A. Ligation reactions and supercoiling. Reactions were prepared as described Experimental Procedures. The position of linearized plasmid (lane 1, input), bacterial supercoiled (lane 2) and dimers is indicated. The various topomeric forms of supercoiled plasmid (the result of deposition of nucleosomes on the template) are not resolved well in this gel without chloroquine, and appear as a slight smear (lanes 6, 9, 10). B. Assay of chromatin assembly. Nucloesomes assembly was carried out on 2 μg of Bluescript plasmid as described in Methods. Each band corresponds to the addition of one nucleosome, which decreases the linking number. These gels are representative of two different experiments.