Publications by authors named "David M Nelson"

Bats subject to high rates of fatalities at wind-energy facilities are of high conservation concern due to the long-term, cumulative effects they have, but the impact on broader bat populations can be difficult to assess. One reason is the poor understanding of the geographic source of individual fatalities and whether they constitute migrants or more local individuals. Here, we used stable hydrogen isotopes, trace elements and species distribution models to determine the most likely summer geographic origins of three different bat species (, , and ) killed at wind-energy facilities in Ohio and Maryland in the eastern United States.

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Bird populations are declining globally. Wind and solar energy can reduce emissions of fossil fuels that drive anthropogenic climate change, yet renewable-energy production represents a potential threat to bird species. Surveys to assess potential effects at renewable-energy facilities are exclusively local, and the geographic extent encompassed by birds killed at these facilities is largely unknown, which creates challenges for minimizing and mitigating the population-level and cumulative effects of these fatalities.

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Background: Operation of wind turbines has resulted in collision fatalities for several bat species, and one proven method to reduce these fatalities is to limit wind turbine blade rotation (., curtail turbines) when fatalities are expected to be highest. Implementation of curtailment can potentially be optimized by targeting times when females are most at risk, as the proportion of females limits the growth and stability of many bat populations.

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Advancement of endogenous biomarkers for drug transporters as a tool for assessing drug-drug interactions (DDIs) depends on initial identification of biomarker candidates and relies heavily on biomarker validation and its response to reference inhibitors in vivo. To identify endogenous biomarkers of breast cancer resistance protein (BCRP), we applied metabolomic approaches to profile plasma from Bcrp, multidrug resistance protein (Mdr)1a/1b, and Bcrp/Mdr1a/1b mice. Approximately 130 metabolites were significantly altered in Bcrp and P-glycoprotein (P-gp) knockout mice, indicating numerous metabolite-transporter interactions.

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White-nose syndrome (WNS) is an emerging fungal epizootic disease that has caused large-scale mortality in several species of North American bats. The fungus that causes WNS, Pseudogymnoascus destructans (Pd), has also been detected in bat species without diagnostic signs of WNS. Although these species could play a role in WNS spread, understanding of the spatial and temporal extents of Pd occurrence on WNS-resistant species is limited.

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Renewable energy production can kill individual birds, but little is known about how it affects avian populations. We assessed the vulnerability of populations for 23 priority bird species killed at wind and solar facilities in California, USA. Bayesian hierarchical models suggested that 48% of these species were vulnerable to population-level effects from added fatalities caused by renewables and other sources.

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Due to activation of fibroblast into cancer-associated fibroblasts, there is often an increased deposition of extracellular matrix and fibrillar collagens, e.g. type III collagen, in the tumor microenvironment (TME) that leads to tumor fibrosis (desmoplasia).

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Shifting range limits are predicted for many species as the climate warms. However, the rapid pace of climate change will challenge the natural dispersal capacity of long-lived, sessile organisms such as forest trees. Adaptive responses of populations will, therefore, depend on levels of genetic variation and plasticity for climate-responsive traits, which likely vary across the range due to expansion history and current patterns of selection.

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Organisms are constantly challenged by pathogens and pests, which can drive the evolution of growth-defense strategies. Plant stomata are essential for gas exchange during photosynthesis and conceptually lie at the intersection of the physiological demands of growth and exposure to foliar fungal pathogens. Generations of natural selection for locally adapted growth-defense strategies can eliminate variation between traits, potentially masking trade-offs and selection conflicts that may have existed in the past.

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The geographic distributions of eastern and western populations suggest they could be genetically isolated, but this has rarely been assessed using genetic data. Here, we evaluate this possibility by sequencing the complete mitochondrial genome of four silver-haired bats from eastern and western populations. The three usable mitogenomes were closely associated with other Vespertilionid bats and the phylogenetic tree revealed the two western individuals grouping together to form their own clade.

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The expansion of the wind energy industry has had benefits in terms of increased renewable energy production but has also led to increased mortality of migratory bats due to interactions with wind turbines. A key question that could guide bat-related management activities is identifying the geographic origin of bats killed at wind-energy facilities. Generating this information requires developing new methods for identifying the geographic sources of individual bats.

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Understanding the factors influencing the current distribution of genetic diversity across a species range is one of the main questions of evolutionary biology, especially given the increasing threat to biodiversity posed by climate change. Historical demographic processes such as population expansion or bottlenecks and decline are known to exert a predominant influence on past and current levels of genetic diversity, and revealing this demo-genetic history can have immediate conservation implications. We used a whole-exome capture sequencing approach to analyze polymorphism across the gene space of red spruce ( Sarg.

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Extracellular adenosine, produced through the activity of ecto-5'-nucleotidase CD73, elicits potent immunosuppressive effects, and its upregulation in tumor cells as well as in stromal and immune cell subsets within the tumor microenvironment is hypothesized to represent an important resistance mechanism to current cancer immunotherapies. Soluble CD73 (sCD73) enzymatic activity measured in patient serum or plasma at a baseline is reported to have prognostic as well as predictive relevance, with higher sCD73 activity associating with poor overall and progression-free survival in melanoma patients undergoing anti-PD1 monoclonal antibody treatment. Here, we report a novel NMR-based method that measures the ex-vivo kinetics of sCD73 activity with high specificity and reproducibility and is suitable for future high-throughput implementation.

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A limitation to understanding drivers of long-term trends in terrestrial nitrogen (N) availability in forests and its subsequent influence on stream nitrate export is a general lack of integrated analyses using long-term data on terrestrial and aquatic N cycling at comparable spatial scales. Here we analyze relationships between stream nitrate concentrations and wood N records (n = 96 trees) across five neighboring headwater catchments in the Blue Ridge physiographic province and within a single catchment in the Appalachian Plateau physiographic province in the eastern United States. Climatic, acidic deposition, and forest disturbance datasets were developed to elucidate the influence of these factors on terrestrial N availability through time.

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Immunotherapy has fundamentally changed the landscape of cancer treatment. Despite the encouraging results with the checkpoint modulators, response rates vary widely across tumor types, with a majority of patients exhibiting either primary resistance without a significant initial response to treatment or acquired resistance with subsequent disease progression. Hematopoietic progenitor kinase 1 (HPK1) is predominantly expressed in hematopoietic cell linages and serves as a negative regulator in T cells and dendritic cells (DC).

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Little is known about the regional extent and variability of nitrate from atmospheric deposition that is transported to streams without biological processing in forests. We measured water chemistry and isotopic tracers (δO and δN) of nitrate sources across the Northern Forest Region of the U.S.

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The temporal dynamics of soil bacterial communities are understudied, but such understanding is critical to elucidating the drivers of community variation. The goal of this study was to characterize how soil bacterial communities vary across diurnal, sub-seasonal and seasonal time-scales in a 5.8 m2 plot and test the hypothesis that bacterial diversity varies on each of these scales.

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Paleoecological records suggest that growing season length and/or cloudiness may affect peatland carbon accumulation and testate amoeba-based environmental reconstructions, highlighting a need to understand how light intensity affects microbial communities. We shaded plots on two peatlands for two years to examine effects on testate amoeba communities, the relative abundance of mixotrophic and heterotrophic testate amoebae, transfer-function performance, and δC values of two species of mixotrophic testate amoebae. Surprisingly, relative abundance of mixotrophic species increased in shade, although compositional changes did not affect transfer-function performance.

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Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (δN) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar δN declined by 0.6-1.

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Rationale: Stable hydrogen isotope (δ H) ratios of animal tissues are useful for assessing movement and geographic origin of mobile organisms. However, it is uncertain whether heat and singeing affects feather δ H values and thus subsequent geographic assignments. This is relevant for birds of conservation interest that are burned and killed at concentrating solar-energy facilities that reflect sunlight to a receiving tower and generate a solar flux field.

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Bats perform important ecosystem services, but it remains difficult to quantify their dietary strategies and trophic position (TP) in situ. We conducted measurements of nitrogen isotopes of individual amino acids (δ N) and bulk-tissue carbon (δ C) and nitrogen (δ N) isotopes for nine bat species from different feeding guilds (nectarivory, frugivory, sanguivory, piscivory, carnivory, and insectivory). Our objective was to assess the precision of δ N-based estimates of TP relative to other approaches.

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Perturbation of organic anion transporter (OAT) 1- and OAT3-mediated transport can alter the exposure, efficacy, and safety of drugs. Although there have been reports of the endogenous biomarkers for OAT1/3, none of these have all of the characteristics required for a clinical useful biomarker. Cynomolgus monkeys were treated with intravenous probenecid (PROB) at a dose of 40 mg/kg in this study.

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