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. Author manuscript; available in PMC: 2012 Jun 8.
Published in final edited form as: Cold Spring Harb Symp Quant Biol. 2011 Apr 5;75:453–460. doi: 10.1101/sqb.2010.75.050

Figure 6. Looping between distant sequences and complex DNA topologies can coexist with large-scale chromatin folding into linear fibers.

Figure 6

Multi-copy DHFR BAC transgenes in mouse ES cells differentiated into fibroblast-like cells (A- DAPI staining red, EGFP-lac repressor green) or mouse 3T3 (B) cells show an average of one foci of lac operator repeats per 7 BAC copies. In mouse 3T3 cells (B) and some differentiated cells both BAC (red) and lac operator sequences (green) show extensive co-localization. In contrast segregation of lac operator sequences to the sides of large-scale chromatin fibers (C) or foci (D) are seen in other cells. Models E–G correspond to the inferred folding consistent with FISH observations in B–D respectively. (Red, BAC sequence; green, lac operator repeats; blue, the path of one BAC copy).