RESUMEN
Catalytic reduction of nitrate over bimetallic catalysts has emerged as a technology for sustainable treatment of nitrate-containing groundwater. However, the structure of bimetallic has been much less investigated for catalyst optimization. Herein, two main types of Pd-Cu bimetallic nanocrystal structures, heterostructure and intermetallic, were prepared and characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that two individual Pd and Cu nanocrystals with a mixed interface exist in the heterostructure nanocrystals, while Pd and Cu atoms are uniformly distributed across the intermetallic Pd-Cu nanocrystals. The catalytic nitrate reduction experiments were carried out in a semibatch reactor under constant hydrogen flow. The nitrate conversion rate of the heterostructure Pd-Cu nanocrystals supported on α-Al2O3, γ-Al2O3, SBA-15, and XC-72R exhibited 3.82-, 6.76-, 4.28-, 2.44-fold enhancements relative to the intermetallic nanocrystals, and the nitrogen and nitrite were the main products for the heterostructure and intermetallic Pd-Cu nanocrystals, respectively. This indicates that the catalytic nitrate reduction over Pd-Cu catalyst is sensitive to the bimetallic structures of the catalysts, and heterostructure bimetallic nanocrystals exhibit better catalytic performances on both the activity and selectivity, which may provide new insights into the design and optimization of catalysts to improve catalytic activity and selectivity for nitrate reduction in water.
Asunto(s)
Cobre , Nitratos , Oxidación-Reducción , Paladio , Catálisis , Cobre/química , Paladio/química , Nitratos/química , Nanopartículas del Metal/química , Nanopartículas/química , Contaminantes Químicos del Agua/química , Modelos QuímicosRESUMEN
Electrocatalytic reduction of nitrate to ammonia has been considered a promising and sustainable pathway for pollutant treatment and ammonia has significant potential as a clean energy. Therefore, the method has received much attention. In this work, Cu/Fe 2D bimetallic metal-organic frameworks were synthesized by a facile method applied as cathode materials without high-temperature carbonization. Bimetallic centers (Cu, Fe) with enhanced intrinsic activity demonstrated higher removal efficiency. Meanwhile, the 2D nanosheet reduced the mass transfer barrier between the catalyst and nitrate and increased the reaction kinetics. Therefore, the catalysts with a 2D structure showed much better removal efficiency than other structures (3D MOFs and Bulk MOFs). Under optimal conditions, Cu/Fe-2D MOF exhibited high nitrate removal efficiency (87.8%) and ammonium selectivity (89.3%) simultaneously. The ammonium yielded up to significantly 907.2 µg/(hr·mgcat) (7793.8 µg/(hr·mgmetal)) with Faradaic efficiency of 62.8% at an initial 100 mg N/L. The catalyst was proved to have good stability and was recycled 15 times with excellent effect. DFT simulations confirm the reduced Gibbs free energy of Cu/Fe-2D MOF. This study demonstrates the promising application of Cu/Fe-2D MOF in nitrate reduction to ammonia and provides new insights for the design of efficient electrode materials.
Asunto(s)
Amoníaco , Cobre , Hierro , Estructuras Metalorgánicas , Nitratos , Contaminantes Químicos del Agua , Amoníaco/química , Cobre/química , Nitratos/química , Estructuras Metalorgánicas/química , Hierro/química , Contaminantes Químicos del Agua/química , Catálisis , Modelos Químicos , Oxidación-Reducción , CinéticaRESUMEN
Nitrate (NO3-) is a widespread pollutant in high-salt wastewater and causes serious harm to human health. Although electrochemical removal of nitrate has been demonstrated to be a promising treatment method, the development of low-cost electro-catalysts is still challenging. In this work, a phosphate modified iron (P-Fe) cathode was prepared for electrochemical removal of nitrate in high-salt wastewater. The phosphate modification greatly improved the activity of iron, and the removal rate of nitrate on P-Fe was three times higher than that on Fe electrode. Further experiments and density functional theory (DFT) calculations demonstrated that the modification of phosphoric acid improved the stability and the activity of the zero-valent iron electrode effectively for NO3- removal. The nitrate was firstly electrochemically reduced to ammonium, and then reacted with the anodic generated hypochlorite to N2. In this study, a strategy was developed to improve the activity and stability of metal electrode for NO3- removal, which opened up a new field for the efficient reduction of NO3- removal by metal electrode materials.
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Electrodos , Hierro , Nitratos , Fosfatos , Eliminación de Residuos Líquidos , Aguas Residuales , Contaminantes Químicos del Agua , Aguas Residuales/química , Nitratos/química , Hierro/química , Fosfatos/química , Contaminantes Químicos del Agua/química , Eliminación de Residuos Líquidos/métodos , Técnicas Electroquímicas/métodosRESUMEN
The Guanabara Bay hydrographic region (GBHR) has served as a central hub for human settlement and resource utilization throughout Brazil's history. However, the region's high population density and intense industrial activity have come at a cost, leading to a significant decline in water quality. This work aimed to identify homogeneous regions in GBHR according to water quality parameters in dry and rainy periods. The following water quality monitoring variables were monitored at 49 gauge stations: total phosphorus (TP), nitrate (NO3-), dissolved oxygen (DO), hydrogenionic potential (pH), turbidity (Turb), thermotolerant coliforms (TCol), total dissolved solids (TDS), biochemical oxygen demand (BOD), water temperature (Tw), and air temperature (Ta). The statistical analysis consisted of determining principal components, cluster analysis, seasonal differences, and Spearman's correlation. The water quality parameter correlations were not expressively influenced by seasonality, but there are differences in the concentrations of these parameters in the dry and rainy periods. In the dry period, urban pressure on water quality is mainly due to fecal coliforms. The resulting clusters delimited areas under urban, agricultural, and forestry influence. Clusters located in areas with high demographic density showed high concentrations of TCol and TP, while clusters influenced by forestry and agriculture had better water quality. In the rainy season, clusters with urban influence showed problems with TCol and TP, in addition to some characteristics in each group, such as high TDS, NO3-, and BOD. Forested areas showed high DO, and clusters under agricultural influence had higher concentrations of TCol, BOD, and NO3- concerning forested regions. The troubling state of sanitation in GBHR occurs in metropolitan regions due to lack of a formal sanitation system.
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Monitoreo del Ambiente , Calidad del Agua , Brasil , Monitoreo del Ambiente/métodos , Bahías , Contaminantes Químicos del Agua/análisis , Fósforo/análisis , Nitratos/análisis , Estaciones del Año , Análisis MultivarianteRESUMEN
Atmospheric nitrogen (N) deposition could affect the structure and function of terrestrial plants. Non-N2-fixing lichens are used to monitor atmospheric N deposition because they rely on the deposited inorganic N (i.e., ammonium and nitrate) as N sources. However, the uptake capacities of lichen on ammonium and nitrate remain unclear, which hinders the application of lichen N content to accurate bioindication of atmospheric N deposition levels. We investigated ammonium and nitrate uptake capacities of Cladonia rangiferina, which was treated with ammonium alone, nitrate alone, and ammonium and nitrate mixture solutions with different mixing ratios under light and dark conditions. The results showed that N uptake rates increased with ammonium and nitrate concentrations in solutions and generally followed the Michaelis-Menten saturation kinetics. Ammonium uptake of C. rangiferina showed higher values of affinity, and was more efficient than the nitrate uptake. Both rates and amounts of nitrate uptake decreased with increasing ratios of ammonium to nitrate in solutions, while ammonium uptake showed no substantial variations, indicating an inhibition of ammonium on nitrate uptake capability. The darkness significantly decreased the maximum uptake rate and efficiency of nitrate, but had much weaker effects on lichen ammonium uptake. These findings highlight the preference of lichen on ammonium as a key N uptake strategy. It is thus necessary to consider the main types of atmospheric inorganic N deposition when using lichens to monitor atmospheric N pollution levels and evaluate N deposition based on lichen ecophysiology.
Asunto(s)
Compuestos de Amonio , Líquenes , Nitratos , Nitrógeno , Nitratos/metabolismo , Nitratos/análisis , Nitrógeno/metabolismo , Líquenes/metabolismo , Compuestos de Amonio/metabolismo , Cinética , Monitoreo del Ambiente/métodos , Compuestos de Amonio Cuaternario/metabolismo , Contaminantes Atmosféricos/metabolismo , Contaminantes Atmosféricos/análisisRESUMEN
Identifying and quantifying water nitrate pollution is crucial for managing aquatic environment of a bay. Dongshan Bay, a significant semi-enclosed bay in the southeastern coastal area of Fujian Province, features mangrove and coral reef ecosystems at its estuary and bay mouth, respectively. Dongshan Bay is impacted by human activities such as mariculture. We quantified and analyzed nitrate pollution status in the surface waters of Dongshan Bay by measuring physicochemical parameters, stable isotopes (δ15N-NO3-, δ18O-NO3- and δ15N-NH4+) of the surface waters, and using statistical methods including the MixSIAR isotope mixing model. The results showed that the concentrations of chlorophyll a and dissolved inorganic nitrogen in the surface waters exhibited a noticeable gradient change, decreasing from the estuary of the Zhangjiang River to the mouth of Dongshan Bay. The maximum concentrations of chlorophyll a, NH4+, NO3- and NO2- were 45.2 µg·L-1, 52.67 µmol·L-1, 379.2 µmol·L-1 and 3.93 µmol·L-1, respectively. The nitrogen and oxygen isotope values of NH4+ and NO3- in the surface waters showed significant spatial variations. According to the MixSIAR model results, nitrogen sources in the surface waters of Dongshan Bay were mainly freshwater inputs of the Zhangjiang River estuary, aquaculture wastewater, and groundwater. The freshwater input from the Zhangjiang River estuary contributed the most (25.2%), while aquaculture wastewater, groundwater and urban sewage accounted for 24.6%, 19.0%, and 15.1%, respectively. It is evident that freshwater input from the Zhangjiang River estuary is the primary source of nitrate in the surface waters of Dongshan Bay.
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Bahías , Monitoreo del Ambiente , Nitratos , Isótopos de Nitrógeno , Agua de Mar , Contaminantes Químicos del Agua , Nitratos/análisis , China , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente/métodos , Isótopos de Nitrógeno/análisis , Agua de Mar/análisis , Agua de Mar/química , Clorofila/análisis , Clorofila A/análisis , Isótopos de Oxígeno/análisisRESUMEN
Good quality water for human consumption, irrigation, and industrial use is very important. Today, around the world, water is contaminated by natural processes and human activities. This study aimed to evaluate the suitability of groundwater for drinking and irrigation, identify the source of fluoride and nitrate contamination, and assess the human health risks around the Cauvery River basin in southern India. A total of 30 groundwater samples were collected and analyzed for hydrochemical parameters, including EC, TDS, pH, Ca, Mg, Na, K, HCO3, Cl, SO4, NO3, and F-. The majority of groundwater samples in the study area are used for drinking and irrigation. The pH of groundwater in the study area was observed to be dominantly alkaline. The levels of TDS, Ca, Na, K, F, and TH exceeded the permissible limits recommended by BIS and WHO. Fluoride and nitrate levels in groundwater exceeded the permissible limits for drinking purposes in 43% and 50% of the samples, respectively. The excessive concentration of fluoride and nitrate in groundwater could pose serious human health problems. Fluoride and nitrate concentrations in groundwater vary between 0.1 and 2 mg/l and 12 and 95 mg/l, respectively. Based on the computation of the drinking water quality index, about 73% of groundwater samples were classified as excellent to good. Health risk was assessed for infants, children, and adults using non-carcinogenic risk indices such as hazard quotients (HQ), hazard indexes (HI), total hazard indices (THI), and carcinogenic risk indices (CR). Infants, children, and adults have different total hazards indexes ranging from 1.508 to 5.733, 1.579 to 6.003, and 0.011 to 0.046, respectively. Health risk assessment results indicated that the hazard index and hazard quotient were above the recommended limit of > 1 in most of the samples for infants and children. Non-carcinogenic risk and carcinogenic risks were more likely to affect infants and children rather than adults through ingestion of contaminated water.
Asunto(s)
Monitoreo del Ambiente , Fluoruros , Agua Subterránea , Nitratos , Ríos , Contaminantes Químicos del Agua , Calidad del Agua , India , Humanos , Fluoruros/análisis , Nitratos/análisis , Contaminantes Químicos del Agua/análisis , Agua Subterránea/química , Medición de Riesgo , Ríos/química , Agua Potable/químicaRESUMEN
Polymesoda erosa is a mangrove clam known for its water filtration ability. This clam was investigated for its bioremediation potential and growth in synthetic wastewater during 40 days of incubation. Variation in the nutrient composition of water, biochemical composition of the clams, and metagenomic analysis of the microorganisms associated with clam tissue were carried out. Significant differences in the concentration of ammonia (p ≤ 0.01), nitrite (p ≤ 0.001), and nitrate (p ≤ 0.05) in the wastewater were observed between day 0 and day 40. A reduction of approximately 89% in ammonia concentration at the end of the experiment was recorded indicating nitrification activity. However, biochemical parameters showed negligible differences before and after the incubation experiment. Thus suggesting that the chemosynthetic-based nutrition aids in the survival of the clam as no organic matter was added to the medium. The substantial decline in levels of ammonia in the presence of clams as compared to its absence suggests the significant role of clams in improving the water quality. Furthermore, the metagenomic analysis of the gill tissue of P. erosa revealed ~ 50% of the microbial population to consist of nitrifiers. The study highlights the contribution by the nitrifers associated with the clams not only to its growth and resilience but also to bioremediation.
Asunto(s)
Amoníaco , Biodegradación Ambiental , Bivalvos , Nitrificación , Aguas Residuales , Animales , Bivalvos/metabolismo , Bivalvos/microbiología , Amoníaco/metabolismo , Aguas Residuales/microbiología , Contaminantes Químicos del Agua/metabolismo , Nitritos/metabolismo , Nitratos/metabolismo , Eliminación de Residuos Líquidos/métodosRESUMEN
Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL-1). At this combination, biomass were about 0.2 mg/mL-1 carbohydrates, 0.085 mg/mL-1 proteins, and 0.16 mg/mL-1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1.
Asunto(s)
Bacillus , Biocombustibles , Biomasa , Carbonatos , Hidrógeno , Nitratos , Hidrógeno/metabolismo , Bacillus/metabolismo , Nitratos/metabolismo , Carbonatos/metabolismo , Fermentación , Chlorophyta/metabolismo , Chlorophyta/crecimiento & desarrollo , Fotosíntesis , Ácidos Grasos/metabolismoRESUMEN
Goodeinae is a subfamily of critically endangered fish native to central Mexico. Populations of Skiffia lermae, a species belonging to this subfamily, have significantly decreased in the past two decades. A previous study showed that S. lermae is sensitive to acute nitrate-nitrogen (NO3-N) exposure, leading to noticeable changes in both behavioral and histopathological bioindicators. The aim herein was to determine the vulnerability of S. lermae to NO3-N exposure at realistic concentrations registered in freshwater ecosystems in central Mexico where the species was historically reported. Offspring of S. lermae were chronically exposed during 60 days to concentrations of 5, 10 and 20 mg NO3-N/L, with 2 mg NO3-N/L used as the reference value (control). Survival rate, feeding behavior, aquatic surface respiration, body growth, scaled mass index, immature red blood cells, as well as histopathological changes in branchial, hepatic and gonadal tissues were evaluated. Additionally, this study analyzed water quality in freshwater ecosystems where S. lermae presently persists. The results showed decreased survival as NO3-N concentration increased, as well as increased feeding latency, aquatic surface respiration and histological damage in the gills and liver. These organs showed differential sex-dependent responses to NO3-N exposure; females were more sensitive than males. In the ovaries, a decreased density of stage III oocytes was associated with increased NO3-N concentrations. No changes were observed in body growth and number of immature red blood cells. Concentrations recorded in the three freshwater ecosystems that S. lermae inhabit were below 2 mg NO3-N/L. Together, the results could explain why the species has disappeared from more contaminated freshwater ecosystems where NO3-N levels exceed 5 mg/L. Moreover, the study warns about the risks of increasing NO3-N concentrations in the current sites where the species lives.
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Especies en Peligro de Extinción , Nitratos , Reproducción , Contaminantes Químicos del Agua , Animales , Nitratos/análisis , Femenino , Masculino , México , Reproducción/efectos de los fármacos , Contaminantes Químicos del Agua/efectos adversos , Contaminantes Químicos del Agua/análisis , Agua Dulce , EcosistemaRESUMEN
The high water consumption in agriculture has led to an obvious water crisis in this sector, and the use of unconventional water sources, especially agricultural drains, is considered necessary. For this purpose, the present study was carried out to evaluate the efficiency of biological filters with different types of substrates for treating agricultural wastewater in Khuzestan province, located in the south of Iran, to use receptive resources and reuse them in agriculture. Next, the efficiency of four types of biological filters for treating agricultural drainage water with different retention times was evaluated. Sawdust, cotton stalks, wheat straw, stubble, and rice husk were used as filters. Qualitative factors included agricultural pesticides (Atrazine, Randup, Paraquat, and 2, 4-D) and nutrients (nitrate, nitrogen, phosphate, and phosphorus). By examining the trend of increasing the retention time and the corresponding removal percentage, it was observed that the retention time has a direct relationship with the amount of removal efficiency of nutrients and agricultural toxins. As the residence time increases, the average amount of nutrient compounds in different filters decreases, and their removal percentage increases. The highest removal percentage of nitrate, total nitrogen, phosphate, and total phosphorus was 74.03, 71.66, 57.97, and 61.85% in the sawdust filter and was assigned to 10 days. The highest percentage of removal of Atrazine, Tofudi, Paraquat, and Roundup toxins with a removal efficiency of 91.73, 84.27, 89.81, and 88.46% was also observed in the treatment of sawdust for 10 days. The sawdust filter showed a good performance in removing the parameters of agricultural toxins and nutrient compounds in a retention time of 10 days compared to other filters and retention times. As a general result, the sawdust filter can be cited as a reliable substrate with acceptable efficiency compared to other filters.
Asunto(s)
Agricultura , Filtración , Plaguicidas , Contaminantes Químicos del Agua , Purificación del Agua , Agricultura/métodos , Plaguicidas/aislamiento & purificación , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Filtración/métodos , Fósforo/análisis , Fósforo/aislamiento & purificación , Nitrógeno/análisis , Nitrógeno/aislamiento & purificación , Aguas Residuales/química , Nutrientes/análisis , Irán , Nitratos/análisis , Nitratos/aislamiento & purificación , Fosfatos/análisis , Fosfatos/aislamiento & purificaciónRESUMEN
Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile E. coli (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO3)2-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their primo approach to the surface (< 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.
Asunto(s)
Escherichia coli , Hidrodinámica , Escherichia coli/fisiología , Propiedades de Superficie , Flagelos/fisiología , Flagelos/metabolismo , Movimiento , Níquel/química , Nitratos/metabolismo , Nitratos/químicaRESUMEN
Nitrate-dependent anaerobic methane oxidation (Nitrate-DAMO) is a novel and sustainable process that removes both nitrogen and methane. Previously, the metabolic pathway of Nitrate-DAMO has been intensively studied with some results. However, the production and consumption of nitrous oxide (N2O) in the Nitrate-DAMO system were widely disregarded. In this study, a Nitrate-DAMO system was used to investigate the effect of operational parameters (C/N ratio, pH, and temperature) on N2O accumulation, and the optimal operating conditions were determined (C/N = 3, pH = 6.5, and temperature = 20 °C). In this study, an enzyme kinetic model was used to fit the nitrate nitrogen degradation and the nitrous oxide production and elimination under different operating conditions. The thermodynamic model of N2O production and elimination in the system also has been constructed. Multiple linear regression analysis found that pH was the most important factor influencing N2O accumulation. The Metagenomics sequencing results showed that alkaline pH promoted the abundance of Nor genes and denitrifying bacteria, which were significantly and positively correlated with N2O emissions. And alkaline pH also promoted the production of Mdo genes related to the N2O-driven AOM reaction, indicating that part of the N2O was consumed by denitrifying bacteria and the other part was consumed by the N2O-driven AOM reaction. These findings reveal the mechanism of N2O production and consumption in DAMO systems and provide a theoretical basis for reducing N2O production and greenhouse gas emissions in actual operation.
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Metano , Nitratos , Óxido Nitroso , Óxido Nitroso/metabolismo , Nitratos/metabolismo , Cinética , Metano/metabolismo , Oxidación-Reducción , Anaerobiosis , Nitrógeno/metabolismo , Desnitrificación , Bacterias/metabolismoRESUMEN
Dietary inorganic nitrate lowers blood pressure (BP) in healthy individuals through improved nitric oxide (NO) bioavailability. However, there is limited evidence examining the long-term effects of dietary nitrate for managing hypertension. We aimed to determine whether the sustained intake of dietary nitrate improved BP and cardiovascular disease (CVD) risk factors in individuals with early-stage hypertension. The Dietary Nitrate (NO3) on BP and CVD Risk Factors (DINO3) Trial was a multi-center, double-blinded, parallel, randomized, controlled trial in participants with elevated BP. Participants were supplemented with high-nitrate (HN) (~400 mg nitrate) or low-nitrate (LN) vegetable powder (~50 mg nitrate) on top of their usual diets for 16 weeks. The primary outcome was office systolic BP at 16 weeks. The secondary outcomes were 24 h ambulatory BP, central BP, heart-rate-corrected augmentation index (AIx75), carotid-femoral pulse wave velocity (cf-PWV), lipids, and high-sensitivity C-reactive protein (hs-CRP). Sixty-six participants were randomized at baseline (39M:27F, age: 51.5 ± 10.8 years, BMI:27.9 ± 3.2 kg/m2). In an intention-to-treat analysis, no differences were observed between HN and LN groups in terms of office systolic BP at 16 weeks (3.91 ± 3.52 mmHg, p = 0.27) or secondary outcomes. In this exploratory study, sustained HN vegetable supplementation did not exhibit more favorable vascular effects than LN vegetable supplementation in individuals with elevated BP.
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Presión Sanguínea , Suplementos Dietéticos , Hipertensión , Nitratos , Verduras , Humanos , Persona de Mediana Edad , Femenino , Nitratos/administración & dosificación , Masculino , Método Doble Ciego , Presión Sanguínea/efectos de los fármacos , Hipertensión/dietoterapia , Adulto , Resultado del Tratamiento , Análisis de la Onda del PulsoRESUMEN
Nitrites are food additives used in meatfor their bacteriological, technological and sensory properties.However, they are suspected to be involved in the formation of various mutagenic nitroso compounds (NOCs).With a view to reducing the use of nitrite in meat products to improve the healthiness thereof, the formation of NOCs was studied during dynamic in vitro digestion ofcooked and recooked meats preparedwith various levels of nitrite. Residual nitrite and nitrate and NOCs were evaluated in the gastric and ileal compartments.In the absence of added nitrite, basalnitrosation and nitrosylation were detected, probably due to the oxidation of ammonium salts present in the gastric fluid. Nitrosamines, nitrosyl heme and nitrosothiols displayed different kinetics of formation and degradation,reflecting a possible transfer of nitric oxide from one substrate to another. A protective effect of nitrite on lipid oxidation was also observed during digestion.
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Culinaria , Digestión , Productos de la Carne , Nitritos , Compuestos Nitrosos , Oxidación-Reducción , Nitritos/química , Productos de la Carne/análisis , Nitrosación , Animales , Compuestos Nitrosos/química , Nitratos/química , Porcinos , Manipulación de Alimentos/métodosRESUMEN
Detecting chemical signals is important for identifying food sources and avoiding harmful agents. Like many animals, C. elegans use olfaction to chemotax towards their main food source, bacteria. However, little is known about the bacterial compounds governing C. elegans attraction to bacteria and the physiological importance of these compounds to bacteria. Here, we address these questions by investigating the function of a small RNA, P11, in the pathogen, Pseudomonas aeruginosa, that was previously shown to mediate learned pathogen avoidance. We discovered that this RNA also affects the attraction of untrained C. elegans to P. aeruginosa and does so by controlling production of ammonia, a volatile odorant produced during nitrogen assimilation. We describe the complex regulation of P. aeruginosa nitrogen assimilation, which is mediated by a partner-switching mechanism involving environmental nitrates, sensor proteins, and P11. In addition to mediating C. elegans attraction, we demonstrate that nitrogen assimilation mutants perturb bacterial fitness and pathogenesis during C. elegans infection by P. aeruginosa. These studies define ammonia as a major mediator of trans-kingdom signaling, implicate nitrogen assimilation as important for both bacteria and host organisms, and highlight how a bacterial metabolic pathway can either benefit or harm a host in different contexts.
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Amoníaco , Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Nitrógeno , Pseudomonas aeruginosa , Caenorhabditis elegans/microbiología , Caenorhabditis elegans/metabolismo , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/fisiología , Animales , Nitrógeno/metabolismo , Amoníaco/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/metabolismo , Nitratos/metabolismo , Transducción de Señal , Interacciones Huésped-Patógeno , QuimiotaxisRESUMEN
In sweet potato, rational nitrogen (N) assimilation and distribution are conducive to inhibiting vine overgrowth. Nitrate (NO3-) is the main N form absorbed by roots, and cultivar is an important factor affecting N utilization. Herein, a hydroponic experiment was conducted that included four NO3- concentrations of 0 (N0), 4 (N1), 8 (N2) and 16 (N3) mmol L-1 with two cultivars of Jishu26 (J26, N-sensitive) and Xushu32 (X32, N-tolerant). For J26, with increasing NO3- concentrations, the root length and root surface area significantly decreased. However, no significant differences were observed in these parameters for X32. Higher NO3- concentrations upregulated the expression levels of the genes that encode nitrate reductase (NR2), nitrite reductase (NiR2) and nitrate transporter (NRT1.1) in roots for both cultivars. The trends in the activities of NR and NiR were subject to regulation of NR2 and NiR2 transcription, respectively. For both cultivars, N2 increased the N accumulated in leaves, growth points and roots. For J26, N3 further increased the N accumulation in these organs. Under higher NO3- nutrition, compared with X32, J26 exhibited higher expression levels of the NiR2, NR2 and NRT1.1 genes, a higher influx NO3- rate in roots, and higher activities of NR and NiR in leaves and roots. Conclusively, the regulated effects of NO3- supplies on root growth and NO3- utilization were more significant for J26. Under high NO3- conditions, J26 exhibited higher capacities of NO3- absorption and distributed more N in leaves and in growth points, which may contribute to higher growth potential in shoots and more easily cause vine overgrowth.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Ipomoea batatas , Nitratos , Nitrógeno , Raíces de Plantas , Nitratos/metabolismo , Ipomoea batatas/metabolismo , Ipomoea batatas/genética , Ipomoea batatas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética , Nitrógeno/metabolismo , Nitrato-Reductasa/metabolismo , Nitrato-Reductasa/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/genética , Transportadores de Nitrato , Hidroponía , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Nitrito Reductasas/metabolismo , Nitrito Reductasas/genética , Proteínas de Transporte de Anión/metabolismo , Proteínas de Transporte de Anión/genéticaRESUMEN
The lateral root (LR) is an essential component of the plant root system, performing important functions for nutrient and water uptake in plants and playing a pivotal role in cereal crop productivity. Nitrate (NO3-) is an essential nutrient for plants. In this study, wheat plants were grown in 1/2 strength Hoagland's solution containing 5 mM NO3- (check; CK), 0.1 mM NO3- (low NO3-; LN), or 0.1 mM NO3- plus 60 mg/L 2,3,5-triiodobenzoic acid (TIBA) (LNT). The results showed that LN increased the LR number significantly at 48 h after treatment compared with CK, while not increasing the root biomass, and LNT significantly decreased the LR number and root biomass. The transcriptomic analysis showed that LN induced the expression of genes related to root IAA synthesis and transport and cell wall remodeling, and it was suppressed in the LNT conditions. A physiological assay revealed that the LN conditions increased the activity of IAA biosynthesis-related enzymes, the concentrations of tryptophan and IAA, and the activity of cell wall remodeling enzymes in the roots, whereas the content of polysaccharides in the LRP cell wall was significantly decreased compared with the control. Fourier-transform infrared spectroscopy and atomic microscopy revealed that the content of cell wall polysaccharides decreased and the cell wall elasticity of LR primordia (LRP) increased under the LN conditions. The effects of LN on IAA synthesis and polar transport, cell wall remodeling, and LR development were abolished when TIBA was applied. Our findings indicate that NO3- starvation may improve auxin homeostasis and the biological properties of the LRP cell wall and thus promote LR initiation, while TIBA addition dampens the effects of LN on auxin signaling, gene expression, physiological processes, and the root architecture.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos , Nitratos , Raíces de Plantas , Transducción de Señal , Triticum , Triticum/metabolismo , Triticum/genética , Triticum/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/efectos de los fármacos , Nitratos/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Pared Celular/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Organogénesis de las Plantas/genética , Perfilación de la Expresión GénicaRESUMEN
OBJECTIVES: In this review, we explored potential associations between NO and its derivatives, nitrite and nitrate, with periodontal and cardiovascular diseases, with special emphasis on the former. By providing a state-of-the-art and integrative understanding of this topic, we aimed to shed light on the potential role of these three nitrogen oxides in the periodontitis-hypertension nexus, identify knowledge gaps, and point out critical aspects of the experimental methodologies. MATERIALS AND METHODS: A comprehensive literature review was conducted on human salivary and plasma concentrations of nitrate and nitrite, and their impact on periodontal and cardiovascular health. RESULTS: A nitrate-rich diet increases nitrate and nitrite levels in saliva and plasma, promoting oral health by favorably altering the oral microbiome. Chlorhexidine (CHX) mouthrinses disrupt the nitrate-nitrite-NO pathway, reducing NO bioavailability, and potentially affecting blood pressure. This is because CHX eliminates nitrate-reducing bacteria, which are essential for NO production. Although endogenous NO production may be insufficient, the nitrate-nitrite-NO pathway plays a critical role in maintaining appropriate endothelial function, which is balanced by the microbiome and dietary nitrate intake. Dietary nitrate supplementation may lead to beneficial changes in the oral microbiome, thereby increasing the NO bioavailability. However, NO bioavailability can be compromised by reactive oxygen species (ROS) and the uncoupling of endothelial nitric oxide synthase (eNOS), leading to further ROS generation and creating a detrimental cycle. Studies on NO and periodontal disease have shown increased nitrite concentrations in patients with periodontal disease, although these studies have some methodological limitations. In terms of blood pressure, literature suggests that CHX mouthrinses may reduce the capacity of nitrate-reducing bacteria, potentially leading to an increase in blood pressure. CONCLUSIONS: Several studies have suggested an association between NO levels and the development of cardiovascular and periodontal diseases. However, the exact mechanisms linking these diseases remains to be fully elucidated. CLINICAL RELEVANCE: Nitric oxide (NO) is a signaling molecule that plays a crucial role in several physiological processes such as vascular homeostasis, inflammation, immune cell activity, and pathologies such as hypertension and periodontitis.
Asunto(s)
Nitratos , Óxido Nítrico , Enfermedades Periodontales , Humanos , Óxido Nítrico/metabolismo , Presión Sanguínea , Nitritos , Hipertensión , Saliva/metabolismo , Saliva/química , Saliva/microbiología , Enfermedades CardiovascularesRESUMEN
BACKGROUND: Random-pattern skin flaps are commonly used to repair skin tissue defects in surgical tissue reconstruction. However, flap necrosis in the distal area due to ischemia injury is still challenging for its applications in plastic surgery. The complications of diabetes will further increase the risk of infection and necrosis. METHODS: This study induced type 2 diabetes mellitus (T2DM) rats with a high-fat diet and STZ. The survival rate of the skin flap was observed by adding inorganic sodium nitrate to drinking water. Histology and immunohistochemistry were used to detect the damage to the skin flap. The nitrate content was measured by total nitric oxide and nitrate/nitrite parameter assay. Dihydroethidium and malondialdehyde (MDA) assays were used to value oxidative stress. Rat colon feces were collected for 16s rRNA gene sequence. RESULTS: Our studies showed that nitrate administration leads to anti-obesity and anti-diabetic effects. Nitrate directly increased the survival area of skin flaps in diabetic rats and mean blood vessel density by enhancing angiogenesis, inhibiting apoptosis, and reducing oxidative stress. The 16s rRNA sequence revealed that nitrate may regulate the homeostasis of the gut microbiota and re-store energy metabolism. CONCLUSION: Dietary nitrate has been shown to maintain the homeostasis of oxidative stress and gut microbiota to promote flap survival in rats with T2DM.