Metallothionein Production Research Articles

Construction and biological activity of metallothionein fused with ELP

Metallothionein (MT) plays a significant role in heavy metal removal, antioxidant defense, and immune regulation. The current predominant approach for obtaining natural MT is extraction from tissue, which often entails complex procedures resulting in limited yields. In recent years, researchers have adopted the strategy of fusing labels such as GST or His for the heterologous expression of MT. However, a challenge in industrial production arises from the subsequent removal of these labels, which often leads to a significant reduction in the yield. The fusion with elastin-like polypeptides (ELPs) offers a promising solution for achieving soluble expression of the target protein, while providing a simple and fast purification process. In this study, ELP was fused with MT, which significantly up-regulated the soluble expression of MT. The fusion protein ELP-MT with the purity above 97% was obtained efficiently and simply by inverse transition cycling (ITC). ELP-MT exhibited a remarkable 2,2'-azinobis(3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) scavenging activity, with the half maximal inhibitory concentration (IC50) of 0.77 μmol/L, which was 53.7 times that of the vitamin E derivative Trolox. In addition, the fusion protein demonstrated strong 1,1-diphenyl-2-trinitrohydrazine (DPPH) scavenging ability. Furthermore, ELP-MT had no toxicity to the proliferation and promoted the adhesion and migration of NIH/3T3 cells. All these results indicated that ELP-MT had good biocompatibility. We constructed the fusion protein ELP-MT combining the unique properties of MT and elastin, laying a technical foundation for the large-scale production of recombinant MT and facilitating the applications in food, health supplement, and cosmetic industries.

Development of Reactivity for Organobismuth (III, V) Toward Sulfur-Containing Compounds

Organobismuth compounds have been used in various areas of science, like biology and organic synthesis, because they are normally nontoxic and exhibit unique properties. Bismuth induces metallothionein production and is known to exhibit thiophilicity. However, few reports on the reactions between bismuth and sulfur compounds exist. This article reviews studies on the reactivity of bismuth (III and V) with sulfur compounds. A simple approach for the reaction of azole-2-thiones, which contains a heterocyclic ring, with triaryl bismuthines in the presence of a copper catalyst affords the S-arylated coupling product. When a palladium catalyst is used instead of a copper catalyst, desulfinative C-C bond formation occurs. These reactions indicate that trivalent bismuth compounds can be used as novel aryl sources. Triphenylbismuth dichloride, an organobismuth (V) reagent, successfully promotes the cyclodesulfurization of thioureas within short reaction times under mild conditions. The reaction affords N-substituted benzoxazol-2-amines in excellent yields. Tafamidis, a drug used to treat transthyretin amyloidosis, can be synthesized using this reaction.

A Potential Involvement of Metallothionein in the Zinc Tolerance of Trichoderma harzianum: Experimental Findings.

Metallothioneins are a group of cysteine-rich proteins that play an important role in the homeostasis and detoxification of heavy metals. The objective of this research was to explore the significance of metallothionein in Trichoderma harzianum tolerance to zinc. At the inhibitory concentration of 1000 ppm, the fungus adsorbed 16.7 ± 0.4mg/g of metal. The HPLC and SDS-PAGE electrophoresis data suggested that the fungus production of metallothionein was twice as high in the presence of zinc as in the control group. The examination of the genes; metallothionein expression activator (MEA) and Cu fist revealed that the MEA, with a C2H2 zinc finger domain, increased significantly in the presence of zinc. It was observed that in T. harzianum, the enhanced expression of the metallothionein gene was managed by the metallothionein activator under zinc overload conditions. According to our knowledge, this is the first report on the role of metallothionein in the resistance of T. harzianum to zinc.

Histopathological effects of long-term exposure to realistic concentrations of cadmium in the hepatopancreas of Sparus aurata juveniles

In recent decades, cadmium has emerged as an environmental stressor in aquatic ecosystems due to its persistence and toxicity. It can enter water bodies from various natural and anthropogenic sources and, once introduced into aquatic systems, can accumulate in sediments and biota, leading to bioaccumulation and biomagnification in the food chain. For this reason, the effects of cadmium on aquatic life remain an area of ongoing research and concern. In this paper, a multidisciplinary approach was used to assess the effects of long-term exposure to an environmental concentration on the hepatopancreas of farmed juveniles of sea bream, Sparus aurata. After determining metal uptake, metallothionein production was assessed to gain insight into the organism's defence response. The effects were also assessed by histological and ultrastructural analyses. The results indicate that cadmium accumulates in the hepatopancreas at significant concentrations, inducing structural and functional damage. Despite the parallel increase in metallothioneins, fibrosis, alterations in carbohydrate distribution and endocrine disruption were also observed. These effects would decrease animal fitness although it did not translate into high mortality or reduced growth. This could depend on the fact that the animals were farmed, protected from the pressure deriving from having to search for food or escape from predators. Not to be underestimated is the return to humans, as this species is edible. Understanding the behaviour of cadmium in aquatic systems, its effects at different trophic levels and the potential risks to human health from the consumption of contaminated seafood would therefore be essential for informed environmental management and policy decisions.

The Anti-Oxidative, Anti-Inflammatory, Anti-Apoptotic, and Anti-Necroptotic Role of Zinc in COVID-19 and Sepsis.

Zinc is a structural component of proteins, functions as a catalytic co-factor in DNA synthesis and transcription of hundreds of enzymes, and has a regulatory role in protein-DNA interactions of zinc-finger proteins. For many years, zinc has been acknowledged for its anti-oxidative and anti-inflammatory functions. Furthermore, zinc is a potent inhibitor of caspases-3, -7, and -8, modulating the caspase-controlled apoptosis and necroptosis. In recent years, the immunomodulatory role of zinc in sepsis and COVID-19 has been investigated. Both sepsis and COVID-19 are related to various regulated cell death (RCD) pathways, including apoptosis and necroptosis. Lack of zinc may have a negative effect on many immune functions, such as oxidative burst, cytokine production, chemotaxis, degranulation, phagocytosis, and RCD. While plasma zinc concentrations decline swiftly during both sepsis and COVID-19, this reduction is primarily attributed to a redistribution process associated with the inflammatory response. In this response, hepatic metallothionein production increases in reaction to cytokine release, which is linked to inflammation, and this protein effectively captures and stores zinc in the liver. Multiple regulatory mechanisms come into play, influencing the uptake of zinc, the binding of zinc to blood albumin and red blood cells, as well as the buffering and modulation of cytosolic zinc levels. Decreased zinc levels are associated with increasing severity of organ dysfunction, prolonged hospital stay and increased mortality in septic and COVID-19 patients. Results of recent studies focusing on these topics are summarized and discussed in this narrative review. Existing evidence currently does not support pharmacological zinc supplementation in patients with sepsis or COVID-19. Complementation and repletion should follow current guidelines for micronutrients in critically ill patients. Further research investigating the pharmacological mechanism of zinc in programmed cell death caused by invasive infections and its therapeutic potential in sepsis and COVID-19 could be worthwhile.

Production of Intestinal Mucins, sIgA, and Metallothionein after Administration of Zinc and Infection of Ascaridia galli in Chickens: Preliminary Data.

The effect of inorganic zinc and Ascaridia galli infection was studied on MUC1, MUC2 (mucin), sIgA (secretory immunoglobulin A), and metallothionein in the intestines of broilers. Thirty-five-day-old chickens (n = 24), COBB 500 breed, were included in a 14-day experiment. Chickens were divided into 4 groups of 6 chickens each: control ©, Ascaridia galli (AG), Zinc group (Zn), and combined group (AG + Zn). Samples from the intestine for determination of MUC1, MUC2, sIgA, and metallothionein were taken at 7 and 14 days during necropsy. Samples from the jejunum for determination of MUC1, MUC2, sIgA, and metallothionein were taken at 7 and 14 days during necropsy. The results demonstrated that 12 days' administration of inorganic zinc increased production of MUC1 (p < 0.0001) and MUC2 (p < 0.001) in the Ascaridia galli-infected group (Ag + Zn) in comparison to control (C). The beneficial effect of zinc was also revealed in the production of sIgA (p < 0.0001) in the combined group (AG + Zn) at 7 days. The concentration of metallothionein increased mainly in the zinc group (p < 0.01) of first sampling and was upregulated in Zn and AG + Zn groups. The obtained data indicate the use of inorganic zinc as a suitable immunomodulator of intestinal immunity in Ascaridia galli-infected chickens.

Physio-Biochemical and Transcriptomic Features of Arbuscular Mycorrhizal Fungi Relieving Cadmium Stress in Wheat.

Arbuscular mycorrhizal fungi (AMF) can improve plant cadmium (Cd) tolerance, but the tolerance mechanism in wheat is not fully understood. This study aimed to examine the physiological properties and transcriptome changes in wheat inoculated with or without Glomus mosseae (GM) under Cd stress (0, 5, and 10 mg·kg-1 CdCl2) to understand its role in wheat Cd tolerance. The results showed that the Cd content in shoots decreased while the Cd accumulation in roots increased under AMF symbiosis compared to the non-inoculation group and that AMF significantly promoted the growth of wheat seedlings and reduced Cd-induced oxidative damage. This alleviative effect of AMF on wheat under Cd stress was mainly attributed to the fact that AMF accelerated the ascorbate-glutathione (AsA-GSH) cycle, promoted the production of GSH and metallothionein (MTs), improved the degradation of methylglyoxal (MG), and induced GRSP (glomalin-related soil protein) secretion. Furthermore, a comparative analysis of the transcriptomes of the symbiotic group and the non-symbiotic group revealed multiple differentially expressed genes (DEGs) in the 'metal ion transport', 'glutathione metabolism', 'cysteine and methionine metabolism', and 'plant hormone signal transduction' terms. The expression changes of these DEGs were basically consistent with the changes in physio-biochemical characteristics. Overall, AMF alleviated Cd stress in wheat mainly by promoting immobilization and sequestration of Cd, reducing ROS production and accelerating their scavenging, in which the rapid metabolism of GSH may play an important role.

The protease DDI2 regulates NRF1 activation in response to cadmium toxicity

SummaryDNA-damage inducible 1 homolog 2 (DDI2) is a protease that activates the transcription factor NRF1. Cellular models have shown that this pathway contributes to cell-stress adaptation, for example, on proteasome inhibition. However, DDI2 physiological function is unknown. Ddi2 Knock-out (KO) mice were embryonic lethal. Therefore, we generated liver-specific Ddi2-KO animals and used comprehensive genetic analysis to identify the molecular pathways regulated by DDI2. Here, we demonstrate that DDI2 contributes to metallothionein (MT) expression in mouse and human hepatocytes at basal and upon cadmium (Cd) exposure. This transcriptional program is dependent on DDI2-mediated NRF1 proteolytic maturation. In contrast, NRF1 homolog NRF2 does not contribute to MT production. Mechanistically, we observed that Cd exposure inhibits proteasome activity, resulting in DDI2-mediated NRF1 proteolytic maturation. In line with these findings, DDI2 deficiency sensitizes cells to Cd toxicity. This study identifies a function for DDI2 that links proteasome homeostasis to heavy metal mediated toxicity.

EFFECT OF CADMIUM AND ZINC HEAVY METALS ON THE SOIL BACTERIA ISOLATED FROM COAL MINE REGION

Study of growth pattern of isolated soil bacteria from Raniganj coal mine area shows an unusual increase in growth rate of the isolated bacteria when treated with heavy metal stress in the culture media. The metals used were Cadmium (Cd) and Zinc (Zn). Utilization of metal ions by the bacterial cells was studied by detection of leftover metal in the culture medium after optimal growth, by Dithizone method and surface adsorption of metal ions on bacterial cell by FTIR technique. The amount of total thiol and non-protein thiol of the bacterial culture was assayed for the presence of thiol containing protein like Metallothionein. Metallothionein production was also studied using SDS-PAGE and Western blot technique to find if the cells were stressed in the presence of increasing concentration of Zn2+ and Cd2+. Metallothioneins (MTs) are proteins rich in cysteine residues having low molecular weight. They perform different functions like scavenging of free radicals, involvement in maintaining metal balance, regulation of metabolic activities and protective role against damage caused by heavy metals. Metallothioneins can be correlated with heavy metal contamination of an environment and thus may be considered as bio-marker for environmental pollution.

Metallothionein expression in Aspergillus exposed to environmentally relevant concentrations of heavy metals at different pH levels.

Heavy metal pollution represents a health threat. Many fungal species are capable of tolerating various heavy metals, especially if they are isolated from a contaminated watercourse. One of the mechanisms by which fungi can sequester certain heavy metals is synthesizing stress proteins. The aim of this study is to investigate the production of metallothioneins in Aspergillus oryzae and Aspergillus clavatus exposed to environmentally relevant concentrations of Cd, Cu, Fe, and Zn at neutral, alkaline, and acidic pH conditions within 10 days. We determined the concentrations of these heavy metals in certain watercourses representing Behira and Giza governorates; also, we identified the most prevalent fungal species. We carried out a statistical correlation between different heavy metals and the isolated fungi. Then, in the laboratory, we exposed two of the most prevalent fungal species to the environmentally detected concentrations of the heavy metals and their doubles. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that in A. oryzae, the metallothionein bands appeared in neutral medium containing Cd and Cu and in alkaline medium containing Cd and Zn, while in A. clavatus, no metallothionein bands appeared at all. In conclusion, metallothionein is a good indicator of pollution with Cd, Cu, and Zn in Aspergillus oryzae, and pH plays a central role in metallothionein production.

Metallothionein production is a common tolerance mechanism in four species growing in polluted Cu mining areas in Peru

Cu pollution is a problem in mining areas in Peru. Here we evaluate the phytoextraction capacity, physiological and proteomic responses of four species growing in copper-contaminated areas in Arequipa, Peru. The plants used in the experiments were obtained by collecting seedlings (Tessaria integrifolia, Bacharis salicifolia), rhizomes (Eleocharis montevidensis) and seeds (Chenopodium murale) along a polluted river. They were exposed to solutions containing 2, 4, 8, 16 and 32 mg Cu L-1 during 20 days. Growth was affected in a concentration-dependent way. According to the tolerance index, B. salicifolia and C. murale were the most sensitive species, but with greater Cu phytoextraction capacity and accumulation in the biomass. The content and ratio of photosynthetic pigments changed differently for each specie and carotenoids level were less affected than chlorophyll. Cu also induced changes in the protein and sugar contents. Antioxidant enzyme activities (catalase and superoxide dismutase) increased with a decrease in the malondialdehyde. There were marked changes in the protein 2D-PAGE profiles with an increase in the abundance of metallothioneins (MT) of class II type I and II. Our results suggest that these species can grow in Cu polluted areas because they developed multiple tolerance mechanisms, such as and MTs production seems a important one.

Nrf2 deficiency aggravates the kidney injury induced by subacute cadmium exposure in mice.

Cadmium (Cd) is a heavy metal pollutant that adversely effects the kidney. Oxidative stress and inflammation are likely major mechanisms of Cd-induced kidney injury. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is crucial in regulating antioxidant and inflammatory responses. To investigate the role of Nrf2 in the development of subacute Cd-induced renal injury, we utilized Nrf2 knockout (Nrf2-KO) and control mice (Nrf2-WT) which were given cadmium chloride (CdCl2, 1 or 2mg/kg i.p.) once daily for 7days. While subacute CdCl2 exposure induced kidney injury in a dose-dependent manner, after the higher Cd dosage exposure, Nrf2-KO mice showed elevated blood urea nitrogen (BUN) and urinary neutrophil gelatinase-associated lipocalin (NGAL) levels compared to control. In line with the findings, the renal tubule injury caused by 2mg Cd/kg, but not lower dosage, in Nrf2-KO mice determined by Periodic acid-Schiff staining was more serious than that in control mice. Further mechanistic studies showed that Nrf2-KO mice had more apoptotic cells and severe oxidative stress and inflammation in the renal tubules in response to Cd exposures. Although there were no significant differences in Cd contents of tissues between Cd-exposed Nrf2-WT and Nrf2-KO mice, the mRNA expression of Nrf2 downstream genes, including heme oxygenase 1 and metallothionein 1, were significantly less induced by Cd exposures in the kidney of Nrf2-KO compared with Nrf2-WT mice. In conclusion, Nrf2-deficient mice are more sensitive to kidney injury induced by subacute Cd exposure due to a muted antioxidant response, as well as a likely diminished production of specific Cd detoxification metallothioneins.

Metallothionein dependent-detoxification of heavy metals in the agricultural field soil of industrial area: Earthworm as field experimental model system

Earthworms are known to reclaim soil contamination and maintain soil health. In the present study, the concentration of DTPA extractable heavy metals, Cd, Cu, Cr, Pb, and Zn in vermicasts and tissues of the earthworms (anecic: Lampito mauritii; epigeic: Drawida sulcata) collected from the soils of four different industrial sites, Site-I (Sago industry), Site-II (Chemplast industry), Site-III (Dairy industry) and Site-IV (Dye industry) have been studied. The heavy metals in industrial soils recorded were 0.01–326.42 mg kg−1 with higher Cu, Cr, and Zn contents while the vermicasts showed lower heavy metal loads with improved physicochemical properties and elevated humic substances. The higher humic substances dramatically decreased the heavy metals in the soil. The bioaccumulation factors of heavy metals (mg kg−1) are in the order: Zn (54.50) > Cu (17.43) > Cr (4.54) > Pb (2.24) > Cd (2.12). The greatest amount of metallothionein protein (nmol g−1) was recorded in earthworms from Site-IV (386.76) followed by Site-III (322.14), Site-II (245.82), and Site-I (232.21). Drawida sulcata can produce a considerable amount of metallothionein protein than Lampito mauritii as the metallothionein production is dependent upon the presence of pollutants. The molecular docking analysis indicates a binding score of 980 for Cd, Cr and Cu, and 372 for Zn. Pb may bind with a non-metallothionein protein of earthworms and bio-accumulated in the internal chloragogenous tissues. Metallothionein neutralizes the metal toxicity and controls the ingestion of essential elements.

Environment-friendly management of textile mill wastewater sludge using epigeic earthworms: Bioaccumulation of heavy metals and metallothionein production

In the present study, Eudrilus eugeniae and Perionyx excavatus were used for vermistabilization of textile mill sludge in different combinations with cowdung for 60 days. A higher percentage of metal removal was observed in earthworm treated mixtures for cadmium (54.5%) followed by copper (36.0%), chromium (37.0%) and zinc (35.9%). Vermistabilized textile mill sludge + cowdung (1:1) showed a maximum percentage increase in total NPK, a significant (P < 0.05) increase in bacteria, fungi, and actinomycetes with a better earthworm survival rate. A higher amount of metallothionein protein was produced by E. eugeniae than P. excavatus. Further, 100% textile mill sludge showed a number of histological abnormalities like degeneration of cells, cellular debris, and uneven cellular compartmentation while textile mill sludge with cowdung showed normal earthworm histology. Results suggest that textile mill sludge + cowdung (1:1) combination is suitable for vermistabilization of textile mill sludge.

Polysaccharide from the Seeds of Plantago asiatica L. Protect Against Lipopolysaccharide-Induced Liver Injury.

Previous studies have proven that polysaccharide obtained from the seeds of Plantago asiatica L. (PLCP) could induce maturation of murine dendritic cells, promote defecation, and possess antioxidant activity in vitro. However, the effect of PLCP on lipopolysaccharide (LPS)-induced liver injury in mice has been rarely reported. In this study, we investigated the anti-inflammatory effect of PLCP on LPS-induced liver injury. Mice were pretreated orally with different dose of PLCP for 3 weeks. On day 22, they were injected intraperitoneally with LPS and sacrificed 12 h later. The results showed that PLCP inhibited the excessive production of tumor necrosis factor-α, interleukin (IL)-6, IL-10, IL-2, and IL-1β in mouse serum and liver. PLCP also improved glutathione peroxidase and total antioxidant capacity activities in mouse liver. In addition, PLCP inhibited nitric oxide, inducible nitric oxide synthase, and cyclooxygenase-2 expression, and increased metallothionein production in mouse liver. Consequently, PLCP may possess protective effects on inflammatory associated liver injury.

Insights into the heavy metal-induced immunotoxic and genotoxic alterations as health indicators of Clarias gariepinus inhabiting a rivulet

There is a dire need to assess the quality of fishes transported for human consumption as lately, their health is challenged because of anthropogenic activities. Heavy metals with a long environmental persistence are toxic to fishes and the humans. The study was conducted to evaluate the impact of heavy metals on Clarias gariepinus inhabiting popular Ganges rivulet at Narora (28.18° E, 78.39° N). The limnological values deviated from the international Standards (USEPA, WHO). Higher total dissolved solids (859 mg/L), total suspended solids (406 mg/L), low dissolved oxygen (5.60 mg/L), and pH (5.21) indicated the presence of contaminants. Heavy metals estimated followed the order Cd > Ni > Cu > Cr. Serum enzymes (hepatic and renal markers) viz., aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were higher than the normal, whereas, creatine kinase (CK) was considerably low in both male and female fish. Stress induced was marked by elevation in cortisol and glucose. This had its impact on hematological parameters as well, as a decline in Total leucocyte count (TLC) & mean corpuscular volume (MCV) and increase in Mean cell hemoglobin (MCH) was observed. Erythrocytes also showed altered morphology. Marked histopathological alterations were observed in all immune organs (head-kidney, liver, spleen, thymus). Oxidative stress induced by heavy metals leads to the production of metal scavenging protein metallothionein (MT) and glutathione peroxidase (GPX). Maximum fold change in metallothionein (MT) gene expression was observed in the liver, followed by spleen, thymus, blood, and head-kidney. Glutathione peroxidase (GPX) gene expression was highest in the liver, followed by thymus, spleen, blood, and head-kidney. The gene expression studies further validated the increased level of heavy metals as potent contaminants of water and the non-condusive abiotic factors.

Histoplasma Responses to Nutritional Immunity Imposed by Macrophage Activation.

The fungal pathogen Histoplasma capsulatum resides within the phagosome of host phagocytic cells. Within this intracellular compartment, Histoplasma yeast replication requires the acquisition of several essential nutrients, including metal ions. Recent work has shown that while iron, zinc, and copper are sufficiently abundant in resting macrophages, cytokine activation of these host cells causes restriction of these metals from intracellular yeasts as a form of nutritional immunity. Faced with limited iron availability in the phagosome following macrophage activation by IFN-γ, Histoplasma yeasts secrete iron-scavenging siderophores and employ multiple strategies for reduction of ferric iron to the more physiologically useful ferrous form. IFN-γ activation of macrophages also limits availability of copper in the phagosome, forcing Histoplasma reliance on the high affinity Ctr3 copper importer for copper acquisition. GM-CSF activation stimulates macrophage production of zinc-chelating metallothioneins and zinc transporters to sequester zinc from Histoplasma yeasts. In response, Histoplasma yeasts express the Zrt2 zinc importer. These findings highlight the dynamics of phagosomal metal ion concentrations in host-pathogen interactions and explain one mechanism by which macrophages become a less permissive environment for Histoplasma replication with the onset of adaptive immunity.

Sensitivity to cadmium of the endangered freshwater pearl mussel Margaritifera margaritifera from the Dronne River (France): experimental exposure.

Margaritifera margaritifera is a critically endangered species in Europe. Among the causes explaining its decline, metal pollution had never been deeply studied. Thus, an ecotoxicological investigation was developed on this species which comes from the Dronne River (South-West of France). Cadmium (Cd) exposure of mussels at 2 and 5μg/L for 7days was conducted to test their vulnerability to this metal, and also the potential endocrine disruption power of Cd. Morphometric analyses, gonad histological observations, metal bioaccumulation, metallothionein (MTs) production, measures of malondialdehyde (MDA), and finally quantitative relative expression analysis of genes involved in various metabolic functions were performed.The main results showed Cd accumulation increasing in a dose-dependent manner, especially in the gills. The same trend was observed for gene expression relative to oxidative stress. Histological analysis of the gonads highlighted a predominance of hermaphrodite individuals, but after 7days of exposure to Cd, the percentage of female was largely increased compared with controls, from 17 to 33%. These results demonstrate the endocrine disruption effect of Cd on freshwater pearl mussels.The pearl mussel Margaritifera margaritifera is sensitive to cadmium since the metallothioneins are poorly induced, gene expression reveals oxidative stress, and gonads tend to be feminized.

Sex-dependent expression of metallothioneins MT1 and MT2 and concentrations of trace elements in rat liver and kidney tissues: Effect of gonadectomy

Metallothioneins (MTs) exhibit binding affinity for several essential and toxic trace elements. Previous studies in rodents indicated sex differences in the hepatic and renal expression of MTs and concentrations of various elements. The mechanism responsible for these differences has not been resolved. Here, in the liver and kidney tissues of sham-operated and gonadectomized male and female rats we determined the expression of MT1 and MT2 (MT1&2) mRNA by RT-PCR, abundance of MT1&2 proteins by Western blotting and immunocytochemistry, concentrations of essential (Fe, Zn, Cu, Co) and toxic (Cd, Hg, Pb) elements by ICP-MS, and oxidative status parameters (SOD, GPx, MDA, GSH) by biochemical methods. In both organs, the expression of MT1&2 mRNA and MT1&2 proteins was female-dominant, upregulated by castration, and downregulated by ovariectomy. Concentrations of Fe in the liver and Co in the kidneys followed the same pattern. Most other elements (Zn, Cu, Cd, Hg) exhibited female- or male-dominant sex differences, affected by gonadectomy in one or both organs. Pb was sex- and gonadectomy-unaffected. GPx and MDA were elevated and associated with the highest concentrations of Fe only in the female liver. We conclude that the sex-dependent expression of MT1&2 mRNA and proteins in the rat liver and kidneys may include different mechanisms. In the liver, the female-dominant tissue concentrations of Fe may generate oxidative stress which is a potent enhancer of MTs production, whereas in kidneys, the female-dominant expression of MTs may be unrelated to Fe-mediated oxidative stress.

Understanding the phyto-interaction of heavy metal oxide bulk and nanoparticles: evaluation of seed germination, growth, bioaccumulation, and metallothionein production.

The fast-growing use of nano-based products without proper care has led to a major public health concern. Nanomaterials contaminating the environment pose serious threat to the productivity of plants and via food chain to human health. Realizing these, four vegetable crops, radish, cucumber, tomato, and alfalfa, were exposed to varying concentrations of heavy metal oxide (TiO2, ZnO, Al2O3 and CuO) submicron or bulk (BPs) and nanoparticles (NPs) to assess their impact on relative seed germination (RSG), seed surface adsorption, root/shoot tolerance index (RTI/STI), bioaccumulation, and metallothioneins (MTs) production. The results revealed a clear inhibition of RSG, RTI, and STI, which, however, varied between species of metal-specific nanoparticles and plants. SEM and EDX analyses showed significant adsorption of MONP agglomerates on seed surfaces. The concentration of metals detected by EDX differed among vegetables. Among the metals, Al, Cu, Ti, and Zn were found maximum in alfalfa (12.46%), tomato (23.2%), cucumber (6.32%) and radish (21.74%). Of the four metal oxides, ZnO was found most inhibitory to all vegetables and was followed by CuO. The absorption/accumulation of undesirable levels of MONPs in seeds and seedlings differed with variation in dose rates, and was found to be maximum (1748–2254 μg g−1 dry weight) in ZnO-NPs application. Among MONPs, the uptake of TiO2 was minimum (2 to 140 μg g−1) in radish seedlings. The concentration of MTs induced by ZnO-NPs, ZnO-BPs, and CuO-NPs ranged between 52 and 136 μ mol MTs g−1 FW in vegetal organs. Conclusively, the present findings indicated that both the nanosize and chemical composition of MONPs are equally dangerous for vegetable production. Hence, the accumulation of MONPs, specifically ZnO and CuO, in edible plant organs in reasonable amounts poses a potential environmental risk which, however, requires urgent attention to circumvent such toxic problems.