Fig 4. Male-specific lethal 2 (msl-2) knockdown blocks expression of Msl-2 and acetylated histone H4 lys16 (H4K16) in elav^c155>Sxl RNAi females.

(A) Expression of Msl-2 and Elav (a neuronal marker) with DNA stained by DAPI in central nervous systems (CNSs) from early L3 larvae of the indicated sex and genotype. Left panels show single confocal sections close to the neuropil, where functional neurons, not immature postembryonic neurons, predominate. Centre and right panels show higher magnification views of boxed regions in the left panels. Msl-2 in control males localises to nuclear foci, consistent with its X chromosome localisation, and it is weak/absent in control females. In elav^c155>Dcr2 + Sxl RNAi 1 + msl-2 RNAi females, Msl-2 is expressed at moderate levels, and this ectopic Msl-2 is suppressed in elav^c155>Dcr2 + Sxl RNAi 1 females. Bottom graph shows quantification of Msl-2 expression (mean fluorescence intensity) measured in a region of interest similar to the boxed regions. Note that mean fluorescence intensity levels in control female levels likely reflect background signal. (B) Expression of histone H4 acetylated at lysine 16 (Ac-H4K16) with DNA stained by DAPI in CNSs from early L3 larvae of the indicated sex and genotype. Left and right panels show high magnification views from similar regions of the CNS as shown in A. Ac-H4K16 in control males strongly localises to nuclear foci (the X chromosome) and, in both sexes, lower signal intensity is observed throughout the nucleus (autosomes). Ac-H4K16 nuclear foci are observed in elav^c155>Dcr2 + msl-2::HA and elav^c155>Dcr2 + Sxl RNAi 1 females but not in elav^c155>Dcr2 + Sxl RNAi 1 + msl-2 RNAi females. The underlying data for this figure can be found in S1 Data.