RESUMEN
In Streptomyces rimosus M527, the oxytetracycline (OTC) biosynthetic gene cluster is not expressed under laboratory conditions. In this study a reported-guided mutant selection (RGMS) procedure was used to activate the cluster. The double-reporter plasmid pAGT was constructed in which gusA encoding a ß-glucuronidase and tsr encoding a thiostrepton resistance methyltransferase were placed under the control of the native promoter of oxyA gene (PoxyA ). Plasmid pAGT was introduced and integrated into the chromosome of S. rimosus M527 by conjugation, yielding initial strain M527-pAGT. Subsequently, mutants of M527-pAGT were generated by using ribosome engineering technology. The mutants harboring activated OTC gene cluster were selected based on visual observation of GUS activity and thiostrepton resistance. Finally, mutant M527-pAGT-R7 was selected producing OTC in a concentration of 235.2 mg/L. In this mutant transcriptional levels of oxysr genes especial oxyAsr gene were increased compared to wild-type strain S. rimosus M527. The mutant M527-pAGT-R7 showed antagonistic activities against Gram-negative and Gram-positive strains. All data indicate that the OTC gene cluster was successfully activated using the RGMS method.
Asunto(s)
Oxitetraciclina , Streptomyces rimosus , Streptomyces rimosus/genética , Tioestreptona , Familia de Multigenes , Regiones Promotoras GenéticasRESUMEN
BACKGROUND: Streoptomyces rimosus M527 is a producer of the polyene macrolide rimocidin which shows activity against various plant pathogenic fungi. Notably, the regulatory mechanisms underlying rimocidin biosynthesis are yet to be elucidated. RESULTS: In this study, using domain structure and amino acid alignment and phylogenetic tree construction, rimR2, which located in the rimocidin biosynthetic gene cluster, was first found and identified as a larger ATP-binding regulators of the LuxR family (LAL) subfamily regulator. The rimR2 deletion and complementation assays were conducted to explore its role. Mutant M527-ΔrimR2 lost its ability to produce rimocidin. Complementation of M527-ΔrimR2 restored rimocidin production. The five recombinant strains, M527-ER, M527-KR, M527-21R, M527-57R, and M527-NR, were constructed by overexpressing rimR2 gene using the promoters permE*, kasOp*, SPL21, SPL57, and its native promoter, respectively, to improve rimocidin production. M527-KR, M527-NR, and M527-ER exhibited 81.8%, 68.1%, and 54.5% more rimocidin production, respectively, than the wild-type (WT) strain, while recombinant strains M527-21R and M527-57R exhibited no obvious differences in rimocidin production compared with the WT strain. RT-PCR assays revealed that the transcriptional levels of the rim genes were consistent with the changes in rimocidin production in the recombinant strains. Using electrophoretic mobility shift assays, we confirmed that RimR2 can bind to the promoter regions of rimA and rimC. CONCLUSION: A LAL regulator RimR2 was identified as a positive specific-pathway regulator of rimocidin biosynthesis in M527. RimR2 regulates the rimocidin biosynthesis by influencing the transcriptional levels of rim genes and binding to the promoter regions of rimA and rimC.
Asunto(s)
Polienos , Streptomyces rimosus , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Filogenia , Polienos/metabolismo , Streptomyces rimosus/metabolismoRESUMEN
In this study, we employed a reporter-guided mutation selection (RGMS) strategy to improve the rimocidin production of Streptomyces rimosus M527, which is based on a single-reporter plasmid pAN and atmospheric and room temperature plasma (ARTP). In plasmid pAN, PrimA, a native promoter of the loading module of rimocidin biosynthesis (RimA) was chosen as a target, and the kanamycin resistance gene (neo) under the control of PrimA was chosen as the reporter gene. The integrative plasmid pAN was introduced into the chromosome of S. rimosus M527 by conjugation to yield the initial strain S. rimosus M527-pAN. Subsequently, mutants of M527-pAN were generated by ARTP. 79 mutants were obtained in total, of which 67 mutants showed a higher level of kanamycin resistance (Kanr) than that of the initial strain M527-pAN. The majority of mutants exhibited a slight increase in rimocidin production compared with M527-pAN. Notably, 3 mutants, M527-pAN-S34, S38, and S52, which exhibited highest kanamycin resistance among all Kanr mutants, showed 34%, 52%, and 45% increase in rimocidin production compared with M527-pAN, respectively. Quantitative RT-PCR analysis revealed that the transcriptional levels of neo and rim genes were increased in mutants M527-pAN-S34, S38, and S52 compared with M527-pAN. These results confirmed that the RGMS approach was successful in improving the rimocidin production in S. rimosus M527.
Asunto(s)
Streptomyces rimosus , Mutación , Kanamicina/farmacología , Plásmidos/genéticaRESUMEN
The transposon mutagenesis strategy has been employed to generate random insertion mutants and analyze the correlation between genes and secondary metabolites in the genus Streptomyces. In this study, our primary objective was to identify an unknown gene involved in rimocidin biosynthesis and elucidate its role in rimocidin production in Streptomyces rimosus M527. To achieve this, we established a random mutant library of S. rimosus M527 using a Tn5 transposon-mediated random mutagenesis strategy. Among the 137 isolated mutants, M527-G10 and M527-W5 exhibited the most significant variations in antagonistic activity against the plant pathogenic fungus Fusarium oxysporum f. sp. cucumerinum. Specifically, M527-G10 displayed a 72.93% reduction, while M527-W5 showed a 49.8% increase in rimocidin production compared to the wild-type (WT) strain S. rimosus M527. Subsequently, we employed a plasmid rescue strategy to identify the insertion loci of the transposon in the genomes of mutants M527-G10 and M527-W5, revealing a response regulator transcription factor (rrt) and a hypothetical protein (hyp), respectively. The roles of rrt and hyp in rimocidin biosynthesis were determined through gene deletion, overexpression in the WT strain, and complemented expression in the transposon mutants. Notably, the gene-deletion mutants M527-ΔRRT and M527-ΔHYP exhibited similar behavior in rimocidin production compared to the corresponding transposon mutants M527-G10 and M527-W5, suggesting that transposon insertions in genes rrt and hyp led to alterations in rimocidin production. Furthermore, both gene deletion and overexpression of rrt and hyp had no discernible effects on cell growth. These results reveal that genes rrt and hyp have positive and negative impacts on rimocidin production in S. rimosus M527, respectively.
Asunto(s)
Streptomyces rimosus , Streptomyces , Streptomyces rimosus/genética , Streptomyces rimosus/metabolismo , Streptomyces/genética , Streptomyces/metabolismo , Polienos , PlásmidosRESUMEN
Precursor engineering is an effective strategy for the overproduction of secondary metabolites. The polyene macrolide rimocidin, which is produced by Streptomyces rimosus M527, exhibits a potent activity against a broad range of phytopathogenic fungi. It has been predicted that malonyl-CoA is used as extender units for rimocidin biosynthesis. Based on a systematic analysis of three sets of time-series transcriptome microarray data of S. rimosus M527 fermented in different conditions, the differentially expressed accsr gene that encodes acetyl-CoA carboxylase (ACC) was found. To understand how the formation of rimocidin is being influenced by the expression of the accsr gene and by the concentration of malonyl-CoA, the accsr gene was cloned and over-expressed in the wild-type strain S. rimosus M527 in this study. The recombinant strain S. rimosus M527-ACC harboring the over-expressed accsr gene exhibited better performances based on the enzymatic activity of ACC, intracellular malonyl-CoA concentrations, and rimocidin production compared to S. rimosus M527 throughout the fermentation process. The enzymatic activity of ACC and intracellular concentration of malonyl-CoA of S. rimosus M527-ACC were 1.0- and 1.5-fold higher than those of S. rimosus M527, respectively. Finally, the yield of rimocidin produced by S. rimosus M527-ACC reached 320.7 mg/L, which was 34.0% higher than that of S. rimosus M527. These results confirmed that malonyl-CoA is an important precursor for rimocidin biosynthesis and suggested that an adequate supply of malonyl-CoA caused by accsr gene over-expression led to the improvement in rimocidin production.
Asunto(s)
Malonil Coenzima A , Streptomyces rimosus , Acetil-CoA Carboxilasa/genética , Acetil-CoA Carboxilasa/metabolismo , Malonil Coenzima A/metabolismo , Polienos/metabolismo , Streptomyces rimosus/metabolismoRESUMEN
In this study, first, ß-mannanase gene man derived from Bacillus amyloliquefaciens CGMCC1.857 was cloned and expressed in Bacillus subtilis 168 to generate B. subtilis M1. However, the extracellular ß-mannanase activity of B. subtilis M1 was not very high. To further increase extracellular ß-mannanase extracytoplasmic molecular chaperone, PrsA lipoprotein was tandem expressed with man gene in B. subtilis 168 to yield B. subtilis M2. The secretion of ß-mannanase of B. subtilis M2 was enhanced by 15.4%, compared with the control B. subtilis M1. Subsequently, process optimization strategies were also developed to enhance ß-mannanase production by B. subtilis 168 M2. It was noted that the optimal temperature for ß-mannanase production (25°C) was different from the optimal growth temperature (37°C) for B. subtilis. Based on these findings, a two-stage temperature control strategy was proposed where the bacterial culture was maintained at 37°C for the first 12 h to obtain a high rate of cell growth, followed by lowering the temperature to 25°C to enhance ß-mannanase production. Using this strategy, the extracellular ß-mannanase activity reached 5016 ± 167 U/ml at about 36 h, which was 19.1% greater than the best result obtained using a constant temperature (25°C). The result of this study showed that PrsA lipoprotein overexpression and two-stage temperature control strategy were more efficient for ß-mannanase fermentation in B. subtilis.
Asunto(s)
Bacillus subtilis , beta-Manosidasa , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Fermentación , Humanos , Lipoproteínas/genética , Lipoproteínas/metabolismo , Temperatura , beta-Manosidasa/genética , beta-Manosidasa/metabolismoRESUMEN
The nucleoside antibiotic toyocamycin (TM), which is produced by Streptomyces diastatochromogenes 1628, exhibits potent activity against a broad range of phytopathogenic fungi. TM was synthesized through a multi-step reaction, using guanosine triphosphate (GTP) as precursor. Based on a comparison of proteomics data from S. diastatochromogenes 1628 and rifamycin-resistant mutant 1628-T15 with high yield of TM, we determined that the differentially expressed protein X0NBV6 called ribose-phosphate pyrophosphokinase (RHP), which is a rate-limiting enzyme involved in the de novo biosynthesis of GTP, exhibits a higher expression level in mutant 1628-T15. In this study, to elucidate the relationships between RHP, GTP, and TM production, the gene rhp sd encoding RHP was cloned and overexpressed in S. diastatochromogenes strain 1628. The recombinant strain S. diastatochromogenes 1628-RHP exhibited better performance at the transcriptional level of the rhp sd gene, as well as RHP enzymatic activity, intracellular GTP concentration, and TM production, compared to S. diastatochromogenes 1628. Finally, the yield of TM produced by S. diastatochromogenes 1628-RHP (340.2 mg/L) was 133.3% higher than that produced by S. diastatochromogenes1628. Moreover, the transcriptional level of toy genes involved in TM biosynthesis was enhanced due to the overexpression of the rhp sd gene.
Asunto(s)
Streptomyces , Toyocamicina , Antibacterianos/metabolismo , Guanosina Trifosfato/metabolismo , Streptomyces/genética , Streptomyces/metabolismo , Toyocamicina/metabolismoRESUMEN
The nucleoside antibiotic, toyocamycin (TM) exhibits excellent potent activity against several phytopathogenic fungi. Despite its importance, little is known about key factors regulating TM biosynthesis and morphological differentiation in Streptomyces diastatochromogenes 1628. Based on proteomics data obtained from the analysis between wild-type (WT) S. diastatochromogenes 1628 strain and mutant strain 1628-T62 having a low yield of TM, we observed that the differentially expressed protein, X0P338, which was proposed to be a regulator of the GntR-family, exhibited a higher expression level in S. diastatochromogenes 1628. Therefore, in this study, to explore whether protein X0P338 was involved in morphological differentiation and biosynthesis of secondary metabolites, especially TM, the gene called the gntRsd -encoding protein X0P338 was cloned and overexpressed in WT strain 1628 and mutant strain 1628-T62, respectively. The results indicated that the overexpression of gntRsd enhanced TM production in both strain 1628 (120.6 mg/L vs. 306.6 mg/L) and strain 1628-T62 (15.6 mg/L vs. 258.9 mg/L). Besides, the overexpression of gntRsd had positive and negative effects on morphological differentiation in strain 1628 and strain 1628-T62, respectively. The results also showed opposite effects on tetraene macrolide production during the overexpression of gntRsd in strain 1628 and strain 1628-T62. Moreover, transcription levels of genes involved in morphological differentiation and secondary metabolites production were affected by the overexpression of gntRsd gene, both in strain 1628 and strain 1628-T62. These results confirm that X0P338 as a GntR-type pleiotropic regulator that regulates the morphological differentiation and biosynthesis of secondary metabolites, and especially has a positive effect on TM biosynthesis.
Asunto(s)
Streptomyces , Toyocamicina , Antibacterianos/metabolismo , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Streptomyces/genética , Streptomyces/metabolismo , Toyocamicina/metabolismoRESUMEN
As most of the runoff resulting from snow-ice melt is related to climate change factors in the arid region of northwest China, the risk to water resource systems threatens the socio-economic and ecological environment and is becoming increasingly prevalent. Therefore, we explored the risks of water resource shortages for different periods (2010, 2020, and 2030) in the Aksu River basin (ARB) in the northwest arid region of China by reconstructing a risk model based on the framework proposed by the Intergovernmental Panel on Climate Change (IPCC) with an improved vulnerability (V) module and a more suitable hazard probability in the cost module. The major conclusions are as follows: (1) the simulation of the Community Land Model-Distributed Time Variant Gain Model (CLM-DTVGM) and the Vegetation Interface Processes model (VIP) was suitable for the eco-hydrological processes in the ARB under climate change (i.e., R2 ≥ 0.583; Nash coefficient ≥0.371; and relative mean standard ≤155.727 for CLM-DTVGM; R2 = 0.798 for VIP); (2) the vulnerability of the water resource system in the ARB was medium in 2010, and dropped to a medium-low to non-vulnerable level in 2020 before increasing in 2030 under different Representative Concentration Pathways (RCP) (RCP2.6, RCP4.5, and RCP8.5); and (3) there was a medium-low risk of water resource shortages in the ARB in 2010 (i.e., 0.246), and although the risk of water resource shortages decreased in 2020 due to the increasing water supply from mountainous areas, the risk predicted to increase significantly in 2030, to a medium-high risk level. This study is critical for accurately predicting and understanding the impact of climate change on water resource systems as well as on the drought risk in arid regions.
Asunto(s)
Cambio Climático , Recursos Hídricos , Antagonistas de Receptores de Angiotensina , Inhibidores de la Enzima Convertidora de Angiotensina , China , Medición de Riesgo , RíosRESUMEN
Himalaquinones A-G, seven new anthraquinone-derived metabolites, were obtained from the Himalayan-based Streptomyces sp. PU-MM59. The chemical structures of the new compounds were identified based on cumulative analyses of HRESIMS and NMR spectra. Himalaquinones A-F were determined to be unique anthraquinones that contained unusual C-4a 3-methylbut-3-enoic acid aromatic substitutions, while himalaquinone G was identified as a new 5,6-dihydrodiol-bearing angucyclinone. Comparative bioactivity assessment (antimicrobial, cancer cell line cytotoxicity, impact on 4E-BP1 phosphorylation, and effect on axolotl embryo tail regeneration) revealed cytotoxic landomycin and saquayamycin analogues to inhibit 4E-BP1p and inhibit regeneration. In contrast, himalaquinone G, while also cytotoxic and a regeneration inhibitor, did not affect 4E-BP1p status at the doses tested. As such, this work implicates a unique mechanism for himalaquinone G and possibly other 5,6-dihydrodiol-bearing angucyclinones.
Asunto(s)
Antraquinonas/farmacología , Antineoplásicos/farmacología , Streptomyces/química , Ambystoma mexicanum , Aminoglicósidos/aislamiento & purificación , Aminoglicósidos/farmacología , Animales , Antraquinonas/aislamiento & purificación , Antineoplásicos/aislamiento & purificación , Línea Celular Tumoral , Humanos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Pakistán , Microbiología del SueloRESUMEN
China has begun a rapid move towards Sponge City implementation, which will include widespread installation of various Low Impact Development (LID) stormwater infrastructure. Ambitious goals have been set for all Sponge Cities, including a target capture rate of 80-85% of annual precipitation in Beijing. However, there has so far been limited investigation into whether these goals are obtainable at the catchment scale given the physical restrictions of the existing urban landscape. This paper demonstrates the use of long-term continuous hydrologic modelling to evaluate the potential of meeting rainfall capture goals over a long time period for a case study area in Beijing. Detailed land cover classification derived from satellite imagery aided in the parameterization of a SWMM (Stormwater Management Model) model representing a 133â¯km2 urban study area. The calibrated and validated model demonstrated satisfactory agreement between computed and observed runoff for a variety of precipitation events ranging from 10 to 207â¯mm. A synthetic high resolution rainfall time series was generated from historic daily observations then used as input to run the model continuously for a 35 year period. Feasible LID model scenarios based on varying degrees of implementation of rain gardens, permeable pavements and green roofs were compared in terms of their potential volume capture of annual rainfall. Modelling results demonstrated that the conversion of 30% of roof area to green roof, 10% of green areas to rain gardens and 35% of paved areas to permeable pavement could increase the baseline volume capture ratio from 59.9% to 82.2%, indicating that Sponge City goals can be met within the case study area with realistic levels of LID implementation. This study provides a decision-making basis for future planning in the study area.
Asunto(s)
Hidrología , Lluvia , Beijing , China , Ciudades , Movimientos del AguaRESUMEN
BACKGROUND: Soy protein isolate (SPI) has promising applications in various food products because of its excellent functional properties and nutritional quality. The structural and emulsifying properties of covalently modified SPI by (-)-epigallocatechin-3-gallate (EGCG) were investigated. RESULTS: SPI was covalently modified by EGCG under alkaline conditions. SDS-PAGE analysis revealed that EGCG modification caused crosslinking of SPI proteins. Circular dichroism spectra demonstrated that the secondary structure of SPI proteins was changed by EGCG modification. In addition, the modifications resulted in the perturbation of the tertiary structure of SPI as evidenced by intrinsic fluorescence spectra and surface hydrophobicity measurements. Oil-in-water emulsions of modified SPI had smaller droplet sizes and better creaming stability compared to those from unmodified SPI. CONCLUSION: The covalent modification by EGCG improved the emulsifying property of SPI. This study therefore provided an innovative approach for improving the emulsifying properties of proteins. © 2018 Society of Chemical Industry.
Asunto(s)
Proteínas de Soja/química , Catequina/análogos & derivados , Catequina/química , Dicroismo Circular , Emulsiones/química , Interacciones Hidrofóbicas e Hidrofílicas , Conformación Proteica en Hélice alfa , Proteínas de Soja/aislamiento & purificaciónRESUMEN
This experiment was to study the constituents of the roots of Viburnum setigerum through various column chromatographic techniques. Thirteen compounds were obtained and their structures were identified using chemical and spectroscopic methods as (7αH, 8'αH)-4, 4', 8α-trihydroxy-3, 3', 9-trimethoxy-7, 9'-epoxylignan (1), (7αH, 8'αH)-4, 4', 8α, 9-tetrahydroxy-3, 3'-dimethoxy-7, 9'-epoxylignan (2), alashinol G (3), alashinol F (4), (-)-secoisolariciresinol (5), (7R, 7'R, 8R, 8'S)-3, 3'-dimethoxy-7, 7'-epoxylignane -4, 4', 9, 9'-tetraol (6), (7αH, 8αH, 8'ßH)-4, 4', 7'α, 9-tetrahydroxy-3, 3'-dimethoxy-7, 9'-epoxylignan (7), loganin (8), dihydroquercetin (9), protocatechuic acid (10), 4-hydroxy-3-methoxy-benzoic acid (11), adoxoside (12), and catechin (13). Compound 1 was a new compound. Compounds 3-7 and 11 were reported from the genus Viburnum for the first time. All compounds were separated from this plant for the first time.
Asunto(s)
Viburnum , Lignanos , Estructura Molecular , Extractos Vegetales , Raíces de PlantasRESUMEN
A 9-year manipulative experiment with nitrogen (N) and water addition, simulating increasing N deposition and changing precipitation regime, was conducted to investigate the bioavailability of trace elements, iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in soil, and their uptake by plants under the two environmental change factors in a semi-arid grassland of Inner Mongolia. We measured concentrations of trace elements in soil and in foliage of five common herbaceous species including 3 forbs and 2 grasses. In addition, bioaccumulation factors (BAF, the ratio of the chemical concentration in the organism and the chemical concentration in the growth substrate) and foliar Fe:Mn ratio in each plant was calculated. Our results showed that soil available Fe, Mn and Cu concentrations increased under N addition and were negatively correlated with both soil pH and cation exchange capacity. Water addition partly counteracted the positive effects of N addition on available trace element concentrations in the soil. Foliar Mn, Cu and Zn concentrations increased but Fe concentration decreased with N addition, resulting in foliar elemental imbalances among Fe and other selected trace elements. Water addition alleviated the effect of N addition. Forbs are more likely to suffer from Mn toxicity and Fe deficiency than grass species, indicating more sensitivity to changing elemental bioavailability in soil. Our results suggested that soil acidification due to N deposition may accelerate trace element cycling and lead to elemental imbalance in soil-plant systems of semi-arid grasslands and these impacts of N deposition on semi-arid grasslands were affected by water addition. These findings indicate an important role for soil trace elements in maintaining ecosystem functions associated with atmospheric N deposition and changing precipitation regimes in the future.
Asunto(s)
Nitrógeno/metabolismo , Poaceae/metabolismo , Oligoelementos/metabolismo , Agua/metabolismo , China , Cobre/metabolismo , Pradera , Hierro/metabolismo , Manganeso/metabolismo , Suelo/química , Zinc/metabolismoRESUMEN
Water pollution has been a significant issue in the Huai River Basin (HRB) of China since the late 1970s. In July and December 2013, two field investigations were carried out at 10 sites along the main streams of the basin. The monitoring indices contained both physicochemical variables and the structure and composition of phytoplankton communities. The correlations between communities and physicochemical variables were analyzed using cluster analysis and redundancy analysis. Moreover, water quality was evaluated using the comprehensive nutrition state index (TLI) and Shannon-Wiener diversity index (H). Results indicated that more phytoplankton species were present in December than in July, but total density was less in December. Phytoplankton communities in the midstream of the Shaying River were affected by the same physicochemical factors throughout the year, but ammonia nitrogen and total phosphorus had the greatest influence on these sites in July and December, respectively. The water pollution status of the sampling sites was much greater in the Shaying River midstream than at other sites. TLI was more suitable than H for assessing water quality in the study area. These results provide valuable information for policy makers and stakeholders in water quality assessment, water ecosystem restoration, and sustainable basin management in the HRB.
Asunto(s)
Fitoplancton/clasificación , Plantas/clasificación , Ríos/química , Contaminantes Químicos del Agua/análisis , Biodiversidad , China , Ecosistema , Fósforo/análisis , Fósforo/metabolismo , Fitoplancton/crecimiento & desarrollo , Fitoplancton/aislamiento & purificación , Fitoplancton/metabolismo , Desarrollo de la Planta , Plantas/metabolismo , Contaminantes Químicos del Agua/metabolismo , Contaminación del Agua/análisis , Calidad del AguaRESUMEN
Impact assessment of sluice regulation on water quality is one of the crucial tasks in the present river management. However, research difficulties remain because of insufficient in situ data and numerous influencing factors in aquatic environments. The Huaidian Sluice, the main control sluice of the Shaying River, China, was selected for this study. Three field experimental programs were designed and carried out to analyze spatial and temporal variations in water quality parameters under various sluice regulation conditions and to explore the impacts of regulation mechanisms on water quality. Monitoring data were used to simulate water quality under different scenarios by the water quality analysis simulation program (WASP). Results demonstrate that the influences of sluice regulation on permanganate index (CODMn) and ammonia nitrogen (NH4-N) concentrations (indicators of water quality) were complex and nonlinear and presented different trends of increase or decrease from different regulation modes. Gate openings of different widths and different flow rates affected CODMn and NH4-N concentrations differently. Monitoring results and numerical simulation results indicate that the sluice opening should be small. Flow discharge through the sluice should be greater than 10 m(3) s and less than 60 m(3) s to maintain low CODMn concentrations, and discharge should be low (e.g., 14 m(3) s) to maintain low NH4-N concentrations. This research provides an experimental basis for further research on the construction of water quality models and for the development of reasonable regulations on water quality and quantity.
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Monitoreo del Ambiente/métodos , Ríos/química , Contaminación Química del Agua/análisis , Calidad del Agua , China , Modelos Teóricos , Contaminación Química del Agua/legislación & jurisprudenciaRESUMEN
Hepatitis B is the most common serious liver infection in the world. To date, there is still no complete cure for chronic hepatitis B. Natural caffeic acid analogues possess prominent antiviral activity, especially anti-hepatitis B virus (HBV) and anti-human immunodeficiency virus effects. Cichoric acid is a caffeic acid derivative from Cichorium intybus. In the study, the anti-hepatitis B property of cichoric acid was evaluated by the D-galactosamine (D-GalN)-induced normal human HL-7702 hepatocyte injury model, the duck hepatitis B virus (DHBV)-infected duck fetal hepatocytes and the HBV-transfected cell line HepG2.2.15 cells, respectively. The results showed that cichoric acid attenuated significantly D-GalN-induced HL-7702 hepatocyte injury at 10-100 µg/mL and produced a maximum protection rate of 56.26%. Moreover, cichoric acid at 1-100 µg/mL inhibited markedly DHBV DNA replication in infected duck fetal hepatocytes. Also, cichoric acid at 10-100 µg/mL reduced significantly the hepatitis B surface and envelope antigen levels in HepG2.2.15 cells and produced the maximum inhibition rates of 79.94% and 76.41%, respectively. Meanwhile, test compound at 50-100 µg/mL inhibited markedly HBV DNA replication. In conclusion, this study verifies the anti-hepatitis B effect of cichoric acid from Cichorium intybus leaves. In addition, cichoric acid could be used to design the antiviral agents.
Asunto(s)
Ácidos Cafeicos/farmacocinética , Cichorium intybus/química , Virus de la Hepatitis B del Pato/efectos de los fármacos , Hepatocitos/efectos de los fármacos , Sustancias Protectoras/farmacología , Succinatos/farmacocinética , Animales , Ácidos Cafeicos/aislamiento & purificación , Supervivencia Celular/efectos de los fármacos , Citoprotección/efectos de los fármacos , ADN Viral/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Patos , Galactosamina/farmacología , Células Hep G2 , Antígenos de Superficie de la Hepatitis B/metabolismo , Virus de la Hepatitis B del Pato/genética , Virus de la Hepatitis B del Pato/crecimiento & desarrollo , Hepatocitos/virología , Humanos , Estructura Molecular , Hojas de la Planta/química , Sustancias Protectoras/aislamiento & purificación , Succinatos/aislamiento & purificación , Replicación Viral/efectos de los fármacosRESUMEN
Topsoil removal, among other restoration measures, has been recognized as one of the most successful methods to restore biodiversity and ecosystem functioning in European grasslands. However, knowledge about how removal as well as other restoration methods influence interactions between plant and microbial communities is very limited. The aims of the current study were to understand the impact of topsoil removal on plant-microorganism interactions and on soil nitrogen (N) mineralization, as one example of ecosystem functioning. We examined how three different grassland restoration methods, namely 'Harvest only', 'Topsoil removal' and 'Topsoil removal + Propagules (plant seed addition)', affected i) the interactions between plants and soil microorganisms, ii) soil microbial community assembly processes, and iii) soil N mineralization. We compared the outcome of these three restoration methods to initial degraded and target semi-natural grasslands in the Canton of Zurich, Switzerland. We were able to show that 'Topsoil removal' and 'Topsoil removal + Propagules', but not 'Harvest only', reduced the soil total N pool and available N concentration, but increased soil N mineralization and strengthened the plant-microorganism interactions. Microbial community assembly processes shifted towards more deterministic after both topsoil removal treatments. These shifts could be attributed to an increase in dispersal limitation and selection due to stronger interactions between plants and soil microorganisms. The negative relationship between soil N mineralization and microbial community stochasticity indicated that microbial assembly processes, to some extent, can be incorporated into model predictions of soil functions. Overall, the results suggest that topsoil removal may change the microbial assembly processes and thus the functioning of grassland ecosystems by enhancing the interaction between plants and soil microorganisms.
RESUMEN
Soil salinity is one of the adversity stresses plants face, and antioxidant defense mechanisms play an essential role in plant resistance. We investigated the effects of exogenous calcium on the antioxidant defense system in peanut seedling roots that are under salt stress by using indices including the transcriptome and absolute quantitative metabolome of flavonoids. Under salt stress conditions, the antioxidant defense capacity of enzymatic systems was weakened and the antioxidant capacity of the linked AsA-GSH cycle was effectively inhibited. In contrast, the ascorbate biosynthesis pathway and its upstream glycolysis metabolism pathway became active, which stimulated shikimate biosynthesis and the downstream phenylpropanoid metabolism pathway, resulting in an increased accumulation of flavonoids, which, as one of the antioxidants in the non-enzymatic system, provide hydroxyl radicals to scavenge the excess reactive oxygen species and maintain the plant's vital activities. However, the addition of exogenous calcium caused changes in the antioxidant defense system in the peanut root system. The activity of antioxidant enzymes and the antioxidant capacity of the AsA-GSH cycle were enhanced. Therefore, glycolysis and phenylpropanoid metabolism do not exert antioxidant function, and flavonoids were no longer synthesized. In addition, antioxidant enzymes and the AsA-GSH cycle showed a trade-off relationship with sugars and flavonoids.
RESUMEN
Both droughts and tropical cyclones (TCs) are among the world's most widespread natural disasters. This paper is concentrated on the effects of TCs on the links between meteorological droughts (MDs) and agricultural droughts (ADs). Specifically, changes in characteristics of drought events and variations in propagation features of matched MD and AD event pairs are quantified by using the renowned three-dimensional connected components algorithm; both alleviation and exacerbation effects of TCs are evaluated; and the Spearman's correlation is employed to identify potential contributors to exacerbated droughts after TCs. The results show that TCs exhibit more pronounced and widespread alleviation effects on MD events compared to AD events. >98 % of small-scale drought events are terminated by TCs, leading to 65 % reduction in the total area of MD events smaller than 50,000 km2 and 32 % reduction in AD events of the same scale. In the meantime, TCs can reshape the spatiotemporal links between MDs and ADs by reducing the overall propagation rate from 77 % to 40 % and ameliorating the characteristics of drought event pairs with higher propagation efficiency, by >40 %. After TCs, over 55 % of drought exacerbations in TC-affected regions occur first in the vicinity of the residual large-scale AD events. This occurrence is partially associated with the reduction in moisture exports from these residual droughts downwind to the interior of TC-affected regions, a process potentially facilitated by the TC-induced temperature cooling. The in-depth evaluation of this paper presents useful information for better drought preparation and mitigation under TCs.