Cadmium (Cd) is highly toxic to most organisms, but some rare plant species can hyperaccumulate Cd in aboveground tissues without suffering from toxicity. The mechanism underlying Cd detoxification ...by hyperaccumulators is interesting but unclear.
Here, the heavy metal ATPase 3 (SpHMA3) gene responsible for Cd detoxification was isolated from the Cd/zinc (Zn) hyperaccumulator Sedum plumbizincicola. RNA interference (RNAi)-mediated silencing and overexpression of SpHMA3 were induced to investigate its physiological functions in S. plumbizincicola and a nonhyperaccumulating ecotype of Sedum alfredii.
Heterologous expression of SpHMA3 in Saccharomyces cerevisiae showed Cd-specific transport activity. SpHMA3 was highly expressed in the shoots and the protein was localized to the tonoplast. The SpHMA3-RNAi lines were hypersensitive to Cd but not to Zn, with the growth of shoots and young leaves being severely inhibited by Cd. Overexpressing SpHMA3 in the nonhyperaccumulating ecotype of S. alfredii greatly increased its tolerance to and accumulation of Cd, but not Zn.
These results indicate that elevated expression of the tonoplast-localized SpHMA3 in the shoots plays an essential role in Cd detoxification, which contributes to the maintenance of the normal growth of young leaves of S. plumbizincicola in Cd-contaminated soils.
Arsenic (As) pollution is a global problem, and the plant-based cleanup of contaminated soils, called phytoremediation, is therefore of great interest. Recently, transgenic approaches have been ...designed to develop As phytoremediation technologies. Here, we used a one-gene transgenic approach for As tolerance and accumulation in Arabidopsis thaliana . PvACR3, a key arsenite As(III) antiporter in the As hyperaccumulator fern Pteris vittata , was expressed in Arabidopsis , driven by the CaMV 35S promoter. In response to As treatment, PvACR3 transgenic plants showed greatly enhanced tolerance. PvACR3 transgenic seeds could even germinate and grow in the presence of 80 μM As(III) or 1200 μM arsenate As(V) treatments that were lethal to wild-type seeds. PvACR3 localizes to the plasma membrane in Arabidopsis and increases arsenite efflux into external medium in short-term experiments. Arsenic determination showed that PvACR3 substantially reduced As concentrations in roots and simultaneously increased shoot As under 150 μM As(V). When cultivated in As(V)-containing soil (10 ppm As), transgenic plants accumulated approximately 7.5-fold more As in above-ground tissues than wild-type plants. This study provides important insights into the behavior of PvACR3 and the physiology of As metabolism in plants. Our work also provides a simple and practical PvACR3 transgenic approach for engineering As-tolerant and -hyperaccumulating plants for phytoremediation.
The goal of this study was to develop transgenic plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by simultaneous overexpression of
AsPCS1 and
GSH1 ...(derived from garlic and baker’s yeast) in
Arabidopsis thaliana. Phytochelatins (PCs) and glutathione (GSH) are the main binding peptides involved in chelating heavy metal ions in plants and other living organisms. Single-gene transgenic lines had higher tolerance to and accumulated more Cd and As than wild-type. Compared to single-gene transgenic lines, dual-gene transformants exhibited significantly higher tolerance to and accumulated more Cd and As. One of the dual-gene transgenic lines, PG1, accumulated twice the amount of Cd as single-gene transgenic lines. Simultaneous overexpression of
AsPCS1 and
GSH1 led to elevated total PC production in transgenic
Arabidopsis. These results indicate that such a stacking of modified genes is capable of increasing Cd and As tolerance and accumulation in transgenic lines, and represents a highly promising new tool for use in phytoremediation efforts.
The cadmium hyperaccumulator
has remarkable abilities for cadmium (Cd) transport, accumulation and detoxification, but the transcriptional regulation mechanisms responsible for its Cd ...hyperaccumulation remain unknown. To address this knowledge gap, we conducted a comparative transcriptome study between
and the non-hyperaccumulating ecotype (NHE) of
with or without Cd treatment. Our results revealed many differentially expressed genes involved in heavy metal transport and detoxification that were abundantly expressed in
. Additionally, we identified a large number of differentially expressed transcription factor genes, highlighting the complexity of transcriptional regulatory networks. We further screened four transcription factor genes that were highly expressed in the roots of
as candidate genes for creating CRISPR/Cas9 knockout mutations. Among these, the
and
mutant lines exhibited decreased Cd accumulation in their aboveground parts, suggesting that these two transcription factors may play a role in the regulation of the Cd hyperaccumulation in
. Although further research will be required to determine the precise targeted genes of these transcription factors, combined transcriptome analysis and CRISPR/Cas9 technology provides unprecedented opportunities for identifying transcription factors related to Cd hyperaccumulation and contributes to the understanding of the transcriptional regulation mechanism of hyperaccumulation in
.
In Arabidopsis, the nodulin 26-like intrinsic protein （NIP） subfamily of aquaporin proteins consists of nine members, five of which （NIP1;1, NIP1;2, NIP5;1, NIP6;1, and NIP7;1） were previously ...identified to be perme- able to arsenite. However, the roles of NIPs in the root-to-shoot translocation of arsenite in plants remain poorly understood. In this study, using reverse genetic strategies, Arabidopsis NIP3;1 was identified to play an important role in both the arsenic uptake and root-to-shoot distribution under arsenite stress condi- tions. The nip3;1 loss-of-function mutants displayed obvious improvements in arsenite tolerance for aboveground growth and accumulated less arsenic in shoots than those of the wild-type plants, whereas the nip3;1 nip1;1 double mutant showed strong arsenite tolerance and improved growth of both roots and shoots under arsenite stress conditions. A promoter-β-glucuronidase analysis revealed that NIP3; 1 was ex- pressed almost exclusively in roots （with the exception of the root tips）, and heterologous expression in the yeast Saccharomyces cerevisiae demonstrated that NIP3;1 was able to mediate arsenite transport. Taken together, our results suggest that NIP3;1 is involved in arsenite uptake and root-to-shoot translocation in Arabidopsis, probably as a passive and bidirectional arsenite transporter.
► Simultaneous transformation of
AsPCS1 and
ScYCF1 into
Arabidopsis thaliana which is sensitive to heavy metals, leads to transgenic plants tolerant to Arsenic and cadmium. ► Dual-gene transgenic ...Arabidopsis showed higher accumulation of Arsenic and cadmium than single and non-transgenic plants. ► Our results proved that improved thiol peptides synthesis and vacuolar compartmentation in plant dramatically boosted the survival rates of plants when exposed to heavy metals. ► A new strategy for efficient phytoremediation of heavy metals by stacking genes transformation in plants was developed in this article.
Transgenic
Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of
AsPCS1 and
YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2–10 folds cadmium/arsenite and 2–3 folds arsenate than wild type or plants expressing
AsPCS1 or
YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.
The tomb of Hanxiu, a prime minister of the Tang dynasty who died in 740 CE, was decorated with elaborate mural paintings. The pigments used in the mural paintings were collected from representative ...colours before a restoration process and analyzed using micro-Raman and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) analysis to characterize the chemical compositions. The results reveal the chromatic palette and the painting technique used in the mural paintings. Most of the pigments are natural mineral pigments similar to those excavated in previous archaeological works, except the yellow pigment is unusual. A rare mineral pigment, vanadinite Pb5(VO4)3Cl, was employed in a large amount as the yellow pigment. This phenomenon was analyzed and compared with tomb mural paintings from varied periods and locations in ancient China. Notably, the identification of vanadinite via Raman spectra has to be performed carefully and combined with an elemental analysis to avoid misidentification.
Nitric oxide (NO) is a bioactive gas and functions as a signaling molecule in plants exposed to diverse biotic and abiotic stresses including cadmium (Cd²⁺). Cd²⁺ is a non-essential and toxic heavy ...metal, which has been reported to induce programmed cell death (PCD) in plants. Here, we investigated the role of NO in Cd²⁺-induced PCD in tobacco BY-2 cells (Nicotiana tabacum L. cv. Bright Yellow 2). In this work, BY-2 cells exposed to 150 μM CdCl₂ underwent PCD with TUNEL-positive nuclei, significant chromatin condensation and the increasing expression of a PCD-related gene Hsr203J. Accompanied with the occurring of PCD, the production of NO increased significantly. The supplement of NO by sodium nitroprusside (SNP) had accelerated the PCD, whereas the NO synthase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME) and NO-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) alleviated this toxicity. To investigate the mechanism by which NO exerted its function, Cd²⁺ concentration was measured subsequently. SNP led more Cd²⁺ content than Cd²⁺ treatment alone. By contrast, the prevention of NO by l-NAME decreased Cd²⁺ accumulation. Using the scanning ion-selective electrode technique, we analyzed the pattern and rate of Cd²⁺ fluxes. This analysis revealed the promotion of Cd²⁺ influxes into cells by application of SNP, while l-NAME and cPTIO reduced the rate of Cd²⁺ uptake or even resulted in net Cd²⁺ efflux. Based on these founding, we concluded that NO played a positive role in CdCl₂-induced PCD by modulating Cd²⁺ uptake and thus promoting Cd²⁺ accumulation in BY-2 cells.
Cadmium (Cd) is very toxic to plant cells and Cd2+ stress induces programmed cell death (PCD) in Nicotiana tabacum L. cv. bright yellow-2 (BY-2) cells. In plants, PCD can be regulated through the ...endoplasmic reticulum (ER) stress–cell death signaling pathway. However, the mechanism of Cd2+-induced PCD remains unclear. In this study, we found that Cd2+ treatment induced ER stress in tobacco BY-2 cells. The expression of two ER stress markers NtBLP4 and NtPDI and an unfolded protein response related transcription factor NtbZIP60 were upregulated with Cd2+ stress. Meanwhile, the PCD triggered by prolonged Cd2+ stress could be relieved by two ER chemical chaperones, 4-phenylbutyric acid and tauroursodeoxycholic acid. These results demonstrate that the ER stress–cell death signaling pathway participates in the mediation of Cd2+-induced PCD. Furthermore, the ER chaperone AtBiP2 protein alleviated Cd2+-induced ER stress and PCD in BY-2 cells based on the fact that heterologous expression of AtBiP2 in tobacco BY-2 cells reduced the expression of NtBLP4 and a PCD-related gene NtHsr203J under Cd2+ stress conditions. In summary, these results suggest that the ER stress–cell death signaling pathway regulates Cd2+-induced PCD in tobacco BY-2 cells, and that the AtBiP2 protein act as a negative regulator in this process.
The asymmetry of information brings difficulty for government to manage public hospitals. Therefore, Jiading District of Shanghai has been establishing DRGs-based inpatient service management system ...(ISMS) to effectively compare the output of different hospitals through DRGs, reward desired hospital performance and enhance inpatient service capacity. However, the impact of the implementation of DRGs-based inpatient service management (ISM) policy in Jiading district is still unknow. We therefore conducted this study to evaluate the impact of DRGs-based ISM policy on the performance of inpatient service since its implementation in Jiading District, Shanghai, China in 2017.
Using an interrupted time series design, we analyzed quarterly data of seven DRGs-based performance measures from the ISMS which covered all five public hospitals in Jiading District from 2013 to 2019. We utilized the segmented linear regression model to assess the change of level and trend of performance indicators before and after ISM policy. Dickey-Fuller test was used to examine the stationary of the data. Durbin-Watson test was performed to check the series autocorrelation of indicators.
Significant changes in the following indicators were observed since the implementation of ISM policy. The case-mix index (CMI) level decreased by 0.103 (P < 0.05), the trend increased by 0.008 (P < 0.05). The total weight level decreased by 3719.05 (P < 0.05), and the trend increased by 250.13 (P < 0.05). The time efficiency index (TEI) level increased by 0.12 (P < 0.05), and the trend decreased by 0.01 (P < 0.05). The cost efficiency index (CEI) level increased by 0.31 (P < 0.05), and the trend decreased by 0.02 (P < 0.05). No significant difference was found in the change of DRGs number, inpatient mortality of low-risk group cases (IMLRG) and inpatient mortality of medium-to-low risk group cases (IMMLRG).
Findings highlight the role of ISM policy in improving the capacity and efficiency of regional inpatient service. Three prerequisites, including a good information system, high-quality EMR data, and a management team, are needed for other countries to implement their own ISM policy to help government manage public hospitals and improve the performance of regional inpatient service.
PDF
