Many cells and tissues exhibit chirality that stems from the chirality of proteins and polymers. In the C. elegans zygote actomyosin contractility drives chiral rotation of the entire cortex circumferentially around the division plane during anaphase. How contractility is translated to cell-scale chirality, and what dictates handedness, are unknown. Septins are candidate contributors to cell-scale chirality because they anchor and crosslink the actomyosin cytoskeleton. We report that septins are required for anaphase cortical rotation. In contrast, the formin CYK-1, which we found to be enriched in the posterior in early anaphase, is not required for cortical rotation, but contributes to its chirality. Simultaneous loss of septin and CYK-1 function led to abnormal and often reversed cortical rotation. Our results suggest that anaphase contractility leads to chiral rotation by releasing torsional stress generated during formin-based polymerization, which is polarized along the cell anterior-posterior axis, and which accumulates due to actomyosin network connectivity. Our findings shed light on the molecular and physical bases for cellular chirality in the C. elegans zygote. We also identify conditions in which chiral rotation fails but animals are developmentally viable, opening avenues for future work on the relationship between early embryonic cellular chirality and animal body plan.

中文翻译：

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在秀丽隐杆线虫合子的后期手性皮质旋转中，Septins和Formin具有独特的功能。

许多细胞和组织表现出手性，这种手性源于蛋白质和聚合物的手性。在秀丽隐杆线虫合子肌动球蛋白收缩力的驱动下，整个皮质在分裂后期周向围绕分割平面旋转。未知如何将可收缩性转化为细胞规模的手性，以及决定手性的因素。Septins是细胞规模手性的候选贡献者，因为它们锚定并交联了放线菌素细胞骨架。我们报告，隔壁皮质旋转需要Septins。相比之下，皮层旋转并不需要formmin CYK-1，我们发现其在后期后期富集于后部，但有助于其手性。隔膜和CYK-1功能的同时丧失会导致异常，并经常使皮质旋转逆转。我们的结果表明，后期收缩性通过释放在基于甲醛的聚合过程中产生的扭转应力而导致手性旋转，该扭转应力沿细胞的前后轴极化，并且由于肌动球蛋白网络的连通性而积累。我们的发现揭示了秀丽隐杆线虫合子中细胞手性的分子和物理基础。我们还确定了手性旋转失败但动物在发育上可行的条件，为早期胚胎细胞手性与动物身体计划之间的关系的未来工作开辟了道路。我们的发现揭示了秀丽隐杆线虫合子中细胞手性的分子和物理基础。我们还确定了手性旋转失败但动物在发育上可行的条件，为早期胚胎细胞手性与动物身体计划之间的关系的未来工作开辟了道路。我们的发现揭示了秀丽隐杆线虫合子中细胞手性的分子和物理基础。我们还确定了手性旋转失败但动物在发育上可行的条件，为早期胚胎细胞手性与动物身体计划之间的关系的未来工作开辟了道路。