Distribution of chromatin proteins over the regions corresponding to individual interbands in D. melanogaster polytene chromosomes. X axis shows 10 kb of a physical map for the specific region centered at the insertion site of a reference P-transposon (shown as a solid vertical line). Coordinates of the reference transgenic insertions are shown in Additional file 2 Table S1. Position and orientation of underlying genes (as in FlyBase Genes r. 5.12) is indicated below as horizontal blocks and arrows. Y axis shows combined percentages of 0.5 kb long DNA segments found associated with a particular class of proteins (n = 20). Color-coding for such classes is indicated below. Vertical dashed lines delimit the regions most probably corresponding to interbands.