Or22a cDNA sequence been inserted into the attP site in TI{TI}Dsec\Or22aRFP, allowing expression of a mutated form of Or22a (carries a M93I amino acid replacement) under the control of Dsec\Or22a regulatory sequences. 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}Dsec\Or22aRFP chromosome) 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.