RESUMEN
This study evaluated the residue behavior and dissipation dynamics of a new imidacloprid FS 600 seed treatment in potato cultivation systems in Shandong and Jilin, China. Sensitive and accurate UPLC-MS/MS methods were established to quantify imidacloprid residues in potatoes, potato plants, and soil. Results showed that imidacloprid dissipation followed a first-order kinetic model, with half-lives ranging from 6.9 to 26.7 days in plants and 19.8 to 28.9 days in soil. At harvest, the highest average residues in potatoes and soil were 0.778 mg/kg and 0.149 mg/kg, respectively. The dietary risk assessment indicated a chronic risk quotient (CRQ) of 39.73% for adults, indicating minimal risk to human consumers, while the ecological risk quotient (ERQ) and ecotoxicity exposure ratio (TER) revealed low to moderate toxicity to earthworms, warranting caution in the use of this formulation. This research provides valuable data for assessing the safety of imidacloprid FS seed treatment in potato cultivation.
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Neonicotinoides , Nitrocompuestos , Semillas , Solanum tuberosum , Solanum tuberosum/crecimiento & desarrollo , Solanum tuberosum/química , Solanum tuberosum/efectos de los fármacos , Neonicotinoides/análisis , China , Semillas/química , Residuos de Plaguicidas/análisis , Espectrometría de Masas en Tándem , Insecticidas , Suelo/química , Medición de Riesgo , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidadRESUMEN
Chloroamide herbicides can cause adverse effects on nontarget organisms, but there is limited information about their occurrence in the environment of major cropland growing regions. In this study, a total of 1012 soil samples, 617 surface water samples and 737 groundwater samples were collected from 2020 to 2021 in three regions of China to evaluate the occurrence and risk of three important chloroamide herbicides alachlor, acetochlor and butachlor using the improved QuEChERS extraction method and high performance liquid chromatography-mass spectrometry. The results showed that residues of the three chloroamide compounds in surface water and groundwater ranged from 0.1 to 176.0 µg L-1, of which acetochlor was frequently detected from surface water (17.5%). As for the soil, mass fraction was varied between 1.0 and 1540.3 µg kg-1, similarly acetochlor had the highest detection frequency (49.6%). Timewise, the median mass fraction of selected chloroamide herbicides in soil in 2021 (7.8 µg kg-1) was significantly lower than that in 2020 (10.9 µg kg-1). Spatially, there were regional differences in the content of environmental residues, and the overall level of residues in the northeast was relatively high. The environmental risk assessment based on the improved Risk Quotient (RQ) method indicated that the selected herbicides were currently within an acceptable range for human health risks in the soil and water environment in various regions, but acetochlor and butachlor had contributed to the RQ values of fish and earthworms (0.01ï¼RQï¼0.1) in recent years, respectively, which might pose a certain risk of oral exposure to aquatic and terrestrial organisms. This study provides valuable data and ideas for the rational application, pollution control and environmental safety evaluation of chloroamide herbicides in China.
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Herbicidas , Animales , Humanos , Herbicidas/análisis , Suelo , Agua , Medición de RiesgoRESUMEN
N-doped biochar is widely used for activating persulfate to degrade organic pollutants. Which type of N atom is the key factor for activation is still unclear and needs to be further explored and analyzed. In this study, four kinds of biochar were prepared using urea and rice husk as precursors, and tested for the catalytic degradation of dimethomorph. Increasing the nitrogen doping level caused the catalytic removal efficiency of dimethomorph in the presence of peroxymonosulfate increased from 16.6% to 86.8%. A correlation analysis showed that the ability of N-doped biochar to activate PMS is mainly related to the content of pyrrole N, graphite N and carbonyl and the degree of defects. In experiments on electron paramagnetic resonance and free radical suppression, the reactive species of SO4â¢-, 1O2,·OH and O2.- were detected, among which 1O2 was found to be the main agent in the nonradical pathway. The degradation pathways for dimethomorph were analyzed based on a total of 8 degradation products identified by high-performance liquid chromatography-time of flight mass spectrometry (HPLC-Q-TOFMS). The results of this study provide a fundamental basis for using agricultural waste to produce inexpensive and efficient nonmetal catalysts that are highly effective in reducing dimethomorph levels in agricultural lands.
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Oryza , Nitrógeno/química , Carbón Orgánico , Peróxidos/químicaRESUMEN
Polyunsaturated fatty acid (PUFA) synthase is a special and effective enzyme for PUFA synthesis, and dehydratase (DH) domain played a crucial role in it. In this work, we compared four different DH domains from different strains (Schizochytrium sp. HX-308 and Shewanella sp. BR-2) and different gene clusters. First bioinformatics analysis showed that DH1, 2 and DH3 were similar to FabA and PKS-DH, respectively, and all of them got a hot-dog structure. Second, four DH domains were expressed in Escherichia coli that increased biomass. Especially, Schi-DH1,2 presented the highest dry cell weight of 2.3 g/L which was 1.62 times of that of control. Fatty acids profile analysis showed that DH1,2 could enhance the percentage of unsaturated fatty acids, especially DH1,2 from Schizochytrium sp., while DH3 benefited for the saturated fatty acid biosynthesis. Furthermore, five kinds of fatty acids were added to the medium to study the substrate preferences. Results revealed that DH1,2 domain preferred to acting on C16:0, while DH3 domain trended acting on C14:0 and C15:0, which illustrated DH from different clusters do have specific substrate preference. Besides, DH expression could save the cell growth inhibition by mid-chain fatty acids. This study provided more information about the catalysis mechanism of polyunsaturated fatty acid synthase and might promote the modification study based on this enzyme.
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Ácidos Grasos/biosíntesis , Hidroliasas/metabolismo , Shewanella/química , Estramenopilos/químicaRESUMEN
BACKGROUND: Neurogenic bowel dysfunction (NBD) is a prevalent complication among stroke patients, significantly affecting their quality of life, duration of hospitalization, medical expenses, and even mortality. Although current guidelines suggest a conservative strategy for addressing bowel dysfunction, which includes techniques such as digital rectal stimulation (DRS) and abdominal massage, the availability of interventions remains limited in healthcare facilities. METHODS: This study follows a prospective randomized controlled parallel-group clinical trial design. The control group will receive standard care, while the intervention group will undergo a program that combines DRS and abdominal massage in addition to standard care. The duration of the intervention for both groups will be 6 weeks. The primary outcome measures will be the Wexner score. Furthermore, secondary outcomes measure will be assessed, including Bristol score, Patient Assessment of Constipation-Quality of Life (PAC-QoL), and Fecal Incontinence Quality of Life (FI-QoL). DISCUSSION: This study aims to evaluate the effectiveness and safety of a bowel rehabilitation program for stroke patients with NBD. The findings will provide information that can contribute to the formulation of bowel management strategies. TRIAL REGISTRATION: The study has been registered in the Chinese Clinical Registry under the number ChiCTR2300071709. This registration was completed on May 23, 2023. All items from the World Health Organization Trial Registration Data set are described in this manuscript.
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Intestino Neurogénico , Accidente Cerebrovascular , Humanos , Intestino Neurogénico/diagnóstico , Intestino Neurogénico/etiología , Intestino Neurogénico/terapia , Calidad de Vida , Estudios Prospectivos , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/terapia , Masaje/métodos , Resultado del Tratamiento , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
The risks posed by chemicals in the environment are typically assessed on a substance-by-substance basis, often neglecting the effects of mixtures. This may lead to an underestimation of the actual risk. In our study, we investigated the effects of three commonly used pesticides-imidacloprid (IMI), cycloxaprid (CYC), and tebuconazole (TBZ)-both individually and in combination, using various biomarkers to assess their impact on daphnia. Our findings indicated that the order of toxicity, from highest to lowest, was TBZ, IMI, and CYC, as determined by acute toxicity as well as reproduction. The effects of the ITmix (IMI and TBZ) and CTmix (CYC and TBZ) combinations on immobilization and reproduction were evaluated by MIXTOX, revealing a higher risk of immobilization at low concentrations for ITmix. The effect on reproduction differed depending on the ration of pesticides in the mixture, with synergism observed, which may be caused mainly by IMI. However, CTmix showed antagonism for acute toxicity, with the effect on reproduction depending upon the composition of the mixture. The response surface also exhibited a switch between antagonism and synergism. Additionally, the pesticides extended the body length and inhibited the development period. The activities of superoxide dismutase (SOD) and catalase (CAT) content was also significantly induced at different dosage points in both the single and combination groups, indicating changes in the metabolic capabilities of detoxifying enzymes and target site sensitivity. These findings highlight the need for more attention to be focused on the effects of pesticide mixtures.
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In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT50 of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe3+and NO3-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.
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Luz Solar , Contaminantes Químicos del Agua , Estrobilurinas , Espectrometría de Masas , Contaminantes Químicos del Agua/química , FotólisisRESUMEN
Carotenoids, an important kind of natural pigments with great potential commercial value, have been widely used in nutrition and health care, cosmetics and aquaculture industries. Schizochytrium sp. is a potential cell factory for lipid nutrition chemicals production including docosahexaenoic acid and carotenoids. The purpose of this study is to mine and identify the carotenoid biosynthesis genes in Schizochytrium sp. Firstly, based on the genomic information of Schizochytrium sp., we obtained the gene sequences of a trifunctional enzyme (CrtIBY), carotene hydroxylase (CrtZ) and carotene ketolase (CrtO) in carotenoids biosynthesis pathway by bioinformatics analysis. Subsequently, using the lycopene-producing E. coli as the host, 22.77 ug/L of ß-carotene and 44.31 ug/L of zeaxanthin were synthesized by overexpression of CrtIBY and further co-expression with CrtZ from Schizochytrium sp. After that, 54.78 ug/L of astaxanthin was synthesized using hydroxylase and ketonase from Haematococcus pluvialis. The key enzymes for carotenoids biosynthesis identified in this study is of great significance for further understanding the metabolic mechanism in Schizochytrium sp, which could also provide the functional elements and theoretical support for astaxanthin production.
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Escherichia coli , Oxigenasas , Carotenoides/metabolismo , Escherichia coli/genética , Oxigenasas/genética , Oxigenasas/metabolismo , Xantófilas/metabolismoRESUMEN
This study investigated the degradation of strobilurin fungicide kresoxim-methyl (KM) in three typical agricultural soils from China by aerobic and anaerobic degradation experiments, focusing on degradation kinetics of KM, identification of transformation products (TPs), and prediction of toxicity end points via in silico approaches. KM showed a pronounced biphasic degradation in different soils and could rapidly degrade, with DT50 of <3 days. Four TPs were identified by high-resolution mass spectrometry (HRMS), and three of them have never been reported before. Possible degradation pathways of KM in soil were proposed, including hydrolysis, oxidation, and reduction, and the main mechanism involved in the biodegradation of KM was the hydrolysis of methyl ester regardless of aerobic or anaerobic conditions. The results of toxicity evaluation indicated that some TPs are more toxic than KM and may have a developmental toxicity and mutagenicity, and further risk assessment should be carried out.
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Fungicidas Industriales , Contaminantes Químicos del Agua , Estrobilurinas , Suelo/química , Espectrometría de Masas , Fungicidas Industriales/metabolismo , Cinética , Contaminantes Químicos del Agua/análisisRESUMEN
Difenoconazole is a widely used triazole fungicide that has been frequently detected in the environment, but comprehensive study about its environmental fate and toxicity of potential transformation products (TPs) is still lacking. Here, laboratory experiments were conducted to investigate the degradation kinetics, pathways, and toxicity of transformation products of difenoconazole. 12, 4 and 4 TPs generated by photolysis, hydrolysis and soil degradation were identified via UHPLC-QTOF/MS and the UNIFI software. Four intermediates TP295, TP295A, TP354A and TP387A reported for the first time were confirmed by purchase or synthesis of their standards, and they were further quantified using UHPLC-MS/MS in all tested samples. The main transformation reactions observed for difenoconazole were oxidation, dechlorination and hydroxylation in the environment. ECOSAR prediction and laboratory tests showed that the acute toxicities of four novel TPs on Brachydanio rerio, Daphnia magna and Selenastrum capricornutum are substantially lower than that of difenoconazole, while all the TPs except for TP277C were predicted chronically very toxic to fish, which may pose a potential threat to aquatic ecosystems. The results are important for elucidating the environmental fate of difenoconazole and assessing the environmental risks, and further provide guidance for scientific and reasonable use.