Figure 1From: DNA moves sequentially towards the nuclear matrix during DNA replication in vivoProcedure for mapping the position of loop DNA sequences relative to the NM. A) Nucleoids prepared from freshly isolated primary rat hepatocytes were incubated with DNase I so as to progressively digest the loop DNA. Nucleoid samples with partially digested NM-bound DNA, as shown in the drawing and fluorescent micrographs (C) were used for PCR amplification of target sequences. The amplicons were run in agarose gels and scored as present (+) or absent (-) by an image analysis software as a function of nucleoid-sample digestion time (C) and the corresponding topological zones relative to the NM defined by the kinetics of nucleoid-DNA digestion. B) Drawing illustrating the local topology along a typical supercoiled DNA loop that correlates with both sensitivity to DNase I and distance relative to the NM thus defining topological zones relative to the NM.Back to article page