Thanh Vuong-Brender, in Michel Labouesse’s team¹, has developed an experimental and interdisciplinary methodology combining physics and biology to study the mechanisms involved in the embryonic elongation of the nematode Caenorhabditis elegans. Indeed, at the end of its development, the C. elegans embryo undergoes major shape changes, including a four-time increase in length along the head-tail axis in the absence of cell migration or division.

The team has collaborated with Martine Ben Amar, a physicist at the École Normale Supérieure to show how myosins and the actin cytoskeleton act together mechanically to allow the embryonic elongation (the former is a molecular motor related to the one inducing muscle contraction, whereas the latter is a polymer network giving mechanical properties to cells).

Using laser ablation to map the mechanical forces applied along the embryo, the researchers have shown that myosin motors, active in a row of cells on each side of the embryo, induce mechanical constrictions along the circumferential axis, producing an effect similar to a boa constrictor tightening its prey. Adjacent to myosin-rich cells, the dorsal and ventral epidermal cells create solid actin bundles along the circumference, limiting growth in this direction. Thus, by generating forces or becoming more or less flexible, the different cell-types work together to promote the elongation of the embryo.

These results help to better understand the mechanisms involved in the shaping of C. elegans, and morphogenesis in general. The study², published in eLife on February 9^th, has been featured on the INSB (CNRS) website.

1. Team Mechanical forces behind tissue morphogenesis
2. The interplay of stiffness and force anistropies drive embryo elongation