Fig. 2. Localization of MSL complexes to roX1c3.4 transgenes. MSL1 localization in male nuclei, detected by immunostaining with anti-MSL1 antibodies (red). (A) Expressed antisense construct [Hsp83–roX1AS]87A, (B) [roX1c3.4]66C, from which transcription has not been detected, (C) [roX1c3.4]33DE, (D) [roX1c3.4]51A. The [roX1c3.4] transgenes show MSL1 binding at the insertion sites of the transgenes (B–D, arrows), as well as in neighboring regions (C and D, arrowheads). (E) Northern analysis shows fusion RNA expression of roX1 from flanking sequences in the [roX1c3.4]33DE and [roX1c3.4]51A lines, in which relatively frequent spreading was also observed. All transgenic lines carry a mutant allele (roX1^ex6) at their endogenous roX1 locus. The [roX1c3.4]66C, 52DE and 47C lines do not express detectable roX1 RNA. The wild-type strain (y w; WT) expresses endogenous roX1 RNA.