Fig. 4.

Pol I, unlike Pol II, modifies nucleosome spacing at the rDNA locus. Spheroplasts from the specified strains were digested with increasing amounts of MNase (triangles), and DNA was extracted and resolved on a 1.2% agarose gel. Southern analysis by hybridization with C (A) and P (B) probes. Probe map positions are reported in the upper part of the figure. M, molecular weight markers. Black dots indicate DNA fragments derived from digestion of chromatin containing one, two, three, or four nucleosomes.