20 copies of the UAS site are fused upstream of the shi1 coding region (this encodes a temperature-sensitive dominant negative form of shi). A small intron derived from the Mhc gene has been inserted between the promoter and coding sequences. The 3' UTR (666bp) from the Autographa californica nucleopolyhedrovirus (AcNPV) p10 gene is present downstream of the coding sequence.