Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 110
Filtrar
1.
Food Funct ; 12(20): 10053-10070, 2021 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-34515716

RESUMO

The current study aimed to evaluate the protective activity of peptides isolated from Jinhua ham (JHP) against alcoholic liver disease (ALD) and the mechanisms by which JHP prevents against ALD. The tangential flow filtration (TFF) combined with size exclusion chromatography (SEC) and reversed-phase high performance liquid chromatography (RP-HPLC) were used to isolate the JHP. Then the hepatoprotective activity of peptides was evaluated through experiments in mice. The primary structure of the peptide with the strongest liver protective activity was Lys-Arg-Gln-Lys-Tyr-Asp (KRQKYD) and the peptide was derived from the myosin of Jinhua ham, which were both identified by LC-MS/MS. Furthermore, the mechanism of KRQKYD prevention against ALD was attributed to the fact that KRQKYD increases the abundance of Akkermansia muciniphila in the gut and decreases the abundance of Proteobacteria (especially Escherichia_Shigella). The LPS-mediated liver inflammatory cascade was reduced by protecting the intestinal barrier, increasing the tight connection of intestinal epithelial cells and reducing the level of LPS in the portal venous circulation. KRQKYD could inhibit the production of ROS by upregulating the expression of the NRF2/HO-1 antioxidant defense system and by reducing oxidative stress injury in liver cells. This study can provide a theoretical foundation for the application of JHP in the protection of liver from ALD.

2.
Chemosphere ; 287(Pt 2): 132148, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34509756

RESUMO

Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) is an important process linking nitrogen and carbon cycle. It is recently demonstrated that n-DAMO archaea are able to couple n-DAMO to dissimilatory nitrate reduction to ammonium (DNRA). In this work, a mathematical model is developed to describe DNRA by n-DAMO archaea for the first time. The anabolic and catabolic processes of n-DAMO archaea, n-DAMO bacteria and anaerobic ammonium oxidation (Anammox) bacteria are involved. The different impacts of exogenous and endogenous nitrite on DNRA and n-DAMO microbes are considered. The developed model is calibrated and validated using experimental data collected from a sequencing batch reactor (SBR) and a counter-diffusion membrane biofilm bioreactor (MBfR). The model outputs fit well with the profiles of nitrogen (N) dynamics and biomass changes in both reactors, demonstrating its good predictive ability. The developed model is further used to simulate the counter-diffusion MBfR incorporating n-DAMO and Anammox process to treat sidestream wastewater. The simulated distribution profiles of N removal/production rates by different microbes along biofilm depth reveal that DNRA by n-DAMO archaea plays an important role in N transformation of the integrated n-DAMO and Anammox process. It is further suggested that the counter-diffusion MBfR under the investigated conditions should be operated at proper hydraulic retention times (HRTs) (i.e. 6h and 8h) with exogenous NO2- in the range of 0-10 mg N/L or at HRTs >3h with the absence of exogenous NO2- in order to achieve dischargeable effluent.

3.
Plant J ; 2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34314526

RESUMO

DNA methylation is an important epigenetic mark. In plants, de novo DNA methylation occurs mainly through the RNA-directed DNA methylation (RdDM) pathway. Researchers have previously inferred that a flowering regulator, MULTICOPY SUPPRESSOR OF IRA1 4 (MSI4)/FVE, is involved in non-CG methylation at several RdDM targets, suggesting a role of FVE in RdDM. However, whether and how FVE affects RdDM genome-wide is not known. Here, we report that FVE is required for DNA methylation at thousands of RdDM target regions. In addition, dysfunction of FVE significantly reduces 24-nucleotide siRNA accumulation that is dependent on factors downstream in the RdDM pathway. By using chromatin immunoprecipitation and sequencing (ChIP-seq), we show that FVE directly binds to FVE-dependent 24-nucleotide siRNA cluster regions. Our results also indicate that FVE may function in RdDM by physically interacting with RDM15, a downstream factor in the RdDM pathway. Our study has therefore revealed that FVE, by associating with RDM15, directly regulates DNA methylation and siRNA accumulation at a subset of RdDM targets.

4.
Artigo em Inglês | MEDLINE | ID: mdl-34264497

RESUMO

The respirable dust pollution produced in the cutting process of tunnelling machine during tunnelling process is a serious threat to the health of workers. The key to solve this problem is to build an effective ventilation system in the tunnel. In this paper, experiments were designed and implemented to obtain the temporal-spatial evolution of respirable dust pollution before and after the 3D spiral wind-curtain generator was used for tunnel auxiliary ventilation, and the CFD method was used to supplement and visualize the experimental results. Before the 3D spiral wind-curtain generator was used, the respirable dust gradually diffused from the cutting face to other spaces of the tunnel, and finally presented a stable state with time. After using the 3D spiral wind-curtain generator for auxiliary ventilation, the dust diffusion speed in the tunnel was slower than before, and the dust concentration was lower than before. When adjusting the position of the generator and installing it 20m away from the cutting face, an effective dust control wind-curtain formed within the range of 3.5 ~ 6.5m away from the cutting face. With the increase of time, the dust is stably controlled within the space of 4.5m away from the cutting face, and then pumped away by the exhaust fan, so as to purify the tunnel environment and ensure the tunnel's cleanliness and safety and efficient excavation.

5.
Planta Med ; 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34293804

RESUMO

Flueggea suffruticosa is a traditional Chinese medicine that has been commonly used for the treatment of inflammatory ailments, including rheumatism and lumbago. Suffrutines A and suffrutines B are a pair of novel E,E and Z,E isomeric indolizidine alkaloids isolated from the roots of F. suffruticosa. However, their anti-inflammatory activity has not been reported thus far. The aim of this study was to investigate the inhibitory effect of inflammatory mediators and possible mechanisms of suffrutines A and B in lipopolysaccharide-induced RAW264.7 cells. Results showed that suffrutines A and B could remarkably inhibit the production of nitric oxide, prostaglandin E2, interleukin-6, inducible nitric oxide synthase, and cyclooxygenase-2 in lipopolysaccharide-induced RAW264.7 cells. Further evaluation demonstrated that compared with suffrutines A, suffrutines B could more significantly inhibit the phosphorylation of IKKα/ß, the degradation of IκBα, and the nuclear translocation of the p65 and p52 subunits in the canonical and non-canonical nuclear factor-κB pathways. Therefore, suffrutines B exhibited more potent inhibitory activity on inflammatory mediators than suffrutines A.

6.
Biochem Soc Trans ; 49(3): 1479-1487, 2021 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-34060587

RESUMO

As a subgroup of horticultural crops, vegetable food is a kind of indispensable energy source for human beings, providing necessary nutritional components including vitamins, carbohydrates, dietary fiber, and active substances such as carotenoids and flavonoids. The developmental process of vegetable crops is not only regulated by environmental stimulations, but also manipulated by both genetic and epigenetic modifications. Epigenetic modifications are composed by several regulatory mechanisms, including DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs. Among these modifications, DNA methylation functions in multiple biological pathways ranging from fundamental development to environmental stimulations by mediating transcriptomic alterations, resulting in the activation or silencing of target genes. In recent years, intensive studies have revealed that DNA methylation is essential to fruit development and ripening, indicating that the epigenome of fruit crops could be dynamically modified according to the specific requirements in the commercial production. Firstly, this review will present the mechanisms of DNA methylation, and update the understanding on active DNA demethylation in Arabidopsis thaliana. Secondly, this review will summarize the recent progress on the function of DNA methylation in regulating fruit ripening. Moreover, the possible functions of DNA methylation on controlling the expansion of edible organs, senescence of leafy vegetables, and anthocyanin pigmentation in several important vegetable crops will be discussed. Finally, this review will highlight the intractable issues that need to be resolved in the application of epigenome in vegetable crops, and provide perspectives for the potential challenges in the further studies.

7.
Food Chem ; 364: 130356, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34147870

RESUMO

The present study illustrated modulation of protein aggregation by affecting disulfide/sulfhydryl exchange reactions by adding different concentrations of free thiol represented by reduced-glutathione (GSH) for modulating myofibrillar protein (MP) gel properties at 75 °C or 95 °C. Gel strength and rheological results showed the effects of GSH were dependent on the concentrations (5, 10, 20, 40, and 80 g/kg) and heating temperatures. SEM results showed that the addition of GSH improved the gel microstructure at 95 °C. AFM and DLS results indicated that protein aggregation was also inhibited. At 75 °C, the addition of GSH influenced both MP aggregation and gel properties. Low concentrations (5, 10 g/kg) of GSH promoted aggregation, whereas high concentrations (20, 40, and 80 g/kg) of GSH inhibited this. By analyzing the protein structure and cross-linking pattern changes of MP and MP/GSH composites, a pathway involving GSH influencing MP gel properties was determined.


Assuntos
Proteínas Musculares , Miofibrilas , Dissulfetos , Géis , Glutationa , Temperatura
8.
Cell Biol Toxicol ; 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34170461

RESUMO

Crystalline silica (CS), an airborne particulate, is a major global occupational health hazard. While it is known as an important pathogenic factor in many severe lung diseases, the underlying mechanisms of its toxicity are still unclear. In the present study, we found that intra-tracheal instillation of CS caused rapid emergence of necrotic alveolar macrophages. Cell necrosis was a consequence of the release of cathepsin B in CS-treated macrophages, which caused dysfunction of the mitochondrial membrane. Damage to mitochondria disrupted Na+/K+ ATPase activity in macrophages, leading to intracellular sodium overload and the subsequent cell necrosis. Further studies indicate that CS-induced macrophage necrosis and the subsequent release of mitochondrial DNA could trigger the recruitment of neutrophils in the lung, which was regulated by the TLR9 signaling pathway. In conclusion, our results suggest a novel mechanism whereby CS leads to rapid macrophage necrosis through cathepsin B release, following the leakage of mitochondrial DNA as a key event in the induction of pulmonary neutrophilic inflammation. This study has important implications for the early prevention and treatment of diseases induced by CS.

9.
J BUON ; 26(2): 359-365, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34076980

RESUMO

PURPOSE: The purpose of this study was to uncover the influence of microRNA-188-5p (miRNA-188-5p) on the metastasis of glioma, thus providing a new direction in the early diagnosis and prediction of disease progression. METHODS: MiRNA-188-5p levels in 44 glioma tissues and paracancerous ones were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Its influence on pathological indicators and prognosis in glioma patients was analyzed. In glioma cell lines, regulatory effects of miRNA-188-5p on cell phenotypes were examined by cell counting kit-8 (CCK-8), wound healing and Transwell assay, respectively. Moreover, the interaction between miRNA-188-5p and XRCC5, as well as their involvement in the development of glioma were finally illustrated. RESULTS: MiRNA-188-5p was downregulated in glioma samples. Glioma patients expressing a low level of miRNA-188-5p had a higher rate of distant metastasis and worse prognosis. Overexpression of miRNA-188-5p remarkably attenuated proliferative and migratory abilities of glioma cells. XRCC5 was the downstream gene of miRNA-188-5p, and its level was negatively regulated by miRNA-188-5p. Besides, XRCC5 was upregulated in glioma samples. Moreover, XRCC5 was responsible for the inhibitory effects of miRNA-188-5p on the metastasis of glioma. CONCLUSIONS: MiRNA-188-5p is linked to distant metastasis and prognosis in glioma patients, and it inhibits the proliferative and migratory abilities of glioma cells by binding XRCC5 and then negatively regulating its level.

10.
Meat Sci ; 179: 108527, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33962166

RESUMO

This study investigated the effect of low voltage electrostatic field (LVEF) on the microstructure damage and protein structure changes of prepared beef steak during freezing. The scanning electron microscopy results showed that LVEF-assisted freezing (LVEFF) minimized the gaps in the cross section between muscle fibers induced by freezing and thus improved fiber compactness. Furthermore, LVEFF reduced the length of the enlarged sarcomere, repaired the Z-line fractures, and intensified the dismission of the A band in the air-blast freezing (AF) process. The decreased carbonyl content and increased total sulfhydryl content indicated that LVEFF reduced protein oxidation in the freezing process. In addition, the results of Raman spectroscopy and fluorescence spectroscopy revealed that LVEFF minimized the changes in protein secondary and tertiary structures during freezing. In conclusion, utilization of LVEF in the freezing of prepared beef steak could reduce both the microstructure damage and protein structure changes in the freezing process.


Assuntos
Alimentos Congelados , Produtos da Carne/análise , Eletricidade Estática , Animais , Bovinos , Manipulação de Alimentos/métodos , Congelamento , Masculino , Microscopia Eletrônica de Varredura/veterinária , Fibras Musculares Esqueléticas/ultraestrutura , Sarcômeros
11.
J Hazard Mater ; 412: 125223, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-33951863

RESUMO

Molecular dynamics simulation combined with experimental methods were used to investigate the adsorption and wetting process of 25 lauryl glucoside (APG-12) molecules on coal molecules and in turn study the dust suppression mechanism by APG-12 at the molecular level. Through wetting experiments, our preliminary findings showed that APG-12 does have a certain wetting effect on coal dust. According to density functional theory in molecular dynamics simulations, the electrostatic potential and surface charge of the APG-12 and coal molecular models were analyzed to identify their nucleophilic and electrophilic regions, and illustrate the hydrogen bond adsorption mechanism. The dynamics simulation results showed that APG-12 molecules can be easily adsorbed on the surface of coal molecules and then adsorb water molecules around them under the action of hydrogen bonds. This was consistent with the results of an analysis of the system's radial distribution function and the relative concentration distribution of each component in the Z-axis direction. The results are in good agreement with the experimental results from scanning electron microscopy and energy dispersive spectrometer analysis. These data provide further evidence that APG-12 can clearly improve the wettability and suppression of coal dust, which is of great importance for controlling coal dust pollution.

13.
Genes (Basel) ; 12(4)2021 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-33918349

RESUMO

As essential structural components of ATP-dependent chromatin-remodeling complex, the nucleolus-localized actin-related proteins (ARPs) play critical roles in many biological processes. Among them, ARP4 is identified as an integral subunit of chromatin remodeling complex SWR1, which is conserved in yeast, humans and plants. It was shown that RNAi mediated knock-down of Arabidopsisthaliana ARP4 (AtARP4) could affect plant development, specifically, leading to early flowering. However, so far, little is known about how ARP4 functions in the SWR1 complex in plant. Here, we identified a loss-of-function mutant of AtARP4 with a single nucleotide change from glycine to arginine, which had significantly smaller leaf size. The results from the split luciferase complementation imaging (LCI) and yeast two hybrid (Y2H) assays confirmed its physical interaction with the scaffold and catalytic subunit of SWR1 complex, photoperiod-independent early flowering 1 (PIE1). Furthermore, mutation of AtARP4 caused altered transcription response of hundreds of genes, in which the number of up-regulated differentially expressed genes (DEGs) was much larger than those down-regulated. Although most DEGs in atarp4 are related to plant defense and response to hormones such as salicylic acid, overall, it has less overlapping with other swr1 mutants and the hta9 hta11 double-mutant. In conclusion, our results reveal that AtARP4 is important for plant growth and such an effect is likely attributed to its repression on gene expression, typically at defense-related loci, thus providing some evidence for the coordination of plant growth and defense, while the regulatory patterns and mechanisms are distinctive from other SWR1 complex components.


Assuntos
Actinas/genética , Actinas/metabolismo , Proteínas de Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo , Substituição de Aminoácidos , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Sítios de Ligação , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Humanos , Mutação com Perda de Função , Ligação Proteica , Domínios Proteicos , Fatores de Transcrição/química , Técnicas do Sistema de Duplo-Híbrido
14.
Sci Total Environ ; 783: 147008, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-33872908

RESUMO

The particulate matter (PM) emitted by a trackless rubber-tyred vehicle (TRTV) in coal mines can seriously threaten the health and safety of the exposed workers underground. In this paper, in order to effectively reduce the PM concentration and improve the underground working environment, a combination of numerical simulations and field measurements was adopted to study the migration distribution of the PM emitted by a TRTV at an idle speed for 60 s under different movement conditions, and the dilution effects of the ventilation rate on the PM. The results showed that under different movement conditions, the PM mainly moved along the floor of the roadway, but upward diffusion trends were shown overall, which meant that the chambers are in high-risk areas. Field measurements were then performed under the two conditions to verify the effectiveness of the simulations. Furthermore, the dilution effects of the increased ventilation rate on the PM were analyzed. It was concluded that the optimal dilution ventilation rate under condition 1 was 4600m3/min, and that under condition 2 was 2800m3/min. Accordingly, the driver of the TRTV should try to move forward when entering the chamber.

15.
Hortic Res ; 8(1): 85, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33790255

RESUMO

The conserved histone variant H2A.Z is essential for transcriptional regulation; defense responses; and various biological processes in plants, such as growth, development, and flowering. However, little is known about how H2A.Z affects the developmental process and ripening of tomato fruits. Here, we utilized the CRISPR/Cas9 gene-editing system to generate a sl_hta9 sl_hta11 double-mutant, designated sl_h2a.z, and found that these two mutations led to a significant reduction in the fresh weight of tomato fruits. Subsequent messenger RNA (mRNA)-seq results showed that dysfunction of Sl_H2A.Z has profound effects on the reprogramming of genome-wide gene expression at different developmental stages of tomato fruits, indicating a ripening-dependent correlation between Sl_H2A.Z and gene expression regulation in tomato fruits. In addition, the expression of three genes, SlPSY1, SlPDS, and SlVDE, encoding the key enzymes in the biosynthesis pathway of carotenoids, was significantly upregulated in the later ripening stages, which was consistent with the increased contents of carotenoids in sl_h2a.z double-mutant fruits. Overall, our study reveals a role of Sl_H2A.Z in the regulation of carotenoids and provides a resource for the study of Sl_H2A.Z-dependent gene expression regulation. Hence, our results provide a link between epigenetic regulation via histone variants and fruit development, suggesting a conceptual framework to understand how histone variants regulate tomato fruit quality.

16.
Bioact Mater ; 6(11): 3678-3691, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33898872

RESUMO

The immunosuppressive tumor microenvironment (TME) of cancer strongly hinders the anti-tumor immune responses, thereby resulting in disappointing responses to immunotherapy. Chemoattractive and promotive traits of chemokines exerted on leukocytes have garnered interest in improving the efficiency of immunotherapy by increasing the infiltration of immune cells in the TME. In this study, a folic acid (FA) -modified gene delivery system based on the self-assembly of DOTAP, MPEG-PCL-MPEG, and FA-PEG-PCL-PEG-FA, namely F-PPPD, was developed to deliver plasmids encoding the immunostimulating chemokine CKb11. The delivery of plasmid CKb11 (pCKb11) by F-PPPD nanoparticles resulted in the high secretion of CKb11 from tumor cells, which successfully activated T cells, suppressed the M2 polarization of macrophages, promoted the maturation of dendritic cells (DCs), facilitated the infiltration of natural killer (NK) cells and inhibited the infiltration of immunosuppressive cells in tumor tissues. Administration of F-PPPD/pCKb11 also significantly suppressed the cancer progression. Our study demonstrated a nanotechnology-enabled delivery of pCKb11, that remodeled the immunosuppressive TME, for cancer treatment.

17.
J BUON ; 26(1): 152-158, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33721446

RESUMO

PURPOSE: To explore the influence of nm23-H1 on the proliferation and apoptosis of glioma cells and the mechanism of action. METHODS: The changes in the messenger RNA (mRNA) expression of nm23-H1 were detected via quantitative real-time-polymerase chain reaction (qRT-PCR), and the relative protein expression level of nm23-H1 was determined using immunohistochemistry. The glioma H4 cells were transfected exogenously with nm23-H1 gene (nm23-H1 group) or empty vector (Vector group), and the biological influence of the expression level of nm23-H1 on H4 cells was then assessed through in vitro functional experiments. Besides, the cells transfected with nm23-H1 were incubated with the protein kinase C (PKC) pathway inhibitor Calphostin C, and functional experiments were performed to observe the changes in the proliferation and apoptosis of cells after incubation. RESULTS: According to the immunohistochemistry and qRT-PCR results, the protein and mRNA expression levels of nm23-H1 declined notably in glioma tissues (p<0.01). The cells with up-regulated nm23-H1 expression had substantially weakened proliferation and migration abilities, but exhibited dramatically enhanced apoptosis (p<0.01). The PKC pathway inhibitor considerably potentiated the effects of nm23-H1 protein on the proliferation and apoptosis of H4 cells (p<0.05), and the protein expression level of nm23-H1 rose in the cells treated with the PKC inhibitor (p<0.01). CONCLUSIONS: Compared with normal brain tissues, nm23-H1 is lowly expressed in glioma tissues and affects the expression of PKC to influence the biological behaviors of H4 cells.


Assuntos
Neoplasias Encefálicas/metabolismo , Glioma/metabolismo , Nucleosídeo NM23 Difosfato Quinases/metabolismo , Proteína Quinase C/metabolismo , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Proliferação de Células/fisiologia , Glioma/genética , Glioma/patologia , Humanos , Nucleosídeo NM23 Difosfato Quinases/genética , Transdução de Sinais
18.
J Integr Plant Biol ; 63(4): 772-786, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33615694

RESUMO

Active DNA demethylation is critical for altering DNA methylation patterns and regulating gene expression. The 5-methylcytosine DNA glycosylase/lyase ROS1 initiates a base-excision repair pathway for active DNA demethylation and is required for the prevention of DNA hypermethylation at 1 000s of genomic regions in Arabidopsis. How ROS1 is regulated and targeted to specific genomic regions is not well understood. Here, we report the discovery of an Arabidopsis protein complex that contains ROS1, regulates ROS1 gene expression, and likely targets the ROS1 protein to specific genomic regions. ROS1 physically interacts with a WD40 domain protein (RWD40), which in turn interacts with a methyl-DNA binding protein (RMB1) as well as with a zinc finger and homeobox domain protein (RHD1). RMB1 binds to DNA that is methylated in any sequence context, and this binding is necessary for its function in vivo. Loss-of-function mutations in RWD40, RMB1, or RHD1 cause DNA hypermethylation at several tested genomic regions independently of the known ROS1 regulator IDM1. Because the hypermethylated genomic regions include the DNA methylation monitoring sequence in the ROS1 promoter, plants mutated in RWD40, RMB1, or RHD1 show increased ROS1 expression. Importantly, ROS1 binding to the ROS1 promoter requires RWD40, RMB1, and RHD1, suggesting that this complex dictates ROS1 targeting to this locus. Our results demonstrate that ROS1 forms a protein complex with RWD40, RMB1, and RHD1, and that this novel complex regulates active DNA demethylation at several endogenous loci in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Desmetilação do DNA , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Regiões Promotoras Genéticas/genética , Regiões Promotoras Genéticas/fisiologia , Proteínas Proto-Oncogênicas/genética
19.
Water Res ; 194: 116928, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33618110

RESUMO

ANaerobic MEthanotrophic (ANME) archaea are critical microorganisms mitigating methane emission from anoxic zones. In previous studies, sulfate-dependent anaerobic oxidation of methane (AOM) and nitrate-dependent AOM, performed by different clades of ANME archaea, were detected in marine sediments and freshwater environments, respectively. This study shows that simultaneous sulfate- and nitrate-dependent AOM can be mediated by a clade of ANME archaea, which may occur in estuaries and coastal zones, at the interface of marine and freshwater environments enriched with sulfate and nitrate. Long-term (~1,200 days) performance data of a bioreactor, metagenomic analysis and batch experiments demonstrated that ANME-2d not only conducted AOM coupled to reduction of nitrate to nitrite, but also coupled to the conversion of sulfate to sulfide, in collaboration with sulfate-reducing bacteria (SRB). Sulfide was oxidized back to sulfate by sulfide-oxidizing autotrophic denitrifiers with nitrate or nitrite as electron acceptors, in turn alleviating sulfide accumulation. In addition, dissimilatory nitrate reduction to ammonium performed by ANME-2d was detected, providing substrates to Anammox. Metatranscriptomic analysis revealed significant upregulation of flaB in ANME-2d and pilA in Desulfococcus, which likely resulted in the formation of unique nanonets connecting cells and expanding within the biofilm, and putatively providing structural links between ANME-2d and SRB for electron transfer. Simultaneous nitrate- and sulfate-dependent AOM as observed in this study could be an important link between the carbon, nitrogen and sulfur cycles in natural environments, such as nearshore environments.


Assuntos
Metano , Nitratos , Anaerobiose , Archaea/genética , Carbono , Sedimentos Geológicos , Nitrogênio , Oxirredução , Sulfatos , Enxofre
20.
Environ Sci Technol ; 55(2): 1197-1208, 2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33185425

RESUMO

Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) is critical for mitigating methane emission and returning reactive nitrogen to the atmosphere. The genomes of n-DAMO archaea show that they have the potential to couple anaerobic oxidation of methane to dissimilatory nitrate reduction to ammonium (DNRA). However, physiological details of DNRA for n-DAMO archaea were not reported yet. This work demonstrated n-DAMO archaea coupling the anaerobic oxidation of methane to DNRA, which fueled Anammox in a methane-fed membrane biofilm reactor with nitrate as only electron acceptor. Microelectrode analysis revealed that ammonium accumulated where nitrite built up in the biofilm. Ammonium production and significant upregulation of gene expression for DNRA were detected in suspended n-DAMO culture with nitrite exposure, indicating that nitrite triggered DNRA by n-DAMO archaea. 15N-labeling batch experiments revealed that n-DAMO archaea produced ammonium from nitrate rather than from external nitrite. Localized gradients of nitrite produced by n-DAMO archaea in biofilms induced ammonium production via the DNRA process, which promoted nitrite consumption by Anammox bacteria and in turn helped n-DAMO archaea resist stress from nitrite. As biofilms predominate in various ecosystems, anaerobic oxidation of methane coupled with DNRA could be an important link between the global carbon and nitrogen cycles that should be investigated in future research.


Assuntos
Compostos de Amônio , Anaerobiose , Reatores Biológicos , Desnitrificação , Ecossistema , Metano , Nitratos , Nitritos , Oxirredução
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...