FIG. 2.

HP1-induced local compaction of the chromatin structure of the amplified chromosome region. RRE_B1 cells were transfected with EGFP-lacR-HP1α or EGFP-lacR (control) fusion constructs. 3D images were collected 48 h after transfection of large numbers of cells. 3D images were recorded; the images shown represent individual midnuclear optical sections. (A) The chromosomal array in a control nucleus transfected with EGFP-lacR occurs as an extended fibrillar structure. (B) After HP1 targeting to the chromosomal array, chromatin occurred as a row of distinct beads. The circumference of the nucleus in panels A and B is shown by the white line. (C and D) Enlargements of the chromosomal arrays in panels A and B, respectively. Bars, A and B, 0.9 μm; C and D, 0.4 μm.