Figure 4.

A series of confocal (a–c) and corresponding phase contrast (d–f) images of a live PAM cell expressing GFP-lamin A as it progresses from late telophase through early G1. The numbers in the top left hand corner refer to the times after the metaphase to anaphase transition. (a and b), In late telophase, lamin A remains uniformly distributed throughout the cytoplasm, except for the region containing the chromosomes. 5 min later (b and e), the majority of fluorescence is localized within daughter cell nuclei and the cytoplasmic fluorescence is greatly reduced. The overall pattern of nucleoplasmic fluorescence appears punctate. This pattern appears more obvious 58 min later in both daughter cells (c and f). Bar, 10 μm. Nontransfected PAM cells were fixed and prepared for indirect immunofluorescence with lamin A/C antibody. Early G1 daughter cells were identified by their overall morphology and the presence of a midbody using phase contrast (not shown). The confocal image of G1 cells shows primarily nucleoplasmic staining with relatively little lamin A/C staining in the cytoplasm or in the region of the nuclear lamina (g). GFP-lamin C shows a similar pattern as GFP-lamin A in early G1 (h, compare with c). The differences between B- and A-type lamins in early G1 distribution are seen in doubly transfected cells expressing CFP-laminB1 (blue) and YFP-laminA (green, i). Lamin A is found throughout the nucleoplasm and lamin B1 exclusively at the rim, but there is some overlap at the rim of the two proteins. Bars, 10 μm.