Biology subjects

Turner, M. A.

Publications and source records attributed to Turner, M. A..

18 recordsLinked to original sources

bioRxiv2026

Laboratory efficacy of a solar-powered spatial repellent device against Anopheles mosquitoes

Spatial repellents represent a promising approach to complement existing malaria vector control interventions by reducing contact between mosquitoes and humans. However, the efficacy of passive spatial repellent devices may be affected by environmental conditions, particularly temperature and airflow, which can influence the release of volatile active ingredients. Active-release devices may provide more consistent delivery of spatial repellent compounds. We investigated the efficacy of a commercially available battery-powered spatial repellent device and a low-power solar-powered device designed for potential use in Africa. Laboratory trials were conducted to evaluate the efficacy of the two spatial repellent devices against Anopheles mosquitoes. Protective efficacy was assessed by comparing mosquito probing on human participants during spatial-repellent and control tests. The effect of the devices on mosquito entry into the test chamber was also assessed. The protective efficacy was 86% with the commercial battery-powered device and 80% with the low-power solar-powered device. A Wilcoxon rank-sum test showed that there was no significant difference between the performance of the two devices in terms of protective efficacy (p = 0.856) or entry inhibition (p = 0.7989). The low-power device could be charged using a small, household-level photovoltaic panel, to provide a potentially practical means of delivering spatial repellents in off-grid settings.

ecology↗

bioRxiv2025

Circuit specific specialization of human basal ganglia astrocytes

Astrocytes shape synapses and circuits, yet human basal ganglia astrocyte diversity is incompletely defined. We built a multimodal atlas by integrating single-nucleus RNA-sequencing and chromatin accessibility with DNA methylation, 3D chromatin conformation, and spatial transcriptomics, then mapped basal ganglia programs onto a whole-brain reference. Astrocytes segregated into three anatomical subgroups spanning striatal gray matter, extra-striatal gray matter, and white matter, with subgroup-biased neurotransmitter transporters and synapse-associated programs consistent with differences in dominant afferent input. Within striatum, dorsal and ventral astrocyte populations aligned with distinct microcircuits and were conserved in nonhuman primates. A deep learning sequence model identified subgroup-associated enhancer code and, when benchmarked against published enhancer-AAV datasets, supported the design of candidate viral tools to target basal ganglia astrocyte programs in vivo. Together, these data define major axes of human astrocyte specialization and provide a framework for cell type-specific dissection of basal ganglia function.

neuroscience↗

bioRxiv2025

Cross-species consensus atlas of the primate basal ganglia

The basal ganglia (BG) are conserved brain regions essential for motor control, learning, emotion, and cognition, and are implicated in neurological and psychiatric disease. Yet a unified cross-species taxonomy of BG cell types is lacking, limiting translation of BG circuit mechanisms, interpretation of human genetic risk, and development of cell type-targeted tools. We present a multiomic consensus atlas of 1.8 million nuclei from human, macaque, and marmoset spanning eight BG structures. Integrating cross-species gene expression, open chromatin, and spatial profiling enables definition of conserved and divergent cell types. Alignment to existing mouse and human atlases identifies 61 homologous cell types conserved over 80 million years. We identify a STRd D2 StrioMat Hybrid medium spiny neuron (MSN) type with molecular, electrophysiological, and morphological features that clarify hybrid MSN identities. Comparative cis-regulatory analysis reveals conserved sequence grammars that encode cell identity and inform viral targeting strategies, providing a foundational resource for BG evolution, function, and disease.

neuroscience↗

bioRxiv2025

A cross-species spatial transcriptomic atlas of the human and non-human primate basal ganglia

The basal ganglia are interconnected subcortical nuclei with complex topographical organization that orchestrate goal-directed behaviors and are implicated in neurodegenerative movement disorders. We generated a cellular-resolution, spatial transcriptomic atlas of the basal ganglia in human, rhesus macaque, and common marmoset, sampling over one million cells in each species. By integrating spatial data with a cross-species, consensus snRNA-seq cell type taxonomy, this atlas reveals conserved principles of molecular organization within and across structures. The cellular architecture is complex but highly stereotyped, with gene expression gradients superimposed onto discrete compartments. Extensive spatial sampling illuminates 3D gradients of molecular organization in the striatum and reveals cell type-specific core and shell compartments in the primate internal globus pallidus, which is conserved with mouse. This unified, cross-species spatial transcriptomic atlas will be a foundational resource for characterizing the molecular and functional organization of the basal ganglia and their roles in health and disease.

neuroscience↗

bioRxiv2025

Spatial patterning of transcriptional and regulatory programs in the primate subcortex

Mammalian brain cell identity is shaped by intrinsic factors and external context. We present a spatially resolved transcriptomic and gene regulatory atlas of cell types across all subcortical regions in a primate, the common marmoset. Dense sampling and cross-species integration revealed spatially precise neuronal assemblies, including in complex midbrain and diencephalic structures. Chromatin accessibility and transcriptional identity are spatially tuned within and across subcortical structures; spatial gradients within hippocampal subfields are orchestrated by graded transcription factors acting through graded enhancers. The primate-expanded thalamic GABAergic population shares transcriptional and regulatory syntax with conserved midbrain populations, reflecting an evolutionary adaptation compared with rodents. Similar regional expression across cell types can arise by distinct regulatory architectures, as for telencephalic astrocytes and neurons. Conversely, distant cell types can share regulatory programs despite divergent identities: striatal GABAergic medium spiny neurons and telencephalic glutamatergic neurons share a postsynaptic regulatory program despite divergent lineage, region, and neurotransmitter identity.

neuroscience↗

bioRxiv2025

Exploring the correspondence between gene expressionand thalamic nuclei using the THALMANAC resource

The thalamus connects the sensory organs and major subcortical brain regions with the neocortex. The thalamus has long been divided into multiple discrete nuclei, based on cytoarchitecture, histochemical stains, and mesoscale connectivity. However, thalamic nuclei do not completely describe thalamic organization. For example, some boundaries between thalamic nuclei are disputed, whereas other nuclei are known to contain subdomains with distinct connectivity and function. Moreover, the correspondence between cellular gene expression and other properties of thalamic projection neurons remains to be established. Spatial analysis of single cell gene expression provides a basis for reevaluating thalamic organization. We present the THALMANAC, (THALamusMERFISH ANalysis and ACcess) a Findable, Accessible, Interoperable, Reusable and Reproducible (FAIRR) resource for exploring and analyzing single-cell transcriptomic variation in the thalamus. The THALMANAC provides streamlined access to thalamic gene expression data registered to the common coordinate framework and tools for quantitative analysis and visualization of these data, all encapsulated in a reproducible, cloud computing platform. Using this resource, we find that gene expression generally supports the parcellation of thalamus into distinct nuclei. Some nuclei, such as the anteromedial nucleus, are additionally composed of discrete subdomains, while other nuclei share patterns of gene expression or are arrayed on a spatial gradient of gene expression. The THALMANAC establishes spatial transcriptomic data as a foundation for delineating thalamic organization. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/679413v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1d517fcorg.highwire.dtl.DTLVardef@119dccdorg.highwire.dtl.DTLVardef@ef2cd6org.highwire.dtl.DTLVardef@68adac_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Beyond benchmarking: an expert-guided consensus approach to spatially aware clustering

Spatial omics technologies have revolutionized the study of tissue architecture and cellular heterogeneity by integrating molecular profiles with spatial localization. In spatially resolved transcriptomics, delineating higher-order anatomical structures is critical for understanding how cellular organization affects tissue and organ function. Since 2020, more than 50 spatially aware clustering (SAC) methods have been developed for this purpose. However, the reliability of current benchmarks is undermined by their narrow focus on Visium and brain tissue datasets, as well as incorrect interpretation of manual annotation as ground truth. Here, we present SACCELERATOR, a community-driven, extensible framework that standardizes data formatting, method integration, and metric evaluation, and is designed to rapidly incorporate new methods and datasets. SACCELERATOR currently includes 22 SAC methods applied to 15 datasets spanning 9 technologies and diverse tissue types. Our analysis revealed substantial limitations in the generalizability and reproducibility of SAC methods across tissues and platforms. We also demonstrate that anatomical labels commonly used as ground truths are often biased, potentially error-prone, and, in some cases, unsuitable for benchmarking efforts. Rather than scoring and comparing methods, we propose a consensus-guided workflow that aggregates clustering results to generate consensus representations. Descriptive spatial metrics highlight areas of high entropy where method disagreement is highest, enabling targeted feedback for tissue experts. Applied to brain and cancer datasets, this approach uncovered biologically meaningful patterns overlooked by individual methods and manual annotations. Our results underscore the need for iterative, expert-in-the-loop analysis and reveal that traditional evaluation metrics do not always capture the subjective qualities of results. By improving tissue annotation and addressing key benchmarking limitations, SACCELERATOR provides a robust foundation for advancing spatial omics research.

genomics↗

bioRxiv2025

Novel Fluorescent and Photoconvertible Fusions Reveal Dorsal Activator Dynamics

Over the last two decades, new in vivo and in cellulo imaging technologies have uncovered the inherently dynamic nature of transcriptional regulation in embryonic development and, in particular, in the fruit fly D. melanogaster. These technologies have made it possible to characterize the subnuclear and single-molecule dynamics of transcription factors. However, a lack of appropriate fluorescent protein fusions has, until now, limited these studies to only a few of the dozens of important transcription factors in the fruit fly gene regulatory network dictating early development. Here, we report the creation of four new fluorescent protein fusions to Dorsal, a member of the NF-{kappa}B/Rel family that initiates dorsal-ventral patterning. We generated and characterized two bright fluorescent protein fusions for Dorsal, meGFP and mNeonGreen, and two photoconvertible fluorescent protein fusions, mEos4a and Dendra2. We show that removal of the DsRed2 cassette commonly used to mark the CRISPR integration restores endogenous Dorsal mRNA and protein levels and enables the fusion allele to rescue a dorsal null allele, meeting the gold standard for endogenous function of a tagged protein in a fruit fly. We then demonstrate that our bright fluorescent protein fusions can be used to dissect the spatiotemporal dynamics of stable Dorsal clusters that traverse the nucleoplasm and uncovered that these clusters preferentially interact with active sites of Dorsal-modulated transcription. We further demonstrate that our photoconvertible fluorescent protein fusions make it possible to detect individual molecules of Dorsal in the nuclei of developing embryos. These new fluorescent protein fusions constitute a valuable resource for the community to elucidate the role of Dorsal activator dynamics in dictating fruit fly early embryonic development.

developmental biology↗

bioRxiv2025

Global maps of transcription factor properties reveal threshold-based formation of DNA-bound and mobile clusters

The relationship between bulk transcription factor concentration and DNA binding has been a central question in gene regulation for decades. Recent studies propose that DNA-bound transcription factor hubs, or clusters, aid in fast and precise transcriptional interpretation. Using live imaging techniques, we quantify the concentration, binding, and mobility of the morphogen Dorsal (Dl), both in bulk and in clusters, in Drosophila blastoderm embryo. Our experiments encompass multiple length and time scales, allowing us to obtain a nucleus-wide view of the mechanism connecting hub formation to bulk Dl concentration. Our results show that previously unobserved, slowly-moving clusters of Dl are present, in addition to the expected populations of freely mobile and DNA-bound Dl. Furthermore, both mobile clusters and DNA-bound Dl appear only once a threshold concentration in the nucleus is surpassed, a behavior consistent with liquid-liquid phase separation. Thus, our work elucidates how bulk transcription factor concentration dictates the formation and spatiotemporal changes of different populations needed for gene regulation.

developmental biology↗

bioRxiv2025

Transcription factor hubs exhibit gene-specific properties that tune expression

Transcription factors (TFs) form dynamic, high-concentration clusters, condensates, or hubs, proposed to increase TF binding frequency at target enhancers. However, how enhancer sequence shapes hub properties remains unclear. We developed a live-imaging based framework to quantify the spatiotemporal relationship between TF hubs and actively transcribed genes in live Drosophila embryos. Examining hubs formed by the TF Dorsal across enhancers with defined binding-site composition, we find that hub enrichment and persistence scale with the number of Dorsal binding motifs. However, these hub properties do not predict transcriptional bursts for a given enhancer. Combining quantitative imaging with computational modeling, we show that Dorsal hub formation can be explained by TF-DNA binding kinetics alone. These findings support a model in which TF hubs emerge from enhancer-encoded TF-DNA interactions rather than higher-order regulatory assemblies.

biophysics↗

bioRxiv2024

Targeted mutagenesis of specific genomic DNA sequences in animals for the in vivo generation of variant libraries

Understanding how the number, placement and affinity of transcription factor binding sites dictates gene regulatory programs remains a major unsolved challenge in biology, particularly in the context of multicellular organisms. To uncover these rules, it is first necessary to find the binding sites within a regulatory region with high precision, and then to systematically modulate this binding site arrangement while simultaneously measuring the effect of this modulation on output gene expression. Massively parallel reporter assays (MPRAs), where the gene expression stemming from 10,000s of in vitro-generated regulatory sequences is measured, have made this feat possible in high-throughput in single cells in culture. However, because of lack of technologies to incorporate DNA libraries, MPRAs are limited in whole organisms. To enable MPRAs in multicellular organisms, we generated tools to create a high degree of mutagenesis in specific genomic loci in vivo using base editing. Targeting GFP integrated in genome of Drosophila cell culture and whole animals as a case study, we show that the base editor AIDevoCDA1 stemming from sea lamprey fused to nCas9 is highly mutagenic. Surprisingly, longer gRNAs increase mutation efficiency and expand the mutating window, which can allow the introduction of mutations in previously untargetable sequences. Finally, we demonstrate arrays of >20 gRNAs that can efficiently introduce mutations along a 200bp sequence, making it a promising tool to test enhancer function in vivo in a high throughput manner.

genetics↗

bioRxiv2023

Activation of the TRIF pathway and downstream targets results in the development of precancerous lesions during infection with Helicobacter.

Helicobacter pylori (H. pylori) infection is an established cause of many digestive diseases, including gastritis, peptic ulcers, and gastric cancer. However, the mechanism by which infection with H. pylori causes these disorders is still not clearly understood. This is due to insufficient knowledge of pathways that promote H. pylori-induced disease progression. We have established a Helicobacter-induced accelerated disease progression mouse model, which involves infecting mice deficient in the myeloid differentiation primary response 88 gene (Myd88-/-) with H. felis. Using this model, we report here that that progression of H. felis-induced inflammation to high-grade dysplasia was associated with activation of type I interferon (IFN-I) signaling pathway and upregulation of related downstream target genes, IFN-stimulated genes (ISGs). These observations were further corroborated by the enrichment of ISRE motifs in the promoters of upregulated genes. Further we showed that H. felis-induced inflammation in mice deficient in Toll/interleukin-1 receptor (TIR)-domain-containing adaptor inducing interferon-{beta} (TRIF, TrifLps2) did not progress to severe gastric pathology, indicating a role of the TRIF signaling pathway in disease pathogenesis and progression. Indeed, survival analysis in gastric biopsy samples from gastric cancer patients illustrated that high expression of Trif was significantly associated with poor survival in gastric cancer.

cancer biology↗

bioRxiv2021

Predictive modeling reveals that higher-order cooperativity drives transcriptional repression in a synthetic developmental enhancer

A challenge in quantitative biology is to predict output patterns of gene expression from knowledge of input transcription factor patterns and from the arrangement of binding sites for these transcription factors on regulatory DNA. We tested whether widespread thermodynamic models could be used to infer parameters describing simple regulatory architectures that inform parameter-free predictions of more complex enhancers in the context of transcriptional repression by Runt in the early fruit 2y embryo. By modulating the number and placement of Runt binding sites within an enhancer, and quantifying the resulting transcriptional activity using live imaging, we discovered that thermodynamic models call for higher-order cooperativity between multiple molecular players. This higher-order cooperativity capture the combinatorial complexity underlying eukaryotic transcriptional regulation and cannot be determined from simpler regulatory architectures, highlighting the challenges in reaching a predictive understanding of transcriptional regulation in eukaryotes and calling for approaches that quantitatively dissect their molecular nature.

biophysics↗

bioRxiv2021

Minimal synthetic enhancers reveal control of the probability of transcriptional engagement and its timing by a morphogen gradient

How enhancers interpret morphogen gradients to generate spatial patterns of gene expression is a central question in developmental biology. Although recent studies have begun to elucidate that enhancers can dictate whether, when, and at what rate a promoter will engage in transcription, the complexity of endogenous enhancers calls for theoretical models with too many free parameters to quantitatively dissect these regulatory strategies. To overcome this limitation, we established a minimal synthetic enhancer system in embryos of the fruit 2y Drosophila melanogaster. Here, a gradient of the Dorsal activator is read by a single Dorsal binding site. By quantifying transcriptional activity using live imaging, our experiments revealed that this single Dorsal binding site is capable of regulating whether promoters engage in transcription in a Dorsal concentration-speci1c manner. By modulating binding-site aZnity, we determined that a genes decision to engage in transcription and its transcriptional onset time can be explained by a simple theoretical model where the promoter has to traverse multiple kinetic barriers before transcription can ensue. The experimental platform developed here pushes the boundaries of live-imaging in studying gene regulation in the early embryo by enabling the quanti1cation of the transcriptional activity driven by a single transcription factor binding site, and making it possible to build more complex enhancers from the ground up in the context of a dialogue between theory and experiment.

developmental biology↗

bioRxiv2020

Quantitative characterization of the eukaryotic transcription cycle using live imaging and statistical inference

The eukaryotic transcription cycle consists of three main steps: initiation, elongation, and cleavage of the nascent RNA transcript. Although each of these steps can be regulated as well as coupled with each other, their in vivo dissection has remained challenging because available experimental readouts lack sufficient spatiotemporal resolution to separate the contributions from each of these steps. Here, we describe a novel application of Bayesian inference techniques to simultaneously infer the effective parameters of the transcription cycle in real time and at the single-cell level using a two-color MS2/PP7 reporter gene and the developing fruit fly embryo as a case study. Our method enables detailed investigations into cell-to-cell variability in transcription-cycle parameters as well as single-cell correlations between these parameters. These measurements, combined with theoretical modeling, suggest a substantial variability in the elongation rate of individual RNA polymerase molecules. We further illustrate the power of this technique by uncovering a novel mechanistic connection between RNA polymerase density and nascent RNA cleavage efficiency. Thus, our approach makes it possible to shed light on the regulatory mechanisms in play during each step of the transcription cycle in individual, living cells at high spatiotemporal resolution.

biophysics↗

bioRxiv2020

Extraction-free COVID-19 (SARS-CoV-2) diagnosis by RT-PCR to increase capacity for national testing programmes during a pandemic

Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus disease 2019 (COVID-19), a respiratory tract infection. The standard molecular diagnostic test is a multistep process involving viral RNA extraction and real-time quantitative reverse transcriptase PCR (qRT-PCR). Laboratories across the globe face constraints on equipment and reagents during the COVID-19 pandemic. We have developed a simplified qRT-PCR assay that removes the need for an RNA extraction process and can be run on a real-time thermal cycler. The assay uses custom primers and probes, and maintains diagnostic sensitivity within 98.0% compared to the assay run on a high-throughput, random-access automated platform, the Panther Fusion (Hologic). This assay can be used to increase capacity for COVID-19 testing for national programmes worldwide.

molecular biology↗

bioRxiv2019

Kinesin-1 and dynein use distinct mechanisms to bypass obstacles

Kinesin-1 and cytoplasmic dynein are microtubule (MT) motors that transport intracellular cargos. It remains unclear how these motors move along MTs densely coated with obstacles of various sizes in the cytoplasm. Here, we tested the ability of single and multiple motors to bypass synthetic obstacles on MTs in vitro. Contrary to previous reports, we found that mammalian dynein is highly capable of bypassing obstacles. Unlike dynein, single kinesin motors stall in the presence of obstacles, consistent with their inability to take sideways steps to neighboring protofilaments. Kinesins overcome this limitation when working in teams, bypassing obstacles as effectively as multiple dyneins. Cargos driven by multiple kinesin or dyneins are also capable of rotating around the MT to bypass large obstacles. These results suggest that multiplicity of motors is required not only for transporting cargos over long distances and generating higher forces, but also for maneuvering of the cargos on obstacle-coated MT surfaces.

biophysics↗

bioRxiv2018

Drug prescription pattern in European neonatal units

BackgroundHospitalized neonates receive the highest number of drugs compared to all other age groups, but consumption rates vary between studies depending on patient characteristics and local practices. There are no large scale international studies on drug use in neonatal units. We aimed to describe drug use in European neonatal units and characterize its associations with geographic region and gestational age (GA).\n\nMethodsA one-day point prevalence study (PPS) was performed as part of the European Study of Neonatal Exposure to Excipients (ESNEE) from January to June 2012. All neonatal prescriptions and demographic data were registered in a web-based database. The impact of GA and region on prescription rate were analyzed with logistic regression.\n\nResultsIn total, 21 European countries with 89 neonatal units participated. Altogether 2173 prescriptions given to 726 neonates were registered. The 10 drugs with the highest prescription rate were multivitamins, vitamin D, caffeine, gentamicin, amino acids for parenteral nutrition, phytomenadione, ampicillin, benzylpenicillin, fat emulsion for parenteral nutrition and probiotics. The six most commonly prescribed ATC groups (alimentary tract and metabolism, blood and blood-forming organs, systemic anti-infectives, nervous, respiratory and cardiovascular system) covered 98% of prescriptions. GA significantly affected the use of all commonly used drug groups. Geographic region influenced the use of alimentary tract and metabolism, blood and blood-forming organs, systemic anti-infectives, nervous and respiratory system drugs.\n\nConclusionsWhile GA-dependent differences in neonatal drug use were expected, regional variations (except for systemic anti-infectives) indicate a need for cooperation in developing harmonized evidence-based guidelines and suggest priorities for collaborative work.

pharmacology and toxicology↗