Figure 2.

DNase I digestion patterns obtained when chicken erythrocyte chromatin is digested in whole nuclei. (A and B) 8% polyacrylamide gel in TBE: (A) with 7 M urea; (B) without urea. (C) 2% agarose gel in glycine buffer. Nuclei were digested with increasing amounts of DNase I (10, 30, 100 and 300 U/mg DNA) on ice for 50 min at pH 6.0 (lanes a–d), at pH 6.5 (lanes e–h) and at pH 7.0 (lanes i–l). (A) Lane oligo, digestion pattern obtained when tri- and tetranucleosomes containing H1/H5 histones were digested with DNase I (taken from 23). mar, restriction marker pAT/HpaII; mn, micrococcal nuclease digest of the same nuclei.