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BMC Pharmacology & Toxicology Dec 2019Exposure to vinylcyclohexene (VCH) and methylmercury (MeHg) can induce oxidative stress and gene modulation. Several studies have been evaluating the effects of VCH and...
BACKGROUND
Exposure to vinylcyclohexene (VCH) and methylmercury (MeHg) can induce oxidative stress and gene modulation. Several studies have been evaluating the effects of VCH and MeHg, but little is known about interactive effects between them. This work aimed to assess the exposure and co-exposure effects of MeHg and VCH on oxidative stress and gene modulation in Drosophila melanogaster.
METHODS
Reactive species production, glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities were evaluated after exposure and co-exposure to VCH (1 mM) and MeHg (0.2 mM) for one or three days in the head and body (thorax and abdomen) of flies. The expression of genes related to redox state and inflammatory response was evaluated after exposure and co-exposure to VCH and MeHg for three days.
RESULTS
Survival decreased only in flies co-exposed to VCH and MeHg for three days. All treatments increased total reactive species production after one day of exposure. However, no significant changes were observed in the head after three days of exposure. One day of exposure to VCH caused an increase in the head GST activity, whereas MeHg induced an increase after three days of exposure. Regarding the body, all treatments increased GST activity after one day of exposure, but only the flies exposed to MeHg presented an increase in GST activity after three days of exposure. Treatments did not alter AChE activity in the head. As for gene expression, there was a significant increase in the Relish transcription factor gene in the flies' body, but Nrf2, Keap1, Jafrac1, TrxR1, and NF-κβ were not altered.
CONCLUSION
The results suggest that exposure to VCH and MeHg induce oxidative stress and activation of an inflammatory response in fruit flies.
Topics: Acetylcholinesterase; Animals; Cyclohexenes; Dose-Response Relationship, Drug; Drosophila Proteins; Drosophila melanogaster; Drug Synergism; Gene Expression; Glutathione Transferase; Methylmercury Compounds; Oxidative Stress
PubMed: 31852533
DOI: 10.1186/s40360-019-0356-0 -
Environmental Pollution (Barking, Essex... May 2022Carbamazepine (CBZ) and Hg are widespread and persistent micropollutants in aquatic environments. Both pollutants are known to trigger similar toxicity mechanisms, e.g....
Carbamazepine (CBZ) and Hg are widespread and persistent micropollutants in aquatic environments. Both pollutants are known to trigger similar toxicity mechanisms, e.g. reactive oxygen species (ROS) production. Here, their effects were assessed in the zebra mussel Dreissena polymorpha, frequently used as a freshwater model in ecotoxicology and biomonitoring. Single and co-exposures to CBZ (3.9 μg L) and MeHg (280 ng L) were performed for 1 and 7 days. Metabolomics analyses evidenced that the co-exposure was the most disturbing after 7 days, reducing the amount of 25 metabolites involved in protein synthesis, energy metabolism, antioxidant response and osmoregulation, and significantly altering cells and organelles' structure supporting a reduction of functions of gills and digestive glands. CBZ alone after 7 days decreased the amount of α-aminobutyric acid and had a moderate effect on the structure of mitochondria in digestive glands. MeHg alone had no effect on mussels' metabolome, but caused a significant alteration of cells and organelles' structure in gills and digestive glands. Single exposures and the co-exposure increased antioxidant responses vs control in gills and digestive glands, without resulting in lipid peroxidation, suggesting an increased ROS production caused by both pollutants. Data globally supported that a higher number of hyperactive cells compensated cellular alterations in the digestive gland of mussels exposed to CBZ or MeHg alone, while CBZ + MeHg co-exposure overwhelmed this compensation after 7 days. Those effects were unpredictable based on cellular responses to CBZ and MeHg alone, highlighting the need to consider molecular toxicity pathways for a better anticipation of effects of pollutants in biota in complex environmental conditions.
Topics: Animals; Carbamazepine; Dreissena; Gills; Methylmercury Compounds; Water Pollutants, Chemical
PubMed: 35122922
DOI: 10.1016/j.envpol.2022.118933 -
Environmental Science and Pollution... Apr 2023The past decade witnessed the initiation and boom of the Artisanal and Small-scale Gold Mining (ASGM) activities in the hyper-arid southern Egypt. The ores are mined in...
The past decade witnessed the initiation and boom of the Artisanal and Small-scale Gold Mining (ASGM) activities in the hyper-arid southern Egypt. The ores are mined in the Eastern Desert and then transported to the densely populated farming communities in the Nile Valley, where the river provides the water resources needed for ore processing. In search for economic benefits, the poorly educated farmers with limited technical resources transformed their cultivated lands into ASGM operations, exposing themselves, their families, the residents, and the Nile ecosystems to several environmental and occupational health problems. Using integrated remote sensing, field, geochemical, and isotopic analyses, we report the first inventory of ASGM-related total mercury (THg) and methylmercury (MeHg) levels in tailings, amalgamation-tailing ponds, and surface and groundwater with emphasis on the Edfu city and its surroundings. The field and remote sensing-based mapping of ASGM activities reveals clustering around the Nile waterways and suggests interaction of Hg contamination sources with their surrounding receptors. Common ASGM practices include release of contaminated water from unlined amalgamation-tailing ponds into irrigation and drainage canals, and spreading of tailings over cultivated soils. In a short period (10 years), the released Hg contaminated multiple media, including the surface water, the shallow and deep aquifers, and possibly the soil, crops, and livestock. THg levels in amalgamation-tailing ponds (1200-8470 ng/L) are fourfold higher than US EPA and eightfold the WHO thresholds. The contaminated waters released from amalgamation-tailing ponds raised THg levels in surface water (irrigation canals: 50-100 ng/L; drainage canals: THg: > 200 ng/L) and groundwater (shallow and deep aquifers: 80-500 ng/L). Our findings highlight the need to extend the adopted approach to cover the entire length of the Nile River and its valley and the importance of conducting awareness campaigns to educate residents and health care providers about potential ASGM-related environmental and health hazards.
Topics: Humans; Mercury; Methylmercury Compounds; Ecosystem; Environmental Monitoring; Gold; Egypt; Soil; Mining; Water
PubMed: 36829096
DOI: 10.1007/s11356-023-25895-9 -
International Journal of Environmental... Jan 2020Gintonin is a newly discovered ingredient of ginseng and plays an exogenous ligand for G protein-coupled lysophosphatidic acid receptors. We previously showed that...
Gintonin is a newly discovered ingredient of ginseng and plays an exogenous ligand for G protein-coupled lysophosphatidic acid receptors. We previously showed that gintonin exhibits diverse effects from neurotransmitter release to improvement of Alzheimer's disease-related cognitive dysfunctions. However, previous studies did not show whether gintonin has protective effects against environmental heavy metal. We investigated the effects of gintonin-enriched fraction (GEF) on methylmercury (MeHg)-induced neurotoxicity and learning and memory dysfunction and on organ MeHg elimination. Using hippocampal neural progenitor cells (hNPCs) and mice we examined the effects of GEF on MeHg-induced hippocampal NPC neurotoxicity, on formation of reactive oxygen species (ROS), and on in vivo learning and memory functions after acute MeHg exposure. Treatment of GEF to hNPCs attenuated MeHg-induced neurotoxicity with concentration- and time-dependent manner. GEF treatment inhibited MeHg- and ROS inducer-induced ROS formations. Long-term treatment of GEF also improved MeHg-induced learning and memory dysfunctions. Oral administration of GEF decreased the concentrations of MeHg in blood, brain, liver, and kidney. This is the first report that GEF attenuated MeHg-induced in vitro and in vivo neurotoxicities through LPA (lysophosphatidic acids) receptor-independent manner and increased organ MeHg elimination. GEF-mediated neuroprotection might achieve via inhibition of ROS formation and facilitation of MeHg elimination from body.
Topics: Animals; Cognitive Dysfunction; Female; Methylmercury Compounds; Mice; Mice, Inbred C57BL; Panax; Plant Extracts; Receptors, Lysophosphatidic Acid
PubMed: 32013120
DOI: 10.3390/ijerph17030838 -
Ecotoxicology and Environmental Safety Feb 2023Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and... (Review)
Review
Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.
Topics: Humans; Mercury; Methylmercury Compounds; Soil; Oryza; Agriculture; Soil Pollutants
PubMed: 36628877
DOI: 10.1016/j.ecoenv.2023.114516 -
Environmental Research Mar 2021Biogeochemical conditions and landscape can have strong influences on mercury bioaccumulation in fish, but these effects across regional scales and between sites with...
Biogeochemical conditions and landscape can have strong influences on mercury bioaccumulation in fish, but these effects across regional scales and between sites with and without point sources of contamination are not well understood. Normal means clustering, a type of unsupervised machine learning, was used to analyze relationships between forage fish (Fundulus heteroclitus and Menidia menidia) mercury (Hg) concentrations and sediment and water column Hg and methylmercury (MeHg) concentrations, ancillary variables, and land classifications within the sub-watershed. The analysis utilized data from 38 sites in 8 estuarine systems in the Northeast US, collected over five years. A large range of mercury concentrations and land use proportions were observed across sites. The cluster correlations indicated that for Fundulus, benthic and pelagic Hg and MeHg concentrations were most related to tissue concentrations, while Menidia Hg was most related to water column MeHg, reflecting differing feeding modes between the species. For both species, dissolved MeHg was most related to tissue concentrations, with sediment Hg concentrations influential at contaminated sites. The models considering only uncontaminated sites showed reduced influence of bulk sediment MeHg for both species, but Fundulus retained sediment drivers at some sites, with dissolved MeHg still highly correlated for both. Dissolved organic carbon (DOC), chlorophyll, land use, and other ancillary variables were of lesser importance in driving bioaccumulation, though DOC was strongly related within some clusters, likely in relation to dissolved Hg. Land use, though not of primary importance, showed relationships opposite to those observed in freshwater, with development positively correlated and forests and agriculture negatively correlated with tissue concentrations across clusters and species. Clusters were composed of sites from geographically distinct systems, indicating the greater importance of small scale drivers of MeHg formation and uptake into the food web over system or region-wide influences.
Topics: Animals; Environmental Monitoring; Estuaries; Fishes; Food Chain; Mercury; Methylmercury Compounds; Water Pollutants, Chemical
PubMed: 33358725
DOI: 10.1016/j.envres.2020.110629 -
Ecotoxicology and Environmental Safety Nov 2023Methylmercury is a neurotoxic compound that can enter rice fields through rainfall or irrigation with contaminated wastewater, and then contaminate the human food chain...
Methylmercury is a neurotoxic compound that can enter rice fields through rainfall or irrigation with contaminated wastewater, and then contaminate the human food chain through the consumption of rice. Flooded paddy soil has a porous structure that facilitates air exchange with the atmosphere, but the presence of trace amounts of oxygen in flooded rice field soil and its impact on microbial-mediated formation of methylmercury is still unclear. We compared the microbial communities and their functions in oxygen-depleted and oxygen-limited paddy soil. We discovered that oxygen-limited paddy soil had higher methylmercury concentration, which was strongly correlated with soil properties and methylation potential. Compared with oxygen-depleted soil, oxygen-limited soil altered the microbial composition based on 16 S rRNA sequences, but not based on hgcA sequences. Moreover, oxygen-limited soil enhanced microbial activity significantly, increasing the abundance of more than half of the KEGG pathways, especially the metabolic pathways that might be involved in methylation. Our study unveils how microbial communities influence methylmercury formation in oxygen-limited paddy soil. ENVIRONMENTAL IMPLICATIONS: This study examined how low oxygen input affects microbial-induced MeHg formation in anaerobic paddy soil. We found that oxygen-limited soil produced more MeHg than oxygen-depleted soil. Oxygen input altered the microbial community structure of 16 S rRNA sequencing in anaerobic paddy soil, but had little impact on the hgcA sequencing community structure. Microbial activity and metabolic functions related to MeHg formation were also higher in oxygen-limited paddy soil. We suggest that oxygen may not be a limiting factor for Hg methylators, and that insufficient oxygen input in flooded paddy soil increases the risk of human exposure to MeHg from rice consumption.
Topics: Humans; Methylmercury Compounds; Soil; Oxygen; Soil Pollutants; Mercury; Microbiota; Oryza
PubMed: 37856980
DOI: 10.1016/j.ecoenv.2023.115585 -
Neurotoxicology Jul 2023Current guidelines for developmental neurotoxicity (DNT) evaluation are based on animal models. These have limitations so more relevant, efficient and robust approaches...
Current guidelines for developmental neurotoxicity (DNT) evaluation are based on animal models. These have limitations so more relevant, efficient and robust approaches for DNT assessment are needed. We have used the human SH-SY5Y neuroblastoma cell model to evaluate a panel of 93 mRNA markers that are frequent in Neuronal diseases and functional annotations and also differentially expressed during retinoic acid-induced differentiation in the cell model. Rotenone, valproic acid (VPA), acrylamide (ACR) and methylmercury chloride (MeHg) were used as DNT positive compounds. Tolbutamide, D-mannitol and clofibrate were used as DNT negative compounds. To determine concentrations for exposure for gene expression analysis, we developed a pipeline for neurite outgrowth assessment by live-cell imaging. In addition, cell viability was measured by the resazurin assay. Gene expression was analyzed by RT-qPCR after 6 days of exposure during differentiation to concentrations of the DNT positive compounds that affected neurite outgrowth, but with no or minimal effect on cell viability. Methylmercury affected cell viability at lower concentrations than neurite outgrowth, hence the cells were exposed with the highest non-cytotoxic concentration. Rotenone (7.3 nM) induced 32 differentially expressed genes (DEGs), ACR (70 µM) 8 DEGs, and VPA (75 µM) 16 DEGs. No individual genes were significantly dysregulated by all 3 DNT positive compounds (p < 0.05), but 9 genes were differentially expressed by 2 of them. Methylmercury (0.8 nM) was used to validate the 9 DEGs. The expression of SEMA5A (encoding semaphorin 5A) and CHRNA7 (encoding nicotinic acetylcholine receptor subunit α7) was downregulated by all 4 DNT positive compounds. None of the DNT negative compounds dysregulated any of the 9 DEGs in common for the DNT positive compounds. We suggest that SEMA5A or CHRNA7 should be further evaluated as biomarkers for DNT studies in vitro since they also are involved in neurodevelopmental adverse outcomes in humans.
Topics: Animals; Humans; Methylmercury Compounds; Rotenone; RNA, Messenger; Neuroblastoma; Neurons; Neurotoxicity Syndromes; Cell Differentiation
PubMed: 37210002
DOI: 10.1016/j.neuro.2023.05.011 -
Environmental Science & Technology Mar 2021Mercury (Hg) is a toxic trace element of global environmental concern which has been increasingly dispersed into the environment since the industrial revolution. In...
Mercury (Hg) is a toxic trace element of global environmental concern which has been increasingly dispersed into the environment since the industrial revolution. In aquatic and terrestrial systems, Hg can be reduced to elemental Hg (Hg) and escape to the atmosphere or converted to methylmercury (MeHg), a potent neurotoxin that accumulates in food webs. Fe-bearing minerals such as magnetite, green rusts, siderite, and mackinawite are recognized Hg reducers. Another potentially Hg-reducing mineral, which commonly occurs in Fe- and organic/P-rich sediments and soils, is the ferrous iron phosphate mineral vivianite (Fe(PO)·8HO), but its reaction with Hg has not been studied to date. Here, nanoparticulate vivianite (particle size ∼ 50 nm; Fe content > 98%) was chemically synthesized and characterized by a combination of chemical, spectroscopic, and microscopic analyses. Its ability to reduce Hg was investigated at circumneutral pH under anoxic conditions over a range of Fe/Hg ratios (0.1-1000). For Fe/Hg ratios ≥1, which are representative of natural environments, Hg was very quickly and efficiently reduced to Hg. The ability of vivianite to reduce Hg was found to be similar to those of carbonate green rust and siderite, two of the most effective Hg-reducing minerals. Our results suggest that vivianite may be involved in abiotic Hg reduction in Fe and organic/P-rich soils and sediments, potentially contributing to Hg evasion while also limiting MeHg formation in these ecosystems.
Topics: Ecosystem; Ferrous Compounds; Mercury; Oxidation-Reduction; Phosphates
PubMed: 33554594
DOI: 10.1021/acs.est.0c05203 -
Properties influencing flux and diatom uptake of mercury and methylmercury from estuarine sediments.Environmental Pollution (Barking, Essex... Apr 2024Mercury (Hg) is a conspicuous and persistent global pollutant. Ionic Hg can be methylated into noxious methylmercury (CHHg), which biomagnifies in marine tropic webs and...
Mercury (Hg) is a conspicuous and persistent global pollutant. Ionic Hg can be methylated into noxious methylmercury (CHHg), which biomagnifies in marine tropic webs and poses a health risk to humans and organisms. Sediment Hg methylation rates are variable, and the output flux of created CHHg are dependent on sediment characteristics and environmental factors. Thus, uncertainties remain about the formation and flux of CHHg from sediment, and how this could contribute to the bioaccumulative burden for coastal organisms in shallow ecosystems. Cores were collected from 3 estuarine locations along the Eastern USA to examine how sediments characteristics influence the introduction of Hg and CHHg into the base of the food chain. Stable isotopes of inorganic Hg and CHHg were injected into sediments of individual cores, with cultured diatoms constrained to overlying waters. Five different treatments were done on duplicate cores, spiked with: (1) no Hg isotopes (control); (2) inorganic Hg; (3) CHHg; (4) both Hg and CHHg isotopes, (5) both Hg and CHHg into overlying waters (not sediment). Experimental cores were incubated for 3 days under temperature and light controlled conditions. These results demonstrate that upper sediments characteristics lead to high variability in Hg cycling. Notably, sediments which contained abundant and peaty organic material (∼28 %LOI), had the highest pore water DOC (3206 μM) and displayed bands of sulfur reducing bacteria yielded the greatest methylation rate (1.97 % day) and subsequent diatom uptake of CHHg (cell quota 0.18 amol/cell) in the overlying water.
Topics: Humans; Mercury; Methylmercury Compounds; Diatoms; Ecosystem; Water Pollutants, Chemical; Geologic Sediments; Isotopes; Water; Environmental Monitoring
PubMed: 38423275
DOI: 10.1016/j.envpol.2024.123604