Fig. 3. Localisation of Me(3)K20H4 to nuclei either undergoing facultative heterochromatization or developmental de-heterochromatinisation. (A) DAPI-stained nuclei from a mid-cleavage stage embryo (128-256-nuclei embryo) that has undergone facultative heterchromatinisation. A clear, strongly-staining, chromocenter can be seen in each nucleus. The nuclei shown in A were labeled with C1A9 antibody (A') and with the anti-Me(3)K20H4 antiserum (A"); the merged image in A'" shows co-incidence of DAPI-positive chromocenters with C1A9 and Me(3)K20H4 staining. The nuclei in B are from another region of the same embryo that has yet to complete heterochromatinisation and several of them have no overt DAPI positive chromocenters. The DAPI-stained nuclei in B were stained with C1A9 antibody (B') and with the anti-Me(3)K20H4 antiserum (B"). Whereas the Me(3)K20H4 staining is more spread out in these nuclei compared with those that have completed heterochromatinisation (see B" and A") the merged image (B'") shows that the Me(3)H20H4 pattern largely colocalised with C1A9 staining. (C) DAPI-stained nuclei taken from cells of adult tissues that undergo developmental reversal of heterochromtinisation. C1A9 staining is dispersed and has a grainy appearance over the nucleus (C'). There is no staining of Me(3)K20H4 in the nucleus; rather, Me(3)K20H4 is found in the cytoplasm (C"). (C'") Merged image. Bars, 10 µm.