Chowdhury, P. R. | bioRxiv Science

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↗

bioRxiv2025

Co-isolation of genetically distinct Burkholderia pseudomallei strains from a single patient in North Queensland

While investigating colony morphology variation (CMV) within clinical isolates of Burkholderia pseudomallei (Bp) isolated from a single infection, we identified two distinct strains (based on their multi-locus sequence type) from Bp TSV292. Simultaneous co-infection is rare, previously reported in only 2 of 133 cases. Here, we present the first comprehensive multi-omics characterization of co-infecting Bp strains isolated from a single infection at a hospital in Townsville, Australia in 2018. This finding impacts the design of future diagnosis and treatment of Bp. ImportanceMelioidosis, a severe disease caused by the bacterium Burkholderia pseudomallei, is rarely caused by more than one strain at the same time. In this study, we examined two bacterial strains isolated at once from a patient treated for melioidosis at a hospital in northern Queensland (Australia). By comparing their genomes, proteins, and physical traits, we found important strain differences that may affect how they adapt and survive during infection. Considering strain diversity when studying how this pathogen causes disease is essential, as it directly impacts future diagnosis and treatment.

microbiology↗