The compartmentalization of histone marks were first assessed for their association with DAPI counterstaining dense DNA staining regions (DAPI-bright)- presumably heterochromatin- and the light DNA staining (DAPI-dim) regions- presumably euchromatin (13)- in undifferentiated NSC neurospheres. Nuclear 2me-H3K4 generally correlated DAPI-dim areas indicative of DNA-sparse and euchromatin orientation (Figure 3A, B arrowhead). The 3me-H3K27 associated closely with the DAPI-bright DNA, as indicated by the overlapping DAPI and 3me-H3K27-im granulation (Figure 3C, D arrow). Ac-H4 also appeared to associate with heterochromatin (Figure 3E, F arrow) in the undifferentiated neurospheres. The exception was when 2me-H3K4 associated with heterochromatin during metaphase (Figure 3A, B crossed arrow).
