Biology subjects

Barrington, C.

Publications and source records attributed to Barrington, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Genomic history and selection in Roman and early medieval Britain

Leading biomedical resources rely on genome variation in Britain1-3, but the historical processes that shaped present-day fine-scale diversity remain debated4-13. Here we sequenced 1039 ancient shotgun genomes from Britain (median 1.4-fold coverage), primarily dating to the first millennium CE. We imputed [~]660 million variants in the UK Biobank14-16 and employed genealogy-based ancestry reconstruction. We found an association between Iron Age consanguinity and matrilineal burial practices17, later disrupted following the Roman Conquest. Despite this societal impact, only 20% of Roman-period individuals carried detectable ancestry from outside Britain. In contrast, from the 6th century CE we detect widespread influx of ancestry in over 70% of individuals in southernAnglo-Saxon Britain, with limited local admixture. We find previously underappreciated heterogeneity, with ancestries associated with Central and Southern Europe rising in prevalence from the 7th century CE. We demonstrate distinct Scandinavian-related ancestry in many Viking-associated contexts, but show that the population-level impact of the Viking Age in Britain was limited. Finally, we detect pre-medieval selection on variants linked with key immunity genes TLR10-TLR1 and IRF8. These results identify population-level and selective processes that shape variation and disease risk in Britain today.

genomics↗

bioRxiv2026

Contribution of cytotoxic CD8 T cells, neutrophils and type 1 interferon signaling to hyperinflammatory pathology in HIV associated TB meningitis

Immune dysregulation contributes to death and disability in tuberculous meningitis. People living with HIV have the least evidence that anti-inflammatory therapy improves the poor outcome. Improving therapy relies on a more refined understanding of the host immune response. Single-cell RNA sequencing of 188,983 CSF cells from 25 adults with HIV-associated TBM revealed a predominance of cytotoxic CD8 T cells with low cytokine expression. In microbiologically-confirmed TBM, there was greater cytotoxicity in T, NK and {gamma}{delta} cells, and higher type 1 interferon stimulation in T and B lymphocytes. Neutrophils expressed markers suggesting heightened cytokine stimulation, enhanced effector function, and IL-8-mediated neutrophil recruitment. In a longitudinal cohort, type 1 interferon signaling increased in blood and CSF following treatment initiation. Overall, findings indicate a hyper-inflammatory immune response in the CSF of HIV-associated TBM patients characterised by an accumulation of granzyme-rich cytotoxic CD8 T cells, highly activated neutrophils and host-detrimental type 1 interferon signaling.

immunology↗

bioRxiv2025

Beneficial and detrimental consequences of AHR activation in intestinal infection

The ligand dependent transcription factor aryl hydrocarbon receptor (AHR) is an environmental sensor whose activation can have physiologically beneficial or detrimental consequences for host immune responses depending on the ligand. Here we investigated the hypothesis that prolonged AHR activation either due to inefficient ligand metabolism or due to genetic manipulation may underlie the distinction between beneficial and detrimental effects. Our data indicate that prolonged AHR activation caused toxic endpoints for liver and thymus but was not per se interfering with the host response to infection with the intestinal pathogen C.rodentium. Genetically driven constitutive AHR activation improved resistance to infection, whereas prolonged AHR activation by the pollutant TCDD resulted in delayed clearance of C.rodentium associated with a suppression in antibody production. Combined single cell RNAseq and ATAC-seq analysis provided evidence that TCDD, but not genetic AHR activation, negatively affected dendritic cell functions such as activation, maturation and antigen presentation. Thus, the detrimental impact of environmental pollutants such as TCDD on immune responses cannot solely be attributed to aberrantly prolonged activation of AHR.

immunology↗

bioRxiv2025

An intercellular metabolic relay for brain sparingin Drosophila

Brain sparing protects growth of the central nervous system (CNS) at the expense of other developing organs during nutrient restriction. This survival strategy is conserved from Drosophila to mammals but little is known about its underlying metabolic mechanisms. Here, we show that CNS uptake and catabolism of circulating glutamine is essential for neural stem cell proliferation during brain sparing but not normal brain development. Glutamine is imported into perineurial glia of the blood-brain-barrier, which upregulate glutaminase (Gls) and vesicular glutamate transporter 1 (VGlut1) to promote glutaminolysis and glutamate secretion. Neural stem cells then import released glutamate via excitatory amino acid transporter 1 (Eaat1) and maintain it at homeostatic levels via glutamine synthetase 1 (Gs1). Glutamine nitrogen contributes surprisingly little to newly synthesized DNA or protein in neural stem cells but its carbon fuels the oxidative tricarboxylic acid cycle. These findings identify an intercellular metabolic relay specifically required to sustain the proliferation of neural stem cells during brain sparing.

developmental biology↗

bioRxiv2024

Comparative analysis of 43 distinct RNA modifications by nanopore tRNA sequencing

Transfer RNAs are the fundamental adapter molecules of protein synthesis and the most abundant and heterogeneous class of noncoding RNA molecules in cells. The study of tRNA repertoires remains challenging, complicated by the presence of dozens of post transcriptional modifications. Nanopore sequencing is an emerging technology with promise for both tRNA sequencing and the detection of RNA modifications; however, such studies have been limited by the throughput and accuracy of direct RNA sequencing methods. Moreover, detection of the complete set of tRNA modifications by nanopore sequencing remains challenging. Here we show that recent updates to nanopore direct RNA sequencing chemistry (RNA004) combined with our own optimizations to tRNA sequencing protocols and analysis workflows enable high throughput coverage of tRNA molecules and characterization of nanopore signals produced by 43 distinct RNA modifications. We share best practices and protocols for nanopore sequencing of tRNA and further report successful detection of low abundance mitochondrial and viral tRNAs, providing proof of concept for use of nanopore sequencing to study tRNA populations in the context of infection and organelle biology. This work provides a roadmap to guide future efforts towards de novo detection of RNA modifications across multiple organisms using nanopore sequencing.

molecular biology↗

bioRxiv2024

Ancient Borrelia genomes document the evolutionary history of louse-borne relapsing fever

Several disease-causing bacteria have transitioned from tick-borne to louse-borne transmission, a process associated with increased virulence and genome reduction. However, the historical time frame and speed of such evolutionary transitions have not been documented with ancient genomes. Here, we discover four ancient cases of Borrelia recurrentis, the causative agent of louse-borne relapsing fever, in Britain between [~]600 and 2,300 years ago, and sequence whole genomes up to 29-fold coverage. We estimate a recent divergence from the closest tick-borne ancestor, likely within the last [~]8,000 years. We reconstruct a chronology of gene losses and acquisitions using the pan-genome of related species, and show that almost all of the reductive evolution observed in B. recurrentis had occurred by [~]2,000 years ago, and was thus a rapid process after divergence. Our observations provide a new understanding of the origins of B. recurrentis and document complex reductive evolution in a specialist vector-borne pathogen.

evolutionary biology↗

bioRxiv2024

North Pontic crossroads: Mobility in Ukraine from the Bronze Age to the early modern period

The North Pontic region, which encompasses present-day Ukraine, was a crossroads of migration as it connected the vast Eurasian Steppe with Central Europe. We generated shotgun-sequenced genomic data for 91 individuals dating from around 7,000 BCE to 1,800 CE to study migration and mobility history in the region, with a particular focus on historically attested migrating groups during the Iron Age and the medieval period, such as Scythian, Chernyakhiv, Saltiv and Nogai associated peoples. We infer a high degree of temporal heterogeneity in ancestry, with fluctuating genetic affinities to present-day Western European, Eastern European, Western Steppe and East Asian groups. We also infer high heterogeneity in ancestry within geographically, culturally and socially defined groups. Despite this, we find that ancestry components which are widespread in Eastern and Central Europe have been present in the Ukraine region since the Bronze Age.

genomics↗

bioRxiv2024

Marsupial single-cell transcriptomics provides an atlas of developmental heterochrony

Single-cell transcriptomics has revealed conserved and divergent programmes of organogenesis in mammals, but existing studies have focused on eutherians. Marsupials exhibit short gestation and complete development externally, necessitating accelerated differentiation of anterior features required for locomotion and feeding. As such, they represent a unique outgroup with which to understand temporal shifts in development, known as heterochrony. Here, we generate the first single-cell transcriptomic atlas of gastrulation and early organogenesis in a marsupial, the opossum Monodelphis domestica. We find that anterior prioritisation is achieved by earlier initiation and shorter duration of transcriptional programmes relative to eutherians. The result is uncoupling of transcriptional and morphological progression, revealing unforeseen diversity in the order of developmental sequences in mammals. We uncover novel tissues for which heterochrony has not previously been documented. Our findings indicate that accelerated activation of transcriptional programmes facilitates the rapid growth needed for survival of the marsupial neonate.

developmental biology↗

bioRxiv2024

High-resolution genomic ancestry reveals mobility in early medieval Europe

Ancient DNA has unlocked new genetic histories and shed light on archaeological and historical questions, but many known and unknown historical events have remained below detection thresholds because subtle ancestry changes are challenging to reconstruct. Methods based on sharing of haplotypes1,2 and rare variants3,4 can improve power, but are not explicitly temporal and have not been adopted in unbiased ancestry models. Here, we develop Twigstats, a new approach of time-stratified ancestry analysis that can improve statistical power by an order of magnitude by focusing on coalescences in recent times, while remaining unbiased by population-specific drift. We apply this framework to 1,151 available ancient genomes, focussing on northern and central Europe in the historical period, and show that it allows modelling of individual-level ancestry using preceding genomes and provides previously unavailable resolution to detect broader ancestry transformations. In the first half of the first millennium [~]1-500 CE (Common Era), we observe an expansion of Scandinavian-related ancestry across western, central, and southern Europe. However, in the second half of the millennium [~]500-1000 CE, ancestry patterns suggest the regional disappearance or substantial admixture of these ancestries in multiple regions. Within Scandinavia itself, we document a major ancestry influx by [~]800 CE, when a large proportion of Viking Age individuals carried ancestry from groups related to continental Europe. This primarily affected southern Scandinavia, and was differentially represented in the western and eastern directions of the wider Viking world. We infer detailed ancestry portraits integrated with historical, archaeological, and stable isotope evidence, documenting mobility at an individual level. Overall, our results are consistent with substantial mobility in Europe in the early historical period, and suggest that time-stratified ancestry analysis can provide a new lens for genetic history.

evolutionary biology↗

bioRxiv2023

Cohesin chromatin loop formation by an extrinsic motor

The ring-shaped cohesin complex topologically entraps two DNAs to establish sister chromatid cohesion1-3. Cohesin also shapes the interphase chromatin landscape with wide-ranging implications for gene regulation4-7, which cohesin is thought to achieve by actively extruding DNA loops without topologically entrapping DNA8-11. The loop extrusion hypothesis finds motivation from in vitro observations12-14 - whether this process underlies in vivo chromatin loop formation remains untested. Here, using the budding yeast S. cerevisiae, we generate cohesin variants that have lost their ability to extrude DNA loops but retain their ability to topologically entrap DNA. Analysis of these variants suggests that in vivo chromatin loops form independently of loop extrusion. Instead, we find that transcription promotes loop formation, as well as acts as an extrinsic motor that expands these loops and defines their ultimate positions. Our results necessitate a re-evaluation of the loop extrusion model and point to an alternative mechanism for cohesin-dependent chromatin organisation. We propose that cohesin, akin to sister chromatid cohesion establishment at replication forks, forms chromatin loops by DNA-DNA capture at places of transcription, thus unifying cohesins two roles in chromosome segregation and interphase genome organisation.

molecular biology↗

bioRxiv2023

Telomere protein arrays stall DNA loop extrusion by condensin

DNA loop extrusion by SMC proteins is a key process underlying chromosomal organization. It is unknown how loop extruders interact with telomeres where chromosome ends are covered with a dense array of tens of neighboring DNA-binding proteins. Using complementary in vivo and in vitro single-molecule approaches, we study the interaction between loop-extruding condensin and arrays of Rap1, the double-stranded-DNA-binding telomeric protein of Saccharomyces cerevisiae. We show that dense linear Rap1 arrays can completely halt DNA loop extrusion, where the blocking efficiency depends on the array length and the DNA gap size between neighboring proteins. In cells, Rap1 arrays in the chromosome are found to act as contact insulators and to accumulate condensin at their borders, with direct implications for the resolution of dicentric chromosomes produced by telomere fusions. Our findings show that linear arrays of DNA-bound proteins can efficiently halt DNA loop extrusion by SMC proteins, which may impact a wide range of cellular processes from telomere functions to transcription and DNA repair.

molecular biology↗

bioRxiv2023

Gastruloid-derived Primordial Germ Cell-like Cells (Gld-PGCLCs) develop dynamically within integrated tissues

Primordial Germ Cells (PGCs) are the early embryonic precursors of gametes - sperm and egg cells. PGC-like cells (PGCLCs) can currently be derived in vitro from pluripotent cells exposed to signalling cocktails and aggregated into large embryonic bodies, but these do not recapitulate the native embryonic environment during PGC formation. Here we show that mouse gastruloids, a three-dimensional in vitro model of gastrulation, contain a population of Gastruloid-derived PGC-like cells (Gld-PGCLCs) that resemble early PGCs in vivo. Importantly, the conserved organisation of mouse gastruloids leads to coordinated spatial and temporal localisation of Gld-PGCLCs relative to surrounding somatic cells, even in the absence of specific exogenous PGC-specific signalling or extraembryonic tissues. In gastruloids, self-organised interactions between cells and tissues, including the endodermal epithelium, enables the specification and subsequent maturation of a pool of Gld-PGCLCs. As such, mouse gastruloids represent a new source of PGCLCs in vitro and, due to their inherent co-development, serve as a novel model to study the dynamics of PGC development within integrated tissue environments.

developmental biology↗

bioRxiv2022

PKN2 deficiency leads both to prenatal congenital cardiomyopathy and defective angiotensin II stress responses.

BackgroundThe protein kinase PKN2 is required for embryonic development, and PKN2 knockout mice die as a result of failure in expansion of mesoderm tissues, cardiac development and neural tube closure. In the adult, cardiomyocyte PKN2 and PKN1 (in combination) are required for cardiac adaptation to pressure-overload. The role of PKN2 in contractile cardiomyocytes during development and its role in the adult heart remain to be fully established. MethodsWe used mice with cardiomyocyte-directed knockout of PKN2 or global PKN2 haploinsufficiency. Cardiac function and dimensions were assessed with high resolution episcopic microscopy, MRI, micro-CT and echocardiography. Biochemical and histological changes were assessed. ResultsCardiomyocyte-directed PKN2 knockout embryos displayed striking abnormalities in the compact myocardium, with frequent myocardial clefts and diverticula, ventricular septal defects and abnormal heart shape. The sub-Mendelian homozygous knockout survivors developed cardiac failure. RNASeq data showed upregulation of PKN2 in patients with dilated cardiomyopathy, suggesting an involvement in adult heart disease. Given the rarity of homozygous survivors with cardiomyocyte-specific deletion of PKN2, this was explored using mice with constitutive heterozygous PKN2 knockout. Cardiac hypertrophy resulting from hypertension induced by angiotensin II was reduced in haploinsufficient PKN2 mice relative to wild-type littermates, with suppression of cardiomyocyte hypertrophy and cardiac fibrosis. ConclusionsCardiomyocyte PKN2 is essential for heart development and formation of compact myocardium, and is also required for cardiac hypertrophy in hypertension. Thus, PKN signalling may offer therapeutic options for managing congenital and adult heart diseases.

developmental biology↗

bioRxiv2021

A novel enhancer that regulates Bdnf expression in developing neurons

Brain derived neurotrophic factor (BDNF) is a critical secreted peptide that promotes neuronal differentiation and survival, and its downregulation is implicated in many neurological disorders. Here, we investigated the regulation of the mouse Bdnf gene in cortical neurons and identified a novel enhancer that promotes the expression of many Bdnf transcript variants during differentiation, increasing total Bdnf mRNA levels. Enhancer activity contributes to Bdnf-mediated effects on neuronal clustering and activity-dependent dendritogenesis. During Bdnf activation, enhancer-promoter contacts increase, and the region moves away from the repressive nuclear periphery. Our findings suggest that changes in nuclear structure may contribute to the expression of essential growth factors during neuronal development.

molecular biology↗

bioRxiv2021

Single cell transcriptome profiling of the human developing spinal cord reveals a conserved genetic programme with human specific features

The spinal cord receives input from peripheral sensory neurons and controls motor output by regulating muscle innervating motor neurons. These functions are carried out by neural circuits comprising molecularly and physiologically distinct neuronal subtypes that are generated in a characteristic spatial-temporal arrangement from progenitors in the embryonic neural tube. The systematic mapping of gene expression in mouse embryos has provided insight into the diversity and complexity of cells in the neural tube. For human embryos, however, less information has been available. To address this, we used single cell mRNA sequencing to profile cervical and thoracic regions in four human embryos of Carnegie Stages (CS) CS12, CS14, CS17 and CS19 from Gestational Weeks (W) 4-7. In total we recovered the transcriptomes of 71,219 cells. Analysis of progenitor and neuronal populations from the neural tube, as well as cells of the peripheral nervous system, in dorsal root ganglia adjacent to the neural tube, identified dozens of distinct cell types and facilitated the reconstruction of the differentiation pathways of specific neuronal subtypes. Comparison with existing mouse datasets revealed the overall similarity of mouse and human neural tube development while highlighting specific features that differed between species. These data provide a catalogue of gene expression and cell type identity in the developing neural tube that will support future studies of sensory and motor control systems and can be explored at https://shiny.crick.ac.uk/scviewer/neuraltube/.

developmental biology↗

bioRxiv2020

Computational and experimental analyses of mitotic chromosome formation pathways in fission yeast

Underlying higher order chromatin organization are Structural Maintenance of Chromosomes (SMC) complexes, large protein rings that entrap DNA. The molecular mechanism by which SMC complexes organize chromatin is as yet incompletely understood. Two prominent models posit that SMC complexes actively extrude DNA loops (loop extrusion), or that they sequentially entrap two DNAs that come into proximity by Brownian motion (diffusion capture). To explore the implications of these two mechanisms, we perform biophysical simulations of a 3.76 Mb-long chromatin chain, the size of the long S. pombe chromosome I left arm. On it, the SMC complex condensin is modeled to perform loop extrusion or diffusion capture. We then compare computational to experimental observations of mitotic chromosome formation. Both loop extrusion and diffusion capture can result in native-like contact probability distributions. In addition, the diffusion capture model more readily recapitulates mitotic chromosome axis shortening and chromatin density enrichment. Diffusion capture can also explain why mitotic chromatin shows reduced, as well as more anisotropic, movements, features that lack support from loop extrusion. The condensin distribution within mitotic chromosomes, visualized by stochastic optical reconstruction microscopy (STORM), shows clustering predicted from diffusion capture. Our results inform the evaluation of current models of mitotic chromosome formation.

biophysics↗

bioRxiv2020

The Casein Kinase II catalytic subunit CSNK2A1 interacts with TTBK2 to regulate ciliary trafficking and stability

Cilia biogenesis is a complex, multi-step process involving the coordination of multiple cellular trafficking pathways. Despite the importance of ciliogenesis in mediating the cellular response to cues from the microenvironment, we have only a limited understanding of the regulation of cilium assembly. We previously identified a kinase that acts as a key regulator of ciliogenesis, TTBK2. Here, using CRISPR kinome screening, we identify the CK2 subunit CSNK2A1 as an important modulator of TTBK2 function in cilia trafficking. Super-resolution microscopy reveals that CSNK2A1 is a centrosomal protein concentrated at the mother centriole and associated with the distal appendages where it physically interacts with TTBK2. Further, Csnk2a1 knockout partially corrects defects in cilia formation and length in Ttbk2 hypomorphic cells. Csnk2a1 mutant cilia are longer than those of control cells and exhibit instability, particularly at the tip. Csnk2a1 mutant cilia also abnormally accumulate key cilia assembly and SHH-related proteins including IFT, GLI2, KIF7, and Smoothened (SMO). De novo mutations of Csnk2a1 were recently linked to the human genetic disorder Okur-Chung neurodevelopmental syndrome (OCNDS). Consistent with the role of CSNK2A1 in cilium stability, we find that expression of OCNDS-associated Csnk2a1 variants in wild-type cells cause ciliary structural defects. Our findings provide new insights into mechanisms involved in ciliary length regulation, trafficking, and stability that in turn shed light on the significance and implications of cilia instability in human disease. SIGNIFICANCE STATEMENTPrimary cilia (PC) are sensory organelles that play essential roles during development and adulthood. Abnormal functioning of PC causes human disorders called ciliopathies. Hence, a thorough understanding of the molecular regulation of PC is critical. Our findings highlight CSNK2A1 as a novel modulator of cilia trafficking and stability, tightly related to TTBK2 function. Enriched at the centrosome, CSNK2A1 prevents abnormal accumulation of key ciliary proteins, instability at the tip, and aberrant activation of the Sonic Hedgehog pathway. Further, we establish that Csnk2a1 mutations associated with Okur-Chung neurodevelopmental disorder (OCNDS) alter cilia morphology. Thus, we report a potential linkage between CSNK2A1 ciliary function and OCNDS.

cell biology↗

bioRxiv2020

RNA matchmaking remodels lncRNA structure and promotes PRC2 activity

Human Polycomb Repressive Complex 2 (PRC2) catalysis of histone H3 lysine 27 methylation at certain loci depends on long noncoding RNAs (lncRNAs). Yet, in apparent contradiction, RNA is a potent catalytic inhibitor of PRC2. Here we show that intermolecular RNA-RNA interactions between the lncRNA HOTAIR and its target genes can relieve RNA inhibition of PRC2. RNA matchmaking is promoted by heterogenous nuclear ribonucleoprotein (hnRNP) B1, which uses multiple protein domains to bind regions of HOTAIR via multi-valent protein-RNA interactions. Chemical probing demonstrates that RNA matchmaking changes HOTAIR RNA structure. Genome-wide HOTAIR/PRC2 activity occurs at genes whose transcripts can make favorable RNA-RNA interactions with HOTAIR. We demonstrate that RNA-RNA matches of HOTAIR with target gene RNAs can relieve the inhibitory effect of a single lncRNA for PRC2 activity. Our work highlights an intrinsic switch that allows PRC2 activity in specific RNA contexts, which could explain how many lncRNAs work with PRC2.

biochemistry↗