Fig. 2. gp210-dsRNA-mediated depletion or mutation affects lamin depolymerization and chromosome mixing. (A) Confocal still images from time-lapse recordings of the first zygotic division of control(RNAi) (top) and gp210(RNAi) (bottom) embryos expressing YFP-lamin and GFP–β-tubulin (not recorded). Recordings were synchronized relative to the onset of anaphase. Abnormal YFP-lamin remaining during mitosis (arrowheads) and the formation of twinned daughter nuclei (arrows) are indicated. Bar, 10 µm. (B) Confocal still images from time-lapse recordings of the first zygotic division of gp210(RNAi) embryos expressing GFP-histone H2B show that the maternal and paternal chromosomes remain separated during mitosis (arrowheads) and are packaged in two distinct nuclei after mitosis. Bar, 5 µm. (C) TEM image of a twinned nucleus (arrows) derived from a two-cell-stage gp210(tm2320) embryo entering metaphase. Condensed chromosomes (top panel) are partially aligned but physically separated by two NEs (arrowheads). Bar, 500 nm. At a higher magnification (bottom panel), spindle microtubules (short arrows) are visibly aligned towards the chromosomes, and the nucleoplasmic and cytoplasmic components are mixed, indicated by the ribosomes (black dots) seen in the nucleoplasm. Note the stacked membrane segments of the NE (long arrows). Bar, 100 nm. (D) gp210(RNAi) embryos expressing YFP-lamin (green in merge) were processed for the immunolocalization of NPCs with mAb414 (red in merge) and NUP153 (not in merge) together with chromatin (blue in merge) and observed by epifluorescence microscopy. The remaining lamins of the ongoing (arrowheads) or the previous cell division (arrows) are indicated. Bars, 2 µm.