Publications by authors named "Holroyd N"

Studies on transcription regulation in platyhelminth development are scarce, especially for parasitic flatworms. Here, we employed single-cell transcriptomics to identify genes involved in reproductive development in the trematode model Schistosoma mansoni. This parasite causes schistosomiasis, a major neglected infectious disease affecting >240 million people worldwide.

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Disruption of retinal vasculature is linked to various diseases, including diabetic retinopathy and macular degeneration, leading to vision loss. We present here a novel algorithmic approach that generates highly realistic digital models of human retinal blood vessels, based on established biophysical principles, including fully-connected arterial and venous trees with a single inlet and outlet. This approach, using physics-informed generative adversarial networks (PI-GAN), enables the segmentation and reconstruction of blood vessel networks with no human input and which out-performs human labelling.

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Structural changes to microvascular networks are increasingly highlighted as markers of pathogenesis in a wide range of disease, e.g. Alzheimer's disease, vascular dementia and tumour growth.

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The lethal zoonosis alveolar echinococcosis is caused by tumour-like growth of the metacestode stage of the tapeworm within host organs. We previously demonstrated that metacestode proliferation is exclusively driven by somatic stem cells (germinative cells), which are the only mitotically active parasite cells that give rise to all differentiated cell types. The gene repertoire required for germinative cell maintenance and differentiation has not been characterised so far.

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Article Synopsis
  • * Research using whole-genome sequencing shows that UK populations of S. ratti consist mostly of asexual lineages that are ancient and likely originated from Asia.
  • * The genes linked to the parasite's life cycle are highly diverse, which may help them thrive in varied host environments, suggesting that similar patterns could also be present in human-infecting Strongyloides species and influence control strategies.
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Hundreds of millions of people worldwide are infected with the whipworm Trichuris trichiura. Novel treatments are urgently needed as current drugs, such as albendazole, have relatively low efficacy. We have investigated whether drugs approved for other human diseases could be repurposed as novel anti-whipworm drugs.

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Vascularization is driven by morphogen signals and mechanical cues that coordinately regulate cellular force generation, migration, and shape change to sculpt the developing vascular network. However, it remains unclear whether developing vasculature actively regulates its own mechanical properties to achieve effective vascularization. We engineered tissue constructs containing endothelial cells and fibroblasts to investigate the mechanics of vascularization.

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The National Collection of Type Cultures (NCTC) was founded on 1 January 1920 in order to fulfil a recognized need for a centralized repository for bacterial and fungal strains within the UK. It is among the longest-established collections of its kind anywhere in the world and today holds approximately 6000 type and reference bacterial strains - many of medical, scientific and veterinary importance - available to academic, health, food and veterinary institutions worldwide. Recently, a collaboration between NCTC, Pacific Biosciences and the Wellcome Sanger Institute established the NCTC3000 project to long-read sequence and assemble the genomes of up to 3000 NCTC strains.

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Episcopic imaging using techniques such as High Resolution Episcopic Microscopy (HREM) and its variants, allows biological samples to be visualized in three dimensions over a large field of view. Quantitative analysis of episcopic image data is undertaken using a range of methods. In this systematic review, we look at trends in quantitative analysis of episcopic images and discuss avenues for further research.

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  • Parasitic helminths, like other pathogens, can quickly develop resistance to drugs, making it crucial to understand the genetics behind this resistance, especially in nematodes.
  • This study used genetic crosses in natural hosts to map resistance genes for major classes of anthelmintics, identifying new alleles linked to resistance against benzimidazoles, levamisole, and ivermectin.
  • The findings pinpoint the gene cky-1 as significant for ivermectin survival, providing a pathway for developing molecular diagnostics to address drug resistance in parasitic infections.
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  • In schistosomiasis control areas in Africa, regular mass drug administration (MDA) with praziquantel (PZQ) is crucial for disease management, but the genetic impact of this treatment on schistosomes is not well understood.
  • A study collected whole-genome sequence data from 174 miracidia in Uganda, revealing that the parasite populations in fishing communities have greater genetic diversity than those in nearby villages, with variations observed before and after PZQ treatment.
  • The research indicated that post-treatment parasite populations show signs of natural selection, potentially leading to reduced susceptibility to PZQ, highlighting concerns about the effectiveness of the drug over time.
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  • Whipworms are parasites that live in the large intestines of humans and other animals, causing sickness.
  • Scientists studied how these larvae enter and infect the intestines using mice and a special lab model.
  • They found that whipworm larvae break down mucus to invade cells and can cause damage, which might trigger the body’s immune response to fight back.
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Advances in biological imaging have accelerated our understanding of human physiology in both health and disease. As these advances have developed, the opportunities gained by integrating with cutting-edge mathematical models have become apparent yet remain challenging. Combined imaging-modelling approaches provide unprecedented opportunity to correlate data on tissue architecture and function, across length and time scales, to better understand the mechanisms that underpin fundamental biology and also to inform clinical decisions.

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  • Schistosomes are the causative agents of schistosomiasis, a major global parasitic disease second only to malaria, with significant health and socio-economic impacts.
  • The study utilizes PacBio long-read sequencing to enhance the genome assembly of Schistosoma bovis, a parent species of hybrid schistosomes found in Europe, revealing a hybrid composition of 77% from the human-infective species S. haematobium and 23% from S. bovis.
  • Findings indicate that traditional egg morphology diagnostic methods are insufficient for identifying hybrids, highlighting the importance of genetic tests for accurate classification.
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Background: The consequences of the earth's daily rotation have led to 24-h biological rhythms in most organisms. Even some parasites are known to have daily rhythms, which, when in synchrony with host rhythms, can optimise their fitness. Understanding these rhythms may enable the development of control strategies that take advantage of rhythmic vulnerabilities.

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Imaging intact human organs from the organ to the cellular scale in three dimensions is a goal of biomedical imaging. To meet this challenge, we developed hierarchical phase-contrast tomography (HiP-CT), an X-ray phase propagation technique using the European Synchrotron Radiation Facility (ESRF)'s Extremely Brilliant Source (EBS). The spatial coherence of the ESRF-EBS combined with our beamline equipment, sample preparation and scanning developments enabled us to perform non-destructive, three-dimensional (3D) scans with hierarchically increasing resolution at any location in whole human organs.

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  • Control of schistosomiasis, a parasitic disease, depends on administering the drug praziquantel, which reduces infection rates but has unclear effects on the parasites' evolution and transmission.
  • A study sequenced genomes of 198 Schistosoma mansoni larvae from Ugandan children, revealing that treatment did not significantly reduce the genetic diversity of parasites in high transmission areas like Lake Victoria.
  • The research indicates positive selection in some genes related to praziquantel's mechanism, but no significant harmful genetic changes were identified, highlighting the need for genomic monitoring as disease elimination efforts continue.
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At least 250 million people worldwide suffer from schistosomiasis, caused by worms. Genome sequences for several species are available, including a high-quality annotated reference for . There is a pressing need to develop a reliable functional toolkit to translate these data into new biological insights and targets for intervention.

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Human organs are complex, three-dimensional and multiscale systems. Spatially mapping the human body down through its hierarchy, from entire organs to their individual functional units and specialised cells, is a major obstacle to fully understanding health and disease. To meet this challenge, we developed hierarchical phase-contrast tomography (HiP-CT), an X-ray phase propagation technique utilising the European Synchrotron Radiation Facility's Extremely Brilliant Source: the world's first high-energy 4 generation X-ray source.

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Extracellular RNAs (ex-RNAs) are secreted by cells through different means that may involve association with proteins, lipoproteins or extracellular vesicles (EV). In the context of parasitism, ex-RNAs represent new and exciting communication intermediaries with promising potential as novel biomarkers. In the last years, it was shown that helminth parasites secrete ex-RNAs, however, most work mainly focused on RNA secretion mediated by EV.

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Background: Guinea worm-Dracunculus medinensis-was historically one of the major parasites of humans and has been known since antiquity. Now, Guinea worm is on the brink of eradication, as efforts to interrupt transmission have reduced the annual burden of disease from millions of infections per year in the 1980s to only 54 human cases reported globally in 2019. Despite the enormous success of eradication efforts to date, one complication has arisen.

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Haemonchus contortus is a globally distributed and economically important gastrointestinal pathogen of small ruminants and has become a key nematode model for studying anthelmintic resistance and other parasite-specific traits among a wider group of parasites including major human pathogens. Here, we report using PacBio long-read and OpGen and 10X Genomics long-molecule methods to generate a highly contiguous 283.4 Mbp chromosome-scale genome assembly including a resolved sex chromosome for the MHco3(ISE).

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Background: Chromosome-level assemblies are indispensable for accurate gene prediction, synteny assessment, and understanding higher-order genome architecture. Reference and draft genomes of key helminth species have been published, but little is yet known about the biology of their chromosomes. Here, we present the complete genome of the tapeworm Hymenolepis microstoma, providing a reference quality, end-to-end assembly that represents the first fully assembled genome of a spiralian/lophotrochozoan, revealing new insights into chromosome evolution.

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Lymphatic filariasis affects ∼120 million people and can result in elephantiasis and hydrocele. Here, we report the nearly complete genome sequence of the best-studied causative agent of lymphatic filariasis, The assembly contains four autosomes, an X chromosome, and only eight gaps but lacks a contiguous sequence for the known Y chromosome.

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Schistosomes are parasitic blood flukes that survive for many years within the mammalian host vasculature. How the parasites establish a chronic infection in the hostile bloodstream environment, whilst evading the host immune response is poorly understood. The parasite develops morphologically and grows as it migrates to its preferred vascular niche, avoiding or repairing damage from the host immune system.

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