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Figure 7 | Epigenetics & Chromatin

Figure 7

From: Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci

Figure 7

Failure of ‘autosomal Barr body’ formation consistent with a Xi correlated Barr body after inducing an autosomal Xist transgene. (A) Immuno-RNA-FISH against Xist RNA (green) and RNAP II (red) at indicated time points after Xist induction. RNAP II is located in close proximity to Xist RNA foci within an extended ‘Xist territory’ at day 1.5. Persistence of RNAP II signals within a widespread ‘Xist territory’ up to day 10 with only slight chromatin compaction visible at days 6 and 10. Scale bars: 5 μm (left column), insets 1 μm (right column). (B) Only small changes in DAPI intensity classification of the emerging ‘Xist-territory/autosomal Barr body’ with respect to the entire nucleus 3 and 6 days after Xist induction, plotted as over/underrepresentation. (C) Variable manifestations of ‘Xist territories’ 10 days after Xist induction. The top and middle panels exemplify Xist RNA spreading into decondensed chromatin marked by RNAP II, while the bottom panel exemplifies a ‘Xist territory’ with large exclusion of RNAP II. Scale bars: 5 μm, inset 1 μm. (D) Number and volume distributions of discernible Xist RNA foci in tr36 ESCs at day 10 of Xist induction (n = 15 nuclei), for comparison shown together with XX ESCs at day 9 of differentiation (see Figure 6). DAPI, 4',6-diamidino-2-phenylindole; ESC, embryonic stem cell; FISH, fluorescence in situ hybridization; RNAP II, RNA polymerase II; Xi, inactive X chromosome; Xist, X inactive specific transcript.

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