Biology subjects

Shaw, J. R.

Publications and source records attributed to Shaw, J. R..

6 recordsLinked to original sources

bioRxiv2026

Role of Nutritional Status on Arsenic Toxicity in Daphnia pulex: A Transcriptomic Perspective on Individual and Interactive Effects

Inorganic arsenic is a widespread environmental contaminant and known human carcinogen, yet the mechanisms by which nutritional status modulates arsenic toxicity remain poorly understood. Here, we investigated the main and interactive effects of environmentally relevant concentrations of arsenic, low food quantity, and low dietary phosphorus supply on genome-wide gene expression in aquatic grazer Daphnia pulex. Differential gene expression analysis identified a total of 1,213 differently expressed genes with interactions of arsenic x nutrient stressors accounting for approximately 70% of the transcriptomic response. Low phosphorus emerged as a dominant main effect stressor and it also had a profound impact on transcription as a co-stressor. The low phosphorus x arsenic interaction exhibited the greatest transcriptional impact (435 DE genes), revealing that phosphorus limitation rather than food quantity influences arsenic toxicity at the gene expression level. Gene ontology and Pathway Activation Analysis revealed that main effects elicited simple yet distinct functional responses, whereas arsenic x nutrient interactions induced complex pathway-level disruptions including cell signaling, detoxification metabolism, DNA repair mechanisms, and energy homeostasis. Further assessment of gene expression revealed that all arsenic x nutrient interactions are antagonistic supporting previous literature that found arsenic behaves antagonistically as a co-stressor. Our results provide mechanistic insight into how nutritional status modulates arsenic toxicity and highlights the importance of considering arsenic x nutrient co-stressor interactions.

pharmacology and toxicology↗

bioRxiv2026

Conserved Molecular Responses to Arsenite Exposure in Drosophila melanogaster

Arsenic exposure is a pervasive global health threat strongly associated with increased risk of morbidities such as diabetes, cardiovascular disease, and cancer. Despite extensive studies describing the dangers of arsenic exposure, the molecular initiating events that link arsenic to chronic disease onset and progression remain poorly defined. To address this knowledge gap, we combined time-resolved transcriptomic and metabolomic profiling of adult Drosophila melanogaster exposed to sodium (meta) arsenite (NaAsO2). We uncovered coordinated, dose-dependent shifts in gene expression and metabolite abundance that activate canonical detoxification pathways and mirror arsenic-associated disease signatures in humans. Notably, flies rapidly upregulated heatshock and xenobiotic response gene networks, followed by biomarkers characteristic of diabetic states (elevated glucose, lactate, and methylglyoxal, for example). These findings reveal conserved molecular pathways that couple arsenic exposure to metabolic dysfunction and establish Drosophila as a powerful whole-organism model for identifying early biomarkers and mechanistic drivers of arsenic-induced disease phenotypes.

pharmacology and toxicology↗

bioRxiv2025

Discovery and evaluation of cadmium-adapted Daphnia pulex genotypes in a region of historical mining reveals adaptation protects the germline from cadmium-induced mutations

Exposure to chemical pollutants can alter the rate, and genome-wide distribution of germline mutations. However, studies measuring the effect of chemical exposure on mutation rate and spectra have not considered the ecological and evolutionary backgrounds of studied genotypes, which could influence the rates and patterns of germline mutations in altered environments, e.g., chemical pollution. Utilizing a study of natural Daphnia pulex populations, we conducted a comprehensive experiment to test our hypothesis that adaptation to chemical pollution also protects the germline from mutagenesis. We, 1) identified Daphnia pulex populations that have adapted to live in mining-devastated regions by increasing their cadmium tolerance. 2) We completed a mutation-accumulation (MA) experiment with an adapted genotype to measure the germline mutation rate in both control conditions and an environmentally relevant cadmium concentration. 3) We compared these MA experiment results to a previously reported, identically designed MA experiment with a nonadapted genotype. We report that patterns of cadmium-induced mutagenesis in the adapted genotype were reversed compared to our previous observations in the nonadapted genotype. Cadmium exposure altered the single nucleotide mutation (SNM) rate in the same genome regions in adapted and nonadapted genotypes, but the rates were changed in opposite directions. Cadmium also altered specific SNM classes in these genotypes in opposite directions. The reversal of mutational trends in the adapted genotype suggests protection against cadmium genotoxicity. We further demonstrate that adapted populations have elevated gene copy-number and expression levels of metallothionein, the protein that protects against cadmium toxicity by binding to cadmium irreversibly.

evolutionary biology↗

bioRxiv2024

Lipid Nanoparticles from L. meyenii Walp Mitigate Sepsis through Multimodal Protein Corona Formation

BackgroundPlant-derived nanoparticles (PDNP) are nano-sized particles isolated from various edible plants that contain bioactive components involved in regulating cellular immune responses against pathogenic intrusion and inflammation. PurposeThis study describes a novel PDNP derived from Lepidium meyenii Walp (maca) that efficiently captures pro-inflammatory cytokines and acute phase proteins in its protein corona to enhance survival in two representative lethal models of sepsis. MethodsLipid nanoparticles were isolated from maca (MDNP) and triacylglycerols and phytoceramides were identified as major constituents using lipidomics. The physicochemical properties of MDNPs were determined, anti-inflammatory effects of MDNP were evaluated using in vitro models and in vivo using endotoxemia and cecal ligation and puncture (CLP) polymicrobial sepsis models. Proteomic analysis of MDNP in healthy or LPS-induced inflammatory plasma was used to determine the composition and inflammatory pathways modulated due to the MDNP protein corona. ResultsIn vitro studies showed that MDNP were non-toxic, reduced macrophage activation, and effectively sequestered pro-inflammatory cytokines to mitigate NF-{kappa}B activity under lipopolysaccharide (LPS) stimulation. In a pre-established LPS-induced endotoxemia model, MDNP-treated mice showed significantly reduced systemic pro-inflammatory cytokines and enhanced survival. Untargeted proteomics and pathway analysis of the MDNP protein corona identified an enrichment in acute phase proteins in MDNP-LPS plasma coronas. MDNP treatment also significantly improved survival in the CLP sepsis model in the absence of antibiotics. ConclusionThis work identified MDNP as an efficient, plant-derived lipid NP that broadly sequesters and neutralizes a compilation of inflammatory mediators in their coronas, offering multimodal therapeutic potential for treating inflammatory diseases.

bioengineering↗

bioRxiv2023

A Pair of Cadmium-exposed Zebrafish Affect Boldness and Landmark use in the Un-exposed Majority

Some individuals have a disproportionate effect on group responses. These individuals may possess distinct attributes that differentiate them from others. These characteristics may include susceptibility to contaminant exposure such as cadmium, a potent trace metal present in water and food. Here, we tested whether a pair of cadmium-exposed individuals could exert an impact on the behavior of the unexposed majority. We used behavioral assessments to characterize the extent of the effects of the cadmium-exposed pair on group boldness, cohesion, activity and responses to landmarks. We found that groups with a pair of cadmium-exposed fish approached and remained closer to novel stimuli and landmarks than did groups with pairs of fish treated with uncontaminated water (control). Shoals with cadmium and water treated fish exhibited similar levels of cohesion and activity. The results suggest that fish acutely exposed to environmentally-relevant cadmium concentrations can have profound effects on the un-exposed majority.

animal behavior and cognition↗

bioRxiv2021

Chromosomal rearrangements preserve adaptive divergence in ecological speciation

Despite increasing empirical evidence that chromosomal rearrangements may play an important role in adaptive divergence and speciation, the degree to which divergent genomic regions are associated with chromosomal rearrangements remains unclear. In this study, we provide the first whole-genome analyses of ecological speciation and chromosomal evolution in a Daphnia species complex, using chromosome-scale assemblies and natural-population sequencing of the recently diverged species pair, Daphnia pulicaria and Daphnia pulex, which occupy distinct yet overlapping habitats in North America, and the outgroup species Daphnia obtusa. Our results describe a mixed mode of geographic divergence (isolation with secondary contact) resulting in a heterogeneous landscape of genomic divergence. Large contiguous "continents of divergence" encompass over one third of the genome (36%) and contain nearly all the fixed differences (94%) between the species, while the background genome has been homogenized. Chromosomal rearrangements between species, including inversions and intrachromosomal translocations, are associated with the continents of divergence and capture multiple adaptive alleles in genes and pathways thought to contribute to the species phenotypic differences.

evolutionary biology↗