Chromatin depletion or decondensation occurs at various positions of the 45S rDNA repeat unit.

<p>Pictures in the left panel represent three different lesions at various positions in the 45S rDNA region. Arrows indicate lesion sites. Pictures in the right panel are kymograms showing the intensity of the signals for the hybridization sites. The horizontal axis is the length of one chromosome; the vertical axis is the gray level which measures the intensity of the fluorescent dye and signals. The green line represents the hybridization site and signal intensity, and the red line shows PI-stained chromosomes.