Biology subjects

Arnold, K. A.

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

3 recordsLinked to original sources

bioRxiv2026

Fitness effects of copper selection in a wild-derived population of Drosophila melanogaster

Copper is an essential micronutrient in most organisms that becomes toxic in large quantities. Repeated or prolonged sub-lethal exposure can lead to evolved resistance to copper toxicity over many generations, which may result in trade-offs between energetically expensive detoxification mechanisms and fitness. Alternatively, evolved resistance to chemical stressors may lead to correlated changes in other traits. This study focuses on a population of flies for which artificial selection for copper resistance led to an increase in both copper resistance and longevity. The apparent off-target benefit of copper selection on one component of fitness led us to investigate differences in fecundity and developmental viability in copper resistant and copper sensitive, non-selected populations. We assessed the effect of copper selection and copper exposure on multiple aspects of fecundity over the lifespans of females from the non-selected and copper-selected populations. Our study corroborated previously observed increased longevity in copper-selected flies. Controlling for variation in lifespan, copper-resistant females had comparable age-matched fecundity to copper-sensitive females and benefitted from increased longevity with higher lifetime fecundity. Overall, copper exposure negatively affected egg quality, but we found no difference in this trait between the copper-resistant and sensitive populations. Further, we found developmental viability under copper stress was significantly higher for eggs laid by copper-resistant females. Overall, we determined that copper resistant flies experienced a fitness benefit through both lifespan and fecundity. Costs of maintaining copper resistance may be associated with energetic costs, but these trade-offs may not always manifest in reproductive or lifespan fitness costs.

evolutionary biology↗

bioRxiv2025

Artificial selection for resistance to copper and off-target physiological and behavioral effects in Drosophila melanogaster

Pollution resulting from mining, industry, and agriculture has played an important role in shaping the evolution of diverse organisms. The pathway to evolved resistance can involve polygenic shifts that affect multiple traits. Heavy metal contamination is of particular concern due to the health effects for humans and cross-tolerance effects that influence pesticide resistance. We used a replicated artificial selection approach to examine the response to copper selection in Drosophila melanogaster collected from a retired mine and active fruit orchard. We tracked shifts in resistance to the target trait, copper, as well as off-target effects on cadmium and lead resistance, starvation resistance, lifespan, and feeding aversion to copper contaminated food. Selection for copper resistance increased the focal trait and maintained resistance to non-essential heavy metals while control flies lost metal resistance overtime, implying a cost associated with maintaining resistance to heavy metals. Starvation resistance was correlated with copper resistance, but the correlation was not sufficient to explain the gain in copper resistance. Lifespan was correlated with increased copper resistance in flies collected from one of the two collection sites, suggesting that life history traits may be influenced by repeated heavy metal exposure. Future genomic analysis will help clarify the genetic control of the selection response. Together, our results underscore the complexity of adaptive shift in polygenic traits and provide a basis for further exploration of costs and correlative change following copper selection.

evolutionary biology↗

bioRxiv2018

Monocyte and Macrophage Subtypes as Paired Cell Biomarkers for Coronary Artery Disease

Background: Monocytes and macrophages are central to atherosclerosis, but how they mark progression of human coronary artery disease (CAD) is unclear. We tested whether patients monocyte subtypes paired with their derived macrophage profiles correlate with extent of CAD.\n\nMethods: Peripheral blood was collected from 30 patients undergoing cardiac catheterization, and patients were categorized as having no significant CAD, single vessel disease, or multivessel disease according to the number of affected coronary arteries. Mononuclear cells were measured for monocyte markers CD14 and CD16 by flow cytometry, and separate monocytes were cultured into macrophages over 7 days and measured for polarization markers CD86 and CD206.\n\nResults: At baseline, patients with greater CAD burden were older with higher rates of statin use, whereas all other characteristics were similar across the spectrum of coronary disease. Non-classical (CD14loCD16hi) and all CD16+ monocytes were elevated in patients with single vessel and multivessel disease compared to those without significant CAD (8.6% and 10.5% vs. 2.8%, p < 0.05), whereas regulatory M2 macrophages (CD206+) were decreased in patients with single vessel and multivessel disease (0.34% and 0.34% vs. 1.4%, p < 0.05). An inverse relationship between paired CD16+ monocytes and M2 macrophages marked CAD severity. CAD was also found to be more tightly associated with CD16+ cells than age or traditional cardiovascular risk factors on multiple regression analysis of these patients.\n\nConclusions: CAD extent is correlated directly with CD16+ monocytes and inversely with M2 (CD206+) macrophages, suggesting circulating monocytes may influence downstream polarization of lesional macrophages. These measures of monocyte and macrophage subtypes hold potential as biomarkers in CAD.

physiology↗