Aurélien Villedieu

Comment les filaments d'actine s'organisent à l'intérieur des cellules et des tissus vivants En utilisant la microscopie de fluorescence résolue en polarisation, les biologistes et physiciens de l'Institut Fresnel, associés à une équipe internat

#RésultatScientifique 🔎 | Comment les filaments d'actine s'organisent à l'intérieur des cellules et des tissus vivants

🔬 @institutfresnel.bsky.social 🤝 @univ-amu.fr @centralemed.bsky.social @cnrs.fr
📍 @cnrs-dr12.bsky.social

Out today. 🙏 again to everyone for this wonderful piece of work, in particular to Aurelie @aurhin.bsky.social Chase @chasebolt.bsky.social and Brent @homeobox.bsky.social. 🙏 also to the Harris lab @fish4walking.bsky.social and @neilshubin.bsky.social @biology-unige.bsky.social @college-de-france.fr

We are all super happy and proud to see our work on the function and evolution of the #cephalic #furrow published in @nature.com. Let me say a few things about the background and history of this work on the #Evolution_of_Morphogenesis (1/12)

Investigating morphogen and patterning dynamics with optogenetic control of morphogen production Morphogen gradients provide the patterning cues that instruct cell fate decisions during development. Here, we establish an optogenetic system for the…

Our latest: We developed a chemo-optogenetic system for precise spatiotemporal control of morphogen production. Using dual light + small molecule control of Sonic Hedgehog production, we recapitulated neural tube patterning in vitro & measured spread of Shh

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www.sciencedirect.com/science/arti...

Latest paper elifesciences.org/articles/107... closes an important cycle in our efforts to study regeneration: week-long recordings allow us to observe the behaviour of cells during the entire course of regeneration in a crustacean leg – bright objects in movie are fluorescent nuclei of cells. 1/6

Very happy that the first article from my postdoc work in the Tomancak lab is now published @PNAS! www.pnas.org/doi/10.1073/.... We studied the self-organization of actin in aggregates made from Hydra cells. Thread below (1/9)

Enhancer adoption by an LTR retrotransposon generates viral-like particles, causing developmental limb phenotypes - Nature Genetics Activation of an LTR retrotransposon inserted upstream of the Fgf8 gene produces viral-like particles in the mouse developing limb, triggering apoptosis and causing limb malformation. This phenotype c...

Finally out! 🥳 Our paper showing how a transposable element (TE) insertion can cause developmental phenotypes is now published @natgenet.nature.com 🧬🦠🐁
Below is a brief description of the major findings. Check the full version of the paper for more details: www.nature.com/articles/s41588-025-02248-5

If you’ve been following this account closely, you might already know methods to probe mechanics in vitro, but what about in live embryos?

I’m @amichaut.bsky.social, and I’m going to share a few great papers on this aspect of #EpithelialMechanics.

Here is what I have been up to in the lab of @stephangrill.bsky.social together with @neipel.bsky.social and many others.
Intrigued by avian left right symmetry breaking we found that a tissue-scale active torque drives chiral flow and requires mechanical coupling to the underlying tissue.

Coming out is not a one-time event - Nature Cell Biology June is the month celebrating Pride in the USA and other countries around the world to honour the Stonewall Uprising of 1969, as well as all progress and current strives claiming equal justice for mem...

🏳️‍🌈Our editor @slefkopoulos.bsky.social discussed with @jzylicz.bsky.social about the importance of celebrating Pride, representation in science, and more! Happy Pride!
Read here: rdcu.be/ewfba
bit.ly/3Uc72TO

Many thanks to Ruoheng Li and @prelights.bsky.social for featuring our preprint!

🚨 A very interesting conference on gastrulation coming up soon 🚨 Don't miss the chance to interact with these renowned speakers! Early bird deadline: July 15th

🧵Just out !
We reveal how 4 branched epithelia—mammary, lacrimal, salivary & prostate—use a conserved YAP–Notch–p63 circuit to self-organize during development & regeneration.
Here’s the story👇
authors.elsevier.com/c/1lM285Sx5g...
Work done in @frelab.bsky.social at ‪
‪ @institutcurie.bsky.social

🥳 Thrilled to share our lab's first preprint, led by our talented postdoc Justine Creff! 👩🏻‍🔬 We tackled a fundamental question: how the epithelium withstands mechanical stress at the interface of cells with distinct geometries and mechanics, such as enterocytes (E) and goblet cells (G) (1/9)

Cell-type-specific nucleotide sharing through gap junctions impacts sensitivity to replication stress in Drosophila Boumard et al. demonstrate gap-junction-dependent tissue-scale nucleotide sharing, which impacts cellular sensitivity to perturbation of nucleotide homeostasis and replication stress. Drosophila wing ...

Very happy to share our latest lab publication!
The hard work of @bboumard.bsky.social, Gwenn Le Meur and collaborators!
Cell-type-specific nucleotide sharing through gap junctions impacts sensitivity to replication stress in Drosophila: Developmental Cell
authors.elsevier.com/a/1lDFi_Yv6z...

Thanks a lot Diana !!

The effector caspases drive cell death, but their activation can often be survived, so how do cells make this decision? Our new preprint from @levayerr.bsky.social shows that instantaneous caspase activity is important, but past activation has a key role to play!

www.biorxiv.org/content/10.1...

Our results thus show that primitive streak formation is induced by NODAL activation in the posterior hypoblast. The movement of the hypoblast (which is a counter-rotating movement) is a consequence of primitive streak formation – and not a cause of it, as previously thought.

Finally, we investigated whether the anterior hypoblast could inhibit primitive streak formation, as previously thought. By grafting the anterior hypoblast onto the forming primitive streak, we could show that it does not. On the contrary, the grafted hypoblast starts to express NODAL.

In this movie, you can for example see that the full ablation of the hypoblast completely inhibits primitive streak formation, while a partial ablation that leaves a piece of posterior hypoblast on each side leads to the formation of two embryonic axes (forming conjoined twins).

Using functional analyses and tissue-recombination experiments, we confirmed that the posterior hypoblast is indeed the inducer of primitive streak formation through NODAL signaling activation.

Using HCR-RNA-FISH, we observed that the expression of NODAL, a master activator of primitive streak formation, initiates in the posterior hypoblast and then spreads to the entire posterior blastoderm.

The hypoblast thus remains in constant contact with the epiblast, which is incompatible with the idea that its movement controls primitive streak formation by locally lifting NODAL inhibition. This contradiction led us to reinvestigate the molecular mechanisms underlying primitive streak formation.

By intercalating a porous filter between the epiblast and the hypoblast, we further showed that the hypoblast requires physical contact with the epiblast to achieve counter-rotating flows. Thus, forces generated in the epiblast propagate by mechanical coupling to the hypoblast, setting it in motion.

By generating a two-color chimera, we observed that the counter-rotating flows of the epiblast and hypoblast are highly synchronized. As a result, the hypoblast and epiblast move very little in relation to each other.

We have adapted live-imaging techniques previously used to characterize tissue flows in the avian epiblast to describe, this time, tissue flows in the hypoblast. This allowed us to discover that, like the epiblast, the hypoblast exhibits counter-rotating flows (also known as Polonaise movements).

In birds and mammals, primitive streak formation is thought to occur when an anterior movement of the hypoblast (visceral endoderm in mice) lifts its inhibition on the posterior epiblast, allowing NODAL signaling activation. However, in birds, a precise description of this movement was lacking.

Live imaging and functional characterization of the avian hypoblast redefine the mechanisms of primitive streak induction In birds and mammals, the formation of the primitive streak, the hallmark of the primary axis and site of gastrulation, is thought to occur when an anterior displacement of the hypoblast (visceral end...

🚨New preprint
Glad to share my postdoc work on the role of the hypoblast in primitive streak induction! Discover how live imaging observations led us to revisit the molecular mechanisms governing embryonic axis induction
Thanks to @jeromegros.bsky.social and all co-authors!
doi.org/10.1101/2025...

Direct measurements of active forces and material properties unveil the active mechanics of early embryogenesis Despite progress in probing tissue mechanics, direct long-term measurements in live embryonic epithelia are lacking. This limits our understanding of amniote embryonic morphogenesis, which takes place...

🚨📣 New preprint alert!
Excited to share my new postdoc work on direct force and mechanical properties measurements in live embryos!
A great team effort with A. Chamolly (theory), under the supervision of F. Corson and @jeromegros.bsky.social
📄 www.biorxiv.org/content/10.1...
#devbio #mechanics

A case for broadening our view of mechanism in developmental biology ABSTRACT. Developmental biologists can perform studies that describe a phenomenon (descriptive work) and/or explain how the phenomenon works (mechanistic work). There is a prevalent perception that mo...

ICYMI: Commentary on "mechanism" in dev bio

Ozpolat et al argue for diverse approaches to mechanism - from molecular to systems level

journals.biologists.com/dev/article/...