μM Cd Research Articles

Cadmium alters the cellular metabolome of human ovarian granulosa cells

Cadmium (Cd) is a toxic heavy metal that has been extensively implicated in disordered folliculogenesis, but the mechanisms underlying the ovarian toxicity of Cd remain to be explored fully. Granulosa cells are key players in ovarian follicular development and are the primary cells affected by Cd exposure-induced damage and dysfunction. In this study, we investigated how various levels of exposure of Cd (3 and 10 μM) to human granulosa cells (KGN cells) impacted the metabolism of the KGN cells utilizing a non-targeted metabolomics methodology. In vitro cell experiments revealed that Cd exposure dose-dependently diminished the viability of KGN cells. Metabolomics analysis revealed the presence of 296 (182 elevated and 114 reduced) and 397 (244 elevated and 153 reduced) differentially expressed metabolites after exposure to 3 and 10 μM, respectively. Cd exposure was found to significantly enrich nucleotide metabolism, sphingolipid metabolism, and ABC transporters in both groups. Although amino acid metabolic pathways exhibited significant enrichment across all groups, only glutathione, cysteine, and methionine metabolism were notably enriched in KGN cells exposed to 3 μM Cd, while glutathione and tryptophan metabolism were significantly enriched in the 10 μM Cd exposure cohort. The outcomes of this study provide mechanistic clues for elucidating Cd’s cytotoxic impact on granulosa cells, and deepen our understanding of the ovarian toxicity of Cd.

The paradoxical effects of beneficial bacteria on Solanum lycopersicum under Cd stress.

This study investigated the complex interactions between a novel consortium and tomato seedlings under cadmium (Cd) stress. The consortium consists of two bacteria, Pseudomonas sp. HS4 and Paenarthrobacter sp. AS8, both with proven plant growth-promoting (PGP) properties, isolated from Cd hyperaccumulators. Our research highlights the paradoxical effects of these bacteria, revealing their dual role in reducing Cd uptake while simultaneously inducing oxidative stress in plants. Hydroponic experiments showed that the consortium reduced Cd accumulation in tomato shoots by 52% compared to uninoculated controls. However, this reduction was accompanied by decreased plant biomass and increased oxidative stress, with malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels up to 80% and 160% higher, respectively, in inoculated plants. Root H₂O₂ production increased by 38% under 50 μM Cd without a corresponding rise in catalase (CAT) activity. Despite Cd exposure, the consortium promoted chlorophyll and carotenoid synthesis, restoring pigment levels to those of unstressed controls. Gene expression analysis revealed a complex impact on stress responses, with inoculation suppressing Sl1 gene expression in roots and upregulating the oxidative stress-related GR-1 gene in shoots. These findings highlight the complex and multifaceted relationship between beneficial bacteria and plant fitness under heavy metal stress, with significant implications for sustainable agriculture. The study raises new questions regarding the broader physiological and ecological impacts of applying hyperaccumulator-associated bacteria in crop management, emphasizing the necessity for deeper mechanistic insights into these interactions to fully harness their potential in improving crop resilience and productivity.

Activating PPARβ/δ-Mediated Fatty Acid β-Oxidation Mitigates Mitochondrial Dysfunction Co-induced by Environmentally Relevant Levels of Molybdenum and Cadmium in Duck Kidneys.

Cadmium (Cd) and high molybdenum (Mo) pose deleterious effects on health. Prior studies have indicated that exposure to Mo and Cd leads to damage in duck kidneys, but limited studies have explored this damage from the perspective of fatty acid metabolism. In this study, 40 healthy 8-day-old ducks were randomly assigned to four groups and fed a basic diet containing Cd (4mg/kg Cd) or Mo (100mg/kg Mo) or both. Kidney tissues were harvested on the 16th week. Results demonstrated that Cd and/or Mo inhibited mitochondrial fatty acid β-oxidation and disrupted mitochondrial dynamics, along with significant suppression of peroxisome proliferator-activated receptor β/δ (PPARβ/δ) protein in duck kidneys. In vitro study, duck renal tubular epithelial cells were exposed for 12h to either Mo (480μM Mo), Cd (2.5μM Cd), and GW0742 (0.3μM, a potent agonist of PPARβ/δ) alone or in combination. The results demonstrated that Cd and/or Mo led to marked fatty acid oxidation deficiency and mitochondrial dysfunction and that PPARβ/δ protein was involved in the process. Altogether, this study found that activating PPARβ/δ-mediated fatty acid β-oxidation mitigates mitochondrial dysfunction co-induced by Mo and Cd in duck kidneys.

Effect of Ag+ and Cd2+ Elicitation on Polyphenol Production in Shoot Culture of Dracocephalum ruyschiana L.

Abiotic elicitation with heavy metals has demonstrated considerable potential to stimulate the production of industrially important secondary metabolites in plant in vitro cultures. The present study investigates the effect of exogenous silver nitrate and cadmium chloride supplementation on flavonoid and phenolic acid production, as well as other indicators of oxidative stress, in shoot cultures of Dracocephalum ruyschiana L. Owing to the presence of bioactive polyphenolic compounds, this Mongolian medicinal plant is traditionally used as an anti-inflammatory, antibacterial and antipyretic agent. The shoots were cultured for three weeks, and then, cadmium (Cd2+) and silver (Ag+) ions (50 or 100 µM) were added to the medium. The maximum proliferation rate was observed in the presence of 100 µM Ag+ (almost 5), the highest chlorophyll content in the presence of 100 µM Cd2+ (0.6 mg/g FW) and the highest biomass was observed with both these treatments (73.4-75.7 g FW and 7.53-7.72 g DW). UPLC-PDA-ESI-MS analysis revealed four phenolic acids and five flavonoid derivatives in the hydromethanolic extract of D. ruyschiana shoots. All treatments stimulated the production of rosmarinic acid (RA), which was the dominant compound in the analyzed culture; the highest level of RA, i.e., about three times higher than the control, was noted in shoots exposed to 50 µM Cd2+ (14.72 mg/g DW), whereas the level of most flavonoids in the culture increased most significantly when exposed to Cd2+ at a concentration of 100 µM. Moreover, the shoots grown in the presence of 100 µM Cd2+ exhibited significantly higher antioxidant potential in comparison to the control. Our findings indicate that heavy metals are able to stimulate phenolic compound biosynthesis in Dracocephalum shoots without any negative impact on their growth. These results could be of significant importance for the medical, nutraceutical and agronomic industries.

Alterations in nitrogen metabolism caused by heavy metals in the acid-tolerant microalga Coccomyxa onubensis

The microalga Coccomyxa onubensis is an extremophile microorganism with a unique ecosystem (Río Tinto, Huelva, Spain) that contains high amounts of contaminants, including heavy metals, sulphates, and nitrates, in acidic environments (pH 2.5). The current work presents an evaluation of the capacity of Coccomyxa onubensis to assimilate different nitrogen sources under Cu2+, Cd2+, AsO33−, AsO43− and Hg2+ stress, and the metabolic implications of these stressors. The results showed that ammonium consumption was less affected than nitrate consumption when microalgae were cultivated with heavy metals (except cadmium). The activities of enzymes involved in nitrogen metabolism, such as nitrite reductase (NiR; EC:1.7.7.1), glutamine synthetase (GS; EC:6.3.2.1) and glutamate dehydrogenase (GDH; EC:1.4.1.2) were characterised to determine the Michaelis-Menten constant (Km) and optimal temperature and pH values, being 45, 40 and 60 °C and pH values of 7.5, 6.0 and 9.0 for NiR, GS, and GDH, respectively. The effects of different heavy metals on these enzymes were assessed at multiple levels, and the results showed that the enzymatic activity of NiR was downregulated, specially under copper stress, maintaining 23 % of control NiR activity at 2 mM Cu2+. The enzymatic activity of GS was upregulated at low concentrations under cadmium and mercury stress (115–120 % of control cultures GS activity at 25 μM Cd2+ and 50 nM Hg2+, respectively) and downregulated at high concentrations of these elements. GDH activity was upregulated in the presence of Cu2+, Cd2+, and Hg2+, with increases up to 192, 155 and 154 % at 1 mM Cu2+, 300 μM Cd2+, and 250 nM Hg2+, respectively. These results provide a better explanation of the effects of heavy metal stress on N metabolism in Coccomyxa onubensis, which may be used as a model eukaryotic organism of the Tinto River acidophilic ecosystem.

Invitro evaluation of interactions between cylindrospermopsin and water contaminants, arsenic and cadmium, in two human immune cell lines

Cylindrospermopsin (CYN), a cyanotoxin with worldwide distribution, is gaining increased attention due to its bioaccumulation potential and toxicological effects. Previous research suggests that CYN may interact with other environmental contaminants, potentially amplifying its toxicity. To address this concern, the present study investigated the combined effects of CYN with arsenic (As) and cadmium (Cd) on human immune cell lines, Jurkat and THP-1. Cytotoxicity tests showed that As and Cd significantly decreased the viability of both cell lines after 24 and 48 h of exposure. The EC50 (24 h) values for Jurkat cells were 13.15 ± 1.97 (As) and 36.92 ± 3.77 μM (Cd), respectively, while for THP-1, the EC50 (24 h) values were 46.48 ± 0.17 for As and 55.09 ± 4.98 μM for Cd. Furthermore, individual contaminants and their mixtures with CYN impaired monocyte differentiation into macrophages. The effect on mRNA expression of some cytokines (TNF-α, INF-γ, IL-2, IL-6 and IL-8) was also assessed. In the Jurkat cell line, As upregulated IL-8 expression while Cd increased the expression of all interleukins. Exposure to binary combinations (CYN + As, and CYN + Cd) increased IL-2 and INF-γ expression. In THP-1 cells, As elevated IL-8 and INF-γ expression, whereas Cd caused an increase in TNF-α and INF-γ expression. Exposure to CYN + As up-regulated IL-8 and INF-γ expression, while the CYN + Cd combination down-regulated TNF-α expression. These findings highlight the complex interactions between contaminants, emphasizing the need for evaluating combined effects in risk assessments.

Physiological and biochemical responses in a cadmium accumulator of traditional Chinese medicine Ligusticum sinense cv. Chuanxiong under cadmium condition

Ligusticum sinense cv. Chuanxiong (L. Chuanxiong), one of the widely used traditional Chinese medicines (TCM), is currently facing the problem of excessive cadmium (Cd) content. This problem has significantly affected the quality and safety of L. Chuanxiong and become a vital factor restricting its clinical application and international trade development. Currently, to solve the problem of excessive Cd, it is essential to research the response mechanisms of L. Chuanxiong to Cd stress. However, there are few reports on its physiological and biochemical responses under Cd stress. In this study, we conducted the hydroponic experiment under 25 μM Cd stress, based on the Cd content of the genuine producing areas soil. The results showed that 25 μM Cd stress not only had no significant inhibitory effect on the growth of L. Chuanxiong seedlings but also significantly increased the chlorophyll a content (11.79%) and root activity (51.82%) compared with that of the control, which might be a hormesis effect. Further results showed that the absorption and assimilation of NH4+ increased in seedlings under 25 μM Cd stress, which was associated with high photosynthetic pigments. Here, we initially hypothesized and confirmed that Cd exceedance in the root system of L. Chuanxiong was due to the thickening of the root cell wall, changes in the content of the cell wall components, and chelation of Cd by GSH. There was an increase in cell wall thickness (57.64 %) and a significant increase in cellulose (25.48%) content of roots under 25 μM Cd stress. In addition, L. Chuanxiong reduced oxidative stress caused by 25 μM Cd stress mainly through the GSH/GSSG cycle. Among them, GSH-Px (48.26%) and GR (42.64%) activities were significantly increased, thereby maintaining a high GSH/GSSG ratio. This study preliminarily reveals the response of L. Chuanxiong to Cd stress and the mechanism of Cd enrichment. It provides a theoretical basis for solving the problem of Cd excessive in L. Chuanxiong.Graphical Physiological and biochemical mechanisms of L. Chuanxiong seedlings under Cd stress.

An Automated Cell-Free Workflow for Transcription Factor Engineering.

The design and optimization of metabolic pathways, genetic systems, and engineered proteins rely on high-throughput assays to streamline design-build-test-learn cycles. However, assay development is a time-consuming and laborious process. Here, we create a generalizable approach for the tailored optimization of automated cell-free gene expression (CFE)-based workflows, which offers distinct advantages over in vivo assays in reaction flexibility, control, and time to data. Centered around designing highly accurate and precise transfers on the Echo Acoustic Liquid Handler, we introduce pilot assays and validation strategies for each stage of protocol development. We then demonstrate the efficacy of our platform by engineering transcription factor-based biosensors. As a model, we rapidly generate and assay libraries of 127 MerR and 134 CadR transcription factor variants in 3682 unique CFE reactions in less than 48 h to improve limit of detection, selectivity, and dynamic range for mercury and cadmium detection. This was achieved by assessing a panel of ligand conditions for sensitivity (to 0.1, 1, 10 μM Hg and 0, 1, 10, 100 μM Cd for MerR and CadR, respectively) and selectivity (against Ag, As, Cd, Co, Cu, Hg, Ni, Pb, and Zn). We anticipate that our Echo-based, cell-free approach can be used to accelerate multiple design workflows in synthetic biology.

How does NaCl enhance Cd tolerance in Inula crithmoides L? Insights into Cd uptake, compartmentalization, and chelation

This study investigated the effect of NaCl on the uptake, translocation, compartmentalization, and chelation of cadmium (Cd) in the halophyte Inula crithmoides. Seedlings were subjected hydroponically for 21 days to 25 and 50 μM Cd applied alone or combined with 100 mM NaCl. Findings revealed that, Cd alone induced intense chlorosis and necrosis and altered plant development resulting in diminished biomass production. However, NaCl alleviated Cd-induced toxicity by increasing biomass accumulation, associated with restoration of photosynthesis activity. At the level of whole plant, NaCl reduced Cd concentration in different organs as well as its translocation toward the shoots. At the cellular level, Na Cl changed the cell-compartmentalization of Cd in the shoots and roots by inducing a preferential accumulation into the soluble fraction (vacuole). NaCl increased the chelation of Cd to chloride and nitrate. As compared to Cd alone, salt addition to Cd-treated plants enhanced significantly succinic acid concentration in the leaves suggesting a possible role of this acid in Cd-chelation. Globally, NaCl alleviated Cd-induced phytotoxicity in this halophyte by reducing Cd absorption, translocation and increased Cd fixation to organic acids as well as through the changes in Cd2+ cell compartmentalization. Obtained data suggested that this fast growing halophyte could be used to rehabilitate Cd polluted saline soils.

Salidroside prevents cadmium chloride-induced DNA damage in human fetal lung fibroblasts

BackgroundCadmium (Cd) is an environmental pollutant and a heavy metal known for its genotoxic effects, which can lead to cancer and other related diseases. Preventing Cd-induced genotoxicity is crucial; however, there is limited research on this topic. Salidroside (SAL), a phenylpropanoid glycoside isolated from Rhodiola rosea L., is a popular medicinal compound with several health benefits. Nevertheless, its therapeutic effect on Cd-induced genotoxicity remains unexplored. MethodsHuman fetal lung fibroblasts were treated with 20 μM Cd2+ (CdCl2) for 12 h and 5–20 μM SAL was used to test the anti-DNA damage effect. DNA damage was evaluated using γH2AX expression and the alkaline comet assay. Intracellular reactive oxygen species (ROS) levels were measured using flow cytometry. ResultsExposure to 20 μM Cd2+ for 12 h induced significant DNA damage in human fetal lung fibroblasts, and this effect was notably attenuated by SAL treatment. SAL treatment did not decrease ROS levels in cells treated with Cd2+. ConclusionSAL effectively prevented Cd2+-induced DNA damage in human fetal lung fibroblasts. However, the underlying mechanism requires further investigation.

Low concentrations of methyl jasmonate promote plant growth and mitigate Cd toxicity in Cosmos bipinnatus

Cadmium (Cd) is a biologically non-essential heavy metal, a major soil pollutant, and extremely harmful to plants. The phytohormone methyl jasmonate (MeJA) plays an important role in plant heavy-metal resistance. However, the understanding of the effects of MeJA supply level on alleviating Cd toxicity in plants is limited. Here, we investigated how MeJA regulated the development of physiological processes and cell wall modification in Cosmos bipinnatus. We found that low concentrations of MeJA increased the dry weight of seedlings under 120 µM Cd stress by reducing the transport of Cd from roots to shoots. Moreover, a threshold concentration of exogenous MeJA increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in plant roots, the concentration of Cd in the root cell wall, and the contents of pectin and hemicellulose 1 polysaccharides, through converting Cd into pectin-bound forms. These results suggested that MeJA mitigated Cd toxicity by modulating root cell wall polysaccharide and functional group composition, especially through pectin polysaccharides binding to Cd, with effects on Cd transport capacity, specific chemical forms of Cd, and homeostatic antioxidant systems in C. bipinnatus.

Multivariate characterization of salicylic acid and potassium induced physio-biochemical and phytoremediation responses in quinoa exposed to lead and cadmium contamination

The levels of soils pollutants such as lead (Pb) and cadmium (Cd) have significantly increased recently resulting in ecological disturbances and threatening crop production. Various amendments have been employed to enhance the tolerance of crops to withstand Cd and Pb stresses. However, the role of combined application of potassium (K) and of salicylic acid (SA) for Cd and Pb stress mitigation and phytoremediation by quinoa (Chenopodium quinoa Willd) has not been comprehended well. In the present study, the effect of 10 mM K and 0.1 mM SA was tested on the quinoa plants subjected to 250 μM Pb and/or 100 μM Cd. The Pb and Cd treatments were applied separately or together. Phytotoxicity induced by Pb and Cd resulted in drastic decrease (>60%) in chlorophyll contents, stomatal conductance, and plant biomass. The collective treatment of Pb and Cd induced an increase in the concentration of hydrogen peroxide (13-fold) and lipid peroxidation (16-fold) that resulted in a 61% reduction in membrane stability. The application of 10 mM K and/or 0.1 mM SA was remarkable in mitigating the adverse effect of Pb and Cd. The reduction in plant biomass was 17% when 10 mM K and 0.1 mM SA were applied together under the combined treatment of both the metals. The simultaneous application of K and SA effectively mitigated oxidative stress by enhancing the activities of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase by 12, 10, 7 and 10-folds respectively. The positive effect of K and SA on these attributes resulted in a remarkable reduction in metal accumulation and translocation and lipid peroxidation. The stressed plants supplemented with K and SA exhibited a significant improvement in the membrane stability index, chlorophyll content, and stomatal conductance. This study concluded that the combined application of K and SA could be a good approach for reducing Pb and Cd phytotoxicity in quinoa and enhancing their phytostabilization potential in the contaminated soils.

Effect of Mn on Cd2+ uptake by protoplasts of the Cd/Mn hyperaccumulator Celosia argentea Linn. differs by treatment method

The effect mechanism of Mn on Cd uptake by Celosia argentea was investigated via a series of hydroponics experiments. The results showed that different manganese treatments had different effects on Cd uptake by C. argentea. Mn pretreatment increased Cd uptake by root protoplasts at Cd concentrations (4 and 6 μM). Protoplasts reached peak Cd uptake rate at 6 μM Cd and 25 °C, with 67.71 ± 0.13 μM h−1 mL−1 in the control, and 77.99 ± 0.49 μM h−1 mL−1 in the 50 μM Mn pretreatment group. However, simultaneous treatment with Cd and Mn reduced the Cd2+ uptake by root protoplasts. This discrepancy may be attributed to the fact that cadmium and manganese share some transporters in root cells. The transcriptome analysis in roots revealed that ten genes (including ABCC, ABCA, ABCG, ABCB, ABC1, BZIP19, and ZIP5) were significantly upregulated in response to Mn stress (p < 0.05). These genes regulate the expression of transporters belonging to the ABC, and ZIP families, which may be involved in Cd uptake by root cells of C. argentea. Mn pretreatment upregulates the expression of Mn/Cd transporters, enhancing Cd uptake by root protoplasts. For the simultaneous treatment of Cd and Mn, inhibition of Cd uptake was due to the competition of the same transporters. These findings provide helpful insights for understanding the mechanism of Mn and Cd uptake in hyperaccumulators and give implications to improve the phytoremediation of Cd-contaminated soil by C. argentea.

How does silicon alleviate Cd-induced phytotoxicity in barley, Hordeum vulgare L.?

Toxic heavy metal accumulation in edible plants has become a problem worth worrying about for human health. Cadmium is one of the most toxic metals presenting high bioavailability in the environment. The main route of transfer of Cd to humans is the consumption of contaminated food which suggests that reducing of Cd absorption by plants could reduce this risk. In this context, it was suggested that silicon supply would be able to limit the transfer of Cd to the plants. Thus, this work evaluated the effects of 0.5 mM Si on Cd absorption and accumulation in barley (Hordeum vulgare L.). Plants were grown hydroponically for 21 days in the presence of 0 and 15 μM Cd2+ combined or not with 0.5 mM Si. Analyses were related to growth and photosynthesis parameters, Cd accumulation in organs and Cd subcellular distribution in the shoots. Results showed that, under Cd alone, plants showed severe toxicity symptoms as chlorosis and necrosis and produced significantly less biomass as compared to control. 0.5 mM Si in the medium culture significantly reduced Cd-induced toxicity by mitigating symptoms and restoring growth, photosynthesis, and nutrition. Si also induced a significant reduction of Cd concentration in plants and changed its sub-cellular compartmentalization by enhancing fixation to cell walls and reducing the Cd concentration in the cytoplasmic and organelles fractions. These data suggest that the application of Si could significantly increase Cd tolerance and reduce the risk of the Cd accumulation in edible plants.

P-104 Cytoprotective effect of melatonin in prepubertal Sertoli cells: role in cadmium-induced idiopathic male infertility

Abstract Study question Melatonin (MLT) is a cytoprotective agent holding potential to prevent cadmium (Cd) toxicity and its impact in testicular function and fertility. Summary answer MLT produced a potent cytoprotective effect in Sertoli cells (SCs) exposed to Cd-toxicity, reducing its H2O2 generation and reductive stress effects by modulation Nrf2 activity. What is known already MLT a hormonal substance exhibiting strong antioxidative and antiapoptotic properties, has been proved to hold great potential as cytoprotec tive agent in a range of tissues and cell models exposed to Cd toxicity, including the rat bone, ovaries, human MSC, and even mammalian testes. However, cellular and mechanistic aspects of this effect of MLT in testes remain poorly understood. Cd is a pro-oxidant heavy metal reported to interfere with testicular function and fertility. Both the toxicity of Cd and the cytoprotective function of MLT involve redox-dependent mechanisms with the activity of Nrf2 transcription factor as key player on the cellular stress response. Study design, size, duration Porcine pre-pubertal SCs were maintained at 37 °C in a 5% CO2 humidified atmosphere in the absence (unexposed-control group) or presence of 5 or 10µM CdCl2 (Sigma Chemical Co.) and/or 50nM MLT (Sigma-Aldrich) for 48h in HAMF12 (Euroclone) supplemented with 0.166nM retinoic acid (Sigma-Aldrich Co.) and 5/500ml of Insulin-Transferrin-Selenium (ITS) + Premix (Cat. No. 354352; Corning). Participants/materials, setting, methods After treatment the parameters investigated in the study were: a) SCs viability (MTT test); b) SCs functionality parameters AMH and inhibin B. (real-time PCR and ELISA analysis); c) Intracellular and extracellular ROS production ( with Amplex Red and DCFH-DA fluorescent probe respectively); d) Catalase enzyme activity (spectrophotometric assay procedure); e) Nrf2 and other transcription factors (by semi-quantitative microplate confocal microscopy analysis); f) Intracellular and extracellular levels of GSH and other thiols (by HPLC); g) c-Jun and ERK1/2 (Immunoblot). Main results and the role of chance MLT co-treatment significantly prevented the effects of Cd on cell viability and abnormal ROS production. The reduction of H2O2 efflux was very important and combined with an increased CAT activity that was demonstrated upon MLT treatment significantly in SCs exposed to 5μMCd. The co-treatment with MLT compared to Cd treatment, showed a trend toward a significant recovery of AMH and inhibin B gene expression and secretion levels, respectively, demonstrating the cytoprotective effect of MLT in SCs exposed to Cd toxicity at the functional level. In Cd-treated cells, MLT significantly reduced the expression and nuclear translocation of Nrf2 protein, and decreased GSTP induction. However, MLT reduced Cys uptake and stimulated GSH efflux when the cells were treated with 10 µM Cd, suggesting a specific role for the Nrf2-GSTP axis in the cytoprotective response to MLT of Cd-treated SCs. Finally MLT induced MAPK-ERK1-2 pathway and c-Jun transcription factor when the cells were treated with Cd. MLT is a cytoprotective agent in SCs exposed to Cd toxicity capable to restore cell viability and function. Its activity is associated with the modulation of Nrf2 and other stress response genes important in the control of thiols and H2O2 metabolism of SCs, including cJun and MAPKs. Limitations, reasons for caution Other ROS-scavenging genes other than CAT may have a role in the antioxidant response to MLT of SCs, such as superoxide dismutase, glutathione peroxidases, and peroxyredoxins that are worth investigating further. Wider implications of the findings The aspects that emerged from our study and, described for the first time in these cells, warrant further preclinical and clinical investigation holding potential in the treatment of Cd-induced testicular damage and fertility problems. Trial registration number Not applicable

Identification of genes involved in cadmium-ion tolerance in evolutionary Synechocystis sp. PCC 6803 tolerant to both cadmium and high light

Photosynthetic cyanobacteria have shown great potential as "autotrophic cell factories" for the synthesis of fuels and chemicals. However, poor tolerance to various environmental stressors like high light and heavy metals is an important factor limiting their economic viability. While numerous studies have focused on the tolerance mechanism of cyanobacteria to individual stressors, their response to simultaneous stresses remains to be recovered. To investigate the mechanism of cross tolerance to heavy metal Cd2+ and high light, the model cyanobacterium Synechocystis sp. PCC 6803 tolerant to both Cd2+ and high light was obtained via about 800 days’ cross-adaptive laboratory evolution. Three evolutionary strains capable of tolerating both 5.5 μM Cd2+ and 600 μmol photons m−2s−1 high light were successfully obtained, achieving about 83% enhancement of Cd2+ tolerance compared with the parent strain. The different response of parent and evolutionary strains to Cd2+ was elucidated via metabolomics. Further, a total of 15 genes that were mutated during evolution were identified by whole-genome re-sequencing. Finally, by single gene knockout and complementation analysis, four genes including ssl2615, sll1732, ssr1480 and sll1659 involved in the improvement of Cd2+ tolerance under high light condition were successfully identified. This work explored the tolerance mechanism of Synechocystis sp. PCC 6803 to cadmium under high light condition, and provided valuable reference for deciphering multi-tolerance mechanism of cyanobacteria in the future.

Silicon Dioxide Nanoparticles-Based Amelioration of Cd Toxicity by Regulating Antioxidant Activity and Photosynthetic Parameters in a Line Developed from Wild Rice.

An extremely hazardous heavy metal called cadmium (Cd) is frequently released into the soil, causing a considerable reduction in plant productivity and safety. In an effort to reduce the toxicity of Cd, silicon dioxide nanoparticles were chosen because of their capability to react with metallic substances and decrease their adsorption. This study examines the processes that underlie the stress caused by Cd and how SiO2NPs may be able to lessen it through modifying antioxidant defense, oxidative stress, and photosynthesis. A 100 μM concentration of Cd stress was applied to the hydroponically grown wild rice line, and 50 μM of silicon dioxide nanoparticles (SiO2NPs) was given. The study depicted that when 50 μM SiO2NPs was applied, there was a significant decrease in Cd uptake in both roots and shoots by 30.2% and 15.8% under 100 μM Cd stress, respectively. The results illustrated that Cd had a detrimental effect on carotenoid and chlorophyll levels and other growth-related traits. Additionally, it increased the levels of ROS in plants, which reduced the antioxidant capability by 18.8% (SOD), 39.2% (POD), 32.6% (CAT), and 25.01% (GR) in wild rice. Nevertheless, the addition of silicon dioxide nanoparticles reduced oxidative damage and the overall amount of Cd uptake, which lessened the toxicity caused by Cd. Reduced formation of reactive oxygen species (ROS), including MDA and H2O2, and an increased defense system of antioxidants in the plants provided evidence for this. Moreover, SiO2NPs enhanced the Cd resistance, upregulated the genes related to antioxidants and silicon, and reduced metal transporters' expression levels.

Acclimation of Primary Photosynthetic Reactions in the Cells of Chlamydomonas reinhardtii to Cadmium: Analysis of Cell Population Heterogeneity

The mechanisms of acclimation of primary photosynthetic reactions in the green microalgae Chlamydomonas reinhardtii to the toxic action of cadmium were investigated by analyzing the dynamics of distribution of key photosynthetic parameters in cell population. A synchronous culture of microalgae was incubated for 96 h in the presence of 25 μM Cd, and OJIP-transient curves of individual cells were recorded at different stages of incubation with the toxicant using an original microfluorometer. The analysis of OJIP-transient curves made it possible to determine distributions of key JIP-test parameters: FV/FM, ETO/ABS, RC/ABS, which represent photochemical activity of PS II, electron transport in PS II, and light absorption per active reaction center in PS II, respectively. Acclimation of primary photosynthetic reactions in microalgae to cadmium was accompanied by the appearance of two dominating cell fractions, which demonstrated the stable values of photosynthetic parameters when energy imbalance occurred due to the presence of the toxicant. The cells related to the first fraction retained moderate PS II activity by the effect of reduced PS II antenna size, while the cells of the second fraction showed low photochemical activity of PS II keeping antenna size similar to those of control cells.

In vitro selection and characterization of cadmium-tolerant calli of Tagetes erecta and Gomphrena globosa

Ornamental plants (OPs) are beneficial to remove, control and reduce heavy metals (HMs) in a process called 'phytoremediation'. This study evaluated the in vitro system-based phytoremediation properties of Tagetes erecta and Gomphrena globosa calli. Leaves from in vitro seed-grown T. erecta and G. globosa were used as an explant source for callus culture. Callus culture was found optimal in MS medium supplemented with 8 μM BAP + NAA for T. erecta and 2 μ M 2, 4-D for G. globosa. These plants were grown in their respective optimized (controlled) medium enriched with different amounts (50, 100, 150, 200, and 250 μM) of Cadmium (Cd) added in the form of Cadmium chloride (CdCl2). The in vitro calli developed were evaluated for Cd stress tolerance based on callus diameter, growth tolerance index (GTI) and catalase (CAT) activity. Over four weeks, the callus diameters of T. erecta and G. globosa grown in different concentrations of Cd had lower growth than that of the controlled one. On the other hand, the GTI measured were greatest at 150 μM of Cd for both T. erecta (130.95%) and G. globosa (149.32%) suggesting a potential Cd tolerance. However, the CAT activity in T. erecta callus increased with the Cd concentration peaking at 150 µM then started declining while G. globosa callus showed the highest CAT activity at 50 μM of Cd. Thus, T. erecta callus showed greater Cd tolerance with the prospect of utilizing it for phytoremediation. The study also suggests growing T. erecta at 150 μM Cd for tolerant calli.

Synergistic Effects of Exogenous Nutrient Ions on the Real-Time Cadmium Extraction by an Accumulator

Bidens tripartita L. is a cadmium (Cd) accumulator. However, the real-time influx or efflux of Cd2+ around its root apex has not yet been performed. The object of this experiment was to compare the roles of added ions in solution on dynamic Cd extraction by B. tripartita root tip. Quartz sand was used to grow the seedling of B. tripartite. The Cd concentrations of all samples were determined by using ICP-OES after digestion. The Cd2+ influx around the root apex was measured in vivo, i.e., using non-invasive micro-test technology (NMT). The results showed that the Cd2+ influx was found to be decreased by 35.9%, 43.7%, 20.6%, and 57.5% under 10 μM Cd combined with high content Ca2+, Mg2+, Fe3+, or K+ (16 mM, 8 mM, 0.5 mM, 18 mM, respectively), compared to that under 10 μM Cd stress. But Cd treatments with low content ions with 0.05 mM Fe3+ or 0.5 mM S increased the Cd2+ influx in roots by 20.5% and 34.6%, respectively. It was also found that Cd treatment with high concentrations of Ca2+ or K+ increased the shoot biomass of B. tripartita seedlings. Chl a and b contents were significantly decreased in the Cd treatments with low concentrations of Fe3+ or S compared to those under Cd stress alone, and the dehydrogenase activity of the roots decreased in the treatment of Cd with 0.05 mM Fe3+ or 0.5 mM S. Our results indicate that the addition of 0.05 mM Fe3+ or 0.5 mM S promoted Cd2+ influx and Cd uptake by B. tripartita. Unlike traditional measurement, the Cd2+ movements of three-dimensional space around the B. tripartita root tip had been performed by NMT. It was suggested that the effects of S and Fe3+ on the remediation potential of B. tripartita need to be further researched in the future. The results of this study provided a real-time and micro-dynamic theoretical basis for phytoremediation mechanisms.