Biology subjects

Betts, J.

Publications and source records attributed to Betts, J..

7 recordsLinked to original sources

bioRxiv2025

Characterization of genetically novel chimeric plasmids from Salmonella Heidelberg conferring multi-drug resistance and increased pathogenicity

Salmonella enterica serotype Heidelberg (S. Heidelberg) is a significant cause of human salmonellosis, with resistance to extended-spectrum cephalosporins posing challenges for clinical management. In this study, we genetically and functionally characterized six plasmids isolated from distinct PFGE-types of S. Heidelberg previously reported in The Netherlands, revealing a chimeric IncC-I1a plasmid that shares similarities with the epidemic pESI plasmid identified in emergent S. Infantis isolates. Our analysis showed the accumulation of genetic determinants conferring resistance to antibiotics (blaCMY-2, tetA and sul2) and heavy metals (mer operon), as well as enhanced pathogenicity (Yersinia high-pathogenicity island). All these elements are located on a stable non-conjugative but likely mobilizable plasmid backbone that imposes only a marginal fitness cost on its bacterial host. This convergence of multidrug resistance and pathogenicity likely enhances bacterial adaptability and virulence, undermining control strategies based solely on reducing selective pressure. The emergence and dissemination of such hybrid plasmids represent an increasing threat to both public and animal health, analogous to that posed by pESI-like plasmids, and underscore the urgent need for integrated genomic surveillance and risk assessment, as their continued expansion could complicate antimicrobial therapy and containment efforts during Salmonella outbreaks.

microbiology↗

bioRxiv2023

Selective IL-27 production by intestinal regulatory T cells permits gut-specific regulation of Th17 immunity

Regulatory T (Treg) cells are instrumental in establishing immunological tolerance. However, the precise effector mechanisms by which Treg cells control a specific type of immune response in a given tissue remains unresolved. By simultaneously studying Treg cells from different tissue origins under systemic autoimmunity, here we show that IL-27 is specifically produced by intestinal Treg cells to regulate Th17 immunity. Selectively increased intestinal Th17 responses in mice with Treg cell-specific IL-27 ablation led to exacerbated intestinal inflammation and colitis-associated cancer, but also helped protect against enteric bacterial infection. Furthermore, single-cell transcriptomic analysis has identified a CD83+TCF1+ Treg cell subset that is distinct from previously characterized intestinal Treg cell populations as the main IL-27 producers. Collectively, our study uncovers a novel Treg cell suppression mechanism crucial for controlling a specific type of immune response in a particular tissue, and provides further mechanistic insights into tissue-specific Treg cell-mediated immune regulation.

immunology↗

bioRxiv2022

A structural basis for prion strain diversity

Recent cryo-EM studies of infectious, ex vivo, prion fibrils from hamster 263K and mouse RML prion strains revealed a comparable, parallel in-register intermolecular {beta}-sheet (PIRIBS) amyloid architecture. Rungs of the fibrils are composed of individual prion protein (PrP) monomers that fold to create distinct N- and C-terminal lobes. However, disparity in the hamster/mouse PrP sequence precludes understanding how divergent prion strains emerge from an identical PrP substrate. Here, we determined the near-atomic resolution cryo-EM structure of infectious, ex vivo mouse prion fibrils from the ME7 prion strain and have compared this with the RML fibril structure. This structural comparison of two biologically distinct mouse-adapted prion strains suggests defined folding sub-domains of PrP rungs and the way in which they are interrelated, providing the first structural definition of intra-species prion strain-specific conformations.

biochemistry↗

bioRxiv2021

2.7 A cryo-EM structure of ex vivo RML prion fibrils

Mammalian prions are lethal infectious agents that propagate as distinct strains and are composed of multichain assemblies of misfolded host-encoded prion protein (PrP), often referred to as prion rods. The structural features that define infectious prion rods and the molecular determinants of prion strain diversity are poorly understood. Here, we present a near-atomic resolution cryo-EM structure of PrP fibrils present in highly infectious prion rod preparations isolated from the brains of RML prion-infected mice. We found that prion rods comprise single-protofilament helical amyloid fibrils that coexist with twisted pairs of the same protofilaments. Each rung of the protofilament is formed by a single PrP monomer with the ordered core comprising PrP residues 94-225, which folds to create two asymmetric lobes with the N-linked glycans and the glycosylphosphatidylinositol anchor projecting from the C-terminal lobe. The overall architecture is comparable to that of recently reported PrP fibrils isolated from the brain of hamsters infected with the 263K prion strain. However, there are marked conformational variations that could result from differences in PrP primary sequence and/or represent distinguishing features of the distinct prion strains. These conformational changes impact the overall geometry of the fibrils and may also impact fibril pairing, one or both of which may critically influence PrP glycoform selection that occurs during strain-specific prion propagation.

biochemistry↗

bioRxiv2019

Lipid metabolism links nutrient-exercise timing to insulin sensitivity in men classified as overweight or obese.

ContextPre-exercise nutrient availability alters acute metabolic responses to exercise, which could modulate training responsiveness. We hypothesised that in men with overweight/obesity, acute exercise before versus after nutrient ingestion would increase whole-body and intramuscular lipid utilization, translating into greater increases in oral glucose insulin sensitivity over 6-weeks of training.\n\nDesign and ParticipantsWe showed in men with overweight/obesity (mean{+/-}SD for BMI: 30.2{+/-}3.5 kgxm-2 for acute, crossover study, 30.9{+/-}4.5 kgxm-2 for randomized, controlled, training study) a single exercise bout before versus after nutrient provision increased lipid utilisation at the whole-body level, but also in both type I (p<0.01) and type II muscle fibres (p=0.02). We then used a 6-week training intervention to show sustained, 2-fold increases in lipid utilisation with exercise before versus after nutrient provision (p<0.01).\n\nMain Outcome MeasuresPostprandial glycemia was not differentially affected by exercise training before vs after nutrient provision (p>0.05), yet plasma was reduced with exercise training before, but not after nutrient provision (p=0.03), resulting in increased oral glucose insulin sensitivity when training was performed before versus after nutrient provision (25{+/-}38 vs -21{+/-}32 mLxmin-1xm-2; p=0.01) and this was associated with increased lipid utilisation during exercise (r=0.50, p=0.02). Regular exercise prior to nutrient provision augmented remodelling of skeletal muscle phospholipids and protein content of the glucose transport protein GLUT4 (p<0.05).\n\nConclusionsExperiments investigating exercise training and metabolic health should consider nutrient-exercise timing, and exercise performed before versus after nutrient intake (i.e., in the fasted state) may exert beneficial effects on lipid utilisation and reduce postprandial insulinemia.\n\nPrecisExercise in the fasted-versus fed-state increased intramuscular and whole-body lipid use, translating into increased muscle adaptation and insulin sensitivity when regularly performed over 6 weeks.

physiology↗

bioRxiv2019

Highly efficient genome editing in primary bronchial epithelial cells establishes FOXJ1 as essential for ciliation in human airways

The structure and composition of the bronchial epithelium is altered in respiratory diseases such as COPD and asthma, in which goblet cell hyperplasia and reduced numbers of ciliated cells impair mucociliary clearance. We describe a robust genome editing pipeline to interrogate modulators of primary human bronchial epithelial cell (HBEC) differentiation and function. By employing plasmid- and virus-free delivery of CRISPR/Cas9 to human airway basal cells we achieve highly efficient gene inactivation without the need for positive selection. Genome edited cells are differentiated at air liquid interface (ALI) into a pseudo-stratified epithelium. We focus on profiling ciliation using imaging cytometry coupled to confocal microscopy and immunohistochemistry. To our knowledge, this is the first study to describe highly efficient genome editing of ALI cultured primary HBECs. As proof of concept, we establish that inactivation of the gene encoding the transcription factor FOXJ1 in primary human airway basal cells precludes ciliation in ALI differentiated bronchial epithelia.

molecular biology↗

bioRxiv2018

Single step, high efficiency CRISPR-Cas9 genome editing in primary human disease-derived fibroblasts

Genome editing is a tool that has many applications including the validation of potential drug targets. However, performing genome editing in low passage, primary human cells with the greatest physiological relevance, is notoriously difficult. High editing efficiency is desired because it enables gene knock outs (KO) to be generated in bulk cellular populations and circumvents the problem of having to generate clonal cell isolates. Here, we describe a single step workflow enabling >90% KO generation in primary human lung fibroblasts via CRISPR ribonucleoprotein delivery, in the absence of antibiotic selection or clonal expansion. As proof of concept, we performed a disease relevant phenotypic assay measuring collagen deposition in response to TGF{beta} and demonstrated SMAD3 but not SMAD2 dependent deposition of type I collagen following knockout of each using our single step methodology. The optimization of this workflow can readily be transferred to other primary cell types.

molecular biology↗