Chromatin structure and composition in CDA-1 patients. (A) Electron microscopy of normal and CDA-1 cultured intermediate erythroblasts, and imaging of intranuclear chromatin bridging stained with May-Grünwald-Giemsa and by electron microscopy. (B) Silver staining of SDS-PAGE of histone extracts from cultured CDA-1 (patients A and B) and normal erythroblasts. (C) Western blots of total histones and histone marks. Quantification of histone marks relative to total histones (set to 1), adjusted to a normalized background.