Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 139
Filtrar
1.
Nature ; 568(7751): 259-263, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30944473

RESUMO

The genetic compensation response (GCR) has recently been proposed as a possible explanation for the phenotypic discrepancies between gene-knockout and gene-knockdown1,2; however, the underlying molecular mechanism of the GCR remains uncharacterized. Here, using zebrafish knockdown and knockout models of the capn3a and nid1a genes, we show that mRNA bearing a premature termination codon (PTC) promptly triggers a GCR that involves Upf3a and components of the COMPASS complex. Unlike capn3a-knockdown embryos, which have small livers, and nid1a-knockdown embryos, which have short body lengths2, capn3a-null and nid1a-null mutants appear normal. These phenotypic differences have been attributed to the upregulation of other genes in the same families. By analysing six uniquely designed transgenes, we demonstrate that the GCR is dependent on both the presence of a PTC and the nucleotide sequence of the transgene mRNA, which is homologous to the compensatory endogenous genes. We show that upf3a (a member of the nonsense-mediated mRNA decay pathway) and components of the COMPASS complex including wdr5 function in GCR. Furthermore, we demonstrate that the GCR is accompanied by an enhancement of histone H3 Lys4 trimethylation (H3K4me3) at the transcription start site regions of the compensatory genes. These findings provide a potential mechanistic basis for the GCR, and may help lead to the development of therapeutic strategies that treat missense mutations associated with genetic disorders by either creating a PTC in the mutated gene or introducing a transgene containing a PTC to trigger a GCR.


Assuntos
Códon sem Sentido/genética , Teste de Complementação Genética , Complexos Multiproteicos/metabolismo , RNA Mensageiro/genética , Peixe-Zebra/genética , Animais , Proteínas de Ligação ao Cálcio/deficiência , Proteínas de Ligação ao Cálcio/genética , Deleção de Genes , Células HCT116 , Histonas/metabolismo , Humanos , Complexos Multiproteicos/química , Degradação do RNAm Mediada por Códon sem Sentido , Organismos Geneticamente Modificados , Proteínas de Peixe-Zebra/deficiência , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
2.
Pestic Biochem Physiol ; 201: 105888, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38685219

RESUMO

Bemisia tabaci is a formidable insect pest worldwide, and it exhibits significant resistance to various insecticides. Dimpropyridaz is a novel pyridazine pyrazolecarboxamide insecticide used against sucking insect pests, but there is little information regarding its metabolic detoxification in arthropods or cross-resistance with other insecticides. In this study, we found that dimpropyridaz shows no cross-resistance with three other popular insecticides, namely abamectin, cyantraniliprole, and flupyradifurone. After treatment of B. tabaci adults with a high dose of dimpropyridaz, higher cytochrome P450 monooxygenase (P450) activity was detected in the survivors, and the expression of the P450 gene CYP6DW4 was highly induced. Cloning and characterization of the full-length amino acid sequence of CYP6DW4 indicated that it contains conserved domains typical of P450 genes, phylogenetic analysis revealed that it was closely related to a B. tabaci protein, CYP6DW3, known to be involved in detoxification of imidacloprid. Silencing of CYP6DW4 by feeding insects with dsRNA significantly increased the susceptibility of B. tabaci to dimpropyridaz. In addition, homology modeling and molecular docking analyses showed the stable binding of dimpropyridaz to CYP6DW4, with binding free energy of -6.65 kcal/mol. Our findings indicate that CYP6DW4 plays an important role in detoxification of dimpropyridaz and possibly promotes development of resistance in B. tabaci.


Assuntos
Sistema Enzimático do Citocromo P-450 , Hemípteros , Proteínas de Insetos , Resistência a Inseticidas , Inseticidas , Ivermectina/análogos & derivados , Pirazóis , Piridazinas , ortoaminobenzoatos , Animais , Hemípteros/efeitos dos fármacos , Hemípteros/genética , Inseticidas/farmacologia , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Piridazinas/farmacologia , Resistência a Inseticidas/genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteínas de Insetos/química , Pirazóis/farmacologia , Filogenia , Neonicotinoides/farmacologia , Técnicas de Silenciamento de Genes , Simulação de Acoplamento Molecular , Sequência de Aminoácidos , Ivermectina/farmacologia , Ivermectina/toxicidade
3.
Molecules ; 29(3)2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38338425

RESUMO

Organophosphorus flame retardants (OPFRs) have been widely used in polymeric materials owing to their flame retardant and plasticizing effects. Investigating the fragmentation pathway of OPFRs is of great necessity for further discovering and identifying novel pollutants using orbitrap-based high-resolution mass spectrometry (HRMS). A total of 25 OPFRs, including alkyl, halogenated, and aromatic types, were analyzed in this study. The fragmentation pathways of the OPFRs were investigated using orbitrap-based HRMS with high-energy collision dissociation (HCD) in positive mode. The major fragmentation pathways for the three types of OPFRs are greatly affected by the substituents. In detail, the alkyl and halogenated OPFRs underwent three McLafferty hydrogen rearrangements, wherein the substituents were gradually cleaved to form the structurally stable [H4PO4]+ (m/z = 98.9845) ions. In contrast, the aromatic OPFRs would cleave not only the C-O bond but also the P-O bond, depending on the substituents, to form fragment ions such as [C6H7O]+ (m/z = 95.0495) or [C7H7]+ (m/z = 91.0530), among others. Using HRMS improved the accuracy of fragment ion identification, and the pathway became more evident. These fragmentation laws can provide identification information in pollutant screening work and theoretical references for the structural characterization of compounds with diverse substituent structures.

4.
Molecules ; 29(9)2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38731466

RESUMO

Tripropyl phosphate (TnPP) is a commonly used organic phosphate flame retardant in the textiles, plastics, and coating industries. Residues are commonly detected in samples from the environment and food. The availability of certified reference materials (CRMs) is essential to ensure the accuracy and traceability of detection results. In this study, a comprehensive characterization of a CRM for TnPP was carried out, and its purity was evaluated using two distinct methodologies: mass balance (MB) and quantitative nuclear magnetic resonance spectroscopy (qNMR). In the MB method, the levels of structurally related organic impurities are 1.37 mg/g. The water content was determined to be 3.16 mg/g, while inorganic impurities were found to be 0.87 mg/g, and no residual organic solvents were detected. Benzoic acid and monocrotophos were chosen as internal standards for 1H-qNMR and 31P-qNMR, respectively. The purity of the TnPP CRM was assessed as 994.6 mg/g, 994.1 mg/g, and 993.5 mg/g using MB, 1H-qNMR, and 31P-qNMR techniques, respectively. The verified purity of the TnPP CRM was ultimately determined to be 994.1 mg/g, with an expanded uncertainty of 3.4 mg/g (k = 2), ensuring traceability to the International System of Units (SI). This CRM can be effectively utilized for preparing calibration solutions suitable for the routine monitoring of TnPP residues in plastics and food samples.

5.
Proc Natl Acad Sci U S A ; 117(28): 16193-16198, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601186

RESUMO

A distinct class of aurora, called transpolar auroral arc (TPA) (in some cases called "theta" aurora), appears in the extremely high-latitude ionosphere of the Earth when interplanetary magnetic field (IMF) is northward. The formation and evolution of TPA offers clues about processes transferring energy and momentum from the solar wind to the magnetosphere and ionosphere during a northward IMF. However, their formation mechanisms remain poorly understood and controversial. We report a mechanism identified from multiple-instrument observations of unusually bright, multiple TPAs and simulations from a high-resolution three-dimensional (3D) global MagnetoHydroDynamics (MHD) model. The observations and simulations show an excellent agreement and reveal that these multiple TPAs are generated by precipitating energetic magnetospheric electrons within field-aligned current (FAC) sheets. These FAC sheets are generated by multiple-flow shear sheets in both the magnetospheric boundary produced by Kelvin-Helmholtz instability between supersonic solar wind flow and magnetosphere plasma, and the plasma sheet generated by the interactions between the enhanced earthward plasma flows from the distant tail (less than -100 RE) and the enhanced tailward flows from the near tail (about -20 RE). The study offers insight into the complex solar wind-magnetosphere-ionosphere coupling processes under a northward IMF condition, and it challenges existing paradigms of the dynamics of the Earth's magnetosphere.

6.
Int J Mol Sci ; 24(6)2023 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-36982427

RESUMO

Spodoptera litura is a damaging and notorious insect pest of agricultural crops that has developed resistance to various insecticides. Broflanilide is a novel pesticide with a unique mode of action that displays high efficiency against lepidopterous larvae. We here determined the baseline susceptibility of a laboratory strain of S. litura to broflanilide and 10 other popular insecticides. Furthermore, we measured susceptibility and cross-resistance using three common insecticides in 11 field-collected S. litura populations. Broflanilide caused the highest toxicity among all tested insecticides, with the laboratory strain and all field-collected populations showing high susceptibility. Moreover, no cross-resistance was detected between broflanilide and the other tested insecticides. We subsequently evaluated the sublethal effects of broflanilide and found that treatment with the 25% lethal concentration (LC25) prolonged the development duration in the larvae, reduced the pupation rate and pupae weight, and decreased egg hatchability. Finally, the activities of three detoxifying enzymes were measured in S. litura after treatment with the LC25 dose. The results suggested that enhanced cytochrome P450 monooxygenase (P450) activity could be involved in broflanilide detoxification. Overall, these findings demonstrate the strong toxicity and significant sublethal effects of broflanilide in S. litura and suggest that increased P450 activity may be associated with broflanilide detoxification.


Assuntos
Inseticidas , Praguicidas , Animais , Praguicidas/farmacologia , Inseticidas/toxicidade , Spodoptera , Diamida/farmacologia , Larva
7.
Opt Express ; 30(21): 38764-38775, 2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36258434

RESUMO

A linear-to-linear polarization conversion metamaterial is proposed with a water-metal structure. The simulation results show that the proposed metamaterial design can achieve ultra-broadband and high-efficiency polarization conversion within the frequency range from 7.46 GHz to 14.84 GHz with a polarization conversion ratio over 90%. This metamaterial exhibits sensitivity to the incidence angle but not to and temperature. The physical mechanism of polarization conversion is analyzed based on the distributions of the surface current and the magnetic field. An experimental sample of the designed metamaterial is fabricated, assembled, and measured in such a way as to realize reflective polarization conversion. This work provides a significant stepping stone for water-based metamaterial design and polarization control.

8.
Opt Express ; 30(14): 24874-24888, 2022 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-36237031

RESUMO

Microstructure surfaces are widely and deeply applied in optical fields to decrease the volume of an optical system and realize sophisticated optical requirements. This paper studies the machining of optical micro-structures with micro-scale height on single crystal germanium by elliptical vibration assisted sculpturing (EVAS) method in which two vibration amplitudes keep constant. Due to the superimposition of low-frequency sculpture path and high-frequency elliptical locus, the investigations are focused on cutting plane to describe motion trajectory of the tool tip of cutting tool for desired complex motion path and to calculate the sculpture path of elliptical vibration cutting device to make corresponding path of tool tip be the envelope of target profile. A comparative experiment is firstly conducted to verify that elliptical locus would deteriorate machining accuracy without accurate compensation for the ellipse. Following that, 2D and 3D sinusoidal surfaces and a picture, whose structural heights are all not less than 2.0µm, are experimentally machined on single crystal germanium. Satisfying experimental results demonstrate the feasibility of EVAS method for fabricating optical micro-structures on germanium.

9.
Crit Rev Food Sci Nutr ; 62(20): 5444-5461, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33583259

RESUMO

Ochratoxin A is a highly toxic mycotoxin and has posed great threat to human health. Due to its serious toxicity and wide contamination, great efforts have been made to develop reliable determination methods. In this review, analytical methods are comprehensively summarized in terms of sample preparation strategy and instrumental analysis. Detailed method is described according to the food commodities in the order of cereal, wine, coffee, beer, cocoa, dried fruit and spice. This review mainly focuses on the recent advances, especially reported in the last decade. At last, challenges and perspectives are also discussed to achieve better advancement and promote practical application in this field.


Assuntos
Contaminação de Alimentos , Ocratoxinas , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Humanos , Espectrometria de Massas
10.
Anal Bioanal Chem ; 414(12): 3631-3641, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35305116

RESUMO

In this study, a trans-zearalenone (trans-ZEN) calibrant in acetonitrile as certified reference material (CRM) was prepared and intensively investigated the stability by high performance liquid chromatography coupled diode array detection and triple quadrupole tandem mass spectrometry (HPLC-DAD-MS/MS). The photoisomerization and degradation of main component and related impurities in trans-ZEN calibrant CRM was studied in detail under different light conditions such as UV light (254 nm), sunlight, and visible light. Trans-ZEN in acetonitrile was confirmed a significant shift toward cis-ZEN up to a 52% cis-isomerization rate after exposing to UV light (254 nm) in transparent ampule for 1 day. The unsaturated double bond photosensitive groups of trans-ZEN and cis-ZEN will further undergo photoreaction to generate more isomers and related products with the increase of UV irradiation time. The calibrant in amber ampules was relatively stable after exposing to sunlight for 28 days, with only 0.35% cis-isomer observed. The results indicated that trans-ZEN solution calibrant should be packed in amber ampules to avoid UV rays. Thermal stability test exhibited this calibrant was stable over 6 weeks even at 60 °C. Trans-ZEN was found to be more stable in acetonitrile than in methanol since an unknown impurity was observed in methanol after 6 weeks placed at 25 °C. The stability study of trans-ZEN calibrant provided a basis for the usage, storage, and transportation of the CRM. A concentration and expanded uncertainty of the trans-ZEN calibrant CRM of 11.01 ± 0.18 µg/mL was developed.


Assuntos
Zearalenona , Âmbar , Cromatografia Líquida de Alta Pressão/métodos , Metanol , Espectrometria de Massas em Tandem/métodos , Zearalenona/análise
11.
Anal Bioanal Chem ; 414(24): 7203-7210, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35972524

RESUMO

Thiamethoxam (TMX) is a widely used neonicotinoid insecticide in pest control. Identification of structurally related impurities is very important during certified reference material development and pesticide registration, thus it needs to be carefully characterized. In this study, a combined strategy with liquid chromatography-high resolution mass spectrometry and computer assisted elucidation (SIRIUS) has been developed for the impurity elucidation in TMX material. MS and MS/MS spectra were used to score the impurity candidates by isotope score and fragment tree in SIRIUS. TMX, the main component, worked as an anchor for formula identification and structure elucidation of impurity. With this strategy, four impurities were identified, including two byproducts (TMX-OCH3 and TMX-Cl) and two metabolites (clothianidin and TMX-urea). Their fragmentation pathways were concluded, and mechanism of impurity formation was also proposed. This result showed successful application of combining human intelligence with machine learning in impurity identification from chemicals.


Assuntos
Inseticidas , Praguicidas , Cromatografia Líquida de Alta Pressão/métodos , Computadores , Humanos , Inseticidas/química , Neonicotinoides , Espectrometria de Massas em Tandem/métodos , Tiametoxam , Ureia
12.
BMC Vet Res ; 18(1): 240, 2022 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-35751066

RESUMO

BACKGROUND: Pullorum disease caused by Salmonella pullorum is one of the most important infectious diseases in the poultry industry, responsible for causing substantial economic losses globally. On farms, the traditional method to detect S. pullorum infection mainly involves the collection of feces and sera to test for antigens and antibodies, respectively, but the regularity of Salmonella pullorum dissemination in internal organs and shedding patterns and antibody production in infected chickens remains unclear. Herein we aimed to investigate the dissemination of S. pullorum to different organs and bacterial shedding patterns in the faeces as well as serum antibody production post-infection in chickens of different ages. RESULT: In this study, the liver and heart of 2-day-old chickens showed the highest copy numbers of S. pullorum at 6.4 × 106 and 1.9 × 106 copies of DNA target sequences/30 mg, respectively. In case of 10-day-old chickens, the percentage of S. pullorum fecal shedding (0%-40%) and antibody production (0%-56.6%) markedly fluctuated during the entire experiment; furthermore, in case of 42-week-old chickens, the percentage of birds showing S. pullorum shedding in the faeces showed a downward trend (from 63.33% to 6.6% in the oral inoculation group and from 43.3% to 10% in the intraperitoneal injection group), while that of birds showing serum antibody production remained at a high level (38.3% and 80% in the oral inoculation and intraperitoneal injection groups, respectively). We also performed cohabitation experiments, showed that 15% 10-day-old and 3.33% 42-week-old chickens were infected via the horizontal transmission in cohabitation with S. pullorum infected chickens, and revealed a high risk of horizontal transmission of S. pullorum. CONCLUSION: This study systematically evaluated the dissemination of S. pullorum in internal organs and bacterial fecal shedding patterns, and antibody production in infected chickens. Collectively, our findings indicate how to effectively screen S. pullorum-negative chickens on livestock farms and should also help in the development of measures to control and eradicate S. pullorum.


Assuntos
Doenças das Aves Domésticas , Salmonelose Animal , Animais , Formação de Anticorpos , Galinhas/microbiologia , Doenças das Aves Domésticas/microbiologia , Salmonella , Salmonelose Animal/microbiologia
13.
Sensors (Basel) ; 22(11)2022 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-35684902

RESUMO

Electrostatic probe diagnosis is the main method of plasma diagnosis. However, the traditional diagnosis theory is affected by many factors, and it is difficult to obtain accurate diagnosis results. In this study, a long short-term memory (LSTM) approach is used for plasma probe diagnosis to derive electron density (Ne) and temperature (Te) more accurately and quickly. The LSTM network uses the data collected by Langmuir probes as input to eliminate the influence of the discharge device on the diagnosis that can be applied to a variety of discharge environments and even space ionospheric diagnosis. In the high-vacuum gas discharge environment, the Langmuir probe is used to obtain current-voltage (I-V) characteristic curves under different Ne and Te. A part of the data input network is selected for training, the other part of the data is used as the test set to test the network, and the parameters are adjusted to make the network obtain better prediction results. Two indexes, namely, mean squared error (MSE) and mean absolute percentage error (MAPE), are evaluated to calculate the prediction accuracy. The results show that using LSTM to diagnose plasma can reduce the impact of probe surface contamination on the traditional diagnosis methods and can accurately diagnose the underdense plasma. In addition, compared with Te, the Ne diagnosis result output by LSTM is more accurate.


Assuntos
Memória de Curto Prazo , Redes Neurais de Computação , Memória de Longo Prazo , Temperatura
14.
Sensors (Basel) ; 22(17)2022 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-36080779

RESUMO

Intelligent monitoring and early warning of rock mass failure is vital. To realize the early intelligent identification of dynamic fractures in the failure process of complex fractured rocks, 3D printing of the fracture network model was used to produce rock-like specimens containing 20 random joints. An algorithm for the early intelligent identification of dynamic fractures was proposed based on the YOLOv5 deep learning network model and DIC cloud. The results demonstrate an important relationship between the overall strength of the specimen with complex fractures and dynamic fracture propagation, and the overall specimen strength can be judged semi-quantitatively by counting dynamic fracture propagation. Before the initiation of each primary fracture, a strain concentration area appears, which indicates new fracture initiation. The dynamic evolution of primary fractures can be divided into four types: primary fractures, stress concentration areas, new fractures, and cross fractures. The cross fractures have the greatest impact on the overall strength of the specimen. The overall identification accuracy of the four types of fractures identified by the algorithm reached 88%, which shows that the method is fast, accurate, and effective for fracture identification and location, and classification of complex fractured rock masses.


Assuntos
Fraturas Ósseas , Algoritmos , Humanos
15.
Int J Mol Sci ; 23(18)2022 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-36142377

RESUMO

Bemisia tabaci is a threat to agriculture worldwide because of its potential to cause devastating damage to various crops. ß-asarone is a bioactive pesticidal chemical originating from Acorus calamus (or "Sweet Flag") plants, and it displays significant lethal effects against insect pests. In this study, we established a baseline of susceptibility to ß-asarone from China and patterns of cross-resistance to other popular insecticides. We found that all the 12 field-collected B. tabaci populations exhibited high susceptibility to ß-asarone, and there was no cross-resistance detected for other tested insecticides. We subsequently evaluated the sublethal effects of ß-asarone on physiology and biochemistry via LC25 treatment (4.7 mg/L). LC25 of ß-asarone resulted in prolonged developmental duration and decreased survival rates in B. tabaci nymphs, pseudopupae, and adults. Significant reductions in oviposition duration, fecundity, and hatchability were also observed. Additionally, the metabolic enzyme activity and expression profiles of selected cytochrome P450 monooxygenase (P450) genes following the LC25 treatment of ß-asarone suggest that enhanced detoxification via P450s could be involved in the observed sublethal effects. These findings demonstrate the strong toxicity and significant sublethal effects of ß-asarone on B. tabaci and suggest that the induced overexpression of P450 genes could be associated with the response to ß-asarone.


Assuntos
Derivados de Alilbenzenos , Hemípteros , Inseticidas , Animais , Anisóis , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Hemípteros/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia
16.
Molecules ; 27(16)2022 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-36014490

RESUMO

Dinotefuran (DNT) is a neonicotinoid insecticide widely used in pest control. Identification of structurally related impurities is indispensable during material purification and pesticide registration and certified reference material development, and therefore needs to be carefully characterized. In this study, a combined strategy with liquid chromatography high-resolution mass spectrometry and SIRIUS has been developed to elucidate impurities from DNT material. MS and MS/MS spectra were used to score the impurity candidates by isotope score and fragment tree in the computer assisted tool, SIRIUS. DNT, the main component, worked as an anchor for formula identification and impurity structure elucidation. With this strategy, two by-product impurities and one stereoisomer were identified. Their fragmentation pathways were concluded, and the mechanism for impurity formation was also proposed. This result showed a successful application for combined human intelligence and machine learning, in the identification of pesticide impurities.


Assuntos
Praguicidas , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Medicamentos , Guanidinas , Humanos , Neonicotinoides , Nitrocompostos , Espectrometria de Massas em Tandem/métodos
17.
Anal Chem ; 93(44): 14837-14843, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34714065

RESUMO

Accurately quantifying chemical additives with adverse health effects in plastic products is critical for environmental safety and risk assessment. In this work, a novel approach using solubility parameters (δ) as indicators for the extraction of additives in plastics was developed. The mechanism was evaluated by using 10 organic solvents with different solubility parameters to extract brominated flame-retardant-decabrominated diphenyl ether (BDE-209) in polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Certified reference materials (CRMs) or CRM candidate materials were applied as matrix materials. The extracted BDE-209 and solubility parameters of solvents could fit into a curve of a quadratic function. The value of abscissa corresponding to the vertex of the function was close to the solubility parameter of plastic calculated by the group contribution method (Δδ < 0.37). Toluene, n-hexane, and acetone were the solvents with high extraction efficiency for PE, PP, and PET, confirming the feasibility of the developed approach. The results of ethyl acetate and acetone indicated the high weight of functional groups affecting the dissolution behavior. The developed approach was further verified by analyzing penta-/octa-BDE and phthalate esters in PET and polyvinyl chloride (PVC) and finally applied to analyze 15 plastic products made of PP, PE, PET, polystyrene, and PVC. The detected tetrabromodiphenyl ether (BDE-47), BDE-209, decabromodiphenyl ethane, and di(2-ethylhexyl) terephthalate all matched the approach and verified its practicability for field sample analysis.


Assuntos
Plásticos , Polipropilenos , Poliestirenos , Cloreto de Polivinila , Solubilidade
18.
Pestic Biochem Physiol ; 171: 104744, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33357566

RESUMO

The sweetpotato whitefly Bemisia tabaci is a polyphagous crop pest distributed worldwide and frequent exposure to many different defensive secondary metabolites in its host plants. To counteract these defensive plant secondary metabolites, B. tabaci elevate their production of detoxification enzymes, including cytochrome P450 monooxygenases. Besides their tolerance to phytotoxin, B. tabaci have quickly developed resistance to various insecticides in the field. However, the relationship between host plant secondary metabolites and insecticide resistance in B. tabaci is not fully understood. In this study, the influence of plant flavonoid ingestion on B. tabaci tolerance to thiamethoxam and flupyradifurone insecticides and its possible mechanism were examined. Eight plant flavonoids were screened to evaluate their effects on B. tabaci adult sensitivity to thiamethoxam and flupyradifurone. Of which rutin, quercetin, kaempferol, myricetin and catechin significantly reduced adult sensitivity to thiamethoxam and flupyradifurone. Application of cytochrome P450 inhibitor piperonyl butoxide significantly increased the mortality of B. tabaci adults treated with thiamethoxam and flupyradifurone. Moreover, flavonoid ingestion predominantly enhanced the activity of cytochrome P450 enzyme in B. tabaci adults. Meanwhile, the expression level of three cytochrome P450 genes, CYP6CM1, CYP6CX4 and CYP4C64 were induced by the flavonoids in B. tabaci adults. In conclusion, plant flavonoids enhanced the tolerance to thiamethoxam and flupyradifurone in B. tabaci and cytochrome P450s may contribute the flavonoid adaptation. The reduced sensitivity of thiamethoxam and flupyradifurone in flavonoid-fed B. tabaci adults suggested that previous exposure to the host plant-derived flavonoids is likely to compromise the efficacy of insecticides.


Assuntos
Hemípteros , Inseticidas , 4-Butirolactona/análogos & derivados , Animais , Flavonoides/farmacologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Piridinas , Tiametoxam
19.
Molecules ; 26(22)2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34834020

RESUMO

Ochratoxin A (OTA) is a highly toxic mycotoxin and poses great threat to human health. Due to its serious toxicity and widespread contamination, great efforts have been made to evaluate its human exposure. This review focuses on the OTA occurrence and contamination level in nine plant and animal derived food commodities: cereal, wine, coffee, beer, cocoa, dried fruit, spice, meat, and milk. The occurrence and contamination level varied greatly in food commodities and were affected by many factors, including spices, geography, climate, and storage conditions. Therefore, risk monitoring must be routinely implemented to ensure minimal OTA intake and food safety.


Assuntos
Análise de Alimentos , Contaminação de Alimentos/análise , Alimentos , Ocratoxinas/análise , Animais , Humanos , Ocratoxinas/toxicidade
20.
J Sci Food Agric ; 101(5): 1767-1771, 2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32888337

RESUMO

BACKGROUND: Patulin is a mycotoxin that mainly contaminates apple juice, which is a typical high sugar matrix. Many different adsorbents have been utilized to develop a sample pretreatment method to minimize the matrix interference from apple juice. RESULTS: A simple and reliable extraction method for the determination of patulin in apple juice has been developed. The sample preparation involves a simple one-step cleanup procedure using amine-functionalized polymeric solid-phase extraction cartridges (Retain AX) that effectively remove interferences and facilitate the quantification. Isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) was employed to minimize the matrix effect and ensure reliable results. The limit of detection was as low as 0.2 µg kg-1 , which was satisfactory with regard to current European, US, and Chinese legislation. Matrix-matched linearity (r2 = 0.9997) was established in the range of 1-400 µg kg-1 . Recovery was performed in samples spiked at three levels, and results were between 97.2% and 100.2%. CONCLUSION: The results indicated that, with one-step cleanup, the matrix effect was negligible and sensitivity was satisfactory. Our work provided a simple and reliable method for patulin detection in apple juice and is also very promising in routine quality control. © 2020 Society of Chemical Industry.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sucos de Frutas e Vegetais/análise , Malus/química , Patulina/análise , Patulina/isolamento & purificação , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Aminas/química , Contaminação de Alimentos/análise , Frutas/química , Extração em Fase Sólida/instrumentação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA