Bioaccumulation of manganese and its effects on oxidative stress and immune response in juvenile groupers (Epinephelus moara ♀ × E. lanceolatus ♂)

Integrating reverse osmosis to a conventional river water treatment plant as a strategy to produce drinking water after mining dam rupture events: a case study

Incidents of mining dam failure have compromised the water quality, threatening the water supply. Different strategies are sought to restore the impacted area and to guarantee the water supply. One example is water treatment plants that treat high-polluted waters within the required limits for their multiple usages. The current study assesses the integration of reverse osmosis (RO) to a river water treatment plant (RWTP) installed in Brumadinho (Minas Gerais, Brazil) to treat the water from the Ferro-Carvão stream impacted by the B1 dam rupture in 2019. The RWTP started eleven months after the mining dam rupture and is equipped with eight coagulation-flocculation tanks followed by eight pressurised filters. A pilot RO plant was installed to polish the water treated by the RWTP. Water samples were collected at different points of the water treatment plant and were characterised by their physical, chemical, and biological parameters (160 in total). The results were compared with the historical data (1997-2022) to reveal the alterations in the water quality after the rupture event. The compliance with both parameters was only achieved after the RO treatment, which acted as an additional barrier to 30 contaminants. The water quality indexes (WQI) suggested that the raw surface water, even eleven months after the incident, was unfit for consumption (WQI: 133.9) whereas the reverse osmosis permeate was ranked as excellent in the rating grid (WQI: 23.7).

Identification of histone acetylation modification sites in the striatum of subchronically manganese-exposed rats

Aim: To explore the specific histone acetylation sites and oxidative stress-related genes that are associated with the pathogenesis of manganese toxicity. Methods: We employed liquid chromatography-tandem mass spectrometry and bioinformatics analysis to identify acetylated proteins in the striatum of subchronic manganese-intoxicated rats. Results: We identified a total of 12 differentially modified histone acetylation sites: H3K9ac, H3K14ac, H3K18ac, H3K56ac and H3K79ac were upregulated and H3K27ac, H3K36ac, H4K91ac, H4K79ac, H4K31ac, H2BK16ac and H2BK20ac were downregulated. Additionally, we found that CAT, SOD1 and SOD2 might be epigenetically regulated and involved in the pathogenesis of manganism. Conclusion: This study identified histone acetylation sites and oxidative stress-related genes associated with the pathogenesis of manganese toxicity, and these findings are useful in the search for potential epigenetic targets for manganese toxicity.

Investigation of oxidative stress status and apoptotic markers of juvenile trout exposed to arsenic toxicity

Arsenic is one of the most abundant elements on earth. Arsenic, also called metalloid, is used as a raw material in many industries. Arsenic causes the acceleration of free radical production in the body and the resulting oxidative stress. In juvenile trout, the interactions of arsenic with metacomposition, biochemical analysis, and apoptosis stimuli were investigated. Results were demonstrated by several marker applications, including oxidative stress parameters, proinflammatory cytokine expressions, DNA damage, and apoptosis markers. In our study, arsenic was applied to juvenile trout (Oncorhynchus mykiss) at concentrations of 25, 50, and 75 mg/L for 96 h. After exposure, the brain tissues of the fish were collected and homogenized. SOD the GSH-Px, CAT, and MDA levels were determined by spectrophotometric methods in the supernatants from the brain tissues of the juvenile trout. Levels of NF-kB, TNF-α, IL-6, Nrf-2, GSH, caspase-3, AChE, and 8-OHdG were determined with an ELISA kit. When the brain tissues of the fish were examined after the study, it was found that the levels of NF-kB, TNF-α, IL-6, Nrf-2, Caspza-3, MDA, and 8-OHdG increased, and the levels of GSH, CAT, SOD, AChE, and GSH-Px decreased. It was found that oxidative stress occurred as a result of the effect of the heavy metal arsenic in the brain tissues of the fish after application.

Independent and Combined Associations of Blood Manganese, Cadmium and Lead Exposures with the Systemic Immune-Inflammation Index in Adults

Manganese (Mn), cadmium (Cd) and lead (Pb) have toxic effects on the immune system. However, their independent and combined effects on immune-inflammation responses are unclear. In recent years, the systemic immune-inflammation index (SII) has been developed as an integrated and novel inflammatory indicator. A retrospective cross-sectional study of 2174 adults ≥20 years old from the National Health and Nutrition Examination Survey (NHANES) 2015-2016 was conducted. Generalized linear models were used to evaluate the independent and combined associations of SII with blood Mn, Cd and Pb levels. As continuous variables, both blood Cd and Mn showed dose-dependent relationships with the SII before and after adjusting for all potential confounding factors. Metal concentrations were then converted into categorical variables. Compared with the adults in the lowest Cd or Mn tertile, those in the highest tertile had higher risks of elevated SII. Furthermore, co-exposure to Mn and Cd also showed a positive relationship with the SII after adjusting for all confounding factors. However, the single effect of Pb exposure and the joint effect of Pb and other metal exposures on the SII were not observed. This study provides important epidemiological evidence of the associations of SII with single and co-exposure effects of blood Mn, Cd, and Pb.

Exposure to manganese (II) chloride induces developmental toxicity, oxidative stress and inflammatory response in Marine medaka (Oryzias melastigma) embryos

Manganese (Mn) is an essential metal for organisms, but high levels can induce serious toxicity. To date, the toxic mechanism of Mn to marine fish is still poorly understood. In the present study, Oryzias melastigma embryos were exposed to different concentrations of MnCl₂ (0-152.00 mg/L) to investigate its effect on early development. The results showed that exposure to MnCl₂ caused developmental toxicity to embryos, including increased heart rate, delayed hatching time, decreased hatching rate and increased malformation rate. MnCl₂ exposure could induce oxidative stress in O. melastigma embryos, as indicated by increased the contents of malondialdehyde (MDA) and the activities of the antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT)). The heart might be an important target organ for MnCl₂ because of cardiac malformations and disruption in the expression of cardiac development-related genes (ATPase, epo, fg8g, cox1, cox2, bmp4 and gata4). In addition, the expression levels of stress- (omTERT and p53) and inflammation-related genes (TNFα and il1β) were significantly up-regulated, suggesting that MnCl₂ can trigger stress and inflammatory response in O. melastigma embryos. In conclusion, this study demonstrated that MnCl₂ exposure can induce developmental toxicity, oxidative stress and inflammatory response in O. melastigma embryos, providing insights into the toxic mechanism of Mn to the early development of marine fish.

Multiple biomarkers response of Astyanax lacustris (Teleostei: Characidae) exposed to manganese and temperature increase

The present study aimed to evaluate the toxicity of Mn (6.65 mg/L) at different exposure times (96 h, 7, 14, and 21 days) and evaluate its possible toxic effects on the fish Astyanax lacustris through multi-biomarkers and the maximum critical temperature (CT Max). The results show an increase in the Mn accumulation (liver and gills) with increasing exposure time. The glutathione S-transferase (GST) activity showed differences in the group exposed to Mn for 96 h compared to the group exposed for 21 days. The acetylcholinesterase (AChE) activity increased in the fish exposed for 7 days compared to the control group. On the other hand, no genotoxic changes were observed. The CT Max showed that the loss of equilibrium of 50% of the fish occurs at a temperature of 39ºC, with and without the Mn presence. Furthermore, the catalase gene expression (oxidative stress) did not show alterations.

High water temperature-mediated immune gene expression of olive flounder, Paralichthys olivaceus according to pre-stimulation at high temperatures

Increased ocean temperature due to global warming affects the health and immunity of fish. In this study, juvenile Paralichthys olivaceus were exposed to high temperature after pre-heat (Acute: Acute heat shock at 32 °C, AH-S: Acquired heat shock at 28 °C & short recovery (2h) and heat shock at 32 °C, AH-L: acquired heat shock at 28 °C and long recovery (2 days), AH-LS: acquired heat shock at 28 °C & long (2 days) + short (2h) recovery). Heat shock after pre-heat significantly upregulated various immune-related genes, including interleukin 8 (IL-8), c-type lysozyme (c-lys), immunoglobulin M (IgM), Toll-like receptor 3 (tlr3), major histocompatibility complex IIα (mhcIIα) and cluster of differentiation 8α (cd8α) in the liver and brain of P. olivaceus. This study showed pre-exposure to high temperatures below the critical temperature can activate fish immunity and increase tolerance to high temperatures.

Sirt3-Sod2-mROS-Mediated Manganese Triggered Hepatic Mitochondrial Dysfunction and Lipotoxicity in a Freshwater Teleost

Exposure to excessive manganese (Mn) is toxic to humans and animals. However, the toxic effects and mechanisms of excessive Mn influencing the vertebrates have been highly overlooked. In the present study, dietary Mn overload significantly increased hepatic lipid and Mn contents, decreased superoxide dismutase 2 (Sod2) activity, increased the Sod2 acetylation level, and induced mitochondrial dysfunction; Mn induced mitochondrial dysfunction through Mtf1/sirtuin 3 (Sirt3)-mediated acetylation of Sod2 at the sites K55 and K70. Meanwhile, mitochondrial oxidative stress was involved in Mn-induced lipotoxicity. Mechanistically, Mn-induced lipotoxicity was via oxidative stress-induced Hsf1 nucleus translocation and its DNA binding capacity to the regions of a peroxisome proliferator-activated receptor g (pparg) promoter, which in turn induced the transcription of lipogenic-related target genes. For the first time, our study demonstrated that Mn-induced hepatic lipotoxicity via a mitochondrial oxidative stress-dependent Hsf1/Pparg pathway and Mtf1/sirt3-mediated Sod2 acetylation participated in mitochondrial dysfunction. Considering that lipid metabolism and lipotoxicity are widely used as the biomarkers for environmental assessments of pollutants, our study provided innovative and important insights into Mn toxicological and environmental evaluation in aquatic environments.