Data from: Dynamics of cilia length in left–right development

Reduction in the length of motile cilia in the zebrafish left–right organizer (LRO), also known as Kupffer's vesicle, has a large impact on left–right development. Here we demonstrate through genetic overexpression in zebrafish embryos and mathematical modelling that the impact of increased motile cilia length in embryonic LRO fluid flow is milder than that of short cilia. Through Arl13b overexpression, which increases cilia length without impacting cilia beat frequency, we show that the increase in cilium length is associated with a decrease in beat amplitude, resulting in similar flow strengths for Arl13b overexpression and wild-type (WT) embryos, which were not predicted by current theory. Longer cilia exhibit pronounced helical beat patterns and, consequently, lower beat amplitudes relative to WT, a result of an elastohydrodynamic shape transition. For long helical cilia, fluid dynamics modelling predicts a mild (approx. 12%) reduction in the torque exerted on the fluid relative to the WT, resulting in a proportional reduction in flow generation. This mild reduction is corroborated by experiments, providing a mechanism for the mild impact on organ situs.斑马鱼左右组织者（left–right organizer, LRO，又称库普弗囊泡Kupffer's vesicle）内的运动纤毛（motile cilia）长度缩短，会对胚胎左右轴发育造成显著影响。本研究通过斑马鱼胚胎的基因过表达实验与数学建模，证实胚胎LRO内运动纤毛长度增加对流体流动的影响相较于短纤毛更为温和。本研究借助不影响纤毛摆动频率的Arl13b基因过表达来增加纤毛长度，发现纤毛长度增加与摆动振幅降低相关，使得Arl13b过表达组与野生型（wild-type, WT）胚胎的流体流动强度相近——这一结果无法通过现有理论预测。相较于野生型胚胎，更长的纤毛呈现出更为显著的螺旋摆动模式，因此摆动振幅更低，这一现象源于弹性流体动力学形状转变。针对长螺旋纤毛，流体动力学建模预测其对流体施加的扭矩相较于野生型会出现约12%的小幅降低，进而导致流体流动产生能力成比例下降。这一微小降幅得到了实验结果的验证，为“纤毛长度增加对器官左右不对称性（organ situs）影响温和”这一现象提供了机制解释。