Figure 4

Defective sister chromatid separation and aberrant nuclear sizes and shapes upon loss of Cap-G. (A) Selected images from a timelapse recording of mitotic divisions at gastrula stages analyzed in Tg [H2A::GFP] transgenic embryos. cap-g morphant embryos display defective sister chromatid separation and abnormal chromatid morphology during anaphase. (B) Selected images from a timelapse analysis of mitotic divisions within the ventricular zone of the neural tube at 32 hpf. Progression from prometaphase, when condensed chromosomes are visible, to anaphase is significantly delayed in cap-g^s105 mutants. (C) Transverse vibratome sections through retinae counter-stained with propidium iodide reveal aberrant nuclear sizes and morphologies within cap-g^s105 mutants at 3 dpf. The strict retinal layering into inner INL and PRL is not recognizable. Red asterisk indicates decondensed nucleus with chromatid bridge/non-disjunction event. Similarly, the non-neural tail region of cap-g^s105 mutants contains cells with incomplete separation of chromatids (red asterisk). (D) In the wild-type retina, most nuclei in the photoreceptor layer have an elongated appearance. In cap-g^s105 mutant or cap-g^s105 mutant/p53 morphant retinae, most PRL nuclei fail to elongate. Data represent mean ± SD, n ≥ 115 for each retinal layer and genotype; **, p < 0.01; ***, p < 0.005. (E) Representative histograms from FACS analysis of propidium idodide stained nuclei suspensions. Whereas at 72 hpf most cells in the wild-type are diploid (2C; 1C = haploid genome equivalent), cap-g^s105 mutants harbor an increased fraction of cells with a genomic content >2C, especially in the tetraploid range (4C).