Fig. 4. Distribution of histone H3K4me2 in germ cells of S. ocellaris male larvae at 1 day (1d), 3 days (3d), 5 days (5d) and 10 days (10d) from hatching. (A-D) Chromatin DAPI staining, (A'-D') indirect immunolabelling with anti-H3K4me2 antibody and (A"-D") superimposed images where antibody staining is in red. (A,B) Maternal chromosomes appear condensed (long arrows) whereas paternal chromosomes, less stained with DAPI, initiate decondensation (short arrows and arrowhead); H3K4me2 staining is restricted to the maternal chromosome set. Arrowhead in (B) denotes the paternal chromosome corresponding to the longest autosomes pair. (C) Maternal chromosomes remain condensed (long arrows) whereas paternal ones appear totally decondensed (short arrows); (C',C") H3K4me2 labelling is restricted to the chromatin corresponding to the maternal chromosome set. (D) All chromosomes appear equally condensed and exhibit similar levels and distribution of H3K4me2 labelling (D',D"). Bar, 10 µm.