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Applications of the type-I fiber Bragg gratings (FBGs) written through the coating (TTC) in strain sensing and tunable distributed Bragg reflector (DBR) fiber lasers were demonstrated. We reported the principle of selecting the distance between the fiber and the phase mask when writing type-I TTC FBGs. Type-I TTC FBGs written in commercially available acrylate-coated fibers with various geometries and their strain responses were demonstrated. Results showed that the strain sensitivity of FBGs increases as the core-diameter decreases, probably due to the waveguide effect. In addition, a continuously tunable DBR fiber laser based on TTC FBGs was achieved with a wavelength tuning range of 19.934 nm around 1080 nm, by applying a strain of 0-21265.8 µÉ to the laser resonant cavity. The wavelength tuning range was limited by the splice point between the gain fiber and the passive fiber for transmitting pump and signal lasers. When the pump power was 100 mW, the relative intensity noises were -97.334 dB/Hz at the relaxation oscillation peak of 880 kHz and -128 dB/Hz at frequencies greater than 3 MHz. The results open a potential scheme to design and implement continuously tunable fiber lasers and fiber laser sensors for strain sensing with a higher resolution.
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Potassium carbonate-catalyzed (3 + 2) cycloaddition reaction between N-2,2,2-trifluoroethylisatin ketimines and azodicarboxylates has been developed, constructing a series of novel N-heterocycle infused spirooxindoles in good to excellent yields (up to 98%) under milder conditions. The presence of both biologically active oxindole and trifluoromethyl-1,2,4-triazoline moieties in these novel spirocyclic compounds would provide new lead structures in the discovery of heterocyclic compounds with potential pharmaceutical activities.
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We demonstrate a single longitudinal mode distributed Bragg reflection (DBR) fiber laser by directly fabricating fiber Bragg gratings (FBGs) on an ytterbium-doped fiber (YDF) using a femtosecond laser. A simple optical self-injection feedback method was used to effectively compress the linewidth and reduce relative intensity noise (RIN) of a single longitudinal mode DBR fiber laser. Further, we investigated the effect of self-injection feedback cavity length and reflectivity on linewidth compression and determined that the linewidth tends to decrease with the increase of the external cavity photon lifetime. By a self-injection feedback, the laser linewidth was compressed from 31.8 kHz to 1.4 kHz. Meanwhile, the relaxation oscillation peak from -103.2d B/H z at 1.51 MHz was suppressed to -122.3d B/H z at 0.16 MHz. This low-noise narrow linewidth single longitudinal mode fiber laser is expected to be a promising candidate for applications such as active detection of neutral atmosphere and distributed fiber sensing.
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Six 8-oxoprotoberberines were synthesized collectively in four steps with acceptable yields (14-19%), of which the products 8-oxopalmatine, 8-oxopseudopalmatine, 8-oxoberberine, and 8-oxopseudoberberine come from nature. The synthetic route was featured with the In(OTf)3-catalyzed cyclization and Heck coupling. Moreover, the syntheses of the natural products berberine, canadine, and iambertine were achieved via various reductions from 8-oxoberberine, which provided a concise approach to the syntheses of this kind of alkaloids.
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This paper explores the relationship between normalized vegetation index (NDVI) response to precipitation and temperature conditions by analyzing the spatial and temporal variation of vegetation cover (NDVI) in Mu Us Desert during 2000-2019. MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Maximum Value Composites (MVC) is an internationally used statistical method for NDVI data. Based on MODIS remote sensing data, the NDVI of Mu Us Desert sandy land from 2000 to 2019 was analyzed by using the linear regression slope method. In 2000-2010 and 2010-2019, there was a difference in the change rate of vegetation index in Mu Us Desert, with the average slope of 0.0650/10a for the former and 0.0782/10a for the latter. The trends of NDVI values in the study area during 2000-2019 were roughly the same as those of precipitation, and slightly different from those of temperature, but the overall correlation between NDVI values and both was good. There is a significant positive correlation between NDVI and annual precipitation (0.687), and a weak correlation with temperature (0.264). The vegetation growth in Mu Us Desert is affected by both precipitation and temperature.
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Cambio Climático , Temperatura , Modelos Lineales , ChinaRESUMEN
MAIN CONCLUSION: N-decanoyl-homoserine lactone activates plant systemic resistance against Botrytis cinerea in tomato plants, which is largely dependent on jasmonic acid biosynthesis and signal transduction pathways. Rhizosphere bacteria secrete N-acylated-homoserine lactones (AHLs), a type of specialized quorum-sensing signal molecule, to coordinate their population density during communication with their eukaryotic hosts. AHLs behave as low molecular weight ligands that are sensed by plants and promote the host's resistance against foliar pathogens. In this study, we report on N-decanoyl-homoserine lactone (DHL), which is a type of AHL that induces systemic immunity in tomato plants and protects the host organism against the necrotrophic fungus Botrytis cinerea. Upon DHL treatment, tomato endogenous jasmonic acid (JA) biosynthesis (rather than salicylic acid biosynthesis) and signal transduction were significantly activated. Strikingly, the DHL-induced systemic resistance against B. cinerea was blocked in the tomato JA biosynthesis mutant spr2 and JA signaling gene-silenced plants. Our findings highlight the role of DHL in systemic resistance against economically important necrotrophic pathogens and suggest that DHL-induced immunity against B. cinerea is largely dependent on the JA signaling pathway. Manipulation of DHL-induced resistance is an attractive disease management strategy that could potentially be used to enhance disease resistance in diverse plant species.
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4-Butirolactona/análogos & derivados , Botrytis , Ciclopentanos/metabolismo , Resistencia a la Enfermedad/fisiología , Homoserina/análogos & derivados , Oxilipinas/metabolismo , Enfermedades de las Plantas/microbiología , Transducción de Señal , Solanum lycopersicum/microbiología , 4-Butirolactona/metabolismo , Arabidopsis , Botrytis/metabolismo , Silenciador del Gen , Homoserina/metabolismo , Solanum lycopersicum/fisiologíaRESUMEN
A unique gold(i)-catalyzed 5-endo-dig cyclization/aerobic oxidation cascade strategy from 1,5-enyne substrates with molecular oxygen as the oxidant to yield the indenone was described. The reaction mechanism was studied by heavy atom labelling and some related experiments. This method was applied to the formal total synthesis of isoprekinamycin.
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Increasing atmospheric CO2 concentrations ([CO2]) in agricultural and natural ecosystems is known to reduce plant stomatal opening, but it is unclear whether these CO2-induced stomatal alterations are associated with foliar pathogen infections. In this study, tomato plants were grown under ambient and elevated [CO2] and inoculated with Pseudomonas syringae pv. tomato strain DC3000, a strain that is virulent on tomato plants. We found that elevated [CO2] enhanced tomato defence against P. syringae. Scanning electron microscopy analysis revealed that stomatal aperture of elevated [CO2] plants was considerably smaller than their ambient counterparts, which affected the behaviour of P. syringae bacteria on the upper surface of epidermal peels. Pharmacological experiments revealed that nitric oxide (NO) played a role in elevated [CO2]-induced stomatal closure. Silencing key genes involved in NO generation and stomatal closing, nitrate reductase (NR) and guard cell slow-type anion channel 1 (SLAC1), blocked elevated [CO2]-induced stomatal closure and resulted in significant increases in P. syringae infection. However, the SLAC1-silenced plants, but not the NR-silenced plants, still had significantly higher defence under elevated [CO2] compared with plants treated with ambient [CO2]. Similar results were obtained when the stomata-limiting factor for P. syringae entry was excluded by syringe infiltration inoculation. These results indicate that elevated [CO2] induces defence against P. syringae in tomato plants, not only by reducing the stomata-mediated entry of P. syringae but also by invoking a stomata-independent pathway to counteract P. syringae. This information is valuable for designing proper strategies against bacterial pathogens under changing agricultural and natural ecosystems.
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Dióxido de Carbono/metabolismo , Enfermedades de las Plantas/microbiología , Estomas de Plantas/metabolismo , Pseudomonas syringae/fisiología , Solanum lycopersicum/metabolismo , Solanum lycopersicum/microbiología , Silenciador del Gen , Solanum lycopersicum/genética , Estomas de Plantas/microbiología , Plantones/metabolismo , Plantones/microbiologíaRESUMEN
Increasing CO2 concentrations ([CO2]) have the potential to disrupt plant-pathogen interactions in natural and agricultural ecosystems, but the research in this area has often produced conflicting results. Variations in phytohormone salicylic acid (SA) and jasmonic acid (JA) signalling could be associated with variations in the responses of pathogens to plants grown under elevated [CO2]. In this study, interactions between tomato plants and three pathogens with different infection strategies were compared. Elevated [CO2] generally favoured SA biosynthesis and signalling but repressed the JA pathway. The exposure of plants to elevated [CO2] revealed a lower incidence and severity of disease caused by tobacco mosaic virus (TMV) and by Pseudomonas syringae, whereas plant susceptibility to necrotrophic Botrytis cinerea increased. The elevated [CO2]-induced and basal resistance to TMV and P. syringae were completely abolished in plants in which the SA signalling pathway nonexpressor of pathogenesis-related genes 1 (NPR1) had been silenced or in transgenic plants defective in SA biosynthesis. In contrast, under both ambient and elevated [CO2], the susceptibility to B. cinerea highly increased in plants in which the JA signalling pathway proteinase inhibitors (PI) gene had been silenced or in a mutant affected in JA biosynthesis. However, plants affected in SA signalling remained less susceptible to this disease. These findings highlight the modulated antagonistic relationship between SA and JA that contributes to the variation in disease susceptibility under elevated [CO2]. This information will be critical for investigating how elevated CO2 may affect plant defence and the dynamics between plants and pathogens in both agricultural and natural ecosystems.
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Botrytis/fisiología , Dióxido de Carbono/farmacología , Enfermedades de las Plantas/inmunología , Reguladores del Crecimiento de las Plantas/metabolismo , Pseudomonas syringae/fisiología , Solanum lycopersicum/fisiología , Ciclopentanos/metabolismo , Susceptibilidad a Enfermedades , Regulación de la Expresión Génica de las Plantas , Interacciones Huésped-Patógeno , Solanum lycopersicum/genética , Solanum lycopersicum/inmunología , Modelos Teóricos , Oxilipinas/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/inmunología , Hojas de la Planta/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Ácido Salicílico/metabolismo , Transducción de SeñalRESUMEN
This study is a preliminary investigation exploring the mechanical properties of three-dimensional (3D)-printed personalized mesh titanium alloy prostheses and the feasibility of repairing hemi-mandibular defects. The ANSYS 14.0 software and selective laser melting (SLM) were used to produce personalized mesh titanium alloy scaffolds. Scaffolds printed using different parameters underwent fatigue property tests and scanning electron microscopy (SEM) of the fracture points. Models of hemi-mandibular defects (encompassing the temporomandibular joint) were created using beagle dogs. Freeze-dried allogeneic mandibles or 3D-printed personalized mesh titanium alloy prostheses were used for repair. Gross observation, computed tomography (CT), SEM, and histological examinations were used to compare the two repair methods. The prostheses with filament diameters of 0.5 and 0.7 mm could withstand 14,000 times and >600,000 cycles of alternating stresses, respectively. The truss-structure scaffold with a large aperture and large aperture ratio could withstand roughly 250,000 cycles of alternating forces. The allogeneic mandible graft required intraoperative shaping, while the 3D-printed mesh titanium alloy prostheses were personalized and did not require intraoperative shaping. The articular disc on the non-operated sides experienced degenerative changes. No liver and kidney toxicity was observed in the two groups of animals. The 3D-printed mesh titanium alloy prostheses could effectively restore the shape of the mandibular defect region and reconstruct the temporomandibular joint.
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Aleaciones , Impresión Tridimensional , Titanio , Animales , Perros , Titanio/química , Aleaciones/química , Mandíbula/cirugía , Ensayo de Materiales , Mallas Quirúrgicas , Prótesis e ImplantesRESUMEN
Helicobacter pylori (H. pylori) infection is considered to be an important factor in gastric cancer (GC). Long noncoding RNA (lncRNA) and m6A modification are involved in the occurrence and development of GC, but the role of lncRNA m6A modification in the development of GC mediated by H. pylori is still unclear. Here, we found that H. pylori infection downregulated the expression of lnc-PLCB1 through METTL14-mediated m6A modification and IRF2-mediated transcriptional regulation. Overexpression of lnc-PLCB1 inhibited the proliferation and migration of GC cells, while downregulation of lnc-PLCB1 promoted the proliferation and migration ability of GC cells. In addition, clinical analysis showed that lnc-PLCB1 is lower in GC tissues than in normal tissues. Further study found that lnc-PLCB1 reduced the protein stability of its binding protein DEAD-box helicase 21 (DDX21) and then downregulated the expression of CCND1 and Slug, thereby playing tumour suppressing role in the occurrence and development of GC. In conclusion, the METTL14/lnc-PLCB1/DDX21 axis plays an important role in H. pylori-mediated GC, and lnc-PLCB1 can be used as a new target for GC treatment.
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Adenina , Infecciones por Helicobacter , Helicobacter pylori , ARN Largo no Codificante , Neoplasias Gástricas , Humanos , Helicobacter pylori/metabolismo , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Neoplasias Gástricas/patología , Regulación hacia Abajo , Infecciones por Helicobacter/complicaciones , Infecciones por Helicobacter/genética , Proliferación Celular , ARN Helicasas DEAD-box/genética , ARN Helicasas DEAD-box/metabolismo , Fosfolipasa C beta/genética , Fosfolipasa C beta/metabolismo , Metiltransferasas/genética , Metiltransferasas/metabolismoRESUMEN
Agricultural production in the Weibei rainfed highland, Northwest China, is challenged by severe drought and water shortages. While the land use pattern has shifted gradually from crop production to orchard farming in Weibei, little is known about the influence of fruit industry development on regional water resources and the rationality of planting orchards. Here, we characterized soil water depletion patterns in rainfed orchards and farmlands to evaluate the occurrence of soil desiccation under land use conversion from farmlands to orchards in Weibei. Soil moisture dynamics were monitored in the 0-150 cm soil profiles of different aged Red Fuji apple orchards (young: 7 years, mature: 13 years, old: 22 years) and long-term cultivated winter wheat fields. We measured soil moisture content by oven-drying method in the middle of each month during the growing season of apple trees (March-September 2019). The over-depletion and depletion of soil water were analyzed to evaluate water stress and differential water depletion by distinct vegetation, respectively. The soil desiccation index was used to determine the occurrence of dry soil layers. Water stress was only observed at the 0-70-cm soil depths in the old orchards (mid-June) and farmlands (mid-May-mid-July). Water depletion took place at deeper depths for longer periods in the older orchards than in the younger orchards. Soil desiccation was absent in the young orchards, with mild desiccation at the 0-80-cm soil depths in the mature and old orchards in mid-June. The desiccation intensity was mild at the 0-60-cm soil depths in mid-April-mid-May, intense at the 0-150-cm soil depths in mid-June, and moderate at the 20-150-cm soil depths in mid-July. Results of this study demonstrate the mitigation of water stress and soil desiccation following conversion from wheat fields to apple orchards, which verifies the rationality of planting orchards in the rainfed highland area. Our findings provide strong support for developing a novel model of agro-industrial development, ecological construction, and sustainable economy in the vast arid and semi-arid areas of Northwest China.
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Malus , Suelo , Triticum , Deshidratación , Agricultura/métodosRESUMEN
Arable land is the lifeblood of food production, it is of great significance to promote the protection of arable land and ensure national food security by accurately understanding the change law of cultivated land and its driving mechanism. This study takes the Weibei dry plateau region of China as an example, explores its spatial and temporal change characteristics through the center of gravity shift and land use shift matrix, and couples the geographic probe model to reveal the driving mechanisms affecting arable land change. The results show that in the past 25 years, the total arable land area in the Weibei Dry Plateau Region of China has decreased by 5.58%, and the stability of arable land resources in the whole region has weakened. The center of gravity of arable land shifts to the northeast, and the standard deviation ellipse of arable land mainly undergoes the change process of "increase (1995-2015)-decrease (2015-2020)", and the spatial distribution of arable land tends to be dispersed. In the LISA frequency mapping, the proportion of stable constant and low-frequency areas is as high as 89.58%, and the spatial pattern of cultivated land is relatively stable. Medium and high frequency areas. The transformation mode is mainly "low-low" aggregation, "low-high" aggregation is not significant, and the decline of cultivated land in the study area is more obvious. In the past 25 years, a total of 1017.26 km2 of arable land was converted to construction land. The explanatory power of the influencing factors varies in each period (0.299 to 0.731), with total agricultural machinery power has the strongest explanatory power of 0.694, 0.592, and 0.731, respectively. The interaction between slope and annual average temperature and other factors being the highest, both greater than 0.8. Through the construction of LISA frequency mapping, combined with the center of gravity model and standard deviation ellipse, the spatial evolution trend of regional arable land is more comprehensively and dynamically grasped. By using the geodetector model, the driving mechanism of the changes of arable land is revealed comprehensively, which provides a theoretical basis for the scientific management and effective protection of arable land resources and a basis for decision-making.
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The rapid development of China's new urbanization has created favorable conditions for economic growth and social development. Urbanization includes population urbanization and land urbanization, among which land urbanization leads to land ecological security problems. At present, there is a lack of comprehensive understanding of land ecological security in China's new urbanization construction. This paper aims to fill the gap by systematically combing relevant literature on the connotation, status, and governance of land ecological security in China's new urbanization. Literature review shows that China's land ecological security is still at a low level, and the new urbanization construction has significant impacts on land ecological security. Land contamination is the most critical factor threatening land ecological security, and there are differences in the levels of land contamination and types of pollutants in different new urbanization construction forms. According to an example of land ecological security governance with enterprises as the main body and multiple subjects cooperating, the governance of land ecological security needs to integrate a variety of different subjects to coordinate governance. Future research directions should focus on the construction of land ecological security assessment index system, development of land contamination multi-level control technology, and construction of multi-subject collaborative governance model with "government-enterprise-social organization-residents."
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Ecosistema , Urbanización , Humanos , Cambio Social , Desarrollo Económico , ChinaRESUMEN
PURPOSE: To evaluate root-analog implants (RAIs) fabricated by selective laser melting (SLM). MATERIALS AND METHODS: Two types of implants (a maxillary right first molar RAI and a screw-cylinder-type molar implant) were designed using CAD software. Both implant types were fabricated with the SLM technique using Ti-6Al-4V powder. The stress distribution and micromotion of the implants were evaluated using finite element analysis, and the mechanical properties of the printed implants (relative density and compression test), surface properties of an SLM-fabricated specimen (morphology, roughness, and contact angle test), and biocompatibility of an SLM-fabricated specimen (osteoblast attachment, metal ion precipitation analysis, cell viability, and osteogenic gene expression) were evaluated. RESULTS: The RAI model exhibited better stress distribution and less micromotion than the screw-cylinder implant model. The screw-cylinder implant was better than the RAI at withstanding pressure, but both implant types could withstand masticatory forces. The densities of both implant types were similar to those of the bulk materials. Block samples made using the same SLM technique as the RAI exhibited good surface properties and excellent biocompatibility. CONCLUSION: The properties of the molar RAI fabricated with the SLM technique suggest that it may have potential for future clinical use, but this will need to be verified by in vivo studies.
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Implantes Dentales , Rayos Láser , Propiedades de Superficie , Análisis de Elementos Finitos , Tornillos ÓseosRESUMEN
Evapotranspiration (ET) plays a crucial role in hydrological and energy cycles, as well as in the assessments of water resources and irrigation demands. On a regional scale, particularly in the agro-pastoral ecotone, clarification of the distribution of surface ET and its influencing factors is critical for the rational use of water resources, restoration of the ecological environment, and protection of ecological water sources. The SEBAL model was used to invert the regional ET based on Landsat8 images in the agro-pastoral ecotone of northwest China. The results were indirectly verified by monitoring data from meteorological stations. The correlation between ET and surface parameters was analyzed. Thus, the main factors that affect the surface ET were identified. The results show that the SEBAL model determines an accurate inversion, with a correlation coefficient of 0.81 and an average root mean square error of 0.9 mm/d, which is highly suitable for research on water resources. The correlation coefficients of normalized vegetation index, surface temperature, land surface albedo, net radiation flux with daily ET were 0.5830, 0.8425, 0.3428 and 0.9111, respectively. The normalized vegetation index and the net radiation flux positively correlated with the daily ET, while the surface temperature and land surface albedo negatively correlated with the daily ET. The correlation from strong to weak is the net radiation flux > surface temperature > normalized vegetation index > surface albedo. In terms of spatial distribution, the daily ET of water was the highest, followed by woodland, wetland, cropland, built-up land, shrub land, grassland and bare land. However, the SEBAL model overestimates the inversion of daily ET of built-up land.
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Ecosistema , Bosques , China , Temperatura , AguaRESUMEN
In order to solve the soil problem of poor structure and low fertility after the abandoned homestead reclamation of Hollow Village in Loess Area and to improve the quality of the reclaimed soil in Hollow Village, a five-year field experiment was conducted here. In this experiment, the following seven treatments were applied: no modified material (CK), maturing agent (TM), fly ash (TF), organic fertilizer (TO), maturing agent + fly ash (TMF), maturing agent + organic fertilizer (TMO) and fly ash + organic fertilizer (TFO), and the effects of different improved materials on soil properties and crop yield were studied. The results showed that: soil organic matter (SOM) and total nitrogen contents increased significantly after the application of different improved materials, which promoted the cementation and aggregation of water-stable microaggregates (< 0.25 mm), and the water-stable macroaggregates showed an increasing trend. In the 0-0.15 m soil layer, the proportion of water-stable macroaggregates under TM, TF, TO, TMF, TMO, and TFO treatment increased by 328.2%, 130.0%, 87.8%, 81.1%, 36.7%, and 12.2% compared with CK, respectively. Meanwhile, TF, TO, TMF, TMO, TFO treatments significantly increased the mean weight diameter (MWD) and geometric mean diameter (GMD) values, reduced soil bulk density, the stable aggregate index (ELT) and fractal dimension (D) values (P < 0.05), and the stability of soil structure and the capacity of soil moisture retention has been significantly improved. The SOM content had a significant positive correlation with MWD, GMD, and > 2 mm water-stable aggregates and a significant negative correlation with the ELT, D, and water-stable microaggregates. In particular, the organic-inorganic coupling treatment of TFO showed the highest SOM content, soil moisture content, water-stable macroaggregates and maize yield, which was the most appropriate amendment for improving the reclaimed soil structure and fertility of Hollow Village in Loess Area.
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Fertilizantes , Suelo , Agricultura/métodos , China , Ceniza del Carbón , Nitrógeno , Suelo/química , Agua , Zea maysRESUMEN
Helicobacter pylori (H. pylori) is one of the main causes of gastric cancer. It has been reported that circRNAs play a vital role in the development of multiple types of cancer. However, the role of H. pylori-induced circRNAs in the development of gastric cancer has not been studied. In this study, we found that H. pylori could induce the upregulation of circMAN1A2 in AGS and BGC823 cells independent of CagA. The downregulation of circMAN1A2 could inhibit the proliferation, migration and invasion of gastric cancer cells, and circMAN1A2 could promote the progression of gastric cancer induced by H. pylori by sponging miR-1236-3p to regulate MTA2 expression. Furthermore, circMAN1A2 knockdown inhibited xenograft tumour growth in vivo, and the overexpression of circMAN1A2 was associated with the progression of gastric cancer. Hence, Helicobacter pylori induced circMAN1A2 expression to promote the carcinogenesis of gastric cancer, and circMAN1A2 might be a new potential diagnostic marker and therapeutic target for gastric cancer.
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Infecciones por Helicobacter , Helicobacter pylori , MicroARNs , Neoplasias Gástricas , Infecciones por Helicobacter/complicaciones , Infecciones por Helicobacter/genética , Infecciones por Helicobacter/metabolismo , Helicobacter pylori/metabolismo , Histona Desacetilasas/metabolismo , Humanos , MicroARNs/metabolismo , ARN Circular/genética , Proteínas Represoras/metabolismo , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismoRESUMEN
Herein, we report an unprecedented intramolecular cross-nucleophile coupling strategy of indole tethered ß-amino acrylates using a catalyst system combining λ3-iodanes and Lewis acids to achieve the chemodivergent synthesis of three unique alkaloid skeletons. It was worth noting that the acquisition of spiroindolenines and azepino[4,5-b]indoles derivatives was switchable with choice of the Lewis acids. Moreover, the polycyclic spiroindolines containing a lactone fragment could also be accessed for the first time via cross-nucleophile coupling cascade intramolecular condensation sequence.
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Acrilatos , Ácidos de Lewis , Catálisis , Ciclización , Alcaloides IndólicosRESUMEN
Tillage treatments have an important effect on soil microstructure characteristics, water thermal properties and nutrients, but little is known in the newly reclaimed cultivated land. For the reason, a long-term field study was to evaluate the tillage effects on soil physicochemical properties and crop yield in newly reclaimed cultivated land via the macroscopic and microscopic analysis. Three tillage treatments were tested: continuous conventional moldboard plow tillage (CT), sub-soiling/moldboard-tillage/sub-soiling tillage (ST) and no-tillage/sub-soiling/no-tillage (NT). Under CT, the microstructure was dominated by weakly separated plates structure and showed highest bulk density (BD) (1.49 g cm-3) and lowest soil organic matter (SOM) (3.68 g kg-1). In addition, CT reduced the capacity of soil moisture retention and temperature maintenance, resulting in aggregate structure deterioration and fragility. Unlike CT, the soil was characterized by moderately separated granular structure and highly separated aggregate structure under conservation tillage practice of ST and NT. NT was associated with the highest soil moisture content (20.42%), highest quantity of macroaggregates (> 0.25 mm) by wet-sieving (34.07%), and highest SOM (6.48 g kg-1) in the surface layer. Besides, NT was better able to regulate soil temperature and improved the values of geometric mean diameter. Under NT and ST, a stable soil structure with compound aggregates and pores was formed, and the maize yield was increased by 12.9% and 14.9% compared with CT, up to 8512.6 kg ha-1 and 8740.9 kg ha-1, respectively. These results demonstrated the positive effects of NT and ST on soil quality and crop yield in newly reclaimed cultivated land.