Katerina Ragkousi

We can now properly credit to @swinburnelab.bsky.social 🤩 Welcome to Bluesky! 🧪

"10/10 would morph-a-gen"
the motto for this year's Dev Bio class at Amherst College.

for the love of #development and #embryology
@socdevbio.bsky.social

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...

Had the pleasure of working with @mohannad-dardiry.bsky.social to rethink what it means to develop for life. Many thanks to @dev-journal.bsky.social! @embl.org #LifelongDevSI

The evolutionary origins of synaptic proteins and their changing roles in different organisms across evolution Nature Reviews Neuroscience - Recent studies have shed further light on the evolutionary origins of chemical synapses, In this Review, Colgren and Burkhardt explore how ancient proteins were...

First neurons didn’t appear overnight. We trace their roots to ancient secretory cells - showing how lifestyle & behavior shaped the evolution of first synapses.🧠🌊 #Evolution #Neuroscience

Our latest in @natrevneuro.nature.com
Link: rdcu.be/eMX3E

@jeffcolgren.bsky.social @msarscentre.bsky.social

Our most recent study shows that stem cells in Schmidtea mediterranea do not rely on physical contacts or fixed structures to maintain their identity and regenerative potential.

@stowersinstitute.bsky.social @cp-cellreports.bsky.social @vilcekfoundation.bsky.social
www.cell.com/cell-reports...

A toolkit for testing membrane-localising tags across species Transgenic markers and tools have revolutionised how we study cells and developing organisms. Some of the elements needed to construct those tools are universally applicable (e.g. fluorescent proteins...

How can we see the cells that make up a living organism? Membrane-localising tags can drive fluorescent proteins to the cell's outer membrane, making their outlines visible. But the tags don't work well in all organisms. How do you find one for your species of interest? 🧵

Check our latest preprint

🚨 Late preprint alert!
Why do biological process rates scale nonlinearly with temperature, deviating from the straight line on an Arrhenius plot? The key may lie in their inherent complexity!

More in thread and here: doi.org/10.1101/2025...

Figure 7 - Model for the gradual loss of cellular health in the absence of SMEDWI-1. (A) In wild-type stem cells, transcripts that are not coding or are mis-assembled with protein co-factors are routinely recognized and degraded. In the absence of SMEDWI-1, this selection process is defective, and aberrant RNAs can accumulate in the cells. Over time, this leads to a reduction in correctly assembled ribonuclear protein complexes (RNPs) such as the signal recognition particle (SRP). (B) The SRP functions to guide ribosomes that translate secreted proteins to the endoplasmic reticulum to continue protein translation and allow for appropriate folding and transport of the protein product. If such a ribosome is not correctly relocated, the protein product is released in the cytoplasm and marked for degradation together with the mRNA that produced it. Alternatively, the protein product may escape degradation and accumulate in the cytoplasm as a protein that is prone to misfolding and aggregation.

Enhanced RNA quality control maintains long-term regenerative ability in planarians.

Read this #LifelongDevSI #OA Research Article by Michael Zelko, Josien C. van Wolfswinkel and colleagues:

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

Latest from ours: www.cell.com/cell-reports...

This is two stories in one: a case study/cautionary tale on developing genetic tools in new organisms, and the first hint at a gene regulatory network for choanoflagellate multicellular development (which turn out to involve a Hippo/YAP/ECM loop!) A 🧵

Phenotype rescue upon Zic4 and Gata3 double knockdown. (A,B) Maximum projection confocal images of oral (A) and aboral (B) ends of animals after GFP RNAi (control), Zic4 or Gata3 RNAi, and Zic4+Gata3 RNAi. DNA in cyan, peroxidase activity in magenta and Nematocilin in orange. Panels on the right show magnifications of boxed areas on the left. Scale bars: 100μm. Note the ectopic peroxidase staining in tentacle tips upon Zic4 RNAi, and ectopic Nematocilin staining adjacent to the foot upon Gata3 RNAi, as well as rescue of both phenotypes in the double knockdown. (C) Percentage of animals with ectopic peroxidase staining in tentacles upon Zic4 KD and double KD. (D) Percentage of animals with ectopic Nematocilin staining adjacent to the foot in Gata3 KD and double KD. For examples of strong and partial phenotypes refer to Fig. S6. Data in G and H shown for n animals pooled from at least two independent replicates. ***P<0.001 (Fisher's exact test). (E,F) Schematic of proposed model for controlling the choice between basal disk and battery cell fate in Hydra. At the oral pole, Wnt signaling (black dot) activates Zic4 (orange) expression and thus basal disk identity. Without it, Gata3 dominates at the opposite end, leading to basal disk fate establishment (E). Experimentally depleting one of the factors results in ectopic cell fate acquisition at the opposite body end (F).

Hydra body axis balance: a fight between two transcription factors

This Research Highlight showcases the work from Jaroslav Ferenc, Marylène Bonvin, Panagiotis Papasaikas, Jacqueline Ferralli, Clara Nuninger and Charisios D. Tsiairis:

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

We knew that cnidarians have stunning regenerative capacities. But the molecular and cellular mechanisms underlying the self-organization of gastruloids of Nematostella surprised us. A story of cell sorting and Notch signaling. Please check out the work of Sanjay's PhD work: doi.org/10.1101/2025...

Finally, the excellent postdoc work of Emmanuel Haillot is out, where he dissected the integration of Wnt, MAPK and Notch signaling in defining mesoderm and endoderm identities in the diploblast Nematostella. Strikingly similar to sea urchins. www.nature.com/articles/s41...

Inés Fournon Berodia presents in front of an audience. She is wearing a black blazer and a white shirt. The slide on the screen has a black background, and reads "Hallmarks of epithelial cell extrusion". Below the title, a schematic of an epithelium, and the following text in bullet points: "Mitogen Activated Protein Kinase (MAPK)", "Facilitate extrusion" and "Protect surrounding cells"

Ines Fournon Berodia smiles widely, holding in place on her head a customized graduation hat.

Congratulations Dr. Fournon Berodia @inesfournon.bsky.social 🎉🤩 We are very proud of Inés for successfully defending her PhD thesis conducted in the @prhsteinmetz.bsky.social lab. Thank you to opponents @ragkousik.bsky.social & @levayerr.bsky.social for insightful discussions 👏

Thank you!

Depletion of a neural cell adhesion molecule disrupts both epithelial and germ layer identity in sea anemone embryos Assembly of cells into epithelial layers marks the early steps of tissue organization and embryonic development in most animals. Although several conserved proteins are known to be essential for epith...

our unexpected results on the importance of a neural cell adhesion molecule in sea anemone epithelialization and gastrulation are just posted in the following preprint.

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

A host organelle integrates stolen chloroplasts for animal photosynthesis Sea slugs steal foreign chloroplasts and store them in specialized organelles that facilitate photosynthesis and eventual digestion to mediate starvation resistance.

A host organelle integrates stolen chloroplasts for animal photosynthesis: Cell www.cell.com/cell/fulltex...

Mark your calendars for May 18-22, 2026- in Roscoff, Brittany, for the next iteration of the Developmental Biology Conference Jacques Monod!

We thought we were just studying mesoglea biogenesis…Turns out Nematostella has been hiding a sophisticated backup pressure valve! Work driven by the talented PhD student Soham Basu! @embl.org‬ www.biorxiv.org/content/10.1...

The anti-neural role of BMP signaling is a side effect of its global function in dorsoventral patterning In Bilateria with centralized nervous systems (e.g. in vertebrates or arthropods), the minimum of the BMP signaling activity gradient defines the position of the central nervous system. BMP-dependent ...

The last part of @paulknabl.bsky.social 's PhD is now available at www.biorxiv.org/content/10.1...
Paul showed that BMP signaling is active in the diffuse nervous system of the sea anemone Nematostella and the box jellyfish Tripedalia. Moreover, suppression of BMP signaling in Nematostella leads...

It's #MicroscopyMonday, so let's take a peek into the 🔬
This movie was taken by Shinya Inuoe, who built the polarizing microscope that allowed scientists to see mitotic spindle fibers live for the first time.

Dr. Inuoe premiered his research at MBL.

Cartoon of autonomous and light-modulated spwning cycles in Clytia IZ-D

Intriguing findings from our Sendai collaborators Ruka Kitsui and Ryusaku Deguchi. While C. hemispherica spawns at dawn, Clytia IZ-D species spawns at dusk. This is not triggered by dark but, unexpectedly, by light-mediated extension of an autonomously-running 20h cycle. doi.org/10.1101/2025...

Epithelial polarization by the planar cell polarity complex is exclusively non–cell autonomous For cells to polarize collectively along a tissue plane, asymmetrically localized planar cell polarity (PCP) complexes must form intercellular contacts between neighboring cells. Yet, it is unknown wh...

How many cells do you need to establish PCP? The magic number is 3! Beautiful work by Lena Basta in Danelle Devenport's lab. Happy to have contributed. www.science.org/doi/10.1126/...

Happy to announce our latest paper! A fresh look at the sponge Aggregation Factor, a glycoprotein complex involved in self-recognition and adhesion. Previously thought to be sponge-specific, we report compelling structural links with proteins found in all animals! www.pnas.org/doi/10.1073/...

Congratulations to you and everyone involved!

β-catenin-driven endomesoderm specification is a Bilateria-specific novelty - Nature Communications Lebedeva et al. show that unlike Bilateria, the embryo of the cnidarian Nematostella specifies its endomesoderm in the β-catenin-negative domain. In contrast, subsequent β-catenin-dependent axial patt...

Tanya's @tclebedeva.bsky.social paper on endomesoderm specification in the beta-catenin-negative area of the Nematostella embryo is out! www.nature.com/articles/s41...

🧬 February's most-read Genetics paper looks at how #RNA travels between cells to control genes across generations #epigenetics: buff.ly/ulMGsBH

Have a paper people should see? See what our Editors look for: buff.ly/HmuOWDp

One week left to apply!

Thrilled to see #choanoflagellates on the cover of Science Advances🤩. Our latest work "Electrical signaling and coordinated behavior in the closest relative of animals" out now. Link: www.science.org/doi/10.1126/... 👏 @jeffcolgren.bsky.social @msarscentre.bsky.social

Mitotic polarity oscillation promotes epithelial tumor progression Mitosis of epithelial cells requires a transient loss of epithelial polarity [[1][1]–[5][2]]. However, the nature of this mitotic polarity oscillation and its functional consequences for epithelial de...

by Jeyanathan et al from the Ulrich Tepass lab.
www.biorxiv.org/content/10.1...