Metallothionein Levels Research Articles

Accumulation, biochemical responses and changes in the redox proteome promoted by Ag and Cd in the burrowing bivalve Scrobicularia plana

Silver (Ag) and cadmium (Cd) are non-essential metals that, as a result of natural processes and human activities, reach the aquatic environment where they interact with biota inducing potential toxic effects. To determine the biological effects of these metals on the endobenthic bivalve Scrobicularia plana, specimens were exposed to Ag and Cd at two concentrations, 5 and 50 μg∙L-1, for 7 days in a controlled microcosm system. The levels of the metals were measured in the seawater, sediments and clam tissues. The possible toxic biological effects of Ag and Cd were studied using a battery of biochemical biomarkers that are responsive to oxidative stress: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) activities, and metallothioneins (MTs) and lipid peroxidation (LPO) levels. Since both metals have been linked to oxidative stress, redox modifications to proteins were studied by differential isotopic labelling of the oxidised and reduced forms of cysteines (Cys). An accumulation of metals was observed in the digestive gland and gills following exposure, together with the activation of enzyme activities (SOD for the Cd exposure; SOD, CAT, GST, and GR for the Ag exposure). The MT and LPO levels (after individual exposure to Ag and Cd) increased, which suggests the existence of antioxidant and detoxification processes to mitigate the toxic oxidative effects of both metals. The redox proteomic analysis identified 771 Cys-containing peptides (out of 514 proteins), of which 195 and 226 changed after exposure to Ag and Cd, respectively. Bioinformatics analysis showed that exposure to metal affects relevant functional pathways and biological processes in S. plana, such as: “cellular respiration” (Ag), “metabolism of amino acids” and “synthesis and degradation of proteins” (Ag and Cd), “carbohydrate metabolism” and “oxidative stress” (Cd). The proteomic approach implemented here is a powerful complement to conventional biochemical biomarkers, since it evaluates changes at the protein level in a high-throughput unbiased manner, thus providing a general appraisal of the biological responses altered by exposure to the contaminants.

Multi-omic analysis of Huntington’s disease reveals a compensatory astrocyte state

The mechanisms underlying the selective regional vulnerability to neurodegeneration in Huntington’s disease (HD) have not been fully defined. To explore the role of astrocytes in this phenomenon, we used single-nucleus and bulk RNAseq, lipidomics, HTT gene CAG repeat-length measurements, and multiplexed immunofluorescence on HD and control post-mortem brains. We identified genes that correlated with CAG repeat length, which were enriched in astrocyte genes, and lipidomic signatures that implicated poly-unsaturated fatty acids in sensitizing neurons to cell death. Because astrocytes play essential roles in lipid metabolism, we explored the heterogeneity of astrocytic states in both protoplasmic and fibrous-like (CD44+) astrocytes. Significantly, one protoplasmic astrocyte state showed high levels of metallothioneins and was correlated with the selective vulnerability of distinct striatal neuronal populations. When modeled in vitro, this state improved the viability of HD-patient-derived spiny projection neurons. Our findings uncover key roles of astrocytic states in protecting against neurodegeneration in HD.

Investigation of the Relationship Between Heavy Metals (Cadmium, Arsenic, and Lead) and Metallothionein in Multiple Sclerosis.

Multiple sclerosis (MS) is one of the most common neurological disorders. Metals are important for the maintenance and preservation of homeostasis and dysregulated metal homeostasis has an impact on neurodegeneration. Environmental factors are considered to contribute to MS risk and progression. Heavy metals such as arsenic (As), cadmium (Cd), and lead (Pb) are widely found in the environment and because of their toxic nature, they pose a great danger to human health. Metallothioneins (MTs) play important roles in metal homeostasis and detoxification of heavy metals. The aim of this study was to investigate the relationship between levels of heavy metals (As, Cd, and Pb) andMT levels in MS patients and also to assess the oxidative stress status of patients. Fifty subjects (20 healthy subjects and 30 MS patients) were included. Demographic characteristics of the patients, plasma MT levels, blood Cd, As, and Pb levels, as well as iron (Fe), copper (Cu), and zinc (Zn) levels, were determined. Malondialdehyde (MDA) levels were investigated as a marker of oxidative stress. MT levels were slightly higher in the MS group (p > 0.05). As Cd and Pb levels were significantly higher in the control subjects. MDA levels were significantly higher in MS patients. Our results support the relevance of MT and MDA levels in MS. Further clinical studies with larger cohorts will provide more insights into these factors.

Long-term cadmium stress influenced the immune response of Pardosa pseudoannulata by modulating its gut microbiota and hemolymph metabolome

Cadmium (Cd) is a common environmental heavy metal pollutant known for its toxic effects on various plants and animals. Cd contamination also poses a threat to Pardosa pseudoannulata, a predator in rice paddies. Results indicate that Cd pollution significantly reduced the levels of Metallothionein, phenoloxidase, and Ca2+. Furthermore, through metabolomics and 16S rDNA sequencing, alterations in the gut microbiota and immune-related metabolites of P. pseudoannulata were identified. The abundance of harmful bacteria such as Staphylococcus increased significantly, while levels of l-Tyrosine, glutathione disulfide, l-Dopa, among others, decreased markedly. Pearson correlation analysis revealed significant associations between various gut microbes and immune-related metabolites, suggesting that Cd may alter the immune system of P. pseudoannulata by modulating its gut microbiota.

Histopathological Changes and Metallothionein Levels in Filopaludina javanica During Depuration

The heavy metal lead has been reported to pollute waters along the Glagah River, Lamongan Regency, Indonesia. Lead contamination in all organs of the Tutut snail (Filopaludina javanica) was detected at 2.92 ± 0.5 ppm. Therefore, lead contamination can cause severe problems because lead can accidentally accumulate in the human body through the food chain. One effort to reduce risks related to food safety is Depuration. The research aimed to analyze the effect of Depuration using a flushing system on histopathological changes and metallothionein levels in all organs of the spotted snail (Filopaludina javanica). The research used a Completely Randomized Design with four treatments and three replications. Treatment includes flushing time (6 hours, 12 hours, 18 and 24 hours). The MT response was tested statistically using One Way Anova, while the histopathological analysis used a descriptive method by comparing before treatment and after flushing treatment for 24 hours, to determine metallothionein levels, the ELISA (Enzyme-Linked Immunosorbent Assay) method was used. The results showed tissue damage in edema, hyperplasia, and vacuolation. Tissue damage before and after Depuration was relatively the same and included in the low category, with damage ranging from (0-6.1%). Meanwhile, metallothionein analysis has not shown a significant decrease in levels. Metallothionein levels increased with the duration of flushing. Further checks showed that the media water used in flushing during Depuration contained Fe and Zn, which resulted in increased MT levels

An ecofriendly approach to bioremediate nickel oxide nanoparticles using a macrofungus, Pleurotus fossulatus.

Nowadays, nickel oxide nanoparticles are in great demands owing to their use in many sectors. These nanoparticles may release into aquatic environment from different industries and cause negative effect on aquatic flora and fauna. Therefore, an effective and efficient method is required to remove these nanoparticles from contaminated water. Hence, the aim of this study was to bioremediate nickel oxide nanoparticles using a macrofungus, Pleurotus fossulatus, and to analyze its impact on fungal physiology. For this purpose, fungal spawns were inoculated in malt dextrose agar media containing different concentrations of nickel oxide nanoparticles (24mg/l, 48mg/l, and 100mg/l) as well as control group (having no nickel oxide nanoparticles) and allowed to grow for a period of 20days. Fungal mycelia as well as media were collected at different time intervals (5th day, 10th day, 15th day, and 20th day) for evaluation of Ni concentration and different biochemical parameters. Ni removal efficiency of P. fossulatus from media was found to be highest in 48mg/l (66.98%) followed by 24mg/l (60.83%) and 100mg/l (18.03%), respectively. Increased level of metallothionein, lipid peroxidation, activity of different antioxidant enzymes (superoxide dismutase, catalase, glutathione s transferase, glutathione reductase), activity of ligninolytic enzymes (laccase, lignin peroxidase, manganese peroxidase), and shift in FTIR spectra were also reported in mycelia cultured in malt dextrose agar media containing nickel oxide nanoparticles. This study suggests that P. fossulatus has great efficiency to remediate nanoparticles from contaminated water and it can be utilized as potential agent in wastewater treatment plants by different industries.

Zinc modulates hypothalamo-pituitary-gonadal-liver axis to impair reproduction in female Mystus vittatus (Bloch, 1794).

The present study investigated the effects of zinc on the hypothalamo-pituitary-gonadal-liver (HPGL) axis of the bagrid catfish Mystus vittatus. Female fish (pre-ovulatory and ovulatory phases) were exposed to zinc sulphate at 1/10th of LC50 (5.62mg/L) for 60days and sacrificed at every 15-day interval to collect tissues. Zinc concentration in all tissues was significantly higher in the metal-exposed group at all exposure durations compared to control for both phases. Metallothionein (MT) levels increased in the brain, liver and ovary of fish from both phases with exposure duration. Reactive oxygen species (ROS) generation in the brain, liver and ovary tissues increased with exposure duration at both reproductive phases while serum cortisol levels in ovulatory fish increased significantly compared to pre-ovulatory. Condition factor, gonadosomatic index and hepatosomatic index decreased in Zn-exposed fish. Brain GnRH and kisspeptin levels decreased significantly in the Zn-exposed group for both phases. GnIH was significantly higher in Zn-exposed fish. Serum FSH levels in pre-ovulatory and LH levels in ovulatory fish decreased gradually with an increase in the duration of exposure. Zn exposure reduced vitellogenin (Vtg) and estradiol (E2) in the liver and ovary with an increase in duration from both phases. Ovary maturation-inducing hormone (MIH) levels showed a decrease with exposure duration in ovulatory fish. Moreover, Zn-exposed ovulatory fish showed a degenerated oocyte nucleus due to the disintegration of the nuclear membrane. It might be inferred that Zn altered the HPGL regulatory system of M. vittatus reproduction at both the pre-ovulatory and ovulatory phases.

Effect of initial periodontal therapy on metallothionein levels in smokers and non-smokers with periodontitis.

The aim of this study was to determine the effect of non-surgical periodontal therapy (NSPT) on mRNA expression of metallothionein (MT) and its levels in serum, saliva and gingival crevicular fluid (GCF) of smokers (S) and non-smokers (NS) with periodontitis (P).A total of 100 participants were included: 48 periodontally healthy (PH) subjects (24 S [PH + S] and 24 NS [PH + NS]) and 52 patients with P (27 S [P + S] and 25 NS [P + NS]). Clinical parameters were recorded, and biofluids (serum, saliva and GCF) and gingival tissue samples were obtained at baseline in all groups and 3months after NSPT in P groups. MT levels in biofluids were determined by ELISA. In gingival tissues, MT-mRNA expression was quantified using real-time PCR. mRNA expression of MT and its levels in biofluids were significantly higher in P + S compared to other groups, and the differences between P + NS and PH + S were non-significant. A significant decrease was observed for MT levels in biofluids, and MT-mRNA expression in periodontitis patients after NSPT. In conclusion, smoking and periodontitis are associated with higher MT expression which decreases after NSPT. MT as an oxidative stress biomarker and its therapeutic role in periodontitis should be investigated in future studies.Clinical trial registration: The study was prospectively registered at Clinical Trials Registry-India (ctri.nic.in) as CTRI/2018/08/015427 on August 23, 2018.

Abstract LB299: Dihydrouridine synthase 2 sustains levels of tRNACys and prevents ferroptosis in lung cancer

Abstract Dihydrouridine is a universally conserved tRNA modification installed by enzymes that are important for human health. High expression of dihydrouridine synthase 2 (DUS2) predicts poor patient outcomes in lung adenocarcinoma (LUAD) for reasons that are not yet clear. Here, we show in human cells and mouse xenografts that DUS2 suppresses ferroptosis, a metal-dependent non-apoptotic form of cell death that is emerging as a therapeutic target in lung cancer. Elevated DUS2 correlates with resistance to ferroptosis inducers and loss of DUS2 causes increased sensitivity with concomitant accumulation of toxic lipid peroxides. Mechanistically, DUS2 is required to maintain tRNA CysGCA levels, supporting translation of cysteine-rich proteins including metallothioneins, key regulators of metal and redox homeostasis Notably, DUS2 KO cells cannot sustain normal levels of metallothioneins, a class of very cysteine rich proteins that serve as key regulators of both metal and redox homeostasis. Accordingly, DUS2 knockout cells are more susceptible to zinc intoxication and have lower levels of reduced glutathione, which partially explains their sensitivity to ferroptosis. Our findings demonstrate that DUS2 is required to support tRNACys levels and fend off ferroptosis in lung cancer cells. This highlights that individual tRNA substrates can play an outsized role in the biological functions of tRNA modifying enzymes, and demonstrates the therapeutic potential of targeting DUS2 in cancer. Citation Format: Austin Draycott, Matthew C. Wang, Diana Martínez Saucedo, Luisa Escobar-Hoyos, Wendy Gilbert. Dihydrouridine synthase 2 sustains levels of tRNACys and prevents ferroptosis in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB299.

Blockage of metallothionein synthesis via adrenaline β receptor activation invalidates dehydroeffusol-mediated prevention of amyloid β1-42 toxicity

Dehydroeffusol, a major phenanthrene in Juncus effusus, protects neurodegeneration induced by intracellular Zn2+ ferried by extracellular amyloid β1-42 (Aβ1-42). Here we focused on adrenaline β receptor activation and the induction of metallothioneins (MTs), intracellular Zn2+-binding proteins to test the protective mechanism of dehydroeffusol. Isoproterenol, an agonist of adrenergic β receptors elevated the level of MTs in the dentate granule cell layer 1 day after intracerebroventricular (ICV) injection. When Aβ1-42 was injected 1 day after isoproterenol injection, pre-injection of isoproterenol protected Aβ1-42 toxicity via reducing the increase in intracellular Zn2+ after ICV injection of Aβ1-42. On the basis of the effect of increased MTs by isoproterenol, dehydroeffusol (15 mg/kg body weight) was orally administered to mice once a day for 2 days. On day later, dehydroeffusol elevated the level of MTs and prevented Aβ1-42 toxicity via reducing Aβ1-42-mediated increase in intracellular Zn2+. In contrast, propranolol, an antagonist of adrenergic β receptors reduced the level of MTs increased by dehydroeffusol, resulting in invalidating the preventive effect of dehydroeffusol on Aβ1-42 toxicity. The present study indicates that blockage of MT synthesis via adrenaline β receptor activation invalidates dehydroeffusol-mediated prevention of Aβ1-42 toxicity. It is likely that MT synthesis via adrenaline β receptor activation is beneficial to neuroprotection and that oral intake of dehydroeffusol preventively serves against the Aβ1-42 toxicity.

Toxic effect of chromium on nonspecific immune, bioaccumulation, and tissue structure of Urechis unicinctus.

The contamination of toxic heavy metals in aquatic environments has garnered significant global attention due to its detrimental effects on marine organisms and human health. Hexavalent chromium is a typical environmental and occupational heavy metal pollutant, identified as carcinogenic heavy metal. This study aimed to assess the impact of different Cr (VI) concentrations (0.05-2.5 mg/L) on Urechis unicinctus (U. unicinctus) by investigating bioaccumulation, antioxidant defense system, expression of resistance-related genes, and histological issues. A clear concentration-effect relationship was observed in the bioaccumulation of Cr (VI) in muscle tissues of U. unicinctus. Moreover, exposure to Cr (VI) can alter the activities of lysozyme (LSZ), catalase (CAT), and superoxide dismutase (SOD) to enhance cellular defense mechanisms in U. unicinctus. Likewise, maintained the normal protein structure and functional stability by regulating protein folding. The heat shock cognitive protein (HSC70) gene showed an upward and then downward trend after Cr (VI) exposure. At 12 h, the HSC70 gene expression reached the maximum values of 4.75 and 4.61-fold in the 0.1 and 1.5 mg/L groups, respectively. The organism produced a large number of free radicals, and elevated level of metallothionein (MT) was used to scavenge free radicals and alleviate oxidative stress. Additionally, histopathological examination revealed disorganization in the midgut, atrophic changes in intestinal connective tissue, uneven distribution in respiratory tissues, and irregular shape with a significant reduction in epithelial cells within the gastric cavity. These findings can serve as a valuable reference for elucidating the toxicity mechanisms of heavy metals towards marine benthic organisms and enhancing water environment monitoring strategies.

Zinc mitigates cadmium-induced sperm dysfunction through regulating Ca2+ and metallothionein expression in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a highly toxic heavy metal element that might adversely affect sperm function such as the acrosome reaction (AR). Although it is widely recognized that zinc (Zn) plays a crucial role in sperm quality, the complete elucidation of how Zn ameliorates Cd-induced sperm dysfunction is still unclear. In this study, we aimed to explore the protective effects of Zn against the sperm dysfunction induced by Cd in the freshwater crab Sinopotamon henanense. The results demonstrated that Cd exposure not only impaired the sperm ultrastructure, but also caused sperm dysfunction by decreasing the AR induction rate, acrosome enzyme activity, and Ca2+ content in sperm while elevating the activity and transcription expression of key Ca2+ signaling pathway-related proteins Calmodulin (CAM) and Ca2+-ATPase. However, the administration of Zn was found to alleviate Cd-induced sperm morphological and functional disorders by increasing the activity and transcription levels of CaM and Ca2+-ATPase, thereby regulating intracellular Ca2+ homeostasis and reversing the decrease in Ca2+ contents caused by Cd. Furthermore, this study was the first to investigate the distribution of metallothionein (MT) in the AR of S. henanense, and it was found that Zn can reduce the elevated levels of MT in crabs caused by Cd, demonstrating the significance of Zn in inducing MT to participate in the AR process and in metal detoxification in S. henanense. These findings offer novel perspectives and substantiation regarding the utilization of Zn as a protective agent against Cd-induced toxicity and hold significant practical implications for mitigating Cd-induced sperm dysfunction.

Effect of salinity on the toxicokinetics, oxidative stress, and metallothionein gene expression in Meretrix meretrix exposed to cadmium

To understand the effect of salinity on the toxicokinetics, oxidative stress, and detoxification of cadmium-exposed Meretrix meretrix, M. meretrix were acclimatized to different salinities (8, 14, 20, 26, and 32 ppt) for 14 d, exposed to 10 μg/L Cd for 7 d, followed by a 28-day depuration period. The internal Cd concentration was determined, and the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST)), and the malondialdehyde (MDA) content were measured. The mRNA expression levels of antioxidant enzyme (Cu/Zn SOD, CAT) and detoxification-related genes metallothionein (MT) were analyzed. The mean concentrations of Cd in M. meretrix tissues were in the order gill > digestive gland > mantle > axe foot. The Cd uptake rate in the four tissues decreased with increasing salinity (range: 14–26 ppt). The Cd elimination half-lives were the highest at 8 ppt and 14 ppt salinity. Cadmium activated the four oxidative stress-related related enzymes in the gills. At the end of accumulation period, Cd exposure at 20 ppt salinity significantly increased the expression of Cu/Zn SOD. CAT expression was significantly inhibited at 20 ppt salinity, but was induced at 32 ppt. MT mRNA expression was only induced under Cd at 20 ppt salinity. At the end of depuration period, Cu/Zn SOD expression was inhibited at salinities of 8, 14, and 26 ppt. The results indicated that SOD, CAT, GST, MDA, Cu/Zn SOD, CAT, and MT were sensitive to cadmium in a water environment, and can be used as indicators of marine heavy metal pollution.

Antioxidant system alterations, oxidative, and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a dumpsite.

Water body contamination by leachate originated from dumpsites is a concern for municipal solid waste (MSW) management. In this context, this study aimed to evaluate antioxidant system alterations and oxidative and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a closed dumpsite. Groups comprising 50 fish were exposed (96 h) to different leachate concentrations (5, 15, 30, and 50%) to evaluate effects on liver and brain superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities and reduced glutathione (GSH) and metallothionein (MT) concentrations, as well as malondialdehyde (MDA) and protein carbonylation (PTC) levels. Blood genotoxicity was evaluated by the comet assay. The investigated dumpsite leachate pond presented high chloride concentrations (Cl-; 2288.4 ± 69.5 mg L-1) and high electrical conductivity (EC; 8434.0 mS cm-1), indicating the presence of leachate. Concerning Danio rerio exposure, higher SOD (37%), CAT (67%), and GST (39%) activities and higher GSH (57%) concentrations were observed in liver following exposure to 50% leachate, while decreased brain GST (42%) activities and GSH (90%) levels were observed at the same leachate concentration. A significant increase in the olive tail moment (OTM; 280%) indicative of genotoxicity in blood was observed. A principal component analysis indicated that increased enzymatic activities and high levels of both GSH and MT were not sufficient to prevent the accumulation of reactive oxygen species, resulting in PTC and genotoxicity. Therefore, leachate exposure causes sublethal Danio rerio effects, altering the antioxidant system, increasing ROS production, and leading to PTC and genotoxicity. The findings demonstrate the need to further develop sublethal level assessments in zebrafish using leachate from different sources to subsidize risk assessments regarding MSW management.

Biomarker response index in earthworms following chronic exposure to leachate from a closed dumpsite: Behavioral, cytotoxicity and antioxidant system alterations

Leachate, an effluent produced during solid waste decomposition, interacts directly with soil, mainly in dumpsite areas. Studies on terrestrial animal exposure to leachate are, however, lacking. Plants are the most frequently studied organisms, while animal studies, especially earthworms, are limited. Nevertheless, ecotoxicological assessments involving earthworms are crucial due to their role in soil health and ecosystem maintenance, which are paramount in understanding potential terrestrial ecosystem leachate effects. In this context, this study aimed to evaluate behavioral effects, sublethal cytotoxicity and antioxidant system alterations in Eisenia andrei earthworms chronically exposed to leachate from a closed dumpsite. Cytotoxicity was determined by coelomocyte density, viability and cell typing, while antioxidant system alterations were assessed through superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), reduced glutathione (GSH) and metallothionein (MT) determinations. Malondialdehyde (MDA) and protein carbonylation (PTC) levels were also determined as oxidative effect markers. Finally, the Biomarker Response Index (BRI) was assessed, aiming to quantitatively integrate the results of the investigated endpoints and establish a biological health state (BHS) for each leachate concentration. Leachate exposure led to leak responses at concentrations of up to 50%, but attraction at higher concentrations. Decreased cell density (28%) was observed after 48 days and reduced viability (50%), after 14 days of leachate exposure. The observed cell typing changes indicate anti-inflammatory immune system effects. Leachate exposure led to several antioxidant system alterations, increasing SOD (2–6 %), CAT (5–35 %) and GST (5–70 %) activities and GSH (7–37%) and MT (3–67%) levels. Earthworm antioxidant defenses were, however, able to prevent lipid peroxidation, which decreased (11–37%) following leachate exposure to concentrations above 12.5%, and PTC, which increased at 42 days (26%) and reduced at 56 days (12 %). This is the first PTC assessment in leachate-exposed earthworms. The increased carbonylation levels observed after 42 days alongside MDA decreases highlight the need for further research employing oxidative effect biomarkers other than MDA. Finally, an integrated approach employing the BRI was carried out, revealing mild initial changes evolving to moderate to major effects at the highest leachate exposure concentration, with an effect attenuation detected at the end of the experiment. In this sense, this study brings forth a significant novelty, employing a biomarker previously not assessed in earthworms, demonstrating an oxidative effect, alongside the use of the BRI as an integrative tool for the endpoints applied in this assessment.

Long-term exposure to lead nitrate and zinc sulfate Nile tilapia impact the Aeromonas hydrophila treatment

BackgroundPollution with heavy metals (HMs) is time- and concentration-dependent. Lead and zinc pollute the aquatic environment, causing severe health issues in aquatic animals.Materials and methodsNile tilapia, the predominant cultured fish in Egypt, were experimentally exposed to 10% of LC50 of lead nitrate (PbNO3) and zinc sulfate (ZnSO4). Samples were collected in three different periods, 4, 6, and 8 weeks, in addition to a trial to treat the experimental fish infected with Aeromonas hydrophila, with an antibiotic (florfenicol).ResultsLiver enzymes were linearly upsurged in a time-dependent manner in response to HMs exposure. ALT was 92.1 IU/l and AST was 82.53 IU/l after eight weeks. In the eighth week of the HMs exposure, in the hepatic tissue, the levels of glutathione peroxidase (GPx), catalase (CAT), and metallothionein (MT) were increased to 117.8 U/mg prot, 72.2 U/mg prot, and 154.5 U/mg prot, respectively. On exposure to HMs, gene expressions of some cytokines were linearly downregulated in a time-dependent manner compared to the control. After four weeks of exposure to the HMs, the oxidative burst activity (OBA) of immune cells was decreased compared to the control 9.33 and 10.3 cells, respectively. Meanwhile, the serum bactericidal activity (SBA) significantly declined to 18.5% compared to the control 32.6% after eight weeks of exposure. Clinical signs of A. hydrophila infection were exaggerated in polluted fish, with a mortality rate (MR) of 100%. The re-isolation rate of A. hydrophila was decreased in fish treated with florfenicol regardless of the pollution impacts after eight weeks of HMs exposure.ConclusionIt could be concluded that the immune suppression and oxidative stress resulting from exposure to HMs are time-dependent. Clinical signs and post-mortem lesions in polluted fish infected with A. hydrophila were prominent. Infected-Nile tilapia had weak responses to florfenicol treatment due to HMs exposure.

Metallothionein 3 Potentiates Pulmonary Artery Smooth Muscle Cell Proliferation by Promoting Zinc-MTF1-ATG5 Axis-mediated Autophagosome Formation.

Abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs) is one of the critical pathological mechanisms of pulmonary hypertension (PH), and therefore is gradually being adopted as an important direction for the treatment of PH. Metallothioneins (MTs) have been reported to be associated with PH, but the underlying mechanisms are not fully understood. Here, we demonstrated that the expression level of metallothionein 3 (MT3) was significantly increased in pulmonary arterioles from PH patients and chronic hypoxia-induced rat and mouse PH models, as well as in hypoxia-treated human PASMCs. Knockdown of MT3 significantly inhibited the proliferation of human PASMCs by arresting the cell cycle in the G1 phase, while overexpression of MT3 had the opposite effect. Mechanistically, we found that MT3 increased the intracellular zinc (Zn2+) concentration to enhance the transcriptional activity of metal-regulated transcription factor 1 (MTF1), which promoted the expression of autophagy-related gene 5 (ATG5), facilitating autophagosome formation. More importantly, MT3-induced autophagy and proliferation of human PASMCs were largely prevented by knockdown of MTF1 and ATG5. Therefore, in this study, we identified MT3-Zinc-MTF1-ATG5 as a novel pathway that affects PASMC proliferation by regulating autophagosome formation, suggesting that MT3 may be a novel target for the treatment of PH.

Adverse outcome pathways as a tool for optimization of the biomarker-based assessment of pollutant toxicity: A case study of cadmium in the blue mussels Mytilus edulis

Technogenic metals like cadmium (Cd) are discharged into the environment posing significant ecological risks to wildlife and contributing to a decline in biodiversity. Recent developments in toxicity testing and environmental risk assessment have shifted the focus towards prioritizing biological effects. To ensure effective environmental risk assessment, it is essential to develop sensitive sub-organismal biomarkers correlated with ecologically relevant organismal-level responses. Our study proposes a novel approach to enhance the evaluation of biomarker-based toxicity based on adverse outcome pathways (AOP) concept. We exposed the blue mussels M. edulis to Cd concentrations ranging from 200 to 600 µg l−1 (10–30 % of LC50) for 14 days, and assessed a comprehensive panel of 26 biomarkers related to molecular initiation events (Cd uptake and binding), key cellular events (oxidative stress, metabolic disturbances, and cytotoxicity), and adverse organismal outcomes (survival, energy metabolism, and reef-building capacity) in the putative AOP of Cd. Tissue Cd burdens increased linearly with exposure concentrations in the mussels. Although the condition index of the mussels remained unaffected, their biofiltration activity was suppressed at the highest Cd concentration. The negative effects of Cd exposure on the mussels' feeding were linked to reduced energetic scope for growth, impaired byssus production, increased hemocyte mortality, and altered functional traits of hemocytes. Additionally, Cd exposure induced oxidative stress, as evidenced by lower total antioxidant capacity and thiol pool, along with increased lipid peroxidation, leading to enhanced autophagy. Through Random Forest Analysis, we identified a minimal set of sensitive Cd effect biomarkers, including hemocyte mortality (contributing ∼0.32 to classification accuracy), hemocyte acid phosphatase activity, nitric oxide and metallothionein levels in the digestive gland, and whole-organism clearance rate and scope for growth (each contributing ∼0.02–0.08 to classification accuracy). These biomarkers collectively achieved a high accuracy of 90–100 % in distinguishing between control and Cd-exposed groups. Increasing the number of biomarkers did not improve classification accuracy. These findings suggest that using a smaller number of optimized biomarkers based on Adverse Outcome Pathways (AOP) can enhance the assessment of contaminant-induced negative effects while reducing testing costs in environmental risk assessments.

Biochemical response and tissue-specific accumulation of scallop Aequipecten tehuelchus from Patagonia, Argentina after exposure to inorganic arsenic

This study investigates the effects of different inorganic arsenic (As III) concentrations (0, 125, 500 and 1000 μg As/L) following two exposure times (7 and 14 days) on gills, digestive gland and muscle of scallop Aequipecten tehuelchus from Patagonia, Argentina. A biochemical approach was used to investigate oxidative stress-related parameters after different As concentrations and exposure times. Although the accumulation of As was of the same order of magnitude in all tissues, the results showed distinct tissue-specific oxidative responses to this metalloid. Furthermore, the variation in exposure time had no significant effect on As accumulation in any of the three tissues. In gills, despite no reactive oxygen and nitrogen species (RONS) were detected, there was an increase in catalase (CAT) activity and metallothionein (MT) levels. Conversely, digestive gland showed RONS production without a rise in CAT and glutathione S-transferases (GST) activities, but with an increase in MT levels. In muscle, RONS production and CAT activity kept constant or decreased, while MT levels remained unchanged. In addition, exposure time demonstrated its critical role in gills by influencing the response of CAT, GST and MT, particularly at high As concentrations, while exposure time did not affect the biochemical stress parameters in the digestive gland and muscle. Interestingly, neither concentration of As produced lipid damage, showing the effectiveness of the antioxidant mechanisms to avoid it. These results emphasize that A. tehuelchus exhibited no time-dependent effects in response to As exposure, while showing tissue-specific responses characterized by significant concentration-dependent effects of As. This study provides a comprehensive insight by considering the combined effects of time and concentration of a contaminant and distinguishing its effects on specific tissues, a dimension often overlooked in the existing literature. Subsequent studies should prioritize the analysis of additional contaminants in species with increased sensitivity.

Saccharomyces cerevisiae additions normalized hemocyte differential genes expression and regulated crayfish (Procambarus clarkii) oxidative damage under cadmium stress

Because China produces the most crayfish in the world, safe solutions must be improved to mitigate the risks of ongoing heavy metal stressors accumulation. This study aimed to use Saccharomyces cerevisiae as a bioremediation agent to counteract the harmful effect of cadmium (Cd) on crayfish (Procambarus clarkia). Our study used three concentrations of S. cerevisiae on crayfish feed to assess their Cd toxicity remediation effect by measuring total antioxidant capacity (TAC) and the biomarkers related to oxidative stress like malondialdehyde (MDA), protein carbonyl derivates (PCO), and DNA–protein crosslink (DPC). A graphite furnace atomic absorption spectroscopy device was used to determine Cd contents in crayfish. Furthermore, the mRNA expression levels of lysozyme (LSZ), metallothionein (MT), and prophenoloxidase (proPO) were evaluated before and following the addition of S. cerevisiae. The results indicated that S. cerevisae at 5% supplemented in fundamental feed exhibited the best removal effect, and Cd removal rates at days 4th, 8th, 12th, and 21st were 12, 19, 29.7, and 66.45%, respectively, which were significantly higher than the basal diet of crayfish. The addition of S. cerevisiae increased TAC levels. On the other hand, it decreased MDA, PCO, and DPC, which had risen due to Cd exposure. Furthermore, it increased the expression of proPO, which was reduced by Cd exposure, and decreased the expression of LSZ and MT, acting in the opposite direction of Cd exposure alone. These findings demonstrated that feeding S. cerevisiae effectively reduces the Cd from crayfish and could be used to develop Cd-free crayfish-based foods.