Figure 3.

Procedure for mapping the position of DNA sequences relative to the NM. (A) Nucleoids prepared from freshly isolated rat primary cells were incubated with DNase I so as to progressively digest the loop DNA, obtaining a tri-phasic kinetics of digestion (B). Nucleoid samples with partially digested NM-bound DNA, as shown in the drawing and fluorescent micrographs, (C) were used for PCR amplification of target DNA sequences located along the genomic region containing members of the rat albumin gene family. The amplicons were run in agarose gels and scored as present (+) or absent (−) by an image-analysis software (A) as a function of nucleoid-sample digestion time (C).