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Xie F, Yuan Q, Meng Y, Luan F. Degradation of methylmercury into Hg(0) by the oxidation of iron(II) minerals. WATER RESEARCH 2024; 256:121645. [PMID: 38653093 DOI: 10.1016/j.watres.2024.121645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 03/25/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Mercury contamination is a global concern, and the degradation and detoxification of methylmercury have gained significant attention due to its neurotoxicity and biomagnification within the food chain. However, the currently known pathways of abiotic demethylation are limited to light-induced photodegradation process and little is known about light-independent abiotic demethylation of methylmercury. In this study, we reported a novel abiotic pathway for the degradation of methylmercury through the oxidation of both mineral structural iron(II) and surface-adsorbed iron(II) in the absence of light. Our findings reveal that methylmercury can be oxidatively degraded by reactive oxygen species, specifically hydroxyl and superoxide radicals, which are generated from the oxidation of iron(II) minerals under dark conditions. Surprisingly, Hg(0) trapping experiments demonstrated that inorganic Hg(II) resulting from the oxidative degradation of methylmercury was rapidly reduced to gaseous Hg(0) by iron(II) minerals. The demethylation of methylmercury, coupled with the generation of Hg(0), suggests a potential natural attenuation process for methylmercury. Our results highlight the underappreciated roles of iron(II) minerals in the abiotic degradation of methylmercury and the release of gaseous Hg(0) into the atmosphere.
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Affiliation(s)
- Fuyu Xie
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Qingke Yuan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Ying Meng
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
| | - Fubo Luan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
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2
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Li MR, Men SH, Wang ZY, Liu C, Zhou GR, Yan ZG. The application of human-derived cell lines in neurotoxicity studies of environmental pollutants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168839. [PMID: 38036138 DOI: 10.1016/j.scitotenv.2023.168839] [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: 09/27/2023] [Revised: 11/17/2023] [Accepted: 11/22/2023] [Indexed: 12/02/2023]
Abstract
As industrial and societal advancements progress, an increasing number of environmental pollutants linked to human existence have been substantiated to elicit neurotoxicity and developmental neural toxicity. For research in this field, human-derived neural cell lines have become excellent in vitro models. This study examines the utilization of immortalized cell lines, specifically the SH-SY5Y human neuroblastoma cell line, and neural cells derived from human pluripotent stem cells, in the investigation of neurotoxicity and developmental neural toxicity caused by environmental pollutants. The study also explores the culturing techniques employed for these cell lines and provides an overview of the standardized assays used to assess various biological endpoints. The environmental pollutants involved include a variety of organic compounds, heavy metals, and microplastics. The utilization of cell lines derived from human sources holds significant significance in elucidating the neurotoxic effects of environmental pollutants and the underlying mechanisms. Finally, we propose the possibility of improving the in vitro model of the human nervous system and the toxicity detection methods.
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Affiliation(s)
- Ming-Rui Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Shu-Hui Men
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Zi-Ye Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Chen Liu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Guo-Rui Zhou
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Zhen-Guang Yan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
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3
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Li S, Li Z, Wu M, Zhou Y, Tang W, Zhong H. Mercury transformations in algae, plants, and animals: The occurrence, mechanisms, and gaps. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 911:168690. [PMID: 38000748 DOI: 10.1016/j.scitotenv.2023.168690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023]
Abstract
Mercury (Hg) is a global pollutant showing potent toxicity to living organisms. The transformations of Hg are critical to global Hg cycling and Hg exposure risks, considering Hg mobilities and toxicities vary depending on Hg speciation. Though currently well understood in ambient environments, Hg transformations are inadequately explored in non-microbial organisms. The primary drivers of in vivo Hg transformations are far from clear, and the impacts of these processes on global Hg cycling and Hg associated health risks are not well understood. This hinders a comprehensive understanding of global Hg cycling and the effective mitigation of Hg exposure risks. Here, we focused on Hg transformations in non-microbial organisms, particularly algae, plants, and animals. The process of Hg oxidation/reduction and methylation/demethylation in organisms were reviewed since these processes are the key transformations between the dominant Hg species, i.e., elemental Hg (Hg0), divalent inorganic Hg (IHgII), and methylmercury (MeHg). By summarizing the current knowledge of Hg transformations in organisms, we proposed the potential yet overlooked drivers of these processes, along with potential challenges that hinder a full understanding of in vivo Hg transformations. Knowledge summarized in this review would help achieve a comprehensive understanding of the fate and toxicity of Hg in organisms, providing a basis for predicting Hg cycles and mitigating human exposure.
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Affiliation(s)
- Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Zhuoran Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Mengjie Wu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
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4
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Zhang D, Xiang Y, Liu G, Liang L, Chen L, Shi J, Yin Y, Cai Y, Jiang G. Mechanism and controlling factors on rapid methylmercury degradation by ligand-enhanced Fenton-like reaction at circumneutral pH. CHEMOSPHERE 2023; 324:138291. [PMID: 36870614 DOI: 10.1016/j.chemosphere.2023.138291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/09/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Methylmercury (MeHg), derived from industrial processes and microbial methylation, is still a worldwide environmental concern. A rapid and efficient strategy is necessary for MeHg degradation in waste and environmental waters. Here, we provide a new method with ligand-enhanced Fenton-like reaction to rapidly degrade MeHg under neutral pH. Three common chelating ligands were selected (nitriloacetic acid (NTA), citrate, and ethylenediaminetetraacetic disodium (EDTA)) to promote the Fenton-like reaction and degradation of MeHg. Results showed that MeHg can be rapidly degraded, with the following efficiency sequence: EDTA > NTA > citrate. Scavenger addition demonstrated that hydroxyl radical (▪OH), superoxide radical (O2▪-), and ferryl (FeⅣO2+) were involved in MeHg degradation, and their relative contributions highly depended on ligand type. Degradation product and total Hg analysis suggested that Hg(Ⅱ) and Hg0 were generated with the demethylation of MeHg. Further, environmental factors, including initial pH, organic complexation (natural organic matter and cysteine), and inorganic ions (chloride and bicarbonate) on MeHg degradation, were investigated in NTA-enhanced system. Finally, rapid MeHg degradation was validated for MeHg-spiked waste and environmental waters. This study provided a simple and efficient strategy for MeHg remediation in contaminated waters, which is also helpful for understanding its degradation in the natural environment.
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Affiliation(s)
- Dingxi Zhang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Guangliang Liu
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, United States
| | - Lina Liang
- Beijing Zhongke PUYAN Science and Technology Co., Ltd, Beijing, 100096, China
| | - Lufeng Chen
- Institute of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Institute of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou, 310024, China.
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, United States
| | - 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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Zuo K, Xu Q, Wang Y, Sui Y, Niu Y, Liu Z, Liu M, Liu X, Liu D, Sun W, Wang Z, Liu X, Liu J. L-Ascorbic Acid 2-Phosphate Attenuates Methylmercury-Induced Apoptosis by Inhibiting Reactive Oxygen Species Accumulation and DNA Damage in Human SH-SY5Y Cells. TOXICS 2023; 11:144. [PMID: 36851019 PMCID: PMC9967424 DOI: 10.3390/toxics11020144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/28/2023] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Methylmercury (MeHg) is a toxin that causes severe neuronal oxidative damage. As vitamin C is an antioxidant well-known to protect neurons from oxidative damage, our goal was to elucidate its protective mechanism against MeHg-induced oxidative stress in human neuroblastomas (SHSY5Y). We treated cells with MeHg, L-ascorbic acid 2-phosphate (AA2P), or both, and used MTT, flow cytometry, and Western blot analyses to assess cell damage. We found that MeHg significantly decreased the survival rate of SH-SY5Y cells in a time- and dose-dependent manner, increased apoptosis, downregulated PAR and PARP1 expression, and upregulated AIF, Cyto C, and cleaved Caspase-3 expression. A time course study showed that MeHg increased reactive oxygen species (ROS) accumulation; enhanced apoptosis; increased DNA damage; upregulated expression ofγH2A.X, KU70, 67 and 57 kDa AIF, CytoC, and cleaved Caspase-3; and downregulated expression of 116 kDa PARP1, PAR, BRAC1, and Rad51. Supplementation with AA2P significantly increased cell viability and decreased intrinsic ROS accumulation. It also reduced ROS accumulation in cells treated with MeHg and decreased MeHg-induced apoptosis. Furthermore, AA2P conversely regulated gene expression compared to MeHg. Collectively, we demonstrate that AA2P attenuates MeHg-induced apoptosis by alleviating ROS-mediated DNA damage and is a potential treatment for MeHg neurotoxicity.
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Affiliation(s)
- Kuiyang Zuo
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Qi Xu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Yujie Wang
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Yutong Sui
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Ye Niu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Zinan Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Mingsheng Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Xinpeng Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Dan Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Wei Sun
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Ziyu Wang
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Xiaomei Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
| | - Jinyu Liu
- Department of Toxicology, School of Public Health, Jilin University, 1163 Xinmin Avenue, Changchun 130021, China
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6
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Li ML, Kwon SY, Poulin BA, Tsui MTK, Motta LC, Cho M. Internal Dynamics and Metabolism of Mercury in Biota: A Review of Insights from Mercury Stable Isotopes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:9182-9195. [PMID: 35723432 PMCID: PMC9261262 DOI: 10.1021/acs.est.1c08631] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Monitoring mercury (Hg) levels in biota is considered an important objective for the effectiveness evaluation of the Minamata Convention. While many studies have characterized Hg levels in organisms at multiple spatiotemporal scales, concentration analyses alone often cannot provide sufficient information on the Hg exposure sources and internal processes occurring within biota. Here, we review the decadal scientific progress of using Hg isotopes to understand internal processes that modify the speciation, transport, and fate of Hg within biota. Mercury stable isotopes have emerged as a powerful tool for assessing Hg sources and biogeochemical processes in natural environments. A better understanding of the tissue location and internal mechanisms leading to Hg isotope change is key to assessing its use for biomonitoring. We synthesize the current understanding and uncertainties of internal processes leading to Hg isotope fractionation in a variety of biota, in a sequence of better to less studied organisms (i.e., birds, marine mammals, humans, fish, plankton, and invertebrates). This review discusses the opportunities and challenges of using certain forms of biota for Hg source monitoring and the need to further elucidate the physiological mechanisms that control the accumulation, distribution, and toxicity of Hg in biota by coupling new techniques with Hg stable isotopes.
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Affiliation(s)
- Mi-Ling Li
- School
of Marine Science and Policy, University
of Delaware, 201 Robinson Hall, Newark, Delaware 19716, United
States
| | - Sae Yun Kwon
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
- Institute
for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea
| | - Brett A. Poulin
- Department
of Environmental Toxicology, University
of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Martin Tsz-Ki Tsui
- School
of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR 999077, China
| | - Laura C. Motta
- Department
of Chemistry, University at Buffalo, 359 Natural Sciences Complex, Buffalo, New York 14260-3000, United States
| | - Moonkyoung Cho
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
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7
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Ferroptosis as a mechanism of non-ferrous metal toxicity. Arch Toxicol 2022; 96:2391-2417. [PMID: 35727353 DOI: 10.1007/s00204-022-03317-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/11/2022] [Indexed: 11/02/2022]
Abstract
Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.
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8
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Fu X, Yang X, Du X, Cui Q. Deciphering the possible role of H2O2 in methylmercury-induced neurotoxicity in Xenopus laevis. Mol Cell Toxicol 2020. [DOI: 10.1007/s13273-020-00082-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Abstract
Backgrounds
Methylmercury (MeHg) is regarded as a developmental neurotoxicant but the detailed mechanism remains not completely clear.
Methods
The Xenopus laevis embryos were exposed to methylmercury chloride and the expression of neurodevelopment and oxidative stress genes was detected by qRT-PCR or Western blotting. PC12 cells were exposed to various levels of H2O2, and then cell cycle, neurite length, neurodevelopment-related genes, protein expression of apoptosis and autophagy were detected.
Results
The genes of neurodevelopment and oxidative stress were disrupted by methylmercury chloride and H2O2 were increased interestingly in X. laevis embryos. Then, PC12 cells were exposed to H2O2 and the results showed the cell cycle, neurite length, and neurodevelopment-related genes, the proteins apoptosis and autophagy were changed.
Conclusion
These results supported the idea that neurodevelopment-related gene expression was regulated by oxidative stress and that apoptosis and autophagy pathways were activated by H2O2 and involved in methylmercury neurotoxicity.
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9
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Ehnert-Russo SL, Gelsleichter J. Mercury Accumulation and Effects in the Brain of the Atlantic Sharpnose Shark (Rhizoprionodon terraenovae). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2020; 78:267-283. [PMID: 31760438 DOI: 10.1007/s00244-019-00691-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
Few published studies have examined whether the elevated concentrations of the nonessential toxic metal mercury (Hg) often observed in shark muscle also occur in the shark brain or whether Hg accumulation affects shark neurophysiology. Therefore, this study examined accumulation and distribution of Hg in the shark brain, as well as effects of Hg on oxidative stress in the shark central nervous system, with particular focus on the Atlantic sharpnose shark (Rhizoprionodon terraenovae). Sharks were collected along the southeastern U.S. coast throughout most of this species' U.S. geographical range. Total Hg (THg) concentrations were measured in and compared between shark muscle and brain, whereas known biomarkers of Hg-induced neurological effects, including glutathione depletion, lipid peroxidation, and concentrations of a protein marker of glial cell damage (S100b), were measured in shark cerebrospinal fluid. Brain THg concentrations were correlated with muscle THg levels but were significantly lower and did not exceed most published thresholds for neurological effects, suggesting limited potential for detrimental responses. Biomarker concentrations supported this premise, because these data were not correlated with brain THg levels. Hg speciation also was examined. Unlike muscle, methylmercury (MeHg) did not comprise a high percentage of THg in the brain, suggesting that differential uptake or loss of organic and inorganic Hg and/or demethylation of MeHg may occur in this organ. Although Hg accumulation in the shark brain generally fell below toxicity thresholds, higher THg levels were measured in the shark forebrain compared with the midbrain and hindbrain. Therefore, there is potential for selective effects on certain aspects of shark neurophysiology if brain Hg accumulation is increased.
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Affiliation(s)
- S L Ehnert-Russo
- University of North Florida, 1 UNF Dr, Jacksonville, FL, 32224, USA
| | - J Gelsleichter
- University of North Florida, 1 UNF Dr, Jacksonville, FL, 32224, USA.
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Krishna Chandran AM, Christina H, Das S, Mumbrekar KD, Satish Rao BS. Neuroprotective role of naringenin against methylmercury induced cognitive impairment and mitochondrial damage in a mouse model. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 71:103224. [PMID: 31376681 DOI: 10.1016/j.etap.2019.103224] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/09/2019] [Accepted: 07/21/2019] [Indexed: 06/10/2023]
Abstract
Human exposure to organomercurials like methylmercury (MeHg) may occur by consumption of contaminated seafood, affecting various vital organs especially, brain contributing to neuro disorders. The citrus flavanone, naringenin (NAR) has shown strong antioxidant and anti-inflammatory effects and therefore may exert cytoprotective effect against xenobiotic agents. Herein, we investigated the neuroprotective role of NAR against MeHg induced functional changes in mitochondria, neuronal cell death and cognitive impairment in a mouse model. A neurotoxic dose of MeHg (4 mg/kg.b.wt.) was administered orally to mice for 15 days. This resulted in the reduction of GSH and GST, an increase in mitochondrial DNA damage and memory impairment. On the contrary, NAR pre-treatment (100 mg/kg.b.wt.), helped in lowering the oxidative burden which in turn maintained mitochondrial function and prevented induced neuronal cell death, ultimately improving the cognitive impairment. As MeHg intoxication occurs chronically, consumption of the dietary components rich in NAR may have its positive human health impact, ultimately improving the quality of life.
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Affiliation(s)
- Adwaid Manu Krishna Chandran
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576 104, Karnataka, India
| | - Hannah Christina
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576 104, Karnataka, India
| | - Shubhankar Das
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576 104, Karnataka, India
| | - Kamalesh D Mumbrekar
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576 104, Karnataka, India
| | - B S Satish Rao
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576 104, Karnataka, India.
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11
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Chan MC, Bautista E, Alvarado-Cruz I, Quintanilla-Vega B, Segovia J. Inorganic mercury prevents the differentiation of SH-SY5Y cells: Amyloid precursor protein, microtubule associated proteins and ROS as potential targets. J Trace Elem Med Biol 2017; 41:119-128. [PMID: 28209268 DOI: 10.1016/j.jtemb.2017.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 01/16/2017] [Accepted: 02/05/2017] [Indexed: 10/20/2022]
Abstract
Exposure to mercury (Hg) occurs through different pathways and forms including methylmecury (MeHg) from seafood and rice, ethylmercury (EtHg), and elemental Hg (Hg0) from dental amalgams and artisanal gold mining. Once in the brain all these forms are transformed to inorganic Hg (I-Hg), where it bioaccumulates and remains for long periods. Hg is a well-known neurotoxicant, with its most damaging effects reported during brain development, when cellular key events, such as cell differentiation take place. A considerable number of studies report an impairment of neuronal differentiation due to MeHg exposure, however the effects of I-Hg, an important form of Hg found in brain, have received less attention. In this study, we decided to examine the effects of I-Hg exposure (5, 10 and 20μM) on the differentiation of SH-SY5Y cells induced by retinoic acid (RA, 10μM). We observed extension of neuritic processes and increased expression of neuronal markers (MAP2, tubulin-βIII, and Tau) after RA stimulation, all these effects were decreased by the co-exposure to I-Hg. Interestingly, I-Hg increased the levels of reactive oxygen species (ROS) and nitric oxide (NO) accompanied with increased levels of inducible nitric oxide synthase (iNOS) and, dimethylarginine dimethylaminohydrolase 1 (DDHA1). Remarkably I-Hg decreased levels of nitric oxide synthase neuronal (nNOS). Moreover I-Hg reduced the levels of tyrosine hydroxylase (TH) and amyloid precursor protein (APP) a protein recently involved in neuronal differentiation. These data suggest that the exposure to I-Hg impairs cell differentiation, and point to new potential targets of Hg toxicity such as APP and NO signaling.
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Affiliation(s)
- Miguel Chin Chan
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico; Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Campeche, Campeche 4039, Mexico
| | - Elizabeth Bautista
- Departmento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico; Facultad de Ciencias de la Salud, Universidad Anáhuac Norte, 52786, Huixquilucan, Mexico
| | - Isabel Alvarado-Cruz
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico
| | - Betzabet Quintanilla-Vega
- Departmento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico
| | - José Segovia
- Departmento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, 07360, Mexico.
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Durand N, Storz P. Targeting reactive oxygen species in development and progression of pancreatic cancer. Expert Rev Anticancer Ther 2016; 17:19-31. [PMID: 27841037 DOI: 10.1080/14737140.2017.1261017] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
INTRODUCTION Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.
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Affiliation(s)
- Nisha Durand
- a Department of Cancer Biology , Mayo Clinic , Jacksonville , FL , USA
| | - Peter Storz
- a Department of Cancer Biology , Mayo Clinic , Jacksonville , FL , USA
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Methylmercury alters glutathione homeostasis by inhibiting glutaredoxin 1 and enhancing glutathione biosynthesis in cultured human astrocytoma cells. Toxicol Lett 2016; 256:1-10. [PMID: 27180086 DOI: 10.1016/j.toxlet.2016.05.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 04/28/2016] [Accepted: 05/11/2016] [Indexed: 02/08/2023]
Abstract
Methylmercury (MeHg) is a neurotoxin that binds strongly to thiol residues on protein and low molecular weight molecules like reduced glutathione (GSH). The mechanism of its effects on GSH homeostasis particularly at environmentally relevant low doses is not fully known. We hypothesized that exposure to MeHg would lead to a depletion of reduced glutathione (GSH) and an accumulation of glutathione disulfide (GSSG) leading to alterations in S-glutathionylation of proteins. Our results showed exposure to low concentrations of MeHg (1μM) did not significantly alter GSH levels but increased GSSG levels by ∼12-fold. This effect was associated with a significant increase in total cellular glutathione content and a decrease in GSH/GSSG. Immunoblot analyses revealed that proteins involved in glutathione synthesis were upregulated accounting for the increase in cellular glutathione. This was associated an increase in cellular Nrf2 protein levels which is required to induce the expression of antioxidant genes in response to cellular stress. Intriguingly, we noted that a key enzyme involved in reversing protein S-glutathionylation and maintaining glutathione homeostasis, glutaredoxin-1 (Grx1), was inhibited by ∼50%. MeHg treatment also increased the S-glutathionylation of a high molecular weight protein. This observation is consistent with the inhibition of Grx1 and elevated H2O2 production however; contrary to our original hypothesis we found few S-glutathionylated proteins in the astrocytoma cells. Collectively, MeHg affects multiple arms of glutathione homeostasis ranging from pool management to protein S-glutathionylation and Grx1 activity.
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Mailloux RJ, Yumvihoze E, Chan HM. Superoxide produced in the matrix of mitochondria enhances methylmercury toxicity in human neuroblastoma cells. Toxicol Appl Pharmacol 2015; 289:371-80. [DOI: 10.1016/j.taap.2015.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/28/2015] [Accepted: 11/02/2015] [Indexed: 01/08/2023]
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