3'UTR, converting a variant PAS (AATATA) into the canonical PAS (AATAAA) sequence.