Biology subjects

Hill, N.

Publications and source records attributed to Hill, N..

7 recordsLinked to original sources

bioRxiv2026

Bathymetric Resolution-Dependent Biases in Antarctic Benthic Biodiversity Models: Hotspots Hold, Counts Shift

Antarctic benthic organisms are highly diverse and play a critical role in the Southern Ocean ecosystem. Despite decades of sampling, vast areas of the Antarctic continental shelf remain biologically unsurveyed due to logistical and financial constraints, limiting baseline knowledge essential for effective conservation planning. Species distribution models (SDMs) allow biodiversity to be inferred in the absence of biological data by linking benthic community patterns to environmental predictors. However, the resolution of the environmental predictors, particularly bathymetry, varies significantly between regions, casting doubt about how reliably SDMs can be used to predict into regions where only coarse-resolution data are available. Here, we show that SDMs trained on high-resolution data underestimate Antarctic benthic morphospecies richness by up to 18% when applied to aggregated coarse-resolution environmental data (and up to 50% when using satellite-derived ETOPO bathymetry). Using six systematically degraded versions of high-resolution multibeam bathymetry and annotated seafloor imagery across three Antarctic regions, we evaluate SDM performance both with and without additional environmental variables. High-resolution bathymetry captures terrain complexity most effectively, but we find that the spatial distribution of richness hotspots and the median richness per cell remain consistent, provided models are applied at the same resolution at which they were trained. Our results suggest that while high-resolution bathymetry may enhance local predictions, coarse-resolution data may be more robust for regional-scale predictions, such as those used for Antarctic shelf-wide spatial planning.

ecology↗

bioRxiv2025

Climate Change, Fisheries Management, and Increases in Demersal Fish Distribution in a Southern Ocean Biodiversity Hotspot

The worlds oceans and their biodiversity are undergoing going change driven by climate change and anthropogenic impacts such as fishing. The Kerguelen Plateau is a biodiversity hotspot with many endemic fish species, furthermore the region has economic importance in supporting valuable fisheries. This region is also a climate change hotspot with known notable changes in the location of the polar front, ocean currents, and primary productivity. In this study we use data from long-term scientific trawl surveys and contemporary joint species distribution models to understand how the demersal fish assemblage of the Kerguelen Plateau has changed through time and space. The modelling indicates that most demersal species have had notable changes in their occurrence and CPUE from 2003 to 2016. This included a significant increase in species richness throughout the study period. The modelling also provides novel insights into the depth, climatic and environmental preferences for all species, including many species that were previously data limited. It is unclear whether these changes reflect shifts in the fishery, management, or the effects of climate change, but most likely a combination of all. We also found evidence of several species distributions responding to temperature variability, with species being exposed to the ongoing impacts of climate change. This new information can be used by managers and policy makers to ensure continuation of sustainable fisheries and the protection of biodiversity into the future.

ecology↗

bioRxiv2024

Exploring mechanisms of change in a Southern Ocean fishery with a co-produced network model

A key challenge in planning long-term fisheries sustainability is overcoming uncertainties in predicted changes in target populations and catch rates in response to climate change and fishery trends. We combine transdisciplinary knowledge co-production and qualitative network modelling to advance system understanding and elucidate likely responses of a Patagonian toothfish fishery to future change. We co-developed a model of the Kerguelen Plateau biophysical-socioeconomic system with knowledge holders from industry and science; the first whole-of-system qualitative network model of intermediate complexity for this region. We present new approaches for dealing with uncertainty in network structure, and for investigating how perturbations propagate through a network. Using these tools, we found multiple potential pathways of decline for toothfish population and catch, but also some possible mechanisms of increase dependent on magnitude of certain effects. Our results highlight critical information gaps, including the potential role of scavenging benthos in fishery-ecosystem interactions and likely changes in the prey-field in response to warmer water, that require filling to improve predictions for toothfish populations and catch and forward planning for the fishery.

ecology↗

bioRxiv2024

Heterologous Surface Display Reveals Conserved Complement Inhibition and Functional Diversification of Borrelia burgdorferi Elp Proteins

Lyme disease is a tick-borne spirochetosis with diverse clinical manifestations. Phenotypic variation among Borrelia burgdorferi strains correlates with variable manifestations of Lyme disease in humans; this diversity is attributed in part to variation in surface-exposed lipoproteins, which are targets of the human antibody response and contribute to tissue adhesion, immune evasion, and other host interactions. Many B. burgdorferi lipoproteins are encoded as multi-copy gene families including the OspE/F- like leader peptide (Elp) protein family. To characterize Elp allelic variants, we adapted the Pseudomonas syringae ice nucleation protein (INP) system to present B. burgdorferi lipoproteins on the surface of Escherichia coli. We identified interactions with classical complement proteins and mapped binding regions in the E. coli system. We validated interactions using recombinant proteins and B. burgdorferi surface display. By assessing potential interactions with extracellular matrix components, we identified a novel interaction between Elp proteins and perlecan, a component of mammalian basement membranes, and revealed the bifunctional nature of Elps. Our findings reveal that Elps have undergone functional diversification while maintaining classical complement inhibition mediated by potent and conserved C1s binding and demonstrate that E. coli surface display offers an efficient, cost-effective, and relatively high throughput approach to characterize B. burgdorferi lipoproteins.

microbiology↗

bioRxiv2023

Whole genome sequencing of Borrelia burgdorferi isolates reveals linked clusters of plasmid-borne accessory genome elements associated with virulence.

Lyme disease is the most common vector-borne disease in North America and Europe. The clinical manifestations of Lyme disease vary based on the genospecies of the infecting Borrelia burgdorferi spirochete, but the microbial genetic elements underlying these associations are not known. Here, we report the whole genome sequence (WGS) and analysis of 299 patient-derived B. burgdorferi sensu stricto (Bbss) isolates from patients in the Eastern and Midwestern US and Central Europe. We develop a WGS-based classification of Bbss isolates, confirm and extend the findings of previous single- and multi-locus typing systems, define the plasmid profiles of human-infectious Bbss isolates, annotate the core and strain-variable surface lipoproteome, and identify loci associated with disseminated infection. A core genome consisting of [~]800 open reading frames and a core set of plasmids consisting of lp17, lp25, lp36, lp28-3, lp28-4, lp54, and cp26 are found in nearly all isolates. Strain-variable (accessory) plasmids and genes correlate strongly with phylogeny. Using genetic association study methods, we identify an accessory genome signature associated with dissemination and define the individual plasmids and genes that make up this signature. Strains within the RST1/WGS A subgroup, particularly a subset marked by the OspC type A genotype, are associated with increased rates of dissemination. OspC type A strains possess a unique constellation of strongly linked genetic changes including the presence of lp56 and lp28-1 plasmids and a cluster of genes that may contribute to their enhanced virulence compared to other genotypes. The patterns of OspC type A strains typify a broader paradigm across Bbss isolates, in which genetic structure is defined by correlated groups of strain-variable genes located predominantly on plasmids, particularly for expression of surface-exposed lipoproteins. These clusters of genes are inherited in blocks through strain-specific patterns of plasmid occupancy and are associated with the probability of invasive infection.

microbiology↗

bioRxiv2021

Green Fluorescent Carbon Dots as Targeting Probes for LED-Dependent Bacterial Killing

The emergence of antimicrobial resistance represents a significant health and economic challenge worldwide. The slow pace of antibacterial discovery necessitates strategies for optimal use of existing agents, including effective diagnostics able to drive informed prescribing; and development of alternative therapeutic strategies that go beyond traditional small-molecule approaches. Thus, the development of novel probes able to target bacteria for detection and killing, and that can pave the way to effective theranostic strategies, is of great importance. Here we demonstrate that metal-free green-emitting fluorescent carbon dots (FCDs) synthesized from glucosamine HCl and m-phenylenediamine, and featuring 2,5-deoxyfructosazine on a robust amorphous core, can label both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) bacterial pathogens within 10 minutes of exposure. Moreover, effective killing of Gram-positive and -negative bacteria can be induced by combining FCD treatment with irradiation by LED light in the visible range. Cell-based, electron microscopy and Tandem Mass Tag (TMT) proteomic experiments indicate that FCD administration in combination with LED exposure gives rise to local heating, ROS production, and membrane- and DNA-damage, suggesting multiple routes to FCD-mediated bacterial killing. Our data identify FCDs as materials that combine facile synthesis from low-cost precursors with labelling and light-dependent killing of clinically important bacterial species, and that thus warrant further exploration as the potential bases for novel theranostics.

microbiology↗

bioRxiv2018

Description of cranial elements and ontogenetic change within Tropidolaemus wagleri (Serpentes: Crotalinae)

Tropidolaemus wagleri is a species of Asian pitviper with a geographic range including Thailand, Vietnam, Malaysia, Singapore, Bruniei, parts of Indonesia, and the Philippines. Tropidolaemus is a member of the Crotalinae subfamily, within Viperidae. The genus Tropidolaemus includes five species, and was once included within the genus Trimeresurus. While some osteologic characteristics have been noted a comprehensive description of cranial elements has not been produced for T. wagleri. An in-depth description of the cranial skeleton of Tropidolaemus wagleri lays the foundation for future projects to compare and contrast other taxa within Crotalinae and Viperidae. The chosen reference specimen was compared to the presumed younger specimens to note any variation in ontogeny. The study here provides a comprehensive description of isolated cranial elements as well as a description of ontogenetic change within the specimens observed. This study contributes to the knowledge of osteological characters in T. wagleri and provides a foundation for a long term project to identify isolated elements in the fossil record.

zoology↗