Movie S2.

A simulation of Xist spreading during X inactivation. Time-evolution from particle-based reaction diffusion simulations demonstrate Xist RNA spreading through the core and surface of the X chromosome. White chain, X chromosome; magenta, X inactivation center (XIC); red, bound Xist RNA; light blue, diffusing Xist RNA. Newly transcribed Xist RNA particles (blue) originate from the X inactivation center (magenta) and diffuse around the exterior of the chromosome, near the surface of the chromosome and through the interior of the chromosome. Simultaneously, the X chromosome undergoes a large, experimentally based conformational re-organization from the active to the inactive state. Xist RNAs bind to experimentally determined Xist binding sites (red). At time = 7 days, Xist RNA has covered the majority of measured Xist binding sites, including those in the interior.