Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.
Centre National de la Recherche Scientifique, Illkirch, France.
Elife. 2017 Jun 14;6:e25078. doi: 10.7554/eLife.25078.
Fluid flows generated by motile cilia are guiding the establishment of the left-right asymmetry of the body in the vertebrate left-right organizer. Competing hypotheses have been proposed: the direction of flow is sensed either through mechanosensation, or via the detection of chemical signals transported in the flow. We investigated the physical limits of flow detection to clarify which mechanisms could be reliably used for symmetry breaking. We integrated parameters describing cilia distribution and orientation obtained in vivo in zebrafish into a multiscale physical study of flow generation and detection. Our results show that the number of immotile cilia is too small to ensure robust left and right determination by mechanosensing, given the large spatial variability of the flow. However, motile cilia could sense their own motion by a yet unknown mechanism. Finally, transport of chemical signals by the flow can provide a simple and reliable mechanism of asymmetry establishment.
纤毛运动产生的流动在脊椎动物左右组织者中引导身体左右不对称的建立。已经提出了竞争假说：流动的方向是通过机械感觉来感知的，或者是通过检测在流动中运输的化学信号来感知的。我们研究了流动检测的物理极限，以阐明哪些机制可用于可靠地打破对称性。我们将描述斑马鱼体内纤毛分布和方向的参数整合到流动产生和检测的多尺度物理研究中。我们的结果表明，鉴于流动的空间变异性很大，不动纤毛的数量太少，无法通过机械感觉可靠地确定左右。然而，运动纤毛可以通过未知的机制来感知自身的运动。最后，流动中的化学信号的传输可以提供一种简单而可靠的不对称建立机制。
