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1.
Int J Mol Sci ; 22(16)2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34445254

RESUMO

Nitrogen forms (nitrate (NO3-) or ammonium (NH4+)) are vital to plant growth and metabolism. In stevia (Stevia rebaudiana), it is important to assess whether nitrogen forms can influence the synthesis of the high-value terpene metabolites-steviol glycosides (SGs), together with the underlying mechanisms. Field and pot experiments were performed where stevia plants were fertilized with either NO3- or NH4+ nutrition to the same level of nitrogen. Physiological measurements suggested that nitrogen forms had no significant impact on biomass and the total nitrogen content of stevia leaves, but NO3--enhanced leaf SGs contents. Transcriptomic analysis identified 397 genes that were differentially expressed (DEGs) between NO3- and NH4+ treatments. Assessment of the DEGs highlighted the responses in secondary metabolism, particularly in terpenoid metabolism, to nitrogen forms. Further examinations of the expression patterns of SGs synthesis-related genes and potential transcription factors suggested that GGPPS and CPS genes, as well as the WRKY and MYB transcription factors, could be driving N form-regulated SG synthesis. We concluded that NO3-, rather than NH4+, can promote leaf SG synthesis via the NO3--MYB/WRKY-GGPPS/CPS module. Our study suggests that insights into the molecular mechanism of how SG synthesis can be affected by nitrogen forms.


Assuntos
Amônia/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glucosídeos/biossíntese , Nitratos/metabolismo , Stevia/metabolismo , Transcrição Genética/efeitos dos fármacos , Diterpenos do Tipo Caurano , Perfilação da Expressão Gênica , Glucosídeos/genética , Nitratos/farmacologia , Stevia/genética
2.
Nat Commun ; 12(1): 4944, 2021 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-34400629

RESUMO

Plants use nitrate, ammonium, and organic nitrogen in the soil as nitrogen sources. Since the elevated CO2 environment predicted for the near future will reduce nitrate utilization by C3 species, ammonium is attracting great interest. However, abundant ammonium nutrition impairs growth, i.e., ammonium toxicity, the primary cause of which remains to be determined. Here, we show that ammonium assimilation by GLUTAMINE SYNTHETASE 2 (GLN2) localized in the plastid rather than ammonium accumulation is a primary cause for toxicity, which challenges the textbook knowledge. With exposure to toxic levels of ammonium, the shoot GLN2 reaction produced an abundance of protons within cells, thereby elevating shoot acidity and stimulating expression of acidic stress-responsive genes. Application of an alkaline ammonia solution to the ammonium medium efficiently alleviated the ammonium toxicity with a concomitant reduction in shoot acidity. Consequently, we conclude that a primary cause of ammonium toxicity is acidic stress.


Assuntos
Compostos de Amônio/metabolismo , Compostos de Amônio/toxicidade , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Glutamato-Amônia Ligase/metabolismo , Plastídeos/metabolismo , Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Glutamato-Amônia Ligase/efeitos dos fármacos , Glutamato-Amônia Ligase/genética , Nitratos/metabolismo , Nitrogênio/metabolismo , Brotos de Planta/metabolismo
3.
Science ; 373(6556): 813-818, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34385401

RESUMO

A Western-style, high-fat diet promotes cardiovascular disease, in part because it is rich in choline, which is converted to trimethylamine (TMA) by the gut microbiota. However, whether diet-induced changes in intestinal physiology can alter the metabolic capacity of the microbiota remains unknown. Using a mouse model of diet-induced obesity, we show that chronic exposure to a high-fat diet escalates Escherichia coli choline catabolism by altering intestinal epithelial physiology. A high-fat diet impaired the bioenergetics of mitochondria in the colonic epithelium to increase the luminal bioavailability of oxygen and nitrate, thereby intensifying respiration-dependent choline catabolism of E. coli In turn, E. coli choline catabolism increased levels of circulating trimethlamine N-oxide, which is a potentially harmful metabolite generated by gut microbiota.


Assuntos
Colo/fisiologia , Dieta Hiperlipídica , Escherichia coli/metabolismo , Mucosa Intestinal/fisiologia , Metilaminas/metabolismo , Animais , Hipóxia Celular , Colina/administração & dosagem , Colina/metabolismo , Colo/citologia , Metabolismo Energético , Células Epiteliais/fisiologia , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Fezes/microbiologia , Microbioma Gastrointestinal , Inflamação , Mucosa Intestinal/metabolismo , Masculino , Metilaminas/sangue , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Nitratos/metabolismo , Obesidade , Consumo de Oxigênio
4.
BMC Plant Biol ; 21(1): 347, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301191

RESUMO

BACKGROUND: Tomato (Solanum lycopersicum) is one of the most important horticultural crops, with a marked preference for nitrate as an inorganic nitrogen source. The molecular mechanisms of nitrate uptake and assimilation are poorly understood in tomato. NIN-like proteins (NLPs) are conserved, plant-specific transcription factors that play crucial roles in nitrate signaling. RESULTS: In this study, genome-wide analysis identified six NLP members in tomato genome. These members were clustered into three clades in a phylogenetic tree. Comparative genomic analysis showed that SlNLP genes exhibited collinear relationships to NLPs in Arabidopsis, canola, maize and rice, and that the expansion of the SlNLP family mainly resulted from segmental duplications in the tomato genome. Tissue-specific expression analysis showed that one of the close homologs of AtNLP6/7, SlNLP3, was strongly expressed in roots during both the seedling and flowering stages, that SlNLP4 and SlNLP6 exhibited preferential expression in stems and leaves and that SlNLP6 was expressed at high levels in fruits. Furthermore, the nitrate uptake in tomato roots and the expression patterns of SlNLP genes were measured under nitrogen deficiency and nitrate resupply conditions. Four SlNLPs, SlNLP1, SlNLP2, SlNLP4 and SlNLP6, were upregulated after nitrogen starvation. And SlNLP1 and SlNLP5 were induced rapidly and temporally by nitrate. CONCLUSIONS: These results provide significant insights into the potential diverse functions of SlNLPs to regulate nitrate uptake.


Assuntos
Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Nitratos/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Transdução de Sinais/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Brassica napus/genética , Brassica napus/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Estudo de Associação Genômica Ampla , Genótipo , Oryza/genética , Oryza/metabolismo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Zea mays/genética , Zea mays/metabolismo
5.
Gene ; 796-797: 145806, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34197950

RESUMO

To sustain high crop yield, a comprehensive understanding of the processes by which plants sense and acquire nutrients is of great importance. For the efficiency of crop fertilizer, it is essential to exploring the the signaling networks that coordinate the usage of nitrogen and phosphorus, the most demanding two mineral nutrients in plants. Here, we found that a protein OsCBL1 (Calcineurin B-like protein 1) is involved in the regulation of nitrogen and phosphorus signaling in rice. The nitrogen element, existing as ammonium or nitrate in the environment, affects nitrate signaling in vivo and root growth. Compared with the wild type, knockdown of OsCBL1 inhibit the growth of rice to the same extent, when nitrogen is deficient or nitrogen is present in the form of ammonium-nitrate mixture. The growth inhibition by OsCBL1-knockdown is more pronounced when nitrogen is present as ammonium. The phosphorus starvation-responsive genes is also regulated by the compound of nitrogen present in vitro and OsCBL1, while the phosphorus content is not affected. These results suggest that OsCBL1 may be involved in the response of rice to nitrogen and phosphorus nutrition in the environment, as well as the regulation of rice growth by environmental nutrition.


Assuntos
Proteínas de Ligação ao Cálcio/fisiologia , Nitratos/metabolismo , Oryza/crescimento & desenvolvimento , Fosfatos/metabolismo , Proteínas de Plantas/fisiologia , Plântula/crescimento & desenvolvimento , Proteínas de Ligação ao Cálcio/genética , Técnicas de Silenciamento de Genes , Oryza/genética , Proteínas de Plantas/genética , Plântula/genética , Transdução de Sinais
6.
Molecules ; 26(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205200

RESUMO

Excessive use of nitrogen fertilizer in intensively managed agriculture has resulted in abundant accumulation of nitrate in soil, which limits agriculture sustainability. How to reduce nitrate content is the key to alleviate secondary soil salinization. However, the microorganisms used in soil remediation cause some problems such as weak efficiency and short survival time. In this study, seaweed polysaccharides were used as stimulant to promote the rapid growth and safer nitrate removal of denitrifying bacteria. Firstly, the growth rate and NO3--N removal capacity of three kinds of denitrifying bacteria, Bacillus subtilis (BS), Pseudomonas stutzeri (PS) and Pseudomonas putida (PP), were compared. The results showed that Bacillus subtilis (BS) had a faster growth rate and stronger nitrate removal ability. We then studied the effects of Enteromorpha linza polysaccharides (EP), carrageenan (CA), and sodium alginate (AL) on growth and denitrification performance of Bacillus subtilis (BS). The results showed that seaweed polysaccharides obviously promoted the growth of Bacillus subtilis (BS), and accelerated the reduction of NO3--N. More importantly, the increased NH4+-N content could avoid excessive loss of nitrogen, and less NO2--N accumulation could avoid toxic effects on plants. This new strategy of using denitrifying bacteria for safely remediating secondary soil salinization has a great significance.


Assuntos
Bactérias/crescimento & desenvolvimento , Nitratos/metabolismo , Polissacarídeos/farmacologia , Alga Marinha/química , Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/metabolismo , Bactérias/metabolismo , Biodegradação Ambiental , Desnitrificação , Pseudomonas putida/crescimento & desenvolvimento , Pseudomonas putida/metabolismo , Pseudomonas stutzeri/crescimento & desenvolvimento , Pseudomonas stutzeri/metabolismo , Solo/química , Microbiologia do Solo
7.
Int J Mol Sci ; 22(14)2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34299235

RESUMO

The allergenic and inflammatory potential of proteins can be enhanced by chemical modification upon exposure to atmospheric or physiological oxidants. The molecular mechanisms and kinetics of such modifications, however, have not yet been fully resolved. We investigated the oligomerization and nitration of the grass pollen allergen Phl p 5 by ozone (O3), nitrogen dioxide (NO2), and peroxynitrite (ONOO-). Within several hours of exposure to atmospherically relevant concentration levels of O3 and NO2, up to 50% of Phl p 5 were converted into protein oligomers, likely by formation of dityrosine cross-links. Assuming that tyrosine residues are the preferential site of nitration, up to 10% of the 12 tyrosine residues per protein monomer were nitrated. For the reaction with peroxynitrite, the largest oligomer mass fractions (up to 50%) were found for equimolar concentrations of peroxynitrite over tyrosine residues. With excess peroxynitrite, the nitration degrees increased up to 40% whereas the oligomer mass fractions decreased to 20%. Our results suggest that protein oligomerization and nitration are competing processes, which is consistent with a two-step mechanism involving a reactive oxygen intermediate (ROI), as observed for other proteins. The modified proteins can promote pro-inflammatory cellular signaling that may contribute to chronic inflammation and allergies in response to air pollution.


Assuntos
Phleum/metabolismo , Proteínas de Plantas/metabolismo , Rinite Alérgica Sazonal/metabolismo , Alérgenos/química , Cinética , Nitratos/metabolismo , Dióxido de Nitrogênio/química , Óxidos de Nitrogênio , Oxidantes , Ozônio/química , Ácido Peroxinitroso/química , Proteínas de Plantas/análise , Poaceae/metabolismo , Pólen/metabolismo , Proteínas/química , Rinite Alérgica Sazonal/fisiopatologia
8.
Nat Commun ; 12(1): 4501, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301958

RESUMO

Nitric oxide (NO) is a short-lived signaling molecule that plays a pivotal role in cardiovascular system. Organic nitrates represent a class of NO-donating drugs for treating coronary artery diseases, acting through the vasodilation of systemic vasculature that often leads to adverse effects. Herein, we design a nitrate-functionalized patch, wherein the nitrate pharmacological functional groups are covalently bound to biodegradable polymers, thus transforming small-molecule drugs into therapeutic biomaterials. When implanted onto the myocardium, the patch releases NO locally through a stepwise biotransformation, and NO generation is remarkably enhanced in infarcted myocardium because of the ischemic microenvironment, which gives rise to mitochondrial-targeted cardioprotection as well as enhanced cardiac repair. The therapeutic efficacy is further confirmed in a clinically relevant porcine model of myocardial infarction. All these results support the translational potential of this functional patch for treating ischemic heart disease by therapeutic mechanisms different from conventional organic nitrate drugs.


Assuntos
Implantes de Medicamento/metabolismo , Infarto do Miocárdio/metabolismo , Nitratos/metabolismo , Óxidos de Nitrogênio/metabolismo , Animais , Cardiotônicos/metabolismo , Cardiotônicos/farmacologia , Modelos Animais de Doenças , Implantes de Medicamento/farmacologia , Coração/efeitos dos fármacos , Coração/fisiopatologia , Ativação de Macrófagos/efeitos dos fármacos , Masculino , Camundongos , Infarto do Miocárdio/mortalidade , Infarto do Miocárdio/prevenção & controle , Isquemia Miocárdica/metabolismo , Isquemia Miocárdica/prevenção & controle , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Células RAW 264.7 , Ratos Sprague-Dawley , Taxa de Sobrevida , Suínos
9.
Nat Microbiol ; 6(9): 1129-1139, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34267357

RESUMO

Nitrate is an abundant nutrient and electron acceptor throughout Earth's biosphere. Virtually all nitrate in nature is produced by the oxidation of nitrite by the nitrite oxidoreductase (NXR) multiprotein complex. NXR is a crucial enzyme in the global biological nitrogen cycle, and is found in nitrite-oxidizing bacteria (including comammox organisms), which generate the bulk of the nitrate in the environment, and in anaerobic ammonium-oxidizing (anammox) bacteria which produce half of the dinitrogen gas in our atmosphere. However, despite its central role in biology and decades of intense study, no structural information on NXR is available. Here, we present a structural and biochemical analysis of the NXR from the anammox bacterium Kuenenia stuttgartiensis, integrating X-ray crystallography, cryo-electron tomography, helical reconstruction cryo-electron microscopy, interaction and reconstitution studies and enzyme kinetics. We find that NXR catalyses both nitrite oxidation and nitrate reduction, and show that in the cell, NXR is arranged in tubules several hundred nanometres long. We reveal the tubule architecture and show that tubule formation is induced by a previously unidentified, haem-containing subunit, NXR-T. The results also reveal unexpected features in the active site of the enzyme, an unusual cofactor coordination in the protein's electron transport chain, and elucidate the electron transfer pathways within the complex.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Oxirredutases/química , Oxirredutases/metabolismo , Bactérias/química , Bactérias/genética , Proteínas de Bactérias/genética , Domínio Catalítico , Microscopia Crioeletrônica , Cristalografia por Raios X , Cinética , Complexos Multiproteicos/química , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Nitratos/metabolismo , Nitritos/metabolismo , Oxirredução , Oxirredutases/genética
10.
Int J Mol Sci ; 22(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207153

RESUMO

Aerobic denitrification is considered as a promising biological method to eliminate the nitrate contaminants in waterbodies. However, the molecular mechanism of this process varies in different functional bacteria. In this study, the nitrogen removal characteristics for a newly isolated aerobic denitrifier Bacillus subtilis JD-014 were investigated, and the potential functional genes involved in the aerobic denitrification process were further screened through transcriptome analysis. JD-014 exhibited efficient denitrification performance when having sodium succinate as the carbon source with the range of nitrate concentration between 50 and 300 mg/L. Following the transcriptome data, most of the up-regulated differentially expressed genes (DEGs) were associated with cell motility, carbohydrate metabolism, and energy metabolism. Moreover, gene nirsir annotated as sulfite reductase was screened out and further identified as a regulator participating in the nitrogen removal process within JD-014. The findings in present study provide meaningful information in terms of a comprehensive understanding of genetic regulation of nitrogen metabolism, especially for Bacillus strains.


Assuntos
Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Regulação Bacteriana da Expressão Gênica , Nitrogênio/metabolismo , Carbono/metabolismo , Biologia Computacional/métodos , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Ontologia Genética , Nitratos/metabolismo , Nitrificação , Reprodutibilidade dos Testes
11.
Int J Mol Sci ; 22(11)2021 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-34072989

RESUMO

Under anaerobic conditions, bacteria may utilize nitrates and nitrites as electron acceptors. Sensitivity to nitrous compounds is achieved via several mechanisms, some of which rely on sensor histidine kinases (HKs). The best studied nitrate- and nitrite-sensing HKs (NSHKs) are NarQ and NarX from Escherichia coli. Here, we review the function of NSHKs, analyze their natural diversity, and describe the available structural information. In particular, we show that around 6000 different NSHK sequences forming several distinct clusters may now be found in genomic databases, comprising mostly the genes from Beta- and Gammaproteobacteria as well as from Bacteroidetes and Chloroflexi, including those from anaerobic ammonia oxidation (annamox) communities. We show that the architecture of NSHKs is mostly conserved, although proteins from Bacteroidetes lack the HAMP and GAF-like domains yet sometimes have PAS. We reconcile the variation of NSHK sequences with atomistic models and pinpoint the structural elements important for signal transduction from the sensor domain to the catalytic module over the transmembrane and cytoplasmic regions spanning more than 200 Å.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias , Histidina Quinase , Proteínas de Membrana , Nitratos/metabolismo , Nitritos/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Histidina Quinase/química , Histidina Quinase/classificação , Histidina Quinase/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Domínios Proteicos
12.
Int J Mol Sci ; 22(9)2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-34066572

RESUMO

The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF) genes, initially characterized as nitrate or peptide transporters in plants, are involved in the transport of a large variety of substrates, including amino acids, nitrate, auxin (IAA), jasmonates (JAs), abscisic acid (ABA) and gibberellins (GAs) and glucosinolates. A total of 169 potential functional NPF genes were excavated in Brassica napus, and they showed diversified expression patterns in 90 different organs or tissues based on transcriptome profile data. The complex time-serial expression changes were found for most functional NPF genes in the development process of leaves, silique walls and seeds, which indicated that the expression of Brassica napus NPF (BnaNPF) genes may respond to altered phytohormone and secondary metabolite content through combining with promoter element enrichment analysis. Furthermore, many BnaNPF genes were detected to respond to vernalization with two different patterns, and 20 BnaNPF genes responded to nitrate deficiency. These results will provide useful information for further investigation of the biological function of BnaNPF genes for growth and development in rapeseed.


Assuntos
Proteínas de Transporte de Ânions/genética , Brassica napus/genética , Brassica napus/fisiologia , Flores/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Nitrogênio/deficiência , Proteínas de Plantas/genética , Sequência de Aminoácidos , Proteínas de Transporte de Ânions/química , Proteínas de Transporte de Ânions/metabolismo , Brassica napus/efeitos dos fármacos , Variações do Número de Cópias de DNA/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Nitratos/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Domínios Proteicos , Especificidade da Espécie , Sintenia/genética
13.
Molecules ; 26(9)2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-34067155

RESUMO

The aim of this study was to evaluate the involvement of nanoparticles prepared from Allium cepa L. as anti-inflammatory agents. In the present study, we identified nanoparticles from Allium cepa L. using the ultracentrifugation exosome purification method. The nanoparticles were referred to as 17,000× g and 200,000× g precipitates, and they contained quercetins, proteins, lipids, and small-sized RNA. The nanoparticles inhibited nitric oxide production from lipopolysaccharide (LPS)-stimulated RAW264 cells without cytotoxic properties. Cellular incorporation was confirmed by laser microscopic observation after PKH26 staining. The inhibition of caveolae-dependent endocytosis and macropinocytosis significantly prevented the incorporation of the nanoparticles but had no effect on the inhibition of nitric oxide in RAW264 cells. Collectively, the identified nanoparticles were capable of inhibiting the LPS response via extracellular mechanisms. Taken together, the way of consuming Allium cepa L. without collapsing the nanoparticles is expected to provide an efficient anti-inflammatory effect.


Assuntos
Endocitose , Espaço Intracelular/metabolismo , Nanopartículas/química , Nitratos/metabolismo , Cebolas/química , Animais , Clatrina/metabolismo , Lipopolissacarídeos , Camundongos , Óxido Nítrico/biossíntese , Quercetina/análise , Células RAW 264.7
14.
Arch Microbiol ; 203(7): 4081-4089, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34052893

RESUMO

Bacillus licheniformis DAS-1 and DAS-2 were found as potent tool for removal/uptake of arsenic [As(V) and As(III)] and reduction [(As(V) to As(III)] of arsenic from the liquid growth medium in our previous studies. Present work gives light on modulation of arsenic remediation (in terms of uptake and reduction) by two selected essential soil nutrients, phosphate (PO4)3- and nitrate (NO3)-. PO43- has structural analogy with arsenate [AsO43-/As(V)] that compete with cell uptake of As(V). It was found that enrichment of 0.75 mM of PO43- had significantly moderated the As(V) toxicity in liquid broth culture by retarding As(V) uptake. Lowering level of PO43- can lead to increase in As(V) removal from medium and vice versa. NO3- has strong oxidant properties which controls As(III) oxidation into As(V) in medium that resulted less toxicity favouring growth of bacteria and also more uptake via phosphate transporters. Hence, accelerated As(III) uptake has shown on enrichment of 0.5 mM of NO3- in medium. All the results of work give evidence that appropriate enrichment of PO43- and NO3- into liquid growth medium, can significantly contribute in alteration of efficiency for arsenic removal/uptake and reduction by bacteria from the medium.


Assuntos
Arsênio , Bacillus licheniformis , Arsênio/metabolismo , Bacillus licheniformis/metabolismo , Biodegradação Ambiental , Nitratos/química , Nitratos/metabolismo , Fosfatos/metabolismo , Solo
15.
Commun Biol ; 4(1): 530, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33953314

RESUMO

A key question in microbial ecology is what the driving forces behind the persistence of large biodiversity in natural environments are. We studied a microbial community with more than 100 different types of species which evolved in a 15-years old bioreactor with benzene as the main carbon and energy source and nitrate as the electron acceptor. Using genome-centric metagenomics plus metatranscriptomics, we demonstrate that most of the community members likely feed on metabolic left-overs or on necromass while only a few of them, from families Rhodocyclaceae and Peptococcaceae, are candidates to degrade benzene. We verify with an additional succession experiment using metabolomics and metabarcoding that these few community members are the actual drivers of benzene degradation. As such, we hypothesize that high species richness is maintained and the complexity of a natural community is stabilized in a controlled environment by the interdependencies between the few benzene degraders and the rest of the community members, ultimately resulting in a food web with different trophic levels.


Assuntos
Bactérias/classificação , Benzeno/metabolismo , Biodegradação Ambiental , Biodiversidade , Metagenoma , Nitratos/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo
16.
J Exp Bot ; 72(15): 5735-5750, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34050740

RESUMO

Upon sensing nitrate, NODULE INCEPTION (NIN)-like protein (NLP) transcription factors alter gene expression to promote nitrate uptake and utilization. Of the nine NLPs in Arabidopsis, the physiological roles of only three NLPs (NLP6-NLP8) have been characterized to date. To evaluate the unique and redundant roles of Arabidopsis NLPs, we assessed the phenotypes of single and higher order nlp mutants. Unlike other nlp single mutants, nlp2 and nlp7 single mutants showed a reduction in shoot fresh weight when grown in the presence of nitrate as the sole nitrogen source, indicating that NLP2, like NLP7, plays a major role in vegetative growth. Interestingly, the growth defect of nlp7 recovered upon the supply of ammonium or glutamine, whereas that of nlp2 did not. Furthermore, complementation assays using chimeric constructs revealed that the coding sequence, but not the promoter region, of NLP genes was responsible for the differences between nlp2 and nlp7 single mutant phenotypes, suggesting differences in protein function. Importantly, nitrate utilization was almost completely abolished in the nlp septuple mutant (nlp2 nlp4 nlp5 nlp6 nlp7 nlp8 nlp9), suggesting that NLPs other than NLP2 and NLP7 also assist in the regulation of nitrate-inducible gene expression and nitrate-dependent promotion of vegetative growth in Arabidopsis.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Nitratos/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
Artigo em Inglês | MEDLINE | ID: mdl-34016249

RESUMO

A novel strain was isolated from grassland soil that has the potential to assimilate ammonium by the reduction of nitrate in the presence of oxygen. Whole genome sequence analysis revealed the presence of an assimilatory cytoplasmic nitrate reductase gene nasA and the assimilatory nitrite reductase genes nirBD which are involved in the sequential reduction of nitrate to nitrite and further to ammonium, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate represents a member of the genus Pseudomonas. The closest phylogenetic neighbours based on 16S rRNA gene sequence analysis are the type strains of Pseudomonas peli (98.17%) and Pseudomonas guineae (98.03%). In contrast, phylogenomic analysis revealed a close relationship to Pseudomonas alcaligenes. Computation of the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) with the closest phylogenetic neighbours of S1-A32-2T revealed genetic differences at the species level, which were further substantiated by differences in several physiological characteristics. On the basis of these results, it was concluded that the soil isolate represents a novel species of the genus Pseudomonas, for which the name Pseudomonas campi sp. nov. (type strain S1-A32-2T=LMG 31521T=DSM 110222T) is proposed.


Assuntos
Pradaria , Filogenia , Pseudomonas/classificação , Microbiologia do Solo , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Genes Bacterianos , Alemanha , Nitratos/metabolismo , Hibridização de Ácido Nucleico , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
18.
J Appl Physiol (1985) ; 131(1): 142-157, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34043471

RESUMO

Dietary nitrate supplementation improves exercise performance by reducing the oxygen cost of exercise and enhancing skeletal muscle function. However, the mechanisms underlying these effects are not well understood. The purpose of this study was to assess changes in skeletal muscle energy metabolism associated with exercise performance in a zebrafish model. Fish were exposed to sodium nitrate (60.7 mg/L, 303.5 mg/L, 606.9 mg/L), or control water, for 21 days and analyzed at intervals (5, 10, 20, 30, 40 cm/s) during a 2-h strenuous exercise test. We measured oxygen consumption during an exercise test and assessed muscle nitrate concentrations, gene expression, and the muscle metabolome before, during, and after exercise. Nitrate exposure reduced the oxygen cost of exercise and increased muscle nitrate concentrations at rest, which were reduced with increasing exercise duration. In skeletal muscle, nitrate treatment upregulated expression of genes central to nutrient sensing (mtor), redox signaling (nrf2a), and muscle differentiation (sox6). In rested muscle, nitrate treatment increased phosphocreatine (P = 0.002), creatine (P = 0.0005), ATP (P = 0.0008), ADP (P = 0.002), and AMP (P = 0.004) compared with rested-control muscle. Following the highest swimming speed, concentration of phosphocreatine (P = 8.0 × 10-5), creatine (P = 6.0 × 10-7), ATP (P = 2.0 × 10-6), ADP (P = 0.0002), and AMP (P = 0.004) decreased compared with rested nitrate muscle. Our data suggest nitrate exposure in zebrafish lowers the oxygen cost of exercise by changing the metabolic programming of muscle prior to exercise and increasing availability of energy-rich metabolites required for exercise.NEW & NOTEWORTHY We show that skeletal muscle nitrate concentration is higher with supplementation at rest and was lower in groups with increasing exercise duration in a zebrafish model. The higher availability of nitrate at rest is associated with upregulation of key nutrient-sensing genes and greater availability of energy-producing metabolites (i.e., ATP, phosphocreatine, glycolytic intermediates). Overall, nitrate supplementation may lower oxygen cost of exercise through improved fuel availability resulting from metabolic programming of muscle prior to exercise.


Assuntos
Nitratos , Peixe-Zebra , Animais , Suplementos Nutricionais , Metaboloma , Músculo Esquelético/metabolismo , Nitratos/metabolismo
19.
Food Chem ; 361: 129997, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34029911

RESUMO

The contribution of free amino acids and thiamine to the production of potent meat aroma compounds in nitrite-reduced, dry-fermented sausages inoculated with a D. hansenii strain was the objective of this study. For this, three different sausage formulations were manufactured; a control and two formulations reduced by half in nitrate and nitrite and one of them inoculated with D. hansenii. Free amino acids, thiamine content and savoury volatile compounds were analysed. Eleven savoury volatile compounds were quantitated. Among them, the most potent compounds above their odour thresholds were 2-methyl-3-furanthiol, 2-acetyl-1-pyrroline, methional, dimethyl trisulfide and methyl-2-methyl-3-furyl disulfide. Their generation was affected by D. hansenii inoculation as shown by the decrease in methional and methyl 2-methyl-3-furyl disulfide content, and the increase of methionol. Nitrate and nitrite reduction did not significantly affect amino acid and thiamine contents.


Assuntos
Aminoácidos/análise , Debaryomyces , Alimentos e Bebidas Fermentados/análise , Produtos da Carne/análise , Odorantes/análise , Aldeídos/análise , Fermentação , Alimentos e Bebidas Fermentados/microbiologia , Produtos da Carne/microbiologia , Nitratos/metabolismo , Nitritos/metabolismo , Tiamina/análise , Fermento Seco
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