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A Method to Preserve Wetland Roots and Rhizospheres for Elemental Imaging
Published on: February 15, 2021
Subcellular distribution of trace elements including rare earth elements in native and caged Dreissena polymorpha in
Audrey Catteau1, Marie Lefranc2, Jean Prygiel3
1Université de Reims Champagne-Ardenne (URCA), UMR I-02 Stress Environnementaux et BIOsurveillance des milieux aquatiques, Reims, France.
Abstract:
The exposure history of aquatic organisms can strongly influence the subcellular partitioning of trace elements (TEs) and, consequently, their toxic potential. However, subcellular TE distribution has rarely been compared between chronically exposed native organisms and caged individuals used in active biomonitoring frameworks. Following improvements to subcellular partitioning protocols, the subcellular distribution of four metals (Zn, Cd, Pb, Tl) and four rare earth elements (REEs; Ce, Nd, Pr, Sm) was determined in gills and digestive glands of both caged and native populations of zebra mussels (Dreissena polymorpha), a widely used biomonitoring species. The study was conducted on the historically contaminated Deûle River (France), an ecosystem impacted by TE contamination from various local sources. Results revealed subcellular metal-handling strategies differed not only among elements but also across organs and exposure conditions. Cd detoxification appeared more effective in the gills of caged mussels (31%) than in native mussels (20%), suggesting that granule activation occurs predominantly in newly exposed organisms. All four REEs displayed consistent subcellular distribution across organs and exposure conditions. However, they were preferentially associated with the metal-sensitive compartment (including mitochondria, microsomes/lysosomes, heat-denatured proteins) in digestive glands of native mussels (from 60% to 70%) relative to caged ones (from 48% to 55%), indicating higher susceptibility to REE (Class A) contamination than for other TEs (Class B/Borderline). Detoxification of REEs was mainly associated with granules, while other TEs relied on both heat-stable proteins (including metallothioneins) and granules. These findings enhance our understanding of intracellular metal management strategies and provide key information for toxicokinetic modelling, supporting improved risk assessments of emerging contaminants.
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