Sequence containing 20xUAS regulatory sequence upstream of the minimal Hsp70 promoter and IVS (intron) sequence has been knocked-in to the endogenous fru locus, just upstream of the P1 promoter (73bp of genomic sequence has been deleted at the insertion site). A loxP cassette containing a Disc\RFP3xP3.cUa marker has also been introduced during the mutagenesis event; this is located upstream of the UAS sequences.