Anaïs Bailles

Congratulations @philipschoene.bsky.social on defending his Master’s thesis on the supremacy of mechanics in Hydra regeneration from aggregates of dissociated cells. Expertly guided by @anaisbailles.bsky.social. #experiment and #theory #LoPaTs @mpi-cbg.de @poldresden.bsky.social #stuffthatmatters

Thanks a lot to @elisecutts.bsky.social for nicely highlighting and putting in context our article! It was very interesting to discuss together, notably about the analogies between the emergence of order in Hydra and other physical phenomena.

Thank you Mathieu! 😁

Dear Fly Community, In May 2025, the NIH terminated all grant funding to Harvard University, including the NHGRI grant that supported FlyBase. This grant also funded FlyBase teams at Indiana University (IU) and the University of Cambridge (UK), and as a result, their subawards were also canceled. The Cambridge team has secured support for one to two years through generous donations from the European fly community, emergency funding from the Wellcome Trust, and support from the University of Cambridge. At IU, funding has been secured for one year thanks to reserve funds from Thom Kaufman and a supplement from ORIP/NIH to the Bloomington Drosophila Stock Center (BDSC). Unfortunately, the situation at Harvard is far more critical. Harvard University had supported FlyBase staff since May but recently denied a request for extended bridge funding. As a result, all eight employees (four full-time and four part-time) were abruptly laid off, with termination dates ranging from August to mid-October depending on their positions. In addition, our curator at the University of New Mexico will leave her position at the end of August. This decision came as a shock, and we are urgently pursuing all possible funding options. To put the need into perspective: although FlyBase is free to use, it is not free to make. It takes large teams of people and millions of dollars a year to create FlyBase to support fly research (the last NHGRI grant supported us with more than 2 million USD per annum). To help sustain FlyBase operations, we have been reaching out to you to ask for your support. We have set up a donation site in Cambridge, UK, to which European labs have and can continue to contribute, and a new donation site at IU to which labs in the US and the rest of the world can contribute. We urge researchers to work with their grant administrators to contribute to FlyBase via these sites if at all possible, as more of the money will go to FlyBase. However, we appreciate that some fu…

https://wiki.flybase.org/wiki/FlyBase:Contribute_to_FlyBase Our immediate goals are: 1. To maintain core curation activities and keep the FlyBase website online 2. To complete integration with the Alliance of Genome Resources (The Alliance). Integration with the Alliance is essential for FlyBase’s long-term sustainability. For nearly a decade, NHGRI/NIH has supported the unification of Model Organism Databases (MODs) into the Alliance, which we aim to achieve by 2028. Therefore, securing bridge funding to sustain FlyBase over the next three years is crucial for successful integration and the long-term access to FlyBase data. At present, our remaining funds will allow us to keep the FlyBase website online for approximately one more year. Beyond that, its future is uncertain unless new funding is secured. We will, of course, continue pursuing additional grant opportunities as they arise. Given the uncertainty of future NIH or alternative funding sources, we are relying on the Fly community for support. Your contributions will directly help us retain the staff needed to complete this transition and to secure ongoing fly data curation into the Alliance beyond 2028. We at FlyBase are incredibly grateful for the outpouring of support from the community during this challenging time. Your encouragement has strengthened our resolve and underscores how vital this resource remains to Drosophila research worldwide. Sincerely, The FlyBase Team

The community of Drosophila researchers is amazing, mutually supportive and collaborative. Right now a key resource for our community, @flybase.bsky.social , is threatened by the cancellation of its NIH grant and is seeking community help in raising short term funds 1/n 🧪 please share

This is a question for #LISH25 :)

Our beautiful Hydra made the cover!!! 😍😍😍
An experiment performed by Pavel Mejstrik with a HCR protocol by @giuliaserafini.bsky.social, @paveltomancak.bsky.social lab @mpi-cbg.de
Actin fibers in blue, nuclei in orange.

And in case you were wondering if Hydras look like their mythological counterparts, the regenerated aggregates can indeed have multiple heads! And their number is scaling with the size of the aggregate.

You can find more movies here, and do not miss the supplementary figures: tinyurl.com/3wz4mavb. Thanks to the people who contributed to this work, Giulia Serafini, Heino Andreas, Chris Zechner, Carl Modes, @paveltomancak.bsky.social and @mpi-cbg.de. A big thank to the Hydra community for the help 💚

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 anisotropic stretch but delayed by supracellular (smectic-like) fibers. Wnt head organizers would only play a role later. (7/9)

What about stretch? We constrained the aggregates in agarose except for a hole. The tissue protrudes inside the hole, and the resulting stretch has a fast effect on actin alignment in the whole aggregate. Importantly, Wnt head organizers were not yet present in the protrusion. (6/9)

We mechanically perturbed the aggregate by changing topology ('skewer') and geometry ('sausage'). 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 line defects. This suggests that local cell-cell interactions drive the transition from disorder to order. (4/9)

First, we quantified the emergence of order over days using analogies with liquid crystals. Rotational symmetry is broken. Surprisingly, translation symmetry is also partially broken. This smectic behavior is associated with the formation of supracellular actin fibers. (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)

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)

Anisotropic stretch biases the self-organization of actin fibers in multicellular Hydra aggregates | PNAS During development, groups of cells generate shape by coordinating their mechanical properties through an interplay of self-organization and prepat...

Publication @pnas.org www.pnas.org/doi/10.1073/...

Stretching the immortal Hydra Dresden researchers show how cells can create a new organism from scratch by coordinating their mechanical properties.

Stretching the immortal Hydra. Publication by @paveltomancak.bsky.social group with Carl Modes @mpi-cbg.de & @zechnerlab.bsky.social shows how cells can create a new organism from scratch by coordinating their mechanical properties. @anaisbailles.bsky.social @pnas.org www.mpi-cbg.de/news-outreac...

To recognise and celebrate @svobodalab.bsky.social's pivotal contribution to Woodstock Bio2 + Night Science, #TCTeAC, I am starting this "What Petr Svoboda did at Woodstock?" thread. If you were there - #contribute and #retweet.

"Petr Didn’t Submit an Abstract. #TCTeAC Submitted to Him."

The Extinction of Truth Or, a Colossal Pile of Bullshit

Updated a broken link in my substack post about the
#ColossalBio #DeExtinction #DisInformation campaign – dire wolves are still extinct.

open.substack.com/pub/devoevom...

#LoPaT @anaisbailles.bsky.social bringing up the wonders of #Hydra, #physics, disorder to order transition and tissue mechanics to #TCTeAC