Toxicity of representative mixture of five rare earth elements in juvenile rainbow trout (Oncorhynchus mykiss) juveniles

Abstract

Rare earth elements (REEs) are contaminants of increasing interest due to intense mining activities for commercial purposes and ultimately released in the environment. We exposed juvenile rainbow trout (Oncorhynchus mykiss) to a representative mixture of the five most abundant REEs for 96 h at concentrations similar found in lakes contaminated by mining activities at 0.1, 1, 10, and 100X whereas the 1x mixture contained cerium (Ce, 280 μg/L), lanthanum (La, 140 μg/L), neodymium (Nd, 120 μg/L), praseodymium (Pr, 28 μg/L), and samarium (Sm, 23 μg/L). We investigated the expression of 14 genes involved in oxidative stress, DNA repair, tissue growth/proliferation, protein chaperoning, xenobiotic biotransformation, and ammonia metabolism in the liver. In addition, DNA damage, oxidative stress (lipid peroxidation or LPO), inflammation (cyclooxygenase or COX activity), detoxification mechanisms (glutathione-S-transferase activity or GST), and labile zinc were determined in gills. The data revealed that genes involved in oxidative stress-catalase (cat), heat shock proteins 70 (hsp70), and glutamate dehydrogenase (glud) were upregulated while glutathione S-transferase (gst) and metallothionein (mt) gene expressions were downregulated. The mixture was genotoxic and increased labile Zn in gills of exposed trout. These changes occurred at concentrations 600 times lower than the LC50 for this mixture indicating effects below the 1X concentration. Based on principal component analysis and concentration-dependent reponses, the following sublethal effects were considered the most important/significant: DNA strand breaks (genotoxicity), labile Zn, cat, gst, hsp70, sparc, mt, and glud. These effects of fish juveniles are likely to occur in environments under the influence of mining activities.

Toxicity of lanthanides on various fish cell lines

“…In environmental toxicology, to predict and understand the biological responses induced by the effects of mixtures (i.e., synergism, additivivity or antagonism) is one of the greatest challenges, and at the same time an essential aspect of ecotoxicological risk assessment (Norwood et al, 2003). To date, few studies were carried out to assess the impacts of Lanthanide mixtures using various organisms such bacteria, algae, rotifers, daphnids, ostracods, and fish (Hao et al, 1997;Tai et al, 2010;Tan et al, 2017;Blinova et al, 2018;Romero et al, 2019;Hanana et al, 2021). In these studies, different mixture toxicities were observed, according to Lanthanide compositions.…”

“…The current literature on the ecotoxicity of Lanthanides is mostly confined to Lanthanum, Cerium, and Gadolinium, and studies of Lanthanide mixtures remain limited (Herrmann et al, 2016;Romero et al, 2019;Hanana et al, 2021). Until now, the question of a common toxicity profile for Lanthanides is not solved, some authors agree with this assumption (Blinova et al, 2018) while others mentioned a toxicity related to the atomic number (Manusadzianas et al, 2020).…”

Therapeutic Intervention with Dietary Chitosan Nanoparticles Alleviates Fish Pathological and Molecular Systemic Inflammatory Responses against Infections

“…CFX Maestro Software (Bio-Rad Laboratories Inc., Munich, Germany) was used for the expressions’ normalization assessment. The performance of the RT-qPCR analysis for each gene was controlled using duplicate template and duplicate transcriptase controls [ 52 , 53 ].…”