Synchrotron XRF and Histological Analyses Identify Damage to Digestive Tract of Uranium NP-Exposed Daphnia magna

• Published in: Environmental science & technology Vol. 57; no. 2; pp. 1071 - 1079
• Main Authors: Byrnes, Ian, Rossbach, Lisa Magdalena, Jaroszewicz, Jakub, Grolimund, Daniel, Ferreira Sanchez, Dario, Gomez-Gonzalez, Miguel A., Nuyts, Gert, Reinoso-Maset, Estela, Janssens, Koen, Salbu, Brit, Brede, Dag Anders, Lind, Ole Christian
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 17-01-2023
• Subjects: Animals; Computed tomography; Damage detection; Daphnia; Daphnia magna; Disruption; Ecotoxicology and Public Health; Epithelial cells; Epithelium; Exposure; Fluorescence; Gastrointestinal Tract; Intestine; Liver; Midgut; Mode of action; Morphology; Nanoparticles; Particulates; Synchrotrons; Toxicity; Uranium; Uranium - toxicity; Water Pollutants, Chemical - toxicity; X ray absorption; X ray fluorescence analysis; X-ray fluorescence; X-Rays; X-ray fluorescence; nanoparticles; toxicokinetics; X-ray absorption computed tomography; X-ray absorption spectroscopy; uranium; nanotoxicology
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/acs.est.2c07174

Micro- and nanoscopic X-ray techniques were used to investigate the relationship between uranium (U) tissue distributions and adverse effects to the digestive tract of aquatic model organism Daphnia magna following uranium nanoparticle (UNP) exposure. X-ray absorption computed tomography measurements of intact daphnids exposed to sublethal concentrations of UNPs or a U reference solution (URef) showed adverse morphological changes to the midgut and the hepatic ceca. Histological analyses of exposed organisms revealed a high proportion of abnormal and irregularly shaped intestinal epithelial cells. Disruption of the hepatic ceca and midgut epithelial tissues implied digestive functions and intestinal barriers were compromised. Synchrotron-based micro X-ray fluorescence (XRF) elemental mapping identified U co-localized with morphological changes, with substantial accumulation of U in the lumen as well as in the epithelial tissues. Utilizing high-resolution nano-XRF, 400–1000 nm sized U particulates could be identified throughout the midgut and within hepatic ceca cells, coinciding with tissue damages. The results highlight disruption of intestinal function as an important mode of action of acute U toxicity in D. magna and that midgut epithelial cells as well as the hepatic ceca are key target organs.