UAS regulatory sequences drive expression of an inverted repeat of Ecol\lacZ coding sequences (nucleotides 3090-3835 relative to GenBank accession J01636). One copy of the repeat used to generate the construct had an EcoRI site at the nucleotide 3090 end and a SfiI site (top strand sequence GGCCATCTTGGCC) at the nucleotide 3835 end. The second copy of the repeat used had a XhoI site at the nucleotide 3090 end and a different SfiI site (top strand sequence GGCCTAGATGGCC) at the nucleotide 3835 end. The resulting SfiI site created in the construct has a central ATCTA sequence that is nonpalindromic. Consequently, the inverted repeat has imperfect dyad symmetry.