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1.
Nitric Oxide ; 103: 29-30, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32712272

RESUMO

Most outcomes of COVID-19 are associated with dysfunction of the vascular system, particularly in the lung. Inhalation of nitric oxide (NO) gas is currently being investigated as a treatment for patients with moderate to severe COVID-19. In addition to the expected vasodilation effect, it has been also suggested that NO potentially prevents infection by SARS-CoV-2. Since NO is an unstable radical molecule that is easily oxidized by multiple mechanisms in the human body, it is practically difficult to control its concentration at lesions that need NO. Inorganic nitrate and/or nitrite are known as precursors of NO that can be produced through chemical as well enzymatic reduction. It appears that this NO synthase (NOS)-independent mechanism has been overlooked in the current developing of clinical treatments. Here, I suggest the missing link between nitrate and COVID-19 in terms of hypoxic NO generation.


Assuntos
Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Pneumonia Viral/tratamento farmacológico , Antivirais/metabolismo , Ácido Ascórbico/química , Ácido Ascórbico/uso terapêutico , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/prevenção & controle , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Humanos , Nitratos/sangue , Nitritos/sangue , Nitritos/química , Pandemias/prevenção & controle , Pneumonia Viral/metabolismo , Pneumonia Viral/prevenção & controle , Vasodilatação/efeitos dos fármacos
2.
PLoS One ; 15(7): e0235975, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649704

RESUMO

Rice cultivar "Weiyou916" (Oryza sativa L. ssp. Indica) were cultured with control (10 mM NO3-) and nitrate deficient solution (0 mM NO3-) for four weeks. Nitrogen (N) deficiency significantly decreased the content of N and P, dry weight (DW) of the shoots and roots, but increased the ratio of root to shoot in O. sativa. N deficiency decreased the photosynthesis rate and the maximum quantum yield of primary photochemistry (Fv/Fm), however, increased the intercellular CO2 concentration and primary fluorescence (Fo). N deficiency significantly increased the production of H2O2 and membrane lipid peroxidation revealed as increased MDA content in O. sativa leaves. N deficiency significantly increased the contents of starch, sucrose, fructose, and malate, but did not change that of glucose and total soluble protein in O. sativa leaves. The accumulated carbohydrates and H2O2 might further accelerate biosynthesis of lignin in O. sativa leaves under N limitation. A total of 1635 genes showed differential expression in response to N deficiency revealed by Illumina sequencing. Gene Ontology (GO) analysis showed that 195 DEGs were found to highly enrich in nine GO terms. Most of DEGs involved in photosynthesis, biosynthesis of ethylene and gibberellins were downregulated, whereas most of DEGs involved in cellular transport, lignin biosynthesis and flavonoid metabolism were upregulated by N deficiency in O. sativa leaves. Results of real-time quantitative PCR (RT-qPCR) further verified the RNA-Seq data. For the first time, DEGs involved oxygen-evolving complex, phosphorus response and lignin biosynthesis were identified in rice leaves. Our RNA-Seq data provided a global view of transcriptomic profile of principal processes implicated in the adaptation of N deficiency in O. sativa and shed light on the candidate direction in rice breeding for green and sustainable agriculture.


Assuntos
Flavonoides/metabolismo , Lignina/metabolismo , Nitratos/metabolismo , Oryza/genética , Fotossíntese , Carboidratos/análise , Clorofila A/química , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Oryza/metabolismo , Oxirredução , Folhas de Planta/genética , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , RNA de Plantas/química , RNA de Plantas/metabolismo , Análise de Sequência de RNA
3.
Proc Natl Acad Sci U S A ; 117(27): 15504-15510, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571954

RESUMO

Earth system models (ESMs) project that global warming suppresses biological productivity in the Subarctic Atlantic Ocean as increasing ocean surface buoyancy suppresses two physical drivers of nutrient supply: vertical mixing and meridional circulation. However, the quantitative sensitivity of productivity to surface buoyancy is uncertain and the relative importance of the physical drivers is unknown. Here, we present a simple predictive theory of how mixing, circulation, and productivity respond to increasing surface buoyancy in 21st-century global warming scenarios. With parameters constrained by observations, the theory suggests that the reduced northward nutrient transport, owing to a slower ocean circulation, explains the majority of the reduced productivity in a warmer climate. The theory also informs present-day biases in a set of ESM simulations as well as the physical underpinnings of their 21st-century projections. Hence, this theoretical understanding can facilitate the development of improved 21st-century projections of marine biogeochemistry and ecosystems.


Assuntos
Organismos Aquáticos/metabolismo , Ecossistema , Aquecimento Global , Modelos Teóricos , Água do Mar/química , Organismos Aquáticos/efeitos da radiação , Oceano Atlântico , Atmosfera/análise , Atmosfera/química , Planeta Terra , Monitorização de Parâmetros Ecológicos/estatística & dados numéricos , Gases de Efeito Estufa/efeitos adversos , Gases de Efeito Estufa/análise , Nitratos/análise , Nitratos/metabolismo , Nutrientes/metabolismo , Luz Solar , Movimentos da Água
4.
Proc Natl Acad Sci U S A ; 117(26): 15343-15353, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32546525

RESUMO

Ion transporters are key players of cellular processes. The mechanistic properties of ion transporters have been well elucidated by biophysical methods. Meanwhile, the understanding of their exact functions in cellular homeostasis is limited by the difficulty of monitoring their activity in vivo. The development of biosensors to track subtle changes in intracellular parameters provides invaluable tools to tackle this challenging issue. AtCLCa (Arabidopsis thaliana Chloride Channel a) is a vacuolar NO3 -/H+ exchanger regulating stomata aperture in A thaliana Here, we used a genetically encoded biosensor, ClopHensor, reporting the dynamics of cytosolic anion concentration and pH to monitor the activity of AtCLCa in vivo in Arabidopsis guard cells. We first found that ClopHensor is not only a Cl- but also, an NO3 - sensor. We were then able to quantify the variations of NO3 - and pH in the cytosol. Our data showed that AtCLCa activity modifies cytosolic pH and NO3 - In an AtCLCa loss of function mutant, the cytosolic acidification triggered by extracellular NO3 - and the recovery of pH upon treatment with fusicoccin (a fungal toxin that activates the plasma membrane proton pump) are impaired, demonstrating that the transport activity of this vacuolar exchanger has a profound impact on cytosolic homeostasis. This opens a perspective on the function of intracellular transporters of the Chloride Channel (CLC) family in eukaryotes: not only controlling the intraorganelle lumen but also, actively modifying cytosolic conditions.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Canais de Cloreto/metabolismo , Citosol/química , Homeostase/fisiologia , Nitratos/química , Proteínas de Arabidopsis/genética , Canais de Cloreto/genética , Citosol/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Concentração de Íons de Hidrogênio , Nitratos/metabolismo
5.
Sheng Wu Gong Cheng Xue Bao ; 36(6): 1150-1161, 2020 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-32597064

RESUMO

The aim of this study was to establish a novel technology using microalgae for NO3⁻ removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO3⁻ assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO3⁻ assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d⁻¹). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO3⁻ assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.


Assuntos
Proteínas de Algas , Chlorella , Nitratos , Nitrogênio , Purificação da Água , Proteínas de Algas/biossíntese , Biomassa , Nitratos/isolamento & purificação , Nitratos/metabolismo , Nitrogênio/metabolismo , Águas Residuárias/química , Purificação da Água/métodos
6.
Arch Biochem Biophys ; 689: 108453, 2020 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-32524996

RESUMO

Nitric oxide (NO) deficiency and NADPH oxidase plays key roles in endothelial dysfunction and atherosclerotic plaque formation. Recent evidence demonstrates that nitrate-nitrite-NO pathway in vivo exerts beneficial effects upon the cardiovascular system. We aimed to investigate the effects of dietary nitrate on endothelial function and atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice fed a high-fat diet. It was shown that dietary nitrate significantly attenuated aortic endothelial dysfunction and atherosclerosis in ApoE-/- mice. Mechanistic studies revealed that dietary nitrate significantly improved plasma nitrate/nitrite, inhibited vascular NADPH oxidase activity and oxidative stress in ApoE-/- mice, while xanthine oxidoreductase (XOR) expression and activity was enhanced in ApoE-/- mice in comparison with wide type animals. These beneficial effects of nitrate in ApoE-/- mice were abolished by PTIO (NO scavenger) and significantly prevented by febuxostat (XOR inhibitor). In the presence of nitrate, no further effect of apocynin (NADPH oxidase inhibitor) was observed, suggesting NADPH oxidase as a possible target. In vitro, NO donor significantly inhibited NADPH oxidase activity in vascular endothelial cells via the induction of heme oxygenase-1. Altogether, boosting this nitrate-nitrite-NO signaling pathway resulted in the decreases of vascular NADPH oxidase-derived oxidative stress and endothelial dysfunction, and consequently protected ApoE-/- mice against atherosclerosis. These findings may have novel nutritional implications for the preventive and therapeutic strategies against vascular endothelial dysfunction in atherosclerotic disease.


Assuntos
Aterosclerose/terapia , Endotélio Vascular/patologia , NADPH Oxidases/metabolismo , Nitratos/uso terapêutico , Animais , Apolipoproteínas E/genética , Aterosclerose/genética , Aterosclerose/metabolismo , Aterosclerose/patologia , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Masculino , Camundongos , Camundongos Knockout , Nitratos/metabolismo , Nitritos/metabolismo , Estresse Oxidativo
7.
Pharmacol Rev ; 72(3): 692-766, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32576603

RESUMO

In contrast to nitric oxide, which has well established and important roles in the regulation of blood flow and thrombosis, neurotransmission, the normal functioning of the genitourinary system, and the inflammation response and host defense, its oxidized metabolites nitrite and nitrate have, until recently, been considered to be relatively inactive. However, this view has been radically revised over the past decade and more. Much evidence has now accumulated demonstrating that nitrite serves as a storage form of nitric oxide, releasing nitric oxide preferentially under acidic and/or hypoxic conditions but also occurring under physiologic conditions: a phenomenon that is catalyzed by a number of distinct mammalian nitrite reductases. Importantly, preclinical studies demonstrate that reduction of nitrite to nitric oxide results in a number of beneficial effects, including vasodilatation of blood vessels and lowering of blood pressure, as well as cytoprotective effects that limit the extent of damage caused by an ischemia/reperfusion insult, with this latter issue having been translated more recently to the clinical setting. In addition, research has demonstrated that the other main metabolite of the oxidation of nitric oxide (i.e., nitrate) can also be sequentially reduced through processing in vivo to nitrite and then nitrite to nitric oxide to exert a range of beneficial effects-most notably lowering of blood pressure, a phenomenon that has also been confirmed recently to be an effective method for blood pressure lowering in patients with hypertension. This review will provide a detailed description of the pathways involved in the bioactivation of both nitrate and nitrite in vivo, their functional effects in preclinical models, and their mechanisms of action, as well as a discussion of translational exploration of this pathway in diverse disease states characterized by deficiencies in bioavailable nitric oxide. SIGNIFICANCE STATEMENT: The past 15 years has seen a major revision in our understanding of the pathways for nitric oxide synthesis in the body with the discovery of the noncanonical pathway for nitric oxide generation known as the nitrate-nitrite-nitric oxide pathway. This review describes the molecular components of this pathway, its role in physiology, potential therapeutics of targeting this pathway, and their impact in experimental models, as well as the clinical translation (past and future) and potential side effects.


Assuntos
Nitratos/metabolismo , Nitratos/farmacologia , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Animais , Pressão Sanguínea/efeitos dos fármacos , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Transdução de Sinais/efeitos dos fármacos
8.
Proc Natl Acad Sci U S A ; 117(28): 16649-16659, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32586957

RESUMO

Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO3 - supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO3 - transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO3 - was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO3 - acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.


Assuntos
Proteínas de Transporte de Ânions/metabolismo , Glomeromycota/fisiologia , Micorrizas/fisiologia , Nitrogênio/metabolismo , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Transporte de Ânions/genética , Regulação da Expressão Gênica de Plantas , Nitratos/metabolismo , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Proteínas de Plantas/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Sorghum/genética , Sorghum/metabolismo , Sorghum/microbiologia , Zea mays/genética , Zea mays/metabolismo , Zea mays/microbiologia
9.
Chemosphere ; 257: 127251, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32512336

RESUMO

Heterotrophic anodic denitrification (HAD) in the single-chamber microbial fuel cell (MFC) is a promising nitrogen removal technology. In this paper, the benefit (anolyte pH increase) and challenge (substrate consumption) brought by the heterotrophic anodic denitrification process for the electricity generation of bufferless MFCs were studied for the first time. Substrate anaerobic hydrolysis dramatically decreased the anolyte pH to 5.1, which seriously restricted the electric power output of the Control. The anolyte pH of the heterotrophic anodic denitrification MFCs (HADMFCs) with 60 mg/L (HADMFC-60), 90 mg/L (HADMFC-90), and 120 mg/L (HADMFC-120) nitrate nitrogen (NO3--N), retained above 6.0, 6.5, and 6.8 in every running cycles, due to the protons (H+) consumption by nitrate reduction. In the HADMFC-60 and HADMFC-90, 17.6% and 26.1% of the total organic carbons (TOC) were used for the nitrate reduction, but their electric power output significantly increased. The maximum power densities of the HADMFC-60 and HADMFC-90 were 3.3 and 5.4 times higher than that of the Control. However, when the proportion of TOC consumption for nitrate reduction increased to 35.8%, substrate insufficiency became a serious limitation for the electricity generation. The Pmax of the HADMFC-120 dramatically decreased to 17.3 mW/m2. Dysgonomonas was the dominant electro-active genus, and Petrimonas, Acidovorax and Devosia appeared as the denitrifying bacteria genera.


Assuntos
Fontes de Energia Bioelétrica/microbiologia , Bactérias/metabolismo , Desnitrificação , Eletricidade , Eletrodos , Processos Heterotróficos , Concentração de Íons de Hidrogênio , Nitratos/metabolismo , Nitrogênio , Óxidos de Nitrogênio , Prótons
10.
Mol Genet Genomics ; 295(5): 1269-1279, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32561986

RESUMO

Aspergillus nidulans nrtA encodes a nitrate transporter that plays an important role in the [Formula: see text] assimilatory process. Many studies have focused on protein functions rather than gene regulation. The knowledge of nrtA[Formula: see text] uptake process, particularly in the regulation mechanism of transcription factors AreA and NirA on nrtA transcription, is very limited. Herein, we investigated the transcriptional regulation of nrtA in response to various N-sources in detail and characterized the promoter activity of nrtA. We confirmed that nrtA was induced by [Formula: see text] and repressed by preferred N-sources. Additionally, for the first time, we found that the transcription of nrtA increased under N-starvation conditions. AreA mediates nrtA transcription under both [Formula: see text] and N-starvation conditions, while NirA is effective only under [Formula: see text] conditions. All of the proposed AreA and NirA binding sites in the promoter region were capable of binding to their corresponding transcription factors in vitro. In vivo, all of the NirA binding sites showed regulation activities, but to AreA, only several of the initiation-codon-proximal binding sites participated in nrtA transcription. Moreover, the active binding sites contributed in different degrees of regulation strength to nrtA transcription, which is unrelated to the distance between the binding sites and initiation codon. These results provided an extensive map of nrtA promoter, defining the functional regulatory elements of A. nidulans nrtA.


Assuntos
Proteínas de Transporte de Ânions/genética , Proteínas de Transporte de Ânions/metabolismo , Aspergillus nidulans/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Nitratos/metabolismo , Proteínas de Transporte de Ânions/química , Aspergillus nidulans/genética , Sítios de Ligação , Proteínas Fúngicas/química , Regulação Fúngica da Expressão Gênica , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismo
11.
J Biosci Bioeng ; 130(2): 179-186, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32381439

RESUMO

The sediment-water interface is not only an important location for substrate conversion in a mariculture system, but also a major source of eutrophication. This study aimed to clarify the characteristics of inorganic nitrogen (ammonia, nitrite and nitrate) removal by Marichromatium gracile YL28 in the presence of both organic nitrogen and inorganic nitrogen. The results showed that, in the presence of peptone or urea, seaweed oligosaccharides (SOS) effectively enhanced the ammonia removal capacity of YL28 (6.42 mmol/L) and decreased the residual rate by 54.04% or 8.17%, respectively. With increasing peptone or urea concentrations, the removal of both ammonia and nitrate was gradually inhibited, and the residual rates of ammonia and nitrate reached 22.56-34.36% and 12.03-15.64% in the peptone system and 20.65-24.03% and 12.20-13.21% in the urea system, respectively. However, in the control group the residual rates of ammonia and nitrate reached 11.97% and 5.12%, respectively. In addition, the concentrations of peptone and urea did not affect nitrite removal, and YL28 displayed better cell growth and nitrogen removal activity in the presence of bait and SOS. Overall, the ability of YL28 to remove inorganic nitrogen was enhanced in the presence of organic nitrogen.


Assuntos
Aquicultura , Chromatiaceae/metabolismo , Nitrogênio/química , Nitrogênio/isolamento & purificação , Peptonas/farmacologia , Ureia/farmacologia , Água/química , Amônia/isolamento & purificação , Amônia/metabolismo , Desnitrificação/efeitos dos fármacos , Nitratos/isolamento & purificação , Nitratos/metabolismo , Nitritos/isolamento & purificação , Nitritos/metabolismo
12.
PLoS One ; 15(5): e0232767, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437364

RESUMO

Nitrogen (N) availability is an important factor regulating the feedback mechanisms of global change. This research uses a small Calamagrostis angustifolia wetland i = on the Sanjiang Plain of Northeast China as the research object and 15N tracer technology to study the effects of different nitrogen deposition levels (0 gN/m2, 4 gN/m2, and 8 gN/m2) through in situ controlled field experiments. Temporal and spatial distribution patterns of nitrogen in plants and soils and their short-term effects on nitrous oxide emissions fluxes were studied. The results showed that 1) the nitrogen content in the stems, leaves and roots of C. angustifolia decreased slowly with the growing season. Nitrogen application significantly increased the absorption of tracer nitrogen in the aboveground and underground plant parts (P<0.01), and the more nitrogen applied, the larger the absorption amount was (P<0.01). The absorbed amount accounted for 52%-86% of the total tracer nitrogen. 2) The tracer nitrogen in the soil did not show a significant change; the more nitrogen that was applied, the more nitrogen that was retained in the soil, and the tracer nitrogen adsorbed by the soil was mainly ammonium nitrogen. 3) The variation in the 15N-labeled nitric oxide emissions flux under different nitrogen treatments was consistent; nitrogen application increased the 15N-labeled nitric oxide emissions flux, but the difference between the low-nitrogen and high-nitrogen treatments was not significant (P>0.05).


Assuntos
Nitrogênio/metabolismo , Poaceae/metabolismo , Áreas Alagadas , China , Nitratos/metabolismo , Isótopos de Nitrogênio , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Caules de Planta/metabolismo , Solo/química , Fatores de Tempo
13.
Chemosphere ; 255: 126833, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387724

RESUMO

Understanding the transformation pattern of nitrogen (N) pollutants and its pathways in the prechlorinated raw water distribution system (PRWDS) is vital for controlling the stablitiy and safety of raw water qulity. This study investigated the N transformation, N functional genes and their correlations to find the N transformation pathways along the PRWDS. Results suggested that simultaneous nitrification, anaerobic ammonium oxidation and denitrification (SNAD) contribute to the N transformationin the PRWDS. Along the pipeline, anammox 16S rRNA (9.18 × 107-8.41 × 108 copies/g), limited by prechlorination, was the most abundant N functional genes and anammox process was the main pathway of ammonia nitrogen (NH4+-N). The decreasing NH4+-N was connected with Planctomycetes, Nitrospira and abundance of nxrA attributing to the joint effort of anammox and declined nitrification. The concentration of nitrate (NO3--N) increasing at first and then decreasing, was correlated positively with Sphingomonas. because of the declined nitritication and increased denitrification. Besides, the NO3--N→NO2--N process was considered to be primary NO3--N transformation pathways. Increases in the concentration of dissolved organic nitrogen (DON) and nitrite (NO2--N) observed in the PRWDS had positive correlation with relative abundance of Pseudomonas. We believe that prechlorination shaped the particular bacterialcharacteristics in biofilms and influenced the N transformation pathways indirectly, resulting in the varying N transformation rules in PRWDSs. Moreover, systematic and extended research is particularly vital for determining the effects of changes in source water quality and environmental conditions on bacterial community structure and N conversion along PRWDSs.


Assuntos
Nitrogênio/análise , Poluentes da Água/análise , Abastecimento de Água/estatística & dados numéricos , Amônia/metabolismo , Bactérias/metabolismo , Biofilmes , Reatores Biológicos/microbiologia , Desnitrificação , Poluentes Ambientais/metabolismo , Nitratos/metabolismo , Nitrificação , Nitritos/análise , Oxirredução , RNA Ribossômico 16S/metabolismo
14.
Chemosphere ; 253: 126693, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464770

RESUMO

Nitrate pollution presents a serious threat to the environment and public health. As an excellent heterotrophic denitrification carbon source, banana peel (a kind of agricultural waste) provides a feasible alternative to deal with the persistent high concentrations of nitrate pollution. Although the feasibility and economy of banana peel for denitrification have already been reported, the long-term stability and mechanism were still unclear. The coupling mechanism of organic matters and microorganism in the denitrification process was systematically investigated through a 17-cycle experiment. The results showed that significant NO3--N removal load and rate of 164.42 mg/g and 4.69 mg/(L·h) after long-term tests could be obtained. Organic matter analysis and 16S rRNA sequencing showed that the evolution of organic matter was dominated by Anaerolineaceae (fermenting bacteria), and, in the final step, the humification of organic matter was realized. Moreover, the presence of Lentimicrobium (denitrifying bacteria) was indispensable for the continuous removal of high concentrations of nitrate. The main functional gene of nitrogen transformation in this reaction system was NirS (haem-containing). This lab-scale heterotrophic denitrification process could contribute to a better understanding of the carbon and nitrogen cycles in the biogeochemical cycles to some extent, and it also provides a reference for the construction of highly efficient nitrate degradation reactors, based on agricultural wastes.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação , Musa , Bactérias/metabolismo , Carbono/metabolismo , Desnitrificação/genética , Processos Heterotróficos , Nitratos/metabolismo , Nitrogênio/metabolismo , Ciclo do Nitrogênio , RNA Ribossômico 16S/genética , Águas Residuárias/química
15.
PLoS One ; 15(4): e0232294, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32353025

RESUMO

Spring maize sowing occurs during a period of low temperature (LT) in Northeast China, and the LT suppresses nitrogen (N) metabolism and photosynthesis, further reducing dry matter accumulation. Diethyl aminoethyl hexanoate (DA-6) improves N metabolism; hence, we studied the effects of DA-6 on maize seedlings under LT conditions. The shoot and root fresh weight and dry weight decreased by 17.70%~20.82% in the LT treatment, and decreased by 5.81%~13.57% in the LT + DA-6 treatment on the 7th day, respectively. Exogenous DA-6 suppressed the increases in ammonium (NH4+) content and glutamate dehydrogenase (GDH) activity, and suppressed the decreases in nitrate (NO3-) and nitrite (NO2-) contents, and activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT) and transaminase activities. NiR activity was most affected by DA-6 under LT conditions. Additionally, exogenous DA-6 suppressed the net photosynthetic rate (Pn) decrease, and the suppressed the increases of superoxide anion radical (O2·-) generation rate and hydrogen peroxide (H2O2) content. Taken together, our results suggest that exogenous DA-6 mitigated the repressive effects of LT on N metabolism by improving photosynthesis and modulating oxygen metabolism, and subsequently enhanced the LT tolerance of maize seedlings.


Assuntos
Caproatos/farmacologia , Nitrogênio/metabolismo , Plântula/efeitos dos fármacos , Plântula/metabolismo , Zea mays/efeitos dos fármacos , Zea mays/metabolismo , Compostos de Amônio/metabolismo , China , Temperatura Baixa , Glutamato Sintase/metabolismo , Glutamato-Amônia Ligase/metabolismo , Peróxido de Hidrogênio/metabolismo , Nitrato Redutase/metabolismo , Nitratos/metabolismo , Nitrito Redutases/metabolismo , Nitritos/metabolismo , Fotossíntese/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/metabolismo
16.
Biochim Biophys Acta Mol Cell Res ; 1867(8): 118732, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32360667

RESUMO

Nitric oxide is an important neuromodulator in the CNS, and its production within neurons is modulated by NMDA receptors and requires a fine-tuned availability of L-arginine. We have previously shown that globally inhibiting protein synthesis mobilizes intracellular L-arginine "pools" in retinal neurons, which concomitantly enhances neuronal nitric oxide synthase-mediated nitric oxide production. Activation of NMDA receptors also induces local inhibition of protein synthesis and L-arginine intracellular accumulation through calcium influx and stimulation of eucariotic elongation factor type 2 kinase. We hypothesized that protein synthesis inhibition might also increase intracellular L-arginine availability to induce nitric oxide-dependent activation of downstream signaling pathways. Here we show that nitric oxide produced by inhibiting protein synthesis (using cycloheximide or anisomycin) is readily coupled to AKT activation in a soluble guanylyl cyclase and cGKII-dependent manner. Knockdown of cGKII prevents cycloheximide or anisomycin-induced AKT activation and its nuclear accumulation. Moreover, in retinas from cGKII knockout mice, cycloheximide was unable to enhance AKT phosphorylation. Indeed, cycloheximide also produces an increase of ERK phosphorylation which is abrogated by a nitric oxide synthase inhibitor. In summary, we show that inhibition of protein synthesis is a previously unanticipated driving force for nitric oxide generation and activation of downstream signaling pathways including AKT and ERK in cultured retinal cells. These results may be important for the regulation of synaptic signaling and neuronal development by NMDA receptors as well as for solving conflicting data observed when using protein synthesis inhibitors for studying neuronal survival during development as well in behavior and memory studies.


Assuntos
Proteína Quinase Dependente de GMP Cíclico Tipo II/metabolismo , Óxido Nítrico/metabolismo , Inibidores da Síntese de Proteínas/farmacologia , Retina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Arginina/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Embrião de Galinha , Galinhas , Proteína Quinase Dependente de GMP Cíclico Tipo II/genética , Quinase do Fator 2 de Elongação/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo , Nitratos/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Nitritos , Fosforilação
17.
Arch Microbiol ; 202(7): 1775-1784, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32363505

RESUMO

Enterobacter cloacae strain HNR was found to grow well and denitrify aerobically at high NO3--N concentrations. When the concentrations of NO3--N were 200, 300 and 500 mg/L, the removal efficiencies of NO3--N were 83%, 74.5% and 75%, respectively. More importantly, the intermediates accumulation of NO2--N and NH4+-N was not obvious during the aerobic denitrification processes, resulting in a high TN removal of 82%, 74% and 70%, respectively. Meanwhile, strain HNR also presented the ability of heterotrophic nitrification. With initial NH4+-N concentrations of 20 and 80 mg/L, the NH4+-N removal efficiency reached 78% and 76%, respectively. The key nitrate reductase enzyme gene relating to denitrification was successfully amplified by polymerase chain reaction (PCR) from strain HNR, and identified it as napA, which encodings the large catalytic subunit A of periplasmic nitrate reductase (NAPA). The sequence analysis of napA indicates that NAPA is a hydrophilic, non-transmembrane protein. The existence of napA might be crucial for strain HNR to denitrify nitrate under aerobic conditions. This study showed prospect to develop novel technology for nitrogen removal by application of E. cloacae strain HNR.


Assuntos
Desnitrificação/genética , Enterobacter cloacae/enzimologia , Enterobacter cloacae/genética , Nitrato Redutase/genética , Aerobiose , Enterobacter cloacae/metabolismo , Nitrato Redutase/metabolismo , Nitratos/metabolismo , Nitrogênio/metabolismo
18.
PLoS One ; 15(4): e0232056, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32324773

RESUMO

Nitrogen use efficiency (NUE) is the efficiency with which plants acquire and use nitrogen. Plants have high-affinity nitrate transport systems, which involve certain nitrate transporter (NRT) genes. However, limited data are available on the contribution of the NRT2/3 gene family in barley nitrate transport. In the present study, ten putative NRT2 and three putative NRT3 genes were identified using bioinformatics methods. All the HvNRT2/3 genes were located on chromosomes 3H, 5H, 6H or 7H. Remarkably, the presence of tandem repeats indicated that duplication events contributed to the expansion of the NRT2 gene family in barley. In addition, the HvNRT2/3 genes displayed various expression patterns at selected developmental stages and were induced in the roots by both low and high nitrogen levels. Furthermore, the overexpression of HvNRT2.1 improved the yield related traits in Arabidopsis. Taken together, the data generated in the present study will be useful for genome-wide analyses to determine the precise role of the HvNRT2/3 genes during barley development, with the ultimate goal of improving NUE and crop production.


Assuntos
Proteínas de Transporte de Ânions/genética , Proteínas de Transporte de Ânions/metabolismo , Biologia Computacional/métodos , Hordeum/crescimento & desenvolvimento , Mapeamento Cromossômico , Evolução Molecular , Duplicação Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Hordeum/genética , Hordeum/metabolismo , Família Multigênica , Nitratos/metabolismo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Sequências de Repetição em Tandem
19.
J Food Sci ; 85(5): 1605-1612, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32249421

RESUMO

Lettuce is one of the most popular vegetables, and the market niche of the baby leaf variety is expanding. The manner in which nitrogen (N) is supplied and the available concentration of the micronutrient molybdenum (Mo) affect N metabolism, with reflects on the nutritional quality of that vegetable. Here, two Mo concentrations (0.06 and 0.12 mg/L) and four proportions (%) of nitrate (NO3 - )/ammonium (NH4 + )(100/0, 75/25, 50/50, and 25/75) were supplied to hydroponic baby leaf lettuce floating type to evaluate their effects on plant growth and leaf mineral and NO3 - compositions. Shoot dry mass did not differ among the different treatments, although fresh mass was lower in treatments with larger proportions of NH4 + . Higher leaf concentrations of NO3 - were observed in plants treated with 100% N-NO3 - , but they were still below tolerable limits for human health. The enzyme nitrate reductase was not found to be sensitive to the nitrogen sources or to Mo concentrations. N proportions and Mo concentrations differently affected macro- (C, N, P, K, Ca, Mg, and S) and micronutrients (Cu, Fe, Mn, Mo, and Zn) leaf concentrations. Although treatment with 100% N-NO3 - favored higher mineral concentrations in lettuce leaves, the addition of 25% N-NH4 + allowed fresh mass production with the lowest NO3 - concentrations. As such, and considering the healthy reduction of NO3 - consumption by humans and the maintenance of plant productivity, the 75/25 NO3 - /NH4 + proportion is recommended for the hydroponic cultivation of baby leaf var. Mimosa lettuce. PRACTICAL APPLICATION: We demonstrate a direct link between the constitution of nutrient solution with nitrate accumulation by hydroponic lettuce and indicate the best source of N as well as the concentration of Mn to healthy reduction of NO3 - consumption by humans and the maintenance of plant productivity.


Assuntos
Alface/metabolismo , Molibdênio/metabolismo , Nitratos/análise , Folhas de Planta/química , Compostos de Amônio/análise , Compostos de Amônio/metabolismo , Humanos , Hidroponia , Alface/química , Alface/crescimento & desenvolvimento , Molibdênio/análise , Nitratos/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Valor Nutritivo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Verduras/química , Verduras/crescimento & desenvolvimento , Verduras/metabolismo
20.
J Appl Microbiol ; 129(3): 590-600, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32259336

RESUMO

AIMS: This study was done to obtain denitrifiers that could be used for bioaugmentation in woodchip bioreactors to remove nitrate from agricultural subsurface drainage water. METHODS AND RESULTS: We isolated denitrifiers from four different bioreactors in Minnesota, and characterized the strains by measuring their denitrification rates and analysing their whole genomes. A total of 206 bacteria were isolated from woodchips and thick biofilms (bioslimes) that formed in the bioreactors, 76 of which were able to reduce nitrate at 15°C. Among those, nine potential denitrifying strains were identified, all of which were isolated from the woodchip samples. Although many nitrate-reducing strains were isolated from the bioslime samples, none were categorized as denitrifiers but instead as carrying out dissimilatory nitrate reduction to ammonium. CONCLUSIONS: Among the denitrifiers confirmed by 15 N stable isotope analysis and genome analysis, Cellulomonas cellasea strain WB94 and Microvirgula aerodenitrificans strain BE2.4 appear to be promising for bioreactor bioaugmentation due to their potential for both aerobic and anaerobic denitrification, and the ability of strain WB94 to degrade cellulose. SIGNIFICANCE AND IMPACT OF THE STUDY: Denitrifiers isolated in this study could be useful for bioaugmentation application to enhance nitrate removal in woodchip bioreactors.


Assuntos
Agricultura/métodos , Reatores Biológicos/microbiologia , Desnitrificação , Purificação da Água/métodos , Madeira/microbiologia , Betaproteobacteria/isolamento & purificação , Betaproteobacteria/metabolismo , Biodegradação Ambiental , Cellulomonas/isolamento & purificação , Cellulomonas/metabolismo , Minnesota , Nitratos/isolamento & purificação , Nitratos/metabolismo , Madeira/metabolismo
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