Biology subjects

Holmes, E.

Publications and source records attributed to Holmes, E..

At least 19 recordsLinked to original sources

bioRxiv2026

Activation of basal forebrain cholinergic neurons promotes the attribution of incentive salience to reward cues in male rats

Background: Reward-associated environmental stimuli (cues) can gain incentive salience in some individuals, thereby becoming attractive, reinforcing, and instigators of motivational states. In rodents, the tendency to attribute incentive salience can be measured using a Pavlovian Conditioned Approach (PavCA) procedure, in which approach to a food cue (sign-tracking), relative to approach to the food delivery location (goal-tracking) is the operational definition of the incentive salience attributed to the cue. Growing evidence suggests that acetylcholine promotes this process, thus the current study tested the effect of activating cholinergic neurons in the basal forebrain on sign- and goal-tracking during PavCA. Methods: We injected a Cre-dependent virus with excitatory Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) into the horizontal limb of the diagonal band of Broca of transgenic rats expressing cre-recombinase in acetylcholine containing neurons. We then injected clozapine-n-oxide (CNO) before each of eight sessions of PavCA. On the ninth session, no CNO was given to test if any effects were immediately reversible. Results: We found that activation of basal forebrain cholinergic neurons increased sign-tracking over time without an overall effect on goal-tracking, relative to a control group injected with a control virus. Changes in responding from the final CNO session to the saline test did not differ between virus groups. Conclusions: This effect demonstrates that acetylcholine promotes the attribution of incentive salience to a reward-related cue. Future studies should investigate the effect of inhibiting this area on sign-tracking as well as how activation of this area influences reactivity to cues associated with other rewards such as drugs of abuse.

neuroscience↗

bioRxiv2026

A dependency-free, streamable format and cross-language toolkit for scalable LC-MS feature detection: reading only what you need

Mass spectrometry generates data faster than it can be read, and the exchange standard, mzML, is text-based and must be parsed in full before any spectrum is accessible. Binary alternatives are smaller but depend on storage engines such as HDF5, so access is dictated by the engine, not the file. We present Ionic (.ion), an open-source, compact, streamable binary format, and Quant{middle dot}ion, a processing toolkit built on the former. Ionic stores spectra, chromatograms and metadata as independently compressed, indexed blocks, so a reader retrieves only the bytes it needs, even inside a web browser, and converts losslessly to and from mzML. Ionic was smaller than compressed mzMLb on every acquisition type tested, and extracting one compound took under 40 ms, 35 to 90 times faster than an mzML reader. Quant{middle dot}ion exposes one core to R, Python, and JavaScript with identical results, and recovered 97% of true features on a ground-truth benchmark.

bioinformatics↗

bioRxiv2026

Multi-Omic Dissection of Autism Reveals Dominant Effects of Family, Sex, and Host-Microbe Metabolic Interactions

Autism spectrum disorder (ASD) has been associated with gut microbiome and metabolic alterations, but reported biomarkers are inconsistent and often inadequately account for family and shared environment. We analysed 620 children, including 334 with ASD and 286 neurotypical siblings, with a median age of 6.0 years (IQR 4.0-8.0). Faecal and urine samples were collected monthly up to eight times. After quality control, 869 microbiome, 754 faecal metabolome and 787 urine metabolome samples were analysed using 16S rRNA sequencing, NMR and LC-MS metabolomics. Mixed models accounted for family, repeated sampling and biological sex. Family membership explained 46.1% of variation across microbiome and metabolome profiles, compared with 8.0% attributable to ASD. After family adjustment, ASD explained only 0.1% to 0.3% of microbiome beta diversity. No stable taxonomic biomarkers were identified, and microbial classification was poor (AUROC <0.75). Urinary metabolomics identified elevated 5-hydroxy-L-tryptophan and altered phenylalanine metabolism. Structural equation modelling found no direct associations between selected taxa and metabolites. These findings argue against a universal ASD microbiome and indicate that family context contributes more strongly than diagnosis to microbial and metabolic variation.

microbiology↗

bioRxiv2026

Postprandial profiling of the duodenal microbiome reveals the impact of food structure and association with luminal metabolite and gut hormone responses

The human duodenum harbours a complex, dynamic microbial community that is challenging to study due to inaccessibility, particularly postprandially when nutrient-rich chyme and fluctuating metabolites create unique microbial niches. We used naso-duodenal intubation to longitudinally sample duodenal luminal contents following pea-based meals of differing food structure, alongside parallel blood collection. Shotgun metagenomic sequencing, comprehensive metabolomic profiling and gut hormone measurements were combined to explore microbe-metabolite-hormone interactions. Food structure significantly affected postprandial bacterial composition, with saccharolytic oral taxa increasing after meals with intact structure. Alpha diversity was influenced by structure type (P = 0.025), with whole pea seeds promoting greater diversity than pea flour. Network analysis revealed complex interactions between the duodenal microbiome, luminal metabolites and gut hormones, with most microbial associations linked to glucose-dependent insulinotropic polypeptide (GIP) rather than glucagon-like peptide-1 (GLP-1). Metabolic profiling showed meal-dependent changes in amino acid metabolism, including shifts in D/L amino acid ratios over time consistent with microbial metabolism. The duodenal microbiome showed close phylogenetic relationships with the oral microbiome, with composition influenced by food structuring and swallowing. These findings reveal dynamic microbe-metabolite interplay in the human duodenum during digestion and its relationship to gut hormone responses.

microbiology↗

bioRxiv2026

Reproducible Tools and Enhanced Computational Workflows for Batch Effect Evaluation of High-Throughput Data Using BatchQC

Batch effect correction is a common and often necessary step in data analysis to reduce bias due to technical and experimental factors when combining multiple batches of data. The severity of the batch effects dictates the correction strategy; therefore, a careful assessment of each datasets batch effects is necessary. BatchQC is an R package that provides reproducible tools and visualizations for quantitatively and qualitatively addressing batch effects across a broad range of data types. BatchQC integrates with standardized Bioconductor data structures and features an object-oriented design, enabling the application of workflows that can freely evaluate and process data within and outside the package tools. Common batch evaluation methods, along with novel quantitative metrics, help determine the benefits of batch correction for each dataset and enable direct comparisons between methods. Here, we present BatchQC as the first comprehensive batch-correction R package, with independent tools, reproducible workflows, visualization, and novel statistics.

bioinformatics↗

bioRxiv2026

Heterogeneity in neural network engagement supports individual differences in top-down attention

Top-down attention enables selective prioritisation of goal-relevant information, yet how attentional control varies across individuals remains unclear, particularly in relation to sensory processing. Here, we combined magnetoencephalography (MEG) and pupillometry--in older adults performing a spatial cueing task--to examine both shared and subject-specific aspects of top-down attention. Informative spatial cues elicited sustained activity in fronto-parietal and sensory regions, alpha lateralisation, and increased pupil dilation, replicating established neural and physiological markers. Crucially, these group-level patterns were accompanied by systematic intersubject variability: individuals with greater hearing loss showed increased preparatory engagement of precentral and postcentral gyri, and variation in pupil dilation predicted activity in frontal regions. These results reveal that top-down attention arises from heterogeneous network configurations shaped by sensory processing and strategic resource allocation. Overall, our findings underscore the need to move beyond group averages to capture the neural architecture underlying individual differences in top-down attention.

neuroscience↗

bioRxiv2025

Persistent transcriptomic changes following repeated exposure to wood smoke in non-human primate airway epithelial cells

Exposure to wildfire smoke is a significant public health concern with the respiratory system heavily impacted. Wildfire events are increasing in number and severity, and inhalation of wildfire smoke can lead to airway inflammation, oxidative stress-induced lung injury, impaired mucociliary clearance, and exacerbation of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). Despite these well-documented health risks, the molecular mechanisms underlying the respiratory effects of wildfire smoke exposure and recovery remain incompletely understood. In this study, we utilized transcriptomic and epigenomic analyses to investigate how exposure to wood smoke (WS) influences the expression patterns of gene networks in differentiated tracheobronchial epithelial cells. Our analysis identified exposure-induced differentially methylated regions, differentially expressed genes and gene networks that are implicated in lung disease, including dysregulation of immune responses, oxidative stress and cell death, compromise of epithelial barrier integrity and function, and epigenetic remodeling. Strikingly, significant transcriptomic changes were still detected one week after exposure cessation, enriched in pathways involved in inflammation, wound healing and tissue repair. Despite these transcriptomic and epigenomic perturbations, histology staining revealed no significant changes in epithelial tissue morphology following WS exposure. However, we found a significant number of pulmonary disease-associated genes and pathways whose transcription were affected by WS exposure. Our study enhances understanding of the molecular basis of wildfire smoke-induced respiratory effects and highlights the potential for WS to leave a lasting imprint on airway epithelium, with important implications for respiratory health in exposed populations.

genomics↗

bioRxiv2025

Dried Blood Spot Lipidomics in Diabetes

Comprehensive lipidomic profiling in diabetes has identified disease-associated lipid signatures that may support more personalised monitoring beyond routine glycaemic control. Dried blood spot (DBS) microsampling offers a minimally invasive method for collecting and storing small blood volumes (<50 {micro}L), enabling decentralised and longitudinal sampling. However, its application in lipidomics for cardiometabolic phenotyping remains underexplored. In this study, 34 participants (17 diabetics, 17 non-diabetic controls) self-collected DBS samples using advanced microsampling devices (10 {micro}L, Capitainer(R)B). Lipid extracts were analysed using a validated liquid chromatography-trapped ion mobility-time-of-flight mass spectrometry method optimised for semi-quantitative DBS lipidomics. Multivariate analysis revealed significant differences in lipidomic profiles (n = 432 lipids) between diabetic and non-diabetic individuals (R{superscript 2}Y = 0.82, Q{superscript 2}Y = 0.50, p = 0.05). Key discriminatory lipids (all VIP > 1.44), including HexCer(18:1;O2/24:0), HexCer(18:1;O2/22:0), LPC(16:0), PC(O-34:3), TG(18:0_18:1_20:3), and TG(18:1_18:1_22:6), were consistent with matched venous and capillary plasma samples. Lipid class and structural differences, including elevated long-chain triacylglycerols and reduced lysophosphatidylcholines reflected known dyslipidaemia in diabetes and demonstrate the capacity of DBS to capture biologically meaningful lipid perturbations. Participant-reported outcomes from Problem Areas In Diabetes (PAID-20), Patient Activation Measure (PAM-13), and microsampling perception questionnaires highlighted psychosocial and behavioural insights, and indicated strong support for DBS sampling over venepuncture, citing ease of use and reduced burden. These findings establish DBS lipidomics as a feasible and informative approach for stratifying cardiometabolic disease, supporting broader implementation in remote, personalised monitoring frameworks (Figure 1). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/656742v1_fig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@c53b4org.highwire.dtl.DTLVardef@14b507forg.highwire.dtl.DTLVardef@191e563org.highwire.dtl.DTLVardef@16af172_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Graphical abstract - Chapter 5. C_FIG

biochemistry↗

bioRxiv2024

TiFM2.0 - Versatile mechanical measurement and actuation in live embryos

During development, spatial-temporally patterned tissue-level stresses and mechanical properties create diverse tissue shapes. To understand the mechanics of small-scale embryonic tissues, precisely controlled sensors and actuators are needed. Previously, we reported a control-based approach named tissue force microscopy (TiFM1.0), which combines dynamic positioning and imaging of an inserted cantilever probe to directly measure and impose forces in early avian embryos. Here we present an upgraded system (TiFM2.0) that utilises interferometer positioning to minimise probe holder footprint, enhancing accessibility and imaging signal. This new design enables a double-probe configuration for bidirectional stretching, compression and stress propagation experiments. As proof-of-concept, we showcase a variety of examples of TiFM2.0 applications in chicken and zebrafish embryos, including the characterization of mechanical heterogeneities important for the morphogenesis of the chicken posterior body axis. We also present simplified designs and protocols for the replication of TiFM systems with minimal custom engineering for developmental biology labs.

developmental biology↗

bioRxiv2024

Predicting speech-in-noise ability with static and dynamic auditory figure-ground analysis using structural equation modelling

Auditory figure-ground paradigms assess the ability to extract a foreground figure from a random background, a crucial part of central hearing. Previous studies have shown that the ability to extract static figures (with fixed frequencies) predicts real-life listening: speech-in-noise ability. In this study we assessed both fixed and dynamic figures: the latter comprised component frequencies that vary over time like natural speech. 159 participants (aged 18-79) with a range of peripheral hearing sensitivity were studied. We used hierarchal linear regression and structural equation modelling to examine how well speech-in-noise ability (for words and sentences) could be predicted by age, peripheral hearing, and static and dynamic figure-ground. Regression demonstrated that in addition to the audiogram and age, the low-frequency dynamic figure-ground accounted for significant variance of speech-in-noise, higher than the static figure-ground. The structural models showed that a combination of all types of figure-ground tasks predicted speech-in-noise with a higher effect size than the audiogram or age. Age influenced word perception in noise directly but sentence perception indirectly via effects on peripheral and central hearing. Overall, this study demonstrates that dynamic figure-ground explains more variance of real-life listening than static figure-ground, and the combination of both predicts real-life listening better than hearing sensitivity or age.

neuroscience↗

bioRxiv2024

British Version of the Iowa Test of Consonant Perception

The Iowa Test of Consonant Perception (ITCP) is a single-word closed-set speech- in-noise test with well-balanced phonetic features that provides a reliable testing option for real-world listening. Objectives. The current study aimed to establish a UK version of the test (B-ITCP) based on the British received pronunciation. Design. We conducted a validity test with 46 participants using the B-ITCP test, a sentence-in- noise test, and audiogram. Results. The B-ITCP demonstrated excellent test-retest reliability, cross-talker validity, and good convergent validity, consistent with the US results. Conclusions. These findings suggest that B-ITCP is a reliable measure of speech-in-noise perception, to facilitate comparative or combined studies in USA and UK. All materials (application and scripts) to run or construct the B-ITCP and ITCP are freely available online.

neuroscience↗

bioRxiv2024

Spatial selective auditory attention is preserved in older age but is degraded by peripheral hearing loss

Interest in how ageing affects attention is long-standing, although interactions between sensory and attentional processing in older age have not been systematically studied. Here, we examined interactions between peripheral hearing and selective attention in a spatialised cocktail party listening paradigm, in which three talkers spoke different sentences simultaneously and participants were asked to report the sentence spoken by a talker at a particular location. By comparing a sample of older (N = 61; age = 55- 80 years) and younger (N = 58; age = 18-35 years) adults, we show that, as a group, older adults benefit as much as younger adults from preparatory spatial attention. Although, for older adults, this benefit significantly reduces with greater age-related hearing loss. These results demonstrate that older adults without hearing loss retain the ability to direct spatial selective attention, but this ability deteriorates with age-related hearing loss. Thus, reductions in spatial selective attention likely contribute to difficulties communicating in social settings for older adults with age-related hearing loss. Overall, these findings demonstrate a relationship between mild perceptual decline and attention in older age.

neuroscience↗

bioRxiv2024

Contrasting dynamics of two incursions of low pathogenicity avian influenza virus into Australia

The current panzootic of high pathogenicity avian influenza virus H5N1 demonstrates how viral incursions can have major ramifications for wildlife and domestic animals. Herein, we describe the recent incursion into Australia of two low pathogenicity avian influenza virus subtypes, H4 and H10, that exhibited contrasting evolutionary dynamics. Viruses detected from national surveillance and disease investigations between 2020-2022 revealed 27 genomes, 24 of which have at least one segment more closely related to Eurasian or North American avian influenza lineages than those already circulating in Australia. Phylogenetic analysis revealed that H4 viruses circulating in shorebirds represent a recent incursion from Asia that is distinct from those circulating concurrently in Australian waterfowl. Analysis of the internal segments further demonstrates exclusive, persistent circulation in shorebirds. This contrasts with H10, where a novel lineage has emerged in wild waterfowl, poultry and captive birds across Australia, and has likely replaced previously circulating H10 lineages through competitive exclusion. Elucidating different dynamics for avian influenza incursions supports effective disease risk identification and communication that better informs disease preparedness and response.

microbiology↗

bioRxiv2023

Connecting Thiamine Availability to the Microbial Community Composition in Chinook Salmon Spawning Habitats of the Sacramento River Basin

Thiamine Deficiency Complex (TDC) is a major emerging threat to global populations of culturally and economically important populations of salmonids. Salmonid eggs and embryos can assimilate exogenous thiamine, and evidence suggests that microbial communities in benthic environments can produce substantial amounts of thiamine. We therefore hypothesize that microbially produced thiamine in both riverine surface water and hyporheic zones could serve to rescue early life stages of salmonids suffering from TDC. The distributions of thiamine and its metabolically related compounds (dTRCs) have never been determined in freshwater systems. Similarly, the microbial cycling of these compounds has never been investigated. Here we determine that all dTRCs are present in femto-picomolar concentrations across diverse salmon spawning habitats in Californias Sacramento River system. We observed that thiamine concentrations in the Sacramento River are orders of magnitude lower than marine environments, indicating substantial differences in thiamine cycling between these two environments. Our data suggest that the hyporheic zone is likely the source of thiamine to the overlying surface water. Temporal variations in dTRC concentration were observed where highest concentrations were seen when Chinook salmon were actively spawning. Significant correlations were identified between the richness of differentially abundant ASVs and dTRC concentrations. The influence of these ASVs on dTRC concentrations provide evidence of dTRC cycling by microbes in the hyporheic zone, which would influence the conditions where embryonic salmon incubate. Together, these results indicate a connection between microbial communities in freshwater habitats and the availability of thiamine to spawning TDC-impacted California Central Valley Chinook salmon.

microbiology↗

bioRxiv2023

Clinical prediction of wound re-epithelisation outcomes in non-severe burn injury using the plasma lipidome

Whilst wound repair in severe burns has received substantial research attention, non-severe burns (<20% total body surface area) remain relatively understudied, despite causing considerable physiological impact and constituting most of the hospital admissions for burns. Early prediction of healing outcomes would decrease financial and patient burden, and aid in preventing long-term complications from poor wound healing. Lipids have been implicated in inflammation and tissue repair and may play essential roles in burn wound healing. In this study, plasma samples were collected from 20 non-severe burn patients over 6 weeks from admission, including surgery, and analysed by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy to detect 850 lipids and 112 lipoproteins. Orthogonal projections to latent structures-discriminant analysis was performed to identify changes associated with re-epithelialisation and delayed re-epithelisation. We demonstrated that the lipid and lipoprotein profiles at admission could predict re-epithelisation outcomes at 2 weeks post-surgery, and that these discriminatory profiles were maintained up to 6 weeks post-burn. Inflammatory markers GlycB and C-reactive protein indicated divergent systemic responses to the burn injury at admission. Triacylglycerols, diacylglycerols and low-density lipoprotein subfractions were associated with delayed wound closure (p-value <0.02, Cliffs delta >0.7), whilst high-density lipoprotein subfractions, phosphatidylinositols, phosphatidylcholines, and phosphatidylserines were associated with re-epithelisation at 2 weeks post-surgery (p-value <0.01, Cliffs delta <-0.7). Further model validation will potentially lead to personalised intervention strategies to reduce the risk of chronic complications post-burn injury.

systems biology↗

bioRxiv2023

Gene regulatory network analysis predicts cooperating transcription factor regulons required for FLT3-ITD+ AML growth

AML is a heterogenous disease caused by different mutations. We have previously shown that each mutational sub-type develops its specific gene regulatory network (GRN) with transcription factors interacting with multiple gene modules, many of which are transcription factor genes themselves. Here we hypothesized that highly connected nodes within such networks comprise crucial regulators of AML maintenance. We tested this hypothesis using FLT3-ITD mutated AML as a model and conducted an shRNA drop-out screen informed by this analysis. We show that AML-specific GRNs predict identifying crucial regulatory modules required for AML but not normal cellular growth. Furthermore, our work shows that all modules are highly connected and regulate each other. The careful multi-omic analysis of the role of one (RUNX1) module by shRNA and chemical inhibition shows that this transcription factor and its target genes stabilize the GRN of FLT3-ITD AML and that its removal leads to GRN collapse and cell death.

cancer biology↗

bioRxiv2023

Metabolic consequences of non-severe burn injury are associated with increased plasma markers of inflammation and cardiovascular disease risk.

Globally, burns are a significant cause of injury that can cause substantial acute trauma as well as lead to increased incidence of chronic co-morbidity and disease. To date, research has primarily focused on the systemic response to severe injury, with little in the literature reported on impact of non-severe injuries (<15% total burn surface area; TBSA). To elucidate the metabolic consequences of non-severe burn injury, longitudinal plasma was collected from adults (n=35) who presented at hospital with a non-severe burn injury at admission, and at 6 week follow up. A cross-sectional baseline sample was also collected from non-burn control participants (n=14). Samples underwent multiplatform metabolic phenotyping using 1H nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry to quantify 112 lipoprotein and glycoproteins signatures and 852 lipid species from across 20 subclasses. Multivariate data modelling (Orthogonal projection to latent structures-discriminate analysis) revealed alterations in lipoprotein and lipid metabolism when comparing baseline control to hospital admission samples, with the phenotypic signature found to be sustained at follow up. Univariate (Mann-Whitney U) testing and OPLS-DA indicated specific increases in GlycB (p-value <1.0e-4), low density lipoprotein-2 subfractions (Variable importance in projection score; VIP >6.83e-1) and monoacyglyceride (20:4)(p-value <1.0e-4) and decreases in circulating anti-inflammatory high-density lipoprotein-4 subfractions (VIP >7.75e-1), phosphatidylcholines, phosphatidylglycerols, phosphatidylinositols and phosphatidylserines. The results indicate a persistent systemic metabolic phenotype that occurs even in cases of non-severe burn injury. The phenotype is indicative of an acute inflammatory profile which continues to be sustained post-injury, suggesting an impact on systems health beyond the site of injury. The phenotypes contained metabolic signatures consistent with chronic inflammatory states reported to have elevated incidence post-burn injury. Such phenotypic signatures may provide patient stratification opportunities, to identify individual responses to injury, personalise intervention strategies and improve acute care, reducing risk of chronic co-morbidity.

systems biology↗

bioRxiv2023

Temporal dynamics of trauma memory persistence

Traumatic events lead to distressing memories, but such memories are made all the worse when they intrude to mind unbidden and recurrently. Intrusive memories are a hallmark of several mental health disorders including posttraumatic stress disorder (PTSD) and can persist for years. Critically, the reduction of intrusive memories provides a treatment target. While cognitive models for psychological trauma exist, these lack formal quantitative structure and robust empirical validation. Here we develop a mechanistically-driven, quantitative framework to extend understanding of the temporal dynamic processes of trauma memory. We show how the marginal gains of interventions for intrusive memories can be enhanced as key properties of the intervention vary. Validating the framework against empirical data highlights that while emerging interventions to reduce occurrence of intrusive memories can be effective, counter-intuitively, maintaining these memories in a sufficiently reactivated state is essential for preventing their persistence. Author SummaryIntrusive memories and flashbacks after trauma are prominent in several mental disorders. Quantifying these intrusions is the aim of the current study. While many conceptual models for trauma memory exist, none provide a mechanistic framework for validating experimental or clinical evidence. Our approach is to develop a probabilistic description of memory mechanisms to link to the broader goals of trauma treatment. Analysis shows how critical attributes of the framework such as intervention strength and reminder strength determine success in managing intrusive memories. Validation with empirical data shows how the framework can be parameterized and predictions evaluated against observed outcomes. In this way neural mechanisms associated with memory can be combined with broader cognitive processes.

neuroscience↗