The spindle shows remarkable diversity, and changes in an integrated fashion, as cells vary over evolution. Here, we provide a mechanistic explanation for variations in the first mitotic spindle in nematodes. We used a combination of quantitative genetics and biophysics to rule out broad classes of models of the regulation of spindle length and dynamics, and to establish the importance of a balance of cortical pulling forces acting in different directions. These experiments led us to construct a model of cortical pulling forces in which the stoichiometric interactions of microtubules and force generators (each force generator can bind only one microtubule), is key to explaining the dynamics of spindle positioning and elongation, and spindle final length and scaling with cell size. This model accounts for variations in all the spindle traits we studied here, both within species and across nematode species spanning over 100 million years of evolution.

中文翻译：

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化学计量相互作用解释了线虫一亿年进化过程中的纺锤体动力学和尺度


随着细胞在进化过程中发生变化，纺锤体表现出显着的多样性和整体变化。在这里，我们为线虫第一有丝分裂纺锤体的变化提供了机制解释。我们结合定量遗传学和生物物理学来排除纺锤体长度和动力学调节的广泛模型，并确定作用于不同方向的皮质拉力平衡的重要性。这些实验使我们构建了一个皮质拉力模型，其中微管和力发生器（每个力发生器只能结合一个微管）的化学计量相互作用是解释纺锤体定位和伸长以及纺锤体最终长度和延伸动力学的关键。随单元格大小缩放。该模型解释了我们在此研究的所有纺锤体性状的变化，包括物种内和跨越 1 亿年进化的线虫物种之间的变化。