FIG. 9.

Nucleosome spacing is reduced in mutants with extensive reductions in total H1. (A and B) Thymus nuclei from wild-type (WT) and H1⁰ H1c H1e triple-null (KO) mice. (A) Nucleosome repeat ladder obtained by micrococcal nuclease digestion of thymus nuclei as described in Materials and Methods. Lane 1 contains marker (M) DNA. Chromatin from the H1-deficient mutant nuclei migrates faster than that from wild-type nuclei, as illustrated by the asterisks at the pentanucleosome bands. (B) Plot of nucleosome number versus DNA length for thymus chromatin shown in panel A. Symbols show the data points, and lines are the linear regressions of the data points, which indicate a ΔNRL of 9 bp for these samples (see Materials and Methods for details). (C) Relationship between changes in H1 content and NRL. Superscripts: α, results of separate experiments (each comparison was done with different wild-type and knockout mice); #, from data in Table 2; *, data shown in panels A and B. ND, not determined.