See the intricate worlds of parasites and algae — March’s best science images The month’s sharpest science shots, selected by Nature’s photo team.

Our ExM Atlas of eukaryotes is moving along with more and more images coming in - some featured in nature last month!
Culture we’re provided by @ccapoban.bsky.social & Julius Lukeš during visits last year

www.nature.com/immersive/d4...

I'm happy to present our new tool, EpiCure, a napari plugin to ease correction of segmentation and tracking of epithelia movies, developed in @devstempasteur.bsky.social

Happy to share the heroic effort of @gaellel.bsky.social to reduce our segmentation pain through EpiCure (Epithelial Curation), a napari plugin easing the curation of epithelial segmentation developed with several groups of @devstempasteur.bsky.social.
www.biorxiv.org/content/10.6...
See more 👇

Many thanks to @juliaeckert.bsky.social and @onenimesa.bsky.social for all the behind the scenes work you do for running the page! 🙏

Go check out my thread about cell extrusion 🌸 at @epimechfc.bsky.social and give them a follow for more content on epithelia-related research ✨🧫

Thank you Julia! It was a pleasure and an honour contributing ❤️🪸🪼

Hello epithelia enthusiasts!

I’m @inesfournon.bsky.social and I study epithelial mechanics in sea anemones 🪼

Did you know epithelial cell extrusion had never been described outside bilaterian animals before? Well… not anymore 👀

Read ⬇️🧵1/9

Fournon-Berodia, I., Bruderer, N., Christiaen, L., & Steinmetz, P. R. (2025). Epithelial cell extrusion underlies starvation-induced cell loss in a sea anemone. bioRxiv, 2025-12. #EpithelialMechanics
buff.ly/VJknuUe

Congrats everyone 🤩✨🥳

A widely used RNA assay labels the wrong molecules in several model organisms After a routine experiment raised suspicions, Steinmetz group researchers joined forces with collaborators to highlight the limitations of a commonly used RNA labeling product.

New paper out in @bmc.springernature.com 🤩👏 A routine 5-ethynyl uridine (EU) RNA labeling experiment in a sea anemone turned into detective work for @malinkjosavik.bsky.social, @ktgarschall.bsky.social & @prhsteinmetz.bsky.social 🕵️‍♀️

Imaging spotlight: U-ExM atlas of microbial eukaryotes - FocalPlane Imaging spotlight: U-ExM atlas of microbial eukaryotes - News

🔬🔦Our Imaging spotlight from @hiralshah.bsky.social & team highlights their U-ExM atlas of planktonic eukaryotes, including details on how you can explore this wonderful resource. Plus, check out Hiral’s top tips on getting started with expansion microscopy.
focalplane.biologists.com/2026/01/20/i...

Another #notTHECover unfortunately.

But this gorgeous, Tron-like vibe, drawn by the amazing @munafomarzia.bsky.social for our recent #ExM work with @gautamdey.bsky.social & @centriolelab.bsky.social will still be printed out in the lab.

Read here: www.cell.com/cell/fulltex...

Thank you Ira ♥️

Thank you very much ☺️

Thank you Gautam! ☺️

Viva!

They are indeed wonderful! Thank you Omaya 🤩

Thank you James 🥹♥️

Thank you!

Thank you so much Ruth ♥️🥹

Together, our results show that the key hallmarks of epithelial cell extrusion are evolutionarily ancient, predating the last common ancestor of sea anemones, flies, and vertebrates🪼🪸✨ 5/5

Finally we found active TOR-signalling within rosettes and late apoptotic extruding cells to be phagocytosed by neighbouring rosette cells suggesting a link between cell extrusion and nutrient recycling ♻️ 4/5

We also developed an image-based machine learning pipeline 🤖 for automated cell segmentation and rosette ID using Cellpose as the basis. With this we found that extrusion density increases and epidermal cell density decreases during starvation 3/5

We also showed conserved active ERK signalling in the rosette cells and confirmed the apoptotic nature of the extruding cells. As previously studied in flies🪰 and mammals 🧫 2/5

Extrusion occurs via a rosette-like structure 🌸 in which a central ring is formed and translocates as we showed with a newly CRISPR/Cas9 generated β-Catenin-mOrange2 🚨 knock-in line 1/5

Thrilled to share the preprint from my PhD! 🥳 Where I characterised epithelial cell extrusion in a sea anemone
🔗 www.biorxiv.org/content/10.6...
Big thanks to my supervisor @prhsteinmetz.bsky.social and coauthors @noahbruderer.bsky.social @lionlchristiaen.bsky.social at🇳🇴 @msarscentre.bsky.social ⬇️🧵

Top: The phylogenetic position of Nematostella and localization of Vasa2 +/Piwi1+ cells within the juvenile polyp body plan. (A) Simplified phylogenetic tree highlighting the phylogenetic position of the sea anemone Nematostella vectensis and other animal taxa relevant for this study. All animal silhouettes are licensed under CC0,1.0 Universal Public domain and taken from https://www.phylopic.org. (B–D) Schematics showing the localization of Vasa2+/Piwi1+ cells in a juvenile polyp, depicted in longitudinal (B) or cross-section (C, D). (E) Schematic representation of the multipotent, Vasa2+/Piwi1+ stem/progenitor cell population and a simplified summary of their germinal and somatic progeny. (F) Schematics of cell cycle phases, highlighting the incorporation of EdU during S-phase (black line) and the phosphorylation of Histone H3 (pH3+) during metaphase. Bottom: Confocal image of two Vasa+/Piwi+ stem-like cells in the inner epithelial folds of the sea anemone Nematostella vectensis. Immunolabelling of mOrange2-Piwi1 fusion protein (yellow) in a transgenic knock-in line combined with nuclear stain (white). Image credit: Paula Miramón-Puértolas.

How do animals with lifelong growth modulate cell #proliferation? @eudaldpascual.bsky.social @ktgarschall.bsky.social @prhsteinmetz.bsky.social show that starvation induces G1/G0 #CellCycle arrest in Vasa2+/Piwi1+ #SeaAnemone cells; cycle re-entry is TOR-dependent @plosbiology.org 🧪 plos.io/48J2o6P

Inés Fournon Berodia, a young woman wearing a beige jacket and burgundy pants, presents a slide on a screen. It reads "Meet the sea anemone Nematostella vectensis" and shows pictures of pink sea anemones half-buried in sand.

Ruth Styfhals, a young woman wearing a green sweater, presents a slide on a screen in front of an audience. The audience is seen from behind at the forefront of the picture. The slide reads "Ctenophores: the oldest animals?" on a bright blue background. On the the left-hand side of the slide, we can see a photograph of a ctenophore or comb jelly - a gelatinous, transparent marine animal.

Congratulations to @inesfournon.bsky.social and @ruthstyfhals.bsky.social on their amazing talks at the very first BIO-Early Career Community Conference at @unibergen.bsky.social ✨ We are proud to support this fantastic initiative that brought our local community of young scientists together 👏

Congrats to all authors! 🎉 Very happy to see this paper out where I had the chance to finish off a small part on this crazy story on what happens if you kill all the neurons and then chop off the head of a sea anemone 🪸👾

Ectopic head regeneration after nervous system ablation in a sea anemone Via genetic ablation of neurons, Mazloumi Gavgani et al. show that the nervous system is essential for defining axial polarity during whole-body regeneration in the sea anemone Nematostella vectensis.

Our paper on the role of neurons in Nematostella head regeneration is now out at @currentbiology.bsky.social Big thank you to all collaborators, it was a pleasure!

Ectopic head regeneration after nervous system ablation in a sea anemone: Current Biology www.cell.com/current-biol...