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Biology subjects

Sethi, S.

Publications and source records attributed to Sethi, S..

At least 19 recordsLinked to original sources

Automated bird flight pattern extraction and classification using machine learning

With bird populations across the world being impacted by ever-growing anthropogenic pressures, reliable monitoring is essential to help halt or reverse declines. Existing visual bird monitoring approaches, which employ cameras or radars to deliver automated and large-scale monitoring data, face a variety of issues. Image-based species classification is only possible if the fine-scale features of a bird are clear, which can be difficult to achieve in real monitoring contexts without expensive, high-resolution cameras due to occlusion and lighting. Radar and video-based approaches which analyse longer-term flight behaviour over the course of seconds can achieve more reliable results in real monitoring contexts, particularly from greater distances, but still require expensive equipment and do not account for all the possible types of flight patterns. Here we present a novel approach to track a wide range of bird flight patterns using inexpensive equipment. As a proof-of-concept, we demonstrate how our approach can be used to classify birds between four species, Red Kite, Kestrel, Black-Headed Gull and Sparrowhawk, which represent four different types of flight patterns. The balanced accuracy of the classification is 0.5583, with a recall and precision per species that range from 0.2640-0.7750 and 0.4583-0.5962, respectively. Our proof-of-concept study demonstrates how new and existing visual bird monitoring systems can leverage flight patterns to deliver species-level insights at lower costs and on larger scales than before.

ecology↗

ADAPTATION AGAINST LONG-TERM PROTEIN DEPRIVATION TRADES OFF WITH IMMUNOCOMPETENCE AND THE ABILITY TO SURVIVE PATHOGENIC INFECTIONS

Insufficient protein intake, leading to malnutrition, is a major global health concern that compromises the immune system and increases susceptibility to diseases. In scenarios where protein availability is constrained, organisms may experience strong selection to efficiently allocate their resources between immunity vs other energy-demanding processes, such as reproduction, resulting in evolutionary trade-offs. Additionally, in many species, protein deficiency has a more significant impact on female reproduction than on males, potentially leading to pronounced sexually dimorphic trade-offs involving immunity and infection outcomes. However, there are no experiments to test these possibilities. In this work, we demonstrate that in Drosophila melanogaster populations selected for increased early-life reproduction under protein limitations, evolved virgin females indeed suffered a greater reduction in their resistance to the pathogen Providencia rettgeri and showed lower survival following infection than males, corroborating our expectations. However, mating resulted in a loss of sexually dimorphic infection outcomes, causing both sexes to exhibit nearly identical infection costs and reduced infection tolerance compared to their ancestral, unselected populations. Moreover, several immune components, including the Toll- and IMD-mediated inducible immune pathways, were either less upregulated or more downregulated in the selected flies, which may contribute to their heightened susceptibility to pathogens. Downregulation in key metabolic pathways and genes related to phagocytosis, melanisation and ROS-mediated defence after infection in selected flies can also be associated with their increased pathogen vulnerability. Taken together, our work thus reveals the reproductive status- and sex-specific plasticity of immune investments and post-infection health in response to evolutionary constraints under chronic protein deprivation.

evolutionary biology↗

Stable Synthetic Organelles from Aqueous Two-Phase Systemswith Access to the Cell Translation Machinery

Cells compartmentalize vital processes in membrane-less organelles to gain spatiotemporal control of metabolism, signaling, and for protection under stress. While such compartments can be manipulated or even de novo designed with genetic engineering of cells, the transfer and operation of exogenous synthetic compartments for intracellular engineering is challenged by developing pathways for implantation into the cell, stability issues, toxicity, ability to maintain compartmentalization, and access to cellular machinery. Here we introduce dextran-lipid droplets as versatile exogenous synthetic compartments, that are readily uptaken by model cancer and immune cells and are stable inside cells for days. Furthermore, the droplets can encapsulate nucleic acids with high efficiency, are non-toxic and endosomal escape occurs when formulated with ionizable lipids, as shown by reporter protein translation of an mRNA hosted inside the organelles. We propose that such synthetic microreactors implanted into the cells will become an important bioengineering tool to incorporate more complex and bioorthogonal molecular systems into cells.

synthetic biology↗

ATP-Powered Signaling between Synthetic and Living Cells

ATP is the energy currency of life and overabundant in the tumor microenvironment, where it has been suggested as a target for cancer therapy. We introduce ATP-dissipative delivery of DNA signals from synthetic cells to living cells by exploiting an ATP-driven reaction network that transiently ejects DNA Signal strands from the shielded synthetic cell interior to the extracellular medium of living cells. We customize the Signal for intracellular uptake or for extracellular instruction using a cytokine-ssDNA chimera that can trigger efficient intracellular downstream signaling programs. Our study discusses details of system design on a timer circuit and synthetic cell level, system integration challenges, and how ATP concentrations regulate the transient delivery. The strategy can be extended to deliver therapeutic oligonucleotides for applications in gene therapy and gene silencing. For cancer therapy, it can use naturally enhanced ATP levels to induce selective delivery of therapeutic oligonucleotides.

synthetic biology↗

Synthetic Aptamer Mechanoreceptors Enable Cell-SpecificForce Sensing and Temporal Control via DNA Circuits

Cells interpret mechanical cues from their microenvironment with spatiotemporal precision to guide adaptive behaviors. However, engineering synthetic mechanosensing systems with both cell-specificity and programmability remains challenging, especially when targeting ubiquitous classical mechanoreceptors. Here, we introduce an all-DNA mechanosensing platform based on aptamers that transmit force through noncanonical surface receptors. Aptamer-receptor recognition acts as a molecular gate for force transduction, enabling the design of mechanoprobes with cell-type selectivity. These probes interpret diverse mechanical inputs via distinct mechanisms, including actomyosin-driven contractility and membrane ruffling during macropinocytosis. By integrating aptamer mechanoprobes with upstream DNA reaction networks, we achieve reversible and temporally programmable mechanoresponses. This modular, all-nucleic-acid system offers a general framework for constructing tunable mechanotransduction circuits. It expands the design space for synthetic mechanobiology and provides new opportunities for autonomous, multi-layered mechanical-biochemical regulation in tissue engineering, morphogenesis, and dynamic cell programming.

synthetic biology↗

Leveraging Dynamic Stability to Infer Regulation in Protein-Protein Interaction Networks: A Study of Infectious Vulnerability in COPD.

The fourth leading cause of death in the US, Chronic Obstructive Pulmonary Disease (COPD) is punctuated by frequent viral and bacterial infections causing severe acute exacerbations (AECOPD) and increased mortality. In previous work we have shown that altered immune cell signaling may confer increased and persistent susceptibility to infection. Here we continue this investigation by conducting broad-spectrum proteomic profiling of circulating white blood cells to assemble an empirical protein-protein interaction network associated with frequency of infectious exacerbation. In a novel extension of conventional cross-sectional data analyses, we translate these undirected protein-protein interactions into candidate regulatory relationships with both direction and mode of action. The latter are inferred by formulating and solving a constraint satisfaction problem (SAT) whereby predicted dynamic behaviors of any valid regulatory network must support the expected persistent nature of low and high vulnerability phenotypes. Solving this SAT problem produced a set of competing candidate protein regulatory network architectures and signalling rules that unanimously highlighted several novel candidate pathway elements involved in oxidative stress response. Analysis of the overall dynamics supported by these networks, again supported the hypothesis that progression beyond an immune tipping point may confer persistent susceptibility to infection and that this may constitute a stable phenotype or regulatory trap in COPD characterized by a reactive oxygen cascade. HIGHLIGHTSO_LIInfectious vulnerability phenotypes in COPD may represent immune regulatory traps. C_LIO_LIA 15-protein oxidative stress response interactome offers a phenotypic signature. C_LIO_LIHomeostasis in cross-sectional data can support inference of co-regulatory actions. C_LIO_LI8 of 11 documented regulatory actions recovered in candidate model majority vote C_LIO_LI17 new candidate protein co-regulatory actions proposed unanimously by all models. C_LI

systems biology↗

Nuclease-Resistant L-DNA Tension Probes Enable Long-TermForce Mapping of Single Cells and Cell Consortia

DNA-based tension probes with precisely programmable force response provide important insights into cellular mechanosensing. However, their degradability in cell culture limits their use for long-term imaging, for instance, when cells migrate, divide, and differentiate. This is a critical limitation for providing insights into mechanobiology for these longer-term processes. Here, we present DNA-based tension probes that are entirely designed based on the stereoisomer of biological D-DNA, i.e., L-DNA. We demonstrate that L-DNA tension probes are essentially indestructible by nucleases and provide days-long imaging without significant loss in image quality. We also show their superiority already for short imaging times commonly used for classical D-DNA tension probes. We showcase the potential of these resilient probes to image minute movements, and for generating long term force maps of single cells and for the first time, of collectively migrating cell populations.

biophysics↗

Interplay of kinetochores and catalysts drives rapid assembly of the mitotic checkpoint complex

The spindle assembly checkpoint (SAC) makes mitotic exit contingent on completion of sister chromatid biorientation, but how this coordination is achieved in practice remains poorly understood. Kinetochores, megadalton chromosome attachment sites to spindle microtubules, contribute to SAC signaling. However, it is unclear whether kinetochores are mere docking sites for SAC proteins, or further contribute to co-orientation of SAC catalysts, including MAD1:MAD2 and BUB1:BUB3, to facilitate SAC signaling. Here, we combined biochemical reconstitutions of kinetochores and the SAC to address this question in vitro. We engineered recombinant kinetochore particles that recruit most SAC components and activate SAC signaling after induction with Rapamycin, and challenged them with a battery of impairing mutants. At approximately physiological concentrations of SAC catalysts, kinetochores were crucially required for rapid assembly of the mitotic checkpoint complex (MCC), the SAC effector. Our observations depict kinetochores as a cradle that catalyzes rapid MCC assembly by concentrating and co-orienting distinct SAC catalysts.

biochemistry↗

Neuronal calcium spikes enable vector inversion in the Drosophila brain

A typical neuron signals to downstream cells when it is depolarized and firing sodium spikes. Some neurons, however, also fire calcium spikes when hyperpolarized. The function of such bidirectional signaling remains unclear in most circuits. Here we show how a neuron class that participates in vector computation in the fly central complex employs hyperpolarization-elicited calcium spikes to invert two-dimensional mathematical vectors. By switching from firing sodium to calcium spikes, these neurons implement a [~]180{degrees} realignment between the vector encoded in the neuronal population and the flys internal compass signal, thus inverting the vector. We show that the calcium spikes rely on the T-type calcium channel Ca-1T, and argue, via analytical and experimental approaches, that these spikes enable vector computations in portions of angular space that would otherwise be inaccessible. These results reveal a seamless interaction between molecular, cellular and circuit properties for implementing vector mathematics in the brain.

neuroscience↗

Quantifying Myelin Water Fraction in a Guinea Pig Model of Spontaneous Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is an obstetrical outcome where a fetus has not achieved its genetic potential. A consequence of IUGR is a decrease in brain myelin content. Myelin water imaging (MWI) has previously assessed fetal myelin water fraction (MWF) and can potentially assess myelination changes associated with IUGR. Thus, this study aims to quantify and compare the MWF of non-IUGR and IUGR fetal guinea pigs (GPs) in late gestation. Our sample consisted of 22 pregnant Dunkin-Hartley GPs with 71 fetuses (34 male) [mean {+/-} standard deviation: 60 {+/-} 1.2 days gestation]. Eight SPGR volumes [flip angles (): 2{degrees} - 16{degrees}], and two sets of 8 bSSFP volumes (: 8{degrees} - 64{degrees}), at 0{degrees} and 180{degrees} phase increments were acquired at 3.0 T. MWF maps were generated for each fetal GP brain using multicomponent driven equilibrium single pulse observation of T1/T2 (mcDESPOT). Regions of interest (ROIs) were placed in the fetal corpus callosum (CC), fornix (FOR), and parasagittal white matter (PSW). Linear regression was performed between five fetal IUGR markers [body volume (BV), body-to-pregnancy volume ratio (BPrVR), brain-to-liver VR (BLVR), brain-to-placenta VR (BPlVR), and brain-to-BVR (BBVR)] and MWF for all regions (coefficient of determination, R2). A t-test with a linear mixed model compared the MWF of non-IUGR and IUGR fetal GPs for all three regions ( = 0.05). The MWF values are as follows: (mean {+/-} standard deviation): 0.23 {+/-} 0.02 (fetal CC), 0.19 {+/-} 0.02 (fetal CC - IUGR), 0.31 {+/-} 0.02 (fetal FOR), 0.27 {+/-} 0.01 (fetal FOR - IUGR), 0.28 {+/-} 0.02 (fetal PSW), and 0.24 {+/-} 0.03 (fetal PSW - IUGR). Significant differences in MWF were found between the non-IUGR and IUGR fetuses in every region. In conclusion, the mean MWF of IUGR fetal GPs is significantly lower than non-IUGR fetal GPs.

biophysics↗

Spatial structure does not reduce population level interlocus sexual conflict but imposes additional sex-specific costs

Spatial structure is a common feature of all naturally occurring populations. Theoretically, spatial structuring of a habitat could modulate the intensity of Interlocus sexual conflict (ISC) in a population, possibly by modulating intersexual encounter rate. We tested this theory using laboratory populations of Drosophila melanogaster by measuring male induced fitness decline in females in three-patch habitat systems under two alternative habitat types - structured-interconnected and unstructured. Our results on reproductive and survival costs in females suggested significant costs due to (a) male presence (i.e., ISC) and (b) living on structured habitat. However, there was only a weak evidence supporting the theory of modulation of ISC by habitat structuring only. Through a follow up experiment, we further showed that the effect of habitat on ISC is also robust to the alteration of female conditions. Therefore, it appears that spatial structuring per se is unlikely to modulate ISC, but can impose additional survival costs. We further showed such survival cost could be sex-specific possibly reflecting female biased spontaneous dispersal.

evolutionary biology↗

Pseudogenes limit the identification of novel common transcripts generated by their parent genes

The human genome contains numerous duplicated regions, such as parent-pseudogene pairs, causing sequencing reads to align equally well to either gene. The extent to which this ambiguity complicates transcriptomic analyses is currently unknown. This is concerning as many parent genes have been linked to disease, including GBA1, causally linked to both Parkinsons and Gaucher disease. We find that most of the short sequencing reads that map to GBA1, also map to its pseudogene, GBAP1. Using long-read RNA-sequencing in human brain, where all reads mapped uniquely, we demonstrate significant differences in expression compared to short-read data. We identify novel transcripts from both GBA1 and GBAP1, including protein-coding transcripts that are translated in vitro and detected in proteomic data, but that lack GCase activity. By combining long-read with single-nuclear RNA-sequencing to analyse brain-relevant cell types we demonstrate that transcript expression varies by brain region with cell-type-selectivity. Taken together, these results suggest a non-lysosomal function for both GBA1 and GBAP1 in brain. Finally, we demonstrate that inaccuracies in annotation are widespread among parent genes, with implications for many human diseases.

genetics↗

Molecular Characterisation Of Urine And Vaginal Samples And Their Antibiotic Susceptibility Pattern Associated With β-Lactamases Resistance Gene

Infection or inflammation of the vagina is called vaginitis. The two most common causes of vaginitis are bacterial vaginitis and Candida vaginitis. The causative organisms may be sexually transmitted or endogenous, usually by Gardnerella vaginalis and Mycoplasma hominis in combination with other anaerobes. Urinary tract infections (UTI) refer to the presence of microbial pathogens within the urinary tract and are caused by a range of pathogens but most commonly by Escherichia coli, Klebsiella pneumoniae etc. Highly increase in antibiotic-resistant among uropathogens, including ESBL producing E.coli, AmpC {beta}-lactamase or carbapenemase-producing Enterobacteriaceae (e.g., New Delhi metallo-{beta}-lactamase [NDM]) are being reported among health care unit. Carbapenem-resistant Enterobacteriaceae (CRE) is a growing concern worldwide and a major challenge by the WHO 2014. The aim of this study was to determine the occurrence of CTX-M gene and TEM gene and the possible role of ESBL in resistance to antibiotic. A study was conducted on a total of 100 urine and vaginal samples from Dr. B. Lal clinical laboratory and was cultured on Nutrient Agar and MacConkey agar for the detection of etiologic agents. Bacteria isolation, identification & biochemical characterization was done. Kirby-Bauer Disk Diffusion (KBDS) method was used for detection of ESBL-producing strains. A disc of Cefotaxime (30 {micro}g) and Clavulanic acid (30 {micro}g) were placed at a distance of 20 mm on Muller Hilton agar plate along with Imipenem(30{micro}g), Piperacillin/Tazobactam(10{micro}g) and Ceftazidime(30{micro}g). The zone of inhibition generally greater than 20mm was considered as ESBL producer. Total 14 isolates were identified as ESBL producer. In order to find out the plasmid profile of these isolates, plasmid DNA isolation was done. Isolates was found to have one or more than one plasmid gene responsible for the ESBL resistance. This finding concludes that CTX-M gene is most common gene in ESBL producing isolates. It is highly recommended that antibiotic prescription should be monitored according to guideline. The prevalence of ESBL is increasing day by day and necessary steps should be taken to prevent the spread and emergence of resistance.

microbiology↗

Proteomic network analysis of bronchoalveolar lavage fluid in ex-smokers to discover implicated protein targets and novel drug treatments for chronic obstructive pulmonary disease

RationaleBronchoalveolar lavage of the epithelial lining fluid can sample the profound changes in the airway lumen milieu prevalent in Chronic Obstructive Pulmonary Disease (COPD). Characterizing the proteins in bronchoalveolar lavage fluid in COPD with advanced proteomic methods will identify disease-related changes, provide insight into pathogenetic mechanisms and potential therapeutics that will aid in the discovery of more effective therapeutics for COPD. ObjectivesWe compared epithelial lining fluid proteome of ex-smokers with moderate COPD who are not in exacerbation status COPD, to non-smoking healthy control subjects using advanced proteomics methods and applied proteome-scale translational bioinformatics approaches to identify potential therapeutic protein targets and drugs that modulate these proteins towards the treatment of COPD. MethodsProteomic profiles of bronchalveolar lavage fluid were obtained from 1) never-smoker control subjects with normal lung function (n=10) or 2) individuals with stable moderate (GOLD stage 2, FEV1 50% - 80% predicted) COPD who were ex-smokers for at least one year (n=10). NIHs Database for Annotation, Visualization and Integrated Discovery (DAVID) and Ingenuitys Ingenuity Pathway Analysis (IPA) were the two bioinformatics tools employed for network analysis on the differentially expressed proteins to identify potential crucial hub proteins. The drug-proteome interaction signature comparison and ranking approach implemented in the Computational Analysis of Novel Drug Opportunities (CANDO) platform for multiscale therapeutic discovery was utilized to identify potential repurposable drugs for the treatment of COPD based on the BALF proteome. Subsequently, a literature-based knowledge graph was utilized to rank combinations of drugs that would most likely ameloriate inflammatory processes by inhibition or activation of their functions. ResultsProteomic network analysis demonstrated that 233 of the >1800 proteins identified in the BALF were differentially expressed in COPD versus control, including proteins associated with inflammation, structural elements, and energy metabolism. Functional annotation of the differentially expressed proteins by their implicated biological processes, cellular localization, and transcription factor interactions was accomplished via DAVID. Canonical pathways containing the differential expressed proteins were detailed via the Ingenuity Pathway Analysis application. Topological network analysis demonstrated that four proteins act as central node proteins in the inflammatory pathways in COPD. The CANDO multiscale drug discovery platform was used to analyze the behavioral similarity between the interaction signatures of all FDA-approved drugs and the identified BALF proteins. The drugs with the signatures most similar interaction signatures to approved COPD drugs were extracted with the CANDO platform. The analysis revealed 189 drugs that putatively target the proteins implicated in COPD. The putative COPD drugs that were identified using CANDO were subsequently analyzed using a knowledge based technique to identify an optimal two drug combination that had the most appropriate effect on the central node proteins. ConclusionAnalysis of the BALF proteome revealed novel differentially expressed proteins in the epithelial lining fluid that elucidate COPD pathogenesis. Network analyses identified critical targets that have critical roles in modulating COPD pathogenesis, for which we identified several drugs that could be repurposed to treat COPD using a multiscale shotgun drug discovery approach.

bioinformatics↗

Detection of pathogenic splicing events from RNA-sequencing data using dasper

Although next-generation sequencing technologies have accelerated the discovery of novel gene-to-disease associations, many patients with suspected Mendelian diseases still leave the clinic without a genetic diagnosis. An estimated one third of these patients will have disorders caused by mutations impacting splicing. RNA-sequencing has been shown to be a promising diagnostic tool, however few methods have been developed to integrate RNA-sequencing data into the diagnostic pipeline. Here, we introduce dasper, an R/Bioconductor package that improves upon existing tools for detecting aberrant splicing by using machine learning to incorporate disruptions in exon-exon junction counts as well as coverage. dasper is designed for diagnostics, providing a rank-based report of how aberrant each splicing event looks, as well as including visualization functionality to facilitate interpretation. We validate dasper using 16 patient-derived fibroblast cell lines harbouring pathogenic variants known to impact splicing. We find that dasper is able to detect pathogenic splicing events with greater accuracy than existing LeafCutterMD or z-score approaches. Furthermore, by only applying a broad OMIM gene filter (without any variant-level filters), dasper is able to detect pathogenic splicing events within the top 10 most aberrant identified for each patient. Since using publicly available control data minimises costs associated with incorporating RNA-sequencing into diagnostic pipelines, we also investigate the use of 504 GTEx fibroblast samples as controls. We find that dasper leverages publicly available data effectively, ranking pathogenic splicing events in the top 25. Thus, we believe dasper can increase diagnostic yield for a pathogenic splicing variants and enable the efficient implementation of RNA-sequencing for diagnostics in clinical laboratories.

bioinformatics↗

Leveraging omic features with F3UTER enables identification of unannotated 3'UTRs for synaptic genes

There is growing evidence for the importance of 3 untranslated region (3UTR) dependent regulatory processes. However, our current human 3UTR catalogue is incomplete. Here, we developed a machine learning-based framework, leveraging both genomic and tissue-specific transcriptomic features to predict previously unannotated 3UTRs. We identify unannotated 3UTRs associated with 1,513 genes across 39 human tissues, with the greatest abundance found in brain. These unannotated 3UTRs were significantly enriched for RNA binding protein (RBP) motifs and exhibited high human lineage-specificity. We found that brain-specific unannotated 3UTRs were enriched for the binding motifs of important neuronal RBPs such as TARDBP and RBFOX1, and their associated genes were involved in synaptic function and brain- related disorders. Our data is shared through an online resource F3UTER (https://astx.shinyapps.io/F3UTER/). Overall, our data improves 3UTR annotation and provides novel insights into the mRNA-RBP interactome in the human brain, with implications for our understanding of neurological and neurodevelopmental diseases.

bioinformatics↗

Subcellular mRNA localization and local translation of Arhgap11a in radial glial cells regulates cortical development

mRNA localization and local translation enable exquisite spatial and temporal control of gene expression, particularly in highly polarized and elongated cells. These features are especially prominent in radial glial cells (RGCs), which serve as neural and glial precursors of the developing cerebral cortex, and scaffolds for migrating neurons. Yet the mechanisms by which distinct sub-cellular compartments of RGCs accomplish their diverse functions are poorly understood. Here, we demonstrate that subcellular RNA localization and translation of the RhoGAP Arhgap11a controls RGC morphology and mediates cortical cytoarchitecture. Arhgap11a mRNA and protein exhibit conserved localization to RGC basal structures in mice and humans, conferred by a 5'UTR cis-element. Proper RGC morphology relies upon active Arhgap11a mRNA transport and localization to basal structures, where ARHGAP11A is locally synthesized. Thus, RhoA activity is spatially and acutely activated via local translation in RGCs to promote neuron positioning and cortical cytoarchitecture. Altogether, our study demonstrates that mRNA localization and local translation mediate compartmentalization of neural progenitor functions to control brain development. HighlightsO_LIArhgap11a in radial glia non-cell autonomously promotes neuronal migration and lamination C_LIO_LIArhgap11a mRNA localizes to radial glial endfeet via a 5 UTR cis element C_LIO_LIARHGAP11A expression in basal process and endfeet depends upon its localized mRNA C_LIO_LILocalized mRNA and RhoA-GAP activity in endfeet control radial glial morphology C_LI

neuroscience↗

Postmitotic Nuclear Pore Assembly Proceeds By Radial Dilation Of Small ER Membrane Openings

The nuclear envelope has to be reformed after mitosis to create viable daughter cells with closed nuclei. How membrane sealing of DNA and assembly of nuclear pore complexes (NPCs) are achieved and coordinated is poorly understood. Here, we reconstructed nuclear membrane topology and structure of assembling NPCs in a correlative three dimensional electron microscopy time-course of dividing human cells. Our quantitative ultrastructural analysis shows that nuclear membranes form from highly fenestrated ER sheets, whose shrinking holes are stabilized and then dilated into NPCs during inner ring complex assembly, forming thousands of transport channels within minutes. This mechanism is fundamentally different from interphase NPC assembly and explains how mitotic cells can rapidly establish a closed nuclear compartment while making it transport-competent at the same time.

cell biology↗