Joel Marthelot

Capillary interactions drive the self-organization of bacterial colonies - Nature Physics Bacteria tend to live in thin layers of water on surfaces. Now the capillary forces in these layers are shown to help organize the bacteria into dense packs.

Dreaming of a swimming pool? Bacteria are surrounded by water! Water capillary forces organize bacterial colonies into gas, nematic streams, or droplet states. New paper @natphys.nature.com led by Matt Black and Chenyi Fei, with Ned Wingreen and Josh Shaevitz!

www.nature.com/articles/s41...

Insect X-Men: Helmets help these odd bugs sense electric fields Ability may help treehoppers distinguish friend from foe

About 3200 insect species around the world have evolved a structure on their back called a helmet.

But the appendage isn’t just for show: It allows for the detection of electric fields—perhaps helping them distinguish friend from foe. scim.ag/46xid0Y

Des étoiles dans notre intestin ! Dans une étude parue dans Nature Communications, des scientifiques montrent que, dans les cellules intestinales de souris, des filaments d’actine, co

Dans les cellules intestinales de souris, des filaments d'actines forment des structures en forme d'étoile ! ⭐

🤝 @cnrs-dr12.bsky.social @univ-amu.fr @ibdm.bsky.social

👉 Lire l'article dans @natcomms.nature.com
buff.ly/oit2wSj

Similar brain volume in phylogenetically distant species, and very different brain volumes in phylogenetically close species.

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Interestingly, in many cases close cousins can have very different brain sizes – like chimps and humans (among many others in panel c), and genetically distant species can have very similar brain sizes (panel b for examples).

Brain Surfaces of 70 primate species

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To predict the behaviour of a primate, would you rather base your guess on a closely related species or one with a similar brain shape? We looked at brains & behaviours of 70 species, you’ll be surprised!

🧵Thread on our new preprint with @r3rt0.bsky.social , doi.org/10.1101/2025...

Wound repair in plants guided by cell geometry Mathew et al. show that growth conflicts reshape cells after injury, forming rhomboidal geometries that trigger diagonal divisions. This reorients cell files to restore tapered morphology. A two-step ...

Our new paper is out!
1/14 How does an organ rebuild its shape after injury? It's not just about making new cells, but aligning them in the right direction — like bricks shaping a structure. We show that it's all driven by Cell Geometry!

www.cell.com/current-biol...

Electroreception in treehoppers: How extreme morphologies can increase electrical sensitivity | PNAS The link between form and function of an organism’s morphology is usually apparent or intuitive. However, some clades of organisms show remarkable ...

Why do treehoppers look so weird?! Our latest paper, out this week in @pnas.org, suggests a perhaps unexpected reason - static electricity ⚡ We show that treehoppers can detect the electrostatic cues of predators and that their crazy shapes may boost their electrosensitivity! doi.org/10.1073/pnas...

Have you ever thought about inflating tissues?
Or maybe quickly deflating those inflated tissues?

New #EpithelialMechanics pre-print: doi.org/10.1101/2025...
🧵 with pressure control, multiscale buckling, controlled wrinkling

Now (finally) #published @natcomms.nature.com: "A multi-tiered mechanical mechanism shapes the early neural plate" @mpipks.bsky.social @mpi-cbg.de

A great collaboration of experiment and theory to explain the tissue flows shaping the #zebrafish neural plate!

doi.org/10.1038/s41467-025-61303-1

How to turn a layer of fibroblasts into a tulip 🌷?

Check out our new pre-print on shape-programmable living surfaces.

Led by @pauguillamat.bsky.social‬

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

1/27 We have a new paper out! Turns out that snowflake yeast have been hiding a secret from us - they've evolved a (very!) crude circulatory system. Not with blood vessels or a heart, but through spontaneous fluid flows powered by their metabolism. 🧪🔬

www.science.org/doi/full/10....

In stratified fluids, small porous particles can settle faster than large ones. In linear stratification, the settling rate is set by the solute absorption rate. New predictions and experiments in our latest work out today in @pnas.org.

www.pnas.org/doi/10.1073/...

Benoit Roman (right), CNRS research scientist at PMMH and a member of the MecaWet team, has just been awarded the #CNRS Silver Medal. As a specialist in experimental mechanics involving large geometric deformations, he is recognized for his outstanding contributions to the field. Congratulations!

Our paper on hyperdisordered packing is out! Chromatophore arrangement on squid skin reveals an exotic form of disordered packing, caused by the interplay of cell insertion and surface growth journals.aps.org/prx/abstract...

New paper out in @pnas.org

We followed cells migrating along signalling gradients in 3D, and found they collectively behave as a living droplet - a self-propelling fluid that grows.

www.pnas.org/doi/10.1073/...

Jishen's Tête de Moine #onthecover of #PRL ! 🙌 a PMMH-SIMM collaboration @espciparispsl.bsky.social‬ 👉 doi.org/10.1103/Phys...

Nucleoli as biomolecular bubble tea! Congrats to former Princeton ugrad Holly Cheng (now GS @MIT) ->Holly's senior thesis work, a close collab w Roggeveen Wang & @zs-biophys.bsky.social‬ &Stone. Come for the cool movies & stay for the viscoelasticity! www.pnas.org/doi/10.1073/pnas.2407423122

You've got friends round for coffee and cake. There are seven of you. Trouble is, you've made a square cake. How do you make sure everyone receives an equal share?

Dominic has his cake and they all eat it.

Cheese Flowers Are Shaped by Friction Scraping the surface of a Tête de Moine cheese wheel produces frilly ribbons whose flower-like forms depend on the local friction.

Tête de Moine cheese is served in fan-shaped, flower-like ribbons. Researchers have found that the frilly forms arise from spatial variations in the properties of the cheese wheel from which the flowers are removed. The insight could help improve the processing of soft materials.

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

Buckling normally happens when you compress something slender, but 'tug' on a piece of crumpled paper at two points and it also buckles. Read more about how this "localized-TUG folding" occurs in many systems at: www.pnas.org/doi/10.1073/pnas.2423439122

Autonomous locomotion simply with tubes as limbs, and no brain? 🎈🤖

Yes, through physical synchronization! Our article is out today in Science (@science.org)

Article: www.science.org/doi/10.1126/...

Authors: @albertocomoretto.bsky.social, H.A.H. Schomaker, J.T.B. Overvelde

More below 🧪 ⚛️
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Déployer ses ailes : la première étape cruciale de l’insecte adulte 🪰🦋🐞 Un article grand public avec @simonhadjaje.bsky.social et édité par Elsa Couderc

www.science.org/doi/10.1126/...

How can a cell control the size of its organelles?

Excited to share a mechanism to control droplet size we recently found.

a 🧵

www.nature.com/articles/s41...

An object that shrinks as you pull it? This is physically possible! All you need is a piece of rubber with a weird shape. This is just mechanics and geometry.

This discovery reveals phenomena that defy intuition, and unlocks functionalities that could not yet be achieved in mechanical systems.

Reversible kink instability drives ultrafast jumping in nematodes and soft robots A soft jumping robot inspired by nematodes demonstrates ultrafast jumping using reversible kink instability and stiffness.

Excited to share our new work in @science.org #Robotics that shows how reversible kinks can help nematodes perform jumps 1000 times faster than you can blink! scim.ag/4iDIa1i
🧵:
Work co-led by @chemicalsunnyraj.bsky.social , @itiwari93.bsky.social and Victor Ortega-Jimenez with many other colleagues

Join us this Fall at ICTS for an advanced course on Geometry, Mechanics & the Physics of Growth: www.icts.res.in/program/Geom... Co-organized with S. Ganga Prasath & @surajshankar.bsky.social

Our new review on topological defects 🌀 in polar active matter is out on arXiv! Co-authored by Luiza Angheluta, Anna Lång, @emmalaang.bsky.social, and @stigoveboe.bsky.social. #ActiveMatter #TopologicalDefects #CollectiveBehavior
arxiv.org/abs/2504.03284

Stretch-induced endogenous electric fields drive directed collective cell migration in vivo - Nature Materials Electric fields guide collective cell migration in developing embryos of Xenopus laevis via a voltage-sensitive phosphatase.

REPOSTING this here just to officially leave "the other place"

Our work on the role of endogenous electric fields in guiding collective cell migration during #morphogenesis is out @naturematerials.bsky.social
nature.com/articles/s41...