A 2kb genomic fragment, extending from -2061 to -61bp relative to the Fmo-2 translation start site is fused upstream of tdTomato tagged with a nuclear localization signal. The dsx protein-binding site (located between -842 and -830) and immediate flanking sequence in the Fmo-2 fragment has been changed to the orthologous D. erecta sequence (ACTGCAACATTGTTGCCA to gc-GCtACATTGTTGCgc).