Biology subjects

Howe, K. L.

Publications and source records attributed to Howe, K. L..

6 recordsLinked to original sources

bioRxiv2025

Genomic and metatranscriptomic analyses reveal an active microbial hydrocarbon cycle in the photic zone

Natural hydrocarbon seeps and hydrocarbons resulting from human activities are the primary conduits by which oil enters the sea. Marine Cyanobacteria, among the most abundant photosynthetic organisms in the world, produce alkanes, an additional hydrocarbon source to the sea. Alkane production proceeds via metabolism of fatty acid intermediates with a fatty acyl-ACP reductase (FAAR) and an aldehyde-deformylating oxygenase (ADO). These alkanes can be consumed with alkane hydroxylases, including alkane 1-monooxygenase (alkB). The production and consumption of alkanes in the photic zone is termed the short-term hydrocarbon cycle (STHC). Yet, an active STHC has not been substantiated through gene expression analyses. To determine if the STHC is active in the marine photic zone we evaluated over 9000 genomes to which metatranscriptome reads from a site in the Gulf of Mexico were recruited. In these samples, FAAR and ADO expression was dominated by Prochlorococcus and to a lesser extent Synechococcus. Bacterial alkane consumption via alkB was dominated by Pseudomonadota, SAR324, and Bacteroidota alkB gene expression. Additionally, archaeal alkane consumption utilizing this same n-alkane degradation pathway was observed in the transcript data by Thermoplasmatota, classified as Marine Group II and III, the most abundant planktonic archaeal groups. Active production of alkanes in the photic zone would be an important component of marine hydrocarbon cycle and more broadly of carbon cycling. Further, consumption of hydrocarbons, regardless of source, is a fundamentally important ecosystem cleanup service provided by microbes in the ocean. ImportanceHydrocarbons in the long-term hydrocarbon cycle (LTHC) are produced over long-time scales. In comparison, hydrocarbons, specifically n-alkanes, are produced on short time scales by Cyanobacteria as part of basic cellular processes in the short-term hydrocarbon cycle (STHC). Cyanobacterial production of n-alkanes leads to an additional annual input of more than 100 million tons of hydrocarbons to the ocean. Despite the difference in time scale and source, these hydrocarbon cycles are intrinsically linked by microbes that consume n-alkanes using the same pathways for degradation. Here we show that the production and consumption in the STHC is an active cycle in the sunlit ocean, as determined by analysis of genomes and metatranscriptomes. Importantly an active STHC could support a population of alkane degrading bacteria, enabling a rapid response to oil input from a geological reservoir as part of the LTHC, through natural or anthropogenic activities, with implications for bioremediation and ultimately for marine ecosystem health.

microbiology↗

bioRxiv2024

Multi-omic Landscape of Extracellular Vesicles in Human Carotid Atherosclerotic Plaque Reveals Endothelial Communication Networks

Background: Carotid atherosclerosis is orchestrated by cell-cell communication that drives progression along a clinical continuum (asymptomatic to symptomatic). Extracellular vesicles (EVs) are cell-derived nanoparticles representing a new paradigm in cellular communication. Little is known about their biological cargo, cellular origin/destination, and functional roles in human atherosclerotic plaque. Methods: EVs were enriched via size exclusion chromatography from human carotid endarterectomy samples dissected into paired plaque and marginal zones (symptomatic n=16, asymptomatic n=13). EV cargos were assessed via whole transcriptome miRNA sequencing and mass spectrometry-based proteomics. EV multi-omics were integrated with bulk and single cell RNA-sequencing (scRNA-seq) datasets to predict EV cellular origin and ligand-receptor interactions, and multi-modal biological network integration of EV-cargo was completed. EV functional impact was assessed with endothelial angiogenesis assays. Results: Carotid plaques contained more EVs than adjacent marginal zones, with differential enrichment for EV-miRNAs and EV-proteins in key atherogenic pathways. EV cellular origin analysis suggested that tissue EV signatures originated from endothelial cells (EC), smooth muscle cells (SMC), and immune cells. Integrated tissue vesiculomics and scRNA-seq indicated complex EV-vascular cell communication that changed with disease progression and plaque vulnerability (i.e., symptomatic disease). Plaques from symptomatic patients, but not asymptomatic patients, were characterized by increased involvement of endothelial pathways and more complex ligand-receptor interactions, relative to their marginal zones. Plaque-EVs were predicted to mediate communication with ECs. Pathway enrichment analysis delineated an endothelial signature with roles in angiogenesis and neovascularization - well-known indices of plaque instability. This was validated functionally, wherein human carotid symptomatic plaque EVs induced sprouting angiogenesis in comparison to their matched marginal zones. Conclusion: Our findings indicate that EVs may drive dynamic changes in plaques through EV- vascular cell communication and effector functions that typify vulnerability to rupture, precipitating symptomatic disease. The discovery of endothelial-directed angiogenic processes mediated by EVs creates new therapeutic avenues for atherosclerosis.

cell biology↗

bioRxiv2024

Novel, active, and uncultured hydrocarbon degrading microbes in the ocean

Given the vast quantity of oil and gas input to the marine environment annually, hydrocarbon degradation by marine microorganisms is an essential ecosystem service. Linkages between taxonomy and hydrocarbon degradation capabilities are largely based on cultivation studies, leaving a knowledge gap regarding the intrinsic ability of uncultured marine microbes to degrade hydrocarbons. To address this knowledge gap, metagenomic sequence data from the Deepwater Horizon (DWH) oil spill deep-sea plume was assembled to which metagenomic and metatranscriptomic reads were mapped. Assembly and binning produced new DWH metagenome assembled genomes that were evaluated along with their close relatives, all of which are from the marine environment (38 total). These analyses revealed globally distributed hydrocarbon degrading microbes with clade specific substrate degradation potentials that have not been reported previously. For example, methane oxidation capabilities were identified in all Cycloclasticus. Further, all Bermanella encoded and expressed genes for non-gaseous n-alkane degradation; however, DWH Bermanella encoded alkane hydroxylase, not alkane 1-monooxygenase. All but one previously unrecognized DWH plume members in the SAR324 and UBA11654 coded for aromatic hydrocarbon degradation. In contrast, Colwellia were diverse in the hydrocarbon substrates they could degrade. All clades encoded nutrient acquisition strategies and response to cold temperatures, while sensory and acquisition capabilities were clade specific. These novel insights regarding hydrocarbon degradation by uncultured planktonic microbes provided missing data, allowing for better prediction of the fate of oil and gas when hydrocarbons are input to the ocean, leading to a greater understanding of the ecological consequences to the marine environment. ImportanceMicrobial degradation of hydrocarbons is a critically important process promoting ecosystem health, yet much of what is known about this process is based on physiological experiments with a few hydrocarbon substrates and cultured microbes. Thus, the ability to degrade the diversity of hydrocarbons that comprise oil and gas by microbes in the environment, particularly in the ocean, is not well characterized. Therefore, this study aimed to utilize non-cultivation based omics data to explore novel genomes of uncultured marine microbes involved in degradation of oil and gas. Analyses of newly assembled metagenomic data and metagenomic and metatranscriptomic read recruitment revealed globally distributed hydrocarbon degrading marine microbes with clade specific substrate degradation potentials that have not been previously reported. This new understanding of oil and gas degradation by uncultured marine microbes suggested that the global ocean harbors a diversity of hydrocarbon degrading Bacteria, that can act as primary agents regulating ecosystem health.

microbiology↗

bioRxiv2023

Endothelial cells secrete small extracellular vesicles bidirectionally containing distinct cargo to uniquely reprogram vascular cells in the circulation and vessel wall

Rationale: Extracellular vesicles (EVs) contain bioactive cargo including microRNAs (miRNAs) and proteins that are released by cells as a form of cell-cell communication. Endothelial cells (ECs) form the innermost lining of all blood vessels and thereby interface with cells in the circulation as well as cells residing in the vascular wall. It is unknown whether ECs have the capacity to release EVs capable of governing recipient cells within two separate compartments, and how this is affected by endothelial activation commonly seen in atheroprone regions. Objective: Given their boundary location, we propose that ECs utilize bidirectional release of distinct EV cargo in quiescent and activated states to communicate with cells within the circulation and blood vessel wall. Methods and Results: EVs were isolated from primary human aortic endothelial cells (ECs) (+/- IL-1{beta} activation), quantified, and analysed by miRNA transcriptomics and proteomics. Compared to quiescent ECs, activated ECs increased EV release, with miRNA and protein cargo that were related to atherosclerosis. RNA sequencing of EV-treated monocytes and smooth muscle cells (SMCs) revealed that EVs from activated ECs altered pathways that were pro-inflammatory and atherogenic. Apical and basolateral EV release was assessed using ECs on transwells. ECs released more EVs apically, which increased with activation. Apical and basolateral EV cargo contained distinct transcriptomes and proteomes that were altered by EC activation. Notably, basolateral EC-EVs displayed greater changes in the EV secretome, with pathways specific to atherosclerosis. In silico analysis determined that compartment-specific cargo released by the apical and basolateral surfaces of ECs can reprogram monocytes and SMCs, respectively. Conclusions: The demonstration that ECs are capable of polarized EV cargo loading and directional EV secretion reveals a novel paradigm for endothelial communication, which may ultimately enhance our ability to design endothelial-based therapeutics for cardiovascular diseases such as atherosclerosis where ECs are persistently activated. Non-standard Abbreviations and Acronyms O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/538787v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@8e62dforg.highwire.dtl.DTLVardef@1fd4adeorg.highwire.dtl.DTLVardef@3e4433org.highwire.dtl.DTLVardef@1efa1a2_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract: Polarized endothelial extracellular vesicle communication with luminal and abluminal vascular cellsEndothelial cell small extracellular vesicle (EC-EV) release from apical (luminal) and basolateral (abluminal) surfaces in quiescence and after endothelial activation. Quiescent EC-EVs are depicted in blue (bright blue=apical, light blue=basolateral), while activated EC-EVs are depicted in red (bright red=apical, light red=basolateral). Luminal monocyte is represented in purple with upregulation of pro-inflammatory transcripts (bright purple) after uptake of activated EC-EVs from the apical surface, compared to uptake of quiescent apical EC-EVs (light purple). Basolateral EC-EVs are taken up by an abluminal resident smooth muscle cell depicted in yellow. Smooth muscle cell uptake of activated basolateral EC-EVs with upregulation of pro-inflammatory/pro-atherogenic transcripts (bright yellow), as compared to uptake of quiescent EC-EVs (light yellow).

cell biology↗

bioRxiv2020

The Ensembl COVID-19 resource: Ongoing integration of public SARS-CoV-2 data

The COVID-19 pandemic has seen unprecedented use of SARS-CoV-2 genome sequencing for epidemiological tracking and identification of emerging variants. Understanding the potential impact of these variants on the infectivity of the virus and the efficacy of emerging therapeutics and vaccines has become a cornerstone of the fight against the disease. To support the maximal use of genomic information for SARS-CoV-2 research, we launched the Ensembl COVID-19 browser, incorporating a new Ensembl gene set, multiple variant sets (including novel variation calls), and annotation from several relevant resources integrated into the reference SARS-CoV-2 assembly. This work included key adaptations of existing Ensembl genome annotation methods to model ribosomal slippage, stringent filters to elucidate the highest confidence variants and utilisation of our comparative genomics pipelines on viruses for the first time. Since May 2020, the content has been regularly updated and tools such as the Ensembl Variant Effect Predictor have been integrated. The Ensembl COVID-19 browser is freely available at https://covid-19.ensembl.org.

bioinformatics↗

bioRxiv2020

Extensive genomic and transcriptomic variation defines the chromosome-scale assembly of Haemonchus contortus, a model gastrointestinal worm

BackgroundHaemonchus contortus is a globally distributed and economically important gastrointestinal pathogen of small ruminants, and has become the key nematode model for studying anthelmintic resistance and other parasite-specific traits among a wider group of parasites including major human pathogens. Two draft genome assemblies for H. contortus were reported in 2013, however, both were highly fragmented, incomplete, and differed from one another in important respects. While the introduction of long-read sequencing has significantly increased the rate of production and contiguity of de novo genome assemblies broadly, achieving high quality genome assemblies for small, genetically diverse, outcrossing eukaryotic organisms such as H. contortus remains a significant challenge. ResultsHere, we report using PacBio long read and OpGen and 10X Genomics long-molecule methods to generate a highly contiguous 283.4 Mbp chromosome-scale genome assembly including a resolved sex chromosome. We show a remarkable pattern of almost complete conservation of chromosome content (synteny) with Caenorhabditis elegans, but almost no conservation of gene order. Long-read transcriptome sequence data has allowed us to define coordinated transcriptional regulation throughout the life cycle of the parasite, and refine our understanding of cis- and trans-splicing relative to that observed in C. elegans. Finally, we use this assembly to give a comprehensive picture of chromosome-wide genetic diversity both within a single isolate and globally. ConclusionsThe H. contortus MHco3(ISE).N1 genome assembly presented here represents the most contiguous and resolved nematode assembly outside of the Caenorhabditis genus to date, together with one of the highest-quality set of predicted gene features. These data provide a high-quality comparison for understanding the evolution and genomics of Caenorhabditis and other nematodes, and extends the experimental tractability of this model parasitic nematode in understanding pathogen biology, drug discovery and vaccine development, and important adaptive traits such as drug resistance.

genomics↗