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Ibrahim M, Belden JB, Minghetti M. Interactive Effects of Copper-Silver Mixtures at the Intestinal Epithelium of Rainbow Trout: An In Vitro Approach. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024; 43:105-114. [PMID: 37818877 DOI: 10.1002/etc.5762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/17/2023] [Accepted: 10/08/2023] [Indexed: 10/13/2023]
Abstract
While metals are present in mixture in the environment, metal toxicity studies are usually conducted on an individual metal basis. There is a paucity of data in the existing literature regarding specific metal-metal interactions and their effect on metal toxicity and bioavailability. We studied interactions of a silver (Ag)-copper (Cu) mixture at the intestinal epithelium using an intestinal cell line derived from rainbow trout (Oncorhynchus mykiss), the RTgutGC. Exposures were conducted in media containing different chloride concentrations (low chloride, 1 mM; high chloride, 146 mM), thus resulting in different metal speciation. Cytotoxicity was evaluated based on two endpoints, cell metabolic activity and cell membrane integrity. The Ag-Cu mixture toxicity was assessed using two designs: independent action and concentration addition. Metal mixture bioavailability was studied by exposing cells to 500 nM of Ag or Cu as a single metal or a mixture (i.e., 500 nM of Cu plus 500 nM of Ag). We found an antagonistic effect in the low-chloride medium and an additive/synergistic effect in the high-chloride medium. We found that Cu dominates over Ag toxicity and bioavailability, indicating a competitive inhibition when both metals are present as free metal ions in the exposure media, which supports our hypothesis. Our study also suggests different mechanisms of uptake of free metal ions and metal complexes. The study adds valuable information to our understanding of the role of metal speciation on metal mixture toxicity and bioavailability. Environ Toxicol Chem 2024;43:105-114. © 2023 SETAC.
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Affiliation(s)
- Md Ibrahim
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
- Charles River Laboratories, Ashland, Ohio, USA
| | - Jason B Belden
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Matteo Minghetti
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
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Oldham D, Black T, Stewart TJ, Minghetti M. Role of the luminal composition on intestinal metal toxicity, bioavailability and bioreactivity: An in vitro approach based on the cell line RTgutGC. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 256:106411. [PMID: 36716651 DOI: 10.1016/j.aquatox.2023.106411] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 01/07/2023] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
The bioavailability of metal complexes is poorly understood. To evaluate bioavailability and toxicity of neutral and charged complexes as well as free metal ions, Visual Minteq, a chemical equilibrium model, was used to design media containing different metal species. Two non-essential (silver and cadmium) and two essential (copper and zinc) metals were selected. The rainbow trout (Oncorhynchus mykiss) gut cell line (RTgutGC) was used to investigate bioavailability, bioreactivity and toxicity of the different metal species. Toxicity was measured using a multiple endpoint cytotoxicity assay, bioavailability by measuring intracellular metal concentration, and bioreactivity by quantification of mRNA level of the metal responsive genes, metallothionein (MT), glutathione reductase (GR) and zinc transporter 1 (ZnT1). Speciation calculations showed that silver and cadmium preferentially bind chloride, copper phosphate and bicarbonate, and zinc remained primarily as a free ion. Cysteine avidly complexed with all metals reducing toxicity, bioavailability and bioreactivity. Silver and copper toxicity was not affected by inorganic metal speciation, whereas cadmium and zinc toxicity was decreased by chloride complexation. Moreover, reduction of calcium concentration in the medium increased toxicity and bioavailability of cadmium and zinc. Bioavailability of silver and zinc was reduced by low chloride while cadmium bioavailability was increased by low chloride and in presence of bicarbonate. Copper bioavailability was not affected by the medium composition. Cadmium and silver were more bioreactive, independently from the medium composition, in comparison to copper and zinc (i.e., higher induction of MT and GR). Cadmium was the only metal able to induce MT in presence of cysteine. ZnT1 was induced by cadmium in low-chloride, by zinc in low-chloride low-calcium and by cadmium and copper in the bicarbonate media. Overall, this study demonstrates that metal complexation alone is not sufficient to explain metal toxicity, and that anion exchange mechanisms play a role in metal uptake and bioreactivity.
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Affiliation(s)
- Dean Oldham
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - Thomas Black
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - Theodora J Stewart
- Research Management & Innovation Directorate, Kings College London, London, UK
| | - Matteo Minghetti
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA.
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Ibrahim M, Minghetti M. Effect of chloride concentration on the cytotoxicity, bioavailability, and bioreactivity of copper and silver in the rainbow trout gut cell line, RTgutGC. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:626-636. [PMID: 35362806 DOI: 10.1007/s10646-022-02543-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Chloride (Cl-) influences the bioavailability and toxicity of metals in fish, but the mechanisms by which it influences these processes is poorly understood. Here, we investigated the effect of chloride on the cytotoxicity, bioavailability (i.e., accumulation) and bioreactivity (i.e., induction of mRNA levels of metal responsive genes) of copper (Cu) and silver (Ag) in the rainbow trout gut cell line (RTgutGC). Cells were exposed to metals in media with varying Cl- concentrations (0, 1, 5 and 146 mM). Metal speciation in exposure medium was analyzed using Visual MINTEQ software. Cytotoxicity of AgNO3 and CuSO4 was measured based on two endpoints: metabolic activity and membrane integrity. Cells were exposed to 500 nM of AgNO3 and CuSO4 for 24 h in respective media to determine metal bioavailability and bioreactivity. Ag speciation changes from free ionic (Ag+) to neutral (AgCl), to negatively charged chloride complexes (AgCl2-, AgCl3-) with increasing Cl- concentration in exposure media whereas Cu speciation remains in two forms (Cu2+ and CuHPO4) across all media. Chloride does not affect Ag bioavailability but decreases metal toxicity and bioreactivity. Cells exposed to Ag expressed significantly higher metallothionein mRNA levels in low Cl- media (0, 1, and 5 mM) than in high Cl- medium (146 mM). This suggests that chloride complexation reduces silver bioreactivity and toxicity. Conversely, Cu bioavailability and toxicity were higher in the high chloride medium (146 mM) than in the low Cl- (0, 1, and 5 mM) media, supporting the hypothesis that Cu uptake may occur via a chloride dependent mechanism. CLINICAL TRIALS REGISTRATION: This study did not require clinical trial registration.
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Affiliation(s)
- Md Ibrahim
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA.
| | - Matteo Minghetti
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
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Ibrahim M, Oldham D, Minghetti M. Role of metal speciation in the exposure medium on the toxicity, bioavailability and bio-reactivity of copper, silver, cadmium and zinc in the rainbow trout gut cell line (RTgutGC). Comp Biochem Physiol C Toxicol Pharmacol 2020; 236:108816. [PMID: 32502601 DOI: 10.1016/j.cbpc.2020.108816] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 05/24/2020] [Accepted: 05/29/2020] [Indexed: 12/15/2022]
Abstract
The role of metal speciation on metal bioavailability, bio-reactivity and toxicity at the fish intestine is poorly understood. To investigate these processes, we used an in vitro model of the rainbow trout (Oncorhynchus mykiss) intestine, the RTgutGC cell line. Cells were exposed to two essential metals (copper and zinc) and two non-essential metals (cadmium and silver) in a medium of well-defined composition, which allowed the determination of metal speciation in solution. Concentrations resulting in a 50% cell viability reduction (EC50) were measured using a viability assay based on two endpoints: metabolic activity and membrane integrity. Metal bioavailability and bio-reactivity was studied at non-toxic (300 nM all metals) and toxic (EC10; Ag-0.6, Cu-0.9, Cd-3, and Zn-9 μM) concentrations. Bioavailability (i.e. intracellular metal accumulation) was determined by ICP-MS, while bio-reactivity (i.e. induction of a metal specific transcriptional response) was determined by measuring the mRNA levels of a known biomarker of metal exposure (i.e. metallothionein) and of copper and zinc transporters (i.e. ATP7A and ZnT1). Dominant metal species in the exposure medium were Zn2+, CuHPO4, CdCl+, and AgCl2- respectively for Zn, Cu, Cd, and Ag. The EC50s showed the metal toxicity hierarchy: Ag > Cu > Cd > Zn. In RTgutGC cells, essential metal homeostasis was tightly regulated while non-essential metals accumulated more readily. Non-essential metals were also more bio-reactive inducing higher MT and ZnT1 mRNA levels. Taken together these findings indicate that metal toxicity in RTgutGC cannot solely be explained by extracellular metal speciation but requires the evaluation of metal bioavailability and bio-reactivity.
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Affiliation(s)
- Md Ibrahim
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - Dean Oldham
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - Matteo Minghetti
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA.
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Yang Q, Shan W, Hu L, Zhao Y, Hou Y, Yin Y, Liang Y, Wang F, Cai Y, Liu J, Jiang G. Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:625-633. [PMID: 30525513 DOI: 10.1021/acs.est.8b02471] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag+ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag+ ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl- ions, HS(Cl)) and Hogland solutions (without Cl- ions, HS) using dual stable isotope tracing (107AgNO3 and 109AgNPs). After coexposure to 107Ag+ ions and 109AgNPs at 50 μg L-1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag+ ions (from 107Ag+ ions and 109AgNPs) were retained on the root surface, while the occurrence of AgNPs (from 109AgNPs and 107Ag+ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag+ ions. Higher fractions of Ag+ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag+ ions and AgNPs and the role of AgNPs as carriers and sources of Ag+ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.
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Affiliation(s)
- Qingqing Yang
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China
| | - Wanyu Shan
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
| | - Ligang Hu
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China
| | - Yao Zhao
- Beijing National Laboratory for Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yinzhu Hou
- Beijing National Laboratory for Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yongguang Yin
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China
| | - Yong Liang
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
| | - Fuyi Wang
- Beijing National Laboratory for Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yong Cai
- Institute of Environment and Health, Jianghan University , Wuhan 430056 , China
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Jingfu Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China
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Lourenço J, Marques S, Carvalho FP, Oliveira J, Malta M, Santos M, Gonçalves F, Pereira R, Mendo S. Uranium mining wastes: The use of the Fish Embryo Acute Toxicity Test (FET) test to evaluate toxicity and risk of environmental discharge. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 605-606:391-404. [PMID: 28672228 DOI: 10.1016/j.scitotenv.2017.06.125] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 06/15/2017] [Accepted: 06/15/2017] [Indexed: 05/28/2023]
Abstract
Active and abandoned uranium mining sites often create environmentally problematic situations, since they cause the contamination of all environmental matrices (air, soil and water) with stable metals and radionuclides. Due to their cytotoxic, genotoxic and teratogenic properties, the exposure to these contaminants may cause several harmful effects in living organisms. The Fish Embryo Acute Toxicity Test (FET) test was employed to evaluate the genotoxic and teratogenic potential of mine liquid effluents and sludge elutriates from a deactivated uranium mine. The aims were: a) to determine the risk of discharge of such wastes in the environment; b) the effectiveness of the chemical treatment applied to the uranium mine water, which is a standard procedure generally applied to liquid effluents from uranium mines and mills, to reduce its toxicological potential; c) the suitability of the FET test for the evaluation the toxicity of such wastes and the added value of including the evaluation of genotoxicity. Results showed that through the FET test it was possible to determine that both elutriates and effluents are genotoxic and also that the mine effluent is teratogenic at low concentrations. Additionally, liquid effluents and sludge elutriates affect other parameters namely, growth and hatching and that water pH alone played an important role in the hatching process. The inclusion of genotoxicity evaluation in the FET test was crucial to prevent the underestimation of the risks posed by some of the tested effluents/elutriates. Finally, it was possible to conclude that care should be taken when using benchmark values calculated for specific stressors to evaluate the risk posed by uranium mining wastes to freshwater ecosystems, due to their chemical complexity.
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Affiliation(s)
- J Lourenço
- Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - S Marques
- Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - F P Carvalho
- Instituto Superior Técnico/Laboratório de Proteccão e Segurança Radiológica, Universidade de Lisboa, Estrada Nacional 10, km 139, 2695-066 Bobadela LRS, Portugal.
| | - J Oliveira
- Instituto Superior Técnico/Laboratório de Proteccão e Segurança Radiológica, Universidade de Lisboa, Estrada Nacional 10, km 139, 2695-066 Bobadela LRS, Portugal.
| | - M Malta
- Instituto Superior Técnico/Laboratório de Proteccão e Segurança Radiológica, Universidade de Lisboa, Estrada Nacional 10, km 139, 2695-066 Bobadela LRS, Portugal.
| | - M Santos
- Instituto Superior Técnico/Laboratório de Proteccão e Segurança Radiológica, Universidade de Lisboa, Estrada Nacional 10, km 139, 2695-066 Bobadela LRS, Portugal.
| | - F Gonçalves
- Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - R Pereira
- Department of Biology, Faculty of Sciences of the University of Porto & CIIMAR - Interdisciplinary Centre of Marine and Environmental Research & GreenUP/CITAB-UP, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
| | - S Mendo
- Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
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