Very happy to share the first article from my postdoc work in the Tomancak lab! https://t.co/0gmwblw1Wb. We studied the self-organization of actin in aggregates made from Hydra cells. Thread below (1/9)

We are back this Thursday with two fascinating talks on morphogenesis and pattern formation!🌟 @NerurkarLab and @AnaisBailles will share their latest insights. Mark your calendar so you don’t miss it! 👇👇 🗓️ Nov 21, 12:30 EST / 18:30 CET / 17:30 UTC 🕥

🔬✨ New insights into tissue regeneration! Our study uncovers a novel mechanochemical mechanism in Hydra, revealing how mechanical forces and Wnt signaling work together to create intricate tissue patterns. #Cnidarians #Hydra #Biology #Regeneration

Thanks to the people who contributed to this work @GiuliaSerafin12 , Heino, @zechnerlab , @carldmodes (team smectics), @PavelTomancak and the Tomancak team. Also, a big thank to the Hydra community for help and discussions!

Embryos hatch in a configuration similar to our stretch experiments: they break the shell on one side and stretch outside this hole. Actin is indeed aligned with the direction of the stretch. The mechanism we uncovered could also provide robustness to the embryo patterning. (9/9)

We think this is a great example of how mechanics impacts and potentially drives self-organization and the emergence of order in collectives of cells and how analogies from physics can help understand it. Of course, ‘what about embryos?’ asked Pavel. (8/9)

Altogether, this suggests that the ordering of actin in aggregates happens through cell-cell interaction and is favored by the anisotropic stretch but impaired by supracellular (smectic-like) fibers. Wnt pattern would only play a role later. (7/9)

What about stretch? We constrained the aggregate in agarose except for a hole. Anisotropic stretch inside the hole has a fast effect on actin alignment, which propagates to the center of the aggregate. Importantly, the alignment does not match the Wnt expression pattern! (6/9)

We mechanically perturbed the aggregates by changing topology (skewers) and geometry (sausages). Topological changes alone do not significantly bias the actin orientation. Geometry has an indirect effect on actin orientation but is not associated with curvature anisotropy. (5/9)

Measurement of the nematic (orientation) order parameter in space and time showed growing ordered domains and lines of defects. This argues against a gradient-driven mechanism and in favor of local cell-cell interactions driving the transition from disorder to order. (4/9)

First, we quantified the emergence of order over days. Rotational symmetry is broken. Surprisingly, translation symmetry is also partially broken. This smectic behavior is associated with the formation of supracellular actin fibers, which stabilize defects at late stages. (3/9)

Hydra is not only immortal but also can self-organize a whole organism from a clump of thousands of cells. In these aggregates, actin polarity is completely lost in cells and is re-established de novo. We studied how the transition from disorder to order happens. (2/9)

My first scientific communication event in German 🤪thankfully @jogirstmair was there to translate 😁

Pierre Ronceray and I are recruiting a PhD student to study non-equilibrium fluctuations in developing fly embryos. The position is through @centuri_ls in Marseille, France and will begin in October 2024. Applications due Feb 15th. More details here: https://t.co/sPbT3BXeaK. #phd

Check out our latest preprint on how Hydra cells regenerate missing parts. You might need to update your textbook knowledge on regeneration…

Please RT! Welcoming applicants with applied math/CS background for a PhD project with @ClaudioCollinet. Exploiting large language model of intracellular dynamics to decipher how thousands of flux events shape cells and organs. Apply until Feb 15th at https://t.co/In3litogQg

Please RT. We are looking for a PhD student in physics or CS to develop modeling of stochastic branching dynamics in dendritic neurons in collaboration between @JFRupprecht_OM and our group🤩. More info 👉 https://t.co/sfAsgYR9mn Please reach to us by email if you are interested.

Very nice to see this work out! After studying a tissue scale myosin wave, we wanted to go more into the subcellular details. Claudio's beautiful experiments feature all the cool players: actin, integrins... and I am happy I could contribute with quantifications!

It’s out! Learn how a self-organized wave of adhesion, contractility and de-adhesion is mechanically regulated at the cellular scale. https://t.co/zNvCereToG