Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604.
Curr Biol. 2011 Aug 9;21(15):1314-9. doi: 10.1016/j.cub.2011.06.052. Epub 2011 Jul 28.
Eukaryotes segregate chromosomes in "open" or "closed" mitosis, depending on whether their nuclear envelopes (NEs) break down or remain intact. Here we show that the control of the nuclear surface area may determine the choice between these two modes. The dividing nucleus does not expand its surface in the fission yeast Schizosaccharomyces japonicus, confining the mitotic spindle and causing it to buckle. The NE ruptures in anaphase, releasing the compressive stress and allowing chromosome segregation. Blocking the NE expansion in the related species Schizosaccharomyces pombe that undergoes closed mitosis induces spindle buckling and collapse in the absence of an intrinsic NE rupture mechanism. We propose that scaling considerations could have shaped the evolution of eukaryotic mitosis by necessitating either nuclear surface expansion or the NE breakdown.
真核生物在“开放”或“封闭”有丝分裂中分离染色体，这取决于它们的核膜（NE）是否破裂或保持完整。在这里，我们表明核表面积的控制可能决定了这两种模式之间的选择。在裂殖酵母 Schizosaccharomyces japonicus 中，分裂的细胞核不会扩大其表面积，而是限制有丝分裂纺锤体的生长，导致其弯曲。在后期，NE 破裂，释放出压缩应力，从而允许染色体分离。在经历封闭有丝分裂的相关物种 Schizosaccharomyces pombe 中阻止 NE 扩张会导致纺锤体弯曲和崩溃，而没有内在的 NE 破裂机制。我们提出，尺度考虑因素可能通过需要核表面扩张或 NE 破裂来塑造真核有丝分裂的进化。
