Biology subjects

Hubbard, A.

Publications and source records attributed to Hubbard, A..

16 recordsLinked to original sources

bioRxiv2026

LEMONmethyl-seq: Targeted long-read DNA methylation profiling reveals dynamics of CRISPR epigenome editing and endogenous DNA methylation patterns

BACKGROUNDDNA methylation is the most prevalent epigenetic modification in human cells and undergoes dynamic changes during cell differentiation, disease progression, and aging. Here, we introduce Locus-Enriched Mapping Of Nucleotide methylation (LEMONmethyl-seq): an optimized, cost-effective pipeline for single-nucleotide detection of DNA methylation using locus-specific amplification and long-read DNA sequencing. RESULTSWe apply LEMONmethyl-seq to profile DNA methylation of endogenous gene promoters across different cell types along with DNA methylation establishment and long-range propagation induced by CRISPR epigenome editing technologies. We profile dynamic changes in DNA methylation patterns on transposable element genomic loci during global epigenetic resetting in stem cells, and we identify site-specific enrichment of non-canonical CpH methylation on genomic sites in stem cells and cultured neurons. Lastly, we apply LEMONmethyl-seq to profile DNA methylation across the MGMT promoter, a clinical biomarker for glioblastoma. We identify additional differentially methylated sites correlated with chemotherapeutic sensitivity, which may be clinically relevant. CONCLUSIONSTogether, LEMONmethyl-seq serves as a cost-effective, long-read DNA methylation sequencing pipeline that advances methods for detecting DNA methylation patterns and dynamics in mammalian cells. We envision its broad use for studying chromatin pathways, diagnostics, and therapeutic applications.

molecular biology↗

bioRxiv2025

The Portable Microhaplotype Object and Tools

Structured AbstractO_ST_ABSMotivationC_ST_ABSThe rapid increase in the generation of targeted sequencing data offers immense potential for research, medicine, and public health, however the lack of an established standard for these data has led to disparate solutions for data storage. A widely accepted standard is essential for data sharing, reuse, and the coordinated development of interoperable analysis tools. ResultsWe propose the Portable Microhaplotype Object (PMO), a standardized format for efficiently and losslessly storing phased targeted sequencing data (microhaplotypes). The PMO format is JSON-based, allowing efficient, relational storage of genetic data together with relevant metadata to minimize orphaned data. The format includes required fields and a curated set of optional fields leveraging established ontologies. To facilitate ease of use, we developed pmotools-python, an open-source package for creating, manipulating, and exporting PMO data into common formats. Additionally, we provide a simple web-based app to quickly create PMO files from tabular inputs, making the format accessible to a wide variety of users. Example datasets from Plasmodium, Anopheles, Escherichia coli, and Staphylococcus aureus demonstrate the broad applicability of the approach. PMO will streamline data sharing, foster interoperability, and accelerate the development of harmonized analysis tools. Availability and implementationThe Portable Microhaplotype Object (PMO) project, including the ontology specification, software tools, example datasets, and tutorials, is freely available athttps://plasmogenepi.github.io/PMO_Docs/. Key software components and datasets have archived releases with DOIs to ensure permanence, detailed in the Supplementary Text 1-5. Contactkathrynmmurie@gmail.com or nickjhathaway@gmail.com

bioinformatics↗

bioRxiv2025

Hyperspectral image analysis for classification of multiple infections in wheat

Plant diseases can cause heavy yield losses in arable crops resulting in major economic losses. Effective early disease recognition is paramount for modern large-scale farming. Since plants can be infected with multiple concurrent pathogens, it is important to be able to distinguish and identify each disease to ensure appropriate treatments can be applied. Hyperspectral imaging is a state-of-the art computer vision approach, which can improve plant disease classification, by capturing a wide range of wavelengths before symptoms become visible to the naked eye. Whilst a lot of work has been done applying the technique to identifying single infections, to our knowledge, it has not been used to analyse multiple concurrent infections which presents both practical and scientific challenges. In this study, we investigated three wheat pathogens (yellow rust, mildew and Septoria), cultivating co-occurring infections, resulting in a dataset of 1,447 hyperspectral images of single and double infections on wheat leaves. We used this dataset to train four disease classification algorithms (based on four neural network architectures: Inception and EfficientNet with either a 2D or 3D convolutional layer input). The highest accuracy was achieved by EfficientNet with a 2D convolution input with 81% overall classification accuracy, including a 72% accuracy for detecting a combined infection of yellow rust and mildew. Moreover, we found that hyperspectral signatures of a pathogen depended on whether another pathogen was present, raising interesting questions about co-existence of several pathogens on one plant host. Our work demonstrates that the application of hyperspectral imaging and deep learning is promising for classification of multiple infections in wheat, even with a relatively small training dataset, and opens opportunities for further research in this area. However, the limited number of Septoria and yellow rust + Septoria samples highlights the need for larger, more balanced datasets in future studies to further validate and extend our findings under field conditions.

pathology↗

bioRxiv2024

Population genomics and molecular epidemiology of wheat powdery mildew in Europe

Agricultural diseases are a major threat to sustainable food production. Yet, for many pathogens we know exceptionally little about their epidemiological and population dynamics, and this knowledge gap is slowing the development of efficient control strategies. Here we study the population genomics and molecular epidemiology of wheat powdery mildew, a disease caused by the biotrophic fungus Blumeria graminis forma specialis tritici (Bgt). We sampled Bgt for two consecutive years, 2022 and 2023, from 22 countries in Europe and surrounding regions, and compiled a genomic dataset of 415 Bgt isolates. We found one single epidemic unit in the north of Europe, consisting of a highly homogeneous population. Conversely, the south of Europe hosts smaller local populations which are less interconnected. In addition, we show that the population structure can be largely predicted by the prevalent wind patterns. We identified several loci that were under selection in the recent past, including fungicide targets and avirulence genes. Some of these loci are common between populations, while others are not, suggesting different local selective pressures. We reconstructed the evolutionary history of one of these loci, AvrPm17, coding for an effector recognized by the wheat receptor Pm17. We found evidence for a soft sweep on standing genetic variation. Multiple AvrPm17 haplotypes, which can partially escape recognition by Pm17, spread rapidly throughout the continent upon its introduction in the early 2000s. We also identified a new virulent variant, which emerged more recently and can evade Pm17 resistance altogether. Overall, we highlight the potential of genomic surveillance in resolving the evolutionary and epidemiological dynamics of agricultural pathogens, as well as in guiding control strategies.

evolutionary biology↗

bioRxiv2024

Discovery of functional NLRs using expression level, high-throughput transformation, and large-scale phenotyping

Protecting crops from pests and diseases is vital for the sustainable agricultural systems needed for food security. Introducing functional resistance genes to enhance the plant immune system is an effective method of disease control, but identifying new immune receptors is time-consuming and resource intensive. We observed that functional immune receptors of the NLR class show a signature of high expression in uninfected plants across both monocot and dicot species. Here we show that this signature, combined with high throughput crop transformation, can be used to rapidly identify candidate NLRs from diverse plant species and validate pathogen resistance directly in crop plants. As a proof of concept, we generated a wheat transgenic library carrying 995 NLRs from 18 grass species. Screening the collection with the stem rust pathogen Puccinia graminis, which is a major threat to wheat production, we confirm 19 new resistance genes. This pipeline facilitates resistance gene discovery, unlocking a large gene pool of diverse and non-domesticated plant species and providing in-planta gene validation of disease resistance directly in crops.

plant biology↗

bioRxiv2024

Structural basis for catalysis and selectivity of phospholipid synthesis by eukaryotic choline-phosphotransferase

Phospholipids are the most abundant component in lipid membranes and are essential for the structural and functional integrity of the cell. In eukaryotic cells, phospholipids are primarily synthesized de novo through the Kennedy pathway that involves multiple enzymatic processes. The terminal reaction is mediated by a group of cytidine-5-diphosphate (CDP)-choline /CDP-ethanolamine-phosphotransferases (CPT/EPT) that use 1,2-diacylglycerol (DAG) and CDP-choline or CDP-ethanolamine to produce phosphatidylcholine (PC) or phosphatidylethanolamine (PE) those are the main phospholipids in eukaryotic cells. Here we present the structure of the yeast CPT1 in multiple substrate-bound states. Structural and functional analysis of these binding-sites reveal the critical residues for the DAG acyl-chain preference and the choline/ethanolamine selectivity. Additionally, we present the structure in complex with a potent inhibitor characterized in this study. The ensemble of structures allows us to propose the reaction mechanism for phospholipid biosynthesis by the family of CDP-alcohol phosphatidyltransferases (CDP-APs).

biochemistry↗

bioRxiv2021

A lineage-specific Exo70 is required for receptor kinase-mediated immunity in barley

In the evolution of land plants, the plant immune system has experienced expansion in immune receptor and signaling pathways. Lineage-specific expansions have been observed in diverse gene families that are potentially involved in immunity, but lack causal association. Here, we show that Rps8-mediated resistance in barley to the fungal pathogen Puccinia striiformis f. sp. tritici (wheat stripe rust) is conferred by a genetic module: LRR-RK and Exo70FX12, which are together necessary and sufficient. The Rps8 LRR-RK is the ortholog of rice extracellular immune receptor Xa21 and Exo70FX12 is a member of the Poales-specific Exo70FX clade. The Exo70FX clade emerged after the divergence of the Bromeliaceae and Poaceae, and comprises from 2 to 75 members in sequenced grasses. These results demonstrate the requirement of a lineage-specific Exo70FX12 in Rps8 LRR-RK immunity and suggest that the Exo70FX clade may have evolved a specialized role in receptor kinase signaling.

plant biology↗

bioRxiv2020

Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial

Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and abundance of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing STH eggs in soil from household courtyards. We collected soil samples from 1405 households enrolled in the sanitation intervention (n=419) and control (n=914) groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed samples for Ascaris lumbricoides, Trichuris trichiura, and hookworm eggs by microscopy. We estimated prevalence ratios (PR) and relative egg count reductions (ECR) to compare the prevalence of any STH eggs and arithmetic and geometric mean egg counts for any STH per gram of soil between the sanitation and control arms. Among intervention households, latrines achieved high and sustained user uptake by adults while child open defecation remained common and most households did not dispose of child feces hygienically. In courtyard soil from control households, the prevalence of any STH eggs was 75.7% and the prevalence of any larvated STH eggs was 67.3%. A. lumbricoides was detected in 63.0% of control samples and T. trichiura in 55.7% of control samples; hookworm was not detected in any sample. The arithmetic mean egg count for any STH was 3.96 eggs/dry gram, while the geometric mean was 1.58 eggs/dry gram. There was no difference between the intervention and control groups in the prevalence of any STH eggs (PR=0.98 (95% CI: 0.91-1.05)) or mean egg counts (ECR=0.08 (95% CI: -0.10, 0.26) for geometric mean and 0.07 (95% CI: -0.22, 0.37) for arithmetic mean). Adjusted models gave similar results. A compound-level sanitation intervention that provided improved latrines and tools for disposal of child and animal feces did not have an impact on environmental reservoirs of STH eggs. In order to effectively reduce the prevalence and abundance of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces. Author summaryImproved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and abundance of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing STH eggs in soil from household courtyards. We collected soil samples from 1405 households enrolled in the control and sanitation groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed samples for Ascaris lumbricoides, Trichuris trichiura and hookworm eggs by microscopy. We found no effect of the sanitation intervention on STH eggs in soil. In order to effectively reduce the prevalence and abundance of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces.

ecology↗

bioRxiv2020

Piperacillin/tazobactam resistant, cephalosporin susceptible Escherichia coli bloodstream infections driven by multiple resistance mechanisms across diverse sequence types

Resistance to piperacillin/tazobactam (TZP) in Escherichia coli has predominantly been associated with mechanisms that confer resistance to third generation cephalosporins. Recent reports have identified E. coli strains with phenotypic resistance to piperacillin/tazobactam but susceptibility to third generation cephalosporins (TZP-R/3GC-S). In this study we sought to determine the genetic diversity of this phenotype in E. coli (n = 58) isolated between 2014-2017 at a single tertiary hospital in Liverpool, UK, as well as the associated resistance mechanisms. We compare our findings to a UK-wide collection of invasive E. coli isolates (n = 1509) with publicly available phenotypic and genotypic data. These data sets included the TZP-R/3GC-S phenotype (n = 68), a piperacillin/tazobactam and third generation cephalosporin-susceptible (TZP-S/3GC-S, n = 1271) phenotypes. The TZP-R/3GC-S phenotype was displayed in a broad range of sequence types which was mirrored in the same phenotype from the UK-wide collection, and the overall diversity of invasive E. coli isolates. The TZP-R/3GC-S isolates contained a diverse range of plasmids, indicating multiple acquisition events of TZP resistance mechanisms rather than clonal expansion of a particular plasmid or sequence type. The putative resistance mechanisms were equally diverse, including hyperproduction of TEM-1, either via strong promoters or gene amplification, carriage of inhibitor resistant {beta}-lactamases, and an S133G b/aCTX-M-15 mutation detected for the first time in clinical isolates. Several of these mechanisms were present at a lower abundance in the TZP-S/3GC-S isolates from the UK-wide collection, but without the associated phenotypic resistance to TZP. Our findings highlight the complexity of this cryptic phenotype and the need for continued phenotypic monitoring, as well as further investigation to improve detection and prediction of the TZP-R/3GC-S phenotype from genomic data.

microbiology↗

bioRxiv2020

PolyA-modulating antisense oligonucleotides reveal opposing functions for long non-coding RNA NEAT1 isoforms in neuroblastoma

Many long non-coding RNAs (lncRNA) are highly dysregulated in cancer and are emerging as therapeutic targets. One example is NEAT1, which consists of two overlapping lncRNA isoforms, NEAT1_1 (3.7kb) and NEAT1_2 (23kb), that are functionally distinct. The longer NEAT1_2 is responsible for scaffolding gene-regulatory nuclear bodies termed paraspeckles, whereas NEAT1_1 is involved in paraspeckle-independent function. The NEAT1 isoform ratio is dependent on the efficient cleavage and polyadenylation of NEAT1_1 at the expense of NEAT1_2. Here we developed a targeted antisense oligonucleotide (ASO) approach to sterically block NEAT1_1 polyadenylation processing, achieving upregulation of NEAT1_2 and abundant paraspeckles. We have applied these ASOs to cells of the heterogeneous infant cancer, neuroblastoma, as we found higher NEAT1_1:NEAT1_2 ratio and lack of paraspeckles in high-risk neuroblastoma cells. These ASOs decrease NEAT1_1 levels, increase NEAT1_2/paraspeckles and concomitantly reduce cell viability in high-risk neuroblastoma specifically. In contrast, overexpression of NEAT1_1 has the opposite effect, increasing cell-proliferation. Transcriptomic analyses of high-risk neuroblastoma cells with altered NEAT1 ratios and increased paraspeckle abundance after ASO treatment showed an upregulation of differentiation pathways, as opposed to the usual aggressive neuroblastic phenotype. Thus, we have developed potential anti-cancer ASO drugs that can transiently increase growth-inhibiting NEAT1_2 RNA at the expense of growth-promoting NEAT1_1 RNA. These ASOs, unlike others that degrade lncRNAs, provide insights into the importance of altering lncRNA polyadenylation events to suppress tumorigenesis as a strategy to combat cancer.

cancer biology↗

bioRxiv2019

Isolation of an antimicrobial resistant, biofilm forming, Klebsiella grimontii isolate from a re-usable water bottle.

A re-usable water bottle was swabbed as part of the citizen science project Swab and Send and a Klebsiella grimontii isolate was recovered on chromogenic agar and designated SS141. Whole genome sequencing of SS141 showed it has the potential to be a human pathogen as it contains the biosynthetic gene cluster for the potent cytotoxin, kleboxymycin, and genes for other virulence factors. The genome also contains blaOXY-6-4 and fosA which is likely to explain the observed resistance to ampicillin, amoxicillin and fosfomycin. We have also shown that SS141 is a potent biofilm former, providing a reasonable explanation for its ability to colonise a re-usable water bottle. With the increasing use of re-usable water bottles as an alternative to disposables, and a strong forecast for growth in this industry over the next decade, this study highlights the need for cleanliness comparable to other re-usable culinary items.

microbiology↗

bioRxiv2019

Illuminating the functional rare biosphere of the Greenland Ice Sheet’s Dark Zone

The Dark Zone of the western Greenland Ice Sheet is the most expansive region of contiguous bare terrestrial ice in the Northern Hemisphere. Microbial processes within the Dark Zone play an important role in driving extensive albedo reduction and amplified melting, yet the composition and function of those consortia have not been fully identified. Here we present the first results from joint 16S rRNA gene and 16S rRNA (cDNA) analysis for the comparison of input (snow), storage (cryoconite), and output (supraglacial stream water) habitats across the Dark Zone over the melt season. Our analysis reveals that all three Dark Zone communities are characterized by a preponderance of rare taxa exhibiting high protein synthesis potential (PSP). Furthermore, taxa with high PSP represent highly connected \"bottlenecks\" within community structure, consistent with roles as metabolic hubs within their communities. Finally, the detection of low abundance-high PSP taxa affiliated with Methylobacterium within snow and stream water indicates a potential role for Methylobacterium in the carbon cycle of Greenlandic snowpacks, and importantly, the export of potentially active methylotrophs to the bed of the Greenland Ice Sheet. By comparing the dynamics of bulk and potentially active microbial communities in the Dark Zone of the Greenland Ice Sheet our study provides insight into the mechanisms and impacts of the microbial colonization of this critical region of our melting planet.

microbiology↗

bioRxiv2019

Comparison of long-read sequencing technologies in the hybrid assembly of complex bacterial genomes

Illumina sequencing allows rapid, cheap and accurate whole genome bacterial analyses, but short reads (<300 bp) do not usually enable complete genome assembly. Long read sequencing greatly assists with resolving complex bacterial genomes, particularly when combined with short-read Illumina data (hybrid assembly). However, it is not clear how different long-read sequencing methods impact on assembly accuracy. Relative automation of the assembly process is also crucial to facilitating high-throughput complete bacterial genome reconstruction, avoiding multiple bespoke filtering and data manipulation steps. In this study, we compared hybrid assemblies for 20 bacterial isolates, including two reference strains, using Illumina sequencing and long reads from either Oxford Nanopore Technologies (ONT) or from SMRT Pacific Biosciences (PacBio) sequencing platforms. We chose isolates from the Enterobacteriaceae family, as these frequently have highly plastic, repetitive genetic structures and complete genome reconstruction for these species is relevant for a precise understanding of the epidemiology of antimicrobial resistance. We de novo assembled genomes using the hybrid assembler Unicycler and compared different read processing strategies. Both strategies facilitate high-quality genome reconstruction. Combining ONT and Illumina reads fully resolved most genomes without additional manual steps, and at a lower consumables cost per isolate in our setting. Automated hybrid assembly is a powerful tool for complete and accurate bacterial genome assembly. IMPACT STATEMENTIllumina short-read sequencing is frequently used for tasks in bacterial genomics, such as assessing which species are present within samples, checking if specific genes of interest are present within individual isolates, and reconstructing the evolutionary relationships between strains. However, while short-read sequencing can reveal significant detail about the genomic content of bacterial isolates, it is often insufficient for assessing genomic structure: how different genes are arranged within genomes, and particularly which genes are on plasmids - potentially highly mobile components of the genome frequently carrying antimicrobial resistance elements. This is because Illumina short reads are typically too short to span repetitive structures in the genome, making it impossible to accurately reconstruct these repetitive regions. One solution is to complement Illumina short reads with long reads generated with SMRT Pacific Biosciences (PacBio) or Oxford Nanopore Technologies (ONT) sequencing platforms. Using this approach, called hybrid assembly, we show that we can automatically fully reconstruct complex bacterial genomes of Enterobacteriaceae isolates in the majority of cases (best-performing method: 17/20 isolates). In particular, by comparing different methods we find that using the assembler Unicycler with Illumina and ONT reads represents a low-cost, high-quality approach for reconstructing bacterial genomes using publicly available software. DATA SUMMARYRaw sequencing data and assemblies have been deposited in NCBI under BioProject Accession PRJNA422511 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA422511). We confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.

bioinformatics↗

bioRxiv2018

Interaction of modified oligonucleotides with nuclear proteins, formation of novel nuclear structures and sequence-independent effects on RNA processing

Oligonucleotides and nucleic acid analogues that alter gene expression are showing therapeutic promise for selected human diseases. The modification of synthetic nucleic acids to protect against nuclease degradation and to influence drug function is common practice, however, such modifications may also confer unexpected physicochemical and biological properties. Here we report backbone-specific effects of modified oligonucleotides on subnuclear organelles, altered distribution of nuclear proteins, the appearance of novel structured nuclear inclusions, and modification of RNA processing in cultured cells transfected with antisense oligonucleotides on a phosphorothioate backbone. Phosphodiester and phosphorodiamidate morpholino oligomers elicited no such consequences. Disruption of subnuclear structures and proteins elicit severe phenotypic disturbances, revealed by transcriptomic analysis of fibroblasts exhibiting such disruption. These data suggest that the toxic effects and adverse events reported after clinical evaluation of phosphorothioate nucleic acid drugs may be mediated, at least in part, by non-specific interaction of nuclear components with the phosphorothioate backbone.

molecular biology↗

bioRxiv2018

Identifying Mechanisms of Regulation to Model Carbon Flux During Heat Stress And Generate Testable Hypotheses

Understanding biological response to stimuli requires identifying mechanisms that coordinate changes across pathways. One of the promises of multi-omics studies is achieving this level of insight by simultaneously identifying different levels of regulation. However, computational approaches to integrate multiple types of data are lacking. An effective systems biology approach would be one that uses statistical methods to detect signatures of relevant network motifs and then builds metabolic circuits from these components to model shifting regulatory dynamics. For example, transcriptome and metabolome data complement one another in terms of their ability to describe shifts in physiology. Here, we extend a previously described method used to identify single nucleotide polymorphism (SNPs) associated with metabolic changes (Gieger et al., 2008). We apply this strategy to link changes in sulfur, amino acid and lipid production under heat stress by relating ratios of compounds to potential precursors and regulators. This approach provides integration of multi-omics data to link previously described, discrete units of regulation into functional pathways and hypothesizes novel biology relevant to the heat stress response.

genomics↗

bioRxiv2016

Defining the genetic architecture of stripe rust resistance in the barley accession HOR1428

Puccinia striiformis f. sp. hordei, the causal agent of barley stripe rust, is a destructive fungal pathogen that significantly affects barley cultivation. A major constraint in breeding resistant cultivars is the lack of mapping information of resistance (R) genes and their introgression into adapted germplasm. A considerable number of R genes have been described in barley to P. striiformis f. sp. hordei, but only a few loci have been mapped. Previously, Chen and Line (1999) reported two recessive seedling resistance loci in the Ethiopian landrace HOR 1428. In this study, we map two loci that confer resistance to P. striiformis f. sp. hordei in HOR 1428, which are located on chromosomes 3H and 5H. Both loci act as additive effect QTLs, each explaining approximately 20% of the phenotypic variation. We backcrossed HOR 1428 to the cv. Manchuria and selected based on markers flanking the RpsHOR128-5H locus. Saturation of the RpsHOR1428-5H locus with markers in the region found KASP marker K_1_0292 in complete coupling with resistance to P. striiformis f. sp. hordei and was designated Rps9. Isolation of Rps9 and flanking markers will facilitate the deployment of this genetic resource into existing programs for P. striiformis f. sp. hordei resistance.

plant biology↗