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1.
J Agric Food Chem ; 67(39): 10813-10822, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31490069

RESUMO

Traditional seed pretreatment methods cause secondary pollution for the application of various chemicals. This study investigated the effect of dielectric barrier discharge (DBD) cold plasma on seedling growth. Effects of plasma-activated tap water (PATW) and plasma-activated seeds (PAS) were compared for germination rates, seedling height, dry weight, and chlorophyll content. Results show that compared with controls these growth parameters were all increased by more than 50%. The yields and contributions of hydrogen peroxide, nitrate, nitrite, and ammonium were quantified. Hydrogen peroxide and nitrate have an important role in seedling growth. By etching, the seed epidermis free radicals can reduce the apparent contact angle and increase the water absorption of the seeds. In addition to the low cost of PATW and PAS compared with commercial fertilizers, DBD does not involve any chemical addition. Thus, both PATW and PAS can be an alternative for improvement of agricultural production.


Assuntos
Produção Agrícola/métodos , Ervilhas/efeitos dos fármacos , Gases em Plasma/farmacologia , Sementes/crescimento & desenvolvimento , Compostos de Amônio/metabolismo , Clorofila/metabolismo , Produção Agrícola/instrumentação , Germinação/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Nitratos/metabolismo , Ervilhas/química , Ervilhas/crescimento & desenvolvimento , Ervilhas/metabolismo , Gases em Plasma/química , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/química , Sementes/efeitos dos fármacos , Sementes/metabolismo , Água/química
2.
J Sci Food Agric ; 99(14): 6608-6619, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31347167

RESUMO

BACKGROUND: Understanding plant responses to light quantity in indoor horticultural systems is important for optimising lettuce growth and metabolism as well as energy utilisation efficiency. Light intensity and photoperiod sufficient for normal plant growth parameters might be not efficient for nitrate assimilation. Therefore, this study explored and compared the effects of different light intensities (100-500 µmol m-2 s-1 ) and photoperiods (12-24 h) on the growth and nitrate assimilation in red and green leaf lettuce (Lactuca sativa L.). RESULTS: For efficient nitrate assimilation, 300-400 µmol m-2 s-1 photosynthetic photon flux density (PPFD) and 16-18 h photoperiod is necessary for red and green lettuces. The insufficient light quantity resulted in reduced growth and remarkable increase in nitrate and nitrite contents in both cultivars. Short photoperiods, similarly to low PPFD, growth parameters, chlorophyll indices and nitrate assimilation indices showed the shortage of photosynthetic products for normal plant physiological processes. Short photoperiods had the least pronounced effect on nitrate and nitrite contents in lettuce leaves. CONCLUSION: Light intensity was superior compared to photoperiods for efficient nitrate assimilation in both lettuce cultivars. Under short photoperiods, similarly to low intensity, growth parameters, chlorophyll index and nitrate assimilation indices showed a shortage of photosynthetic products for normal physiological processes. The free amino acid concentration increased, but it was not efficiently incorporated in proteins, as their level in lettuce was lower compared to those for moderate photoperiods. © 2019 Society of Chemical Industry.


Assuntos
Alface/metabolismo , Alface/efeitos da radiação , Nitratos/metabolismo , Clorofila/análise , Clorofila/metabolismo , Cor , Alface/química , Alface/crescimento & desenvolvimento , Luz , Nitratos/análise , Nitritos/análise , Nitritos/metabolismo , Fotoperíodo , Fotossíntese , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação
3.
Bioresour Technol ; 291: 121836, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344632

RESUMO

The aim of this work was to study the biotreatment of mixed wastewaters collected from two points of MnO2 industry by Chlorella vulgaris. Their growth rates in four mixed wastewaters with mass ratio of wastewater 1#:2# of 20:1, 50:1, 100:1, and 200:1 were characterized, and the lag phase was shortened with increase of nitrate concentrations. The N, P, and metal removal kinetics were quantified each other day to evaluate the bio-treatment efficiencies of high-nitrate wastewaters from MnO2 industry. 84.68% and 98% of N, P has been removed. The Ca, Zn, Mn, and Si in mixed wastewaters was removed with maximum removal efficiencies of 97.91%, 99.37%, 99.44%, and 81.68%, respectively. The compositions of Chlorella vulgaris cultured in mixed wastewaters, including proteins, lipids, ash contents, and carbohydrates, were investigated in detail. The optimum HHV of Chlorella vulgaris about 18 MJ/Kg presented a potential to decrease the cost of algal biofuel.


Assuntos
Chlorella vulgaris/metabolismo , Compostos de Manganês/metabolismo , Nitratos/metabolismo , Óxidos/metabolismo , Águas Residuárias/química , Óxidos de Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/métodos
4.
Gene ; 711: 143950, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31255736

RESUMO

The marine dinoflagellate Alexandrium minutum is known to produce saxitoxins that cause paralytic shellfish poisoning in human worldwide through consumption of the contaminated shellfish mollusks. Despite numerous studies on the growth physiology and saxitoxin production of this species, the knowledge on the molecular basis of nutrient uptakes in relation to toxin production in this species is limited. In this study, relative expressions of the high-affinity transporter genes of nitrate, ammonium, and phosphate (AmNrt2, AmAmt1 and AmPiPT1) and the assimilation genes, nitrate reductase (AmNas), glutamine synthase (AmGSIII) and carbamoyl phosphate synthase (AmCPSII) from A. minutum were studied in batch clonal culture condition with two nitrogen sources (nitrate: NO3- or ammonium: NH4+) under different N:P ratios (high-P: N:P of 14 and 16, and low-P: N:P of 155). The expression of AmAmt1 was suppressed in excess NH4+-grown condition but was not observed in AmNrt2 and AmNas. Expressions of AmAmt1, AmNrt2, AmNas, AmGSIII, AmCPSII, and AmPiPT1 were high in P-deficient condition, showing that A. minutum is likely to take up nutrients for growth under P-stress condition. Conversely, relative expression of AmCPSII was incongruent with cell growth, but was well correlated with toxin quota, suggesting that the gene might involve in arginine metabolism and related toxin production pathway. The expression of AmGSIII is found coincided with higher toxin production and is believed to involve in mechanism to detoxify the cells from excess ammonium stress. The gene regulation observed in this study has provided better insights into the ecophysiology of A. minutum in relation to its adaptive strategies in unfavorable environments.


Assuntos
Técnicas de Cultura Celular por Lotes/métodos , Dinoflagelados/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Compostos de Amônio/metabolismo , Dinoflagelados/metabolismo , Regulação da Expressão Gênica , Nitratos/metabolismo , Fosfatos/metabolismo , Saxitoxina/genética , Estresse Fisiológico
5.
Plant Mol Biol ; 101(1-2): 183-202, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31286324

RESUMO

KEY MESSAGE: Isoforms of 2-OGDH E1 subunit are not functionally redundant in plant growth and development of A. thaliana. The tricarboxylic acid cycle enzyme 2-oxoglutarate dehydrogenase (2-OGDH) converts 2-oxoglutarate (2-OG) to succinyl-CoA concomitant with the reduction of NAD+. 2-OGDH has an essential role in plant metabolism, being both a limiting step during mitochondrial respiration as well as a key player in carbon-nitrogen interactions. In Arabidopsis thaliana two genes encode for E1 subunit of 2-OGDH but the physiological roles of each isoform remain unknown. Thus, in the present study we isolated Arabidopsis T-DNA insertion knockout mutant lines for each of the genes encoding the E1 subunit of 2-OGDH enzyme. All mutant plants exhibited substantial reduction in both respiration and CO2 assimilation rates. Furthermore, mutant lines exhibited reduced levels of chlorophylls and nitrate, increased levels of sucrose, malate and fumarate and minor changes in total protein and starch levels in leaves. Despite the similar metabolic phenotypes for the two E1 isoforms the reduction in the expression of each gene culminated in different responses in terms of plant growth and seed production indicating distinct roles for each isoform. Collectively, our results demonstrated the importance of the E1 subunit of 2-OGDH in both autotrophic and heterotrophic tissues and suggest that the two E1 isoforms are not functionally redundant in terms of plant growth in A. thaliana.


Assuntos
Arabidopsis/enzimologia , Carbono/metabolismo , Complexo Cetoglutarato Desidrogenase/metabolismo , Nitrogênio/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Complexo Cetoglutarato Desidrogenase/genética , Mitocôndrias/enzimologia , Mutagênese Insercional , Nitratos/metabolismo , Fenótipo , Filogenia , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Isoformas de Proteínas , Subunidades Proteicas , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Sementes/enzimologia , Sementes/genética , Sementes/crescimento & desenvolvimento
6.
Bioresour Technol ; 291: 121854, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31357041

RESUMO

Two strains, Enterobacter sp. Z1 and Klebsiella sp. Z2, were exhibited great capacities for heterotrophic nitrification-aerobic denitrification (HNAD) and intracellular phosphate accumulation. Strikingly, the co-cultured strains enhanced the removal efficiency of total nitrogen and phosphate, with removal efficiencies of ammonia, nitrate, nitrite and soluble phosphate of 99.64%, 99.85%, 96.94% and 66.7% respectively. Furthermore, high removal efficiencies from wastewaters with high concentrations of ammonia (over 1000 mg/L) were achieved by inoculation with the co-strains, which left residual ammonia of less than 1 mg/L within 10 h. To elucidate the mechanism of HNAD in co-strains, quantitative PCR was carried out to examine the expression levels of hydroxylamine oxidase (Hao), nitrate reductase (NapA and NarG), nitrite reductase (NirS) and polyphosphate kinase (Ppk), and the results showed that the napA2, narG and ppk genes in the strains were significantly upregulated under the co-cultured conditions and provided an explanation for the nitrogen and phosphate removal.


Assuntos
Enterobacter/metabolismo , Klebsiella/metabolismo , Nitrogênio/metabolismo , Fosfatos/metabolismo , Amônia/metabolismo , Desnitrificação , Processos Heterotróficos , Nitrato Redutase/metabolismo , Nitratos/metabolismo , Nitrificação , Nitrito Redutases/metabolismo , Nitritos/metabolismo , Oxirredutases/metabolismo , Águas Residuárias
7.
Plant Physiol Biochem ; 141: 154-163, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31163342

RESUMO

Different nitrogen (N) sources have been reported to significantly affect the photosynthesis (Pn) and its attributes. However, molybdenum (Mo) induced effects on photosynthetic efficacy of winter wheat under different N sources have not been investigated. A hydroponic study was carried out comprising of two winter wheat cultivars '97003' and '97014' as Mo-efficient and Mo-inefficient, respectively to underpin the effects of Mo supply (0 and 1 µM) on photosynthetic efficacy of winter wheat under different N sources (NO3̶, NH4NO3 or NH4+). The results revealed that Mo-induced increases in dry weight, gas exchange parameters, chlorophyll contents, NR activities, NO3̶ assimilation, total N contents and transcripts of TaNR and TaNRT1.1 genes under different N sources followed the trend of NH4NO3 > NO3̶ > NH4+, suggesting that Mo has more complementary effects to nitrate nutrition than sole ammonium. Interestingly, under Mo-deprivation environments, cultivar '97003' recorded more pronounced alterations in Mo-dependent parameters than '97014' cultivar. Moreover, Mo application significantly improved the chlorophyll contents and chloroplast configuration in all N sources showing that Mo has a key role in chlorophyll biosynthesis and chloroplast integrity. The results also highlighted that Mo-induced enhancements in total N contents and photosynthetic characteristics followed the same order as NH4NO3 > NO3- > NH4+, suggesting that Mo might affect Pn through N metabolism. In crux, our study findings imply that Mo supply increased Pn not only through chlorophyll synthesis and chloroplast configuration but also by N uptake and assimilation which may represent a strategy of Mo fertilizer to strengthen the photosynthetic machinery.


Assuntos
Compostos de Amônio/metabolismo , Molibdênio/farmacologia , Nitrogênio/metabolismo , Fotossíntese/efeitos dos fármacos , Triticum/fisiologia , Clorofila/metabolismo , Cloroplastos/metabolismo , Fertilizantes , Hidroponia , Microscopia Eletrônica de Transmissão , Nitratos/metabolismo , Proteínas de Plantas/metabolismo , Triticum/efeitos dos fármacos
8.
Cell Mol Life Sci ; 76(19): 3753-3764, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31161283

RESUMO

Nitrogen (N) is one of the most important essential macro-elements for plant growth and development, and nitrate represents the most abundant inorganic form of N in soils. The nitrate uptake and assimilation processes are finely tuned according to the available nitrate in the surroundings as well as by the internal finely coordinated signaling pathways. The NIN-like proteins (NLPs) harbor both RWP-RK, and Phox and Bem1 (PB1) domains, and they belong to the well-characterized plant-specific RWP-RK transcription factor gene family. NLPs are known to be involved in the nitrate signaling pathway by activating downstream target genes, and thus they are implicated in the primary nitrate response in the nucleus via their RWP-RK domains. The PB1 domain is a ubiquitous protein-protein interaction domain and it comprises another regulatory layer for NLPs via the protein interactions within NLPs or with other essential components. Recently, Ca2+-Ca2+ sensor protein kinase-NLP signaling cascades have been identified and they allow NLPs to have central roles in mediating the nitrate signaling pathway. NLPs play essential roles in many aspects of plant growth and development via the finely tuned nitrate signaling pathway. Furthermore, recent studies have highlighted the emerging roles played by NLPs in the N starvation response, nodule formation in legumes, N and P interactions, and root cap release in higher plants. In this review, we consider recent advances in the identification, evolution, molecular characteristics, and functions of the NLP gene family in plant growth and development.


Assuntos
Nitratos/metabolismo , Proteínas de Plantas/fisiologia , Fatores de Transcrição/fisiologia , Evolução Biológica , Nitrogênio/metabolismo , Fosfatos/metabolismo , Desenvolvimento Vegetal , Proteínas de Plantas/química , Proteínas de Plantas/classificação , Nodulação , Plantas/metabolismo , Transdução de Sinais , Fatores de Transcrição/química , Fatores de Transcrição/classificação
9.
Mar Pollut Bull ; 142: 603-612, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31232347

RESUMO

Dual isotope nitrate (NO3-) analysis was performed on the western coast of Guangdong Province to investigate seasonal changes in the main nitrate sources and their biogeochemical processing, which are due to the rapid development of the local economy. In the nearshore area, significant seasonal variations of nitrate sources occurred. The dominant nitrate sources, originating from manure and sewage, suggested that the nitrate along the west coast of Guangdong Province was mainly influenced by local cities despite the westward flow of diluted Pearl River water. In the offshore area, the nitrate loss in the upper and mid water during both two seasons mainly caused by phytoplankton assimilation, whereas coupled nitrification-denitrification could be responsible for the nitrate loss in the bottom waters during summer. Our results suggest that, with the rapid development of local economy, the nitrate sources in the coastal area have shifted to manure and sewage from the local cities.


Assuntos
Nitratos/análise , Poluentes Químicos da Água/análise , China , Desnitrificação , Monitoramento Ambiental/métodos , Fertilizantes , Esterco , Nitratos/metabolismo , Nitrificação , Isótopos de Nitrogênio/análise , Fitoplâncton/metabolismo , Estações do Ano , Água do Mar/análise , Água do Mar/química , Esgotos/análise
10.
J Agric Food Chem ; 67(24): 6736-6747, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31184154

RESUMO

Nitrogen is essential for plant growth and crop productivity; however, nitrogen use efficiency (NUE) decreases with increasing N supply, resulting in a waste of resources. Molecular mechanisms underlying low-nitrogen (LN)-mediated enhancement of NUE are not clear. We used high-NUE Brassica napus genotype H (Xiangyou 15), low-NUE B. napus genotype L (814), and Arabidopsis mutant aux1 to elucidate the mechanism underlying the changes in NUE under different rates of N fertilizer application. NUE of B. napus increased under LN, which enhanced N uptake ability by regulating root system architecture and plasma membrane H+-ATPase activity; AUX1 was involved in this process. Additionally, BnNRT1.5 was upregulated and BnNRT1.8 was downregulated under LN, whereby more N was transferred to the shoot through enhanced N transport. Observed changes in photosynthesis under LN were associated with N assimilation efficiency. Our study provides new insights into the mechanisms of plant adaptation to the environment.


Assuntos
Arabidopsis/metabolismo , Brassica napus/metabolismo , Nitratos/metabolismo , Nitrogênio/metabolismo , Arabidopsis/genética , Transporte Biológico , Brassica napus/genética , Fertilizantes/análise , Regulação da Expressão Gênica de Plantas , Nitrogênio/análise , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo
11.
J Agric Food Chem ; 67(26): 7205-7222, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31244197

RESUMO

Nitrate and nitrite ions are used as food additives to inhibit the growth of microorganisms in cured and processed meats. Vegetables contain significant quantities of nitrate and nitrite. Actually, the vast majority of consumed nitrate and nitrite comes from natural vegetables and fruits rather than food additives. For years, the cancer risks of these two ions have been discussed, since they potentially convert into the carcinogenic nitrosamines. However, recently, these two ions have been considered essential nutrients which promote nitric oxide production and consequently help cardiovascular health. It seems that the role of these two ions in our diet is important now from a different point of view. In this review, the nitrate and nitrite contents of food products from different countries are displayed globally in order to reinterpret the risks/benefits of our consumption quotations. This review article is based on Science Citation Index (SCI) articles reported between 2008 and 2018.


Assuntos
Nitratos/análise , Nitritos/análise , Animais , Aditivos Alimentares/análise , Aditivos Alimentares/metabolismo , Humanos , Carne/análise , Nitratos/metabolismo , Nitritos/metabolismo , Medição de Risco , Verduras/química
12.
BMC Plant Biol ; 19(1): 225, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31146677

RESUMO

BACKGROUND: Suboptimal root zone temperature (RZT) causes a remarkable reduction in growth of horticultural crops during winter cultivation under greenhouse production. However, limited information is available on the effects of suboptimal RZT on nitrogen (N) metabolism in cucumber seedlings. The aim of this study is to investigate the effects of 24-Epibrassinolide (EBR) on nitrate and ammonium flux rate, N metabolism, and transcript levels of NRT1 family genes under suboptimal RZT in cucumber seedlings. RESULTS: Suboptimal RZT (LT) negatively affected on cucumber growth and proportionately decreased EBR contents, bleeding rate, root activity, enzyme activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT), nitrate (NO3-) influx rate, ammonium (NH4+) efflux rate, and transcript levels of nitrate transporter (NRT1) encoding genes. However, exogenous EBR reduced the harmful effects of suboptimal RZT and increased endogenous EBR contents, bleeding rate, root activity, enzyme activities of NR, NiR, GS, and GOGAT, NH4+ and NO3- flux rates and contents, and N accumulation. EBR-treated seedlings also upregulated the transcript levels of nitrate transporters CsNRT1.1, CsNRT1.2A, CsNRT1.2B, CsNRT1.2C, CsNRT1.3, CsNRT1.4A, CsNRT1.5B, CsNRT1.5C, CsNRT1.9, and CsNRT1.10, and downregulated CsNRT1.5A and CsNRT1.8. LT treatment upregulated the expression level of CsNRT1.5A, while exogenous BZR application downregulated the expression level of NRT1 genes. CONCLUSION: These results indicate that exogenous application of EBR alleviated the harmful effects of suboptimal RZT through changes in N metabolism, NH4+ and NO3- flux rates, and NRT1 gene expression, leading to improved cucumber seedlings growth. Our study provides the first evidence of the role of EBR in the response to suboptimal RZT in cucumber, and can be used to improve vegetable production.


Assuntos
Compostos de Amônio/metabolismo , Brassinosteroides/metabolismo , Cucumis sativus/genética , Nitratos/metabolismo , Proteínas de Plantas/genética , Esteroides Heterocíclicos/metabolismo , Transcrição Genética , Cucumis sativus/metabolismo , Família Multigênica , Nitrogênio/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Temperatura Ambiente
13.
Life Sci ; 230: 188-196, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31150686

RESUMO

AIMS: Hyperoxia has beneficial metabolic effects in type 2 diabetes. However, hyperoxia exacerbates already existing oxidative stress in type 2 diabetes. Nitrate, a nitric oxide donor, is an effective new treatment in type 2 diabetes and also has antioxidant properties. The aim of this study was to determine whether nitrate administration can attenuate hyperoxia-induced oxidative stress in obese type 2 diabetic rats. MAIN METHODS: Fifty-six male Wistar rats (190-210 g) were divided into 8 groups: Controls (non-treated, nitrate-treated, O2-treated, and nitrate + O2-treated) and diabetes (non-treated, nitrate-treated, O2-treated, and nitrate + O2-treated). Diabetes was induced using high-fat diet and low-dose of streptozotocin (30 mg/kg). Rats in intervention groups, were exposed to 95% oxygen and consumed sodium nitrate (100 mg/L) in drinking water. Serum fasting glucose, oxidized (GSSG) and reduced (GSH) glutathiones, total oxidant status (TOS), catalase and superoxide dismutase (SOD) activities, and total antioxidant capacity (TAC) were measured after intervention. Oxidative stress index (OSI) was calculated as TOS/TAC ratio. KEY FINDINGS: Diabetic rats had increased oxidative stress and hyperoxia exacerbated it. In O2-diabetic rats, nitrate decreased GSSG (102.7 ±â€¯2.1 vs. 236.0 ±â€¯20.1 µM, P < 0.001), TOS (67.7 ±â€¯7.3 vs. 104 ±â€¯3.8 µM, P < 0.001), and OSI (0.44 ±â€¯0.04 vs. 0.91 ±â€¯0.07, P < 0.001) and increased catalase (2.8 ±â€¯0.13 vs. 1.8 ±â€¯0.21 KU/L, P = 0.014), SOD (53.4 ±â€¯1.5 vs. 38.4 ±â€¯1.2 U/mL, P < 0.001), GSH (43.7 ±â€¯1.4 vs. 17.8 ±â€¯0.5 mM, P = 0.003), TAC (152.5 ±â€¯1.9 vs. 116.7 ±â€¯5.0 mM, P < 0.001), and GSH/GSSG ratio (0.43 ±â€¯0.01 vs. 0.08 ±â€¯0.01, P = 0.005). Nitrate also potentiated effects of hyperoxia on decreasing fasting glucose. SIGNIFICANCE: Our results showed that dietary nitrate attenuates hyperoxia-induced oxidative stress in type 2 diabetic rats.


Assuntos
Nitratos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Glicemia/análise , Catalase/análise , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/metabolismo , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais , Glucose/metabolismo , Glutationa/análise , Hiperóxia/tratamento farmacológico , Hiperóxia/metabolismo , Masculino , Nitratos/metabolismo , Obesidade/complicações , Obesidade/metabolismo , Ratos , Ratos Wistar , Superóxido Dismutase/análise
14.
Environ Sci Pollut Res Int ; 26(20): 20610-20618, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31104244

RESUMO

The present study was designed to investigate the protective role of dietary supplementation of Spirulina platensis (SP) against cytotoxic and genotoxic effects of lead nitrate in Clarias gariepinus. Four groups of fishes were used: first group as control which fed on basal diet, second group fed on basal diet and exposed to (1 mg/L of lead nitrate), third group fed on diet containing 0.25% SP and exposed to (1 mg/L of lead nitrate), and fourth group fed on diet containing 0.5%SP and exposed to (1 mg/L of lead nitrate). Fish samples were taken at 2nd and 4th week of exposure. The hematological indices of lead nitrate-exposed group were decreased significantly compared to the control group at 2nd and 4th week of exposure. Lead nitrate caused a significant increase in the percentage of poikilocytosis, micronuclei, and apoptotic cells as well as comet tail length and olive tail moment compared with the control group at 2nd and 4th week of exposure. The highest level of damage was found on 4th week of exposure with all parameters. Dietary inclusion of SP ameliorated these cytotoxic and genetic changes, as well as this amelioration was concentration and time dependent. Consequently, the present study proposed that the addition of SP to the fish diet can be used as a promising protective agent to oppose cytotoxic and genotoxic effects of lead nitrate in aquaculture. Graphical abstract.


Assuntos
Peixes-Gato/metabolismo , Chumbo/toxicidade , Nitratos/toxicidade , Substâncias Protetoras/farmacologia , Spirulina/fisiologia , Poluentes Químicos da Água/toxicidade , Ração Animal/análise , Animais , Biomarcadores/sangue , Peixes-Gato/sangue , Peixes-Gato/genética , Dano ao DNA/efeitos dos fármacos , Suplementos Nutricionais , Chumbo/metabolismo , Nitratos/metabolismo , Substâncias Protetoras/análise , Poluentes Químicos da Água/metabolismo
15.
Chemosphere ; 228: 721-734, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31071559

RESUMO

Nitrate (NO3-) pollution is a serious problem worldwide. Identification of NO3- sources and transformation processes in aquifers is a key step in effectively controlling and mitigating NO3- contamination. In this study, hydrochemical, microbial, and dual isotopic approaches were integrated to elucidate the sources and processes influencing NO3- contamination in the Pearl River Delta, China. The results showed a severe NO3- contamination, with 75% of the samples having NO3--N concentrations above the WHO standard of 10 mg L-1. The δ15NNO3- and δ18ONO3- values and a multivariate statistical analysis of hydrochemical data both revealed that manure and sewage were mainly responsible for NO3- contamination. Biological indicators further demonstrated that, manure and sewage had greater impacts on groundwater quality during the rainy season than during the dry season. Based on the significant relationships of δ15NNO3- and δ18ONO3- with the logarithmic NO3- concentration (Ln(NO3-)), denitrification was confirmed to occur in the discharge zone during the rainy season. Proteobacteria, Bacteroidetes, and Planctomycetes were identified as the dominant phyla, and Dechloromonas, Flavobacterium, and Nitrospira were dominant among the denitrifying bacteria in groundwater. The abundance of denitrifying bacteria had significant positive correlations with δ15NNO3- and NO2--N during the rainy season, further confirming the occurrence of denitrification during the rainy season. This study showed that dual isotope techniques combined with microbial data can be a powerful tool for identifying the sources and microbial processes affecting NO3- in groundwater. Moreover, the results can provide useful insights for environmental managers to verify groundwater pollution and better apply remediation solutions.


Assuntos
Água Subterrânea/química , Água Subterrânea/microbiologia , Nitratos/análise , Poluentes Químicos da Água/química , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , China , Desnitrificação , Monitoramento Ambiental/métodos , Água Subterrânea/análise , Esterco , Nitratos/química , Nitratos/metabolismo , Isótopos de Nitrogênio/análise , Chuva , Estações do Ano , Esgotos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo , Qualidade da Água
16.
Bull Environ Contam Toxicol ; 103(2): 280-285, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31069404

RESUMO

Acorus calamus L., a semiaquatic plant with a high capacity to remove nitrogen and phosphorus from polluted water, is a potential candidate plant for use in the restoration of eutrophic aquatic ecosystems. However, it is not clear how microcystins (MCs), commonly found in eutrophic water, influence plant growth since the effects of MCs are likely to be dose and species dependent. The present study aimed to investigate the regulation of nitrogen metabolism, a key metabolic process related to plant growth, in the leaves of A. calamus L. exposed to microcystin-leucine-arginine (MC-LR) (1.0-29.8 µg/L). Nitrate (NO3-) uptake, assimilation and transformation was stimulated in the leaves of A. calamus L. when exposed to 1.0 µg/L MC-LR through the elevation of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamic-pyruvic transaminase (GPT), and glutamic-oxaloacetic transaminase (GOT) activity. Conversely, MC-LR inhibited nitrogen metabolism by decreasing NO3- uptake and the activities of enzymes related to nitrogen metabolism following exposure to MC-LR (9.9-29.8 µg/L) for 30 days, while, ammonium nitrogen (NH4+) content and glutamate dehydrogenase (GDH) activity increased significantly (p < 0.05, LSD test), when compared with the control group. Chronic exposure to MC-LR (9.9-29.8 µg/L) negatively influenced nitrogen metabolism in A. calamus L. leaves, which suggested that it may not be a suitable candidate species for use in the restoration of eutrophic aquatic ecosystems containing MC-LR at concentrations ≥ 9.9 µg/L.


Assuntos
Acorus/metabolismo , Microcistinas/toxicidade , Nitrogênio/metabolismo , Folhas de Planta/metabolismo , Poluentes Químicos da Água/toxicidade , Acorus/efeitos dos fármacos , Acorus/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Eutrofização , Modelos Teóricos , Nitratos/metabolismo , Fósforo/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento
17.
Environ Pollut ; 251: 659-667, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31108299

RESUMO

Tetrabromobisphenol A (TBBPA) and copper (Cu) are the main pollutants at e-waste recycling sites and the effects of their biotoxicity on microorganisms have drawn extensive attention. Nitrate-based bioremediation has been applied to organic pollutant-contaminated sediments since nitrate is a favorable electron acceptor for microbes. However, the effects of TBBPA and Cu on nitrogen (N)-cycling microorganisms and bioremediation in co-contaminated sediments remain unclear. Thus, our study examined the effects of TBBPA and Cu with/without nitrate addition on the TBBPA biodegradation efficiencies, microbial activities, and N functional genes. It was found the biodegradation efficiencies of TBBPA were improved by the nitrate addition from 34.7% to 59.3% and from 22.6% to 42.8% in the TBBPA and TBBPA-Cu contaminated groups, respectively. The inhibitions of the catalase activity increased with the nitrate addition because of the anaerobic respiration of the microorganisms. In addition, the potential denitrification rate exhibited an increasing trend from 6.46 to 8.23 mg-N kg-1 dry sediment day-1 during the period of 15-90 days after adding nitrate to the co-contaminated group, whereas the potential nitrification rate exhibited an opposite trend and decreased from 4.47 to 3.19 mg-N kg-1 dry sediment day-1. The denitrification gene abundances of the N-cycling genes were 107-108 orders of magnitude higher and significantly increased in the nitrate addition groups. The amoA gene abundances were lower than the denitrification gene abundances and were 105-106 orders of magnitude in the same groups. Moreover, the interaction types of the pollutants on the gene abundances were changed from synergistic to antagonistic as nitrate addition. Our study emphasized the gap of knowledge on nitrate addition affecting N-cycling microbes in the combined pollutants exposure sediments, and will be helpful for further bioremediation in different contaminated scenarios.


Assuntos
Cobre/metabolismo , Nitratos/metabolismo , Ciclo do Nitrogênio , Bifenil Polibromatos/metabolismo , Rios , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Resíduo Eletrônico , Genes Microbianos , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Ciclo do Nitrogênio/genética , Rios/química , Rios/microbiologia
18.
Plant Sci ; 283: 23-31, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31128693

RESUMO

The rice nitrate and di/tripeptide transporter (NPF) gene family plays an indispensable role in nitrogen transport and plant growth. In this study, 18 alternatively spliced OsNPF genes with 36 different forms of mRNAs were identified, and two of these, namely OsNPF7.1 and OsNPF7.4, showed opposite expression patterns in axillary buds under different nitrogen concentrations. Our results indicate that the expression levels of OsNPF7.1 and OsNPF7.4 determine the axillary bud outgrowth, especially for the second bud, and subsequently influence the tiller number in rice. The overexpression of either of the variants of OsNPF7.1 or the knockout of OsNPF7.4 increased the seedling biomass as well as the tiller number, filled grain number, and grain yield in rice. However, the RNAi-mediated silencing of OsNPF7.1 or the overexpression of either of the variants of OsNPF7.4 had an opposite effect. The overexpression of OsNPF7.1 or OsNPF7.4 could improve the uptake of nitrate, but the OsNPF7.4-overexpressing plants had lower biomass. It is possible that excessive nitrate in the OsNPF7.4-overexpressing plants led to the accumulation of amino acids in the leaf sheath, which inhibited seedling biomass. In addition, the reduced reutilization of nitrate in the seedlings also limited the plant biomass. However, the moderate increase in nitrate and amino acid concentrations in the OsNPF7.1-overexpressing plants could promote seedling biomass and enhance grain yield. In conclusion, our data suggest that different members in the NPF family have different roles in rice, and this study suggests an alternative way to modify rice architecture and enhance grain yield by regulating the expression of OsNPF7.1 and OsNPF7.4.


Assuntos
Grão Comestível/crescimento & desenvolvimento , Oryza/genética , Proteínas de Plantas/genética , Aminoácidos/metabolismo , Regulação da Expressão Gênica de Plantas , Técnicas de Silenciamento de Genes , Genes de Plantas/genética , Nitratos/metabolismo , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia
19.
Sci Total Environ ; 659: 442-450, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31096374

RESUMO

Recently it has been shown that Candidatus 'Methanoperedens nitroreducens', an anaerobic methanotrophic archaea (ANME), can reduce nitrate to nitrite using electrons derived from anaerobic oxidation of methane. In this study, the growth kinetics of 'M. nitroreducens' enriched in a laboratory reactor were studied. In the experimental concentration range (up to 16 mg CH4 L-1), anaerobic oxidation of methane by 'M. nitroreducens' was found to comply with first order kinetic model with a rate constant of 0.019 ±â€¯0.006 h-1 and a biomass-specific rate constant of 0.04-0.14 L h-1 g-1VSS. Meanwhile, the nitrate reduction to nitrite was well described by the Monod-type kinetic model with an affinity constant for nitrate of 2.1 ±â€¯0.4 mg N L-1, which is slightly higher than, but comparable to, that of most known denitrifying bacteria. This is the first time that the growth kinetics of 'M. nitroreducens' have been experimentally studied. The applicability of the kinetic model reported herein to this organism or similar organisms in natural or engineering systems requires further investigation.


Assuntos
Metano/metabolismo , Methanosarcinales/crescimento & desenvolvimento , Nitratos/metabolismo , Methanosarcinales/metabolismo , Oxirredução
20.
Environ Pollut ; 250: 863-872, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31085472

RESUMO

Microaerobic and hypoxic methane oxidation coupled to denitrification (MAME-D and HYME-D) occur in stabilized landfills with leachate recirculation when biological denitrification is limited by lack of organics. To evaluate nitrate denitrification efficiency and culture MAME-D/HYME-D involved bacteria, a leach bed bioreactor semi-continuous experiment was conducted for 60 days in 5 runs, under nitrate concentrations ranging of 20 mg/L-55 mg/L, wherein 5% sterile leachate was added during runs 4 and 5. Although the HYME-D system demonstrated high denitrification efficiency (74.93%) and nitrate removal rate reached 2.62 mmol N/(L⋅d), the MAME-D system exhibited a denitrification efficiency of almost 100% and nitrate removal rate of 4.37 mmol N/(L⋅d). The addition of sterile leachate increased the nitrate removal rate in both systems, but caused the decrease of methane consumption in HYME-D. A stable isotope batch experiment was carried out to investigate the metabolic products by monitoring the 13CO2 and 15N2O production. The production of organic intermediates such as citrate, lactic acid, acetate, and propionic acid were also observed, which exhibited a higher yield in HYME-D. Variations in the microbial communities were analyzed during the semi-continuous experiment. MAME-D was mainly conducted by the association of type Ⅰ methanotroph Methylomonas and the methylotrophic denitrifier Methylotenera. Methane fermentation processed by Methylomonas under hypoxic conditions produced more complex organic intermediates and increased the diversity of related heterotrophic denitrifiers. The addition of sterile real leachate, resulting in increase of COD/N, influenced the microbial community of HYME-D system significantly.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação , Metano/análise , Methylocystaceae/metabolismo , Methylomonas/metabolismo , Nitratos/análise , Instalações de Eliminação de Resíduos , Aerobiose , Anaerobiose , Isótopos de Carbono/análise , Processos Heterotróficos , Sequenciamento de Nucleotídeos em Larga Escala , Metano/metabolismo , Microbiota , Nitratos/metabolismo , Isótopos de Nitrogênio/análise , Oxirredução
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