RESUMEN
The enantioselective environmental behavior of difenoconazole, a widely utilized triazole fungicide commonly detected in agricultural soils, has yet to be comprehensively explored within the earthworm-soil system. To address this research gap, we investigated the bioaccumulation and elimination kinetics, degradation pathways, biotransformation mechanisms, spatial distribution, and toxicity of chiral difenoconazole. The four stereoisomers of difenoconazole were baseline separated and analyzed using SFC-MS/MS. Pronounced enantioselectivity was observed during the uptake phase, with earthworms exhibiting a preference for (2R,4R)-difenoconazole and (2R,4S)-difenoconazole. A total of five transformation products (TPs) were detected and identified using UHPLC-QTOF/MS in the earthworm-soil system. Four of the TPs were detected in both earthworm and soil, and one TP was produced only in eaerthwroms. Hydrolysis and hydroxylation were the primary transformation pathways of difenoconazole in both earthworms and soil. Furthermore, a chiral TP, 3-chloro, 4-hydroxy difenoconazole, was generated with significant enantioselectivity, and molecular docking results indicate the greater catalytic bioactivity of (2R,4R)- and (2R,4S)-difenoconazole, leading to the preferential formation of their corresponding hydroxylated TPs. Furthermore, Mass Spectrometry Imaging (MSI) was applied for the first time to explore the spatial distribution of difenoconazole and the TPs in earthworms, and the "secretory zone" was found to be the dominant region to uptake and biodegrade difenoconazole. ECOSAR predictions highlighted the potentially hazardous impact of most difenoconazole TPs on aquatic ecosystems. These findings are important for understanding the environmental fate of difenoconazole, evaluating environmental risks, and offering valuable insights for guiding scientific bioremediation efforts.
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Biotransformación , Dioxolanos , Fungicidas Industriales , Oligoquetos , Contaminantes del Suelo , Triazoles , Oligoquetos/metabolismo , Triazoles/metabolismo , Triazoles/química , Fungicidas Industriales/metabolismo , Fungicidas Industriales/química , Animales , Dioxolanos/metabolismo , Dioxolanos/química , Contaminantes del Suelo/metabolismo , Estereoisomerismo , Suelo/química , Espectrometría de Masas en Tándem , Biodegradación AmbientalRESUMEN
In this study, multi-residue analysis methods for 32 pyrethroids in fruit and vegetable samples were established in both GC-MS/MS and UHPLC-MS/MS. The parameters that affecting the ionization efficiencies of pyrethroids in UHPLC-ESI-MS/MS, including ion source temperature, in-source fragmentation, and mobile phase conditions were thoroughly investigated to guarantee better performance. These two techniques were comprehensively compared in terms of recovery, LOQ, linearity, and matrix effects. In general, UHPLC-MS/MS was found suitable for more pesticides than GC-MS/MS. Lower LOQs were obtained for most of the selected pyrethroids in UHPLC-MS/MS. Similar results were obtained in terms of recoveries and RSDs for the validated pesticides in fortification experiments. A total of 136 real samples were analyzed by both techniques, obtaining similar results. The results suggest that UHPLC-MS/MS offers a suitable alternative to GC-MS/MS in the routine analysis of pyrethroids in fruits and vegetables.
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Residuos de Plaguicidas , Plaguicidas , Piretrinas , Plaguicidas/análisis , Espectrometría de Masas en Tándem/métodos , Cromatografía Líquida de Alta Presión/métodos , Piretrinas/análisis , Verduras/química , Frutas/química , Cromatografía de Gases y Espectrometría de Masas , Residuos de Plaguicidas/análisisRESUMEN
Epoxiconazole is widely used in agriculture to control plant diseases; however, its effect on the nutritional quality of crops is poorly understood. In the present study, the stereoselective effects of epoxiconazole and its enantiomers on leek metabolites and lipids were clarified using metabolomics and lipidomics based on ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Multivariate analysis revealed significant differences in 123 compounds of leek exposed to chiral epoxiconazole compared to the control group. The order of the degree of influence was (+)-epoxiconazole > racemic-epoxiconazole>(-)-epoxiconazole, indicating significant stereoselectivity. The differential expression of metabolites indicated the activation of stress defense systems, including the antioxidant defense system and signaling pathways and phenylpropanoid metabolism. Alterations in the levels of compounds associated with nutritional quality, such as amino acids, vitamins, phenylpropanoids, flavonoids and lipids indicated changes in the nutritional quality of leek. In general, the nutritional quality of leek decreased after exposure to epoxiconazole.
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Lipidómica , Cebollas , Compuestos Epoxi , LípidosRESUMEN
>80 % of applied pesticides in agriculture will enter the soil and be exposed to soil animals. Little is known about the stereoselective metabolic effects of epoxiconazole (EPO) on soil animals. In this study, EPO-mediated stereoselective enrichment, biotransformation, oxidative stress, detoxification, and global metabolic profiles in earthworms were investigated by exposure to EPO and its enantiomers at 1 mg/kg and 10 mg/kg doses. Preferential enrichment of (-)-EPO was observed, and the five transformation products (TPs) exhibited the chemically specific stereoselective accumulation with inconsistent configurations. Biochemical markers related to reactive oxygen species (ROS) and detoxification (·OH- content, SOD, CAT, GST, and CYP450 enzymes) showed a significant stereoselective activation overall at the low-level exposure (p-value <0.05). Based on untargeted metabolomic analysis, the steroid biosynthesis and ROS-related biotransformation, glutathione metabolism, TCA cycle, amino acid metabolism, purine and pyrimidine metabolism of earthworms were significantly interfered with by EPO and its enantiomer exposure. More pronounced stereoselectivity was observed at the level of the global metabolic profile, while comparable levels of metabolic perturbations were identified at the individual metabolite level. This study provides novel insights into the stereoselective effects of the chiral fungicide EPO, and valuable evidence for soil environmental risk assessments.
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Fungicidas Industriales , Oligoquetos , Contaminantes del Suelo , Animales , Oligoquetos/metabolismo , Fungicidas Industriales/metabolismo , Contaminantes del Suelo/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Suelo/química , Estrés Oxidativo , BiotransformaciónRESUMEN
The environmental impact of the chiral fungicide epoxiconazole and its chiral transformation products (TPs) on non-target organisms and the environment has become a significant concern due to its widespread use in agricultural practice. Enantioselectivity studies of parent contaminants cannot adequately assess the complexity of its chiral TPs in the environment. This study aimed to investigate the environmental behavior of epoxiconazole in an earthworm-soil system. 2S,3R-(-)-epoxiconazole was preferentially enriched in earthworms during the accumulation phase (p < 0.05), but no enantioselectivity was observed during the elimination phase. One methoxylated and four hydroxylated chiral TPs were identified in soil, earthworm, and excrement. The epoxy ring hydroxylated TP and methoxylated TP of epoxiconazole were discovered for the first time in the environment. The chemically specific enantioselectivity with enantiomer fraction (EF) > 0.8 was observed for the TPs in different matrices. The CYP450 monooxygenase of earthworm was significant activated. In vitro enzyme metabolism experiments (earthworm microsomes and recombinant CYP450 enzymes CYP2A6, CYP 2C9, and CYP 3A4) were carried out to further explain the biotransformation mechanism of epoxiconazole in earthworm. This study provides new evidence of enantiomeric biotransformation of chiral fungicide epoxiconazole in the earthworm-soil system and could provide valuable insights into their environmental risk assessment.
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Fungicidas Industriales , Oligoquetos , Contaminantes del Suelo , Animales , Biotransformación , Compuestos Epoxi , Fungicidas Industriales/análisis , Suelo/química , Contaminantes del Suelo/análisis , Estereoisomerismo , TriazolesRESUMEN
The multiclass determination of antibiotic residues in the soil is challenging because of its complex physicochemical properties. In this study, a simple analytical method was developed to simultaneously extract and determine 58 antibiotics from the soil. A novel acidity-regulated extraction-partition-concentration protocol was established for the simultaneous extraction of five classes (23 sulfonamides, 18 quinolones, five tetracyclines, eight macrolides, and four chloramphenicols) of antibiotics from the soil. Compared to traditional methods, the sample preparation efficiency was significantly improved by four times (45 min vs. 230 min) by optimizing the extraction method and omitting the time-consuming solid-phase extraction (SPE) procedure. The ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was optimized to determine the 58 antibiotics in a single run by applying positive/negative switching acquisition mode in less than 10 min with the baseline separation of sulfameter and sulfamethoxypyridazine. Suitable recoveries, ranging between 60 and 120%, were obtained for most antibiotics, with RSD <20%. The limits of quantification (LOQ) of the method were 2 µg/kg and 5 µg/kg. Thus, this study provides a simple, reliable, and economical method for accurately and rapidly determining a multiclass of antibiotics in the soil.
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Macrólidos , Quinolonas , Antibacterianos/análisis , Cloranfenicol/análisis , Cromatografía Líquida de Alta Presión , Macrólidos/análisis , Quinolonas/análisis , Suelo/química , Extracción en Fase Sólida/métodos , Sulfonamidas/análisis , Espectrometría de Masas en Tándem/métodos , Tetraciclina , Tetraciclinas/análisisRESUMEN
The use of the chiral triazole fungicide cis-epoxiconazole in agricultural production continues to increase; however, little is known about the stereoselective and toxic responses of soil microorganisms to cis-epoxiconazole in the soil microenvironment. High-throughput sequencing and metabolomics were integrated to investigate the stereoselective response of soil microbial community structure, metabolic profile to cis-epoxiconazole exposure, and the correlation between the microbiomes and different metabolites. Soil microbial community structure and soil metabolic profile were significantly altered and exhibited significant enantioselectivity. The alpha diversity (Chao, Shannon, and Simpson diversity) of bacterial and fungus was not significantly affected, whereas the beta diversity (Bray-Curtis dissimilarity and PLS-DA) of bacterial and fungus was significantly altered in treatment of cis-epoxiconazole and its enantiomers (p-value < 0.05). The variation in bacterial and fungus community structure was the highest under (+)-enantiomer exposure, followed by exposure to racemate and (-)-enantiomer. Soil metabolomic analysis revealed that exposure to high or low doses of cis-epoxiconazole and its enantiomers resulted in different degrees of reprogramming of the soil metabolic pool. The 39 significantly changed metabolites mainly included small molecular organic acids, amino acids and their intermediates, and purine and adenosine intermediates. Six metabolic pathways were significantly disrupted. Different correlation patterns were observed between the significantly altered metabolites and microbes (p-value < 0.05) by Pearson correlation-based analysis. In conclusion, as xenobiotic pollutant, epoxiconazole altered the structure and metabolism of soil microorganisms with significant stereoselectivity mainly driven by 2R, 3S-(+)-cis-epoxiconazole. This study provided a more robust assessment of the risks of epoxiconazole exposure to soil microorganisms. Given the importance of the soil environment in agricultural production, characterization of the soil microbiome and metabolome can provide new insights into the ecological risks posed by exposure to the chiral triazole pesticide cis-epoxiconazole and its enantiomers.
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Fungicidas Industriales , Compuestos Epoxi , Fungicidas Industriales/análisis , Fungicidas Industriales/toxicidad , Secuenciación de Nucleótidos de Alto Rendimiento , Metabolómica/métodos , Suelo/química , Estereoisomerismo , Triazoles/químicaRESUMEN
In this study, non-targeted and targeted metabolomics/lipidomics studies based on UPLC-QTOF-MS and UPLC-MS/MS were carried out to clarify the effects of tebuconazole and its different enantiomers on lettuce metabolites and lipids. Slight enantioselective degradation of tebuconazole was observed and six degradation metabolites were tentatively identified. The endogenous metabolites involved in carbohydrate metabolism, amino acid metabolism, nucleic acid metabolism, phenylpropanoid and flavonoid metabolism, vitamins, and lipid metabolism were significantly affected with enantioselectivity by tebuconazole exposure. Nucleotide metabolism and nicotinic acid metabolic network were significantly activated by the stimulation of tebuconazole. Rac- and (-)-R-tebuconazole caused the down-regulation of soluble sugars and subsequent amino acids and organic acids. Overall, lettuce exposed to tebuconazole was shown to have a significant impact on plant metabolism and lipid metabolism, with notable stereoselectivity. The results showed stereoselective toxicity of tebuconazole and provided a better understanding of its metabolomic and lipidomic effects on lettuce.
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Fungicidas Industriales , Cromatografía Liquida , Fungicidas Industriales/análisis , Fungicidas Industriales/toxicidad , Lactuca , Lipidómica , Metabolómica , Espectrometría de Masas en Tándem , Triazoles/toxicidadRESUMEN
A sensitive and reliable method was developed and validated for the simultaneous determination of 49 amino acids, B vitamins, flavonoids, and phenolic acids based on a rapid metabolomic extraction procedure combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in a single chromatographic run and applied in analysis of 26 commonly consumed vegetables. The chromatographic and sample preparation conditions were optimized, given the high diversity of the target analytes. Eight isotope-labeled standards were applied to validate the method in terms of recovery, linearity, matrix effects, precision, and sensitivity. Most recoveries in four vegetable matrices ranged from 65.0% to 105.3% with associated RSDs < 20%. Low LOQs ranged from 0.06 to 17 µg/kg. Linear calibration curves with different ranges were established with R2 > 0.993. Among the 26 vegetables, purple cabbage, broccoli, and red lettuce were found to contain the highest concentrations of free amino acids, B vitamins, and phenolic compounds.
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Aminoácidos/análisis , Flavonoides/análisis , Análisis de los Alimentos/métodos , Hidroxibenzoatos/análisis , Verduras/química , Complejo Vitamínico B/análisis , Cromatografía Líquida de Alta Presión , Espectrometría de Masas en Tándem , Factores de TiempoRESUMEN
In this study, in-source fragmentation in ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) was investigated and applied for pesticide residue analysis. Over 400 pesticides were tested, among which 26 pesticides were found to be sensitive to in-source fragmentation, producing 33 in-source fragments. The fragment pathways were studied and severe in-source fragmentation was observed due to the cleavage of C-O bond of carbamate, phosphate, ester, and ether groups, especially for isocarbophos and methoprene, leading to false negative results. High source temperatures could significantly increase the extent of in-source fragmentation. A multiple reaction monitoring (MRM) based multiresidue method was established for the pesticide residue analysis in vegetables and fruits, applying both pesticides and in-source fragments as precursors. The quantification ability of the method was validated and compared in terms of recovery, linearity, and the limit of quantification. In-source fragmentswere found to be more suitable than their parent pesticides as precursor ions for MRM analysis.
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Cromatografía Líquida de Alta Presión , Análisis de los Alimentos/métodos , Contaminación de Alimentos/análisis , Residuos de Plaguicidas/análisis , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en Tándem , Frutas/química , Verduras/químicaRESUMEN
An unprecedented electrochemical trifluoromethylation/SO2 â insertion/cyclization process has been achieved in an undivided cell in an atom-economic fashion. The protocol relies on tandem cyclization of N-cyanamide alkenes by using Langlois' reagent as a source of both CF3 and SO2 under direct anodically oxidative conditions, in which two C-C bonds, two C-X bonds (N-S and S-C), and two rings were formed in a single operation. This transformation enabled efficient construction of various trifluoromethylated cyclic N-sulfonylimines from readily accessible materials.
RESUMEN
The ecotoxicity of perfluorooctane sulfonate (PFOS) is complex and has been reported in animals (including fish and mice), but the effects of PFOS in plants, especially the toxic mechanisms, have rarely been studied. High-throughput nontargeted metabolomics methods for comprehensive assessment were selected to study changes in metabolic characteristics in Arabidopsis thaliana leaves by exposure to different concentrations of PFOS throughout the growth period (30 days). All the metabolites were analyzed by PCA and OPLS-DA methods, by the cutoff of VIP and p-value, 53 biomarkers were found and significantly regulated, all amino acids except glutamate were inhibited and probably associated with binding to protein, auxin and cytokinin of phytohormones were significantly down-regulated. In response mechanism to oxidative stress from PFOS, the phenylpropanoid pathway were fully activated to form several polyphenols and further enhanced into several flavonoids against the reactive oxygen species (ROS) as the primary defend pathway, in addition, ascorbate, trehalose and nicotinamide also were activated and help decrease the damage from oxidative stress. These results provide insights into the mechanism underlying the phytotoxicity of PFOS.
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Arabidopsis , Metabolómica , Ácidos Alcanesulfónicos , Fluorocarburos , Hojas de la PlantaRESUMEN
In this work, a highly efficient pesticide residue screening and quantification method was established using ultrahigh-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry based on in-source fragmentation. Over 400 pesticides were tested, among which 96 pesticides displayed in-source fragmentation. A novel concept of in-source fragment fraction was proposed to evaluate the extent of in-source fragmentation, which was found to be chemical structure- and source parameter-dependent. A high-resolution MS/MS library containing 403 pesticides and 126 fragments was created and was applied for library searching of pesticide residues in vegetables and fruits. The introduction of in-source fragments effectively circumvented misannotation and occurrence of false negatives. The quantification ability for the fragments was validated in terms of recovery, linearity, and limit of quantification and its superiority to the parent pesticides was established. Finally, the proposed method was applied for the analysis of real samples and proficiency test samples, and false negative results were successfully avoided in the analysis.
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Cromatografía Líquida de Alta Presión/métodos , Frutas/química , Residuos de Plaguicidas/química , Espectrometría de Masas en Tándem/métodos , Verduras/química , Contaminación de Alimentos/análisis , Límite de DetecciónRESUMEN
The ecological toxicity of hexabromocyclododecane (HBCD) on animals, including fish and mice, has been reported, but its effects in plants, particularly its toxic mechanism, have rarely been investigated. An untargeted metabolomics approach for comprehensive assessment was selected to study the alterations in the metabolic profiles in pak choi leaves induced by exposure to trace-level amounts of HBCD diastereomers over 30 days. A supervised orthogonal partial least-squares-discriminant analysis (OPLS-DA) was performed to investigate differences between the HBCD and control groups. The discriminating metabolites were identified using public databases. The results indicated that the toxicity of the HBCD diastereomers was ordered as γ-HBCDâ¯>â¯α-HBCDâ¯>â¯ß-HBCD. 13 metabolites were identified as potential biomarkers to discriminate the presence of HBCD toxicity. The lipid, carbohydrate, nucleotide and amino acid metabolic pathways affected were found in accordance with animals and humans, and also HBCD could induce the interference of the secondary metabolite pathways. The system of the stress defences was activated, including signalling pathway, antioxidant defence system, shikimate and phenylpropanoid metabolism. The carbohydrate and amino acid metabolism were disturbed by HBCD intervention, and the lipid, amino acid and secondary metabolite metabolism were regulated for HBCD stress prevention. These results provide insights into the mechanism and degree of HBCD phytotoxicity.
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Brassica rapa/química , Hidrocarburos Bromados/toxicidad , Metaboloma/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Aminoácidos/metabolismo , Animales , Antioxidantes , Brassica rapa/fisiología , Peces/metabolismo , Humanos , Redes y Vías Metabólicas , Metabolómica/métodos , RatonesRESUMEN
The chiral signatures and environmental behaviors of chiral polychlorinated biphenyls (PCBs) have been extensively studied. However, information regarding chiral PCBs in invertebrates, especially earthworms, is limited. This study aimed to investigate the stereoselective bioaccumulation, elimination, and biotransformation of chiral PCBs 95 and 149 in an earthworm-soil system. Preferential enrichment of (+)-atropisomers and elimination of (-)-atropisomers were observed, for both PCBs 95 and 149, during the uptake and elimination phases, respectively, leading to higher enantiomer fractions (EFs). A significant linear correlation between the total concentrations of chiral PCBs and EF values was found in earthworms. The EF values increased with the increase in exposure time and further increased during the elimination phase, indicating the biotransformation of chiral PCBs. Hydroxylated metabolites of PCB 95 were found in earthworms for the first time, thus verifying the ability of earthworms to metabolize chiral PCBs. However, no methylsulfonyl metabolites were observed for PCBs 95 and 149. These findings might be helpful for understanding the biological processes of chiral PCBs in species at lower trophic levels.
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Bifenilos Policlorados/química , Animales , Oligoquetos , EstereoisomerismoRESUMEN
Stereoselective bioaccumulation, elimination, metabolomic and lipidomic responses of earthworm Eisenia fetida exposed to chiral polychlorinated biphenyl (PCB) 91 in an earthworm-soil system were investigated. Preferential bioaccumulation of (-)-PCB 91 and elimination of (+)-PCB 91 were observed following 50 and 500 µg/kgdwt exposures. Enantiomer fraction (EF) values decreased over time during the uptake and elimination periods. Metabolomics and lipidomics techniques based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) revealed significant changes in 108 metabolites after earthworms exposure to (+)-, (-)-, and (±)-PCB 91, compared to control groups. Forty two of these metabolites were identified as amino acids, nucleosides, fatty acids, dicarboxylic acids, vitamins or others. Lysophospholipids including six lysophosphatidylcholines (LPC), six lysophosphatidylethanolamine (LPE), eight lysophosphatidylinositol (LPI) and five lysophosphatidylserine (LPS) were also differentially expressed between exposure and control groups. Alterations in the levels of metabolites and lipids indicated stereoselective effects of chiral PCB 91 on earthworm amino acid, energy, and nucleotide metabolism, neurodevelopment and gene expression. Overall, the effects of (+)-PCB 91 were more pronounced than that of (-)- and (±)-PCB 91.
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Oligoquetos/metabolismo , Bifenilos Policlorados/metabolismo , Contaminantes del Suelo/metabolismo , Animales , Cromatografía Liquida , Metaboloma/fisiología , Metabolómica , Suelo/química , Contaminantes del Suelo/química , Estereoisomerismo , Espectrometría de Masas en TándemRESUMEN
BACKGROUND: The dissipation behavior, pre-harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites were investigated in greenhouse cucumber in Tianjin, northern China, to ensure raw consumption safety. RESULTS: Carbosulfan was metabolized to carbofuran, dibutylamine, 3-hydroxycarbofuran and 3-ketocarbofuran, and dimethoate was degraded to omethoate in cucumber fruits and leaves. The dissipation of carbosulfan, carbofuran, 3-hydroxycarbofuran and dimethoate fitted first-order kinetics well, with R2 ranging from 0.912 to 0.992, and their half-lives were 2.6, 2.7, 2.4 and 5.2 days in cucumber fruits and 2.8, 3.0, 4.6 and 2.5 days in leaves, respectively. The estimated daily intakes of the active ingredients and their relevant metabolites were 0.1-4% of the corresponding acceptable daily intakes. Acute oral exposure to carbofuran (a metabolite of carbosulfan) represented 367% of the acute reference dose (ARfD) for 1-6-year-old Chinese children and 227% for the general Chinese population. CONCLUSION: A minimum pre-harvest interval of 12 days for carbosulfan is proposed to ensure safe consumption of cucumber. The slow dissipation rate of omethoate in cucumber reveals that a longer pre-harvest interval (≥ 27 days) is necessary to prevent dietary risk when dimethoate is applied to cucumber. © 2018 Society of Chemical Industry.
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Carbamatos/metabolismo , Cucumis sativus , Dimetoato/metabolismo , Insecticidas/metabolismo , Residuos de Plaguicidas/análisis , Frutas/química , Humanos , Medición de Riesgo , Factores de TiempoRESUMEN
Bacillus subtilis responds to environmental stress cues and develops endospores for survival. In the process of endospore formation, sporulation initiation is a vital stage and this stage is governed by autophosphorylation of the sensor histidine kinases. The second major sensor kinase KinB perceives the intracellular changes of GTP and ATP during sporulation. However, determination of the environmental signals as well as its related signaling pathway of KinB requires further elucidation. Our current study found that, contrary to the sporulation failure induced by ΔkinA in the nutrient-rich 2× SG medium, the sensor kinase KinB sensed the environmental cues in the nutrient-poor MM medium. Two other membrane proteins, KapB and KbaA, also responded similarly to the same external signal as KinB. Both KapB and KbaA acted upstream of KinB, but they exerted their regulation upon KinB independently. Furthermore, we demonstrated that both the SH3 domain and the α-helix structure in KapB are required for sensing or transducing the signal of sporulation initiation. Collectively, our work here supplied the direct evidences that KinB and its pathway sense the external signal of nutrient starvation in MM medium, and further analyzes the interrelationship among KinB, KbaA, and KapB.
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Bacillus subtilis/enzimología , Bacillus subtilis/crecimiento & desarrollo , Proteínas Bacterianas/metabolismo , Metabolismo , Fosfotransferasas/metabolismo , Transducción de Señal , Esporas Bacterianas/enzimología , Esporas Bacterianas/crecimiento & desarrollo , Adenosina Trifosfato/metabolismo , Medios de Cultivo/química , Guanosina Trifosfato/metabolismo , Proteínas Ligadas a Lípidos/metabolismo , Proteínas de la Membrana/metabolismo , Estrés FisiológicoRESUMEN
In this research, the manual two-step QuEChERS approach has been streamlined and automated into a one-step method using a cleanup tube fitted within an extraction tube. A novel automatic QuEChERS combination have been developed to simplify the QuEChERS procedures and improve sample preparation efficiency. This combination integrates QuEChERS procedures into a single run via the use of a vortex vibration-centrifuge device and a centrifuge filtration tube. To validate the efficiency of our automatic QuEChERS device, 270 pesticides were analyzed in plant origined foods including celery, tomatoes, leeks, eggplants, grapes, corn, green tea, and soybean oil using this automatic platform. The results were then compared with those obtained using the manual QuEChERS method. Different parameters were validated and compared including recovery, linearity, repeatability and limits of quantification (LOQ). Satisfactory results, comparable to results obtained using the manual QuEChERS method were obtained. The average recoveries ranged between 70% and 120% for most pesticides with associated relative standard deviations (RSDs) <20% (n=5) indicating satisfactory accuracy and repeatability. An LOQ of 2µg/kg was obtained for most pesticides present in celery and corn matrices, and the correlation coefficients (r2) were >0.990 within a linearity range of 2-500µg/kg. Compared to manual QuEChERS, this novel automatic QuEChERS device and combination could significantly improve the sample preparation efficiency for the multiresidue analysis of pesticides.
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Análisis de los Alimentos/métodos , Residuos de Plaguicidas/análisis , Análisis de los Alimentos/economía , Análisis de los Alimentos/normas , Límite de Detección , Reproducibilidad de los Resultados , Manejo de EspecímenesRESUMEN
The increasing use of antibiotics has caused substantial environmental problems, which are a matter of great concern. The aim of this work was to develop a quick, easy, cheap, effective, rugged, and safe method for 20 antibiotic residues in soil. The developed method is based on extraction with acetonitrile and phosphate buffer, clean up with dispersive solid-phase extraction adsorbent using primary secondary amine, octadecylsilane, followed by liquid chromatography with tandem mass spectrometry determination. We optimized different extraction methods and the ratio of cleanup adsorbents to achieve good recoveries at seven spiking levels that ranged from 61.4 to 118.9% with a relative standard deviation below 20% (n = 5). The method quantification limit was in the range of 2-5 µg/kg for most analytes. Good linear regression coefficients greater than 0.990 were obtained. This method was applied for the analysis of real agricultural soil samples, confirming the feasibility of the method.