A. pG5ML plasmid was relaxed by Topoisomerase I and incubated in egg extract for 1 or 5 hours, as indicated. Reactions were treated with 1U of MNase for 0, 4, 12, 20, or 30 minutes and the DNA was run on an agarose gel and stained with EtBr. Nucleosomal sized fragments were readily apparent in the 1 hour incubation but not the 5 hour incubation.
B. pG5ML plasmid was relaxed by Topoisomerase I and incubated in egg extract for 1 hour at 25, 50, 75, 100, or 125 ng DNA / μl of egg extract, as indicated. Reactions were treated with 1 or 2 units of MNase and DNA was run on an agarose gel and stained with EtBr.