Or22a cDNA sequence has been inserted into the attP site in the TI{TI}Df-Or22ab-RFP sequence cassette carried on the Df(2L)Or22ab-RFP chromosome, reconstituting a Or22a locus encoding the wild-type protein. A Avic\GFPEGFP.3xP3.Tag:NLS(tra) marker has also been inserted. The Disc\RFPDsRed(T1).3xP3.cHa marker (present in the progenitor TI{TI}Df-Or22ab-RFP) is still present downstream of the inserted sequence. The markers can be excised (either independently or together) using P1cre due to the presence of flanking loxP sequences. The chromosome still carries a deletion of most of Or22b.