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1.
J Toxicol Sci ; 45(9): 539-548, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32879253

RESUMO

We investigated the mechanism underlying intestinal cadmium (Cd) uptake based on the mediators (metal transporters) of essential elements, such as Fe, Zn, Cu, and Ca, under normal conditions in female rats. These elements interact with Cd uptake from the intestinal tract. Cd concentration at each site of the small intestine (duodenum, jejunum, and ileum) increased as Cd exposure increased. However, Cd concentration was the highest in the duodenum. The gene expression of ZIP14, DMT1, and ATP7A increased with increase in Cd concentration. Further, Cu concentration decreased as Cd concentration increased. In contrast, Fe concentration displayed a decreasing tendency with the increase in Cd concentration. The gene expression levels of ZIP14, DMT1, and ATP7A were positively correlated with Cd concentration. Immunohistochemical staining revealed the positive sites of ZIP14 and DMT1 scattered in the area adjacent to the goblet cells, resorbable epithelial cells, and lamina propria in the duodenum tissue, according to the increase in Cd concentration. Cd is induced to synthesize and bind to metallothionein (MT-I and -II) and accumulate in the intestinal tissues, mainly in the duodenum. Such findings suggest that Cd, a contaminant element, is taken up from the intestinal tract by multiple metal transporters such as Cu, Fe, and Zn, thereby involving in the intestinal Cd absorption.


Assuntos
Cádmio/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Absorção Intestinal/genética , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Animais , Proteínas de Transporte de Cátions/genética , Cobre , ATPases Transportadoras de Cobre/genética , ATPases Transportadoras de Cobre/metabolismo , Duodeno/metabolismo , Feminino , Expressão Gênica , Ferro , Metalotioneína/metabolismo , Ratos , Zinco
2.
Ecotoxicol Environ Saf ; 203: 110961, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888621

RESUMO

Cadmium (Cd), which seriously affects plant growth and crop production, is harmful to humans. Previous studies revealed ryegrass (Lolium multiflorum Lam.) exhibits Cd tolerance, and may be useful as a potential hyperaccumulator because of its wide distribution. In this study, the physiological and transcriptional responses of two ryegrass cultivars [i.e., high (LmHC) and low (LmLC) Cd tolerance] to Cd stress were investigated and compared. The Cd tolerance of LmHC was greater than that of LmLC at various Cd concentrations. The uptake of Evans blue dye revealed that Cd-induced root cell mortality was higher in LmLC than in LmHC after a 12-h Cd treatment. Furthermore, the content and influx rate of Cd in LmLC roots were greater than in LmHC roots under Cd stress conditions. The RNA sequencing and quantitative real-time PCR data indicated that the Cd transport regulatory genes (ABCG37, ABCB4, NRAMP4, and HMA5) were differentially expressed between the LmLC and LmHC roots. This expression-level diversity may contribute to the differences in the Cd accumulation and translocation between LmLC and LmHC. These findings may help clarify the physiological and molecular mechanisms underlying ryegrass responses to Cd toxicity. Additionally, ryegrass may be able to hyperaccumulate toxic heavy metals during the phytoremediation of contaminated soil.


Assuntos
Adaptação Biológica , Cádmio/metabolismo , Lolium/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poluentes do Solo/metabolismo , Transcrição Genética/efeitos dos fármacos , Adaptação Biológica/efeitos dos fármacos , Adaptação Biológica/genética , Biodegradação Ambiental , Cádmio/análise , Cádmio/toxicidade , Genes de Plantas , Lolium/química , Lolium/genética , Raízes de Plantas/química , Raízes de Plantas/genética , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
3.
Ecotoxicol Environ Saf ; 205: 111298, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32950806

RESUMO

Mulberry (Morus atropurpurea) is an economically important woody tree and has great potential for the remediation of heavy metals. To investigate how cadmium accumulates and its detoxification in mulberry, we assessed the physiological and transcriptomic effects of cadmium contamination and as well as its chemical forms and subcellular distribution. Cadmium significantly inhibited mulberry plant growth and primarily accumulated in mulberry roots. Antioxidant enzymes were induced by cadmium in all tissues of mulberry. Subcellular fractionation analyses of cadmium indicated that the majority was compartmentalized in soluble fraction in roots while it mainly located in cell wall in leaves and stems. The greatest amount of the cadmium was integrated with proteins and pectates in all mulberry tissues. RNA-seq transcriptomic analyses of mulberry roots revealed that various metabolic pathways involved in cadmium stress response such as RNA regulation, hormone metabolism, and response to stress, secondary metabolism, as well as signaling, protein metabolism, transport, and cell-wall metabolism. These results will increase our understanding of the molecular mechanisms of cadmium detoxification in mulberry and provide new insights into engineering woody plants for phytoremediation.


Assuntos
Bioacumulação , Cádmio/toxicidade , Morus/efeitos dos fármacos , Poluentes do Solo/toxicidade , Estresse Fisiológico/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , Perfilação da Expressão Gênica , Morus/crescimento & desenvolvimento , Morus/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo , Estresse Fisiológico/genética
4.
Ecotoxicol Environ Saf ; 205: 111333, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979802

RESUMO

Plant growth-promoting rhizobacteria (PGPR) are a specific category of microbes that improve plant growth and promote greater tolerance to metal stress through their interactions with plant roots. We evaluated the effects of phytoremediation combining the cadmium accumulator Solanum nigrum L. and two Cd- and Pb-resistant bacteria isolates. To understand the interaction between PGPR and their host plant, we conducted greenhouse experiments with inoculation treatments at Nanjing Agricultural University (Jiangsu Province, China), in June 2018. Two Cd- and Pb-resistant PGPR with various growth-promoting properties were isolated from heavy metal-contaminated soil. 16S rRNA analyses indicated that the two isolates were Bacillus genus, and they were named QX8 and QX13. Pot experiments demonstrated that inoculation may improve the rhizosphere soil environment and promote absorption of Fe and P by plants. Inoculation with QX8 and QX13 also enhanced the dry weight of shoots (1.36- and 1.7-fold, respectively) and roots (1.42- and 1.96-fold) of plants growing in Cd- and Pb-contaminated soil, and significantly increased total Cd (1.28-1.81 fold) and Pb (1.08-1.55 fold) content in aerial organs, compared to non-inoculated controls. We also detected increases of 23% and 22% in the acid phosphatase activity of rhizosphere soils inoculated with QX8 and QX13, respectively. However, we did not detect significant differences between inoculated and non-inoculated treatments in Cd and Pb concentrations in plants and available Cd and Pb content in rhizosphere soils. We demonstrated that PGPR-assisted phytoremediation is a promising technique for remediating heavy metal-contaminated soils, with the potential to enhance phytoremediation efficiency and improve soil quality.


Assuntos
Cádmio/análise , Chumbo/análise , Rhizobiaceae/metabolismo , Microbiologia do Solo , Poluentes do Solo/análise , Solanum nigrum/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , China , Chumbo/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , RNA Ribossômico 16S , Rizosfera , Solo/química , Poluentes do Solo/metabolismo , Solanum nigrum/crescimento & desenvolvimento , Solanum nigrum/metabolismo
5.
Ecotoxicol Environ Saf ; 202: 110903, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800238

RESUMO

Cadmium (Cd) is a type of toxic metal, in most cases, coming from fuel burning and aquatic plants. The cells of organisms can be caused serious damage, including pyroptosis, exposure to low concentrations of Cd in long-term. Pyroptosis is a recently discovered Caspase-1-mediated cell death. In this study, lymphocytes were extracted from the pronephros and spleens in carps, respectively. After treating cells with low concentration of Cd, the mRNA and protein expression levels of pyroptosis-related genes, NLRP3, Caspase-1, and pro-inflammatory cytokines, increased obviously. And the content of reactive oxygen species (ROS) and mitochondria reactive oxygen species (mtROS) increased significantly, we also found the activities of CAT, GSH-px and T-SOD reduce significantly, and the content of MDA have a clear upward trend. We then added NLRP3 inhibitor, Glyburide, to the Cd-treated group, further confirming that NLRP3 is a key gene in pyroptosis pathways by detecting the mRNA and protein expression levels. Besides, the rupture of the cell membrane was also confirmed by Hoechst/PI double staining, red fluorescence increased obviously in the Cd treatment group. The experiment revealed that Cd exposure induces pyroptosis of lymphocytes in carp pronephros and spleens by activating NLRP3. Inhibition of NLRP3 activity can slow down the degree of lymphocytes pyroptosis. Thus, the above information provides a new avenue toward understanding the partial mechanism of Cd exposure-induced pyroptosis.


Assuntos
Cádmio/toxicidade , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Pronefro/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Cádmio/metabolismo , Carpas/metabolismo , Carpas/fisiologia , Caspase 1 , Inflamassomos/metabolismo , Linfócitos , Mitocôndrias/metabolismo , Piroptose/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Baço/metabolismo
6.
Ecotoxicol Environ Saf ; 202: 110906, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800241

RESUMO

The nonsteroidal anti-inflammatory drug diclofenac (DCF) is considered a contaminant of emerging concern. DCF can co-exist with heavy metals in aquatic environments, causing unexpected risks to aquatic organisms. This study aimed to assess the combined effects of DCF and cadmium (Cd) at environmentally relevant concentrations on the bioconcentration and status of oxidative stress and detoxification in Chironomus riparius larvae. The larvae were exposed to DCF (2 and 20 µg L-1) and Cd (5 and 50 µg L-1) alone or in mixtures for 48 h. The combined exposure to DCF and Cd was found to reciprocally facilitate the accumulation of each compound in larvae compared with single exposures. As indicated by the antioxidant enzyme activities, reduced glutathione levels, and malondialdehyde contents, the low concentration of the mixture (2 µg L-1 DCF + 5 µg L-1 Cd) did not alter the oxidative stress status in larvae, while the high concentration of the mixture (20 µg L-1 DCF + 50 µg L-1 Cd) induced stronger oxidative damage to larvae compared with single exposures. The expression levels of eight genes (CuZnSOD, MnSOD, CAT, GSTd3, GSTe1, GSTs4, CYP4G, and CYP9AT2) significantly decreased due to the high concentration of the mixture compared with single exposures in most cases. Overall, the results suggest that the mixture of DCF and Cd might exert greater ecological risks to aquatic insects compared with their individual compounds.


Assuntos
Cádmio/toxicidade , Chironomidae/fisiologia , Diclofenaco/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Cádmio/metabolismo , Chironomidae/efeitos dos fármacos , Diclofenaco/metabolismo , Inativação Metabólica/efeitos dos fármacos , Larva/efeitos dos fármacos , Malondialdeído/metabolismo , Metais Pesados/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/metabolismo
7.
Ecotoxicol Environ Saf ; 202: 110908, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800243

RESUMO

Chinese milk vetch is an efficient approach to reduce Cd accumulation in rice, nevertheless, its reduction mechanism is not well understood. In this study, we investigated the rice grain Cd, soil properties and microbial community in a Cd-polluted paddy field amended with milk vetch residue (MV) or without (CK) during rice growth period. We found that milk vetch residue averagely decreased the Cd content in rice grain by 45%. Decrease of Cd in rice mainly attributed to the inhibition of Cd activation by milk vetch residue at heading stage probably by the formation of HA-Cd (Humic Acid) and CdS. Increased pH and organic matter (OM) promoted the reduction of available Cd. In addition, nonmetric multidimensional scaling (NMDS) analysis revealed that microbial community structure was significantly different between MV and CK treatment (r = 0.187, p = 0.002), and the core functions of differentially abundant genera were mainly associated with N-cycling, organic matter degradation and sulfate-reducing. The application of milk vetch residue increased the abundance of sulfate-reducing bacteria (SRB) by 8-112% during the rice growth period, which may involve in promoting the transformation of Cd to a more stably residual Cd (CdS). Canonical correspondence analysis (CCA) and mantel test analysis indicated that available K (p = 0.004) and available N (p = 0.005) were the key environmental factors of shaping the SRB. Altogether, changes in soil properties affected microbial structure and functional characteristics, especially the response of SRB in MV treatment would provide valuable insights into reducing the bioavailability of Cd in soil.


Assuntos
Astrágalo (Planta)/metabolismo , Cádmio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Animais , Astrágalo (Planta)/microbiologia , Disponibilidade Biológica , Grão Comestível/química , Substâncias Húmicas/análise , Resíduos Industriais , Microbiota , Leite , Solo/química , Poluentes do Solo/análise
8.
Ecotoxicol Environ Saf ; 202: 110917, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800252

RESUMO

Cadmium (Cd) is an extremely toxic environmental pollutant with high mobility in soils, which can contaminate groundwater, increasing its risk of entering the food chain. Yeast biosorption can be a low-cost and effective method for removing Cd from contaminated aqueous solutions. We transformed wild-type Saccharomyces cerevisiae (WT) with two versions of a Populus trichocarpa gene (PtMT2b) coding for a metallothionein: one with the original sequence (PtMT2b 'C') and the other with a mutated sequence, with an amino acid substitution (C3Y, named here: PtMT2b 'Y'). WT and both transformed yeasts were grown under Cd stress, in agar (0; 10; 20; 50 µM Cd) and liquid medium (0; 10; 20 µM Cd). Yeast growth was assessed visually and by spectrometry OD600. Cd removal from contaminated media and intracellular accumulation were also quantified. PtMT2b 'Y' was also inserted into mutant strains: fet3fet4, zrt1zrt2 and smf1, and grown under Fe-, Zn- and Mn-deficient media, respectively. Yeast strains had similar growth under 0 µM, but differed under 20 µM Cd, the order of tolerance was: WT < PtMT2b 'C' < PtMT2b 'Y', the latter presenting 37% higher growth than the strain with PtMT2b 'C'. It also extracted ~80% of the Cd in solution, and had higher intracellular Cd than WT. Mutant yeasts carrying PtMT2b 'Y' had slightly higher growth in Mn- and Fe-deficient media than their non-transgenic counterparts, suggesting the transgenic protein may chelate these metals. S. cerevisiae carrying the altered poplar gene offers potential for bioremediation of Cd from wastewaters or other contaminated liquids.


Assuntos
Biodegradação Ambiental , Cádmio/metabolismo , Metalotioneína/genética , Proteínas de Plantas/genética , Populus/genética , Saccharomyces cerevisiae/genética , Poluentes do Solo/metabolismo , Cádmio/toxicidade , Metalotioneína/metabolismo , Metais Pesados/análise , Populus/metabolismo , Saccharomyces cerevisiae/metabolismo , Solo
9.
Ecotoxicol Environ Saf ; 202: 110958, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800230

RESUMO

Phytoremediation is an effective way to repair heavy metal contaminated soil and rhizosphere microorganisms play an important role in plant regulation. Nevertheless, little information is known about the variation of microbial metabolic activities and community structure in rhizosphere during phytoremediation. In this study, the rhizosphere soil microbial metabolic activities and community structure of Trifolium repensL. during Cd-contaminated soil phytoremediation, were analyzed by Biolog EcoPlate™ and high-throughput sequencing. The uptake in the roots of Trifolium repensL. grown in 5.68 and 24.23 mg/kg Cd contaminated soil was 33.51 and 84.69 mg/kg respectively, causing the acid-soluble Cd fractions decreased 7.3% and 5.4%. Phytoremediation significantly influenced microbial community and Trifolium repensL. planting significantly increased the rhizosphere microbial population, diversity, the relative abundance of plant growth promoting bacteria (Kaistobacter and Flavisolibacter), and the utilization of difficultly metabolized compounds. The correlation analysis among substrate utilization and microbial communities revealed that the relative abundance increased microorganisms possessed stronger carbon utilization capacity, which was beneficial to regulate the stability of plant-microbial system. Collectively, the results of this study provide fundamental insights into the microbial metabolic activities and community structure during heavy metal contaminated soil phytoremediation, which may aid in the bioregulation of phytoremediation.


Assuntos
Cádmio/toxicidade , Microbiota/efeitos dos fármacos , Rizosfera , Microbiologia do Solo , Poluentes do Solo/toxicidade , Solo/química , Trifolium/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Poluentes do Solo/metabolismo , Trifolium/crescimento & desenvolvimento , Trifolium/metabolismo , Trifolium/microbiologia
10.
Ecotoxicol Environ Saf ; 205: 111146, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32827965

RESUMO

Cadmium (Cd) exposure in environment is associated with development of esophageal cancer. However, the mechanisms of Cd-induced carcinogenesis are still not been fully cleared, and the present study aimed to explore the possible etiological mechanism of Cd-induced esophageal cancer. Human esophageal epithelial cell lines (HET-1A and KYSE450) were treated with CdCl2 at 0.05 mg/l for 12, 24 h, and the then the apoptosis were detected using flow cytometry with annexin-V-FITC/PI staining. Results showed that apoptosis of treatment groups was significantly inhibited, and decreased reactive oxygen species (ROS) production played a key role in the inhibitory effects by upregulating Bcl-2 and downregulating Caspase-3/9. The relief of oxidative stress during Cd exposure was actively promoted by the increased nicotinamide adenine dinucleotide phosphoric acid and glutathione levels. To investigate the causes of enhanced intracellular antioxidant capacity, the activity of pyruvate kinase (PK), a key enzyme of glycolysis, was detected. Our results showed that PK activity was inhibited, suggesting that glycolysis process was blocked which promoted more intermediate metabolites of glycolysis to be used for reduced nicotinamide adenine dinucleotide phosphoric acid (NADPH) or other antioxidants synthesis. PK activity was closely correlated with phosphorylation of pyruvate kinase M2 (PKM2), and a highly negative correlation (correlation coefficients: -0.835, p < 0.05) between them was found. Western blotting showed the overphosphorylation of PKM2 in Cd-exposed cells, resulting from increased expression of cyclin-dependent kinases 6 (CDK6). These results suggested a possible mechanism of carcinogenic: Cd-induced upregulation of CDK6 in esophageal cell lines caused PKM2 overphosphorylation inhibiting PK activity, thereby shunting glucose-derived carbon into the pentose phosphate pathway and promoting the production of NADPH and reduced glutathione (GSH) to neutralize ROS, which finally results in the inhibited apoptosis.


Assuntos
Cádmio/toxicidade , Quinase 6 Dependente de Ciclina/metabolismo , Apoptose/efeitos dos fármacos , Cádmio/metabolismo , Caspase 3 , Neoplasias Esofágicas , Glicólise/efeitos dos fármacos , Humanos , Estresse Oxidativo/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2 , Piruvato Quinase/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Regulação para Cima
11.
Ecotoxicol Environ Saf ; 205: 111144, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846295

RESUMO

Cadmium (Cd) contamination is the most common and extensive heavy metal pollution in the farmland of China. Phytoremediation is considered as a promising measure for Cd-contaminated soil remediation, but the remediation efficiency still needs to be enhanced. Biochar as an effective amendment medium is widely manufactured and studied for the soil remediation of heavy metals. In this study, a greenhouse pot trial was conducted to investigate the effects of cornstalk biochar on Cd accumulation of Beta vulgaris var. cicla L. (Beta vulgaris) in Cd contaminated soil. The Cd availability, speciation and nutrients in soil, biomass and Cd chemical forms in the Beta vulgaris root were studied to explore the mechanism that how the cornstalk biochar promoted Cd accumulation in Beta vulgaris. Biochar amendment reduced the DTPA-extractable Cd concentration and stimulated the growth of root. Compared to the Beta vulgaris without biochar treatment, the results of 5% biochar amendment showed that the root dry weight of Beta vulgaris increased to 267%, Cd accumulation in Beta vulgaris increased to 206% and the Cd concentration in leaves and roots increased by 36% and 52%, respectively. Additionally, after 5% biochar was applied to soil, the total content of organic matter-bound Cd and residual Cd increased by 38%, while the content of Fe-Mn oxides-bound Cd decreased by 40%. Meanwhile, Cd may mainly bind to the root cell wall and the ratio of NaCl-extracted Cd to HAc-extracted Cd increased to 166% with 5% biochar amendment. According to our study, Cd in soil can be removed by Beta vulgaris and phytoremediation efficiency can be improved with biochar amendment. The combination of phytoremediation and biochar amendment is a promising strategy for the Cd-contaminated soil remediation.


Assuntos
Beta vulgaris/metabolismo , Biodegradação Ambiental , Cádmio/metabolismo , Poluentes do Solo/metabolismo , Biomassa , Carvão Vegetal , China , Metais Pesados/análise , Solo/química , Poluentes do Solo/análise
12.
Ecotoxicol Environ Saf ; 205: 111145, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846296

RESUMO

This study characterizes sunflower response to the levels of Cd encountered in moderately Cd-polluted soils. Two sunflower cultivars differing in their ability to sequestrate Cd in roots were exposed to low concentrations of Cd (0.5 nM or 100 nM) in hydroponics and sampled after 18 days (258 degree-days) when ten leaves were fully expanded. Plant growth, Cd uptake and partitioning among organs were monitored along with the ionomic (ICP-MS) and the metabolic (1H-NMR) composition of the xylem sap. Sunflower tolerance to Cd differed between the two cultivars. The cultivar with the highest ability to sequestrate Cd in roots (Kapllan) was more tolerant to Cd than the one with the lowest ability (ES RICA). The 23% penalization of plant growth observed at 100 nM in cultivar ES RICA was associated with reduced xylem loading fluxes of soluble sugars, perhaps pointing to disruption of carbohydrate metabolism. Retention of Cd in the stem was higher at 100 nM than at 0.5 nM in the Cd-sensitive cultivar ES RICA, which can be seen as a sunflower strategy to restrict the amount of Cd delivered to the leaves under Cd stress. No direct connection was found between the speciation of Cd in the xylem sap and the Cd translocation efficiency, although significant changes in the free ionic fraction of Cd were observed between the two cultivars at 0.5 nM. The relevance of these results in promoting the use of sunflower in phytomanagement of Cd-polluted soils is discussed.


Assuntos
Cádmio/metabolismo , Helianthus/metabolismo , Hidroponia , Transporte Biológico , Desenvolvimento Vegetal , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Xilema/metabolismo
13.
Ecotoxicol Environ Saf ; 204: 111086, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32781345

RESUMO

In the present research, Silene vulgaris as a representative species growing on both unpolluted and heavy metal (HM) polluted terrains were used to identify ecotype-specific responses to metallic stress. Growth, cell ultrastructure and element accumulations were compared between non-metallicolous (NM), calamine (CAL) and serpentine (SER) specimens untreated with HMs and treated with Pb, Cd and Zn ions under in vitro conditions. Moreover, proteins' modifications related to their level, carbonylation and degradations via vacuolar proteases were verified and linked with potential mechanisms to cope with ions toxicity. Our experiment revealed diversified strategy of HM uptake in NM and both metallicolous ecotypes, in which antagonistic relationship of Zn and Pb/Cd ions provided survival benefits for the whole organism. Despite this similarity, growth rate and metabolic pathways induced in CAL and SER shoots varied significantly. Exposition to HMs in CAL culture led to drop in protein level by approximately 16% compared to the control. This parameter nearly correlated with the enhanced activity of proteases at pH 5.2 as well as possible glutamate changes to proline and reduced glutathione, resulting in intensified growth and first signs of cell senescence. In turn, SER shoots were characterized by growth retardation (to 53% of the control), although protein level and carbonylation were not modified, while a deeper insight into protein network showed its remodeling towards production of polyamines and 2-oxoglutarate delivered to the Krebs cycle. Contrary, an uncontrolled HM influx in NM shoots contributed to morpho-structural disorders accompanied by an increase activity of proteases involved in the degradation of oxidized proteins, what pointed to metal-induced autophagy. Taken together, S. vulgaris ecotypes respond to stress by triggering various mechanisms engaged their survival and/or death under HM treatment.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Proteínas de Plantas/metabolismo , Silene/efeitos dos fármacos , Poluentes do Solo/toxicidade , Zinco/toxicidade , Autofagia/efeitos dos fármacos , Bioacumulação/efeitos dos fármacos , Cádmio/metabolismo , Ecótipo , Glutationa/metabolismo , Chumbo/metabolismo , Modelos Teóricos , Estresse Oxidativo/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Brotos de Planta/ultraestrutura , Silene/crescimento & desenvolvimento , Silene/metabolismo , Silene/ultraestrutura , Poluentes do Solo/metabolismo , Zinco/metabolismo
14.
Ecotoxicol Environ Saf ; 204: 111098, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32798749

RESUMO

Cadmium (Cd) is a detrimental element that can be toxic to plants. The physiological and biochemical responses of plants to Cd stress have been extensively studied, but the molecular mechanisms remain unclear. The present study showed that Cd severely inhibited the growth of roots and shoots and reduced plant biomass of mung bean seedlings. To further investigate the gene profiles and molecular processes in response Cd stress, transcriptome analyses of mung bean roots exposed to 100 µM Cd for 1, 5, and 9 days were performed. Cd treatment significantly decreased global gene expression levels at 5 and 9 d compared with the control. A total of 6737, 10279, and 9672 differentially expressed genes (DEGs) were identified in the 1-, 5-, and 9-day Cd-treated root tissues compared with the controls, respectively. Based on the analysis of DEG function annotation and enrichment, a pattern of mung bean roots response to Cd stress was proposed. The processes detoxification and antioxidative defense were involved in the early response of mung bean roots to Cd. Cd stress downregulated the expressions of a series of genes involved in cell wall biosynthesis, cell division, DNA replication and repair, and photosynthesis, while genes involved in signal transduction and regulation, transporters, secondary metabolisms, defense systems, and mitochondrial processes were upregulated in response to Cd, which might be contributed to the improvement of plant tolerance. Our results provide some novel insights into the molecular processes for growth and adaption of mung bean roots in response to Cd and many candidate genes for further biotechnological manipulations to improve plant tolerance to heavy metals.


Assuntos
Cádmio/toxicidade , Poluentes do Solo/toxicidade , Aclimatação , Adaptação Fisiológica , Antioxidantes/metabolismo , Cádmio/metabolismo , Poluição Ambiental , Fabaceae/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Metais Pesados/metabolismo , Raízes de Plantas/metabolismo , Plântula/metabolismo , Poluentes do Solo/metabolismo , Transcriptoma , Vigna/metabolismo
15.
Ecotoxicol Environ Saf ; 204: 111148, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32818843

RESUMO

To disclose how phosphorus deficiency influence phytoremediation of Cd contamination using poplars, root architecture, Cd absorption, Cd translocation and antioxidant defense in poplar roots were investigated using a clone of Populus × euramericana. Root growth was unaltered by Cd exposure regardless of P conditions, while the degree of root proliferation upon P deficiency was changed by high level of Cd exposure. The concentration and content of Cd accumulation in roots were increased by P deficiency. This can be partially explained by the increased expression of genes encoding PM H + -ATPase under the combined conditions of P deficiency and high Cd exposure, which enhanced Cd2+-H+ exchanges and led to an increment of Cd uptake under P deficiency. Despite of the increasing Cd accumulation in roots, the translocation of Cd from roots to aerial tissues sharply decreased upon P deficiency. The relative expression of genes responsible for Cd translocation (HMA4) decreased upon P deficiency and thus inhibited Cd translocation via xylem. GR activity was decreased by P deficiency, which can inhibit the form of GSH and GSH-Cd complexes and decrease Cd translocation via GSH-Cd complexes. The transportation of PC-Cd complexes into vacuole decreased under P deficiency as a result of the low expression of PCS and ABCC1, and thus suppressed Cd tolerance and Cd detoxification in roots. Moreover, P deficiency decreased the levels of antioxidase (GR and CAT) and phytohormones including JA, ABA and GA3, which synchronously reduced antioxidant capacity in roots.


Assuntos
Cádmio/metabolismo , Fósforo/metabolismo , Populus/fisiologia , Adaptação Fisiológica , Antioxidantes/metabolismo , Biodegradação Ambiental , Transporte Biológico , Cádmio/toxicidade , Proliferação de Células , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/metabolismo , Populus/metabolismo , Xilema/metabolismo
16.
Ecotoxicol Environ Saf ; 204: 111038, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739674

RESUMO

Soil management using fertilizers can modify soil chemical, biochemical and biological properties, including the concentration of trace-elements as cadmium (Cd), chromium (Cd) and nickel (Ni). Bacterial isolates from Cd, Cr, and Ni-contaminated soil were evaluated for some characteristics for their use in bioremediation. Isolates (592) were obtained from soil samples (19) of three areas used in three maize cultivation systems: no-tillage and conventional tillage with the application of mineral fertilizers; minimum tillage with the application of sewage sludge. Four isolates were resistant to Cr3+ (3.06 mmol dm-3) and Cd2+ (2.92 mmol dm-3). One isolate was resistant to the three metals at 0.95 mmol dm-3. All isolates developed in a medium of Cd2+, Cr3+ and Ni2+ at 0.5 mmol dm-3, and removed Cd2+ (17-33%) and Cr6+ (60-70%). They were identified by sequencing of the gene 16S rRNA, as bacteria of the genera Paenibacillus, Burkholderia, Ensifer, and two Cupriavidus. One of the Cupriavidus isolate was able to remove 60% of Cr6+ from the culture medium and showed high indole acetic acid production capacity. We evaluated it in a microbe-plant system that could potentially be deployed in bioremediation by removing toxic metals from contaminated soil.


Assuntos
Bactérias/metabolismo , Cádmio/metabolismo , Cromo/metabolismo , Níquel/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Agricultura , Bactérias/isolamento & purificação , Biodegradação Ambiental , Brasil , Clima Tropical
17.
Ecotoxicol Environ Saf ; 202: 110856, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32629202

RESUMO

To explore the mechanisms underlying the action of the heavy metals Cd and Zn on the photosynthetic function of plant leaves, the effects of 100 µmol L-1 Cd and 200 µmol L-1 Zn stress (the exposure concentrations of Cd and Zn in the culture medium were 2.24 mg kg-1 and 5.36 mg kg-1) on the chlorophyll and carotenoid contents as well as the photosynthetic function of tobacco leaves (Long Jiang 911) were studied. The key proteins in these physiological processes were quantitatively analyzed using a TMT-based proteomics approach. Cd stress was found to inhibit the expression of key enzymes during chlorophyll synthesis in leaves, resulting in a decrease of the Chl content. However, Zn stress did not significantly influence the chlorophyll content. Leaves adapted to Zn stress by upregulating CAO expression and increase the Chl b content. Although the Car content in leaves did not significantly change under either Cd or Zn stress, the expressions of ZE and VDE during Car metabolism decreased significantly under Cd stress. This was accompanied by damages to the xanthophyll cycle and the NPQ-dependent energy dissipation mechanism. In contrast, under Zn stress, leaves adapted to Zn stress by increasing the expression of VDE, thus improving NPQ. Under Cd stress, the expressions of three sets of proteins were significantly down-regulated, including PSII donor-side proteins (PPD3, PPD6, OEE1, OEE2-1, OEE2-2, OEE2-3, and OEE3-2), receptor-side proteins (D1, D2, CP43, CP47, Cyt b559α, Cyt b559ß, PsbL, PsbQ, PsbR, Psb27-H1, and Psb28), and core proteins of the PSI reaction center (psaA, psaB, psaC, psaD, psaE-A, PsaE-B, psaF, psaG, psaH-1, psaK, psaL, psaN, and psaOL). In comparison, only eight of the above proteins (PPD6, OEE3-2, PsbL, PsbQ, Psb27-H1, psaL, and psaOL) were significantly down-regulated by Zn stress. Under Cd stress, both the donor side and the receptor side of PSII were damaged, and PSII and PSI experienced severe photoinhibition. However, Zn stress did not decrease either PSII or PSI activities in tobacco leaves. In addition, the expression of electron transport-related proteins (cytb6/f complex, PC, Fd, and FNR), ATPase subunits, Rubisco subunits, and RCA decreased significantly in leaves under Cd stress. However, no significant changes were observed in any of these proteins under Zn stress. Although Cd stress was found to up-regulate the expressions of PGRL1A and PGRL1B and induce an increase of PGR5/PGRL1-CEF in tobacco leaves, NDH-CEF was significantly inhibited. Under Zn stress, the expressions of ndhH and PGRL1A in leaves were significantly up-regulated, but there were no significant changes in either NDH-CEF or PGR5/PGRL-CEF. Under Cd stress, the expressions of proteins related to Fd-dependent nitrogen metabolism and reactive oxygen species (ROS) scavenging processes (e.g., FTR, Fd-NiR, and Fd-GOGAT) were significantly down-regulated in leaves. However, no significant changes of any of the above proteins were identified under Zn stress. In summary, Cd stress could inhibit the synthesis of chlorophyll in tobacco leaves, significantly down-regulate the expressions of photosynthesis-related proteins or subunits, and suppress both the xanthophyll cycle and NDH-CEF process. The expressions of proteins related to the Fd-dependent nitrogen metabolism and ROS scavenging were also significantly down-regulated, which blocked the photosynthetic electron transport, thus resulting in severe photoinhibition of both PSII and PSI. However, Zn stress had little effect on the photosynthetic function of tobacco leaves.


Assuntos
Cádmio/toxicidade , Carotenoides/metabolismo , Clorofila/metabolismo , Fotossíntese/efeitos dos fármacos , Tabaco/efeitos dos fármacos , Zinco/toxicidade , Cádmio/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Proteômica , Tabaco/metabolismo , Tabaco/fisiologia , Zinco/metabolismo
18.
Huan Jing Ke Xue ; 41(2): 962-969, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608758

RESUMO

Cadmium (Cd) is a highly toxic heavy metal. Brassica rapa (pak choi) is a vastly common vegetable, which readily accumulates Cd. Given the current conditions of Cd contamination in domestic soil, it is important to reduce Cd accumulation in the edible part of pak choi. Research has shown that selenium (Se) can regulate Cd uptake by plants. Cd accumulation (three cultivars) and Cd uptake kinetics in pak choi were investigated under hydroponic conditions. Results showed that the three levels of selenite significantly reduced Cd content in the Hangzhouyoudonger shoot by 50%, while the levels in Suzhouqinggen and Shanghaiqing shoots were not significantly decreased with elevated levels of selenite. Selenite reduces the Cd translocation factors, and higher levels had more obvious effects; 50 µmol·L-1 of selenite significantly decreased the factors by 50% in Hangzhouyoudonger and Suzhouqinggen shoots. Selenite also increased iron (Fe) and manganese (Mn) contents in pak choi, especially in the Hangzhouyoudonger shoot, where 50 µmol·L-1 increased the Fe content by approximately 50%. In the uptake kinetics of Cd, both selenite and selenate significantly increased Cd uptake rates and Vmax by over 100%. Therefore, Se could reduce Cd accumulation in pak choi. This also depended on the tested cultivar. Therefore, reduction effects of Se on the Cd content mainly stemmed from the alteration of Cd translocation in pak choi instead of the uptake competition between Cd and Se.


Assuntos
Brassica rapa/metabolismo , Cádmio/metabolismo , Brotos de Planta/metabolismo , Selênio/metabolismo , Poluentes do Solo/metabolismo , Ácido Selênico , Ácido Selenioso
19.
Huan Jing Ke Xue ; 41(2): 970-978, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608759

RESUMO

A hydroponic experiment was conducted to explore the differences in growth status and Cd accumulation characteristics of two Brassica napus L. cultivars (QY-1 and SYH) under different concentrations of cadmium (Cd) stress (0, 2, and 5 mg·L-1). The Cd subcellular compartmentalization and antioxidant enzyme activities were determined to elucidate the intrinsic mechanism of the differences in the Cd accumulation capacity between the two cultivars of Brassica napus L. Furthermore, field trials were conducted to further verify the differences in phytoremediation of the two cultivars. Results show that neither of the cultivars exhibited obvious growth inhibition under Cd stress. Under the 2 mg·L-1 Cd condition, there were no significant differences in shoot Cd concentrations between the two cultivars. Under 5 mg·L-1 Cd condition, however, the Cd concentrations in both shoot and root of SYH were significantly higher than that of QY-1, which increased by 32.05% and 99.57%, respectively. In addition, the bioconcentration factor (BCF) of the root in SYH is significantly higher than that of QY-1. The subcellular Cd distribution in leaves of the two cultivars of Brassica napus L. showed that, with an increase of Cd stress, Cd concentrations of heat stable protein (HSP) and metal-rich granule (MRG) fractions in leaves significantly increased by 143.69% and 118.91% for QY-1, and by 63.34% and 118.91% for SYH. Thus, the segregation of Cd in HSP and MRG, which was reported to be biological detoxified metal fractions (BDM), might play an important role in the detoxification of Brassica napus L. at a subcellular level under Cd stress. Moreover, the distribution of Cd in the cellular debris fraction might be another important factor contributing to the differences in Cd accumulation of the two Brassica napus L. cultivars, which was 4.41 times higher in SYH than in QY-1 under Cd stress. The results of the antioxidant enzyme activities of two Brassica napus L. cultivars showed that, under the 5 mg·L-1 Cd condition, the antioxidant enzyme system may represent an important detoxification mechanism for QY-1 to cope with stress induced by high concentrations of Cd, while SYH is more effective in reducing the toxicity of Cd by separation of Cd into BDM fractions. The results of the field trial confirmed that the Cd concentrations in the above- and underground parts of SYH were 2.34 and 1.43 times higher than in QY-1, respectively. Therefore, SYH possess a higher Cd phytoextraction capacity than QY-1, and might be a good candidate for the remediation of moderate and mildly Cd-contaminated farmland.


Assuntos
Brassica napus/metabolismo , Cádmio/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Raízes de Plantas , Brotos de Planta
20.
Huan Jing Ke Xue ; 41(2): 979-985, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608760

RESUMO

Chelating agents can increase the bioavailability of heavy metals and enhance their enrichment in plants. The effects of different concentrations of biodegradable chelating agent L-glutamic acid N, N-diacetic acid (GLDA) on the remediation of heavy metal-contaminated soil by super-enriched plant Trifolium repens were investigated by pot experiments with Cd-contaminated soil. Results show that low-dose GLDA could significantly promote the growth of Trifolium repens, and the biomass of Trifolium repens was the highest at 2.5 mmol·kg-1-GLDA, which was 1.30 times that of the control group. Different concentrations of GLDA can increase Cd content of various parts of Trifolium repens. In general, the treatment effect of 5 mmol·kg-1 GLDA was ideal. In this scenario, the root, aerial parts, and whole Cd content were 3.57, 4.69, and 4.67 times of the control group, respectively. GLDA can significantly increase the available Cd content in soil, promote direct absorption at the Trifolium repens roots, and provide better transport to the aerial parts. The prediction model obtained by fitting the linear relationship between physical and chemical properties of soil indicates that GLDA and Trifolium repens Cd content can provide references for the future research of soil-Trifolium repens enrichment. Studies have shown that the biodegradable chelating agent GLDA has potential applications for enhancing phytoremediation of heavy metal Cd contaminated soil.


Assuntos
Cádmio/metabolismo , Glutamatos , Glicina/análogos & derivados , Poluentes do Solo/metabolismo , Trifolium/metabolismo , Biodegradação Ambiental , Ácido Glutâmico , Metais Pesados
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