Fig. 1. A cDNA fragment of roX1 recruits the MSL complex. (A) Diagram of the 3.4 kb roX1c20 cDNA driven by the Hsp83 promoter and a deletion derivative lacking a 30 bp segment that shares 25/30 identity with roX2. An intron near the 5′ end is indicated in each construct. The sequence comparison of roX1 and roX2 in the 30 bp region deleted in roX1Δ30 is shown below. (B) Polytene chromosomes from a [Hsp83–roX1]61B male. (C) Polytene chromosomes from a [Hsp83–roX1Δ30]21D male. Chromosome squashes were immuno stained with rabbit anti-MSL1 (red) and counterstained with 4′,6- diamine-2-phenylindole (DAPI) (blue). Both nuclei show a strong site of MSL localization at the insertion site of the respective transgenes (arrowheads). A heavily stained X chromosome is also seen in (B).