Biology subjects

Boyd, D.

Publications and source records attributed to Boyd, D..

5 recordsLinked to original sources

bioRxiv2026

Giant viruses encode vitamin K-based redox modules for lipid modification

Viruses with large DNA genomes often carry auxiliary metabolic genes that reprogram host physiology, yet their contributions to host redox and membrane homeostasis remains poorly understood. Here we report the discovery and functional reconstitution of viral homologs of vitamin K epoxide reductase (VKOR) encoded by giant viruses. Using phylogenetic and genomic context analysis, we find that viral VKOR genes are frequently located adjacent to {gamma}-carboxylase-like epoxidase and fatty acid desaturase domains, consistent with a putative modular redox pathway for membrane lipid modification. To investigate their function, we expressed viral VKORs in an Escherichia coli strain lacking disulfide bond-forming enzymes and examined both their membrane topology and activity. Remarkably, a minimal set of residue substitutions enabled proper membrane insertion and restored bacterial motility, demonstrating that viral VKORs are catalytically competent electron shuttles. Structural modeling supports their integration into the endoplasmic reticulum-like environment in the host. Finally, we show that VKORs and {gamma}-carboxylase-like epoxidase-desaturases from Fadolivirus and Yasminevirus giant viruses are expressed during infection of Vermamoeba vermiformis, where they may couple vitamin K epoxidation to desaturation-driven lipid remodeling. These findings expand the known functional repertoire of giant viruses and uncover a previously unrecognized viral strategy for manipulating host redox metabolism and membrane composition. Significance statementViruses with large DNA genomes often encode metabolic enzymes that reshape host physiology, yet their ability to control host redox and membrane composition has remained unclear. We discovered that giant viruses encode a vitamin K epoxide reductase and associated enzymes that together form a putative redox module for lipid remodeling. We reconstituted viral VKOR activity in E. coli, demonstrating that these enzymes are catalytically active. We also detected their expression, at the RNA and protein levels, during amoebal infection by two giant viruses. Our findings reveal a previously unrecognized viral strategy for coupling vitamin K redox cycling to fatty acid desaturation. This work broadens our understanding of how giant viruses manipulate host redox homeostasis and membrane architecture during infection.

microbiology↗

bioRxiv2025

Metal Ion-Releasing Glass Particles to Enhance Antibiotic Efficacy Against Cystic Fibrosis Infection

Cystic fibrosis is characterized by thickened airway mucus that impairs mucociliary clearance and promotes persistent bacterial infections. These chronic infections, primarily caused by Pseudomonas aeruginosa and Staphylococcus aureus, lead to progressive lung damage and respiratory failure, which are the leading causes of mortality in cystic fibrosis patients. Although antibiotics remain the cornerstone of treatment for such airway infections, incomplete bacterial eradication often contributes to the emergence of antibiotic resistance. This study explores whether the efficacy of conventional antibiotics can be enhanced through co-delivery with antibacterial metal ions released from borate-based bioactive glasses. To evaluate this combination therapy, we developed an in vitro airway infection model that replicates key features of the cystic fibrosis airway environment. The model incorporates a layer of bronchial epithelial cells, a mucus-like hydrogel, and bacteria deposited using an aqueous two-phase system. Multiple bioactive glass formulations were evaluated for their ability to augment antibiotic activity and enhance bacterial eradication. The results demonstrated additive or synergistic antibacterial effects against P. aeruginosa and S. aureus, while maintaining mammalian cell viability. These findings suggest that metal ion-antibiotic combination therapies delivered via bioactive glasses may improve treatment outcomes for cystic fibrosis-related infections and reduce reliance on high-dose or prolonged antibiotic regimens. Such approaches hold promise not only for cystic fibrosis patients but also for broader clinical applications where antibiotic resistance is a growing concern.

bioengineering↗

bioRxiv2024

What unexplored means: Mapping undersampled regions in natural history collections

We examined global records of accessible natural history voucher collections (with publicly available data) for terrestrial and freshwater vascular plants, fungi, freshwater fishes, birds, mammals, and herpetofauna (amphibians and reptiles) and highlight areas of the world that would be considered undersampled and sometimes called "unexplored" (i.e., have relatively low, or no evidence of, past sampling efforts) under typical Western-scientific descriptions. We also question what "unexplored" may actually mean in these contexts and explain how retiring the term in favor of more nuanced phrasing can mitigate future misunderstandings of natural history science.

ecology↗

bioRxiv2023

Diet-induced obesity impacts influenza disease severity and transmission dynamics in ferrets

Obesity, and the associated metabolic syndrome, is a risk factor for increased disease severity with a variety of infectious agents, including influenza virus. Yet the mechanisms are only partially understood. As the number of people, particularly children, living with obesity continues to rise, it is critical to understand the role of host status on disease pathogenesis. In these studies, we use a novel diet-induced obese ferret model and new tools to demonstrate that like humans, obesity resulted in significant changes to the lung microenvironment leading to increased clinical disease and viral spread to the lower respiratory tract. The decreased antiviral responses also resulted in obese animals shedding higher infectious virus for longer making them more likely to transmit to contacts. These data suggest the obese ferret model may be crucial to understanding obesitys impact on influenza disease severity and community transmission, and a key tool for therapeutic and intervention development for this high-risk population. TeaserA new ferret model and tools to explore obesitys impact on respiratory virus infection, susceptibility, and community transmission.

microbiology↗

bioRxiv2019

The mechanical stability of the worlds tallest broadleaf trees

The factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the subject of longstanding debate. Here we examine the role of mechanical stability in limiting tree height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, including the recently discovered tallest tropical tree, a 100.8 m Shorea faguetiana. We use terrestrial laser scans, in situ strain gauge data and finite-element simulations to map the architecture of tall broadleaf trees and monitor their response to wind loading. We demonstrate that a trees risk of breaking due to gravity or self-weight decreases with tree height and is much more strongly affected by tree architecture than by material properties. In contrast, wind damage risk increases with tree height despite the larger diameters of tall trees, resulting in a U-shaped curve of mechanical risk with tree height. The relative rarity of extreme wind speeds in north Borneo may be the reason it is home to the tallest trees in the tropics.

ecology↗