Nematic structures contribute to robust zygotic polarization in <i>C. elegans</i>

The useful part

by Michiel Vanslambrouck, Jef Vangheel, Ella Linxia Müller, Bart Smeets, Pierre Gönczy, Rob Jelier The C. Its strikingly patterned cortex features thick F-actin bundles and myosin foci, contractile nematic structures that drive characteristic surface ruffles. Approximately 30 min after fertilization, symmetry breaks near the sperm-contributed centrosomes, typically at the presumptive posterior pole, and is marked by local downregulation of contractility.

How it works

• elegans zygote polarization that represents the actin bundles and myosin foci of the cortex as a network of stiff contractile filaments.
• This initiates a cortical flow that polarizes the cell and enables PAR proteins to establish anterior and posterior domains.
• While biochemical mechanisms maintaining these domains are well understood, the mechanical role of cortical architecture in polarization remains unclear.
• We find that compressive flow aligns actin bundles in the anterior domain and generates anisotropic tension perpendicular to the flow direction.
• Although this alignment is not essential for polarization when symmetry breaking occurs at the pole, it contributes to this process when symmetry breaking occurs laterally.

Details worth keeping

elegans zygote is a powerful model for asymmetric cell division. We developed a three-dimensional (3D) mechanical model of C.