Biology subjects

Miles, M.

Publications and source records attributed to Miles, M..

8 recordsLinked to original sources

bioRxiv2025

Microbiome-behavior coupling shapes infant adaptation to early maternal unpredictability

We asked whether infant microbiome composition, together with infants behavioral responses to early maternal unpredictability, can offer novel mechanistic insights into behavioral phenotypic variation in human development. Maternal unpredictability was computed as the entropy rate of transitions among maternal sensory signals during naturalistic mother-infant interaction (n=256 dyads; 2-6 months). Infant visual orienting behavior (VOB) was indexed by infants simultaneous gaze shifts to and from the mother. Higher maternal unpredictability predicted more frequent VOB shifts, indicating a mature-for-age profile, and longitudinally forecast poorer inhibitory control at 19-28 months. A subgroup of infants with high maternal unpredictability and high VOB had inhibitory control outcomes closer to those of infants who experienced low maternal unpredictability, suggesting VOB strategy might buffer against the effects of high maternal unpredictability. In participants with metagenomic data (n=93), VOB was associated with taxonomic and functional gut microbial profiles along a Bifidobacterium breve to Bifidobacterium longum axis. Neuroactive gene-set enrichment analysis linked VOB to increase in tryptophan synthesis and glutamate synthesis genes. In contrast, maternal unpredictability showed depletions of GABA and tryptophan synthesis in the unique-effects model and, when VOB and the maternal unpredictability by VOB term were included, enrichment of acetate synthesis and quinolinic acid degradation. Notably, the maternal unpredictability by VOB interactions for tryptophan and glutamate were negative, indicating that the VOB-pathway coupling attenuates as unpredictability increases. Together, these findings support a framework in which maternal unpredictability is the environmental challenge, infant VOB expresses the behavioral strategy, and microbial metabolism modulates whether that strategy is biochemically feasible. TeaserInfant gut microbiome is linked to infant behavioral responses to maternal unpredictability, which in turn impacts how they learn to control their actions.

neuroscience↗

bioRxiv2025

Neural population dynamics of direct electrical stimulation of neocortex

Intracranial electrical stimulation is foundational in neuroscience and clinical neuromodulation, yet how applied electrical fields engage neural tissue and influences perception remains unclear. Using three orthogonal Neuropixels probes in mouse visual areas, we recorded extracellular voltages and spikes with sub-millisecond resolution in three dimensions around a stimulation source. The evoked potential extended asymmetrically and grew sub-linearly with amplitude, influenced by anatomical heterogeneity. Increasing amplitude increased the density, but not spatial extent, of directly responsive neurons, but fewer than 5% of neurons within the evoked potential were activated. Fast-spiking interneurons were recruited nearer the source, whereas pyramidal neurons showed anisotropic activation. Direct responses were polarity- and amplitude-selective. Sparse direct spiking drove large, asymmetric cortical responses and modulated >50% of neurons at higher amplitudes. Perceptually, mice weakly detected single pulses, and performance did not improve with amplitude. Thus, anatomy and spatiotemporal patterning--not spike counts--govern physiological and perceptual impact, informing biomimetic, multi-contact prostheses.

neuroscience↗

bioRxiv2025

Cell divisions both challenge and refine tissue boundaries in the Drosophila embryo

Tissue boundaries pattern embryos, suppress tumours, and provide directional cues. Tissue boundaries are associated with supracellular cables formed by actin and the molecular motor non-muscle myosin II. Actomyosin cables generate tension that prevents cell mixing. Whether other cellular behaviours contribute to the formation of linear interfaces between cell populations remains unclear. In the Drosophila embryo, an actomyosin-based boundary separates the ectoderm from the mesectoderm, a group of neuronal and glial progenitors. Mathematical modelling predicted that cell divisions in the ectoderm challenge the mesectoderm-ectoderm (ME) boundary. Consistent with this, suppressing ectoderm cell divisions in vivo prevented cell mixing across the ME boundary when actomyosin-based tension was lost. Our mathematical model also predicted that cell divisions sharpen the ME boundary by reducing tension and increasing cell motility in the ectoderm. We found that inhibiting ectoderm divisions in vivo reduced boundary linearity. Using laser ablation and cell tracking, we demonstrated that cell divisions reduced junctional tension and increased cell movement in the ectoderm. Together, our results reveal that cell divisions facilitate cellular rearrangements to increase fluidity in a novel mechanism for boundary refinement.

developmental biology↗

bioRxiv2024

Evaluating a Novel High-Density EEG Sensor Net Structure for Improving Inclusivity in Infants with Curly or Tightly Coiled Hair

Electroencephalography (EEG) is an important tool in the field of developmental cognitive neuroscience for indexing neural activity. However, racial biases persist in EEG research that limit the utility of this tool. One bias comes from the structure of EEG nets/caps that do not facilitate equitable data collection across hair textures and types. Recent efforts have improved EEG net/cap design, but these solutions can be time-intensive, reduce sensor density, and are more difficult to implement in younger populations. The present study focused on testing EEG sensor net designs over infancy. Specifically, we compared EEG data quality and retention between two high-density saline-based EEG sensor net designs from the same company (Magstim EGI, Whitland, UK) within the same infants during a baseline EEG paradigm. We found that within infants, the tall sensor nets resulted in lower impedances during collection, including lower impedances in the key online reference electrode for those with greater hair heights and resulted in a greater number of usable EEG channels and data segments retained during pre-processing. These results suggest that along with other best practices, the modified tall sensor net design is useful for improving data quality and retention in infant participants with curly or tightly-coiled hair.

neuroscience↗

bioRxiv2024

Analysis of justification for and gender bias in author order among those contributing equally

The practice of designating two or more authors as equal contributors (EC) on a scientific publication is increasingly common as a form of sharing credit. However, EC authors are often unclearly attributed on CVs or citation engines, and it is unclear how research teams determine author order within an EC listing. In response to studies showing that male authors were more likely to be placed first in an EC listing, the American Society of Microbiology (ASM) required that authors explain the reasons for author order beginning in 2020. In this study we analyze data from over 2500 ASM publications to see how this policy affected gender bias and how research teams are making decisions on author order. Data on publications from 2018-2021 show that gender bias was largely nonsignificant both before and after authors were asked by ASM to provide an EC statement. The most likely reasons for EC order included alphabetical order, seniority, and chance, although there were differences for publications from different geographic regions. However, many research teams used unique methods in order selection, highlighting the importance of EC statements to provide clarity for readers, funding agencies, and tenure committees.

scientific communication and education↗

bioRxiv2019

Ecological divergence and hybridization of Neotropical Leishmania parasites

The tropical Andes is an important natural laboratory to understand speciation and diversification in many taxa. Here, we examined the evolutionary history of parasites of the Leishmania braziliensis species complex based on whole genome sequencing of 67 isolates from 47 localities in Peru. We firstly show the origin of near-clonal Andean Leishmania lineages that diverged from admixed Amazonian ancestors, accompanied by a significant reduction in genome diversity and large structural variations implicated in host-parasite interactions. Beside a clear dichotomy between Andean and Amazonian species, patterns of population structure were strongly associated with biogeographical origin. Molecular clock analyses and ecological niche modeling suggested that the history of diversification of the Andean lineages is limited to the Late Pleistocene and intimately associated with habitat contractions driven by climate change. These results support a wider model on trypanosomatid evolution where major parasite lineages emerge through ecological fitting. Second, genome-scale analyses provided evidence of meiotic recombination between Andean and Amazonian Leishmania species, resulting in full-genome hybrids. The mitochondrial genome of these hybrids consisted of homogeneous uniparental maxicircles, but minicircles originated from both parental species, leaving a mosaic ancestry of minicircle-encoded guide RNA genes. We further show that mitochondrial minicircles - but not maxicircles - show a similar evolutionary pattern as the nuclear genome, suggesting that biparental inheritance of minicircles is universal and may be important to alleviate maxicircle-nuclear incompatibilities. By comparing full nuclear and mitochondrial genome ancestries, our data expands our appreciation on the genetic consequences of diversification and hybridization in parasitic protozoa.

genomics↗

bioRxiv2019

Assessing the role of long-noncoding RNA in nucleus accumbens in subjects with alcohol dependence

Recently, long noncoding RNA (lncRNA) were implicated in the etiology of alcohol dependence (AD). As lncRNA provide another layer of complexity to the transcriptome, assessing their expression in the brain is the first critical step towards understanding lncRNA functions in AD. To that end, we profiled the expression of lncRNA and protein coding genes (PCG) in nucleus accumbens (NAc) from 41 subjects with AD and 41 controls. At false discovery rate (FDR) of 5%, we identified 69 and 309 differentially expressed lncRNA and PCG genes, respectively. Using co-expression network analyses, we identified three lncRNA and five PCG modules significantly correlated with AD at Bonferroni adj. p[≤]0.05. To better understand lncRNA functions, we integrated the lncRNA and PCG hubs from the significant AD modules; at FDR of 5%, we identified 3 151 positive and 2 255 negative correlations supporting the functional role of lncRNA in the development of AD. Gene enrichment analysis revealed that PCG significantly correlated with lncRNA are, among others, enriched for neuronal and immune related processes. To highlight the mechanisms, by which genetic variants contribute to AD, we integrated lncRNA and PCG hubs with genome-wide SNP data. At FDR[≤]0.3, we identified 276 expression quantitative trait loci (eQTL), affecting the expression of 20 and 256 lncRNA and PCG hubs, respectively. Our study is the first to profile lncRNA expression in nucleus accumbens in a large postmortem alcohol brain sample and our results may provide novel insights into the regulation of the brain transcriptome across disease.

neuroscience↗

bioRxiv2019

Genomic analysis of natural intra-specific hybrids among Ethiopian isolates of Leishmania donovani

Parasites of the genus Leishmania (Kinetoplastida: Trypanosomatidae) cause widespread and devastating human diseases, ranging from self-healing but disfiguring cutaneous lesions to destructive mucocutaneous presentations or usually fatal visceral disease. Visceral leishmaniasis due to Leishmania donovani is endemic in Ethiopia where it has also been responsible for major epidemics. The presence of hybrid genotypes has been widely reported in surveys of natural populations, genetic variation reported in a number of Leishmania species, and the extant capacity for genetic exchange demonstrated in laboratory experiments. However, patterns of recombination and evolutionary history of admixture that produced these hybrid populations remain unclear, as most of the relevant literature examines only a limited number (typically fewer than 10) genetic loci. Here, we use whole-genome sequence data to investigate Ethiopian L. donovani isolates previously characterised as hybrids by microsatellite and multi-locus sequencing. To date there is only one previous study on a natural population of Leishmania hybrids, based on whole-genome sequence. The current findings demonstrate important differences. We propose hybrids originate from recombination between two different lineages of Ethiopian L. donovani occurring in the same region. Patterns of inheritance are more complex than previously reported with multiple, apparently independent, origins from similar parents that include backcrossing with parental types. Analysis indicates that hybrids are representative of at least three different histories. Furthermore, isolates were highly polysomic at the level of chromosomes with startling differences between parasites recovered from a recrudescent infection from a previously treated individual. The results demonstrate that recombination is a significant feature of natural populations and contributes to the growing body of evidence describing how recombination, and gene flow, shape natural populations of Leishmania.\n\nAuthor SummaryLeishmaniasis is a spectrum of diseases caused by the protozoan parasite Leishmania. It is transmitted by sandfly insect vectors and is responsible for an enormous burden of human suffering. In this manuscript we examine Leishmania isolates from Ethiopia that cause the most serious form of the disease, namely visceral leishmaniasis, which is usually fatal without treatment. Historically the general view was that such parasites reproduce clonally, so that their progeny are genetically identical to the founding cells. This view has changed over time and it is increasingly clear that recombination between genetically different Leishmania parasites occurs. The implication is that new biological traits such as virulence, resistance to drug treatments or the ability to infect new species of sandfly could emerge. The frequency and underlying mechanism of such recombination in natural isolates is poorly understood. Here we perform a detailed whole genome analysis on a cohort of hybrid isolates from Ethiopia together with their potential parents to assess the genetic nature of hybrids in more detail. Results reveal a complex pattern of mating and inbreeding indicative of multiple mating events that has likely shaped the epidemiology of the disease agent. We also show that some hybrids have very different relative amounts of DNA (polysomy) the implications of which are discussed. Together the results contribute to a fuller understanding of the nature of genetic recombination in natural populations of Leishmania.

genomics↗