Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 152
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Plant Cell ; 35(8): 2848-2870, 2023 08 02.
Artículo en Inglés | MEDLINE | ID: mdl-37154077

RESUMEN

C3 and C4 grasses directly and indirectly provide the vast majority of calories to the human diet, yet our understanding of the molecular mechanisms driving photosynthetic productivity in grasses is largely unexplored. Ground meristem cells divide to form mesophyll or vascular initial cells early in leaf development in C3 and C4 grasses. Here we define a genetic circuit composed of SHORT ROOT (SHR), INDETERMINATE DOMAIN (IDD), and PIN-FORMED (PIN) family members that specifies vascular identify and ground cell proliferation in leaves of both C3 and C4 grasses. Ectopic expression and loss-of-function mutant studies of SHR paralogs in the C3 plant Oryza sativa (rice) and the C4 plant Setaria viridis (green millet) revealed the roles of these genes in both minor vein formation and ground cell differentiation. Genetic and in vitro studies further suggested that SHR regulates this process through its interactions with IDD12 and 13. We also revealed direct interactions of these IDD proteins with a putative regulatory element within the auxin transporter gene PIN5c. Collectively, these findings indicate that a SHR-IDD regulatory circuit mediates auxin transport by negatively regulating PIN expression to modulate minor vein patterning in the grasses.


Asunto(s)
Oryza , Setaria (Planta) , Humanos , Oryza/genética , Oryza/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Ácidos Indolacéticos/metabolismo , Setaria (Planta)/metabolismo , Diferenciación Celular , Regulación de la Expresión Génica de las Plantas/genética
2.
Clin Oral Implants Res ; 35(5): 573-584, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38467593

RESUMEN

OBJECTIVES: To introduce a modified guided bone regeneration (GBR) technique using intact periosteum and deproteinized bovine bone mineral (DBBM) for peri-implant augmentation and compare the clinical outcomes with those of conventional GBR. MATERIALS AND METHODS: Patients who received peri-implant augmentation in posterior sites between 2015 and 2021 were reviewed in this study. Group A was treated with a modified GBR technique, and Group B was treated with conventional GBR. For group comparison, propensity score matching was performed with a sensitivity analysis. The implant survival rate, dimensional changes in hard tissue, marginal bone loss (MBL), and peri-implant parameters were evaluated. RESULTS: In total, 114 implants from 98 patients were included. The implant survival rates were 95.74% in Group A and 95.00% in Group B during the follow-up period. At 6 months, the median horizontal thickness was recorded at 0.87 mm (IQ1-IQ3 = 0.00-1.75 mm) in Group A, exhibiting a relatively lower value compared to the corresponding measurement of 0.98 mm (IQ1-IQ3 = 0.00-1.89 mm) in Group B (p = .937). Vertical height displayed no statistically significant intergroup difference between the two groups (p = .758). The mean follow-up period was 25.83 ± 12.93 months after loading in Group A and 27.47 ± 21.29 months in Group B (p = .761). MBL and peri-implant parameters were comparable between the two groups. CONCLUSIONS: Within the limitations of this study, the modified GBR technique using intact periosteum and DBBM grafting might be a viable alternative to correct bone defects around implants in molar and premolar sites.


Asunto(s)
Regeneración Ósea , Regeneración Tisular Guiada Periodontal , Humanos , Estudios Retrospectivos , Femenino , Masculino , Persona de Mediana Edad , Estudios de Seguimiento , Adulto , Regeneración Tisular Guiada Periodontal/métodos , Implantación Dental Endoósea/métodos , Periostio/cirugía , Aumento de la Cresta Alveolar/métodos , Pérdida de Hueso Alveolar/cirugía , Resultado del Tratamiento , Anciano , Implantes Dentales
3.
Lipids Health Dis ; 23(1): 139, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38741154

RESUMEN

INTRODUCTION: Although previous studies have linked obesity and erectile dysfunction, the novel surrogate indicators of adipose accumulation are more essential and dependable factors to consider. Therefore, the primary objective of the current investigation was to examine and clarify the association between metabolic score for visceral fat (METS-VF) and erectile dysfunction. METHODS: Firstly, multivariate logistic regression analysis, smoothed curve fitting, and threshold effect analysis were employed to investigate the association between METS-VF and erectile dysfunction. Mediation analysis was also performed to evaluate the mediating role of homocysteine and inflammation. After that, subgroup analysis was carried out to examine the stability of the correlation of METS-VF with erectile dysfunction in various population settings. Furthermore, the area under the receiver operating characteristic (ROC) curve and eXtreme Gradient Boosting (XGBoost) algorithm were utilized to assess the capability of identifying METS-VF in comparison to the other four obesity-related indicators in identifying erectile dysfunction. RESULTS: After adjusting for all confounding factors, METS-VF was strongly and favourablely correlated with erectile dysfunction. With each additional unit rise in METS-VF, the prevalence of erectile dysfunction increased by 141%. A J-shaped relationship between METS-VF and erectile dysfunction was discovered through smoothed curve fitting. Marital status, physical activity, and smoking status can potentially modify this association. This finding of the ROC curve suggests that METS-VF had a powerful identifying capacity for erectile dysfunction (AUC = 0.7351). Homocysteine and inflammation mediated 4.24% and 2.81%, respectively. CONCLUSION: The findings of the current investigation suggest that METS-VF can be considered a dependable identifying indicator of erectile dysfunction.


Asunto(s)
Disfunción Eréctil , Curva ROC , Masculino , Disfunción Eréctil/metabolismo , Disfunción Eréctil/fisiopatología , Humanos , Persona de Mediana Edad , Grasa Intraabdominal/metabolismo , Grasa Intraabdominal/patología , Biomarcadores/metabolismo , Adulto , Homocisteína/sangre , Homocisteína/metabolismo , Obesidad/complicaciones , Obesidad/metabolismo , Anciano , Factores de Riesgo , Síndrome Metabólico/complicaciones , Síndrome Metabólico/metabolismo , Modelos Logísticos
4.
Int J Mol Sci ; 25(4)2024 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-38396834

RESUMEN

The periosteum is known as the thin connective tissue covering most bone surfaces. Its extrusive bone regeneration capacity was confirmed from the very first century-old studies. Recently, pluripotent stem cells in the periosteum with unique physiological properties were unveiled. Existing in dynamic contexts and regulated by complex molecular networks, periosteal stem cells emerge as having strong capabilities of proliferation and multipotential differentiation. Through continuous exploration of studies, we are now starting to acquire more insight into the great potential of the periosteum in bone formation and repair in situ or ectopically. It is undeniable that the periosteum is developing further into a more promising strategy to be harnessed in bone tissue regeneration. Here, we summarized the development and structure of the periosteum, cell markers, and the biological features of periosteal stem cells. Then, we reviewed their pivotal role in bone repair and the underlying molecular regulation. The understanding of periosteum-related cellular and molecular content will help enhance future research efforts and application transformation of the periosteum.


Asunto(s)
Regeneración Ósea , Periostio , Regeneración Ósea/fisiología , Osteogénesis/fisiología , Células Madre , Diferenciación Celular , Ingeniería de Tejidos
5.
Plant J ; 109(3): 523-540, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34750914

RESUMEN

The translocation of photosynthate carbohydrates, such as sucrose, is critical for plant growth and crop yield. Previous studies have revealed that sugar transporters, plasmodesmata and sieve plates act as important controllers in sucrose loading into and unloading from phloem in the vascular system. However, other pivotal steps for the regulation of sucrose movement remain largely elusive. In this study, characterization of two starch excesses in mesophyll (sem) mutants and dye and sucrose export assays were performed to provide insights into the regulatory networks that drive source-sink relations in rice. Map-based cloning identified two allelic mutations in a gene encoding a GLUCAN SYNTHASE-LIKE (GSL) protein, thus indicating a role for SEM1 in callose biosynthesis. Subcellular localization in rice showed that SEM1 localized to the plasma membrane. In situ expression analysis and GUS staining showed that SEM1 was mainly expressed in vascular phloem cells. Reduced sucrose transport was found in the sem1-1/1-2 mutant, which led to excessive starch accumulation in source leaves and inhibited photosynthesis. Paraffin section and transmission electron microscopy experiments revealed that less-developed vascular cells (VCs) in sem1-1/1-2 potentially disturbed sugar movement. Moreover, dye and sugar trafficking experiments revealed that aberrant VC development was the main reason for the pleiotropic phenotype of sem1-1/1-2. In total, efficient sucrose loading into the phloem benefits from an optional number of VCs with a large vacuole that could act as a buffer holding tank for sucrose passing from the vascular bundle sheath.


Asunto(s)
Transporte Biológico/genética , Células del Mesófilo/metabolismo , Oryza/genética , Oryza/fisiología , Floema/metabolismo , Almidón/genética , Almidón/metabolismo , Azúcares/metabolismo , Transporte Biológico/fisiología , Productos Agrícolas/genética , Productos Agrícolas/fisiología , Regulación de la Expresión Génica de las Plantas , Genes de Plantas
6.
Opt Express ; 31(26): 42850-42865, 2023 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-38178394

RESUMEN

The co-route optical fibers, comprising both co-cable and co-trench fibers, pose a significant potential risk to network service quality assurance by operators. They are incapable of achieving high-precision recognition and visual state management. In this study, we gathered both static and dynamic optical fiber data using a linewidth tunable light source (LTLS) and introduced a multimodal detection architecture that applies ensemble learning to the collected data. This constitutes what we believe to be the first field trial of concurrent recognition of optical fibers found both in co-cables and co-trenches. To identify co-cable fibers, we employed a double-layer cascaded Random Forest (DLC-RF) model based on the static features of fibers. For co-trench fiber, the dynamic characteristics of fiber vibrations are utilized in combination with multiple independent curve similarity contrast learners for classifying tasks. The proposed architecture is capable of automatically detecting the condition of the optical fiber and actively identifying the same routing segment within the network, eliminating the need for human intervention and enabling the visualization of passive optical fiber resources. Finally, after rigorous testing and validation across 11 sites in a typical urban area, including aggregation and backbone scenarios within the operator's live network environments, we have confirmed that the solution's ability to identify co-routes is accurate, exceeding 95%. This provides strong empirical evidence of its effectiveness.

7.
Chemistry ; 29(47): e202301214, 2023 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-37269539

RESUMEN

NiOx-based inverted perovskite solar cells (PSCs) have attracted growing attention due to their low cost and large-scale application potential. However, the efficiency and stability of inverted planar heterojunction PSCs is still unsatisfactory owing to insufficient charge-extraction caused by undesirable interfacial contact between perovskite and NiOx hole transport layers (HTLs). Herein an interfacial passivation strategy with guanidinium salts (guanidinium thiocyanate (GuASCN), guanidine hydrobromide (GuABr), guanidine hydriodate (GuAI)) as passivator is employed to solve this problem. We systematically study the effect of various guanidinium salts on the crystallinity, morphology, and photophysical properties of perovskite films. Guanidine salt as interfacial passivator can decrease interface resistance, reduce carrier non-radiative recombination, and boost carrier extraction. Notably, the GuABr-treated unencapsulated devices can still maintain more than 90 % of their initial PCE after aging for 1600 h at 16-25 °C and 35 %-50 % relative humidity in ambient conditions. This work reveals the significance of counterions in improving the photovoltaic performance and stability of PSCs.

8.
J Org Chem ; 88(15): 10753-10760, 2023 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-37467194

RESUMEN

A tetramethylammonium iodide (TBAI)-mediated cyclization and methylsulfonylation of propargylic amides enabled by dimethyl sulfite as a SO2 surrogate and methyl source have been developed. The transition metal-free and oxidant-free reaction provides a practical and efficient approach for the selective synthesis of methylsulfonyl oxazoles in moderate to excellent yields with good functional group compatibility.

9.
Biotechnol Lett ; 45(4): 521-536, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36790735

RESUMEN

PURPOSE: Pichia pastoris is well known for its ability to produce short and low-immunogenic humanized glycosyl chains onto recombinant glycoproteins, it was thus speculated to be applicable to synthesize oligosaccharides. In this study, generally recognized as safe (GRAS) microorganism Pichia pastoris GS115 was tested for its potential to be used as a new synthetic chassis to produce the most abundant human milk oligosaccharide 2'-fucosyllactose (2'-FL). METHODS: To enable the de novo synthesis of 2'-FL, lactose transporter lac12, two enzymes of gmd, gmer, and fucosyltransferases futC were integrated into the genome of P. pastoris, under the control of constitutive PGAP promoter. RESULTS: The resulting recombinant yeasts yielded up to 0.276 g/L through culture optimization in a 5 L bioreactor. CONCLUSION: To our knowledge, this is the first report of 2'-FL production in engineered Pichia pastoris. This work is a good starting point to produce 2'-FL using Pichia pastoris as a viable chassis.


Asunto(s)
Saccharomycetales , Trisacáridos , Humanos , Trisacáridos/genética , Oligosacáridos , Pichia/genética
10.
Angew Chem Int Ed Engl ; 62(40): e202309732, 2023 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-37580313

RESUMEN

Heteroatom doping has emerged as a highly effective strategy to enhance the activity of metal-based electrocatalysts toward the oxygen evolution reaction (OER). It is widely accepted that the doping does not switch the OER mechanism from the adsorbate evolution mechanism (AEM) to the lattice-oxygen-mediated mechanism (LOM), and the enhanced activity is attributed to the optimized binding energies toward oxygen intermediates. However, this seems inconsistent with the fact that the overpotential of doped OER electrocatalysts (<300 mV) is considerably smaller than the limit of AEM (>370 mV). To determine the origin of this inconsistency, we select phosphorus (P)-doped nickel-iron mixed oxides as the model electrocatalysts and observe that the doping enhances the covalency of the metal-oxygen bonds to drive the OER pathway transition from the AEM to the LOM, thereby breaking the adsorption linear relation between *OH and *OOH in the AEM. Consequently, the obtained P-doped oxides display a small overpotential of 237 mV at 10 mA cm-2 . Beyond P, the similar pathway transition is also observed on the sulfur doping. These findings offer new insights into the substantially enhanced OER activity originating from heteroatom doping.

11.
Anal Chem ; 94(33): 11514-11520, 2022 08 23.
Artículo en Inglés | MEDLINE | ID: mdl-35959591

RESUMEN

By virtue of the fascinating merits of low cost, rapid screening, and on-site detection, fluorescence lateral flow assays (FLFAs) have attracted considerable attention. Their detection limits are closely associated with the label probes used. The development of high-performance and robust phosphors remains a great challenge. Herein, we presented a new label probe, i.e., fluorescent carbon nanobeads (FCNBs), for FLFAs. Monodispersive, water-soluble, and highly emissive FCNBs were facilely prepared via a hydrothermal carbonization manner. Their abundant amino groups were beneficial for versatile surface functionalization. After being modified by biomolecules, the fabricated FCNB reporter probes were adopted for the construction of lateral flow test strips toward representative foodborne toxins, i.e., aflatoxin B1 (AFB1), and pathogenic bacteria, i.e., Staphylococcus aureus (S. aureus), respectively. The detection limits (0.01 ng/mL for AFB1 and 102 cfu/mL for S. aureus) were about 1 or 2 orders of magnitude lower than most reported methods. Furthermore, the proposed test strips were successfully applied for the quantitative, accurate, and rapid screening of AFB1 and S. aureus in food samples. This work provided a promising label probe for FLFAs and would open the opportunity to exploit a sensing platform by modifying different ligands onto the FCNBs.


Asunto(s)
Técnicas Biosensibles , Colorantes Fluorescentes , Aflatoxina B1/análisis , Técnicas Biosensibles/métodos , Carbono , Fluorescencia , Límite de Detección , Staphylococcus aureus
12.
Small ; 18(47): e2204148, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36220344

RESUMEN

In this work, the oxidation state of Sn and Cu active sites for CO2 electroreduction via constructing a Sn-Cun bimetallic oxide composite with a nanotube structure (SnCu-CNS) is successfully modulated. Compared to a single SnO2 or CuOx component, the SnCu-CNS composite holds reinforced electronegativity to generate unique extra Snδ+ centers and higher CuO centers with enhanced oxidation effect. Based on density functional theory calculations, the enlarged energy difference between Snδ+ /CuO centers and the reactants accelerates the electron transfer and decreases the energy barrier for the key intermediates to gain higher formate selectivity. Furthermore, the hollow structure and abundant micropores of SnCu-CNS are also conducive to the reactant transport and availability of active sites during CO2 electroreduction. In a conventional H-type cell, SnCu-CNS catalyst exhibits a maximum 95.1% faradaic efficiency for formate production. Switching to a flow cell configuration, SnCu-CNS can further deliver partial current densities exceeding 200 mA cm-2 and over 90% faradaic efficiencies for the formate, superior to most of the reported Sn-based electrocatalysts. This strategy of electronic modulation and morphology engineering in bimetallic oxides can have wide applications to raise electrocatalytic performance.

13.
Small ; 18(45): e2204446, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36166716

RESUMEN

Combining two kinds of electron transport layer (ETL) which have complementary advantages into a bilayer structure to form a bilayer ETL is an effective way to transcend inherent limitations of single-layer ETL, which is very helpful in the development of perovskite solar cells (PSCs). In this work, a strategy is proposed to break constraints on the application of the staggered bilayer ETL in high-efficiency PSC, namely utilizing a built-in field to overcome the dilemma in ECBM making it possible to improve VOC and FF simultaneously by tuning the Fermi level of ETLs properly. According to the strategy, a bilayer ETL structure comprised of C-TiO2 and SnO2 layer and corresponding Li-doping process are developed, and the characterization results confirm the effectiveness of the strategy, making the potentials of the C-TiO2 (Li)/SnO2 bilayer ETL fully released for its application in high-efficiency PSCs: a VOC of 1.201 V for an ordinary triple-cation-perovskite-based PSC and a photoelectric conversion efficiency of 24.3% for a low-bandgap-perovskite-based PSC with high haze FTO superstrate are successfully achieved, indicating that the C-TiO2 (Li)/SnO2 bilayer ETL is a successful application paradigm of the proposed strategy and very promising in the application of high-efficiency PSCs.

14.
Chemistry ; 28(14): e202104174, 2022 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-35083795

RESUMEN

Carbon dots (CDs) have recently emerged as antibacterial agents and have attracted considerable attention owing to their fascinating merits of small size, facile fabrication, and surface functionalization. Most of them are involved in external light activation or hybridization with other functional nanomaterials. Herein, we present peroxidase-like Cu-doped CDs (Cu-CDs) for in vitro antibacterial applications. The unique peroxidase-mimicking property of the Cu-CDs was demonstrated by tetramethylbenzidine chromogenic assay, electron paramagnetic resonance spectra, and hydroxy radical probe. Escherichia coli and Staphylococcus aureus were chosen as representative gram-negative/positive models against which Cu-CDs exhibited superior antimicrobial activity even at a dosage down to 5 µg/mL. A possible mechanism of action was that the Cu-CDs triggered a catalytic redox reaction of endogenous H2 O2 and glutathione depletion in the bacteria cells, with subsequent oxidative stress and membrane disruption. This work provides a new strategy for the design of microenvironment-responsive antimicrobial nano-agents.


Asunto(s)
Carbono , Puntos Cuánticos , Antibacterianos/farmacología , Cobre/farmacología , Estrés Oxidativo , Peroxidasa , Peroxidasas
15.
BMC Musculoskelet Disord ; 23(1): 1104, 2022 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-36529717

RESUMEN

OBJECTIVE: To evaluate the early clinical effect of oblique lumbar interbody fusion with lateral screw fixation and percutaneous endoscopic transforaminal discectomy (OLIF-PETD) in the treatment of lumbar disc herniation with lumbar instability. METHODS: A total of 22 patients with lumbar disc herniation and lumbar instability from August 2017 to August 2019 were enrolled in this retrospective study. The general information, perioperative indicators and complications were recorded. The clinical outcomes and radiological outcomes were evaluated before the operation, seven days after the operation, and at the last follow-up. Vertebral fusion and degree of multifidus muscle injury were evaluated at the last follow-up. RESULTS: In this study, OLIF + PETD showed shorter incision length compared to the MIS-TLIF (P < 0.001). In the two groups, the clinical outcomes and radiological outcomes were significantly improved compared with the preoperative (P < 0.001). At the seven days after the operation and the last follow-up, the VAS of OLIF + PETD group was lower than that of MIS-TLIF group (P < 0.05). OLIF + PETD could give superior outcome in restoring disc height (P < 0.001), but the fusion segment angle of OLIF + PETD group was larger compared to the MIS-TLIF group seven days after the operation and at the last follow-up (P < 0.05). In addition, the fusion rate was not significantly different between the two groups (P > 0.05), but OLIF + PETD could avoid the multifidus injury (P < 0.001). CONCLUSION: Compared to MIS-TLIF, OLIF-PETD can achieve satisfactory decompression effects and fusion rates with less multifidus injury and postoperative low back pain, which may be an alternative choice for the treatment of lumbar disc herniation combined with lumbar instability.


Asunto(s)
Discectomía Percutánea , Desplazamiento del Disco Intervertebral , Fusión Vertebral , Humanos , Desplazamiento del Disco Intervertebral/complicaciones , Desplazamiento del Disco Intervertebral/diagnóstico por imagen , Desplazamiento del Disco Intervertebral/cirugía , Vértebras Lumbares/diagnóstico por imagen , Vértebras Lumbares/cirugía , Estudios Retrospectivos , Procedimientos Quirúrgicos Mínimamente Invasivos , Resultado del Tratamiento , Tornillos Óseos
16.
Int J Mol Sci ; 23(9)2022 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-35563299

RESUMEN

Phospholipase Dα (PLDα), which produces signaling molecules phosphatidic acid (PA), has been shown to play a critical role in plants adapting to salt environments. However, it is unclear whether phospholipase Dδ (PLDδ) can mediate the salt response in higher plants. PePLDδ was isolated from salt-resistant Populus euphratica and transferred to Arabidopsis thaliana to testify the salt tolerance of transgenic plants. The NaCl treatment (130 mM) reduced the root growth and whole-plant fresh weight of wild-type (WT) A. thaliana, vector controls (VC) and PePLDδ-overexpressed lines, although a less pronounced effect was observed in transgenic plants. Under salt treatment, PePLDδ-transgenic Arabidopsis exhibited lower electrolyte leakage, malondialdehyde content and H2O2 levels than WT and VC, resulting from the activated antioxidant enzymes and upregulated transcripts of genes encoding superoxide dismutase, ascorbic acid peroxidase and peroxidase. In addition, PePLDδ-overexpressed plants increased the transcription of genes encoding the plasma membrane Na+/H+ antiporter (AtSOS1) and H+-ATPase (AtAHA2), which enabled transgenic plants to proceed with Na+ extrusion and reduce K+ loss under salinity. The capacity to regulate reactive oxygen species (ROS) and K+/Na+ homeostasis was associated with the abundance of specific PA species in plants overexpressing PePLDδ. PePLDδ-transgenic plants retained a typically higher abundance of PA species, 34:2 (16:0-18:2), 34:3 (16:0-18:3), 36:4 (18:2-18:2), 36:5 (18:2-18:3) and 36:6 (18:3-18:3), under control and saline conditions. It is noteworthy that PA species 34:2 (16:0-18:2), 34:3 (16:0-18:3), 36:4 (18:2-18:2) and 36:5 (18:2-18:3) markedly increased in response to NaCl in transgenic plants. In conclusion, we suppose that PePLDδ-derived PA enhanced the salinity tolerance by regulating ROS and K+/Na+ homeostasis in Arabidopsis.


Asunto(s)
Arabidopsis , Populus , Arabidopsis/metabolismo , Regulación de la Expresión Génica de las Plantas , Homeostasis , Peróxido de Hidrógeno/metabolismo , Peroxidasas/metabolismo , Fosfolipasas/metabolismo , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente/genética , Populus/genética , Populus/metabolismo , ATPasas de Translocación de Protón/genética , Especies Reactivas de Oxígeno/metabolismo , Tolerancia a la Sal/genética , Sodio/metabolismo , Cloruro de Sodio/metabolismo
17.
Angew Chem Int Ed Engl ; 61(15): e202115983, 2022 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-35099846

RESUMEN

A robust and highly active homogeneous chiral nickel-phosphine complex for the asymmetric hydrogenation of aliphatic γ- and δ-ketoacids has been discovered. The hydrogenation could proceed smoothly in the presence of 0.0133 mol% catalyst loading (S/C=7500). The coordination chemistry and catalytic behavior of Ni(OTf)2 with (S,S)-Ph-BPE were explored by 1 H NMR and HRMS. The mechanistic studies revealed that a proton promoted the activation of the substrate C=O bond and controlled the stereoselectivity through hydrogen bonds. A series of chiral γ- and δ-alkyl substituted lactones were obtained in high yields with excellent enantioselectivities (up to 98 % yield and 99 % ee). In addition, this catalytic system also demonstrated that levulinic acid produced from a biomass feedstock was converted into chiral γ-valerolactone without loss of ee value.

18.
Metab Eng ; 67: 330-346, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34329707

RESUMEN

The regulation of single gene transcription level in the metabolic pathway is often failed to significantly improve the titer of the target product, and even leads to the imbalance of carbon/nitrogen metabolic network and cofactor network. Global transcription machinery engineering (gTME) can activate or inhibit the synergistic expression of multiple genes in specific metabolic pathways, so transcription factors with specific functions can be expressed according to different metabolic regulation requirements, thus effectively increasing the synthesis of target metabolites. In addition, maintaining intracellular redox balance through cofactor engineering can realize the self-balance of cofactors and promote the efficient synthesis of target products. In this study, we rebalanced the central carbon/nitrogen metabolism and redox metabolism of Corynebacterium glutamicum S9114 by gTME and redox cofactors engineering to promote the production of the nutraceutical N-acetylglucosamine (GlcNAc). Firstly, it was found that the overexpression of the transcription factor RamA can promote GlcNAc synthesis, and the titer was further improved to 16 g/L in shake flask by using a mutant RamA (RamAM). Secondly, a CRISPR interference (CRISPRi) system based on dCpf1 was developed and used to inhibit the expression of global negative transcriptional regulators of GlcNAc synthesis, which promoted the GlcNAc titer to 27.5 g/L. Thirdly, the cofactor specificity of the key enzymes in GlcNAc synthesis pathway was changed by rational protein engineering, and the titer of GlcNAc in shake flask was increased to 36.9 g/L. Finally, the production of GlcNAc was scaled up in a 50-L fermentor, and the titer reached 117.1 ± 1.9 g/L, which was 6.62 times that of the control group (17.7 ± 0.4 g/L), and the yield was increased from 0.19 g/g to 0.31 g/g glucose. The results obtained here highlight the importance of engineering the global regulation of central carbon/nitrogen metabolism and redox metabolism to improve the production performance of microbial cell factories.


Asunto(s)
Acetilglucosamina , Bacillus subtilis , Bacillus subtilis/genética , Ingeniería Metabólica , Oxidación-Reducción , Factores de Transcripción/genética
19.
J Org Chem ; 86(23): 17496-17503, 2021 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-34747609

RESUMEN

A novel and efficient method for the synthesis of methyl sulfone derivatives via palladium-catalyzed methylsulfonylation of alkyl halides with dimethyl sulfite has been described. A variety of aryl and alkyl iodides underwent the sulfonylation smoothly to furnish methyl sulfites in moderate to excellent yields.

20.
Int J Mol Sci ; 22(21)2021 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-34769083

RESUMEN

Cadmium (Cd2+) pollution occurring in salt-affected soils has become an increasing environmental concern in the world. Fast-growing poplars have been widely utilized for phytoremediation of soil contaminating heavy metals (HMs). However, the woody Cd2+-hyperaccumulator, Populus × canescens, is relatively salt-sensitive and therefore cannot be directly used to remediate HMs from salt-affected soils. The aim of the present study was to testify whether colonization of P. × canescens with ectomycorrhizal (EM) fungi, a strategy known to enhance salt tolerance, provides an opportunity for affordable remediation of Cd2+-polluted saline soils. Ectomycorrhization with Paxillus involutus strains facilitated Cd2+ enrichment in P. × canescens upon CdCl2 exposures (50 µM, 30 min to 24 h). The fungus-stimulated Cd2+ in roots was significantly restricted by inhibitors of plasmalemma H+-ATPases and Ca2+-permeable channels (CaPCs), but stimulated by an activator of plasmalemma H+-ATPases. NaCl (100 mM) lowered the transient and steady-state Cd2+ influx in roots and fungal mycelia. Noteworthy, P. involutus colonization partly reverted the salt suppression of Cd2+ uptake in poplar roots. EM fungus colonization upregulated transcription of plasmalemma H+-ATPases (PcHA4, 8, 11) and annexins (PcANN1, 2, 4), which might mediate Cd2+ conductance through CaPCs. EM roots retained relatively highly expressed PcHAs and PcANNs, thus facilitating Cd2+ enrichment under co-occurring stress of cadmium and salinity. We conclude that ectomycorrhization of woody hyperaccumulator species such as poplar could improve phytoremediation of Cd2+ in salt-affected areas.


Asunto(s)
Basidiomycota/fisiología , Cadmio/metabolismo , Micorrizas/fisiología , Populus/fisiología , Sales (Química)/metabolismo , Biodegradación Ambiental , Salinidad , Cloruro de Sodio/metabolismo , Contaminantes del Suelo/metabolismo , Madera/fisiología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA