Fig. 2. Co-localisation of macroH2A1.2 and HP1ß in spermatocytes. (blue, DAPI staining; green, anti-macroH2A1.2 antibody; red, anti-HP1ß antibody; yellow/orange, co-localisation of anti-macroH2A1.2 and anti-HP1ß antibodies). (A-D) Histone macroH2A1.2 begins to concentrate over the XY-chromatin in early pachytene spermatocytes (B, arrow) before a DAPI-dense XY-body is detectable (A). HP1ß is concentrated in two foci within the XY-body (C, long and short arrows); these foci are presumably associated with the X centromere and synapsed PARs (Turner et al., 2001). The arrowheads in B mark the filamentous structures detected by macroH2A1.2 antibodies. (E-H) In mid/late pachytene spermatocytes (with DAPI dense XY bodies, arrowhead in E) histone macroH2A1.2 and HP1ß are now both concentrated throughout the XY-body, with one particularly dense focus, presumably associated with the X centromere (long arrow). Both proteins are also concentrated at the centromeric heterochromatin of autosomes. The XY-body-associated macroH2A1.2-positive/HP1ß-negative focus (short arrow) is undoubtedly the Y centromere (Turner et al., 2001). (I-L) In diplotene spermatocytes (with an internalising XY-body, arrowhead in I), macroH2A1.2 and HP1ß remain concentrated at autosomal centromeres. However, the XY-body-located staining pattern is now quite distinct, with the concentration of macroH2A1.2 restricted to the X and Y centromeres and the PAR focus (arrows in J), whereas HP1ß is uniformly concentrated throughout the XY-body. (Note: a DAPI dense sperm head is apparent in I.) Scale bars: 10 µm.