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Results for “developmental biology”

Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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bioRxiv2019

ΔSCOPE: A new method to quantify 3D biological structures and identify differences in zebrafish forebrain development

Research in the life sciences has traditionally relied on the analysis of clear morphological phenotypes, which are often revealed using increasingly powerful microscopy techniques analyzed as maximum intensity projections (MIPs). However, as biology turns towards the analysis of more subtle phenotypes, MIPs and qualitative approaches are failing to adequately describe these phenotypes. To address these limitations and quantitatively analyze the three-dimensional (3D) spatial relationships of biological structures, we developed the computational method and program called {Delta}SCOPE (Changes in Spatial Cylindrical Coordinate Orientation using PCA Examination). Our approach uses the fluorescent signal distribution within a 3D data set and reorients the fluorescent signal to a relative biological reference structure. This approach enables quantification and statistical analysis of spatial relationships and signal density in 3D multichannel signals that are positioned around a well-defined structure contained in a reference channel. We validated the application of {Delta}SCOPE by analyzing normal axon and glial cell guidance in the zebrafish forebrain and by quantifying the commissural phenotypes associated with abnormal Slit guidance cue expression in the forebrain. Despite commissural phenotypes which display disruptions to the reference structure, {Delta}SCOPE was able to detect subtle, previously uncharacterized changes in zebrafish forebrain midline crossing axons and glia. This method has been developed as a user-friendly, open source program. We propose that {Delta}SCOPE is an innovative approach to advancing the state of image quantification in the field of high resolution microscopy, and that the techniques presented here are of broad applications to the life science field.

developmental biology↗

bioRxiv2020

Epigenetic clock and methylation studies in the rhesus macaque

Methylation levels at specific CpG positions in the genome have been used to develop accurate estimators of chronological age in humans, mice, and other species. Although epigenetic clocks are generally species-specific, the principles underpinning them appear to be conserved at least across the mammalian class. This is exemplified by the successful development of epigenetic clocks for mice and several other mammalian species. Here, we describe epigenetic clocks for the rhesus macaque (Macaca mulatta), the most widely used nonhuman primate in biological research. Using a custom methylation array (HorvathMammalMethylChip40), we profiled n=281 tissue samples (blood, skin, adipose, kidney, liver, lung, muscle, and cerebral cortex). From these data, we generated five epigenetic clocks for macaques. These clocks differ with regards to applicability to different tissue types (pan-tissue, blood, skin), species (macaque only or both humans and macaques), and measure of age (chronological age versus relative age). Additionally, the age-based human-macaque clock exhibits a high age correlation (R=0.89) with the vervet monkey (Chlorocebus sabaeus), another Old World species. Four CpGs within the KLF14 promoter were consistently altered with age in four tissues (adipose, blood, cerebral cortex, skin). It is expected that the macaque clocks will reveal an epigenetic aging rate associated with a host of health conditions and thus lend themselves for identifying and validating anti-aging interventions.

developmental biology↗

bioRxiv2022

EZ Clear for simple, rapid, and robust mouse whole organ clearing

Tissue clearing for whole organ cell profiling has revolutionized biology and imaging for exploration of organs in three-dimensional space without compromising tissue architecture. But complicated, laborious procedures, or expensive equipment, as well as the use of hazardous, organic solvents prevents the widespread adoption of these methods. Here we report a simple and rapid tissue clearing method, EZ Clear, that can clear whole adult mouse organs in 48 hours in just three simple steps. Samples stay at room temperature and remain hydrated throughout the clearing process, preserving endogenous and synthetic fluorescence, without altering sample size. After wholemount clearing and imaging, EZ Cleared samples can be further processed for downstream embedding and cryosectioning followed by standard histology or immunostaining, without loss of endogenous or synthetic fluorescence signal. Overall, the simplicity, speed, and flexibility of EZ Clear make it easy to adopt and apply to diverse approaches in biomedical research.

developmental biology↗

bioRxiv2025

Zebrafish genetic model of neuromuscular degeneration associated with Atrogin-1 expression

The degenerative loss of muscle associated with aging leading to muscular atrophy is called sarcopenia. Currently, practicing regular physical exercise is the only efficient way to delay sarcopenia onset. Identification of therapeutic targets to alleviate the symptoms of aging requires in vivo model organisms of accelerated muscle degeneration and atrophy. The zebrafish undergoes aging, with hallmarks including mitochondrial dysfunction, telomere shortening, and accumulation of senescent cells. However, zebrafish age slowly, and no specific zebrafish models of accelerated muscle atrophy associated with molecular events of aging are currently available. We have developed a new genetic tool to efficiently accelerate muscle-fiber degeneration and muscle-tissue atrophy in zebrafish larvae and adults. We used a gain-of-function strategy with a molecule that has been shown to be necessary and sufficient to induce muscle atrophy and a sarcopenia phenotype in mammals: Atrogin-1 (also named Fbxo32). We report the generation, validation, and characterization of a zebrafish genetic model of accelerated neuromuscular atrophy, the atrofish. We demonstrated that Atrogin-1 expression specifically in skeletal muscle tissue induces a muscle atrophic phenotype associated with locomotion dysfunction in both larvae and adult fish. We identified degradation of the myosin light chain as an event occurring prior to muscle-fiber degeneration. Biological processes associated with muscle aging such as proteolysis, inflammation, stress response, extracellular matrix (ECM) remodeling, and apoptosis are upregulated in the atrofish. Surprisingly, we observed a strong correlation between muscle-fiber degeneration and reduced numbers of neuromuscular junctions in the peripheral nervous system, as well as neuronal cell bodies in the spinal cord, suggesting that muscle atrophy could underly a neurodegenerative phenotype in the central nervous system. Finally, while atrofish larvae can recover locomotive functions, adult atrofish have impaired regenerative capacities, as is observed in mammals during muscle aging. In the future, the atrofish could serve as a platform for testing molecules aimed at treating or alleviating the symptoms of muscle aging, thereby opening new therapeutic avenues in the fight against sarcopenia.

developmental biology↗

bioRxiv2025

Refate identifies chemical compounds to target trans-regulatory networks for cellular conversion

Identifying chemical compounds that target trans-regulatory networks (TRNs) underlying molecular programs of cells for directed cellular conversion (i.e. differentiation, reprogramming, transdifferentiation, and dedifferentiation) is a key step towards advancing regenerative medicine. Recent innovations in single-cell omics technologies enabled high-resolution profiling of TRNs that govern cell identity and cell-fate decisions. Here, we introduce Refate, a computational framework that integrates large-scale multimodal single-cell atlas data to quantify cell propensity of genes, together with six drug databases, to identify chemical compounds that target TRNs for directed cellular conversion. The reconstructed TRNs, including protein-protein interactions and gene regulatory networks, alongside chemical compounds that drive the cellular conversion provide greater biological interpretability and improve efficiency and efficacy. We evaluated Refate by testing its ability to uncover known transcription factors and chemical compounds validated in experimental conversions of various cell types. Furthermore, we experimentally validated the attribute of several novel chemical compounds identified by Refate for enhancing the conversion of human embryonic stem cells to human cranial neural crest cells. Together, these findings demonstrate Refate as an effective tool for discovering chemical compounds that target TRNs to enable cellular conversion, advancing efforts towards regenerative medicine. HighlightsO_LIRefate quantifies genes for cellular conversion using multimodal single-cell atlases C_LIO_LIRefate uncovers trans-regulatory networks (TRNs) underlying cellular conversion C_LIO_LIRefate identifies chemical compounds that target TRNs for cellular conversion C_LIO_LIValidation of Refate identified chemical compounds for hESC to hCNCC conversion C_LI

developmental biology↗

bioRxiv2019

The lncRNAs Implicated in Redox Regulation in Ybx1 Deficient Zebrafish Larvae

Ybx1 has been demonstrated as a crucial gene in embryogenesis, reproduction as well as development in various vertebrates such as mouse and zebrafish. However, the underlying lncRNA-mediated mechanisms require deep investigation. Particularly, the importance of lncRNA to vertebrate development is controversial and questionable since many studies have yielded contradictory conclusions for the same lncRNAs. In the present study, in order to disclose the lncRNAs implicated in vertebrate development, a systematic transcriptome analysis is conducted based on the RNA sequencing data derived from ybx1 homozygous mutant zebrafish on day5 (day5_ybx1-/-) as well as wild type zebrafish on day5 and day6 (day5_ybx1+/+, day6_ybx1+/+). A high-confidence dataset of zebrafish lncRNAs is detected using a stepwise filtering pipeline. Differential expression analysis and co-expression network analysis reveal that several lncRNAs probably act on duox and noxo1a, the genes related to redox (reduction-oxidation reaction) processes which are triggered by ybx1 disruption. Validation by an experimental study on three selected lncRNAs indicates that knockdown of all selected lncRNAs leads to morphological deformation of larvae. In addition, our experiments effectively support the prediction of network analysis in many interaction patterns between the selected lncRNAs and the two redox genes (duox, noxo1a). In short, our study provides new insights into the function and mechanism of lncRNAs implicated in zebrafish embryonic development and demonstrates the importance of lncRNAs in vertebrate development.\n\nAuthor SummaryLncRNAs has been emerged as key regulatory layers because of their multiple functions in diverse biological processes and pathways. However, there is disagreement about the roles of lncRNAs in vertebrate development Some cases demonstrated that lncRNAs was important to development. Others showed that lncRNAs just have feeble functions in development. On the other hand, Ybx1 processing multi-functions has been well demonstrated as a key protein to most vertebrate in development. Hence, aimed at disclosure of key lncRNAs implicated in vertebrate development as well as their possible roles, we performed a systematic transcriptome analysis based on the deep RNA sequencing data of ybx1 homozygous mutant zebrafish and wild type zebrafish. Our analysis successfully revealed several lncRNAs probably target on the redox-related genes. Furthermore, our experiments validated the importance of these lncRNAs to zebrafish embryo development. This study is the first to utilize Ybx1 as breakpoint to identify key lncRNA related to vertebrate development and provides new insights into underlying mechanisms of lncRNAs in development.

developmental biology↗

bioRxiv2019

A portable, low-cost device for precise control of specimen temperature under stereomicroscopes

To facilitate precise and convenient control of biological sample temperature, we developed a low-cost device that can be used independently or with any stereomicroscope. The purpose of the device is to control the thermal environment during experimental intervals in which a specimen must be manipulated outside of an incubator, e.g. for dissection or slide-mounting in preparation for imaging. Sample temperatures can be both cooled to below and heated to above room temperatures, and stably maintained at a precision of +/- 0.1{degrees}C. To demonstrate the utility of this device, we report improved characterization of the penetrance of a short-acting temperature-sensitive allele in C. elegans embryos, and identification of the upper temperature threshold for embryonic viability for six Caenorhabditis species. By controlling the temperature environment even as a specimen is manipulated, this device offers consistency and flexibility, reduces environmental noise, and enables precision timing in experiments requiring temperature shifts.

developmental biology↗

bioRxiv2021

microRNA Expression Levels Change in Neonatal Patients During and After Exposure to Cardiopulmonary Bypass

ObjectivesThe systemic inflammation that occurs after exposure to cardiopulmonary bypass (CPB), which is especially severe in neonatal patients, is associated with poorer outcomes and is not well understood. In order to gain deeper insight into how exposure to bypass activates inflammatory responses in circulating leukocytes, we studied changes in microRNA (miRNA) expression during and after exposure to bypass. miRNAs are small non-coding RNAs that have important roles in modulating protein levels and function of cells. MethodsWe performed miRNA-Sequencing on leukocytes isolated from neonatal cardiopulmonary bypass patients (N=5) at 7 timepoints during the process of CPB, including prior to the initiation of bypass, during bypass, and at three time points during the first 24 hours after weaning from bypass. We identified significant differentially expressed miRNAs using generalized linear regression models, and miRNAs were defined as statistically significant using an FDR adjusted p <0.05. We identified gene targets of these miRNAs using the Targetscan database, and identified significantly enriched biological pathways for these gene targets. ResultsWe identified 54 miRNAs with differential expression during and after CPB. These miRNAs clustered into 3 groups, including miRNAs that were increased during and after CPB (3 miRNAs), miRNAs that decreased during and after CPB (10 miRNAs), and miRNAs that decreased during CPB but then increased 8-24 hours after CPB. 38.9% of the target genes of these miRNAs were significantly differentially expressed in our previous study. miRNAs with altered expression levels are predicted to significantly modulate pathways related to inflammation and signal transduction. ConclusionsThe unbiased profiling of the miRNA changes that occur in the circulating leukocytes of bypass patients provides deeper insight into the mechanisms that underpin the systemic inflammatory response that occurs in patients after exposure to cardiopulmonary bypass. These data will help the development of novel treatments and biomarkers for bypass associated inflammation.

developmental biology↗

bioRxiv2024

Assessment of the hypoglycemic activity of trans-cinnamic acid isolated from the extract of hairy rots Scutellaria baicalensis in in vivo experiments

AnnotationHypoglycemia is the process of reducing blood glucose concentration to below 2.5-2.8 mmol/L in men and less than 1.9-2.2 mmol/L in women. Prolonged hyperglycemia can lead to a range of serious chronic complications such as diabetic nephropathy, diabetic retinopathy, cardiovascular diseases in diabetes, and so forth, threatening human life, health, and safety. Scutellaria baicalensis is one of the most commonly used remedies in traditional Chinese medicine. This plant contains a number of biologically active compounds that contribute to improving kidney function, insulin resistance, and retinopathy in patients with type 2 diabetes, but few researchers study the toxic effects of medicinal plant components. Therefore, the aim of this study was to evaluate the hypoglycemic activity of trans-cinnamic acid isolated from the extract of hairy rots of Scutellaria baicalensis in in vivo experiments. This study involved intraperitoneal administration of alloxan at a dose of 150.0 mg/kg and oral administration of trans-cinnamic acid at doses of 50.0 and 100.0 mg/kg. During the experiment, it was found that trans-cinnamic acid at the presented doses does not affect the body weight dynamics of experimental animals with diabetes. Thus, this study demonstrates that trans-cinnamic acid at the presented dosage can be safely used as an ingredient in the creation of dietary supplements for the prevention of diabetes, thereby contributing to healthy aging.

developmental biology↗

bioRxiv2024

Local control of cellular proliferation underlies neuromast regeneration in zebrafish

Biological systems are never in equilibrium but maintain stability despite continuous external disturbances. A prime example of this is organ regeneration, where, despite intrinsically stochastic damage, organs are rebuilt through controlled cellular proliferation. In this study, we employ a cell- based computational modelling approach to investigate the proliferative response to injury. We developed a minimal two-dimensional Cellular Potts Model (CPM) using empirical data from regenerating neuromasts in larval zebrafish. Remarkably, the CPM both qualitatively and quantitatively recapitulates the regenerative response of neuromasts following laser-mediated cell ablation. Assuming that cell proliferation is locally regulated by a delayed switch, mitotic activity ceases once the type-dependent number of neighbouring cells exceeds a deterministic critical threshold. An intriguing corollary of our findings is that a local negative feedback loop among identical cells may represent a general mechanism underlying organ-level proportional homeostasis.

developmental biology↗

bioRxiv2025

The Binary Cellular Biology of Human Growth II Calculating the Size of the Human Fetus from the Size of its Parts

Assessing and understanding the Size of the human fetus provides essential information for the management of the health of the newborn and its mother, a quality that is commonly measured by Fetal Ultrasound. Many equations for making such calculations have been considered, none of which have been entirely satisfactory. As we have shown in the previous paper in this series, a consideration of the formation of the body, in units of numbers of cells, N, an approach we call Binary Cellular Analysis, provides new quantitative tools for estimating the Size and Age of the fetus. These tools include a new mathematical basis for creating useful expressions, Binary Cellular Estimated Fetal Weight Equations, for calculating human Fetal Weight from Ultrasound Measurements. As we show here, the most promising of these expressions, the Abdominal Circumference Binary Cellular Estimated Fetal Weight Equation, performs better than other currently used Fetal Weight Equations, while also yielding up new methods for improving ultrasound size assessment. Web-based calculators (https://kidzgrowth.com) make these mathematical manipulations available for obstetric care.

developmental biology↗

bioRxiv2025

Contributions of m6A RNA methylation to germline development in the planarian Schmidtea mediterranea

N6-methyladenosine (m6A) is one of the most prevalent post-transcriptional modifications of eukaryotic RNA molecules. This post-transcriptional modification is essential in biological contexts ranging from metabolism to cellular differentiation and neuronal function. While the role of m6A RNA regulation in the soma of planarian flatworms has been previously studied, the presence and biological relevance of this regulatory pathway in the germline of these or other lophotrochozoans remains unknown. Here, we characterize m6A RNA regulation factors in the planarian Schmidtea mediterranea and analyze their function in development of the germline. Enriched expression of orthologs of m6A methyltransferase complex components, namely Smed-METTL3, Smed-METTL14, and WTAP, was detected in ovaries and testes of S. mediterranea. Perturbation of these factors by RNA-interference (RNAi) disrupted intermediate steps in oogenesis and spermatogenesis, but the presence of germline stem cells was not affected. Expression of m6A "reader" homologs was also detected in the planarian gonads. Sperm development defects were observed upon Smed-YTHDF2-3 RNAi, and combined knockdown of Smed-YTHDF2-3, Smed-YTHDF2-2, or Smed-YTHDF1-2 with that of writers led to increased frequency of germline development defects. These results indicate that regulation of RNA bym6A methylation supports male and female germline development in planarian flatworms.

developmental biology↗

bioRxiv2018

Functional heterogeneity within the developing zebrafish epicardium

The epicardium is essential during cardiac development, homeostasis and repair and yet fundamental insights into its underlying cell biology, notably epicardium formation, lineage heterogeneity and functional cross-talk with other cell types in the heart, are currently lacking. In this study, we investigated epicardial heterogeneity and the functional diversity of discrete epicardial subpopulations in the developing zebrafish heart. Single-cell RNA-sequencing uncovered three epicardial subpopulations with specific genetic programmes and distinctive spatial distribution within the developing heart. Perturbation of unique gene signatures uncovered distinct functions associated with each subpopulation and established novel epicardial roles in cell adhesion, migration, and chemotaxis as a mechanism for recruitment of leukocytes into the heart. This work elucidates the mutual spatiotemporal relationships between different epicardial subpopulations and assigns unique function to each during cardiac development. Understanding which mechanisms cells employ to establish a functional epicardium and to communicate with other cardiovascular cell types during development will bring us closer to repairing cellular relationships that are disrupted during cardiovascular disease.

developmental biology↗

bioRxiv2019

Spatiotemporal control of gene expression boundaries using a feedforward loop

A feed forward loop (FFL) is commonly observed in several biological networks. The FFL network motif has been mostly been studied with respect to variation of the input signal in time, with only a few studies of FFL activity in a spatially distributed system such as morphogen-mediated tissue patterning. However, most morphogen gradients also evolve in time. We studied the spatiotemporal behavior of a coherent FFL in two contexts: (1) a generic, oscillating morphogen gradient and (2) the dorsal-ventral patterning of the early Drosophila embryo by a gradient of the NF-{kappa}B homolog Dorsal with its early target Twist. In both models, we found features in the dynamics of the intermediate node - phase difference and noise filtering - that were largely independent of the parameterization of the models, and thus were functions of the structure of the FFL itself. In the Dorsal gradient model, we also found that the dynamics of Dorsal require maternal pioneering factor Zelda for proper target gene expression.

developmental biology↗

bioRxiv2016

Anchor negatively regulates BMP signaling to control Drosophila wing development

Summary statementThe novel gene anchor is the ortholog of vertebrate GPR155, which contributes to preventing wing disc tissue overgrowth and limiting the phosphorylation of Mad in presumptive veins during the pupal stage.\n\nG protein-coupled receptors play a particularly important function in many organisms. The novel Drosophila gene anchor is the ortholog of vertebrate GPR155, and its molecular function and biological process are not yet known, especially in wing development. Knocking down anchor resulted in increased wing size and extra and thickened veins. These abnormal wing phenotypes are similar to those observed in gain-of-function of BMP signaling experiments. We observed that the BMP signaling indicator p-Mad was significantly increased in anchor RNAi-induced wing discs in larvae and that it also abnormally accumulated in intervein regions in pupae. Furthermore, the expression of BMP signaling pathway target genes were examined using a lacZ reporter, and the results indicated that omb and sal were substantially increased in anchor knockdown wing discs. In a study of genetic interactions between Anchor and BMP signaling pathway, the broadened and ectopic vein tissues were rescued by knocking down BMP levels. The results suggested that the function of Anchor is to negatively regulate BMP signaling during wing development and vein formation, and that Anchor targets or works upstream of Dpp.

Developmental Biology↗

bioRxiv2023

Temporal Notch signaling regulates mucociliary cell fates through Hes-mediated competitive de-repression

Mucociliary epithelia are found across different organs in animals, where they release bioactive substances and generate extracellular fluid flows. One key function of mucociliary epithelia is the clearance of pathogens, e.g. in the vertebrate lung and the epidermis of amphibian tadpoles. Mucociliary clearance relies on the correct balance between secretory cells that release mucus, ciliated cells that generate fluid flow as well as specialized cell types, including pH-regulating ionocytes and basal stem cells. Notch signaling, Hes repressors and cell type-inducing transcription factors (e.g. Foxi1, Mcidas, Spdef and Tp63) regulate cell fates and cell type proportions across mucociliary systems. Lateral inhibition was proposed to control mucociliary cell fates, but current models cannot explain how more than two cell types are generated and how Hes genes are employed as mediators during patterning. Using the Xenopus tadpole epidermis, we addressed these open questions in mucociliary biology through a combination of in vivo and organoid experiments, time-resolved transcriptomic studies and mathematical modeling. This revealed that ionocytes, ciliated cells, secretory cells and basal cells are preferentially specified at different time points and Notch signaling levels via sequentially expressed Hes factors. We termed this mode of patterning "competitive de-repression", because cell fates are selected by suppression of alternative fate choices, and demonstrate that this relies on differential active repression of cell fate transcription factors. Mathematical modeling further indicated the need for a positively Notch-regulated patterning factor, and we provide evidence that Spdef mediates Notch input for secretory and basal cell specification. Collectively, this work presents a coherent model for Notch- and Hes-mediated mucociliary cell fate specification in a vertebrate tissue, which allows for the specification of more than two cell fates within the Notch lateral-inhibition paradigm.

developmental biology↗

bioRxiv2023

Emergent order in epithelial sheets by interplay of cell divisions and cell fate regulation

The fate choices of stem cells between self-renewal and differentiation are often tightly regulated by paracrine (cell-cell) signalling. Here, we assess how the interplay between cell division, differentiation, and short range paracrine signalling can affect the macroscopic ordering of cell types in self-renewing epithelial sheets, by studying a simple spatial cell fate model with cells being arranged on a 2D lattice. We show in this model that if cells commit to their fate directly upon cell division, macroscopic domains of cells of the same type emerge, if at least a small proportion of divisions are symmetric, except if signalling interactions are laterally inhibiting. In contrast, if cells are first licensed to differentiate, yet retaining the possibility to return to their naive state, macroscopic order only emerges if the signalling strength exceeds a critical threshold: if then the signalling interactions are laterally inducing, macroscopic domains emerge as well. Lateral inhibition, on the other hand, can in that case generate macroscopic patterns of alternating cell types (checkerboard pattern), yet only if the proportion of symmetric divisions is sufficiently low. These results can be understood theoretically by an analogy to phase transitions in spin systems known from statistical physics. Author summaryA fundamental question in stem cell biology is how a cells choice to differentiate or not (cell fate choices), is regulated through communication with other cells in a tissue, and whether these choices are a one-way path or to some degree reversible. However, measuring this in living animals is very difficult and often impossible, since this requires to make videos of cells inside the body with a microscope. Here, we employ a simple mathematical model for the fate choices of stem cells when they are regulated by communication with nearby cells in the tissue. We show that different means of cell fate choice and cell communication can lead to qualitatively different patterns of cell types: macroscopic domains, checkerboard patterns, or randomly disordered distributions, depending on the character of cell communication, and whether cell fate is one-way or reversible. Our analysis therefore shows that those aspects of stem cell activity, which are otherwise difficult to measure, can be distinguished by observing macroscopic patterns of cell types.

developmental biology↗

bioRxiv2021

Mechanical Causation of Biological Structure: Productive Pulls Produce Persistent Filaments in a Human Fibroblast Model of Matrix Development

The principal mechanisms driving the synthesis and organization of durable animal structure have been the subject of intense investigation for decades. Here, we present evidence that mechanical strains can direct the formation of extracellular matrix (ECM) filaments via a mechanochemical cascade. This process is driven by cooperative cell contractions ("pulls") that organize and precipitate structure via strain-induced polymer assembly. In an in vitro model of ECM synthesis, we use high-resolution optical microscopy to observe the kinematics of cell motion during their growth to confluency and identified cell-to-cell pulls that result in the production of persistent ECM filaments. Using live-cell confocal imaging, we confirmed that these pulls can directly cause the formation of fibronectin filaments that then bind collagen, producing persistent structures aligned with the direction of the pull. The finding suggests a new model for initial durable structure formation in animals based on local cell contraction, extensional strain and polymer mechanochemistry. The results have important implications for ECM development, growth and life-threatening pathologies of the ECM such as fibrosis.

developmental biology↗