Synchrotron XRF Analysis Identifies Cerium AccumulationColocalized with Pharyngeal Deformities in CeO2NP-ExposedCaenorhabditis elegans

A combination of synchrotron radiation-based elementalimaging, in vivo redox status analysis, histology, and toxic responses was usedto investigate the uptake, biodistribution, and adverse effects of Cenanoparticles (CeO2NP; 10 nm; 0.5-34.96 mg Ce L-1) or Ce(NO3)3(2.3-26 mg Ce L-1)inCaenorhabditis elegans. Elemental mapping of theexposed nematodes revealed Ce uptake in the alimentary canal prior todepuration. Retention of CeO2NPs was low compared to that of Ce(NO3)3in depurated individuals. X-rayfluorescence (XRF) mapping showed that Cetranslocation was confined to the pharyngeal valve and foregut. Ce(NO3)3exposure significantly decreased growth, fertility, and reproduction, causedslightly reduced fecundity. XRF mapping and histological analysis revealedsevere tissue deformities colocalized with retained Ce surrounding thepharyngeal valve. Both forms of Ce activated the sod-1 antioxidant defense,particularly in the pharynx, whereas no significant effects on the cellular redox balance were identified. The CeO2NP-induceddeformities did not appear to impair the pharyngeal function or feeding ability as growth effects were restricted to Ce(NO3)3exposure. The results demonstrate the utility of integrated submicron-resolution SR-based XRF elemental mapping of tissue-specificdistribution and adverse effect analysis to obtain robust toxicological evaluations of metal-containing contaminants.

Automated summary

A combination of techniques was used to study the uptake, biodistribution, and adverse effects of Ce nanoparticles and Ce(NO3)3 in Caenorhabditis elegans. The results showed that Ce uptake occurred in the alimentary canal and translocation was confined to specific regions. Ce(NO3)3 exposure caused significant effects on growth, fertility, and reproduction, while CeO2NP-induced deformities did not impair feeding ability. The study highlights the importance of sub-micron resolution SR-based XRF elemental mapping for robust toxicological evaluation.