Abstract

ABSTRACT Structures resembling nuclei but depleted of protein may be released by gently lysing cells in solutions containing non-ionic detergents and high concentrations of salt. These nucleoids sediment in gradients containing intercalating agents in a manner characteristic of DNA that is intact, supercoiled and circular. The concentration of salt present during isolation of human nucleoids affects their protein content. When made in 1·95 M NaCl they lack histones and most of the proteins characteristic of chromatin; in 1·0 M NaCl they contain variable amounts of histones. The effects of various treatments on nucleoid integrity were investigated.