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Posts by Katrina Velle

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Microbial eukaryotes keep challenging assumptions about eukaryotic cell and genome biology.

Our upcoming workshop explores the frontier of protist genomics and how it shapes cell biology, ecology and evolution.

Please save the date! Talks, posters and ECR events

Websites and details coming soon

4 months ago 94 38 1 0

Are you interested in cytoskeleton and looking for a postdoc position? I will be advertising positions in the new year but happy to chat in person if you are attending ASCB @ascbiology.bsky.social in Philadelphia. Just drop me a line.

4 months ago 34 33 0 1

Just under a month left—apply by December 5 through the link on my website!

5 months ago 16 11 0 0
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🚨Our collaboration with @centriolelab.bsky.social & @gautamdey.bsky.social is out today in @cp-cell.bsky.social
We show that #Expansion #Microscopy is a broad-spectrum modality for Euks, enabling 3D phenotypic maps rooted to phylogeny.
#ProtistsOnSky #SciComm #SciSky

www.cell.com/cell/fulltex...

5 months ago 214 98 15 11
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Very excited that my final postdoctoral work is now online in Cell @cellpress.bsky.social.

www.sciencedirect.com/science/arti...

Using 16 (!) cryo-EM structures, we uncovered how the three proteins coronin, cofilin and AIP1 work together to rapidly disassemble actin filaments.

6 months ago 151 41 6 5

Incredible video, incredible work. This is a huge step forward in understanding both actin severing, and more broadly, how actin binding proteins change filament architecture and thus drive re-modeling 🧪

6 months ago 21 4 1 0
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Happy #MicrosCreepy season!

6 months ago 12 1 0 0
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And a flagellate swimming! (In ficoll to slow it down- it’s doing its best!)

6 months ago 1 0 1 0
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Yup! Here’s an amoeba crawling:

6 months ago 4 0 1 1
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I have been slacking on the #microscreepy season! Thanks for reposting!

6 months ago 1 1 2 0

Thanks for reposting!

6 months ago 0 0 0 0

They are both Naegleria gruberi— they are normally amoebae, but can transiently transform into a flagellate as a stress response

6 months ago 2 0 1 0
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PhD or Master's position available for Fall 2026!

Interested in how actin drives cell crawling, eating, dividing, or osmoregulation? What about pathogenesis of a brain-eating amoeba? Or eukaryotic evolution? If so, apply through my website: katrinavelle.wixsite.com/science/cont...
Please share!

6 months ago 48 28 1 5
Poster with a picture of the speaker, Pablo Saez, advertising his talk: Decision Making during cell migrations. Abstract: Moving cells navigate inside living tissues often encountering obstacles and junctions, where their path branches into alternative directions of migration. This is the case of cells moving on top or within blood vessels, which often bifurcate into branches. Cells have diverse migratory strategies that differentially rely on the adhesion to the substrate. Cells that undergo mesenchymal migration are highly dependent on the adhesion to the substrate, and when facing bifurcations are forced to coordinate the adhesion and detachment of the competing branches. Recent studies showed how the decision is made -to keep or retract a branch and choose a new direction- when there is bias: open versus dead-end, differences in pressure, presence/absence of a chemoattractant. However, much less is know about how cells decide a new direction when the decision is unbiased. Similarly, it is poorly understood how migrating cells coordinate membrane dynamics during branching to maintain a good trade-off between microenvironmental exploration and migratory efficiency. Here, we use in vitro live-cell imaging using different levels of complexity, and advanced image analysis to analyze the response of migrating cells when facing symmetric junctions, and extreme branching when cells simultaneously face several bifurcations. We found that actin and membrane dynamics play a key role to choose a new direction path in both cases i) when cells face a single junction (Ron et al. 2024), and ii) when cells exhibit high levels of branching because they face several junctions at the same time (Liu et al.). In addition, we found that migrating immune cells have a fine tune regulation of branching in order to coordinate surveillance and migration. These results shed light on the mechanisms by which cells resolve unbiased junctions and branching during cell migration.

Poster with a picture of the speaker, Pablo Saez, advertising his talk: Decision Making during cell migrations. Abstract: Moving cells navigate inside living tissues often encountering obstacles and junctions, where their path branches into alternative directions of migration. This is the case of cells moving on top or within blood vessels, which often bifurcate into branches. Cells have diverse migratory strategies that differentially rely on the adhesion to the substrate. Cells that undergo mesenchymal migration are highly dependent on the adhesion to the substrate, and when facing bifurcations are forced to coordinate the adhesion and detachment of the competing branches. Recent studies showed how the decision is made -to keep or retract a branch and choose a new direction- when there is bias: open versus dead-end, differences in pressure, presence/absence of a chemoattractant. However, much less is know about how cells decide a new direction when the decision is unbiased. Similarly, it is poorly understood how migrating cells coordinate membrane dynamics during branching to maintain a good trade-off between microenvironmental exploration and migratory efficiency. Here, we use in vitro live-cell imaging using different levels of complexity, and advanced image analysis to analyze the response of migrating cells when facing symmetric junctions, and extreme branching when cells simultaneously face several bifurcations. We found that actin and membrane dynamics play a key role to choose a new direction path in both cases i) when cells face a single junction (Ron et al. 2024), and ii) when cells exhibit high levels of branching because they face several junctions at the same time (Liu et al.). In addition, we found that migrating immune cells have a fine tune regulation of branching in order to coordinate surveillance and migration. These results shed light on the mechanisms by which cells resolve unbiased junctions and branching during cell migration.

🚨 TLM Online Seminar Series - 08.10.25 | 16:00 UK
Pablo Sáez: "Decision-making during cell migration"

Please repost & to attend online please register to our 📧for the zoom link: lists.cam.ac.uk/sympa/subscr...

6 months ago 19 5 0 0
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Cell Migration Seminars Cell Migration Seminars every Tuesday at 16:00 BST.

If anyone ever wants to brush up on a lot of cell migration concepts don't forget we have several wonderful scientists who have given talks previously in cell migration seminars. I find it so comforting to go look at old videos, maybe someone else who will do as well!!
youtube.com/@cellmigrati...

6 months ago 43 10 1 2
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Arp2/3-mediated bidirectional actin assembly by SPIN90 dimers Nature Structural & Molecular Biology - Liu et al. show that SPIN90 dimerizes and binds two Arp2/3 complexes to nucleate two bidirectional actin filaments and the dimerization domain is...

And now for something completely different @tianyang22.bsky.social & #YanCao uncover of how SPIN90 dimers activate Arp2/3 to nucleate bidirectional linear actin filaments. Great collaboration with @romet-jegou-lab.bsky.social & @carolynmoores1.bsky.social #Cryo-EM #Arp2/3 rdcu.be/eGoH4

7 months ago 51 15 4 2
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”Please inhibit responsibly: Natural and synthetic actin toxins as useful tools in cell biology”

I had a lot of fun going down different actin inhibitor rabbit holes with @onishilab.bsky.social on this perspective!

www.molbiolcell.org/doi/10.1091/...

www.molbiolcell.org/cms/10.1091/...

7 months ago 35 13 0 1
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@fritzlaylin.bsky.social et al. propose a simple way to highlight both experimental #reproducibility & cell-to-cell variation, while avoiding pitfalls common in analysis of cell biology data rupress.org/jcb/article/...

📕 Reproducibility & Best Practices in Cell Biology: rupress.org/jcb/collecti...

7 months ago 9 7 1 0
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📢📢Hiring 2 Research Assistants & 2 Postdocs at Emory University in Atlanta to study cytoskeletal biophysics/biochemistry. Please RT.

RAs: great for recent bachelor's/master's in Physics/Bio/Chem/Biochem. Email CV and interests to shekhar@emory.edu.

More info: www.shekharlab.org

7 months ago 36 32 0 1

Our latest preprint on the role of the Arp2/3 complex in mitotic entry is now available @biorxiv. This work was done by Dhanya Kalathil, a very talented postdoc in my lab. The story started in 2019 when we were investigating the role of branched actin in cytokinesis. 1/

7 months ago 35 13 1 0
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The Origin and Diversification of Mitochondria Moving beyond the simplistic view of mitochondria as the power house of the cell, Roger et al. present the immense diversity of mitochondria and mitochondrial functions across eukaryotes, and bring th...

Feeling mitochondrially challenged lately?

Here are two classic reviews on #mitochondria that should help.

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

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

7 months ago 120 44 3 5
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How did life get multicellular? Five simple organisms could have the answer Single-celled species that often stick together in colonies have researchers rethinking the origin of animals.

For some three billion years, unicellular organisms ruled Earth. Then, around one billion years ago, a new chapter of life began

go.nature.com/3JyRV4S

7 months ago 131 49 4 5

I'm growing (pun intended) pretty fond of the idea. Maybe at some point this semester!

7 months ago 1 0 0 0

Hey @arzaf.bsky.social how about a side project? 😄

7 months ago 2 0 2 0

New preprint online!

So much fun working on this project, thank you @centriolelab.bsky.social and @dudinlab.bsky.social for embarking me on this one!

Hopefully HAK-actin will become your best companion for actin staining U-ExM expanded samples.

7 months ago 12 4 1 0
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#FluorescenceFriday

#Mitochondria, powerhouse of the #cell were labeled (cyan) and it's possible to visualize how they reach *every* corner to provide energy.

All recorded under the microscope @cellcommlab.bsky.social

#scicomm #sciencesky #microscopy #organelles @focalplane.bsky.social 🧪🔬

10 months ago 106 24 1 2
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Who needs BioRender when you have #MSPaint?

www.cell.com/cell/abstrac...

10 months ago 13 2 0 0
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Bethesda Declaration — STAND UP FOR SCIENCE Support NIH Staff Now!

Today, @nihfellowsunited.bsky.social staff sent a powerful letter to the NIH Director outlining serious concerns about the agency’s direction. Thousands have already signed in support—add your name. – Mary Munson, ASCB President www.standupforscience.net/bethesda-dec...

10 months ago 125 49 3 3

Glad to see some scientific society leadership stepping up to endorse the #BethesdaDeclaration

10 months ago 37 7 1 0
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An amoeba movie I made: "hungry" #protistsonsky #amoeba

10 months ago 28 7 1 0