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Wallace Marshall

@wallaceucsf.bsky.social
4.2K followers 6.6K following 632 posts

professor at UCSF, engineer turned cell biologist, wants to know how cells solve geometry problems

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Reposted by Wallace Marshall
American Society for Cell Biology @ascbiology.bsky.social · 01/09/2026
Congratulations to Wallace Marshall of UCSF, recipient of the 2026 Keith R. Porter Lecture, honoring innovative leaders advancing our understanding of cell biology. www.ascb.org/society-news/ascb-anno…
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Wallace Marshall @wallaceucsf.bsky.social · 18/08/2026
true or false: ARPA-H is just task-rabbit for biomedical researchers?
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Wallace Marshall @wallaceucsf.bsky.social · 05/08/2026
Congratulations everyone!
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Reposted by Wallace Marshall
American Society for Cell Biology @ascbiology.bsky.social · 03/08/2026
Congratulations to the 2026 ASCB Honorific Award Winners! ASCB is proud to recognize scientists whose research, mentorship, education & leadership are helping shape the future of cell biology. See all the awardees: www.ascb.org/society-news/ascb-anno…
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American Society for Cell Biology @ascbiology.bsky.social · 03/08/2026
Congratulations to the 2026 ASCB Fellows! ASCB is proud to recognize 15 scientists whose careers have advanced cell biology through outstanding research, leadership, mentorship & service. Meet the 2026 Fellows: www.ascb.org/society-news/fifteen-v…
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Wallace Marshall @wallaceucsf.bsky.social · 24/07/2026
They are sandwiches
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Stand Up for Science! @standupforscience.net · 03/07/2026
🚨 HEADS UP: If you haven't submitted a comment on the OMB proposal yet, there's still time - but it's running out! There are only 10 days left to push back against Russell Vought's attempt to give political appointees unprecedented control over federal research funding. Take Action: zurl.co/Bl59I
Graphic from Stand Up for Science urging action on a federal funding proposal. Large text reads: "10 Days Left" and "Help Us Stop Vought From Destroying American Science." A portrait of Russell Vought appears beside the U.S. Capitol. A banner along the bottom reads: "Submit a comment on the OMB proposal | Link in bio to take action." The Stand Up for Science logo appears in the top left.
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Sasha | Kai Dao 🔬 @kaidaoscience.bsky.social · 19/06/2026
8 hours. That’s all fish need to heal wounds 🐟⏱️ Why are they so fast compared to humans? I break down the science of rapid regeneration in a microscopy story 🔬 Watch here: youtu.be/Mt9f61adaP0 #FluorescenceFriday #Microscopy
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Ben Larson @blarson.bsky.social · 25/06/2026
I had a ton of fun the other day talking with @nonresidentdesi.bsky.social and @scifri.bsky.social 's Flora Lichtman and Rasha Aridi about murderous microbes and the things that we are trying to learn from them. Happy for the opportunity to bring some new awareness to the world of protists!
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Wallace Marshall @wallaceucsf.bsky.social · 16/06/2026
Which kind of makes you wonder what we are inhaling every time we take a breath
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Wallace Marshall @wallaceucsf.bsky.social · 16/06/2026
I think so - I’ve never tried the following experiment, but I’ve heard that if you just fill a bowl with sterilize springwater and let it sit out on a table somewhere in your house, after a while, a huge ecosystem will be growing in there, including not just algae, but also protists, rotifers etc
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Wallace Marshall @wallaceucsf.bsky.social · 14/06/2026
Gearing up to try that
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Reposted by Wallace Marshall
epithelial mechanics fan club @epimechfc.bsky.social · 14/06/2026
Heemskerk, I., & Streichan, S. J. (2015). Tissue cartography: compressing bio-image data by dimensional reduction. Nature methods, 12(12), 1139-1142. #EpithelialMechanics doi.org/10.1038/nmet...
doi.org
Tissue cartography: compressing bio-image data by dimensional reduction - Nature Methods
Handling and quantitative image analysis of layered tissues is greatly simplified by cartography with the Image Surface Analysis Environment (ImSAnE), as demonstrated on a variety of specimens, includ...
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Reposted by Wallace Marshall
bioRxiv Biophysics @biorxiv-biophys.bsky.social · 14/06/2026
Coupled nucleoplasmic flows and envelope expansion govern the mechanical resistance of the nucleus www.biorxiv.org/content/10.64898/20…
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Wallace Marshall @wallaceucsf.bsky.social · 13/06/2026
yeah I agree that is super interesting. i do wonder if it has to do with whether or not they are getting enough food.
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Wallace Marshall @wallaceucsf.bsky.social · 13/06/2026
but it sure makes one wonder why 200 seconds would be the threshold for ignoring vs paying attension. i really wish I knew more about what actually goes on in a pond, how often predators swim by etc.
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Wallace Marshall @wallaceucsf.bsky.social · 13/06/2026
Although it’s nit that it ignores you but the opppsite - it never learns to ignore you
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Wallace Marshall @wallaceucsf.bsky.social · 13/06/2026
Yeah man that’s EXACTLY what it means!!! 200 seconds give or take.
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Wallace Marshall @wallaceucsf.bsky.social · 13/06/2026
Happy to announce our new preprint is out, in which we analyze single-cell learning in Stentor in the frequency domain, and find that the cell behaves like a fractional-order low pass filter. www.biorxiv.org/content/10.6...
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
ok good to have that validated! they are also the best for baked, and pretty good for fried too, so honestly why do they have all the other potatoes?
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
also, they have some language about allowing only one comment per institution. so make sure to state that you are writing on your own behalf as an individual.
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
also, don;'t copy and paste someone elses's comments, they are going to use text search to group identical comments together as a single comment. make yours different.
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
this is where you go to comment: www.federalregister.gov/public-inspe... every comment will need to be read and will go into the record for future legal appeals.
federalregister.gov
Regulation for Federal Financial Assistance
The Office of Management and Budget (OMB) proposes to revise the Guidance for Federal Financial Assistance to improve government- wide policies and requirements related to the management of grants, co...
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
elizabethginexi.substack.com/p/summary-of... every US scientist needs to submit a comment. the audience is judges down the line, not the OMB itself. refer to specific sections, explain what you think about them especially if the language is unclear or contradictory. you are an expert witness
elizabethginexi.substack.com
Summary of Key Changes in OMB’s Proposed Federal Financial Assistance Rule
Russell Vought is going to destroy American Science
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Wallace Marshall @wallaceucsf.bsky.social · 06/06/2026
I drain them over the hot pan in a strainer and then leave them hanging there so they kind of steam while draining. also I only use russet potatoes not sure if that makes a difference?
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Reposted by Wallace Marshall
Dr. U. Whitcher (U. is for Bear) @yarntheory.bsky.social · 14/05/2026
Wow, this isn't just "we're banning you for 1 year," it's "future work can't be posted until it's peer-reviewed", i.e.,you can no longer use the arXiv for preprints.
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Wallace Marshall @wallaceucsf.bsky.social · 14/05/2026
you've heard alot about how cells are or are not crowded at the molecular scale, but what about at the organelle scale? in her new preprint, @marymirvis.bsky.social develops a quantitative way to ask this question in budding yeast - see her thread below www.biorxiv.org/content/10.6...
biorxiv.org
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
we don't have that result yet but I agree it could be very informative!!
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
so maybe this protein is acting as a calcium sensor to let the cell keep track of its current stimulation state or past stimulus history. right now, almost any hypothesis can be on the table. in case you missed the paper you can read it here: www.cell.com/current-biol...
cell.com
Molecular pathways for learning in the single-cell Stentor coeruleus
Rajan et al. explore the molecular basis of habituation in the unicellular organism Stentor coeruleus using a combination of pharmacological methods, proteomics, transcriptomics, and RNAi. These exper...
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
so given that it isn't a centrin, we have no reason to think it is part of the centrin-based contractile machinery. on the other hand, calcium signaling is clearly implicated in Stentor learning based on our RNAseq, proteomics, RNAi, and inhibitor studies showing that CamKII is involved.
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
the learning-related EF hand protein only has a single EF domain, unlike true centrins. Alphafold predicts that it has a large disordered domain, but that the ordered part folds into a canonical EF hand conformation that is predicted to be able to bind calcium
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
but as with so many nice ideas, this one doesn't seem to be true. Niklas Steube in @gautamdey.bsky.social lab has been studying centrin phylogeny, and he was able to show that the learning-related EF hand protein is not a centrin family member at all, but a far distance relative
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
so, if we're seeing an EF hand protein change expression during learning and recovery, and EF hand proteins of the centrin family are the machine that drives contraction, it suggests a nice hypothesis, that maybe part of learning involves modification of the centrin-based contractile machinery
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
this contraction happens in tens of milliseconds, and it is driven by cables made of a EF hand calcium binding protein called centrin. here is an image of Centrin in Stentor from Connie Yan's expansion microscopy study (see www.biorxiv.org/content/10.1...)
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
When we talk about "learning" in Stentor, we're talking about habituation to mechanical stimuli. When a Stentor cell is touched by a potential predator, the cell rapidly contracts into a ball as an escape response. if it gets contacted repeatedly, it learns to ignore the stimulus.
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
As part of her RNAseq and proteomics analysis of single-celled learning in Stentor, one of the molecules that Deepa Rajan found to be changing during learning and forgetting was an EF-hand protein. I want to tell you why we think this is interesting
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Wallace Marshall @wallaceucsf.bsky.social · 09/05/2026
reminds me of a t-shirt I designed in grad school for our dev bio program retreat, which said "Death, the final stage of development"
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Wallace Marshall @wallaceucsf.bsky.social · 08/05/2026
I need to read all your papers - I was at a meeting where there were a lot of talks about cells undergoing different kind of state transitions, and it seemed like change in volume were a common thread and honestly I had been ignorant of all that so now its time to fix that ignorance!
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Reposted by Wallace Marshall
Tamas Nagy @tamasnagy.com · 08/05/2026
My PhD work showed that resting neutrophil -> activated/prime neutrophil is a pretty big volume change needed for motility :) Super fast, only a couple minutes to swell so not like other slower changes elifesciences.org/articles/90551
elifesciences.org
Neutrophils actively swell to potentiate rapid migration
Actin-independent water influx complements actin-driven cytoskeletal forces to potentiate chemoattractant-induced migration in primary human neutrophils.
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Reposted by Wallace Marshall
Philipp Niethammer @niethammerlab.bsky.social · 08/05/2026
Basically the last 16 years of my lab‘s research is on the role of cell swelling as an alarm signal…initially dismissed by some as fish-specific response, because -obviously- only what is shown in mouse can be important 🙄
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Arthur Prat @arthurpr4t.bsky.social · 21/04/2026
The "Version of Record" of my paper with Mike Woodford is finally there. I am very glad with this paper that points to new laws of psychophysics, which we derived from a carefully considered principle of endogenous efficient coding.
elifesciences.org
Endogenous precision of the number sense
A theory of efficient coding wherein the precision of representations is endogenous, task-dependent, and prior-dependent predicts scaling laws for imprecision and is supported by numerosity perception...
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Wallace Marshall @wallaceucsf.bsky.social · 08/05/2026
and even better, the classes of genes identified in her RNAseq analysis were mirrored in a parallel proteomic analysis! so in the end, combining the two types of "omics" really does seem to have given us a new foot in the door to understanding how Stentor learns!
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Wallace Marshall @wallaceucsf.bsky.social · 08/05/2026
a big surprise in @deeparajan.bsky.social recent paper identifying molecular pathways of single-cell learning in Stentor, was how effective RNA sequencing turned out to be, revealing CamKII and EF hand proteins that were then shown by RNAi to actually play a role. www.cell.com/current-biol...
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Yanlan Mao @yanlanmao.bsky.social · 06/05/2026
This exciting paper is now out in PNAS: www.pnas.org/doi/10.1073/...
pnas.org
3D epithelial cell topology tunes signaling range to promote precise patterning | PNAS
Cell behaviors in multicellular organisms are coordinated via both diffusible molecules and by signals based on direct cell–cell contacts. The mode...
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Wallace Marshall @wallaceucsf.bsky.social · 08/05/2026
It’s starting to seem like changes in cell volume are turning up in many different cases of cell state transitions. Would be nice to collect examples.
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Meng Zhu @zhumeng123.bsky.social · 30/04/2026
Cambridge → Boston → Cambridge again: I’m thrilled to return to Cambridge(UK) to open my lab at the Gurdon Institute, University of Cambridge!🥳 (mzhulab.com) We study how dev timing shapes and being shaped by plasticity, evolution & ageing. 🚩Hiring at all levels: pls email me if interested!📩
mzhulab.com
Meng Zhu Lab
We study how development measures time and how timing matters in development, evolution and ageing.
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The Washington Post @washingtonpost.com · 03/05/2026
Up close, these tiny organisms in cow stomachs are surprisingly beautiful and evocative. Known as rumen ciliates, these microbes could be playing a more significant role in climate change than previously understood, according to new research. wapo.st/422MqS5
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SBCF @sbcf.bsky.social · 04/05/2026
Ready for #CellLaVie2026? Program & registration are live! Join us Oct 21–23, 2026 at Institut Pasteur, Paris, for multidisciplinary cell biology, imaging, talks, posters & outreach, w/ Manuel Théry's behind-the-scenes look at the Musée d’Orsay video-mapping project. www.atoutcom.com/cell-la-vie/
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Wallace Marshall @wallaceucsf.bsky.social · 05/05/2026
If you are interested in how single cells are able to learn, check out this beautiful article by @niko-kukushkin.bsky.social www.sciencedirect.com/science/arti...
sciencedirect.com
Cellular memory: Learning without building
A new study reveals that habituation in the single-celled ciliate Stentor coeruleus uses the same calcium and kinase signaling as animal memory but do…
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