Transcription on acetylated chromatin. (a) The nascent Br-RNA(green) and H4 K16Ac (red) signals are closely associated. BrUTP incorporation inhuman lymphocyte was carried out for 15 min and after fixation immunolabeledtogether with histone H4 K16Ac (rabbit antibody). (b) The deconstruction ofcell nuclei. After sarkosyl treatment, chromatin was spread and immunolabelledwith H4 K16ac, to show tracks of hyperacetylated chromatin. (c) Thecolocalisation of Br-RNA after BrUTP and H4 K16ac. Br-RNA appears as little spotson tracks of acetylated chromatin, equivalent images were obtained when P-RNA polII (Ser2) antibody (H5) was used. (d) Tracks of acetylatedchromatin appeared in clusters. (e) The distribution of sizes of chromatinacetylated tracks. (f) The distribution of sizes of chromatin betweenconsecutive acetylated tracks. (g) Expression data from FCDP mix cells onmouse chromosome 10. Expressed genes tend to cluster along the chromosome. Forcluster analysis we used a 500 Kb window. When clustering was significant (p>0.95)a blue line is drawn. Bars: a = 2 μm, merge = 200 nm; b, c, d = 10μm.