Rice is a major dietary source of the toxic metalloid arsenic. Reducing arsenic accumulation in rice grain is important for food safety.
We generated transgenic rice overexpressing two aquaporin ...genes, OsNIP1;1 and OsNIP3;3, under the control of a maize ubiquitin promoter or the rice OsLsi1 promoter, and tested the effect on arsenite uptake and translocation.
OsNIP1;1 and OsNIP3;3 were highly permeable to arsenite in Xenopus oocyte assays. Both transporters were localized at the plasma membrane. Knockout of either gene had little effect on arsenite uptake or translocation. Overexpression of OsNIP1;1 or OsNIP3;3 in rice did not affect arsenite uptake but decreased root-to-shoot translocation of arsenite and shoot arsenic concentration markedly. The overexpressed OsNIP1;1 and OsNIP3;3 proteins were localized in all root cells without polarity. Expression of OsNIP1;1 driven by the OsLsi1 promoter produced similar effects. When grown in two arsenic-contaminated paddy soils, overexpressing lines contained significantly lower arsenic concentration in rice grain than the wild-type without compromising plant growth or the accumulation of essential nutrients.
Overexpression of OsNIP1;1 or OsNIP3;3 provides a route for arsenite to leak out of the stele, thus restricting arsenite loading into the xylem. This strategy is effective in reducing arsenic accumulation in rice grain.
Rice grains typically contain high levels of toxic arsenic but low levels of the essential micronutrient selenium. Anthropogenic arsenic contamination of paddy soils exacerbates arsenic toxicity in ...rice crops resulting in substantial yield losses. Here, we report the identification of the gain-of-function arsenite tolerant 1 (astol1) mutant of rice that benefits from enhanced sulfur and selenium assimilation, arsenic tolerance, and decreased arsenic accumulation in grains. The astol1 mutation promotes the physical interaction of the chloroplast-localized O-acetylserine (thiol) lyase protein with its interaction partner serine-acetyltransferase in the cysteine synthase complex. Activation of the serine-acetyltransferase in this complex promotes the uptake of sulfate and selenium and enhances the production of cysteine, glutathione, and phytochelatins, resulting in increased tolerance and decreased translocation of arsenic to grains. Our findings uncover the pivotal sensing-function of the cysteine synthase complex in plastids for optimizing stress resilience and grain quality by regulating a fundamental macronutrient assimilation pathway.
We aimed to evaluate the value of deep learning on positron emission tomography with computed tomography (PET/CT)-based radiomics for individual induction chemotherapy (IC) in advanced nasopharyngeal ...carcinoma (NPC).
We constructed radiomics signatures and nomogram for predicting disease-free survival (DFS) based on the extracted features from PET and CT images in a training set (
= 470), and then validated it on a test set (
= 237). Harrell's concordance indices (C-index) and time-independent receiver operating characteristic (ROC) analysis were applied to evaluate the discriminatory ability of radiomics nomogram, and compare radiomics signatures with plasma Epstein-Barr virus (EBV) DNA.
A total of 18 features were selected to construct CT-based and PET-based signatures, which were significantly associated with DFS (
< 0.001). Using these signatures, we proposed a radiomics nomogram with a C-index of 0.754 95% confidence interval (95% CI), 0.709-0.800 in the training set and 0.722 (95% CI, 0.652-0.792) in the test set. Consequently, 206 (29.1%) patients were stratified as high-risk group and the other 501 (70.9%) as low-risk group by the radiomics nomogram, and the corresponding 5-year DFS rates were 50.1% and 87.6%, respectively (
< 0.0001). High-risk patients could benefit from IC while the low-risk could not. Moreover, radiomics nomogram performed significantly better than the EBV DNA-based model (C-index: 0.754 vs. 0.675 in the training set and 0.722 vs. 0.671 in the test set) in risk stratification and guiding IC.
Deep learning PET/CT-based radiomics could serve as a reliable and powerful tool for prognosis prediction and may act as a potential indicator for individual IC in advanced NPC.
Soil contamination with trace metals and metalloids can cause toxicity to plants and threaten food safety and human health. Plants have evolved sophisticated mechanisms to cope with excess trace ...metals and metalloids in soils, including chelation and vacuolar sequestration. Sulfur-containing compounds, such as glutathione and phytochelatins, play a crucial role in their detoxification, and sulfur uptake and assimilation are regulated in response to the stress of toxic trace metals and metalloids. This review focuses on the multi-level connections between sulfur homeostasis in plants and responses to such stresses, especially those imposed by arsenic and cadmium. We consider recent progress in understanding the regulation of biosynthesis of glutathione and phytochelatins and of the sensing mechanism of sulfur homeostasis for tolerance of trace metals and metalloids in plants. We also discuss the roles of glutathione and phytochelatins in controlling the accumulation and distribution of arsenic and cadmium in plants, and possible strategies for manipulating sulfur metabolism to limit their accumulation in food crops.
Summary
Arsenic can be biomethylated to form a variety of organic arsenicals differing in toxicity and environmental mobility. Trivalent methylarsenite (MAs(III)) produced in the methylation process ...is more toxic than inorganic arsenite (As(III)). MAs(III) also serves as a primitive antibiotic and, consequently, some environmental microorganisms have evolved mechanisms to detoxify MAs(III). However, the mechanisms of MAs(III) detoxification are not well understood. In this study, we identified an arsenic resistance (ars) operon consisting of three genes, arsRVK, that contribute to MAs(III) resistance in Ensifer adhaerens ST2. ArsV is annotated as an NADPH‐dependent flavin monooxygenase with unknown function. Expression of arsV in the arsenic hypersensitive Escherichia coli strain AW3110Δars conferred resistance to MAs(III) and the ability to oxidize MAs(III) to MAs(V). In the presence of NADPH and either FAD or FMN, purified ArsV protein was able to oxidize both MAs(III) to MAs(V) and Sb(III) to Sb(V). Genes with arsV‐like sequences are widely present in soils and environmental bacteria. Metagenomic analysis of five paddy soils showed the abundance of arsV‐like sequences of 0.12–0.25 ppm. These results demonstrate that ArsV is a novel enzyme for the detoxification of MAs(III) and Sb(III) and the genes encoding ArsV are widely present in soil bacteria.
Rice (Oryza sativa) is an important dietary source of both essential micronutrients and toxic trace elements for humans. The genetic basis underlying the variations in the mineral composition, the ...ionome, in rice remains largely unknown. Here, we describe a comprehensive study of the genetic architecture of the variation in the rice ionome performed using genome-wide association studies (GWAS) of the concentrations of 17 mineral elements in rice grain from a diverse panel of 529 accessions, each genotyped at ∼6.4 million single nucleotide polymorphism loci. We identified 72 loci associated with natural ionomic variations, 32 that are common across locations and 40 that are common within a single location. We identified candidate genes for 42 loci and provide evidence for the causal nature of three genes, the sodium transporter gene Os-HKT1;5 for sodium, Os-MOLYBDATE TRANSPORTER1;1 for molybdenum, and Grain number, plant height, and heading date7 for nitrogen. Comparison of GWAS data from rice versus Arabidopsis (Arabidopsis thaliana) also identified well-known as well as new candidates with potential for further characterization. Our study provides crucial insights into the genetic basis of ionomic variations in rice and serves as an important foundation for further studies on the genetic and molecular mechanisms controlling the rice ionome.
Electrochemical reduction (ER) is a promising approach to safely remove pollutants. However, sluggish reaction kinetics and significant side reactions considerably limit the applicability of this ...green process. Herein, we uncovered the previously ignored role of interfacial hydrophilicity in determining the ER performance through electron microscopy observations, contact angle (CA) analysis, and electrochemical measurements. A Pd/C electrocatalyst forms dense nanopores on the electrode surface, rendering it highly hydrophobic and achieving a CA of up to 145°. This imposes a large mass-transfer barrier for the diffusion of water and pollutants into Pd sites. Moreover, the release of H2 is suppressed, which changes the solid–liquid (Pd–polluted water) interface into a solid–gas (H2)–liquid interface. This further slows down mass transfer and the decontamination process. This dilemma can be easily alleviated by adding hydrophilic polymers like polyethylene glycol to increase hydrophilicity and improve mass transfer. By this way, the activity and Faraday efficiency of Pd/C in the electrochemical hydrodehalogenation of 2,4-dichlorophenol could be increased by 4–5 times. Moreover, this interfacial microenvironment modulation strategy is parallel to other approaches, such as Pd structural engineering, and therefore these strategies can be combined to further increase the electrochemical decontamination performance of electrocatalysts.
In locoregionally advanced nasopharyngeal carcinoma (LANPC) patients, variance of tumor response to induction chemotherapy (ICT) was observed. We developed and validated a novel imaging biomarker to ...predict which patients will benefit most from additional ICT compared with chemoradiotherapy (CCRT) alone.
All patients, including retrospective training (n = 254) and prospective randomized controlled validation cohorts (a substudy of NCT01245959, n = 248), received ICT+CCRT or CCRT alone. Primary endpoint was failure-free survival (FFS). From the multi-parameter magnetic resonance images of the primary tumor at baseline, 819 quantitative 2D imaging features were extracted. Selected key features (according to their interaction effect between the two treatments) were combined into an Induction Chemotherapy Outcome Score (ICTOS) with a multivariable Cox proportional hazards model using modified covariate method. Kaplan-Meier curves and significance test for treatment interaction were used to evaluate ICTOS, in both cohorts.
Three imaging features were selected and combined into ICTOS to predict treatment outcome for additional ICT. In the matched training cohort, patients with a high ICTOS had higher 3-year and 5-year FFS in ICT+CCRT than CCRT subgroup (69.3% vs. 45.6% for 3-year FFS, and 64.0% vs. 36.5% for 5-year FFS; HR = 0.43, 95% CI = 0.25-0.74, p = 0.002), whereas patients with a low ICTOS had no significant difference in FFS between the subgroups (p = 0.063), with a significant treatment interaction (p
< 0.001). This trend was also found in the validation cohort with high (n = 73, ICT+CCRT 89.7% and 89.7% vs. CCRT 61.8% and 52.8% at 3-year and 5-year; HR = 0.17, 95% CI = 0.06-0.51, p < 0.001) and low ICTOS (n = 175, p = 0.31), with a significant treatment interaction (p
= 0.019). Compared with 12.5% and 16.6% absolute benefit in the validation cohort (3-year FFS from 69.9 to 82.4% and 5-year FFS from 63.4 to 80.0% from additional ICT), high ICTOS group in this cohort had 27.9% and 36.9% absolute benefit. Furthermore, no significant survival improvement was found from additional ICT in both groups after stratifying low ICTOS patients into low-risk and high-risks groups, by clinical risk factors.
An imaging biomarker, ICTOS, as proposed, identified patients who were more likely to gain additional survival benefit from ICT+CCRT (high ICTOS), which could influence clinical decisions, such as the indication for ICT treatment.
ClinicalTrials.gov , NCT01245959 . Registered 23 November 2010.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
• In order to gain insights into the transport and distribution of arsenic (As) in intact rice (Oryza sativa) plants and its unloading into the rice grain, we investigated the spatial distribution of ...As and the temporal variation of As concentration in whole rice plants at different growth stages. To the best of our knowledge, this is the first time that such a study has been performed. • Inductively coupled plasma mass spectroscopy (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS were used to analyze total As concentration and speciation. Moreover, synchrotron-based X-ray fluorescence (SXRF) was used to investigate in situ As distribution in the leaf, internode, node and grain. • Total As concentrations of vegetative tissues increased during the 2 wk after flowering. The concentration of dimethylarsinic acid (DMA) in the caryopsis decreased progressively with its development, whereas inorganic As concentration remained stable. The ratios of As content between neighboring leaves or between neighboring internodes were c. 0.6. SXRF revealed As accumulation in the center of the caryopsis during its early development and then in the ovular vascular trace. • These results indicate that there are different controls on the unloading of inorganic As and DMA; the latter accumulated mainly in the caryopsis before flowering, whereas inorganic As was mainly transported into the caryopsis during grain filling. Moreover, nodes appeared to serve as a check-point in As distribution in rice shoots.
Previous studies have shown that the Nodulin 26-like intrinsic membrane protein (NIP) Lsi1 (OsNIP2;1) is involved in arsenite As(III) uptake in rice (Oryza sativa). However, the role of other rice ...NIPs in As(III) accumulation in planta remains unknown. In the present study, we investigated the role OsNIP3;2 in As(III) uptake in rice. When expressed in Xenopus laevis oocytes, OsNIP3;2 showed a high transport activity for As(III). Quantitative real-time RT-PCR showed that the expression of OsNIP3;2 was suppressed by 5 μM As(III), but enhanced by 20 and 100 μM As(III). Transgenic rice plants expressing OsNIP3;2pro-GUS showed that the gene was predominantly expressed in the lateral roots and the stele region of the primary roots. Transient expression of OsNIP3;2:GFP fusion protein in rice protoplasts showed that the protein was localized in the plasma membrane. Knockout of OsNIP3;2 significantly decreased As concentration in the roots, but had little effect on shoot As concentration. Synchrotron microfocus X-ray fluorescence showed decreased As accumulation in the stele of the lateral roots in the mutants compared with wild-type. Our results indicate that OsNIP3;2 is involved in As(III) uptake by lateral roots, but its contribution to As accumulation in the shoots is limited.
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