Letteratura scientifica selezionata sul tema "Degradation metabolites"
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Articoli di riviste sul tema "Degradation metabolites"
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Xia, Chaoran, Qiyuan Tian, Lingyu Kong, Xiaoqian Sun, Jingjing Shi, Xiaoqun Zeng e Daodong Pan. "Metabolomics Analysis for Nitrite Degradation by the Metabolites of Limosilactobacillus fermentum RC4". Foods 11, n. 7 (30 marzo 2022): 1009. http://dx.doi.org/10.3390/foods11071009.
Testo completoAbstract (sommario):
Nitrite (NIT), a commonly used food additive, especially in pickled and cured vegetables and meat products, might cause acute and chronic diseases. Fermentation with lactic acid bacteria (LAB) is an effective method for degrading NIT and improving the flavor of pickled and cured foods. In this study, Limosilactobacillus fermentum (L. fermentum) RC4 with a high NIT degradation ability was found to degrade NIT in a new manner when compared with reported enzymatic and acid degradation, namely, metabolite degradation during fermentation in MRS broth, which shows a synergistic effect with acid to increase NIT degradation. Liquid chromatography–mass spectrometry analysis identified 134 significantly different metabolites, of which 11 metabolites of L. fermentum RC4, namely, γ-aminobutyric acid (GABA), isocitric acid, D-glucose, 3-methylthiopropionic acid (MTP), N-formyl-L-methionine, dimethyl sulfone (MSM), D-ribose, mesaconate, trans-aconitic acid, L-lysine, and carnosine, showed significant NIT degradation effects compared with the control group (MRS broth). Verification experiments showed that adding the above 11 metabolites to 100 mg/L NIT and incubating for 24 h resulted in NIT degradation rates of 5.07%, 4.41%, 6.08%, 16.93%, 5.28%, 2.41%, 0.93%, 18.93%, 12.25%, 6.42%, and 3.21%, respectively. Among these, three metabolites, namely, mesaconate, MTP, and trans-aconitic acid, showed efficient NIT degradation abilities that might be related to the degradation mechanism involving decarboxylation reactions. This is the first systematic study of NIT degradation by LAB, resulting in the identification of a new metabolite degradation pathway and three efficient NIT degradation metabolites.
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Shen, C. F., J. A. Hawari, G. Ampleman, S. Thiboutot e S. R. Guiot. "Origin ofp-cresol in the anaerobic degradation of trinitrotoluene". Canadian Journal of Microbiology 46, n. 2 (1 febbraio 2000): 119–24. http://dx.doi.org/10.1139/w99-124.
Testo completoAbstract (sommario):
p-Cresol was repeatedly detected as a trace metabolite in anaerobic slurry reactors treating 2,4,6-trinitrotoluene (TNT)-contaminated soils. This study shows that p-cresol was not a metabolite of the anaerobic degradation of TNT, by using a combination of analytical techniques and13C-labelled TNT. Instead, p-cresol, an intermediate in the degradation pathway of some amino acids, was shown to be inhibited by TNT and its metabolites. The range and persistence of inhibition to p-cresol microbial degradation decreased with the level of amino-substitution of the derivatives. This explains why p-cresol accumulated within the TNT-treating anaerobic bioslurry, as it could not be further biodegraded in the presence of TNT. Key words: p-cresol, bioremediation, trinitrotoluene, inhibition, metabolites.
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Carone, F. A., M. A. Stetler-Stevenson, V. May, A. LaBarbera e G. Flouret. "Differences between in vitro and in vivo degradation of LHRH by rat brain and other organs". American Journal of Physiology-Endocrinology and Metabolism 253, n. 3 (1 settembre 1987): E317—E321. http://dx.doi.org/10.1152/ajpendo.1987.253.3.e317.
Testo completoAbstract (sommario):
Homogenates of brain, pituitary, liver, lung, ovary, and testes were incubated with [pyro Glu1-3,4-3H]luteinizing hormone-releasing hormone ([3H]LHRH), and the profiles of metabolites generated as a function of time were determined. After 5 min of incubation, 5 was the predominant metabolite in most homogenates. Although the profiles of metabolites varied at different time intervals, metabolites 2, 3, 4, and 5, and in some instances 7 and 9, appeared to form simultaneously and were detectable at 10 min. Neither metabolite 6 nor other larger metabolites formed initially as dominant degradation products. The findings suggest cleavage of LHRH by the simultaneous action of several endopeptidases. After a single vascular transit of [3H]LHRH, metabolites were determined in the venous blood of liver, lung, and brain of rats in vivo. There were no metabolites of [3H]LHRH in venous blood of liver and lung; however, metabolites 2-4 were present in venous blood of the brain. Incubation of rat anterior pituitary cells with [3H]LHRH yielded metabolites 1-4 but not metabolites 5 or 9 as in homogenates. Incubation of [3H]LHRH with porcine follicular granulosa cells resulted in the generation of metabolites 2-7 and 9, similar to the profile in homogenates. Thus, since homogenates contain enzymes of disrupted cells, they do not always reflect mechanisms for in vivo hydrolysis of circulating LHRH. Brain degraded 12.1% of LHRH during a single vascular transit and may account for substantial degradation of the circulating hormone.
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Kar, Soumya, Marinus te Pas, Leo Kruijt, Jacques Vervoort, Alfons Jansman e Dirkjan Schokker. "Sanitary Conditions on the Farm Alters Fecal Metabolite Profile in Growing Pigs". Metabolites 12, n. 6 (11 giugno 2022): 538. http://dx.doi.org/10.3390/metabo12060538.
Testo completoAbstract (sommario):
The aim of this study was to use fecal metabolite profiling to evaluate the effects of contrasting sanitary conditions and the associated subclinical health status of pigs. We analyzed fecal metabolite profiles by nuclear magnetic resonance (1H NMR) from pigs aged 14 and 22 weeks. Pigs kept under low and high sanitary conditions differed in fecal metabolites related to the degradation of dietary starch, metabolism of the gut microbiome, and degradation of components of animal (host) origin. The metabolites that differed significantly (FDR < 0.1) were from metabolic processes involved in either maintaining nutrient digestive capacity, including purine metabolism, energy metabolism, bile acid breakdown and recycling, or immune system metabolism. The results show that the fecal metabolite profiles reflect the sanitary conditions under which the pigs are kept. The fecal metabolite profiles closely resembled the profiles of metabolites found in the colon of pigs. Fecal valerate and kynurenic acid could potentially be used as “non-invasive” biomarkers of immune or inflammatory status that could form the basis for monitoring subclinical health status in pigs.
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Wang, Qinghong, Siyu Li, Xin Wang, Zhuoyu Li, Yali Zhan e Chunmao Chen. "Efficient Degradation of 4-Acetamidoantipyrin Using a Thermally Activated Persulfate System". Sustainability 14, n. 21 (1 novembre 2022): 14300. http://dx.doi.org/10.3390/su142114300.
Testo completoAbstract (sommario):
The extensive use of pharmaceuticals and personal care products (PPCPs) causes high concentrations of pharmaceutical metabolites to exist in aquatic environments. Though the removal of parent PPCPs has raised concerns, the degradation of pharmaceutical metabolites was rarely investigated. In this study, the degradation of 4-acetylaminoantipyrine (4-AAA), a typical dipyrone metabolite frequently detected worldwide in surface water and wastewater, was initially studied using persulfate (PDS)-based advanced oxidation processes (AOPs). Compared with commonly used activation methods of alkali, ultrasonic, ultraviolet, and Fe2+, 4-AAA achieved its best degradation (98.9%) within 30 min in a thermally activated PDS system due to the promotion of both radical production and the reaction rate with the rise in temperature. The optimum degradation of 4-AAA could be achieved with the temperature of 80 °C regardless of initial pH values, indicating a wide suitable pH range. Moreover, over 80% of the degradation of 4-AAA could be achieved with the presence of Cl− (0–16 mM), HCO3− (0–8 mM), and humic acid (0–30 mg/L), further indicating the application potential of the system. Both sulfate radicals (SO4•−) and hydroxyl radicals (•OH) contributed to 4-AAA degradation and the contribution of •OH increased with the pH rising from 3 to 11 due to the transformation from SO4•− when reacting with OH−. Three hydroxylated and ring-opening intermediates were detected during the 4-AAA degradation. The ECOSAR prediction indicated that the acute toxicity of most intermediates decreased than 4-AAA while the chronic toxicity increased, which suggested the transformation of intermediates should be further focused on in SO4•− and •OH based AOPs. This study would provide technical reference for the control of 4-AAA in wastewater treatment processes, raise concerns on the influence of PPCPs metabolites, and throw light on reducing the harm of PPCPs and their metabolites in aquatic environments.
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Hong, Junting, Nadia Boussetta, Gérald Enderlin, Nabil Grimi e Franck Merlier. "Real-Time Monitoring of the Atrazine Degradation by Liquid Chromatography and High-Resolution Mass Spectrometry: Effect of Fenton Process and Ultrasound Treatment". Molecules 27, n. 24 (17 dicembre 2022): 9021. http://dx.doi.org/10.3390/molecules27249021.
Testo completoAbstract (sommario):
High resolution mass spectrometry (HRMS) was coupled with ultra-high-performance liquid chromatography (uHPLC) to monitor atrazine (ATZ) degradation process of Fenton/ultrasound (US) treatment in real time. Samples were automatically taken through a peristaltic pump, and then analysed by HPLC-HRMS. The injection in the mass spectrometer was performed every 4 min for 2 h. ATZ and its degradation metabolites were sampled and identified. Online Fenton experiments in different equivalents of Fenton reagents, online US experiments with/without Fe2+ and offline Fenton experiments were conducted. Higher equivalents of Fenton reagents promoted the degradation rate of ATZ and the generation of the late-products such as Ammeline (AM). Besides, adding Fe2+ accelerated ATZ degradation in US treatment. In offline Fenton, the degradation rate of ATZ was higher than that of online Fenton, suggesting the offline samples were still reacting in the vial. The online analysis precisely controls the effect of reagents over time through automatic sampling and rapid detection, which greatly improves the measurement accuracy. The experimental set up proposed here both prevents the degradation of potentially unstable metabolites and provides a good way to track each metabolite.
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Chen, Xiao-Jun, Zhi-Yuan Meng, Li Ren, Yue-Yi Song, Ya-Jun Ren, Jian-Shu Chen e Ling-Jun Guan. "Determination and Safety Assessment of Residual Spirotetramat and Its Metabolites in Amaranth (Amaranthus tricolor) and Soil by Liquid Chromatography Triple-Quadrupole Tandem Mass Spectrometry". Journal of AOAC INTERNATIONAL 101, n. 3 (1 maggio 2018): 848–57. http://dx.doi.org/10.5740/jaoacint.17-0216.
Testo completoAbstract (sommario):
Abstract With the purpose of guaranteeing the safe use of spirotetramat and preventing its potential health threats to consumers, a QuEChERS extraction method coupled with LC triple-quadrupole tandem MS was applied in this study to determine residual spirotetramat metabolites in different tissues of amaranth (Amaranthus tricolor) and in soil. The results indicate that the spirotetramat degraded into different types of metabolites that were located in different tissues of amaranth and in soil. B-keto, B-glu, and B-enol were the three most representative degradation products in the leaf of amaranth, and B-glu and B-enol were the two major degradation products found in the stem of amaranth; however, only B-enol was detected in the root of amaranth. B-keto and B-mono were the two products detected in the soil in which the amaranth grew. The cytotoxicity results demonstrate that spirotetramat and its metabolite B-enol inhibited cellular growth, and the toxicity of spirotetramat and its metabolite B-enol exceeded than that of the metabolites B-keto, B-mono, and B-glu. This investigation is of great significance to the safe use of spirotetramat in agriculture.
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Wetzstein, Heinz-Georg, Marc Stadler, Hans-Volker Tichy, Axel Dalhoff e Wolfgang Karl. "Degradation of Ciprofloxacin by Basidiomycetes and Identification of Metabolites Generated by the Brown Rot FungusGloeophyllum striatum". Applied and Environmental Microbiology 65, n. 4 (1 aprile 1999): 1556–63. http://dx.doi.org/10.1128/aem.65.4.1556-1563.1999.
Testo completoAbstract (sommario):
ABSTRACT Ciprofloxacin (CIP), a fluoroquinolone antibacterial drug, is widely used in the treatment of serious infections in humans. Its degradation by basidiomycetous fungi was studied by monitoring14CO2 production from [14C]CIP in liquid cultures. Sixteen species inhabiting wood, soil, humus, or animal dung produced up to 35% 14CO2 during 8 weeks of incubation. Despite some low rates of14CO2 formation, all species tested had reduced the antibacterial activity of CIP in supernatants to between 0 and 33% after 13 weeks. Gloeophyllum striatum was used to identify the metabolites formed from CIP. After 8 weeks, mycelia had produced 17 and 10% 14CO2 from C-4 and the piperazinyl moiety, respectively, although more than half of CIP (applied at 10 ppm) had been transformed into metabolites already after 90 h. The structures of 11 metabolites were elucidated by high-performance liquid chromatography combined with electrospray ionization mass spectrometry and 1H nuclear magnetic resonance spectroscopy. They fell into four categories as follows: (i) monohydroxylated congeners, (ii) dihydroxylated congeners, (iii) an isatin-type compound, proving elimination of C-2, and (iv) metabolites indicating both elimination and degradation of the piperazinyl moiety. A metabolic scheme previously described for enrofloxacin degradation could be confirmed and extended. A new type of metabolite, 6-defluoro-6-hydroxy-deethylene-CIP, provided confirmatory evidence for the proposed network of congeners. This may result from sequential hydroxylation of CIP and its congeners by hydroxyl radicals. Our findings reveal for the first time the widespread potential for CIP degradation among basidiomycetes inhabiting various environments, including agricultural soils and animal dung.
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Hosseini, Parastou Khalessi, e Sonia Michail. "COMPARING THE GUT METABOLOMIC PROFILES IN HISPANIC AND NON-HISPANIC PEDIATRIC ULCERATIVE COLITIS PATIENTS". Inflammatory Bowel Diseases 28, Supplement_1 (22 gennaio 2022): S67. http://dx.doi.org/10.1093/ibd/izac015.109.
Testo completoAbstract (sommario):
Abstract BACKGROUND Diagnosis of ulcerative colitis (UC), a subgroup of inflammatory bowel disease (IBD), is frequently overlooked among the Hispanic population. Although previously thought to impact predominantly white populations, epidemiological studies have shown an increased incidence of UC among Hispanics. Other studies have also noted variations in disease phenotype when comparing Hispanic UC patients to non-Hispanic patients. These variations could be linked to differences in the gut microbiome and shifts in the metabolomic profile. This study aims to compare the profiles of Hispanic UC patients to those of non-Hispanic whites. METHODS Participants aged 7-21 with mild to moderate UC were enrolled at Children’s Hospital of Los Angeles. Eighteen Hispanic and forty non-Hispanic patients were included in this analysis. Metabolite profiling yielded 230 known metabolites. Independent sample T-tests were used to identify significant differences (p<0.05) in metabolites between Hispanic and non-Hispanic UC samples. The average for each metabolite was calculated in Hispanic, non-Hispanic, and healthy patients. Averages were then compared and used to define metabolites as enhanced or diminished. RESULTS 66 metabolites were found to be significantly different between Hispanic and non-Hispanic UC patients. When comparing the profiles of Hispanic to that of non-Hispanic patients, 2 metabolites were enhanced and 64 were diminished. The two enhanced metabolites included 1-monostearin and 1-monopalmitin. Figure 1 depicts the top 10 most diminished metabolites in Hispanic patients compared to non-Hispanic patients. These 10 metabolites were amino acids, amino acid degradation products, and one polyol compound. DISCUSSION This study found a significant difference in the metabolomic profiles of Hispanic UC patients compared to non-Hispanics. This difference could suggest a relationship between ethnicity and the gut’s metabolomic profile. Most notably, Hispanic patients were found to have diminished levels of nearly all significantly different metabolites when compared to non-Hispanic patients. This includes protective fatty acids, amino acids, and amino acid degradation byproducts. Increased deficits of protective anti-inflammatory mediators can be linked to increased risk of severe disease among Hispanic UC patients. These findings support the need for therapeutics targeting specific metabolite deficiencies within Hispanic UC patients.
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Urbaniak, Magdalena, Elżbieta Mierzejewska e Maciej Tankiewicz. "The stimulating role of syringic acid, a plant secondary metabolite, in the microbial degradation of structurally-related herbicide, MCPA". PeerJ 7 (10 aprile 2019): e6745. http://dx.doi.org/10.7717/peerj.6745.
Testo completoAbstract (sommario):
The ability of microorganisms to degrade xenobiotics can be exploited to develop cost-effective and eco-friendly bioremediation technologies. Microorganisms can degrade almost all organic pollutants, but this process might be very slow in some cases. A promising way to enhance removal of recalcitrant xenobiotics from the environment lies in the interactions between plant exudates such as plant secondary metabolites (PSMs) and microorganisms. Although there is a considerable body of evidence that PSMs can alter the microbial community composition and stimulate the microbial degradation of xenobiotics, their mechanisms of action remain poorly understood. With this in mind, our aim was to demonstrate that similarity between the chemical structures of PSMs and xenobiotics results in higher micropollutant degradation rates, and the occurrence of corresponding bacterial degradative genes. To verify this, the present study analyses the influence of syringic acid, a plant secondary metabolite, on the bacterial degradation of an herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA). In particular, the presence of appropriate MCPA degradative genes, MCPA removal efficiency and changes in samples phytotoxicity have been analyzed. Significant MCPA depletion was achieved in samples enriched with syringic acid. The results confirmed not only greater MCPA removal from the samples upon spiking with syringic acid, and thus decreased phytotoxicity, but also the presence of a greater number of genes responsible for MCPA biodegradation. 16S rRNA gene sequence analysis revealed ubiquitous enrichment of the β-proteobacteriaRhodoferax, Achromobacter, BurkholderiaandCupriavidus. The obtained results provide further confirmation that plant metabolites released into the rhizosphere can stimulate biodegradation of xenobiotics, including MCPA.
Tesi sul tema "Degradation metabolites"
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Nalli, Sandro. "Biological degradation of plasticizers and their metabolites". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85630.
Testo completoAbstract (sommario):
Plasticizers are widely used as additives for the production of PVC and other types of plastics. They have been observed to leach out of the solid matrix over the course of the lifetime of the finished product. These compounds have now been observed across the globe and in different environments. The main focus of this work is the study of the interactions of industrial plasticizers with soil microorganisms including bacteria, yeast and fungi.This research is concerned with the microbial degradation of plasticizers such as di-2-ethylhexyl phthalate (DEHP) and di-2-ethylhexyl adipate (DEHA). In particular, the study has focused on the stable metabolites produced during biodegradation, including 2-ethylhexanol and 2-ethylhexanoic acid. The first step was to show that these toxic metabolites were found in significant concentrations in the environment. In addition, a series of experiments with a variety of organisms showed how wide spread the ability to produce these metabolites was. Most organisms tested were capable of interacting with the plasticizers and many of these produced the metabolites.
It was apparent that these metabolites could have appreciable stability and an in-depth study with one species of bacteria, R.rhodochrous , showed that the entire initial 2-ethylhexanol component incorporated in the original plasticizers could be accounted for. Some of this was volatile and found in the exit gas of the reactor. This included all of the 2-ethylhexanol and some of the 2-ethylhexanol. These compounds may contribute to the impairment of the quality of indoor air. An overall mass balance showed that while the bacterium could eventually oxidize the 2-ethylhexanol released by hydrolysis to 2-ethylhexanoic acid, it could not degrade this acid. Thus, a summation of the quantities of each of the various metabolites generated equaled the original amount of 2-ethylhexanol in the plasticizer.
A mathematical model was then constructed to include all of the above features of the interaction of R.rhodochrous with the plasticizers DEHA and DEHP. This model included terms for the biological interactions and enzyme kinetics as well as the toxicity and inhibition of bacterial growth by the plasticizers and their metabolites. The increased understanding of the interaction of microbes with plasticizers will lead to a better understanding of the environmental impact of these compounds and their metabolites. The results of this study also demonstrate that when assessing the environmental impact of a compound, it is essential that not only should the impact of the parent compound be considered, but it is essential that the assessment process must also account for impacts associated with degradation products.
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Horn, Owen. "Environmental Contamination by Metabolites of Microbial Degradation of Plasticizers". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92140.
Testo completoAbstract (sommario):
Earlier work with pure cultures has shown that the interaction of microbes with plasticizers leads to the formation ofmetabolites including 2-ethylhexanol and 2ethylhexanoic acid that resist further degradation. The same studies have shown that these compounds exhibit acute toxicity. This work has shown that the ability of soil micro-organisms to produce these metabolites from the degradation ofplasticizers is a general phenomenon. It was also found that the ability of soil organisms to degrade 2ethylhexanoic acid does not seem to be as common. Taken together, it would be expected that partial de gradation products of plasticizers should be observed in the environment. This was confirmed in a variety of environmental samples including sediments, surface waters, tap water, and fresh precipitation. Thus, even in a complex ecosystem, when plasticizers were degraded, the breakdown is not complete and significant amounts of2-ethylhexanoic acid and 2-ethylhexanol were observed. Since it is already weIl established that plasticizers are ubiquitous in the environment, it is expected that their recalcitrant metabolites will also be ubiquitous. This is a concem because, while the plasticizers do not exhibit acute toxicity, their metabolites do.Il a été démontré, lors d'études précédentes faites avec des cultures pures, que l'intéraction de microbes avec des plastifiants mène à la formation de certains métabolites résistant à une dégradation ultérieure, incluant le 2-éthylhexanol ainsi que l'acide 2éthylhexanoïque. Ces mêmes études ont aussi démontré que ces composés ont une toxicité aigue. Le présent ouvrage a démontré que l'habileté à produire ces métabolites à partir de la dégradation de plastifiants est un phénomène généralisé chez les microorganismes provenants des sols. Il a aussi été démontré que l 'habileté de ces microorganismes à dégrader l'acide 2-éthylhexanoïque ne semble pas être aussi répandue. À partir de ces observations, il semble que les produits de la dégradation partielle des plastifiants devraient être observables dans l'environnement. Ceci a été confirmé dans un éventail d'échantillons environnementaux incluant des sédiments, des eaux de surface, des eaux potables municipales et des précipitations. Donc même dans un écosystème complexe, lorsque les plastifiants sont dégradés, la décomposition n'est pas complète et des quantités notables d'acide 2-éthylhexanoïque et de 2-éthylhexanol sont observées. Puisqu'il a déjà été établi que les plastifiants sont omniprésents dans l'environnement, il est prévu que leurs métabolites récalcitrants y seront aussi omniprésents. Ceci présente un intérêt majeur puisque ces métabolites, contrairement aux plastifiants, possèdent une toxicité aigue fr
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Long, Sarah Ann. "Studies of fungal natural products and the degradation of A- and SS-trenbolone". Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1356.
Testo completo
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Edwards, Michael. "Biological activity of anthocyanins and their phenolic degradation products and metabolites in human vascular endothelial cells". Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/50546/.
Testo completoAbstract (sommario):
Human, animal, and in vitro data indicate significant vasoprotective activity of anthocyanins. However, few studies have investigated the activity of anthocyanin degradation products and metabolites which are likely to mediate bioactivity in vivo. The present thesis therefore examined the vascular bioactivity in vitro of anthocyanins, their phenolic degradants, and the potential for interactions between dietary bioactive compounds. Seven treatment compounds (cyanidin-, peonidin-, petunidin- & malvidin-3-glucoside, and protocatechuic, vanillic, and syringic acid) and two treatment combinations (cyanidin-3-glucoside or protocatechuic acid with epicatechin, quercetin, and ascorbic acid) were screened in a human endothelial cell model for effects on endothelial nitric oxide synthase (eNOS) activity (via ELISA & colourimetric assay), and NADPH oxidase (NOX)-mediated superoxide production (by cytochrome c reduction assay, optimised in-house). A bioactive treatment was then chosen to explore possible mechanisms of NOX inhibition, namely gene expression of NOX2, NOX4, p47phox, p67phox, p22phox, & haem oxygenase-1 (HO-1), and activation/expression of p47phox and HO-1 protein; using RT-qPCR and immunoblotting (optimised for cell stimulation conditions and qPCR reference genes). Differential bioactivity of parent anthocyanins and their phenolic degradants was observed at physiologically relevant concentrations, as only anthocyanins upregulated eNOS expression (by 4- to 7-fold; p < 0.01), whereas both anthocyanins and degradants appeared to reduce endothelial superoxide levels (by 1- to 8-fold; p < 0.05). The phenolic degradant vanillic acid significantly reduced (p < 0.05) superoxide by 2-fold at 1μM, and has been reported at low micromolar levels in human serum; therefore vanillic acid was selected to elucidate pathways potentially underlying observed bioactivity. Vanillic acid did not significantly modulate expression of NOX isoforms/subunits, but an apparent induction of the cytoprotective enzyme HO-1 by vanillic acid (2-fold increase) was observed in human umbilical vein and coronary artery endothelial cells, although changes were non-significant (p ≥ 0.3). In conclusion, anthocyanin phenolic degradants could enhance vascular function in vivo by decreasing superoxide production, and thus scavenging of the key mediator nitric oxide (NO). Vanillic acid might inhibit endothelial superoxide production through modulation of HO-1, thereby preserving NO bioavailability and vascular homoeostasis, and this pathway should be the focus of future research.
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Afsarmanesh, Tehrani Rouzbeh. "AEROBIC BACTERIAL DEGRADATION OF HYDROXYLATED PCBs: POTENTIAL IMPLICATIONS FOR NATURAL ATTENUATION OF PCBs". Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/216532.
Testo completoAbstract (sommario):
Civil EngineeringPh.D.
Polychlorinated biphenyls (PCBs) are toxic and persistent chemicals that have been largely dispersed into the environment. The biological and abiotic transformations of PCBs often generate hydroxylated derivatives, which have been detected in a variety of environmental samples, including animal tissues and feces, water, and sediments. Because of their toxicity and widespread dispersion in the environment, hydroxylated PCBs (OH-PCBs) are today increasingly considered as a new class of environmental contaminants. Although PCBs are known to be susceptible to microbial degradation under both aerobic and anaerobic conditions, bacterial degradation of OH-PCBs has received little attention. The overall objective of this study is therefore to evaluate the transformation of mono-hydroxylated PCBs by the well characterized aerobic PCB-degrading bacterium, Burkholderia xenovorans LB400. In order to achieve our overall objective, a series of model mono-hydroxylated PCBs have been selected and they are used to determine the toxicity of hydroxylated congeners toward the bacterium B. xenovorans LB400. The biodegradation kinetics and metabolic pathways of the selected OH-PCBs by B. xenovorans LB400 are then characterized using GC/MS. To understand further the molecular basis of the metabolism of OH-PCBs by B. xenovorans LB400, gene expression analyses are conducted using reverse-transcription real-time (quantitative) polymerase chain reaction (RT-qPCR) and microarray technology. More formally, the specific aims of the proposed research are stated as follows: (1) To evaluate the toxicity of selected mono-hydroxylated derivatives of lesser-chlorinated PCBs toward the bacterium B. xenovorans LB400. (2) To assess the degradation of the selected OH-PCBs by B. xenovorans LB400. (3) To gain further understanding of the molecular bases of the metabolism of the selected OH-PCBs by B. xenovorans LB400. Three hydroxylated derivatives of 4-chlorobiphenyl and 2,5-dichlorobiphenyl, including 2'-hydroxy-, 3'-hydroxy-, and 4'-hydroxy- congeners, were significantly transformed by Burkholderia xenovorans LB400 when the bacterium was growing on biphenyl (biphenyl pathway-inducing conditions). On the contrary, only 2'-OH-4-chlorobiphenyl and 2'-OH-2,5-dichlorobiphenyl were transformed by the bacterium growing on succinate (conditions non-inductive of the biphenyl pathway). Gene expression analyses showed that only exposure to 2'-OH-4-chlorobiphenyl and 2'-OH-2,5-dichlorobiphneyl resulted in induction of key genes of the biphenyl pathway, when cells grown on succinate. These observations suggest that 2'OH-PCBs were capable of inducing the genes of biphenyl pathway. These results provide the first evidence that bacteria are able to cometabolize PCB derivatives hydroxylated on the non-chlorinated ring. Genome-wide transcriptional analyses using microarrays showed that 134 genes were differentially expressed in cells exposed to biphenyl, 2,5-dichlorobiphenyl, and 2'-OH-2,5-dichlorobiphneyl as compared to non-exposed cells. A significant proportion of differentially expressed genes were simultaneously expressed or down regulated by exposure to the three target compounds i.e., biphenyl, 2,5-DCB, and 2'-OH-2,5-DCB, which suggests that these structurally similar compounds induce similar transcriptional response of B.xenovorans LB400. Results of this study may have important implications for the natural attenuation of PCBs and fate of OH-PCBs in the environment. The recalcitrance to biodegradation and the high toxicity of some OH-PCBs may provide a partial explanation for the persistence of PCBs in the environment.
Temple University--Theses
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Mardal, Marie [Verfasser]. "Studies on the biotransformation/degradation pathways of drugs of abuse and their main human metabolites in wastewater / Marie Mardal". Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2017. http://d-nb.info/1227925484/34.
Testo completo
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CANAVESI, ROSSANA. "Chemical and metabolic stability studies of propargylamine-containing drugs". Doctoral thesis, Università del Piemonte Orientale, 2016. http://hdl.handle.net/11579/115197.
Testo completo
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McClean, Stephen. "An investigation of modern analytical techniques for the identification and determination of selected drugs and pollutants, their degradation products and metabolites". Thesis, University of Ulster, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322413.
Testo completo
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Lentola, Andrea. "Systemic insecticides, their degradation products and metabolites in the environment. Quantification methodologies in environmental samples relevant for toxicological and ecotoxicological studies". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3427171.
Testo completoAbstract (sommario):
Systemic insecticides are widely used for pests control and their success is due to their ability of protect the whole plant from roots to the upper leaf. In particular, seeds coating technique is very popular and it is applied to many crops (e.g. corn). However, the use of high amount of Active Ingridient (AI) for seeds coating is causing concern about negative effects to non-target animals. Pollinators insects are exposed to contaminated pollen and nectar, but also herbivore insects are exposed through contaminated leaf. In addition, these insecticides can leach from fields and contaminate wild plants or waterbodies. Therefore, also aquatic species are exposed to insecticides pollution and vertebrates like birds and small mammals could be exposed through coated seeds, seedling and insects.
The aim of this study was to develop an UHPLC-HRMS method for the identification of insecticides and their degradation production in corn guttation drops. Particular attention was posed to metabolites, because few information are available in the literature about their presence in relevant matrix for eco-toxicological studies. In addition, some metabolites may have greater toxicity if compared with their parent compounds. In particular, neonicotinoids imine metabolites are characterised by an inversion of selectivity between insects and mammals. Therefore, they can be more toxic for mammals if compared to the neonicotinoids AI.
Several metabolites were identify in corn guttation and an extraction procedure based on QuEChERS strategy coupled with a target UHPLC-MS2 method was developed and validated for the quantification of these compounds in corn leaf. High concentration of neonicotinoids thiamethoxam and thiacloprid were observed in corn seedling. In addition, high concentration of the thiamethoxam metabolite clothianidn was observed. Concerning the carbamate methiocarb, the AI was observed only at low concentration, but its metabolites were present at ug/g level. Particularly interesting was the presence of methiocarb sulfoxide, because this metabolite is more toxic of the parent compounds for some species.
In conclusion, guttation analysis with UHPLC-HRMS is a powerful technique in order to assess the presence of insecticides metabolites in plants treated with systemic AI. However, UHPLC-MS2 still provide better performance for quantitative analysis, in particular for complex matrices as corn leaf. Therefore, HRMS and MS2 are complementary technique useful to provide levels of contamination and exposure.Systemic insecticides are widely used for pests control and their success is due to their ability of protect the whole plant from roots to the upper leaf. In particular, seeds coating technique is very popular and it is applied to many crops (e.g. corn). However, the use of high amount of Active Ingridient (AI) for seeds coating is causing concern about negative effects to non-target animals. Pollinators insects are exposed to contaminated pollen and nectar, but also herbivore insects are exposed through contaminated leaf. In addition, these insecticides can leach from fields and contaminate wild plants or waterbodies. Therefore, also aquatic species are exposed to insecticides pollution and vertebrates like birds and small mammals could be exposed through coated seeds, seedling and insects. The aim of this study was to develop an UHPLC-HRMS method for the identification of insecticides and their degradation production in corn guttation drops. Particular attention was posed to metabolites, because few information are available in the literature about their presence in relevant matrix for eco-toxicological studies. In addition, some metabolites may have greater toxicity if compared with their parent compounds. In particular, neonicotinoids imine metabolites are characterised by an inversion of selectivity between insects and mammals. Therefore, they can be more toxic for mammals if compared to the neonicotinoids AI. Several metabolites were identify in corn guttation and an extraction procedure based on QuEChERS strategy coupled with a target UHPLC-MS2 method was developed and validated for the quantification of these compounds in corn leaf. High concentration of neonicotinoids thiamethoxam and thiacloprid were observed in corn seedling. In addition, high concentration of the thiamethoxam metabolite clothianidn was observed. Concerning the carbamate methiocarb, the AI was observed only at low concentration, but its metabolites were present at ug/g level. Particularly interesting was the presence of methiocarb sulfoxide, because this metabolite is more toxic of the parent compounds for some species. In conclusion, guttation analysis with UHPLC-HRMS is a powerful technique in order to assess the presence of insecticides metabolites in plants treated with systemic AI. However, UHPLC-MS2 still provide better performance for quantitative analysis, in particular for complex matrices as corn leaf. Therefore, HRMS and MS2 are complementary technique useful to provide levels of contamination and exposure.
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Minetto, Luciane. "Antibióticos macrolídeos: determinação e identificação de metabólitos e subprodutos de degradação em efluente hospitalar". Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/4262.
Testo completoAbstract (sommario):
Conselho Nacional de Desenvolvimento Científico e TecnológicoMacrolide antibiotics are an important group of prescription drugs; as a consequence of the large and continuous use, they are commonly found in the environment. In the present study, it was developed and optimized a chromatographic method to assess the occurrence of macrolide antibiotics Azithromycin, Clarithromycin, Erythromycin and Roxithromycin in the effluent of the University Hospital of Santa Maria, in two sampling points, by applying high performance liquid chromatography coupled to mass detection with quadrupole ion trap (HPLC-MS/MS_QTrap) and clean-up/pre-concentration by solid phase extraction with the aid of Surface Methodology Response. The concentrations measured during a week in the hospital effluent were 1.32±0.13 and 0.22±0.06 μg L-1 for Azithromycin and Clarithromycin; in the receptor water sream was 1.12±0.20, 0.20±0.05 and 0.01±0.004 μg L-1 for Azithromycin, Clarithromycin and Erythromycin. Roxithromycin was not detected in all effluent samples. After this, it was done the evaluation of the risk quotient of the macrolide antibiotics. The value of the risk quotient for the hospital effluent for Azithromycin and Clarithromycin was 11 (high risk), and for the receptor water stream the risk quotient was 9.3 and 10.0 for Azithromycin and Clarithromycin; for Erythromycin, a quocient risk value of 0.5 (medium risk). For degradation of the antibiotics in aqueous solution, it was used UV-photolysis, by which the influence of pH (3-11) was evaluated. Azithromycin showed low degradation by acid pH; for other pH, as well, for all the other antibiotics, the degradation was above 70% after 60 min of treatment. It was conducted a kinetic study of the degradation process of macrolide antibiotics in different pHs, by which Azithromycin revealed a recalcitrant profile, and Roxithromycin, as the more easily degradable one. For identification of the products formed during the photolysis experiments it was used independent information acquisition and as precursor ions of fragments m/z 116 and 158, characteristic of the macrolide compounds, at three collision energies (30, 45, and 60 V). It was proposed fragmentation routes of the degradation products: 8 products for Azithromycin, 7 for Clarithromycin, 6 of Erythromycin and 8 Roxithromycin. Through the same experiments with independent information acquisition, it was investigated the presence of eventual metabolites in hospital effluent, and three metabolites were found. By applying photolysis to the hospital effluent fortified, at pH 7, it was observed that the degradation occurs above 80% for all compounds after 60 min of irradiation. It was observed the formation of degradation products previously determined by experiments in aqueous solution. It was also found three degradation products for Azithromycin, 2 for Clarithromycin, 1 for Erythromycin and 3 for Roxithromycin.
Os antibióticos macrolídeos são uma importante classe de fármacos preescritos no tratamento das mais variadas infecções, e como consequência se seu grande e continuo uso são comumente encontradas no ambiente. No presente estudo foi desenvolvido e otimizado método de cromatografia líquida de alta eficiência acoplada à detector de massas quadrupolo íon trap (HPLC-MS/MS_QTrap) e de clean-up/pré-concentração por extração em fase sólida com auxílio de Metodologia de Superfície de Resposta para avaliar a ocorrência dos antibióticos macrolídeos Azitromicina, Claritromicina, Eritromicina e Roxitromicina no efluente hospitalar do Hospital Universitário de Santa Maria em dois ponto de amostragem. As concentrações médias durante o ciclo de uma semana de amostragem no efluente do pronto atendimento foram de 1,32±0,13 e 0,22±0,06 g L-1 para Azitromicina e Claritromicina; no corpo recpetor foram de 1,12±0,20; 0,20±0,05 e 0,01±0,004 g L-1 para Azitromicina, Claritromicina e Eritromicina, respectivamente. Roxitromicina não foi detectada. Após foi feita a avaliação do quociente de risco dos antibióticos macrolídeos. O quociente de risco no efluente do pronto atendimento para Azitromicina e Claritromicina foi de 11, risco alto, o qual também foi evidenciado no corpo receptor com quociente de risco de 9,3 e 10 para Azitromicina e Claritromicna, e risco médio para Eritromicina de 0,5. Para degradação dos antibióticos foi utilizado fotólise artificial em solução aquosa, sendo avaliado a influência do pH de 3-11 na degradação destes compostos. Azitromicina apresentou baixa degradação em pH ácido, para os outros pH e demais compostos a degradação foi acima de 70% após 60 min de tratamento. Foi feito um estudo cinético do processo de degradação dos antibióticos macrolídeos em diferentes pH, observando-se que a Azitromicina apresentou um perfil recalcitrante para o processo, e Roxitromicina foi degradada com maior facilidade. Para a identificação dos produtos formados durante os experimentos de fotodegradação foram montados experimentos de informação independente de aquisição utilizando como íons precursores os íons de m/z 116 e 158 característicos dos compostos macrolídeos em três energias de colisão (30, 45 e 60 V). Foram identificadas e propostas rotas de fragmentação para 8 produtos de degradação de Azitromicina, 7 para Claritromicina, 6 para Eritromicina e 8 produtos de degradação de Roxiromicina. Através dos mesmos experimentos de informação independente de aquisição, foi investigada a presença de possíveis metabólitos no efluente hospitalar sendo encontrados 3 metabólitos. Com a aplicação de fotólise ao efluente hospitalar fortificado, em pH 7, observou-se que ocorre degradação acima de 80% para todos os compostos após 60 min de tratamneto. Foi observada a formação de produtos de degradação, que tinham sido previamente determinados em solução aquosa. Foram encontrados 3 produtos de degradação de Azitromicina, 2 para Claritromicina, 1 para Eritromicina e 3 produtos para Roxitromicina.
Libri sul tema "Degradation metabolites"
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McClean, Stephen. An investigation of modern analytical techniques for the identification and determination of selected drugs and pollutants, their degradation products and metabolites. [S.l: The Author], 1999.
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Ratledge, Colin. Biochemistry of microbial degradation. Springer, 2011.
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Ratledge, Colin. Biochemistry of Microbial Degradation. Springer London, Limited, 2012.
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Ratledge, Colin. Biochemistry of microbial degradation. Springer, 2012.
Cerca il testo completoCapitoli di libri sul tema "Degradation metabolites"
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Lerch, Robert N., William W. Donald, Yong-Xi Li e Eugene E. Alberts. "Hydroxylated Atrazine Degradation Products in a Small Missouri Stream". In Herbicide Metabolites in Surface Water and Groundwater, 254–70. Washington, DC: American Chemical Society, 1996. http://dx.doi.org/10.1021/bk-1996-0630.ch019.
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Roberts, Clive R., John S. Mort e Peter J. Roughley. "Degradation of the Proteoglycans of Human Articular Cartilage by Reactive Oxygen Metabolites". In Oxygen Radicals in Biology and Medicine, 353–56. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-5568-7_53.
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Felix, A. M., T. Lambros, E. P. Heimer, H. Cohen, Y. C. Pan, R. Campbell e J. Bongers. "Degradation of growth hormone releasing factor in aqueous solution: Isolation and characterization of major metabolites". In Peptides 1990, 732–33. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3034-9_303.
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Christoph, N., M. Geßner, T. J. Simat e K. Hoenicke. "Off-Flavor Compounds in Wine and Other Food Products Formed By Enzymatical, Physical, and Chemical Degradation of Tryptophan and its Metabolites". In Advances in Experimental Medicine and Biology, 659–69. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4709-9_85.
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Verdini, Antonio S. "Biological activities of thymopentin, tuftsin and neurotensin(8–13) are profoundly influenced by metabolites resulting from enzymatic degradation of their retro-inverso analogues". In Peptides, 15–18. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-010-9066-7_4.
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Warriner, Keith, e Svetlana Zivanovic. "Microbial Metabolites in Fruits and Vegetables". In Produce Degradation, 505–28. CRC Press, 2005. http://dx.doi.org/10.1201/9781420039610.ch17.
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Pratap Singh, Aditya, Ponaganti Shiva Kishore, Santanu Kar e Sujaya Dewanjee. "Secondary Metabolites of Brassica juncea (L.) Czern and Coss: Occurence, Variations and Importance". In Brassica - Recent Advances [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107911.
Testo completoAbstract (sommario):
There are numerous secondary plant metabolites found in the crop B. juncea, especially glucosinolates. Isothiocyanates, the by-products of glycosinolate breakdown, are beneficial to human health. A number of studies have also called attention to phenolic compounds and carotenoids, both well known for their anti-oxidant properties. A notable feature is that the profiles and concentrations of secondary plant metabolites vary greatly between varieties and that genetic factors are thought to be the most significant factors. In addition, environmental and agronomic factors have also been noted to change the concentrations of secondary plant metabolites. Secondary plant metabolites are primarily produced for defense purposes. Consequently, the intrinsic quality of Indian mustard, including color, aroma, taste, and medicinal properties, is profoundly influenced by its secondary metabolite profile. The health benefits of glycosinolates and the cancer prevention properties of their breakdown products make them of specific interest. Plant cells that have been injured undergo enzymatic decomposition of glucosinolate by endogenous enzymes such as myrosinase, which releases degradation products such as nitriles, epithionitriles, or isothiocyanates. The main phenolic compounds found in B. juncea are flavonoids and hydroxycinnamic acid derivatives. A diverse secondary metabolite pool is also essential for plant-environment interactions.
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McKee, Trudy, e James R. McKee. "Nitrogen Metabolism II: Degradation". In Biochemistry. Oxford University Press, 2020. http://dx.doi.org/10.1093/hesc/9780190847685.003.0015.
Testo completoAbstract (sommario):
This chapter deals with the metabolism of nitrogen-containing molecules, such as proteins and nucleic acids, that differs significantly from that of carbohydrates and lipids. Whereas the latter molecules can be stored and mobilized when needed for biosynthetic reactions or for energy generation, there is no nitrogen-storing molecule. The chapter elaborates how organisms must constantly replenish their supply of usable nitrogen to replace organic nitrogen that is lost in catabolism. It mentions the turnover of protein and nucleic acids, which is one of the most obvious aspects of cellular renovation and is a process that results in the continuous flow of nitrogen atoms through living organisms. Living organisms recycle organic nitrogen into a variety of metabolites before the element is reconverted to its inorganic form.
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Lammers-Jannink, Kim C. M., Stefanía Magnúsdóttir, Wilbert F. Pellikaan, John Pluske e Walter J. J. Gerrits. "Microbial protein metabolism in the monogastric gastrointestinal tract: a review". In Understanding gut microbiomes as targets for improving pig gut health, 435–66. Burleigh Dodds Science Publishing, 2022. http://dx.doi.org/10.19103/as.2021.0089.23.
Testo completoAbstract (sommario):
Dietary and endogenous protein that become available for the microbiota in the hindgut can be metabolized via different routes. They can become building blocks for the microbial cells or enter different catabolic pathways. Protein degradation via fermentation pathways is seen as a non-preferred route as it results in the formation and release of metabolites that can interfere with biological systems in the host and can have deleterious outcomes. Reducing protein fermentation and guiding the metabolism towards less toxic end-products might be possible targets for improving host health. To do so, more knowledge on factors manipulating the process of microbial protein metabolism, including on substrate availability, microbial composition and segmental differences in the hindgut, is required.
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Chowdhury, Parul. "Glucosinolates and its Role in Mitigating Abiotic and Biotic Stress in Brassicaceae". In Plant Stress Physiology - Perspectives in Agriculture [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102367.
Testo completoAbstract (sommario):
Abiotic stresses such as increase in daily mean temperature, changed patterns of precipitation, increase in episodes of drought and floods in future are faced by the plants and pose threats to crop production and food security. Induction of secondary metabolites by several abiotic stress conditions can be helpful in the crop protection against biotic stress and can be a major link between biotic and biotic stress. Plants also face threats by injury caused by herbivores and insects that chew on plants. Plant develops, coordinates and combines defence mechanism to cope with the challenges caused by the injuries. The plant family Brassicaceae (or Cruciferae) includes some of the world’s most economically important crops; especially members of the genera Brassica L. Brassicaceae vegetables are a good source of secondary metabolite that is Glucosinolates. Which are responsible for characteristic flavour and odour, when degraded. Glucosinolates and their degradation products play important roles in stress tolerance, plants respond to abiotic and abiotic stress by systematically accumulating higher levels primary and secondary metabolites for increasing their resistance. Glucosinolates play important role and have a relation with biotic and abiotic stress in Brassica plant family, as they can act as a signalling molecules and affect the physiology of plant.
Atti di convegni sul tema "Degradation metabolites"
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Statsyuk, N. V., L. A. Shcherbakova, O. D. Mikityuk, T. A. Nazarova e V. G. Dzhavakhiya. "Mycotoxin degradation by microbial metabolites". In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.234.
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Extracellular metabolites of Gliocladium roseum GRZ7 are able to destroy aflatoxin B1 and zearalenone (by 61.9 and 68%, respectively). The determined optimum pH and temperature confirm the enzymatic nature of these metabolites.
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Zang, Shuyan, e Panpan Li. "Influence of Surfactant-Tween80 on Degradation of Benzo(a)Pyrene and Its Accumulated Metabolites by Bacillus-07". In 2010 4th International Conference on Bioinformatics and Biomedical Engineering (iCBBE). IEEE, 2010. http://dx.doi.org/10.1109/icbbe.2010.5517098.
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Dekić, Milan S., e Amina M. Gusinac. "THE AUTOLYSIS PRODUCTS OF GLUCOSINOLATES IN „LEPIDIUM CAMPESTRE“ (L.) W. T. AITON (BRASSICACEAE)". In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.367d.
Testo completoAbstract (sommario):
Plant samples of Lepidium campestre (L.) W. T. Aiton (pepperwort) were analyzed in detail by GC and GC-MS. The analysis of the autolysates obtained from inflorescences, stems, leaves, and underground parts and the essential oil obtained by hydrodistillation allowed the identification of a series of glucosinolate degradation products, mainly isothiocyanates and nitriles. Besides previously identified ones in this species, the analyses resulted in the identification of degradation metabolites identified in pepperwort for the first time, and suggested the presence of heptyl glucosinolate, 3- phenylpropyl glucosinolate, glucoiberverin, glucoiberin, sinalbin, glucoerucin, glucoberteroin, gluconasturtiin, glucolepigramin, glucolesquerellin, glucobrassicanapin, and glucotropaeolin in this species as the most likely glucosinolate precursors. The results showed the localized accumulation of glucoberteroin, glucoerucin, and glucolesquerellin in the roots, the plant organ most exposed to pathogens, whereas sinalbin and glucobrassicanapin were accumulated in the reproductive organs and the organs most exposed to herbivores, i.e. in the aerial parts of the plant.
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Brito, Jordana T., Lucas H. Martorano, Ana Carolina F. de Albuquerque, Carlos Magno Rocha Ribeiro, Rodolfo Goetze Fiorot, José Walkimar de Mesquita Carneiro, Alessandra L. Valverde e Fernando Martins dos Santos Junior. "ESPECTROSCOPIA COMPUTACIONAL APLICADA AO REASSINALAMENTO ESTRUTURAL DE MOLÉCULAS QUIRAIS: HELIANNUOL L". In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202025.
Testo completoAbstract (sommario):
In the past, structure determination of natural products was an arduous process depending almost entirely on chemical synthesis, mainly by derivatization and degradation processes, taking years of effort. Recently, structural elucidation of natural products has undergone a revolution. Nowadays, with the combined use of different advanced spectroscopic methods, it became possible to completely assign the structure of natural products using small amounts of sample. However, despite the extraordinary ongoing advances in spectroscopy, the mischaracterization of natural products has been and remains a recurrent problem, especially in the presence of several chiral centers. The misinterpretation of NMR data has resulted in frequent reports addressing the issue of structural reassignment. In this context, a great effort has been devoted to the development of quantum chemical calculations to predict NMR parameters, and thus achieve a more accurate spectral interpretation. In this work, we applied a protocol for theoretical calculations of 1H NMR chemical shifts in order to establish the correct and unequivocal structure of Helianuol L, a member of the Heliannuol’s class, isolated from Helianthus annus. These secondary metabolites present a broad spectrum of biological activities, including the allelochemical activity, making them promising candidates as natural agrochemicals. It is worth mentioning, however, that the process of elucidating the structure of Heliannuol L was based on structural correlations with molecules already known in the literature, where few stereochemical analyses were performed. In this way, based on the fact that other compounds of the Heliannuol’s class had their structure previously reassigned, the verification of the proposed structure of Heliannuol L becomes of great importance.
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Coma, Silvia, Jill Cavanaugh, James Nolan, Jeremy Tchaicha, Karen McGovern, Everett Stone, Candice Lamb et al. "Abstract 3757: Targeting the IDO/TDO pathway through degradation of the immunosuppressive metabolite kynurenine". In Proceedings: AACR Annual Meeting 2018; April 14-18, 2018; Chicago, IL. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1538-7445.am2018-3757.
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Ketmalee, Thanapong, Thanachai Singhapetcharat, Monrawee Pancharoen, Pacharaporn Navasumrit, Kittiphop Chayraksa e Naruttee Kovitkanit. "Like Cures Like Microbial Enhanced Oil Recovery in Biodegraded Crude". In International Petroleum Technology Conference. IPTC, 2023. http://dx.doi.org/10.2523/iptc-22733-ms.
Testo completoAbstract (sommario):
Abstract Field A is an onshore oil field in Thailand. This area contains biodegraded medium-heavy crude reservoir; 19°API oil gravity and 144 cp viscosity. Therefore, the field suffers from a low recovery factor due to high crude viscosity. On one hand, bacteria have exerted an adverse effect on production, on the other hand, it means that the condition of the reservoir is suitable for implementing Microbial Enhanced Oil Recovery (MEOR). The MEOR is a technology that utilizes microorganisms (mainly bacteria), to enhance oil production, especially for medium-heavy oil. By feeding nutrients to bacteria, several metabolites were produced that would be useful for oil recovery. This technique is well known for its low investment cost, hence, high return. The technical screening confirmed that the reservoir and fluid properties are suitable for MEOR. Consequently, sixteen core samples and three water samples were collected for indigenous bacteria analysis. Although the laboratory indicated there are countless bacterial strains in the reservoir, the nitrate-reducing biosurfactant-producing bacteria group was identified. This bacteria group belongs to the Bacillus genus which produced biosurfactant and reduced crude viscosity by long-chain hydrocarbon degradation. Therefore, the treatment design aimed to promote the growth of favorable bacteria and inhibit undesirable ones. Consequently, a combination of KNO3 and KH2PO4 solutions and a specialized injection scheme was tailored for this campaign. The pilot consisted of two candidates those were well W1 (76% water cut), and well W2 (100% water cut). The campaign was categorized into three phases, namely, 1.) baseline phase, 2.) injection and soaking phase, and 3.) production phase. Firstly, the baseline production trends of candidates were established. Secondly, KNO3 and KH2PO4 solutions were injected for one month then the wells were shut-in for another month. Lastly, the pilot wells were allowed to produce for six months to evaluate the results. The dead oil viscosity of well W1 was reduced from 144 cp to 72 cp which led to a 6.44 MSTB EUR gain or 1.3% RF improvement. On the other hand, the productivity of well W2, the well with 100% water cut, was not improved. This was expected due to insufficient in-situ oil saturation for a bacteria carbon source. Considering the operational aspect, there was no corrosion issue or artificial lift gas-lock problem during the pilot.
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Zhang, Michelle, Everett Stone, Todd A. Triplett, Kendra Triplett, Candice Lamb, Christos S. Karamitros, John Blazek, George Georgiou e Mark G. Manfredi. "Abstract 5570: A novel approach to targeting the IDO/TDO pathway through degradation of the immunosuppressive metabolite kynurenine". In Proceedings: AACR Annual Meeting 2017; April 1-5, 2017; Washington, DC. American Association for Cancer Research, 2017. http://dx.doi.org/10.1158/1538-7445.am2017-5570.
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Maniglio, Marco, Giacomo Rivolta, Ahmed Elgendy, Paola Panfili e Alberto Cominelli. "Evaluating the Impact of Biochemical Reactions on H2 Storage in Depleted Gas Fields". In SPE Annual Technical Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/215142-ms.
Testo completoAbstract (sommario):
Abstract Underground Hydrogen Storage (UHS) is an emerging technology to store energy, produced by renewable sources, into subsurface porous formations. UHS efficiency in depleted gas reservoirs can be affected by H2 biochemical degradation due to interactions with rock, brine and gas. In the reservoir, subsurface microorganisms can metabolize H2 with possible hydrogen losses, H2S production, clogging and formation damage. In this work we investigate the impact of hydrogen losses due to microbial activities on UHS operations in depleted gas reservoirs lying in sandstone formations. We developed a workflow to exploit the chemical reactive transport functionalities of a commercial reservoir simulator, to model biochemical processes occurring in UHS. Kinetic chemical reaction formulation was used to replicate a Monod's type microorganism growth, using PHREEQC to tune reaction parameters by matching a 0-D process in an ideal reactor. Then, we applied the methodology to evaluate the impact of biotic reactions on UHS operations in depleted gas fields. Eventually, various sensitivities were carried out considering injection/production cycles lengths, cushion gas volumes and microbial model parameters. Benchmark against PHREEQC demonstrated that, by properly tuning the kinetic reaction model coefficients, we are capable of adequately reproduce Monod-like growth and competition of different microbial community species. Field-scale results showed that hydrogen losses due to biochemistry are limited, even though this may depend on the availability of reactants in the specific environment: in this work we focus on gas reservoirs where the molar fraction of the key nutrient, CO2, is small (< 2%) and the formation is a typical sandstone. Operational parameters, e.g. storage cycle length, have an impact on the biochemical dynamics and, then, on the hydrogen degradation and generation of undesired by-products. Similar considerations hold for the model microbial growth kinetic parameters: in this study they were established using available literature data for calibration, but we envisage to tune them using experimental results on specific reservoirs. The current model set-up does not account for rock-fluid geochemical interactions, which may result in mineral precipitation/dissolution affecting the concentration of substrates available for biotic reactions. Nonetheless, it can provide an estimate of hydrogen consumption during storage in depleted gas reservoirs due to microbial activities. This study is among the first attempts to evaluate the impact of hydrogen losses by the presence of in situ microbial populations during hydrogen storage in a realistic depleted gas field. The assessment was performed by implementing a novel workflow to encapsulate biochemical reactions and bacterial dynamic-growth in commercial reservoir simulators, which may be applied to estimate the efficiency and associated risks of future UHS projects.
Rapporti di organizzazioni sul tema "Degradation metabolites"
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KHASAEVA, Igor PARSHIKOV e ZARAISKY. DEGRADATION OF 4-METHYLPYRIDINE BY ARTHROBACTER SP. Intellectual Archive, dicembre 2020. http://dx.doi.org/10.32370/iaj.2462.
Testo completoAbstract (sommario):
In the process of degradation of 4-methylpyridine by bacterium Àrthrobacter sp. KM-4MP were isolated two metabolites and identified as 4-methylpyridin-2-ol and 8-hydroxy-4-methylidene-1Hcyclopenta[ 1,2-b:3,4-c’]dipyridine-2,3,5,7(4H,6H)-tetrone.
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Khasaeva, Fatima, Igor Parshikov e Evgeny Zaraisky. Degradation of 2,6-dimethylpyridine by Arthrobacter crystallopoietes. Intellectual Archive, dicembre 2020. http://dx.doi.org/10.32370/iaj.2463.
Testo completoAbstract (sommario):
Degradation of pyridines in waste water is an important issue for chemical and pharmaceutical industries. The biodegradation of 2,6-dimethylpyridine was investigated by the bacterium Arthrobacter crystallopoietes KM-4, which resulted in the formation of three metabolites: 2,6-dimethylpyridin-3-ol, 2,6-dimethylpyridin- 3,4-diol, and 2,4-dioxopentanoic acid.
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Amir, Rachel, David J. Oliver, Gad Galili e Jacline V. Shanks. The Role of Cysteine Partitioning into Glutathione and Methionine Synthesis During Normal and Stress Conditions. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7699850.bard.
Testo completoAbstract (sommario):
The objective of this research is to study the nature of the competition for cysteine (Cys), the first organic sulfur-containing compound, between its two main metabolites, glutathione (GSH) and methionine (Met). GSH plays a central role in protecting plants during various stresses, while Met, an essential amino acid, regulates essential processes and metabolites in plant cells through its metabolite S-adenosyl-Met. Our results, which are based on flux analysis and measurements of Met- metabolites, show that the flux towards Met synthesis is high during non-stress conditions, however the flux is significantly reduced under stress conditions, when there is high synthesis of GSH. Under oxidative stress the expression level of the regulatory enzyme of Met synthesis, cystathionine g-synthase (CGS) was reduced. By using three different systems, we have found that that GSH down regulates the expression level of CGS, thus reducing Met synthesis. We have found that this regulation occurs at the post-transcriptional level, and further studies have shown that it occurs at post-translationaly. To reveal how oxidative stress affects the flux towards Met and GSH, flux analysis was performed. We have found that the level of Met is significantly reduced, while the level of glutathione significantly increases during stress. Under stress conditions most of the glutathione is converted from GSH to GSSG (the oxidised form of glutathione). These results suggest that under normal growth conditions, Cys is channelled towards both pathways to support GSH accumulation and the synthesis of growth-essential Met metabolites. However, during oxidative stress, when a high level of GSH is required to protect the plants, the levels of GSH increase while those of CGS are reduced. This reduction leaves more Cys available for GSH synthesis under stress conditions. In addition we have also studied the effects of high GSH level on the transcriptome profile. The analysis revealed that GSH affects the expression level of many major genes coding to enzymes or proteins associated with photosynthesis, starch degradation, hormone metabolism (especially genes associated with jasmonate), biotic stress (especially genes associated with PR-proteins), cytochrome P450 genes, regulation of transcription and signaling (especially genes associated with receptor kinases and calcium). These results suggest that indeed GSH levels affect different pathways and metabolites in plants.
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Borch, Thomas, Yitzhak Hadar e Tamara Polubesova. Environmental fate of antiepileptic drugs and their metabolites: Biodegradation, complexation, and photodegradation. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7597927.bard.
Testo completoAbstract (sommario):
Many pharmaceutical compounds are active at very low doses, and a portion of them regularly enters municipal sewage systems and wastewater-treatment plants following use, where they often do not fully degrade. Two such compounds, CBZ and LTG, have been detected in wastewater effluents, surface waters, drinking water, and irrigation water, where they pose a risk to the environment and the food supply. These compounds are expected to interact with organic matter in the environment, but little is known about the effect of such interactions on their environmental fate and transport. The original objectives of our research, as defined in the approved proposal, were to: Determine the rates, mechanisms and products of photodegradation of LTG, CBZ and selected metabolites in waters exposed to near UV light, and the influence of DOM type and binding processes on photodegradation. Determine the potential and pathways for biodegradation of LTG, CBZ and selected metabolites using a white rot fungus (Pleurotusostreatus) and ADP, and reveal the effect of DOM complexation on these processes. Reveal the major mechanisms of binding of LTG, CBZ and selected metabolites to DOM and soil in the presence of DOM, and evaluate the effect of this binding on their photodegradation and/or biodegradation. We determined that LTG undergoes relatively slow photodegradation when exposed to UV light, and that pH affects each of LTG’s ability to absorb UV light, the efficiency of the resulting reaction, and the identities of LTG’sphotoproducts (t½ = 230 to 500 h during summer at latitude 40 °N). We observed that LTG’sphotodegradation is enhanced in the presence of DOM, and hypothesized that LTG undergoes direct reactions with DOM components through nucleophilic substitution reactions. In combination, these data suggest that LTG’s fate and transport in surface waters are controlled by environmental conditions that vary with time and location, potentially affecting the environment and irrigation waters. We determined that P. ostreatusgrows faster in a rich liquid medium (glucose peptone) than on a natural lignocellulosic substrate (cotton stalks) under SSF conditions, but that the overall CBZ removal rate was similar in both media. Different and more varied transformation products formed in the solid state culture, and we hypothesized that CBZ degradation would proceed further when P. ostreatusand the ᵉⁿᶻʸᵐᵃᵗⁱᶜ ᵖʳᵒᶠⁱˡᵉ ʷᵉʳᵉ ᵗᵘⁿᵉᵈ ᵗᵒ ˡⁱᵍⁿⁱⁿ ᵈᵉᵍʳᵃᵈᵃᵗⁱᵒⁿ. ᵂᵉ ᵒᵇˢᵉʳᵛᵉᵈ ¹⁴C⁻Cᴼ2 ʳᵉˡᵉᵃˢᵉ ʷʰᵉⁿ ¹⁴C⁻ᶜᵃʳᵇᵒⁿʸˡ⁻ labeled CBZ was used as the substrate in the solid state culture (17.4% of the initial radioactivity after 63 days of incubation), but could not conclude that mineralization had occurred. In comparison, we determined that LTG does not degrade in agricultural soils irrigated with treated wastewater, but that P. ostreatusremoves up to 70% of LTG in a glucose peptone medium. We detected various metabolites, including N-oxides and glycosides, but are still working to determine the degradation pathway. In combination, these data suggest that P. ostreatuscould be an innovative and effective tool for CBZ and LTG remediation in the environment and in wastewater used for irrigation. In batch experiments, we determined that the sorption of LTG, CBZ and selected metabolites to agricultural soils was governed mainly by SOM levels. In lysimeter experiments, we also observed LTG and CBZ accumulation in top soil layers enriched with organic matter. However, we detected CBZ and one of its metabolites in rain-fed wheat previously irrigated with treated wastewater, suggesting that their sorption was reversible, and indicating the potential for plant uptake and leaching. Finally, we used macroscale analyses (including adsorption/desorption trials and resin-based separations) with molecular- level characterization by FT-ICR MS to demonstrate the adsorptive fractionation of DOM from composted biosolids by mineral soil. This suggests that changes in soil and organic matter types will influence the extent of LTG and CBZ sorption to agricultural soils, as well as the potential for plant uptake and leaching.
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Chamovitz, A. Daniel, e Georg Jander. Genetic and biochemical analysis of glucosinolate breakdown: The effects of indole-3-carbinol on plant physiology and development. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7597917.bard.
Testo completoAbstract (sommario):
Genetic and biochemical analysis of glucosinolate breakdown: The effects of indole-3-carbinol on plant physiology and development Glucosinolates are a class of defense-related secondary metabolites found in all crucifers, including important oilseed and vegetable crops in the Brassica genus and the well-studied model plant Arabidopsis thaliana. Upon tissue damage, such as that provided by insect feeding, glucosinolates are subjected to catalysis and spontaneous degradation to form a variety of breakdown products. These breakdown products typically have a deterrent effect on generalist herbivores. Glucosinolate breakdown products also contribute to the anti-carcinogenic effects of eating cabbage, broccoli and related cruciferous vegetables. Indole-3-carbinol, a breakdown product of indol-3-ylmethylglucosinolate, forms conjugates with several other plant metabolites. Although some indole-3-carbinol conjugates have known functions in defense against herbivores and pathogens, most play as yet unidentified roles in plant metabolism, and possibly also plant development. At the outset, our proposal had three main hypotheses: (1) There is a specific detoxification pathway for indole-3-carbinol; (2) Metabolites derived from indole-3-carbinol are phloem-mobile and serve as signaling molecules; and (3) Indole-3-carbinol affects plant cell cycle and cell-differentiation pathways. The experiments were designed to enable us to elucidate how indole-3-carbinol and related metabolites affect plants and their interactions with herbivorous insects. We discovered that indole-3- carbinol rapidly and reversibly inhibits root elongation in a dose-dependent manner, and that this inhibition is accompanied by a loss of auxin activity in the root meristem. A direct interaction between indole-3-carbinol and the auxin perception machinery was suggested, as application of indole-3-carbinol rescued auxin-induced root phenotypes. In vitro and yeast-based protein interaction studies showed that indole-3-carbinol perturbs the auxin-dependent interaction of TIR1 with Aux/IAA proteins, supporting the notion that indole-3-carbinol acts as an auxin antagonist. Furthermore, transcript profiling experiments revealed the influence of indole-3-carbinol on auxin signaling in root tips, and indole-3-carbinol also affected auxin transporters. Brief treatment with indole-3-carbinol led to a reduction in the amount of PIN1 and to mislocalization of PIN2. The results indicate that chemicals induced by herbivory, such as indole-3-carbinol, function not only to repel herbivores, but also as signaling molecules that directly compete with auxin to fine tune plant growth and development, which implies transport of indole-3- carbinol that we are as yet unsuccessful in detecting. Our results indicate that plant defensive metabolites also have secondary functions in regulating aspects of plant metabolism, thereby providing diversity in defense-related plant signaling pathways. Such diversity of of signaling by defensive metabolites would be beneficial for the plant, as herbivores and pathogens would be less likely to mount effective countermeasures. We propose that growth arrest can be mediated directly by the herbivory-induced chemicals, in our case, indole-3-carbinol. Thus, glucosinolate breakdown to I3C following herbivory would have two outcomes: (1) Indole-3-carbinaol would inhibit the herbivore, while (2) at the same time inducing growth arrest within the plant. Thus, our results indicate that I3C is a defensive phytohormone that modulates auxin signaling, leading to growth arrest.
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Wackett, Lawrence, Raphi Mandelbaum e Michael Sadowsky. Bacterial Mineralization of Atrazine as a Model for Herbicide Biodegradation: Molecular and Applied Aspects. United States Department of Agriculture, gennaio 1999. http://dx.doi.org/10.32747/1999.7695835.bard.
Testo completoAbstract (sommario):
Atrazine is a broadly used herbicide in agriculture and it was used here as a model to study the biodegradation of herbicides. The bacterium Pseudomonas sp. ADP metabolizes atrazine to carbon dioxide and ammonia and chloride. The genes encoding atrazine catabolism to cyanuric acid were cloned and expressed in Escherichia coli. The genes were designated atzA, atzB and atzC. Each gene was sequenced. The enzyme activities were characterized. AtzA is atrazine chlorohydrolase which takes atrazine to hydroxyatrizine. AtzB is hydroxyatrazine N-ethylaminohydrolase which produces N-isopropylammelide and N-ethylamine. AtzC is N-isopropylammelide N-isopropylaminohydrolase which produces cyanuric acid and N-isopropylamine. Each product was isolated and characterized to confirm their identity by chromatography and mass spectrometry. Sequence analysis indicated that each of the hydrolytic enzymes AtzA, AtzB and AtzC share identity which the aminohydrolase protein superfamily. Atrazine chlorohydrolase was purified to homogeneity. It was shown to have a kcat of 11 s-1 and a KM of 150 uM. It was shown to require a metal ion, either Fe(II), Mn(II) or Co(II), for activity. The atzA, atzB and atzC genes were shown to reside on a broad-host range plasmid in Pseudomonas sp. ADP. Six other recently isolated atrazine-degrading bacteria obtained from Europe and the United States contained homologs to the atz genes identified in Pseudomonas sp. ADP. The identity of the sequences were very high, being greater than 98% in all pairwise comparisons. This indicates that many atrazine-degrading bacteria worldwide metabolize atrazine via a pathway that proceeds through hydroxyatrazine, a metabolite which is non-phytotoxic and non-toxic to mammals. Enzymes were immobilized and used for degradation of atrazine in aqueous phases. The in-depth understanding of the genomics and biochemistry of the atrazine mineralization pathway enabled us to study factors affecting the prevalence of atrazine degradation in various agricultural soils under conservative and new agricultural practices. Moreover, Pseudomonas sp. ADP and/or its enzymes were added to atrazine-contaminated soils, aquifers and industrial wastewater to increase the rate and extent of atrazine biodegradation above that of untreated environments. Our studies enhance the ability to control the fate of regularly introduced pesticides in agriculture, or to reduce the environmental impact of unintentional releases.
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Cytryn, Eddie, Mark R. Liles e Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, gennaio 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
Testo completoAbstract (sommario):
Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Schuster, Gadi, e David Stern. Integration of phosphorus and chloroplast mRNA metabolism through regulated ribonucleases. United States Department of Agriculture, agosto 2008. http://dx.doi.org/10.32747/2008.7695859.bard.
Testo completoAbstract (sommario):
New potential for engineering chloroplasts to express novel traits has stimulated research into relevant techniques and genetic processes, including plastid transformation and gene regulation. This proposal continued our long time BARD-funded collaboration research into mechanisms that influence chloroplast RNA accumulation, and thus gene expression. Previous work on cpRNA catabolism has elucidated a pathway initiated by endonucleolytic cleavage, followed by polyadenylation and exonucleolytic degradation. A major player in this process is the nucleus-encoded exoribonuclease/polymerasepolynucleotidephoshorylase (PNPase). Biochemical characterization of PNPase has revealed a modular structure that controls its RNA synthesis and degradation activities, which in turn are responsive to the phosphate (P) concentration. However, the in vivo roles and regulation of these opposing activities are poorly understood. The objectives of this project were to define how PNPase is controlled by P and nucleotides, using in vitro assays; To make use of both null and site-directed mutations in the PNPgene to study why PNPase appears to be required for photosynthesis; and to analyze plants defective in P sensing for effects on chloroplast gene expression, to address one aspect of how adaptation is integrated throughout the organism. Our new data show that P deprivation reduces cpRNA decay rates in vivo in a PNPasedependent manner, suggesting that PNPase is part of an organismal P limitation response chain that includes the chloroplast. As an essential component of macromolecules, P availability often limits plant growth, and particularly impacts photosynthesis. Although plants have evolved sophisticated scavenging mechanisms these have yet to be exploited, hence P is the most important fertilizer input for crop plants. cpRNA metabolism was found to be regulated by P concentrations through a global sensing pathway in which PNPase is a central player. In addition several additional discoveries were revealed during the course of this research program. The human mitochondria PNPase was explored and a possible role in maintaining mitochondria homeostasis was outlined. As polyadenylation was found to be a common mechanism that is present in almost all organisms, the few examples of organisms that metabolize RNA with no polyadenylation were analyzed and described. Our experiment shaded new insights into how nutrient stress signals affect yield by influencing photosynthesis and other chloroplast processes, suggesting strategies for improving agriculturally-important plants or plants with novel introduced traits. Our studies illuminated the poorly understood linkage of chloroplast gene expression to environmental influences other than light quality and quantity. Finely, our finding significantly advanced the knowledge about polyadenylation of RNA, the evolution of this process and its function in different organisms including bacteria, archaea, chloroplasts, mitochondria and the eukaryotic cell. These new insights into chloroplast gene regulation will ultimately support plant improvement for agriculture