Live imaging of motile cilia to investigate left-right symmetry breaking in zebrafish embryos
Willy Supatto (LOB, École polytechnique)
In vertebrate embryos, cilia-driven fluid flows are guiding left-right body symmetry breaking within the left-right organizer (LRO). To investigate the generation and sensing of flows, it is required to quantify cilia biophysical features in 3D and in vivo . In the zebrafish embryo, the LRO is called the Kupffer’s vesicle (KV) and is a spheroid shape cavity, which is covered with motile cilia distributed at its surface and oriented in all directions of space. This transient structure varies in size and shape during development and from one embryo to the other. As a consequence, the experimental investigation of cilia properties is challenging. It requires quantifying cilia features in vivo and in 3D and combining the data from different embryos to compare one embryo to the other and perform statistical analyses.To reach this goal, we devised an experimental workflow combining live 3D imaging using multiphoton microscopy, image processing, and data registration to quantify cilia biophysical features, such as cilia density, motility, 3D orientation, or length. We integrated such experimental features obtained in vivo into a fluid dynamics model and a multiscale physical study of flow generation and detection. This strategy enabled us to demonstrate how cilia orientation pattern generates the asymmetric flow within the KV . In addition, we could investigate the physical limits of flow detection to clarify which mechanisms could be reliably used for body axis symmetry breaking . Finally, we discovered the distribution of cilia orientation is asymmetric within the KV . Importantly, these results suggested that the asymmetric force detection could result from the cilium being sensitive to its own motion. Together, this work sheds light on the complexity of left-right symmetry breaking and chirality genesis in developing tissues.
 From cilia hydrodynamics to zebrafish embryonic development. Supatto & Vermot, Current Topics in Developmental Biology 2011
 Physical limits of flow sensing in the left-right organizer. Ferreira et al, eLife 2017
 Chiral cilia orientation in the left-right organizer. Ferreira et al, Cell Reports, in press