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#CellDivision

0 Beiträge0 Beteiligte0 Beiträge heute
Rxiv mechanobio

📰 "Inherited or produced? Inferring protein production kinetics when protein counts are shaped by a cell's division history"
arxiv.org/abs/2506.09374 #Physics.Data-An #CellDivision #Q-Bio.Qm #Stat.Ml #Stat.Ap #Cell

arXiv logo
arXiv.orgInherited or produced? Inferring protein production kinetics when protein counts are shaped by a cell's division historyInferring protein production kinetics for dividing cells is complicated protein inheritance from the mother cell. For instance, fluorescence measurements -- commonly used to assess gene activation -- may reflect not only newly produced proteins but also those inherited through successive cell divisions. In such cases, observed protein levels in any given cell are shaped by its division history. As a case study, we examine activation of the glc3 gene in yeast involved in glycogen synthesis and expressed under nutrient-limiting conditions. We monitor this activity using snapshot fluorescence measurements via flow cytometry, where GFP expression reflects glc3 promoter activity. A naïve analysis of flow cytometry data ignoring cell division suggests many cells are active with low expression. Explicitly accounting for the (non-Markovian) effects of cell division and protein inheritance makes it impossible to write down a tractable likelihood -- a key ingredient in physics-inspired inference, defining the probability of observing data given a model. The dependence on a cell's division history breaks the assumptions of standard (Markovian) master equations, rendering traditional likelihood-based approaches inapplicable. Instead, we adapt conditional normalizing flows (a class of neural network models designed to learn probability distributions) to approximate otherwise intractable likelihoods from simulated data. In doing so, we find that glc3 is mostly inactive under stress, showing that while cells occasionally activate the gene, expression is brief and transient.
Rxiv mechanobio

📰 "Robust assessment of asymmetric division in colon cancer cells"
arxiv.org/abs/2409.19469 #Physics.Bio-Ph #CellDivision #Q-Bio.Cb #Cell

arXiv logo
arXiv.orgRobust assessment of asymmetric division in colon cancer cellsAsymmetric partition of fate determinants during cell division is a hallmark of cell differentiation. Recent work suggested that such a mechanism is hijacked by cancer cells to increase both their phenotypic heterogeneity and plasticity and in turn their fitness. To quantify fluctuations in the partitioning of cellular elements, imaging-based approaches are used, whose accuracy is limited by the difficulty of detecting cell divisions. Our work addresses this gap proposing a general method based on high-throughput flow cytometry measurements coupled with a theoretical framework. We applied our method to a panel of both normal and cancerous human colon cells, showing that different kinds of colon adenocarcinoma cells display very distinct extents of fluctuations in their cytoplasm partition, explained by an asymmetric division of their size. To test the accuracy of our population-level protocol, we directly measure the inherited fractions of cellular elements from extensive time-lapses of live-cell laser scanning microscopy, finding excellent agreement across the cell types. Ultimately, our flow cytometry-based method promises to be accurate and easily applicable to a wide range of biological systems where the quantification of partition fluctuations would help accounting for the observed phenotypic heterogeneity and plasticity
Rxiv mechanobio

📰 "Inherited or produced? Inferring protein production kinetics when protein counts are shaped by a cell's division history"
arxiv.org/abs/2506.09374 #Physics.Data-An #CellDivision #Q-Bio.Qm #Stat.Ml #Stat.Ap #Cell

arXiv logo
arXiv.orgInherited or produced? Inferring protein production kinetics when protein counts are shaped by a cell's division historyInferring protein production kinetics for dividing cells is complicated protein inheritance from the mother cell. For instance, fluorescence measurements -- commonly used to assess gene activation -- may reflect not only newly produced proteins but also those inherited through successive cell divisions. In such cases, observed protein levels in any given cell are shaped by its division history. As a case study, we examine activation of the glc3 gene in yeast involved in glycogen synthesis and expressed under nutrient-limiting conditions. We monitor this activity using snapshot fluorescence measurements via flow cytometry, where GFP expression reflects glc3 promoter activity. A naïve analysis of flow cytometry data ignoring cell division suggests many cells are active with low expression. Explicitly accounting for the (non-Markovian) effects of cell division and protein inheritance makes it impossible to write down a tractable likelihood -- a key ingredient in physics-inspired inference, defining the probability of observing data given a model. The dependence on a cell's division history breaks the assumptions of standard (Markovian) master equations, rendering traditional likelihood-based approaches inapplicable. Instead, we adapt conditional normalizing flows (a class of neural network models designed to learn probability distributions) to approximate otherwise intractable likelihoods from simulated data. In doing so, we find that glc3 is mostly inactive under stress, showing that while cells occasionally activate the gene, expression is brief and transient.
EPFL

🔬 Scientists from our Laboratory of Virology and Genetics have discovered that recently evolved genes play a key role in how our cells divide, revealing that even the most fundamental processes of life continue to evolve.

Find out more: go.epfl.ch/b84d00

go.epfl.ch · New genes, old job: the cell cycle evolvesScientists at EPFL have discovered that recently evolved genes play a key role in how our cells divide, revealing that even the most fundamental processes of life continue to evolve.
#CellDivision#Cell
Rxiv mechanobio

📰 "Mechanical force locally damages, remodels and stabilizes the lattice of spindle microtubules"
doi.org/doi:10.1101/2025.06.05
pubmed.ncbi.nlm.nih.gov/405016
#CellDivision #Mechanical #Cell

bioRxiv · Mechanical force locally damages, remodels and stabilizes the lattice of spindle microtubulesTo segregate chromosomes at cell division, the spindle must maintain its structure under force. How it does so remains poorly understood. To address this question, we use microneedle manipulation to apply local force to spindle microtubule bundles, kinetochore-fibers (k-fibers), inside mammalian cells. We show that local load directly fractures k-fibers, and that newly created plus-ends often have arrested dynamics, resisting depolymerization. Force alone, without fracture, is sufficient for spindle microtubule stabilization, as revealed by laser ablating k-fibers under local needle force. Doublecortin, which binds a compacted microtubule lattice, is lost around the force application site, suggesting local force-induced structural remodeling. In turn, EB1, which recognizes GTP-tubulin, is locally enriched at stabilization sites, both before and after force-induced fracture. Together, our findings support a model where force-induced damage leads to local spindle microtubule lattice remodeling and stabilization, which we propose reinforces the spindle where it experiences critical loads. ### Competing Interest Statement The authors have declared no competing interest. National Institutes of Health, R35GM136420 National Science Foundation, 1548297 CZ Biohub, https://ror.org/00knt4f32
Rxiv mechanobio

📰 "Simulation-trained conditional normalizing flows for likelihood approximation: a case study in stress regulation kinetics in yeast"
arxiv.org/abs/2506.09374 #Physics.Data-An #CellDivision #Q-Bio.Qm #Stat.Ml #Stat.Ap #Cell

arXiv logo
arXiv.orgInherited or produced? Inferring protein production kinetics when protein counts are shaped by a cell's division historyInferring protein production kinetics for dividing cells is complicated protein inheritance from the mother cell. For instance, fluorescence measurements -- commonly used to assess gene activation -- may reflect not only newly produced proteins but also those inherited through successive cell divisions. In such cases, observed protein levels in any given cell are shaped by its division history. As a case study, we examine activation of the glc3 gene in yeast involved in glycogen synthesis and expressed under nutrient-limiting conditions. We monitor this activity using snapshot fluorescence measurements via flow cytometry, where GFP expression reflects glc3 promoter activity. A naïve analysis of flow cytometry data ignoring cell division suggests many cells are active with low expression. Explicitly accounting for the (non-Markovian) effects of cell division and protein inheritance makes it impossible to write down a tractable likelihood -- a key ingredient in physics-inspired inference, defining the probability of observing data given a model. The dependence on a cell's division history breaks the assumptions of standard (Markovian) master equations, rendering traditional likelihood-based approaches inapplicable. Instead, we adapt conditional normalizing flows (a class of neural network models designed to learn probability distributions) to approximate otherwise intractable likelihoods from simulated data. In doing so, we find that glc3 is mostly inactive under stress, showing that while cells occasionally activate the gene, expression is brief and transient.
Rxiv mechanobio

📰 "Mechanical force locally damages, remodels and stabilizes the lattice of spindle microtubules"
biorxiv.org/content/10.1101/20 #CellDivision #Mechanical #Cell

bioRxiv · Mechanical force locally damages, remodels and stabilizes the lattice of spindle microtubulesTo segregate chromosomes at cell division, the spindle must maintain its structure under force. How it does so remains poorly understood. To address this question, we use microneedle manipulation to apply local force to spindle microtubule bundles, kinetochore-fibers (k-fibers), inside mammalian cells. We show that local load directly fractures k-fibers, and that newly created plus-ends often have arrested dynamics, resisting depolymerization. Force alone, without fracture, is sufficient for spindle microtubule stabilization, as revealed by laser ablating k-fibers under local needle force. Doublecortin, which binds a compacted microtubule lattice, is lost around the force application site, suggesting local force-induced structural remodeling. In turn, EB1, which recognizes GTP-tubulin, is locally enriched at stabilization sites, both before and after force-induced fracture. Together, our findings support a model where force-induced damage leads to local spindle microtubule lattice remodeling and stabilization, which we propose reinforces the spindle where it experiences critical loads. ### Competing Interest Statement The authors have declared no competing interest. National Institutes of Health, R35GM136420 National Science Foundation, 1548297 CZ Biohub, https://ror.org/00knt4f32
Rxiv mechanobio

📰 "Identification of Genes Required for Spatial Control and Mechanical Resilience of Cytokinesis during Caenorhabditis elegans Embryogenesis"
biorxiv.org/content/10.1101/20 #CellDivision #Mechanical #Cell

bioRxiv · Identification of Genes Required for Spatial Control and Mechanical Resilience of Cytokinesis during Caenorhabditis elegans EmbryogenesisCytokinesis is the final step of cell division, in which the dividing cell is physically separated into two daughter cells by the contractile ring. The contractile ring is a highly resilient molecular machine that can function　properly under mechanical stress. Additionally, its function, position, and orientation are spatially modulated in developing animals to regulate morphogenesis. Although essential regulators of cytokinesis have been identified through previous genetic screens, the molecular mechanisms underlying these spatial controls and the mechanical resilience of cytokinesis remain elusive. To identify cytokinesis regulators involved in these processes, we performed a high-throughput RNAi screen using a gain-of-function mutant of actin that exhibits ectopic cortical contraction and abnormal spatial control of cytokinesis in Caenorhabditis elegans embryos. We obtained a total of 483 early embryonic genes that suppress embryonic lethality in an act-2 mutant background. Two parallel secondary screens of candidate genes were conducted. The first secondary screen in a wild-type background identified 71 candidate genes regulating spatial cytokinesis control-asymmetric ring closure, positioning, and rotation-during early embryogenesis. The second secondary screen in the act-2(or295) background identified four genes required for cytokinesis in this background, including microtubule regulators, evl-20/ARL2 , and lpin-1/Lipin1 . This study will serve as a useful resource for the development of future hypotheses and provide insights into the precise regulation of cytokinesis in tissues. ### Competing Interest Statement The authors have declared no competing interest.
Rxiv mechanobio

📰 "Six decades of the FitzHugh-Nagumo model: A guide through its spatio-temporal dynamics and influence across disciplines"
arxiv.org/abs/2404.11403 #Physics.Comp-Ph #Physics.Bio-Ph #CellDivision #Q-Bio.Ot #Dynamics #Nlin.Ps #Math.Mp #Math-Ph #Cell

arXiv.orgSix decades of the FitzHugh-Nagumo model: A guide through its spatio-temporal dynamics and influence across disciplinesThe FitzHugh-Nagumo equation, originally conceived in neuroscience during the 1960s, became a key model providing a simplified view of excitable neuron cell behavior. Its applicability, however, extends beyond neuroscience into fields like cardiac physiology, cell division, population dynamics, electronics, and other natural phenomena. In this review spanning six decades of research, we discuss the diverse spatio-temporal dynamical behaviors described by the FitzHugh-Nagumo equation. These include dynamics like bistability, oscillations, and excitability, but it also addresses more complex phenomena such as traveling waves and extended patterns in coupled systems. The review serves as a guide for modelers aiming to utilize the strengths of the FitzHugh-Nagumo model to capture generic dynamical behavior. It not only catalogs known dynamical states and bifurcations, but also extends previous studies by providing stability and bifurcation analyses for coupled spatial systems.
Rxiv mechanobio

📰 "A self-organised liquid reaction container for cellular memory"
arxiv.org/abs/2412.15394 #Physics.Bio-Ph #CellDivision #Cell

arXiv.orgA self-organised liquid reaction container for cellular memoryEpigenetic inheritance during cell division is essential for preserving cell identity by stabilizing the overall chromatin organisation.Heterochromatin,the condensed and transcriptionally silent fraction of chromatin,is marked by specific epigenetic modifications that are diluted during each cell division.Here we build a physical model,based on the formation of a biomolecular condensate,a liquid 'droplet',that promotes the restoration of epigenetic marks.Heterochromatin facilitates the droplet formation via polymer-assisted condensation(PAC).The resulting condensate serves as a reaction chamber to reconstruct the lost epigenetic marks.We incorporate the enzymatic reactions into a particle-based simulation and monitor the progress of the epigenetic markers through an in silico analogue of the cell cycle.We demonstrate that the proposed mechanism is robust and stabilizes the heterochromatin domains over many cell generations.This mechanism and variations thereof might be at work for other epigenetic marks as well.
Rxiv mechanobio

📰 "A self-organised liquid reaction container for cellular memory"
arxiv.org/abs/2412.15394 #Physics.Bio-Ph #CellDivision #Cell

arXiv.orgA self-organised liquid reaction container for cellular memoryEpigenetic inheritance during cell division is essential for preserving cell identity by stabilizing the overall chromatin organisation.Heterochromatin,the condensed and transcriptionally silent fraction of chromatin,is marked by specific epigenetic modifications that are diluted during each cell division.Here we build a physical model,based on the formation of a biomolecular condensate,a liquid 'droplet',that promotes the restoration of epigenetic marks.Heterochromatin facilitates the droplet formation via polymer-assisted condensation(PAC).The resulting condensate serves as a reaction chamber to reconstruct the lost epigenetic marks.We incorporate the enzymatic reactions into a particle-based simulation and monitor the progress of the epigenetic markers through an in silico analogue of the cell cycle.We demonstrate that the proposed mechanism is robust and stabilizes the heterochromatin domains over many cell generations.This mechanism and variations thereof might be at work for other epigenetic marks as well.
Lukas VFN 🇪🇺

Researchers explain how #mushrooms can live for hundreds of years without getting cancer phys.org/news/2023-07-mushroom

Longevity of Fungal #Mycelia and Nuclear Quality Checks: a New Hypothesis for the Role of Clamp Connections in Dikaryons journals.asm.org/doi/10.1128/m

"Some #fungi seem to deploy a special type of #CellDivision to prevent selfish #mutations from being selected, drastically reducing the risk of #cancer."

D. Allan Drummond

Continuing #introduction: by day I'm a professor (biochemistry & cell biology) running a research lab where we've published many studies using budding yeast (think beer and bread).

So naturally, as an artist by night, I had to sculpt our favorite organism. Here is Saccharomyces cerevisiae in late anaphase, mother cell producing a daughter cell, jeweled chromosomes separating inside the nucleus. Bronze, silver, 3D printed steel, and apatite gemstones. #sciart #cellbiology #celldivision

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