Micrococcal Nuclease-Southern Blot Assay: II. Capillary Transfer and Hybridization

INTRODUCTIONThis is the second phase of a two-part assay for exploring whether an endogenous control region of interest is assembled into nucleosomes or is devoid of nucleosomes. This assay can also be used to determine if nucleosomes are similarly positioned at the locus in every cell within a population. In this second part of the assay, the restricted genomic DNA is separated by agarose gel electrophoresis and stained with ethidium bromide, resulting in a ladder of bands corresponding in size to multiples of the nucleosome core plus linker (~200 bp). To determine whether a DNA fragment of interest is nucleosomal, the genomic DNA is subjected to Southern blot analysis. If a probe derived from the DNA fragment hybridizes to the ladder of nucleosomal bands, the fragment may indeed be assembled into nucleosomes.