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1.
Dev Comp Immunol ; 126: 104264, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34551359

RESUMO

The ß-defensins are important components of the vertebrate innate immune system. While mammalian ß-defensins have wide-ranging antibacterial and immunomodulatory activities, those of amphibians remain largely uncharacterised. In this study, ß-defensin cDNA was identified from the skin transcriptome of the Chinese spiny frog Quasipaa spinosa. This ß-defensin (QS-BD) consists of a signal and a mature peptide. Sequence alignments with other amphibian ß-defensins showed conservation of the functional mature peptide and that its closest relative is ß-defensin from Zhangixalus puerensis. Synthetic QS-BD showed antibacterial activity against Vibrio vulnificus, Vibrio harveyi, Streptococcus iniae, and Aeromonas hydrophila. QS-BD showed bactericidal activity by destroying the cell membrane integrity, but did not hydrolyse genomic DNA. QS-BD treatment promoted respiratory bursts and upregulated the expression of interleukin-1ß and tumour necrosis factor-α in the murine leukemic monocyte/macrophage cell line RAW264.7. This is the first demonstration of immunomodulatory activity by an amphibian ß-defensin.

2.
J Hazard Mater ; 422: 126846, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34416702

RESUMO

Zeolitic imidazole frameworks (ZIFs) have attracted a considerable amount of attention for use in environmental applications (e.g., pollutant adsorption and photocatalysis in water treatments). The environmental stability and toxicity of ZIFs are key prerequisites for their practical applications, but information about these factors is largely lacking. The present work finds that pristine ZIFs (ZIF-8 and ZIF-67) photodegrade from frame structures into two-dimensional nanosheets and are oxidized to zinc carbonate (ZIF-8) and Co3O4 (ZIF-67) under visible-light irradiation. The photoinduced electrons, holes and free radicals promote dissolution of the metal cores and organic ligands, leading to collapse of the frame structure. The photodegradation of ZIF-8 alleviates developmental inhibition, oxidative stress, plasmolysis, and photosynthetic toxicity, while the photodegradation of ZIF-67 aggravates nanotoxicity. The integration of metabolomics and transcriptomics analysis reveals that unsaturated fatty acid biosynthesis and metal ion-binding transcription contribute to the altered toxicity of ZIF photodegradation. These findings highlight the roles of photodegradation in structural transformation and alteration of the toxicity of ZIFs, alarming the study of pristine metal-organic frameworks (MOFs).

3.
Nano Lett ; 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34812644

RESUMO

Nanomaterials show great potential for the treatment of bacterial infections, but their effects remain limited by low antibacterial efficiency and immune clearance. Facet-dependent nanozymes coated with pathogen receptor membranes were fabricated, providing an approach for producing superphotothermal antibacterial nanomaterials with high biocompatibility and low immune clearance. (100)- and (112)-Faceted CuFeSe2 presented excellent photothermal conversion efficiency (46%). However, the peroxidase-like activity of (100)-faceted CuFeSe2 enhanced the decomposition of H2O2 to hydroxyl radicals (•OH) and was markedly greater than that of (112)-faceted CuFeSe2, with nearly 100% of Staphylococcus aureus being killed under near-infrared (NIR) irradiation. Importantly, bacteria-pretreated immune membranes (i.e., pathogen receptor membranes) coated with CuFeSe2 exhibited superior S. aureus-binding ability, presented obvious immune-evading capability, and resulted in targeted delivery to infected sites. As a proof-of-principle demonstration, these findings hold promise for the use of pathogen receptor membrane-coated facet-dependent nanomaterials in clinical applications and the treatment of bacterial infections.

4.
BMC Plant Biol ; 21(1): 550, 2021 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-34809576

RESUMO

BACKGROUND: Pineapple (Ananas comosus L. Merr.) is the third most important tropical fruit in China. In other crops, farmers can easily judge the nutritional requirements from leaf color. However, concerning pineapple, it is difficult due to the variation in leaf color of the cultivated pineapple varieties. A detailed understanding of the mechanisms of nutrient transport, accumulation, and assimilation was targeted in this study. We explored the D-leaf nitrogen (N), phosphorus (P), and potassium (K) contents, transcriptome, and metabolome of seven pineapple varieties. RESULTS: Significantly higher N, P, and K% contents were observed in Bali, Caine, and Golden pineapple. The transcriptome sequencing of 21 libraries resulted in the identification of 14,310 differentially expressed genes in the D-leaves of seven pineapple varieties. Genes associated with N transport and assimilation in D-leaves of pineapple was possibly regulated by nitrate and ammonium transporters, and glutamate dehydrogenases play roles in N assimilation in arginine biosynthesis pathways. Photosynthesis and photosynthesis-antenna proteins pathways were also significantly regulated between the studied genotypes. Phosphate transporters and mitochondrial phosphate transporters were differentially regulated regarding inorganic P transport. WRKY, MYB, and bHLH transcription factors were possibly regulating the phosphate transporters. The observed varying contents of K% in the D-leaves was associated to the regulation of K+ transporters and channels under the influence of Ca2+ signaling. The UPLC-MS/MS analysis detected 873 metabolites which were mainly classified as flavonoids, lipids, and phenolic acids. CONCLUSIONS: These findings provide a detailed insight into the N, P, K% contents in pineapple D-leaf and their transcriptomic and metabolomic signatures.

5.
Chem Commun (Camb) ; 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34816834

RESUMO

Structural transformations of nanoclusters provide a platform to tune their properties and understand the fundamental science due to their intimate structure-property correlation. Here, we present an alkynyl ligand-exchange induced growth of atomically precise silver(I) clusters, which are particularly of interest because of their luminescence response at room temperature. SCXRD and UV-vis map out the growth steps of the cluster from [Ag32S3(CCBut)23]3+ featuring a pseudo-D3h concave Ag32S3 to [Ag45S6(CCPhBr)32]+ with a pseudo-Oh core-shell Ag9S6@Ag24@Ag12, which is driven by a thermodynamic route under the disruption of ligands. To our knowledge, the findings in this work establish the first example of ligand-exchange as a versatile tool for tuning the size and luminescence of semiconductor silver(I) clusters.

6.
Stem Cells Int ; 2021: 9941733, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34725550

RESUMO

SOX12 plays a role in promoting the growth of some tumors; however, its role in osteosarcoma remains unclear. From gene expression omnibus (GEO) and tumor alterations relevant for genomics-driven therapy (TARGET) databases, Kaplan-Meier analyses were conducted to establish relationships between SOX12 expression and osteosarcoma survival and recurrence in osteosarcoma patients. We also performed in vitro and in vivo assays to determine SOX12 function in osteosarcoma etiology. SOX12 expression was increased in osteosarcoma; high SOX12 expression levels were related to a poor prognosis and a high disease recurrence in patients. Moreover, SOX12 expression in osteosarcoma cell lines was increased, similar to osteosarcoma cancer stem cells. We also observed that SOX12 knockdown inhibited the spheroidization and expression of stemness markers in osteosarcoma cells and tumor formation in nude mice. In addition, SOX12 knockdown inhibited JAGGED1 and HES1 expression. Similarly, JAGGED1 knockdown also inhibited the formation of osteosarcoma cancer stem cells into pellets and reduced the expression of stemness markers and tumor formation capabilities in nude mice. Finally, during SOX12 knockdown, JAGGED1 overexpression rescued osteosarcoma cells from spheroidizing. SOX12 promotes stem cell-like phenotypes and osteosarcoma tumor growth by upregulating JAGGED1.

7.
Nanomaterials (Basel) ; 11(11)2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34835650

RESUMO

A europium(III) hybrid material Eu(tta)3bpdc-SiO2@mTiO2 (Htta = 2-thenoyltrifluoroacetone, H2bpdc = 2,2'-bipyridine-3,3'-dicarboxylic acid) was successfully designed and synthesized by the covalent grafting complex Eu(tta)3bpdc to SiO2@mTiO2 core-shell nanosphere. The FT-IR, PXRD, XPS, TEM, HRTEM, SAED, TGA and PL were performed to characterize these materials. The results indicate that core-shell nanosphere structure and anatase crystallites of SiO2@mTiO2 are retained well after grafting the europium complex. Hybrid material Eu(tta)3bpdc-SiO2@mTiO2 displays uniform nanosphere structure, bright red color and long lifetime, which can serve as a multicolor emission material modulated by using Al3+ ions via the cation exchange approach under a single-wavelength excitation. To the best of our knowledge, this work is the first multicolor emissive sensor for Al3+ ions based on the lanthanide hybrid material.

8.
Appl Microbiol Biotechnol ; 105(20): 7997-8007, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34596723

RESUMO

Agaricus bisporus is the most widely cultivated edible mushroom in the world. Strain quality has an important influence on the yield of A. bisporus, with strains that exhibit aging being a common problem during cultivation. However, little is known about the aging mechanisms of A. bisporus strain. In this study, the normal A. bisporus As2796 strain was compared to the aging A. bisporus As2796Y strain (which was previously discovered during cultivation). In the aging As2796Y mycelia, the mycelial growth rate and fruiting body yield were decreased and the chitin level and cell wall thickness were increased. Additionally, intracellular vacuoles increased, there was cytoplasmic shrinkage, and the sterol level which stabilizes the cell membrane decreased, which led to cytoplasmic outflow and the exudation of a large amount of yellow water from the mycelia. Additionally, there was increased electrolyte leakage. Furthermore, gas chromatography-mass spectrometry (GC/MS) was used to profile the metabolic changes in the aging As2796Y mycelia compared to the normal As2796 mycelia. A total of 52 differential metabolites were identified (75% were downregulated and 25% were upregulated in As2796Y). The reduction of many metabolites decreased the mycelial viability and the ability to maintain cell stability. Overall, this study is the first to report on the morphologic and metabolic changes in aged A. bisporus mycelia, which will aid future research on the mechanisms underlying A. bisporus mycelial aging.Key points• Aging of Agaricus bisporus strains will greatly reduce the fruiting body yield.• Aging of Agaricus bisporus strains can significantly change the cell structure of mycelia.• Many metabolites in the mycelium of aging spawn As2796Y significantly changed.


Assuntos
Agaricus , Ascomicetos , Parede Celular , Micélio
9.
Natl Sci Rev ; 8(4): nwab006, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34676097

RESUMO

After a short recovery period, COVID-19 reinfections could occur in convalescent patients, even those with measurable levels of neutralizing antibodies. Effective vaccinations and protective public health measures are recommended for the convalescent COVID-19 patients.

10.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 52(5): 832-838, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34622601

RESUMO

Objective: To study the distributional characteristics of allergens in children with allergic diseases in Shaanxi province. Methods: A total of 4 622 children diagnosed with allergic diseases in the Asthma Center, Department of Pediatrics, Xijing Hospital from March 2015 to February 2019 were selected. Serum allergen-specific immunoglobulin E (sIgE) of 19 common kinds of allergens were examined with enzyme-linked immunosorbent assay (ELISA). The children were divided into different groups according to sex, age and geographical regions, and the distributional characteristics of allergens of the different groups were compared. Results: The overall positive rate for the 19 allergens of the 4 622 children was 62.8%. The ranking of the positive rates for individual allergens from high to low were as follows: 24.2% for milk, 18.0% for mold mix, 16.7% for dog dander, 16.4% for house dust mite, 11.7% for cat dander, 10.7% for cashew, 10.6% for weed pollen, 8.8% for egg white, 7.8% for house dust, 7.7% for tree pollen, 5.6% for amaranth, 4.9% for mulberry tree, 3.6% for mango, 3.2% for beef, 2.8% for cockroach, 2.1% for crab, 1.5% for shrimp, 0.8% for pineapple, and 0.3% for shellfish. Analysis based on sex showed that the allergen positive rates in boys were higher than those in girls. Analysis by age difference showed that generally the positive rates for inhaled allergens increased along with the increase in patient age, while the positive rates for ingested allergens decreased along with the increase in patient age. Analysis by geographical regions showed that the positive rate of house dust mite in the patients from the southern part of Shaanxi, the positive rate of weed pollen in the patients from the northern part of Shaanxi and the positive rates of milk and egg white in the patients from the central part of Shaanxi were higher than those in other areas. The cluster analysis and correlation analysis showed that the 19 allergens could be roughly divided into 4 categories. There were moderate correlations among tree pollen, mulberry tree and amaranth. There were moderate correlations among mulberry tree, mango and amaranth. There was moderate correlation between shrimp and crab, and there were mild or weak correlations among most of the other allergens. Conclusion: Among the 4 622 children with allergic diseases in Shaanxi Province who were treated in the Asthma Center, Department of Pediatrics, Xijing Hospital, male patients showed higher sensitivity to allergens. The positive rates of inhaled allergens increased, while the positive rates of ingested allergens decreased with increase in patient age. There were regional differences in the distribution of allergens. Some allergens were correlated with each other, which may be related to cross-reaction.


Assuntos
Asma , Hipersensibilidade , Alérgenos , Animais , Asma/epidemiologia , Gatos , Bovinos , Criança , Cães , Poeira , Humanos , Imunoglobulina E , Masculino
11.
Artigo em Inglês | MEDLINE | ID: mdl-34648226

RESUMO

Improving proton conductivity and fabricating viable metal-organic frameworks (MOFs) based proton exchange membranes (PEMs) are central issues exploiting electrolyte MOFs. We aim to design multivariate flexibility synergistic strategy to achieve Flexible MOFs (FMOFs) with high conductivity at a wide range of humidity. In situ powder X-ray diffraction (PXRD) and temperature-dependent Fourier transform infrared spectra (FT-IR) prove the synergistic self-adaption between dynamic torsion of alkyl sulfonic acid and dynamic breathing of FMOF, forming a continuous hydrogen-bonding networks to maintain high conductivity. Based on the convincing proton conductivity, we construct a series of long-term durable MOF-based PEMs that serve as a bridge between MOF and fuel cell. Consequently, the membrane electrode assembly (MEA) of the flexible PMNS1-40 exhibits a maximum single-cell power density of 34.76 mW cm-2 and hopefully opens doors to evaluate the practical application of proton-conducting MOFs in direct methanol fuel cells.

12.
J Hazard Mater ; 416: 125930, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492860

RESUMO

The pollution of heavy metals and organic compounds has received increased attention in recent years. In the current study, a novel biochar-based iron oxide composite (FeYBC) was successfully synthesized using pomelo peel and ferric chloride solution through one-step process at moderate temperature. Results clearly demonstrate that FeYBC exhibited more efficient removal of Cr(VI) and/or phenol compared with the pristine biochar, and the maximum adsorption amounts of Cr(VI) and phenol by FeYBC could reach 24.37 and 39.32 mg g-1, respectively. A series of characterization data suggests that several iron oxides such as Fe2O3, Fe0, FeOOH and Fe3O4 were formed on the FeYBC surface as well as oxygen-containing groups. Thermodynamics study indicates that Cr(VI) and phenol adsorption by FeYBC were endothermic and exothermic processes, respectively. Langmuir adsorption isotherm and pseudo-second order models could better explain the Cr(VI) and phenol adsorption behaviors over FeYBC. The Cr(VI) adsorption might be primarily achieved through the ion exchange and surface complexation and reduction, whereas the π-π interaction and electron donor-acceptor complex mainly contributed to phenol adsorption. The findings indicate that the biochar-based iron oxide composites material was an efficient adsorbent for the remediation of industrial effluents containing Cr(VI) and phenol.


Assuntos
Poluentes Químicos da Água , Água , Adsorção , Carvão Vegetal , Cromo , Compostos Férricos , Cinética , Fenol , Poluentes Químicos da Água/análise
13.
Huan Jing Ke Xue ; 42(10): 4826-4833, 2021 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-34581125

RESUMO

To explore the mechanism and efficiency of ammonia nitrogen removal, a pilot-scale biofilter for the simultaneous removal of high concentrations of iron, manganese, and ammonia nitrogen[Fe(Ⅱ) 11.9-14.8 mg·L-1, Mn(Ⅱ) 1.1-1.5mg·L-1, and NH4+-N 1.1-3.2 mg·L-1] from low temperature(5-6℃) groundwater was operated in a water supply plant in Northeast China. Results indicated excellent performance for ammonia nitrogen removal during the initial start-up stage. According to theoretical analysis and experimental verification, TNloss was driven by the adsorption of ammonia nitrogen by iron oxides, and the conversion of ammonia nitrogen into nitrate nitrogen occurred via biological nitrification. When the concentration of ammonia nitrogen increased, due to limited adsorption sites, the adsorption capacity of iron oxides remained stable at approximately 1 mg·L-1. For the same period, the amount of ammonia nitrogen removal via oxidation continued to increase, with higher quantities removed in the upper filter layer than in the lower filter layer. Dissolved oxygen(DO) is the limiting factor in the further increase in the removal of ammonia nitrogen by oxidation. With an increase in the filtration rate, the adsorption time of ammonia nitrogen by iron oxides was shortened, and the adsorption amount was reduced. Meanwhile, the shortening of EBCT reduced the ammonia nitrogen removed by nitrification under the action of nitrifying bacteria in the unit volume of the filter material. Based on these findings, it is recommended that the thickness of the filter layer should be increased to improve ammonia nitrogen removal performance.


Assuntos
Água Subterrânea , Purificação da Água , Amônia , Filtração , Nitrificação , Nitrogênio , Temperatura
14.
Ann Palliat Med ; 10(8): 8919-8929, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34488379

RESUMO

BACKGROUND: This study explored the effects of multi-component exercise training on the physical and cognitive function of the elderly with mild cognitive impairment (MCI). METHODS: A total of 90 older adults with MCI were chosen from screened volunteers and randomly assigned into 2 groups (n=45), and 84 completed the 6-month follow-up. Participants in the control group received general community health instruction, while the multi-component exercise training performed on the other group. The multi-component exercise training performed on these participants was designed to suit Chinese elderly based on advice from the nursing specialist and sports medicine specialist after the preliminary experiment. The Chinese version Mini-Physical Performance Test (CM-PPT), the Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment (MoCA) scores were examined by repeated measures analysis of variance to evaluate the physical and cognitive function of adults with MCI before and at 3 and 6 months after the intervention. The follow-up data collectors were blinded to group allocation. P<0.05 was considered statistically significant. RESULTS: (I) The average score of CM-PPT was increased from 11.36±2.69 to 11.88±2.40 and 12.83±2.19 in 3 and 6 months respectively after intervention, while control group was decreased from 10.79±2.73 to 10.24±2.62 in 3 months and 9.21±2.09 in 6 months. CM-PPT scores with the main intervention effect and the interaction between intervention and time were both statistically significant (P<0.05), indicating that the physical function of participants with MCI were improved after intervention. (II) The average score of MoCA was increased from 21.52±2.05 to 23.48±1.47 (3 months) and 25.19±1.29 (6 months) after intervention, while control group was decreased from 21.14.79±1.97 to 20.21±1.88 and 19.45±2.00 in 3 and 6 months. The score of MMSE showed the same trend with the score of MoCA. The MoCA score with main intervention effect and the MMSE and MoCA scores with the effect of time, the MMSE and MoCA scores with the interaction between the intervention and time were all statistically significant (P<0.05), showing that the cognitive function of participants with MCI was improved by the intervention. CONCLUSIONS: Multi-component exercise training could significantly improve physical function and cognitive function of the elderly with MCI. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100049350.


Assuntos
Disfunção Cognitiva , Idoso , Cognição , Disfunção Cognitiva/terapia , Exercício Físico , Humanos
15.
Autism ; : 13623613211041904, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34465247

RESUMO

LAY ABSTRACT: Autism spectrum disorder has long been conceptualized as a disorder of "atypical development of functional brain connectivity (which refers to correlations in activity levels of distant brain regions)." However, most of the research has focused on the connectivity between cortical regions, and much remains unknown about the developmental changes of functional connectivity between subcortical and cortical areas in autism spectrum disorder. We used the technique of resting-state functional magnetic resonance imaging to explore the developmental characteristics of intrinsic functional connectivity (functional brain connectivity when people are asked not to do anything) between subcortical and cortical regions in individuals with and without autism spectrum disorder aged 6-30 years. We focused on one important subcortical structure called striatum, which has roles in motor, cognitive, and affective processes. We found that cortico-striatal intrinsic functional connectivities showed opposite developmental trajectories in autism spectrum disorder and typically developing individuals, with connectivity increasing with age in autism spectrum disorder and decreasing or constant in typically developing individuals. We also found significant negative behavioral correlations between those atypical cortico-striatal intrinsic functional connectivities and autistic symptoms, such as social-communication deficits, and restricted/repetitive behaviors and interests. Taken together, this work highlights that the atypical development of cortico-subcortical functional connectivity might be largely involved in the neuropathological mechanisms of autism spectrum disorder.

17.
Aging (Albany NY) ; 13(17): 20896-20905, 2021 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-34495869

RESUMO

BACKGROUND: This study aimed to explore the significance of neutrophil-to-lymphocyte ratio (NLR), lactate dehydrogenase (LDH), D-dimer, and CT score in evaluating the severity and prognosis of coronavirus disease 2019 (COVID-19). METHODS: Patients with laboratory-confirmed COVID-19 were retrospectively enrolled. The baseline data, laboratory findings, chest computed tomography (CT) results evaluated by CT score on admission, and clinical outcomes were collected and compared. Logistic regression was used to assess the independent relationship between the baseline level of the four indicators (NLR, LDH, D-dimer, and CT score) and the severity of COVID-19. RESULTS: Among the 432 patients, 125 (28.94%) and 307 (71.06%) were placed in the severe and non-severe groups, respectively. As per the multivariate logistic regression, high levels of NLR and LDH were independent predictors of severe COVID-19 (OR=2.163; 95% CI=1.162-4.026; p=0.015 for NLR>3.82; OR=2.298; 95% CI=1.327-3.979; p=0.003 for LDH>246 U/L). Combined NLR>3.82 and LDH>246 U/L increased the sensitivity of diagnosis in patients with severe disease (NLR>3.82 [50.40%] vs. combined diagnosis [72.80%]; p=0.0007; LDH>246 [59.2%] vs. combined diagnosis [72.80%]; p<0.0001). CONCLUSIONS: High levels of serum NLR and LDH have potential value in the early identification of patients with severe COVID-19. Moreover, the combination of LDH and NLR can improve the sensitivity of diagnosis.


Assuntos
COVID-19/sangue , COVID-19/diagnóstico por imagem , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , L-Lactato Desidrogenase/sangue , Linfócitos/patologia , Neutrófilos/patologia , Tomografia Computadorizada por Raios X , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Prognóstico , Curva ROC
18.
Plants (Basel) ; 10(9)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34579323

RESUMO

Salt stress harms the growth and development of plants, and the degree of soil salinization in North China is becoming increasingly severe. Ectomycorrhiza (ECM) is a symbiotic system formed by fungi and plants that can improve the growth and salt tolerance of plants. No studies to date have examined the salt tolerance of Quercus mongolica, a typical ectomycorrhizal tree species of temperate forests in the northern hemisphere. Here, we inoculated Q. mongolica with two ectomycorrhizal fungi (Gomphidius viscidus; Suillus luteus) under NaCl stress to characterize the effects of ECM. The results showed that the symbiotic relationship of Q. mongolica with G. viscidus was more stable than that with S. luteus. The cross-sectional area of roots increased after inoculation with the two types of ectomycorrhizal fungi. Compared with the control group, plant height, soluble sugar content, and soluble protein content of leaves were 1.62, 2.41, and 2.04 times higher in the G. viscidus group, respectively. Chlorophyll (Chl) content, stomatal conductance (Gs), and intracellular CO2 concentration (Ci) were significantly higher in Q. mongolica inoculated with ectomycorrhizal fungi than in the control, but differences in the net photosynthetic rate (Pn), transpiration rate (Tr), and photosystem II maximum photochemical efficiency (Fv/Fm) were lower. The relative conductivity of Q. mongolica inoculated with the two ectomycorrhizal fungi was consistently lower than that of non-mycorrhizal seedlings, with the effect of G. viscidus more pronounced than that of S. luteus. The malondialdehyde (MDA) content showed a similar pattern. Peroxidase (POD) and catylase (CAT) levels in mycorrhizal seedlings were generally higher than those of non-mycorrhizal seedlings under normal conditions, and were significantly higher than those of non-mycorrhizal seedlings on the 36th and 48th day after salt treatment, respectively. Overall, the results indicated that the salt tolerance of Q. mongolica seedlings was improved by ectomycorrhizal inoculation.

19.
Chem Commun (Camb) ; 57(76): 9748-9751, 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34477187

RESUMO

Guanosine deaminase (GSDA) in plants specifically deaminates (de)guanosine to produce xanthosine with high specificity, which is further converted to xanthine, a key intermediate in purine metabolism and nitrogen recycling. We solved GSDA's structures from Arabidopsis thaliana in the free and ligand-bound forms at high resolutions. Unlike GDA, the enzyme employs a single-proton shuttle mechanism for catalysis and both the substrate and enzyme undergo structural rearrangements. The last fragment of the enzyme loops back and seals the active site, and the substrate rotates during the reaction, both essential to deamination. We further identified more substrates that could be employed by the enzyme and compare it with other deaminases to reveal the recognition differences of specific substrates. Our studies provide insight into this important enzyme involved in purine metabolism and will potentially aid in the development of deaminase-based gene-editing tools.


Assuntos
Arabidopsis/enzimologia , Nucleosídeo Desaminases/metabolismo , Biocatálise , Modelos Moleculares , Nucleosídeo Desaminases/química
20.
Acta Biomater ; 135: 705-722, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34469790

RESUMO

Additive manufacturing (AM) has enabled the fabrication of biodegradable porous metals to satisfy the desired characteristics for orthopedic applications. The geometrical design on AM biodegradable metallic scaffolds has been found to offer a favorable opportunity to regulate their mechanical and degradation performance in previous studies, however mostly confined to static responses. In this study, we presented the effect of the geometrical design on the dynamic responses of AM Mg scaffolds for the first time. Three different types of porous structures, based on various unit cells (i.e., biomimetic, diamond, and sheet-based gyroid), were established and then subjected to selective laser melting (SLM) process using group-developed Mg-Nd-Zn-Zr alloy (JDBM) powders. The topology after dynamic electropolishing, dynamic compressive properties, and dynamic biodegradation behavior of the AM Mg scaffolds were comprehensively evaluated. It was found that dynamic electropolishing effectively removed the excessive adhered powders on the surfaces and resulted in similar geometrical deviations amongst the AM Mg scaffolds, independent of their porous structures. The geometrical design significantly affected the compressive fatigue properties of the AM Mg scaffolds, of which the sheeted-based gyroid structure demonstrated a superior fatigue endurance limit of 0.85 at 106 cycles. Furthermore, in vitro dynamic immersion behaviors of the AM Mg scaffolds revealed a decent dependence on local architectures, where the sheeted-based gyroid scaffold experienced the lowest structural loss with a relatively uniform degradation mode. The obtained results indicate that the geometrical design could provide a promising strategy to develop desirable bone substitutes for the treatment of critical-size load-bearing defects. STATEMENT OF SIGNIFICANCE: Additive manufacturing (AM) has provided unprecedented opportunities to fabricate geometrically complex biodegradable scaffolds where the topological design becomes a key determinant on comprehensive performance. In this paper, we fabricate 3 AM biodegradable Mg scaffolds (i.e., biomimetic, diamond, and sheet-based gyroid) and report the effect of the geometrical design on the dynamic responses of AM Mg scaffolds for the first time. The results revealed that the sheeted-based gyroid scaffold exhibited the best combination of superior compressive fatigue properties and relatively uniform dynamic biodegradation mode, suggesting that the regulation of the porous structures could be an effective approach for the optimization of AM Mg scaffolds as to satisfy clinical requirements in orthopedic applications.


Assuntos
Materiais Biocompatíveis , Substitutos Ósseos , Metais , Porosidade , Tecidos Suporte , Suporte de Carga
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