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1.
Nat Commun ; 13(1): 2222, 2022 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-35468878

RESUMO

Plant salt-stress response involves complex physiological processes. Previous studies have shown that some factors promote salt tolerance only under high transpiring condition, thus mediating transpiration-dependent salt tolerance (TDST). However, the mechanism underlying crop TDST remains largely unknown. Here, we report that ZmSTL1 (Salt-Tolerant Locus 1) confers natural variation of TDST in maize. ZmSTL1 encodes a dirigent protein (termed ZmESBL) localized to the Casparian strip (CS) domain. Mutants lacking ZmESBL display impaired lignin deposition at endodermal CS domain which leads to a defective CS barrier. Under salt condition, mutation of ZmESBL increases the apoplastic transport of Na+ across the endodermis, and then increases the root-to-shoot delivery of Na+ via transpiration flow, thereby leading to a transpiration-dependent salt hypersensitivity. Moreover, we show that the ortholog of ZmESBL also mediates CS development and TDST in Arabidopsis. Our study suggests that modification of CS barrier may provide an approach for developing salt-tolerant crops.


Assuntos
Arabidopsis , Tolerância ao Sal , Arabidopsis/genética , Arabidopsis/metabolismo , Parede Celular/metabolismo , Raízes de Plantas/metabolismo , Tolerância ao Sal/genética , Zea mays/metabolismo
2.
Materials (Basel) ; 15(3)2022 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-35161186

RESUMO

The chemical and mineral components of the leaching residues obtained during the leaching of inert mineral product (IMP) and two samples of divalent metal oxide continuous solid solution (RO phase) by acetum at 20 °C were analyzed to reveal the selective leaching characteristics of the chemical and mineral components in steel slag, and clarify the leaching rates and differences of MgO and FeO in the RO phase. The results indicated that the content of total Fe (TFe) in the leaching residue increased, whereas the contents of CaO, SiO2, and MgO decreased during the leaching of the inert mineral product by acetum. Fe3O4 was insoluble in acetum. The leaching rates of the RO phase and metallic Fe were very low, while those of calcium silicate (C2S + C3S) and dicalcium ferrite (C2F) were quite high. MgO and FeO in the RO phase continuously leached over time, and the leaching rate of MgO reached 1.9 times that of FeO. Therefore, during the leaching of the RO phase by acetum, the FeO content increased, whereas the MgO content decreased. In conclusion, acetum leaching can effectively improve the TFe content of the RO phase and the inert mineral product.

3.
Plant Physiol ; 188(4): 2085-2100, 2022 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-35134219

RESUMO

Stomatal movement is essential for plants to optimize transpiration and therefore photosynthesis. Rapid changes in the stomatal aperture are accompanied by adjustment of vacuole volume and morphology in guard cells (GCs). In Arabidopsis (Arabidopsis thaliana) leaf epidermis, stomatal development undergoes a cell-fate transition including four stomatal lineage cells: meristemoid, guard mother cell, young GC, and GC. Little is known about the mechanism underlying vacuole dynamics and vacuole formation during stomatal development. Here, we utilized whole-cell electron tomography (ET) analysis to elucidate vacuole morphology, formation, and development in different stages of stomatal lineage cells at nanometer resolution. The whole-cell ET models demonstrated that large vacuoles were generated from small vacuole stepwise fusion/maturation along stomatal development stages. Further ET analyses verified the existence of swollen intraluminal vesicles inside distinct vacuoles at certain developmental stages of stomatal lineage cells, implying a role of multivesicular body fusion in stomatal vacuole formation. Collectively, our findings demonstrate a mechanism mediating vacuole formation in Arabidopsis stomatal development and may shed light on the role of vacuoles in stomatal movement.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteínas de Arabidopsis/genética , Tomografia com Microscopia Eletrônica , Estômatos de Plantas , Vacúolos
4.
Opt Express ; 30(2): 957-965, 2022 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-35209273

RESUMO

Reverse design is a frontier direction in the optical research field. In this work, reverse design is applied to the design of terahertz devices. We have employed direct binary search (DBS) and binary particle swarm optimization (BPSO) algorithms to design pixel-type terahertz band-pass filters, respectively. Through a comparative analysis of the designed devices, we found that BPSO algorithm converged faster than DBS algorithm, and the device performance is better on out-of-band suppression. We have fabricated a sample utilizing femtosecond laser micromachining and characterized it by terahertz time-domain spectroscopy. The experimental results were consistent with the finite difference time domain (FDTD) simulation. Our method can simultaneously optimize multiple characteristics of the band-pass filters, including the peak transmittance, out-of-band transmittance, bandwidth, and polarization stability, which can not be achieved by traditional optical design methods.

5.
J Hazard Mater ; 429: 128294, 2022 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-35065309

RESUMO

The abuse of cephalosporins poses a serious threat to human health and the ecological environment. In this work, cephalosporinase (AmpC enzyme) and Prussian blue (PB) crystals were encapsulated into ZIF-8 metal-organic frameworks (MOFs), and a photothermal AmpC/PB@ZIF-8 MOFs (APZ) nanocatalyst was prepared for the catalytic degradation of cephalosporin. The temperature of the APZ catalytic degradation system can be regulated by irradiation with near infrared light due to the photothermal effect of PB, and then, the activity of the APZ biocatalyst is significantly enhanced. Thereby, the degradation efficiency of cefuroxime can reach to 96%, and the degradation kinetic rate of cefuroxime augmented 4.5-fold comparing with that catalyzed by free enzyme. Moreover, encapsulation of the enzyme and PB can increase the affinity and charge transfer efficiency between APZ and substrate molecules, which can also improve the degradation efficiency of cephalosporins. Catalytic degradation pathways for three generations of cephalosporins were proposed based on their degradation products. The dual-enhancer biocatalyst based on the photothermal effect and immobilization of the PB and enzyme can significantly enhance the activity and stability of the enzyme, and it can also be recycled. Therefore, the biocatalyst has potential applications for the effective degradation of cephalosporins in the environment.


Assuntos
Cefalosporinas , Raios Infravermelhos , Catálise , Humanos , Temperatura
6.
Brief Bioinform ; 23(1)2022 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-34676389

RESUMO

The employment of doubled-haploid (DH) technology in maize has vastly accelerated the efficiency of developing inbred lines. The selection of superior lines has to rely on genotypes with genomic selection (GS) model, rather than phenotypes due to the high expense of field phenotyping. In this work, we implemented 'genome optimization via virtual simulation (GOVS)' using the genotype and phenotype data of 1404 maize lines and their F1 progeny. GOVS simulates a virtual genome encompassing the most abundant 'optimal genotypes' or 'advantageous alleles' in a genetic pool. Such a virtually optimized genome, although can never be developed in reality, may help plot the optimal route to direct breeding decisions. GOVS assists in the selection of superior lines based on the genomic fragments that a line contributes to the simulated genome. The assumption is that the more fragments of optimal genotypes a line contributes to the assembly, the higher the likelihood of the line favored in the F1 phenotype, e.g. grain yield. Compared to traditional GS method, GOVS-assisted selection may avoid using an arbitrary threshold for the predicted F1 yield to assist selection. Additionally, the selected lines contributed complementary sets of advantageous alleles to the virtual genome. This feature facilitates plotting the optimal route for DH production, whereby the fewest lines and F1 combinations are needed to pyramid a maximum number of advantageous alleles in the new DH lines. In summary, incorporation of DH production, GS and genome optimization will ultimately improve genomically designed breeding in maize. Short abstract: Doubled-haploid (DH) technology has been widely applied in maize breeding industry, as it greatly shortens the period of developing homozygous inbred lines via bypassing several rounds of self-crossing. The current challenge is how to efficiently screen the large volume of inbred lines based on genotypes. We present the toolbox of genome optimization via virtual simulation (GOVS), which complements the traditional genomic selection model. GOVS simulates a virtual genome encompassing the most abundant 'optimal genotypes' in a breeding population, and then assists in selection of superior lines based on the genomic fragments that a line contributes to the simulated genome. Availability of GOVS (https://govs-pack.github.io/) to the public may ultimately facilitate genomically designed breeding in maize.


Assuntos
Melhoramento Vegetal , Zea mays , Genótipo , Haploidia , Fenótipo , Melhoramento Vegetal/métodos , Zea mays/genética
7.
J Chromatogr A ; 1659: 462648, 2021 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-34739963

RESUMO

A hydrophilic metal-organic network based on Ti4+ and dual natural ligand, tannic acid (TA) and phytic acid (PA), has been developed to enrich phosphopeptides from complex bio-samples prior to liquid chromatography-mass spectrometric analysis. Due to the strong chelation ability of TA and PA, abundant Ti4+ can be immobilized in the material, forming hydrophilic network by one-step coordination-driven self-assembly approach. The sorbent, TA-Ti-PA@Fe3O4, exhibited satisfactory selectivity for the phosphopeptides in the tryptic digest of ß-casein, and can eliminate the interference components in 1000-fold excess of bovine serum albumin. The adsorption capacity of the sorbents for phosphopeptides was up to 35.2 mg g-1 and the adsorbing equilibrium can be reached in 5 min. The adsorbing mechanism has been investigated and the results indicated that the Ti4+ in forms of [Ti(f-TA)(H2O)4]2+, [Ti(f-PA)(H2O)4]2+ and Ti(f-PA)2(H2O)2 may play an important role in the adsorption process. The sorbent of the TA-Ti-PA@Fe3O4 has been applied to enrichment of the phosphopeptides in tryptic digest of rat liver lysate, and 3408 phosphopeptides have been identified, while the numbers of the identified phosphopeptides were 2730 and 1217 when the sample was enriched by the commercial TiO2 and Fe3+-IMAC kit, respectively. This work provides a strategy to enrich phosphopeptides from complex samples and shows great potential application in phosphoproteome research.


Assuntos
Fosfopeptídeos , Titânio , Animais , Cromatografia de Afinidade , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Ratos
8.
Nat Plants ; 7(10): 1335-1346, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34621047

RESUMO

Plants live as sessile organisms with large-scale gene duplication events and subsequent paralogue divergence during evolution. Notably, plant paralogues are expressed tissue-specifically and fine-tuned by phytohormones during various developmental processes. The coat protein complex II (COPII) is a highly conserved vesiculation machinery mediating protein transport from the endoplasmic reticulum to the Golgi apparatus in eukaryotes1. Intriguingly, Arabidopsis COPII paralogues greatly outnumber those in yeast and mammals2-6. However, the functional diversity and underlying mechanism of distinct COPII paralogues in regulating protein endoplasmic reticulum export and coping with various adverse environmental stresses are poorly understood. Here we characterize a novel population of COPII vesicles produced in response to abscisic acid, a key phytohormone regulating abiotic stress responses in plants. These hormone-induced giant COPII vesicles are regulated by an Arabidopsis-specific COPII paralogue and carry stress-related channels/transporters for alleviating stresses. This study thus provides a new mechanism underlying abscisic acid-induced stress responses via the giant COPII vesicles and answers a long-standing question on the evolutionary significance of gene duplications in Arabidopsis.


Assuntos
Ácido Abscísico/farmacologia , Arabidopsis/metabolismo , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Retículo Endoplasmático/metabolismo , Ácido Abscísico/metabolismo
9.
Front Genet ; 12: 732812, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34567082

RESUMO

African bermudagrass (Cynodon transvaalensis Burtt-Davy) is an important warm-season turfgrass and forage grass species. Heat shock protein 20 (HSP20) is a diverse, ancient, and important protein family. To date, HSP20 genes have not been characterized genome-widely in African bermudagrass. Here, we confirmed 41 HSP20 genes in African bermudagrass genome. On the basis of the phylogenetic tree and cellular locations, the HSP20 proteins were classified into 12 subfamilies. Motif composition was consistent with the phylogeny. Moreover, we identified 15 pairs of paralogs containing nine pairs of tandem duplicates and six pairs of WGD/segmental duplicates of HSP20 genes. Unsurprisingly, the syntenic genes revealed that African bermudagrass had a closer evolutionary relationship with monocots (maize and rice) than dicots (Arabidopsis and soybean). The expression patterns of HSP20 genes were identified with the transcriptome data under abiotic stresses. According to the expression profiles, HSP20 genes could be clustered into three groups (Groups I, II, and III). Group I was the largest, and these genes were up-regulated in response to heat stress as expected. In Group II, one monocot-specific HSP20, CtHSP20-14 maintained higher expression levels under optimum temperature and low temperature, but not high temperature. Moreover, a pair of WGD/segmental duplicates CtHSP20-9 and CtHSP20-10 were among the most conserved HSP20s across different plant species, and they seemed to be positively selected in response to extreme temperatures during evolution. A total of 938 cis-elements were captured in the putative promoters of HSP20 genes. Almost half of the cis-elements were stress responsive, indicating that the expression pattern of HSP20 genes under abiotic stresses might be largely regulated by the cis-elements. Additionally, three-dimensional structure simulations and protein-protein interaction networks were incorporated to resolve the function mechanism of HSP20 proteins. In summary, the findings fulfilled the HSP20 family analysis and could provide useful information for further functional investigations of the specific HSP20s (e.g., CtHSP20-9, CtHSP20-10, and CtHSP20-14) in African bermudagrass.

10.
Micromachines (Basel) ; 12(9)2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34577736

RESUMO

The reverse design method (RDM) is a frontier direction in the optical research field. In this work, RDM is applied to the design of terahertz demultiplexers, including two-port and three-port terahertz demultiplexers, with areas of 3 mm × 3 mm and 5 mm × 5 mm, respectively. The Finite-Difference Time-Domain (FDTD) simulation results show that the terahertz waves at frequencies of 0.5 THz and 0.417 THz can be well separated by the two-port demultiplexer, and the transmittances of the two outputs reach as high as 0.75 after bandwidth optimization. Meanwhile, the three-port terahertz demultiplexer can have terahertz waves separated from three Ports, and the crosstalk between adjacent channels is less than -18 dB.

11.
Genome Biol ; 22(1): 271, 2021 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-34544450

RESUMO

LightGBM is an ensemble model of decision trees for classification and regression prediction. We demonstrate its utility in genomic selection-assisted breeding with a large dataset of inbred and hybrid maize lines. LightGBM exhibits superior performance in terms of prediction precision, model stability, and computing efficiency through a series of benchmark tests. We also assess the factors that are essential to ensure the best performance of genomic selection prediction by taking complex scenarios in crop hybrid breeding into account. LightGBM has been implemented as a toolbox, CropGBM, encompassing multiple novel functions and analytical modules to facilitate genomically designed breeding in crops.


Assuntos
Produtos Agrícolas/genética , Aprendizado de Máquina , Melhoramento Vegetal/métodos , Software , Árvores de Decisões , Estudo de Associação Genômica Ampla , Genômica/métodos , Polimorfismo de Nucleotídeo Único , Zea mays/genética
12.
Cell Death Discov ; 7(1): 222, 2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34453042

RESUMO

Liver is the most common site where metastatic lesions of colorectal cancer (CRC) arise. Although researches have shown mutations in driver genes, copy number variations (CNV) and alterations in relevant signaling pathways promoted the tumor evolution and immune escape during colorectal liver metastasis (CLM), the underlying mechanism remains largely elusive. Tumor and matched metastatic tissues were collected from 16 patients diagnosed with colorectal cancer and subjected to whole-exome sequencing (WES) and RNA sequencing (RNA-seq) for studying colorectal cancer clonal evolution and immune escape during CLM. Shared somatic mutations between primary and metastatic tissues with a commonly observed subclonal-clonal (S-C) changing pattern indicated a common clonal origin between two lesions. The recurrent mutations with S-C changing pattern included those in KRAS, SYNE1, CACNA1H, PCLO, FBXL2, and DNAH11. The main CNV events underwent clonal-clonal evolution (20q amplification (amp), 17p deletion (del), 18q del and 8p del), subclonal-clonal evolution (8q amp, 13q amp, 8p del) and metastasis-specific evolution (8q amp) during the process of CLM. In addition, we revealed a potential mechanism of tumor cell immune escape by analyzing human leukocytes antigens (HLA) related clonal neoantigens and immune cell components in CLM. Our study proposed a novel liver metastasis-related evolutionary process in colorectal cancer and emphasized the theory of neo-immune escape in colorectal liver metastasis.

13.
Artigo em Inglês | MEDLINE | ID: mdl-34347595

RESUMO

In recent years, reinforcement learning has achieved excellent results in low-dimensional static action spaces such as games and robotics. However, the action space is usually composite, composed of multiple sub-action with different functions, and time-varying for practical tasks. The existing sub-actions might be out of control due to the external environment, while unseen sub-actions can be added to the current system. To solve the robustness and transferability problems in time-varying composite action spaces, we propose a structured cooperative reinforcement learning algorithm based on the centralized critic and decentralized actor framework, called SCORE. We model the single-agent problem with composite action space as a fully cooperative partially observable stochastic game and further employ a graph attention network to capture the dependencies between heterogeneous sub-actions. To promote tighter cooperation between the decomposed heterogeneous agents, SCORE introduces a hierarchical variational autoencoder, which maps the heterogeneous sub-action space into a common latent action space. We also incorporate an implicit credit assignment structure into the SCORE to overcome the multi-agent credit assignment problem in the fully cooperative partially observable stochastic game. Performance experiments on the proof-of-concept task and precision agriculture task show that SCORE has significant advantages in robustness and transferability for time-varying composite action space.

14.
Artigo em Inglês | MEDLINE | ID: mdl-34314874

RESUMO

Limited knowledge of genomic diversity and functional genes associated with the traits of soybean varieties has resulted in slow progress in breeding. This study aimed to sequence the genome of 250 soybean landraces and cultivars from China, America, and Europe and to investigate their population structure, genetic diversity and architecture, and selective sweep regions of accessions. Five novel agronomically important genes were identified, and the effects of functional mutations in respective genes were examined. The candidate genes GSTT1, GL3, and GSTL3 associated with the isoflavone content, CKX3 associated with yield traits, and CYP85A2 associated with both architecture and yield traits were found. The phenotype-gene network analysis revealed that hub nodes played a role in complex phenotypic associations. This study described novel agronomic trait-associated genes and a complex genetic network, providing a valuable resource for future soybean molecular breeding.

15.
Genome Biol ; 22(1): 148, 2021 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-33971930

RESUMO

BACKGROUND: In maize hybrid breeding, complementary pools of parental lines with reshuffled genetic variants are established for superior hybrid performance. To comprehensively decipher the genetics of heterosis, we present a new design of multiple linked F1 populations with 42,840 F1 maize hybrids, generated by crossing a synthetic population of 1428 maternal lines with 30 elite testers from diverse genetic backgrounds and phenotyped for agronomic traits. RESULTS: We show that, although yield heterosis is correlated with the widespread, minor-effect epistatic QTLs, it may be resulted from a few major-effect additive and dominant QTLs in early developmental stages. Floral transition is probably one critical stage for heterosis formation, in which epistatic QTLs are activated by paternal contributions of alleles that counteract the recessive, deleterious maternal alleles. These deleterious alleles, while rare, epistatically repress other favorable QTLs. We demonstrate this with one example, showing that Brachytic2 represses the Ubiquitin3 locus in the maternal lines; in hybrids, the paternal allele alleviates this repression, which in turn recovers the height of the plant and enhances the weight of the ear. Finally, we propose a molecular design breeding by manipulating key genes underlying the transition from vegetative-to-reproductive growth. CONCLUSION: The new population design is used to dissect the genetic basis of heterosis which accelerates maize molecular design breeding by diminishing deleterious epistatic interactions.


Assuntos
Vigor Híbrido/genética , Zea mays/genética , Simulação por Computador , Cruzamentos Genéticos , Embaralhamento de DNA , Epistasia Genética , Flores/genética , Flores/fisiologia , Estudo de Associação Genômica Ampla , Genótipo , Modelos Genéticos , Herança Multifatorial/genética , Fenótipo , Melhoramento Vegetal , Locos de Características Quantitativas/genética
16.
Hortic Res ; 8(1): 93, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33931599

RESUMO

Cynodon species can be used for multiple purposes and have high economic and ecological significance. However, the genetic basis of the favorable agronomic traits of Cynodon species is poorly understood, partially due to the limited availability of genomic resources. In this study, we report a chromosome-scale genome assembly of a diploid Cynodon species, C. transvaalensis, obtained by combining Illumina and Nanopore sequencing, BioNano, and Hi-C. The assembly contains 282 scaffolds (~423.42 Mb, N50 = 5.37 Mb), which cover ~93.2% of the estimated genome of C. transvaalensis (~454.4 Mb). Furthermore, 90.48% of the scaffolds (~383.08 Mb) were anchored to nine pseudomolecules, of which the largest was 60.78 Mb in length. Evolutionary analysis along with transcriptome comparison provided a preliminary genomic basis for the adaptation of this species to tropical and/or subtropical climates, typically with dry summers. The genomic resources generated in this study will not only facilitate evolutionary studies of the Chloridoideae subfamily, in particular, the Cynodonteae tribe, but also facilitate functional genomic research and genetic breeding in Cynodon species for new leading turfgrass cultivars in the future.

17.
Nat Commun ; 12(1): 2181, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33846350

RESUMO

Regulation of stomatal movement is critical for plant adaptation to environmental stresses. The microtubule cytoskeleton undergoes disassembly, which is critical for stomatal closure in response to abscisic acid (ABA). However, the mechanism underlying this regulation largely remains unclear. Here we show that a ubiquitin-26S proteasome (UPS)-dependent pathway mediates microtubule disassembly and is required for ABA-induced stomatal closure. Moreover, we identify and characterize the ubiquitin E3 ligase MREL57 (MICROTUBULE-RELATED E3 LIGASE57) and the microtubule-stabilizing protein WDL7 (WAVE-DAMPENED2-LIKE7) in Arabidopsis and show that the MREL57-WDL7 module regulates microtubule disassembly to mediate stomatal closure in response to drought stress and ABA treatment. MREL57 interacts with, ubiquitinates and degrades WDL7, and this effect is clearly enhanced by ABA. ABA-induced stomatal closure and microtubule disassembly are significantly suppressed in mrel57 mutants, and these phenotypes can be restored when WDL7 expression is decreased. Our results unravel UPS-dependent mechanisms and the role of an MREL57-WDL7 module in microtubule disassembly and stomatal closure in response to drought stress and ABA.


Assuntos
Ácido Abscísico/farmacologia , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Microtúbulos/metabolismo , Estômatos de Plantas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Arabidopsis/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Microtúbulos/efeitos dos fármacos , Modelos Biológicos , Mutação/genética , Estômatos de Plantas/citologia , Estômatos de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas , Ligação Proteica/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/metabolismo , Ubiquitina/metabolismo , Ubiquitinação/efeitos dos fármacos
18.
Opt Express ; 29(6): 9261-9268, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33820358

RESUMO

Plasma edges in metals typically occur in the visible range, producing characteristic colors of metals. In a lightly doped semiconductor, the plasma edge can occur in the terahertz (THz) frequency range. Due to low scattering rates and variable electron densities in semiconductors, such THz plasma edges can be extremely sharp and greatly tunable. Here, we show that an ultrasharp THz plasma edge exists in a lightly n-doped InSb crystal with a record-high transmittance slope of 80 dB/THz. The frequency at which this sharp edge happens can be readily tuned by changing the temperature, electron density, scattering rate, and sample thickness. The edge frequency exhibited a surprising increase with decreasing temperature below 15 K, which we explain as a result of a weak-to-strong transition in the scattering rate, going from ωτ  ≫ 1 to ωτ âˆ¼ 1. These results indicate that doped narrow-gap semiconductors provide a versatile platform for manipulating THz waves in a controllable manner, especially as a high-pass filter with an unprecedented on/off ratio.

19.
New Phytol ; 230(6): 2355-2370, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33666235

RESUMO

The farmland of the world's main corn-producing area is increasingly affected by salt stress. Therefore, the breeding of salt-tolerant cultivars is necessary for the long-term sustainability of global corn production. Previous studies have shown that natural maize varieties display a large diversity of salt tolerance, yet the genetic variants underlying such diversity remain poorly discovered and applied, especially those mediating the tolerance to salt-induced osmotic stress (SIOS). Here we report a metabolomics-driven understanding and genetic improvement of maize SIOS tolerance. Using a LC-MS-based untargeted metabolomics approach, we profiled the metabolomes of 266 maize inbred lines under control and salt conditions, and then identified 37 metabolite biomarkers of SIOS tolerance (METO1-37). Follow-up metabolic GWAS (mGWAS) and genotype-to-phenotype modeling identified 10 candidate genes significantly associating with the SIOS tolerance and METO abundances. Furthermore, we validated that a citrate synthase, a glucosyltransferase and a cytochrome P450 underlie the genotype-METO-SIOS tolerance associations, and showed that their favorable alleles additively improve the SIOS tolerance of elite maize inbred lines. Our study provides a novel insight into the natural variation of maize SIOS tolerance, which boosts the genetic improvement of maize salt tolerance, and demonstrates a metabolomics-based approach for mining crop genes associated with this complex agronomic trait.


Assuntos
Melhoramento Vegetal , Zea mays , Metabolômica , Pressão Osmótica , Fenótipo , Zea mays/genética
20.
J Hazard Mater ; 414: 125549, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33676260

RESUMO

The pollution caused by the abuse of antibiotics has posed a serious threat to the ecological environment and human health, so development of effective strategies for degradation and disposal of antibiotic residues is urgently needed. In this work, penicillinase, a kind of ß-lactamase, was immobilized into zeolitic imidazolate framework-8 (ZIF-8) by self-assembly method and the catalytic performance of the ß-lactamase@ZIF-8 porous materials for degradation of penicillins has been investigated by high performance liquid chromatography coupled with mass spectrometry. The results illustrated that the catalytic activity of the encapsulated enzyme was significantly enhanced comparing with that of free enzyme. Meanwhile, the ß-lactamase@ZIF-8 exhibited excellent stability under denaturing conditions including high temperature, organic solvent and the enzyme inhibitor. The catalytic degradation mechanism of the ß-lactamase@ZIF-8 for penicillins has been probed and verified, and it has been found that the Zn (II) ion on ZIF-8 frameworks could form the complex with the target molecule, which weakened the bond of the four-membered ß-lactam ring in the penicillin molecule, and thus enhanced the degradation efficiency of the enzyme. This work provided a promising strategy for eliminating the penicillin residues in water environment.


Assuntos
Estruturas Metalorgânicas , Zeolitas , Cromatografia Líquida de Alta Pressão , Humanos , Penicilinas , beta-Lactamases
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