标题： 减数分裂II卵母细胞中稳定纺锤体定位的水动力学机制 显示英文标题

标题： Hydrodynamic mechanism for stable spindle positioning in meiosis II oocytes

摘要： 细胞质流动，即细胞内持续的流体流动，会引发细胞内运输，在基本的生物过程中起着关键作用。 在等待受精的减数分裂II期小鼠卵母细胞（发育中的卵细胞）中，负责将遗传物质分配到细胞中的纺锤体必须在靠近细胞皮层（与细胞膜结合的薄肌动蛋白网络）的位置保持数小时。 然而，伴随这种稳定定位的细胞质流动似乎会破坏纺锤体的位置稳定性。 在这里，通过数值和分析建模的结合，我们揭示了一种新的、流体力学机制，用于在皮层帽下方稳定纺锤体定位。 我们表明，这种稳定性关键取决于纺锤体的大小和皮层的主动驱动，并证明稳定的纺锤体定位可以纯粹由细胞质流动对纺锤体施加的流体力学吸力引起。 我们的发现表明，局部流体力学力足以稳定纺锤体，解释了对扰动的鲁棒性，不仅包括垂直于皮层的方向，还包括平行于皮层的方向。 我们的结果阐明了细胞质流动在哺乳动物减数分裂中的重要性。 显示英文摘要

摘要： Cytoplasmic streaming, the persistent flow of fluid inside a cell, induces intracellular transport, which plays a key role in fundamental biological processes. In meiosis II mouse oocytes (developing egg cells) awaiting fertilisation, the spindle, which is the protein structure responsible for dividing genetic material in a cell, must maintain its position near the cell cortex (the thin actin network bound to the cell membrane) for many hours. However, the cytoplasmic streaming that accompanies this stable positioning would intuitively appear to destabilise the spindle position. Here, through a combination of numerical and analytical modelling, we reveal a new, hydrodynamic mechanism for stable spindle positioning beneath the cortical cap. We show that this stability depends critically on the spindle size and the active driving from the cortex, and demonstrate that stable spindle positioning can result purely from a hydrodynamic suction force exerted on the spindle by the cytoplasmic flow. Our findings show that local fluid dynamic forces can be sufficient to stabilise the spindle, explaining robustness against perturbations not only perpendicular but also parallel to the cortex. Our results shed light on the importance of cytoplasmic streaming in mammalian meiosis.