Biology subjects

Dunn, K. A.

Publications and source records attributed to Dunn, K. A..

4 recordsLinked to original sources

bioRxiv2026

Full-length 16S ribosomal RNA gene sequencing reveals dynamics of tick-adapted and environmentally derived bacteria in the microbiome of the black-legged tick, Ixodes scapularis in Nova Scotia, Canada

Lyme disease is a tick-borne illness caused by the spirochaete bacterium Borrelia (Borreliella) burgdorferi. The black-legged tick Ixodes scapularis, which transmits B. burgdorferi and several other human pathogens, is endemic to the eastern United States and, due to climate change, is rapidly expanding into central and eastern Canada. Amplification and sequencing of bacterial DNA from I. scapularis is increasingly used to monitor the presence and abundance of B. burgdorferi and associated bacteria. However, variation in the nature of molecular data collected across studies presents challenges for analysis and interpretation. Here we use full-length Oxford Nanopore 16S ribosomal RNA gene amplicon sequencing to characterize the microbiome of I. scapularis, with an explicit focus on distinguishing between tick-adapted bacteria (endosymbionts and pathogens) and environmentally acquired bacteria (external sources, including soil, vegetation or vertebrate hosts). We show that environmental dominance strength differs between these two ecological classes of bacteria, and that environmental dominance does not appear to represent stochastic background alone; environmentally derived bacterial taxa detected in tick microbiomes are not mere contaminants. Paired soil microbiome profiling from tick collection sites will be required to test whether environmental dominance and associated co-occurrence structure track with seasonal changes in exposure and environmental microbial populations.

microbiology↗

bioRxiv2025

Global Evaluation of Congenital Heart Disease-Associated Non-Coding Variants

Abstract (Summary)Genome-wide association studies (GWAS) have mapped thousands of congenital heart disease (CHD)-associated variants within non-coding regions of the genome. Non-coding variants can alter regulatory mechanisms, such as transcription factor (TF) binding control of gene expression, potentially contributing human diseases. However, with the increasing number of disease-associated variants, comprehensive functional validation remains a significant challenge. In this work, we developed a novel method called SNP Bind-n-Seq to evaluate >3,000 CHD-risk variants for allelic binding for the cardiac TFs NKX2-5, GATA4, and TBX5 in a high-throughput manner. These binding affinity data sets were coupled with a massively parallel reporter assay (MPRA) to screen CHD-risk variant genotype-dependent regulatory activity. We identified 170 variants that exhibit allelic TF binding and 187 that modulate gene expression. Combining both approaches revealed three high-confidence variants with genotype-dependent TF binding, genotype-dependent transcriptional activity, and eQTL behavior in cardiac cells. Collectively, this study provides the first combined high-throughput biochemical and functional genomic evaluation of thousands of CHD-risk variants. HighlightsO_LIAllelic binding affinity measurements of [~]9,600 variants for NKX2-5, GATA4, and TBX5 C_LIO_LIEvaluaFon of >3,000 CHD-risk variants for genotype-dependent regulatory acFvity C_LIO_LIInteracFon networks idenFfy funcFonal variants and genes involving cardiac eQTLs C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC="FIGDIR/small/691900v2_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1f2dc96org.highwire.dtl.DTLVardef@1700929org.highwire.dtl.DTLVardef@696ec4org.highwire.dtl.DTLVardef@1e724d8_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2025

Systematic investigation of Epstein-Barr virus transcriptional regulator interactions with the human genome

We systematically investigate interactions between Epstein-Barr virus (EBV) transcriptional regulators (vTRs) and the human genome. Starting with 16 known and candidate vTRs, we identify nine whose introduction into human cells results in substantial alterations to host gene expression. Genome-scale determination of vTR genomic binding events and alterations to chromatin accessibility reveals a detailed map of EBVs functional interactions with the human genome, including >100,000 vTR binding events impacting almost a quarter of all human genes. BMRF1 emerges as a potent regulator, impacting >7,000 genes and altering >37,000 chromatin regions. Our results provide new evidence that EBV RTA interacts with and stabilizes the binding of human RBPJ. Network analysis reveals that many human genes are targeted by multiple EBV vTRs, highlighting the vast coordinated impact of EBV on human gene expression. This study provides a valuable, extensive resource for examining EBV-induced alterations to human gene regulation, with data available on multiple platforms.

genomics↗

bioRxiv2023

Eukfinder: a pipeline to retrieve microbial eukaryote genomes from metagenomic sequencing data.

Whole-genome shotgun (WGS) metagenomic sequencing of microbial communities allows us to discover the functions, physiologies, and evolutionary histories of microbial prokaryote and eukaryote members of diverse ecosystems. Despite their importance, metagenomic studies of microbial eukaryotes lag behind those of prokaryotes, due to the difficulty in identifying and assembling high-quality eukaryotic genomes from WGS data. To address this problem, we have developed Eukfinder, a bioinformatics pipeline that recovers and assembles nuclear and mitochondrial genomes of eukaryotic microbes from WGS metagenomics data. As part of its workflow, it utilizes two specialized databases to classify reads based on taxonomy which can be customized to the dataset or environment of interest. We applied Eukfinder to human gut microbiome WGS metagenomic sequencing data to recover genomes from the protistan parasite Blastocystis sp., a highly prevalent colonizer of the gastrointestinal tract of humans and animals. We tested Eukfinder using both a series of simulated gut microbiome datasets, which included varying numbers of Blastocystis reads combined with bacterial reads and by using real metagenomic gut samples containing Blastocystis. We compared the results of Eukfinder with other published workflows. With sufficient reads, Eukfinder efficiently assembles high-quality near-complete nuclear and mitochondrial genomes from diverse Blastocystis subtypes from metagenomic data without the aid of a reference genome. Furthermore, with sufficient depth of sequence sampling, Eukfinder outperforms similar tools used to recover eukaryotic genomes from metagenomic data. Eukfinder will be a useful tool for reference-independent and cultivation-free study of eukaryotic microbial genomes from environmental metagenomic sequencing samples. IMPORTANCERapid advancements in next-generation sequencing technologies have made whole-genome shotgun (WGS) metagenomic sequencing an efficient method for de novo reconstruction of microbial genomes from samples taken from different environments. So far, thousands of new prokaryotic genomes have been characterized from strains or species that were unknown to science. However, the relatively large size and complexity of protistan genomes has, until recently, precluded the use of the WGS metagenomic approach to sample microbial eukaryotic diversity. The bioinformatics pipeline we developed, Eukfinder, can recover eukaryotic microbial genomes from environmental WGS metagenomic samples. By retrieving high-quality protistan genomes from diverse metagenomic samples, we can increase numbers of reference genomes available to aid future metagenomic investigations into the functions, physiologies, and evolutionary histories of eukaryotic microbes in the gut microbiome and a variety of other ecosystems.

bioinformatics↗