Figure 2.

Stable higher order chromatin arrangements in interphase nuclei of living RPE-1 cells. (A) Activation of paGFP-H4 fluorescence (green) along a prometaphase chromosome yields distinct chromosome-territories in the two daughter nuclei. The whole chromosome complement is visualized mRFP-H2B (red). (B) Simple nuclear rotation along an axis perpendicular to the growth surface indicated by positional changes of the paGFP fluorescent area (for more complex rotational movements compare Fig. 3). (C) Various patterns of paGFP-H4 fluorescence are stably maintained in interphase nuclei during the whole observation period (up to 30 h). Images taken at the end point were corrected for simple rotational nuclear movements to ease the comparison with the pattern recorded at the start point. Signal blurring indicates locally constrained chromatin movements (compare Movie S1). (D) A cross-like paGFP-H4 fluorescence pattern induced in telophase is maintained throughout interphase into the next prophase (36 h). Labeling of neighboring prophase chromosomes indicates that the stripes of paGFP-H4 fluorescence induced at telophase covered neighboring CTs. (E) Fluorescent paGFP-H4 stripes are stably maintained through S-phase. Proliferating Cellular Nuclear Antigen (PCNA) tagged with mRFP reveals the typical change of the PCNA S-phase pattern.