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X-ray absorption spectroscopy evidence of sulfur-bound Cadmium in the Cd-hyperaccumulator Solanum nigrum and the non-accumulator Solanum melongena
2021
Pons, Marie-Noëlle | Collin, Blanche | Doelsch, Emmanuel | Chaurand, Perrine | Fehlauer, Till | Levard, Clément | Keller, Catherine | Rose, Jérôme
It has been proposed that non-protein thiols and organic acids play a major role in cadmium phytoavailability and distribution in plants. In the Cd-hyperaccumulator Solanum nigrum and non-accumulator Solanum melongena, the role of these organic ligands in the accumulation and detoxification mechanisms of Cd are debated. In this study, we used X-ray absorption spectroscopy to investigate Cd speciation in these plants (roots, stem, leaves) and in the soils used for their culture to unravel the plants responses to Cd exposure. The results show that Cd in the 100 mg.kg-1 Cd-doped clayey loam soil is sorbed onto iron oxyhydroxides. In both S. nigrum and S. melongena, Cd in roots and fresh leaves is mainly bound to thiol ligands, with a small contribution of inorganic S ligands in S. nigrum leaves. We interpret the Cd binding to sulfur ligands as detoxification mechanisms, possibly involving the sequestration of Cd complexed with glutathione or phytochelatins in the plant vacuoles. In the stems, results show an increase binding of Cd to -O ligands (>50% for S. nigrum). We suggest that Cd is partly complexed by organic acids for transportation in the sap.
Afficher plus [+] Moins [-]Size-dependent impact of polystyrene microplastics on the toxicity of cadmium through altering neutrophil expression and metabolic regulation in zebrafish larvae
2021
Qin, Li | Duan, Zhenghua | Cheng, Haodong | Wang, Yudi | Zhang, Haihong | Zhu, Zhe | Wang, Lei
Insufficient evidence exists regarding the visible physiological toxic endpoints of MPs exposures on zebrafish larvae due to their small sizes. Herein, the impacts of micro-polystyrene particles (μ-PS) and 100 nm polystyrene particles (n-PS) on the toxicity of cadmium (Cd) through altering neutrophil expressions were identified and quantified in the transgenic zebrafish (Danio rerio) larvae Tg(lyz:DsRed2), and the effects were size-dependent. When exposed together with μ-PS, the amount of neutrophils in Cd treated zebrafish larvae decreased by 25.56% through reducing Cd content in the larvae. By contrast, although n-PS exposure caused lower Cd content in the larvae, the expression of neutrophils under their combined exposure remained high. The mechanism of immune toxicity was analyzed based on the results of metabonomics. n-PS induced high oxidative stress in the larvae, which promoted taurine metabolism and unsaturated fatty biosynthesis in n-PS + Cd treatment. This observation was accordance with the significant inhibition of the activities of superoxide dismutase and catalase enzymes detected in their combined treatment. Moreover, n-PS promoted the metabolic pathways of catabolic processes, amino acid metabolism, purine metabolism, and steroid hormone biosynthesis in Cd treated zebrafish larvae. Nanoplasctis widely coexist with other pollutants in the environment at relatively low concentrations. We conclude that more bio-markers of immune impact should be explored to identify their toxicological mechanisms and mitigate the effects on the environment.
Afficher plus [+] Moins [-]Cadmium exposure induces osteoporosis through cellular senescence, associated with activation of NF-κB pathway and mitochondrial dysfunction
2021
Luo, Huigen | Gu, Renjie | Ouyang, Huiya | Wang, Lihong | Shi, Shanwei | Ji, Yuna | Bao, Baicheng | Liao, Guiqing | Xu, Baoshan
Cadmium (Cd) is a heavy metal toxicant as a common pollutant derived from many agricultural and industrial sources. The absorption of Cd takes place primarily through Cd-contaminated food and water and, to a significant extent, via inhalation of Cd-contaminated air and cigarette smoking. Epidemiological data suggest that occupational or environmental exposure to Cd increases the health risk for osteoporosis and spontaneous fracture such as itai-itai disease. However, the direct effects and underlying mechanism(s) of Cd exposure on bone damage are largely unknown. We used primary bone marrow-derived mesenchymal stromal cells (BMMSCs) and found that Cd significantly induced BMMSC cellular senescence through over-activation of NF-κB signaling pathway. Increased cell senescence was determined by production of senescence-associated secretory phenotype (SASP), cell cycle arrest and upregulation of p21/p53/p16ᴵᴺᴷ⁴ᵃ protein expression. Additionally, Cd impaired osteogenic differentiation and increased adipogenesis of BMMSCs, and significantly induced cellular senescence-associated defects such as mitochondrial dysfunction and DNA damage. Sprague-Dawley (SD) rats were chronically exposed to Cd to verify that Cd significantly increased adipocyte number, and decreased mineralization tissues of bone marrow in vivo. Interestingly, we observed that Cd exposure remarkably retarded bone repair and regeneration after operation of skull defect. Notably, pretreatment of melatonin is able to partially prevent Cd-induced some senescence-associated defects of BMMSCs including mitochondrial dysfunction and DNA damage. Although Cd activated mammalian target of rapamycin (mTOR) pathway, rapamycin only partially ameliorated Cd-induced cell apoptosis rather than cellular senescence phenotypes of BMMSCs. In addition, a selective NF-κB inhibitor moderately alleviated Cd-caused the senescence-related defects of the BMMSCs. The study shed light on the action and mechanism of Cd on osteoporosis and bone ageing, and may provide a novel option to ameliorate the harmful effects of Cd exposure.
Afficher plus [+] Moins [-]A synthesis framework using machine learning and spatial bivariate analysis to identify drivers and hotspots of heavy metal pollution of agricultural soils
2021
Yang, Shiyan | Taylor, David | Yang, Dong | He, Mingjiang | Liu, Xingmei | Xu, Jianming
Source apportionment can be an effective tool in mitigating soil pollution but its efficacy is often limited by a lack of information on the factors that influence the accumulation of pollutants at a site. In response to this limitation and focusing on a suite of heavy metals identified as priorities for pollution control, the study established a comprehensive pollution control framework using factor identification coupled with spatial agglomeration for agricultural soils in an industrialized part of Zhejiang Province, China. In addition to elucidating the key role of industrial and traffic activities on heavy metal accumulation through implementing a receptor model, specific influencing factors were identified using a random forest model. The distance from the soil sample location to the nearest likely industrial source was the most important factor in determining cadmium and copper concentrations, while distance to the nearest road was more important for lead and zinc pollution. Soil parent materials, pH, organic matter, and clay particle size were the key factors influencing accumulation of arsenic, chromium, and nickel. Spatial auto-correlation between levels of soil metal pollution and industrial agglomeration can enable a more targeted approach to pollution control measures. Overall, the approach and results provide a basis for improved accuracy in source apportionment, and thus improved soil pollution control, at the regional scale.
Afficher plus [+] Moins [-]Blood cadmium and physical function limitations in older adults
2021
García-Esquinas, Esther | Téllez-Plaza, María | Pastor-Barriuso, Roberto | Ortolá, Rosario | Olmedo, Pablo | Gil, Fernando | López-García, Esther | Navas-Acien, Ana | Rodríguez-Artalejo, Fernando
Cadmium (Cd) is a toxic metal found in tobacco, air and food. Recent cross-sectional studies have suggested that Cd negatively impacts physical performance, but the prospective association is uncertain.We used data from 2548 older adults from the Seniors-ENRICA II cohort in Madrid, Spain. Whole blood Cd levels were measured at baseline using inductively coupled plasma-mass spectrometry. At baseline (2017) and follow-up (2019), overall physical function was evaluated using the physical component summary (PCS) of the SF 12-Item Health questionnaire, lower-extremity performance with the Short Physical Performance Battery (SPPB), muscle weakness with a hand dynamometer, and frailty with a Deficit Accumulation index. Mobility limitations and disability in instrumental activities of daily living (IADL) were ascertained with standardized questionnaires. Analyses were adjusted for relevant confounders, including tobacco smoke, number of cigarettes smoked per day and time since cessation in former smokers.In cross-sectional analyses, odds ratios (95% confidence interval) per two-fold increase in blood Cd were 1.16 (1.03; 1.31) for low PCS scores, 1.08 (0.97; 1.20) for impaired lower-extremity performance, 1.10 (0.98; 1.23) for low grip strength, 1.11 (1.02; 1.20) for mobility limitations, 1.16 (1.02; 1.31) for frailty, and 1.26 (1.08; 1.47) for IADL disability. In longitudinal analyses, corresponding hazard ratios were 1.25 (1.03; 1.51) for low PCS scores, 1.14 (1.03; 1.27) for impaired lower-extremity performance, 1.02 (0.92; 1.13) for low grip strength, 1.03 (0.91; 1.16) for mobility limitations, and 1.16 (1.00; 1.35) for frailty. All the associations where consistent when current smokers were excluded from the analyses.Our results support the role of Cd as a risk factor for physical function impairments in older adults.
Afficher plus [+] Moins [-]Molecular level study of cadmium adsorption on dithiocarbamate modified chitosan
2021
Yin, Zheng | Qiu, Dong | Zhang, Meiyi
It has been shown that chemical modification of chitosan with sulfur (S) functional groups could significantly enhance its chelating capability with heavy metals included Cd(II). However, a molecular level understanding has been lacking. Here, we carried out X-ray absorption fine structure (XAFS) and Fourier transformed infrared (FTIR) spectra studies to bridge this knowledge gap. The results indicate that both Cd–O/N and Cd–S bonds exist in the complex of Cd(II) with dithiocarbamate chitosan (DTC-CTS). S functional groups (dithiocarbamate) in DTC-CTS play the major role in complexation with Cd(II) and S content affects the adsorption mechanism. At low S content, Cd(II) is mainly adsorbed on DTC-CTS as an outer-sphere complex with two monodentate amino groups and two water molecules in tetrahedral configuration. At high S content, Cd adsorption dominantly occurs by formation of an inner-sphere complex with two bidentate mononuclear S ligands in tetrahedral configuration. This investigation provides information on the effectiveness and mechanisms of Cd(II) removal that is critical for evaluating modified chitosan applications for stabilization of Cd(II) in surface water, groundwater, soils and sediments.
Afficher plus [+] Moins [-]Tracing the fate of phosphorus fertilizer derived cadmium in soil-fertilizer-wheat systems using enriched stable isotope labeling
2021
Bracher, Christoph | Frossard, Emmanuel | Bigalke, Moritz | Imseng, Martin | Mayer, J. (Jochen) | Wiggenhauser, Matthias
Applying mineral phosphorus (P) fertilizers introduces a considerable input of the toxic heavy metal cadmium (Cd) into arable soils. This study investigates the fate of P fertilizer derived Cd (Cddff) in soil-wheat systems using a novel combination of enriched stable Cd isotope mass balances, sequential extractions, and Bayesian isotope mixing models. We applied an enriched ¹¹¹Cd labeled mineral P fertilizer to arable soils from two long-term field trials with distinct soil properties (a strongly acidic pH and a neutral pH) and distinct past mineral P fertilizer application rates. We then cultivated wheat in a pot trial on these two soils. In the neutral soil, Cd concentrations in the soil and the wheat increased with increasing past mineral P fertilizer application rates. This was not the case in the strongly acidic soil. Less than 2.3% of freshly applied Cddff was taken up by the whole wheat plant. Most of the Cddff remained in the soil and was predominantly (>95% of freshly applied Cddff) partitioned into the easily mobilizable acetic acid soluble fraction (F1) and the potentially mobile reducible fraction (F2). Soil pH was the determining factor for the partitioning of Cddff into F1, as revealed through a recovery of about 40% of freshly applied Cddff in F1 in the neutral pH soil compared with about 60% in the strongly acidic soil. Isotope mixing models showed that F1 was the predominant source of Cd for wheat on both soils and that it contributed to over 80% of the Cd that was taken up by wheat. By tracing the fate of Cddff in entire soil-plant systems using different isotope source tracing approaches, we show that the majority of Cddff remains mobilizable and is potentially plant available in the subsequent crop cycle.
Afficher plus [+] Moins [-]Hemin-decreased cadmium uptake in pak choi (Brassica chinensis L.) seedlings is heme oxygenase-1 dependent and relies on its by-products ferrous iron and carbon monoxide
2021
Su, Nana | Niu, Mengyang | Liu, Ze | Wang, Lu | Zhu, Zhengbo | Zou, Jianwen | Chen, Yahua | Cui, Jin
Cadmium (Cd) is a major pollutant in farmland, which not only greatly restricts crop production, but also brings a serious threat to human health through entering the food chain. Our previous study showed that hemin treatment could reduce the accumulation of Cd in pak choi seedlings. However, the underlying mechanism remains unclear. In this study, we used non-invasive micro-test technology (NMT) to detect the real-time Cd²⁺ flux from pak choi roots and demonstrated that hemin treatment decreased Cd uptake rather than its translocation within plants. Moreover, through comparing the responses of different chemical treatments in pak choi seedlings and Arabidopsis wild-type and heme oxygenase-1 (HO-1) mutant, we provided evidence that hemin-decreased Cd uptake was HO-1 dependent. Furthermore, analyses of hemin degradation products suggested that the hemin-derived suppression of Cd uptake suppression was probably relying on its degradation by-products, ferrous iron (Fe²⁺) and carbon monoxide (CO), via repressing the expression of a Fe²⁺/Cd²⁺ transporter BcIRT1 in pak choi roots.
Afficher plus [+] Moins [-]Identification of three metallothioneins in the black soldier fly and their functions in Cd accumulation and detoxification
2021
Zhang, Jie | Shi, Zhihui | Gao, Zhenghui | Wen, Yiting | Wang, Wanqiang | Liu, Wen | Wang, Xiaoping | Zhu, Fen
The black soldier fly (BSF) Hermetia illucens has a strong tolerance to cadmium stress. This helps to use BSF in entomoremediation of heavy metal pollution. Rich metallothionein (MT) proteins were thought to be important for some insects to endure the toxicity of heavy metal. We identified and characterized three MTs genes in BSF (BSFMTs), including BSFMT1, BSFMT2A, and BSFMT2B. Molecular modeling was used to predict metal binding sites. Phylogenetic analysis was used to identify gene families. Overexpression of the recombinant black soldier fly metallothioneins was found to confer Cd tolerance in Escherichia coli. Finally, functions of BSFMTs in BSF were explored through RNA interference (RNAi). RNAi results of BSFMT2B showed that the larval fresh weight decreased significantly, and the larvae mortality increased significantly. This study suggests that BSFMTs have important properties in Cd detoxification and tolerance in BSF. Further characterization analyses of physiological function about metallothioneins are necessary in BSF and other insects.
Afficher plus [+] Moins [-]Ammonium-nitrogen addition at the seedling stage does not reduce grain cadmium concentration in two common wheat (Triticum aestivum L.) cultivars
2021
Cheng, Yiran | Yang, Tian | Xiang, Wenhui | Li, Siyu | Fan, Xing | Sha, Lina | Kang, Houyang | Wu, Dandan | Zhang, Haiqin | Zeng, Jian | Zhou, Yonghong | Wang, Yi
High cadmium (Cd) concentration in common wheat (Triticum aestivum L.) grains poses potential health risks. Several management strategies have been used to reduce grain Cd concentration. However, limited information is available on the use of ammonium-nitrogen (NH₄⁺-N) as a strategy to manage Cd concentration in wheat grains. In this study, NH₄⁺-N addition at the seedling stage unchanged the grain Cd concentration in the high-Cd accumulator, Zhoumai 18 (ZM18), but dramatically increased that in the low-Cd accumulator, Yunmai 51 (YM51). Further analysis revealed that the effects of NH₄⁺-N addition on whole-plant Cd absorption, root-to-shoot Cd translocation, and shoot-to-grain Cd remobilization were different between the two wheat cultivars. In ZM18, NH₄⁺-N addition did not change whole-plant Cd absorption, but inhibited root-to-shoot Cd translocation and Cd remobilization from lower internodes, lower leaves, node 1, and internode 1 to grains via the down-regulation of yellow stripe-like transporters (YSL), zinc transporters (ZIP5, ZIP7, and ZIP10), and heavy-metal transporting ATPases (HMA2). This inhibition decreased the grain Cd content by 29.62%, which was consistent with the decrease of the grain dry weight by 23.26%, leading to unchanged grain Cd concentration in ZM18. However, in YM51, NH₄⁺-N addition promoted continuous Cd absorption during grain filling, root-to-shoot Cd translocation and whole-plant Cd absorption. The absorbed Cd was directly transported to internode 1 via the xylem and then re-transported to grains via the phloem by up-regulated YSL, ZIP5, and copper transporters (COPT4). This promotion increased the grain Cd content by 245.35%, which was higher than the increased grain dry weight by 132.89%, leading to increased grain Cd concentration in YM51. Our findings concluded that the addition of NH₄⁺-N fertilizer at the seedling stage is not suitable for reducing grain Cd concentration in common wheat cultivars.
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