%0 Journal Article %A PEOPLES, OLIVER P. %A WHITTAKER, PAUL A. %A PEARSTON, DOUGLAS %A HARDMAN, NORMAN %T Structural Organization of a Hypermethylated Nuclear DNA Component in Physarum polycephalum %D 1985 %J Microbiology, %V 131 %N 5 %P 1157-1165 %@ 1465-2080 %R https://doi.org/10.1099/00221287-131-5-1157 %I Microbiology Society, %X Digestion of Physarum polycephalum nuclear DNA using the restriction endonuclease HpaII generates two components, distinguishable on the basis of their molecular size. The high-molecular-weight, HpaII-resistant component, which accounts for 20% of the DNA, contains a fivefold greater concentration of 5-methylcytosine residues than the low-molecular-weight HpaII-digested fraction. Segments of hypermethylated (M+) DNA are largely composed of a single, long, highly repeated sequence, and this major element is sometimes associated with other less highly repetitive sequences in the M+ DNA fraction. Restriction mapping of cloned Physarum M+ DNA segments, and Southern blot analysis of genomic DNA using subcloned segments of M+ DNA as a probe, provide evidence for sequence variation within different copies of the dominant highly repeated element, and possibly the other associated repeats in M+ DNA, and additionally that almost complete tandemly repeated copies of the major repeat are found in some M+ DNA segments. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-131-5-1157