Katerina Ragkousi
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ragkousik.bsky.social
Katerina Ragkousi
@ragkousik.bsky.social
160 followers 260 following 8 posts
Biologist and Assistant Professor studying how cells build animals and how animals organize cells. Sea anemone (Nematostella) lab at Amherst College.
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ragkousik.bsky.social
Katerina Ragkousi @ragkousik.bsky.social · Feb 12
"Lateral cell polarization drives organization of epithelia in sea anemone embryos and embryonic cell aggregates"
www.pnas.org/doi/10.1073/...
Lateral cell polarization drives organization of epithelia in sea anemone embryos and embryonic cell aggregates | PNAS
One of the first organizing processes during animal development is the assembly of embryonic cells into epithelia. Common features unite epithelial...
www.pnas.org
Reposted by Katerina Ragkousi
aikmi.bsky.social
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
October 31, 2025 at 11:24 AM
Reposted by Katerina Ragkousi
pawelburkhardt.bsky.social
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
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...
rdcu.be
October 27, 2025 at 6:48 PM
Reposted by Katerina Ragkousi
planaria1.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...
October 19, 2025 at 7:56 PM
Reposted by Katerina Ragkousi
michalis-averof.bsky.social
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
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...
www.biorxiv.org
October 23, 2025 at 8:16 AM
Reposted by Katerina Ragkousi
nikitaphysics.bsky.social
🚨 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...
October 22, 2025 at 10:29 AM
Reposted by Katerina Ragkousi
dev-journal.bsky.social
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/...
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.
October 21, 2025 at 12:34 PM
Reposted by Katerina Ragkousi
thibautbrunet.bsky.social
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 🧵
October 5, 2025 at 10:35 AM
Reposted by Katerina Ragkousi
dev-journal.bsky.social
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/...
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).
September 16, 2025 at 10:27 AM
Reposted by Katerina Ragkousi
ulrichtechnau.bsky.social
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...
September 11, 2025 at 4:16 PM
Reposted by Katerina Ragkousi
ulrichtechnau.bsky.social
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...
August 29, 2025 at 9:04 PM
Reposted by Katerina Ragkousi
msarscentre.bsky.social
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 👏
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.
August 26, 2025 at 2:09 PM
ragkousik.bsky.social
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...
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...
www.biorxiv.org
August 6, 2025 at 5:27 AM
ragkousik.bsky.social
A host organelle integrates stolen chloroplasts for animal photosynthesis: Cell www.cell.com/cell/fulltex...
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.
www.cell.com
June 26, 2025 at 4:01 AM
Reposted by Katerina Ragkousi
bardinlab.bsky.social
Mark your calendars for May 18-22, 2026- in Roscoff, Brittany, for the next iteration of the Developmental Biology Conference Jacques Monod!
bardinlab.bsky.social Bardin Lab @bardinlab.bsky.social · May 29
Coming back in 2026- a Jacques Monod Conference in Roscoff centered on Developmental Biology! This edition will be:
“Developmental regulation: from molecular to ecological niches” @lionlchristiaen.bsky.social and I hope to see you there! Info and dates coming soon.
June 13, 2025 at 7:19 AM
Reposted by Katerina Ragkousi
aikmi.bsky.social
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...
May 28, 2025 at 10:45 AM
Reposted by Katerina Ragkousi
genikhovich.bsky.social
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...
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 ...
www.biorxiv.org
June 9, 2025 at 8:57 AM
Reposted by Katerina Ragkousi
mblscience.bsky.social
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.
May 5, 2025 at 8:53 PM
Reposted by Katerina Ragkousi
clytia-vlfr.bsky.social
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...
Cartoon of autonomous and light-modulated spwning cycles in Clytia IZ-D
May 5, 2025 at 2:09 PM
Reposted by Katerina Ragkousi
eposfai.bsky.social
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/...
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...
www.science.org
March 22, 2025 at 1:47 AM
Reposted by Katerina Ragkousi
scottnichols.bsky.social
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/...
PNAS
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...
www.pnas.org
December 18, 2024 at 7:15 PM
Reposted by Katerina Ragkousi
genikhovich.bsky.social
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...
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...
www.nature.com
March 13, 2025 at 11:26 AM
Reposted by Katerina Ragkousi
elife.bsky.social
🧬 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
March 14, 2025 at 9:01 PM
Reposted by Katerina Ragkousi
arnausebe.bsky.social
One week left to apply!
arnausebe.bsky.social Arnau Sebé-Pedrós @arnausebe.bsky.social · Jan 8
Monod Conference "Origin of metazoans": fossils, genomes, cell biology, gene regulation, development, and more.

Join us in Roscoff for an exceptional speaker line-up and stunning venue!

🗓️Abstract deadline: March 4.

Register and share!
www.insb.cnrs.fr/fr/origin-me...
Origin of metazoans
Roscoff (Bretagne), France, June 16-20, 2025Deadline for application: March 4, 2025
www.insb.cnrs.fr
February 26, 2025 at 12:39 PM
Reposted by Katerina Ragkousi
pawelburkhardt.bsky.social
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
January 8, 2025 at 7:49 PM
ragkousik.bsky.social
by Jeyanathan et al from the Ulrich Tepass lab.
www.biorxiv.org/content/10.1...
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...
www.biorxiv.org
February 19, 2025 at 3:19 AM