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PubMed2025

4D Microscopy and Tracking of Chromosomes and the Spindle in C. elegans Early Embryos.

Maintaining genomic integrity throughout successive cell divisions is essential for the proper development and functioning of organisms. Chromosome alignment and segregation occur on a microtubule-based spindle originating from centrosomes. The molecular and cellular mechanisms involved in accurate chromosome segregation during early embryonic divisions are highly conserved between worms and humans. Therefore, C. elegans serves as a robust model for investigating mitotic cell divisions within a metazoan system. Throughout early embryonic development, filming and tracking successive cell divisions becomes progressively more challenging as the number of cells increases and cell size decreases. To address this challenge, we describe a method for preparing live samples, performing 4D time-lapse imaging, and semi-automated tracking of chromosomes and spindle poles during early mitotic divisions in C. elegans embryos.

Caenorhabditis elegans↗
PubMed2026

Pcgf5 controls the exit from totipotency in mouse embryonic stem cells.

Mouse embryonic stem cell (ESC) cultures contain a rare subpopulation of two-cell-like cells (2CLCs) that transiently reactivate a two-cell embryo-like transcriptional program characteristic of zygotic genome activation (ZGA), including the endogenous retrovirus MERVL and Zscan4, and thereby regain a totipotent-like state. Polycomb repressive complex 1 (PRC1)-mediated H2AK119ub1 has been implicated in restraining entry into the 2C-like state through Pcgf6, yet the factors governing exit from this state and loss of totipotency remain poorly defined. Here, we show that among the six Pcgf paralogs, Pcgf5, which is most prominently upregulated in 2CLCs and forms an MERVL-driven chimeric transcript (Pcgf5MT2C_Mm) during ZGA in 2-cell embryos, controls exit from the 2C-like state in mouse ESCs. Using a reporter ESC line carrying MERVL-tdTomato and Zscan4c-EGFP (MtZG), we manipulated Pcgf5 dosage bidirectionally. Doxycycline (Dox)-inducible overexpression (OE) of Pcgf5 reduced the double-positive (DP) 2C-like population. Conversely, CRISPR-mediated knockout (KO) of Pcgf5 by targeting a common exon shared by all Pcgf5 variants (hereafter, total Pcgf5) increased the DP population. Time-lapse imaging directly confirmed that these changes reflected genuine differences in duration of the 2C-like state: OE shortened, whereas KO prolonged, the time cells spent in this state. These findings reveal that a Polycomb group factor controls not only entry into but also exit from the 2C-like state.

Animals↗
PubMed2026

Clinical applications of digital twin technology in In Vitro Fertilisation.

BACKGROUND: Digital twin technology, originating from aerospace and manufacturing industries, has emerged as a transformative tool in healthcare. In vitro fertilisation (IVF) faces persistent challenges including suboptimal embryo selection, unpredictable treatment outcomes, and limited personalisation of protocols. Despite advances in assisted reproductive technology, existing literature exhibits fragmentation: artificial intelligence applications in embryo selection, ovarian stimulation, and endometrial assessment have been developed independently without systematic integration into comprehensive treatment frameworks. Digital twin technology offers unprecedented opportunities to create virtual replicas of biological systems, enabling real-time monitoring, predictive modelling, and personalised treatment strategies. AIM: This narrative review aims to critically examine the current applications of digital twin technology in IVF, evaluate its potential benefits and limitations, synthesize existing evidence into an integrative conceptual model, and identify future directions for implementation in reproductive medicine. METHOD: A comprehensive narrative review was conducted using PubMed, Scopus, Web of Science, and IEEE Xplore databases. A narrative review approach was selected over systematic review to accommodate the heterogeneity of evidence types in this emerging field, including theoretical frameworks, simulation studies, and proof-of-concept implementations that would be excluded from systematic reviews. Search terms included "digital twin," "IVF," "in vitro fertilisation," "assisted reproductive technology," "embryo selection," and "predictive modelling." Studies published between 2015 and 2025 were included, focusing on original research articles, systematic reviews, and proof-of-concept studies describing digital twin applications in reproductive medicine. RESULTS: Digital twin technology in IVF demonstrates significant potential across multiple domains including embryo development simulation, ovarian response prediction, endometrial receptivity modelling, and personalised stimulation protocols. Current applications integrate artificial intelligence, machine learning algorithms, time-lapse imaging, and omics data to create comprehensive virtual models. Early evidence suggests improvements in embryo selection accuracy, ovarian response prediction, and treatment protocol optimization, though large-scale randomized controlled trials remain limited. Implementation challenges include data integration complexity, computational requirements, regulatory considerations, and validation requirements. CONCLUSION: Digital twin technology represents a paradigm shift in IVF practice, offering personalised, predictive, and precision medicine approaches. This review synthesizes existing evidence to propose an integrative conceptual model for digital twin implementation across the IVF treatment spectrum, identifies critical knowledge gaps, and establishes research priorities to advance clinical translation. Despite current limitations, continued advancement promises improved success rates and patient outcomes.

Humans↗
PubMed2026

Trimeric autotransporter adhesins driving chain-like adhesion diversify surface colonization strategies in Shiga toxin-producing Escherichia coli.

Bacteria frequently colonize host and environmental surfaces under fluid flow. Chain-like adherence pattern (CLAP) is an EibG-mediated surface colonization phenotype of certain Shiga toxin-producing Escherichia coli (STEC) that lack the locus of enterocyte effacement (LEE). EibG, an immunoglobulin-binding trimeric autotransporter adhesin, drives CLAP, but the temporal dynamics and genetic diversity underlying chain formation remain unclear. Here, we use live-cell time-lapse imaging to show that chains arise from single cells that elongate and divide without separation. Under flow, chains resist detachment and undergo shear-dependent fragmentation at cell-cell junctions, releasing viable clonal units that disperse downstream. Comparative genomics reveals diversity among EibG-related adhesins and identifies distinct lineages, including chain-like adhesins (Cla) that mediate CLAP while lacking IgG binding. Screening of 1,354 genomes from England shows that claB is present in 95.6% of strains from major LEE-negative STEC serotypes, highlighting its epidemiological prevalence. Targeted mutagenesis demonstrates that chain formation and IgG binding are mediated by distinct structural domains, revealing the modular functional architecture of these adhesins. Furthermore, we show that EibG, ClaA, and ClaB confer robust resistance to complement-mediated killing. Collectively, these findings establish CLAP as a dynamic, surface-associated strategy of LEE-negative STEC and reveal diversification among adhesins that drive this behavior.

Bacterial Adhesion↗
PubMed2009

Nap1-mediated actin remodeling is essential for mammalian myoblast fusion.

Myoblast fusion is crucial for the formation, growth, maintenance and regeneration of healthy skeletal muscle. Unfortunately, the molecular machinery, cell behaviors, and membrane and cytoskeletal remodeling events that govern fusion and myofiber formation remain poorly understood. Using time-lapse imaging approaches on mouse C2C12 myoblasts, we identify discrete and specific molecular events at myoblast membranes during fusion and myotube formation. These events include rearrangement of cell shape from fibroblast to spindle-like morphologies, changes in lamellipodial and filopodial extensions during different periods of differentiation, and changes in membrane alignment and organization during fusion. We find that actin-cytoskeleton remodeling is crucial for these events: pharmacological inhibition of F-actin polymerization leads to decreased lamellipodial and filopodial extensions and to reduced myoblast fusion. Additionally, shRNA-mediated inhibition of Nap1, a member of the WAVE actin-remodeling complex, results in accumulations of F-actin structures at the plasma membrane that are concomitant with a decrease in myoblast fusion. Our data highlight distinct and essential roles for actin cytoskeleton remodeling during mammalian myoblast fusion, provide a platform for cellular and molecular dissection of the fusion process, and suggest a functional conservation of Nap1-regulated actin-cytoskeleton remodeling during myoblast fusion between mammals and Drosophila.

Actins↗
PubMed2026

Cumulus cells enhance oocyte genomic quality control by promoting DNA damage-induced meiotic arrest.

Cumulus cells are known to maintain oocyte arrest at prophase I through gap junction-mediated cAMP signalling, but their role after meiotic resumption remains unclear. Here, we show that cumulus cells enhance oocyte genomic quality control by sensitizing mouse oocytes to DNA damage-induced meiotic arrest. Time-lapse imaging of SiR-tubulin-labelled spindles revealed that oocytes from cumulus-oocyte complexes (COCs) matured faster than denuded oocytes (DOs). Upon mild DNA damage induced by low-dose etoposide, COC oocytes arrested at metaphase I, whereas DOs completed maturation despite similar levels of DNA lesions. This arrest required spindle assembly checkpoint (SAC) activity, as reversine rescued polar body extrusion and BubR1 and Mad2 were elevated in COCs but not DOs. Disruption of gap junctions or inhibition of mTOR signalling abolished the checkpoint response. Notably, cumulus cells did not enhance oocyte response to minor spindle perturbations. These findings reveal a previously unrecognized role of cumulus cells in mediating DNA damage-induced SAC activation, providing post-GVBD genomic surveillance beyond prophase I arrest.

Animals↗
PubMed2023

Dominant negative variants in KIF5B cause osteogenesis imperfecta via down regulation of mTOR signaling.

BACKGROUND: Kinesin motor proteins transport intracellular cargo, including mRNA, proteins, and organelles. Pathogenic variants in kinesin-related genes have been implicated in neurodevelopmental disorders and skeletal dysplasias. We identified de novo, heterozygous variants in KIF5B, encoding a kinesin-1 subunit, in four individuals with osteogenesis imperfecta. The variants cluster within the highly conserved kinesin motor domain and are predicted to interfere with nucleotide binding, although the mechanistic consequences on cell signaling and function are unknown. METHODS: To understand the in vivo genetic mechanism of KIF5B variants, we modeled the p.Thr87Ile variant that was found in two patients in the C. elegans ortholog, unc-116, at the corresponding position (Thr90Ile) by CRISPR/Cas9 editing and performed functional analysis. Next, we studied the cellular and molecular consequences of the recurrent p.Thr87Ile variant by microscopy, RNA and protein analysis in NIH3T3 cells, primary human fibroblasts and bone biopsy. RESULTS: C. elegans heterozygous for the unc-116 Thr90Ile variant displayed abnormal body length and motility phenotypes that were suppressed by additional copies of the wild type allele, consistent with a dominant negative mechanism. Time-lapse imaging of GFP-tagged mitochondria showed defective mitochondria transport in unc-116 Thr90Ile neurons providing strong evidence for disrupted kinesin motor function. Microscopy studies in human cells showed dilated endoplasmic reticulum, multiple intracellular vacuoles, and abnormal distribution of the Golgi complex, supporting an intracellular trafficking defect. RNA sequencing, proteomic analysis, and bone immunohistochemistry demonstrated down regulation of the mTOR signaling pathway that was partially rescued with leucine supplementation in patient cells. CONCLUSION: We report dominant negative variants in the KIF5B kinesin motor domain in individuals with osteogenesis imperfecta. This study expands the spectrum of kinesin-related disorders and identifies dysregulated signaling targets for KIF5B in skeletal development.

Animals↗
PubMed2025

Unique growth and morphology properties of Clade 5 Clostridioides difficile strains revealed by single-cell time-lapse microscopy.

Clostridioides difficile is a gastrointestinal pathogen of both humans and agricultural animals and thus a major One Health threat. The C. difficile species consists of five main clades, with Clade 5 currently undergoing speciation from Clades 1-4. Since Clade 5 strains are highly prevalent in agricultural animals and a frequent cause of zoonotic infections, these strains may have evolved phenotypes that distinguish them from Clade 1-4 strains. Here, we compare the growth properties of Clade 5 strains to those of Clade 1-4 strains using anaerobic time-lapse microscopy coupled with automated image analysis. Our analyses indicate that Clade 5 strains grow faster and are more likely to form long chains of cells than Clade 1-4 strains. Using comparative genomic and CRISPRi analyses, we show that the chaining phenotype of Clade 5 strains is driven by the orientation of the invertible cmr switch sequence, with chaining strains exhibiting a bias to the cmr-ON state. Interestingly, Clade 5 strains with a bias towards the cmr-ON state shifted to a largely cmr-OFF state during murine infection, suggesting that the cmr-OFF state is under positive selection during infection. Collectively, our data reveal that Clade 5 strains have distinct growth properties, which may allow them to inhabit diverse ecological niches.

Clostridioides difficile↗
PubMed2025

Unique growth and morphology properties of Clade 5 Clostridioides difficile strains revealed by single-cell time-lapse microscopy.

Clostridioides difficile is a gastrointestinal pathogen of both humans and agricultural animals and thus a major One Health threat. The C. difficile species consists of five main clades, with Clade 5 currently undergoing speciation from Clades 1-4. Clade 5 strains are highly prevalent in agricultural animals and can cause zoonotic infections, suggesting that these strains have evolved phenotypes that distinguish them from Clade 1-4 strains. Here, we compare the growth properties of Clade 5 strains to those of Clade 1-4 strains using anaerobic time-lapse microscopy coupled with automated image analysis. Our analyses indicate that Clade 5 strains grow faster and are more likely to form long chains of cells than Clade 1-4 strains. Using comparative genomic and CRISPRi analyses, we show that the chaining phenotype of Clade 5 strains is driven by the orientation of the invertible cmr switch sequence, with chaining strains exhibiting a bias to the cmr-ON state. Interestingly, Clade 5 strains with a bias towards the cmr-ON state shifted to a largely cmr-OFF state during murine infection, suggesting that the cmr-OFF state is under positive selection during infection. Collectively, our data reveal that Clade 5 strains have distinct growth properties, which may allow them to inhabit diverse ecological niches.

Journal Article↗