The Experts below are selected from a list of 1473 Experts worldwide ranked by ideXlab platform
Randall Luttrell - One of the best experts on this subject based on the ideXlab platform.
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Biological response and enzymatic activities in Acephate-treated tarnished plant bug.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:*Natural field population collected in Lula, Mississippi.**Field population collected in Lula, Mississippi and treated with 600 mg/L of Acephate (90WP) before it was used for assays.
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Correlation of survival rates between Acephate-treated (OrRate) and imidacloprid-treated (ImRate) L. lineolaris collected in September, 2011 in northwest Mississippi.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:Correlation of survival rates between Acephate-treated (OrRate) and imidacloprid-treated (ImRate) L. lineolaris collected in September, 2011 in northwest Mississippi.
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Comparison and verification of transcriptional levels of two up-regulated (detected by microarray) esterase genes (LLE1 and LLE4) using absolute estimating method in real-time PCR.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:LLS: laboratory susceptible strain; Lula CK: field population collected from Lula MS as an aging control; Lula1000: field population collected from Lula MS and selected with 1,000 mg/L Acephate (90WP).
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variation of Acephate susceptibility and correlation with esterase and glutathione s transferase activities in field populations of the tarnished plant bug lygus lineolaris
Pesticide Biochemistry and Physiology, 2012Co-Authors: Yu Cheng Zhu, Randall LuttrellAbstract:Abstract The tarnished plant bug (TPB) has increasingly become an economically important pest of cotton. Heavy dependence on insecticides, particularly organophosphates and pyrethroids, for TPB control facilitated resistance development to multiple classes of insecticides. To better understand resistance and explore ways to monitor resistance in field populations, this study examined Acephate susceptibility and the activities of two major detoxification enzymes in nine field populations collected in the Delta region of Mississippi and Arkansas in 2010. Two Arkansas populations from Reed and Backgate had 3.5- and 4.3-fold resistance to Acephate, as compared to a susceptible laboratory strain. Extensive planting of cotton and heavy chemical sprays is a major driving force for resistance development to Acephate in Mid-south cotton growing areas. Reduced susceptibility to Acephate was highly correlated with elevated esterase activities. The Acephate-resistant populations from Backgate, Lula, and Reed consistently had higher (up to 5.3-fold) esterase activities than susceptible populations. Regression analysis of LC 50 s with kinetic esterase activities revealed a significant polynomial quadratic relationship with R 2 up to 0.89. Glutathione S -transferase (GST) also had elevated activity in most populations, but the variations of GST activities were not significantly correlated with changes of Acephate susceptibility. Finally, examination of esterase and GST inhibitors indicated that suppression rates (up to 70%) by two esterase inhibitors in 2010 were slightly lower than those detected in 2006, and ethacrynic acid (EA) inhibited GST effectively in both years. Two other GST inhibitors (sulfobromophthalein and diethyl maleate) displayed significantly lower suppression rates in 2010 than those detected in 2006, suggesting a potential genetic shift in pest populations and a necessity of continued monitoring for insecticide resistance with both bioassay and biochemical approaches. Results indicated that using major detoxification enzyme activities for resistance monitoring may provide insight into Acephate resistance in field populations of TPB.
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microarray analysis of gene regulations and potential association with Acephate resistance and fitness cost in lygus lineolaris
PLOS ONE, 2012Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:The tarnished plant bug has become increasingly resistant to organophosphates in recent years. To better understand Acephate resistance mechanisms, biological, biochemical, and molecular experiments were systematically conducted with susceptible (LLS) and Acephate-selected (LLR) strains. Selection of a field population with Acephate significantly increased resistance ratio to 5.9-fold, coupled with a significant increase of esterase activities by 2-fold. Microarray analysis of 6,688 genes revealed 329 up- and 333 down-regulated (≥2-fold) genes in LLR. Six esterase, three P450, and one glutathione S-transferase genes were significantly up-regulated, and no such genes were down-regulated in LLR. All vitellogenin and eggshell protein genes were significantly down-regulated in LLR. Thirteen protease genes were significantly down-regulated and only 3 were up-regulated in LLR. More than twice the number of catalysis genes and more than 3.6-fold of metabolic genes were up-regulated, respectively, as compared to those down-regulated with the same molecular and biological functions. The large portion of metabolic or catalysis genes with significant up-regulations indicated a substantial increase of metabolic detoxification in LLR. Significant increase of Acephate resistance, increases of esterase activities and gene expressions, and variable esterase sequences between LLS and LLR consistently demonstrated a major esterase-mediated resistance in LLR, which was functionally provable by abolishing the resistance with esterase inhibitors. In addition, significant elevation of P450 gene expression and reduced susceptibility to imidacloprid in LLR indicated a concurrent resistance risk that may impact other classes of insecticides. This study demonstrated the first association of down-regulation of reproductive- and digestive-related genes with resistance to conventional insecticides, suggesting potential fitness costs associated with resistance development. This study shed new light on the understanding of the molecular basis of insecticide resistance, and the information is highly valuable for development of chemical control guidelines and tactics to minimize resistance and cross-resistance risks.
Xinquan Wang - One of the best experts on this subject based on the ideXlab platform.
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environmental behavior of the chiral organophosphorus insecticide Acephate and its chiral metabolite methamidophos enantioselective transformation and degradation in soils
Environmental Science & Technology, 2013Co-Authors: Xiangyun Wang, Zhen Li, Hu Zhang, Junfeng Xu, Peipei Qi, Hao Xu, Qiang Wang, Xinquan WangAbstract:Acephate is a widely used organophosphorus insecticide globally, although there are some concerns about its usage with regard to acute consumer exposure and side-effects on nontarget organisms. These concerns are always attributed to the Acephate metabolite methamidophos. In the many reports about the environmental behavior of Acephate and its metabolite, none pay any attention to the chirality of them. In this study, the enantiomeric transformation and degradation of Acephate was investigated in three soils under laboratory conditions using enantioselective GC-MS/MS. Racemic and enantiopure compounds were incubated in separate experiments. The degradation of racemates was shown to be enantioselective in unsterilized soils but not in the sterilized soils, thus confirming the enantioselectivity was microbially based. The priority of enantiomer degradation and transformation varied among soils and racemates. R-(+)-methamidophos was enriched in the Zhengzhou soil, but degraded faster in the Changchun and Nan...
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direct chiral determination of Acephate and its metabolite methamidophos in vegetables using quechers by gas chromatography tandem mass spectrometry
Food Analytical Methods, 2013Co-Authors: Xiangyun Wang, Hu Zhang, Peipei Qi, Hao Xu, Qiang Wang, Xiaofeng Ji, Xinquan WangAbstract:Currently, methamidophos, the main metabolite of Acephate in the plants, has been paid particular attention in the risk evaluation of Acephate because of its severely accurate toxicity, but the chirality of methamidophos and Acephate has not been taken into account. In this study, a chiral separation and analysis method was developed to help evaluate the risks posing to the environment and human health. The efficiency of four commercial chiral capillary columns to accomplish enantioseparation of these two pesticides was firstly evaluated, and the chromatographic condition on the chose column BGB-176 SE was optimized. An analytical method for determination and confirmation of the enantiomers in vegetables by gas chromatography–tandem mass spectrometry was then developed with the column. QuEChERS was adopted to extract and clean the residues in vegetables. The mean recovery rates of quintuplicate results in cabbage and pakchoi ranged from 71.87 to 81.45 %; the relative standard deviation was less than 8.81 %. The limits of detection of enantiomers of Acephate and methamidophos were 0.008 and 0.005 mg/kg, respectively. After the application of the method to vegetables from a market, it was proved that the metabolism of Acephate and methamidophos in plants should be enantioselective.
Changhao Sun - One of the best experts on this subject based on the ideXlab platform.
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metabolomic analysis of the toxic effect of chronic low dose exposure to Acephate on rats using ultra performance liquid chromatography mass spectrometry
Ecotoxicology and Environmental Safety, 2012Co-Authors: Dongfang Hao, Hong Wang, Jindan Yang, Xiujuan Zhao, Changhao SunAbstract:To study the toxic effect of chronic exposure to Acephate at low-dose levels, a metabolomics approach based on ultra-performance liquid chromatography/mass spectrometry (UPLC-MS) was applied. Three different doses of 0.5 mg/kg/day, 1.5 mg/kg/day, and 4.5 mg/kg/day Acephate were administered to Wistar rats for 24 weeks. Endogenous metabolite profiles were obtained with UPLC-MS for all rats at six time points after treatment. Some metabolites like dimethylthiophosphate and uric acid in urine were detected at week 4. Dimethylthiophosphate, which had the most significant elevations compared with other biomarkers, was considered as an early, sensitive biomarker of exposure to Acephate. Moreover, there were some endogenous metabolite changes, which demonstrated that the doses of 1.5 mg/kg/day and 4.5 mg/kg/day of Acephate led to renal injury and perturbed the normal metabolic processes of rats, including glucose, nucleic acid, and protein metabolism. A connection between exposure to Acephate and the metabolic disturbance has been found and interpreted. Our study indicates that the metabolomics approach based on UPLC-MS of urine provides more information on toxicity than the conventional toxicological evaluation methods in measuring changes and can be considered as a promising technique for the study of the toxic effect of Acephate.
Yu Cheng Zhu - One of the best experts on this subject based on the ideXlab platform.
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Microarray Analysis of Gene Regulations and Potential Association with Acephate-Resistance and Fitness Cost in
2016Co-Authors: Lygus Lineolaris, Yu Cheng Zhu, Zibiao Guo, All LuttrellAbstract:The tarnished plant bug has become increasingly resistant to organophosphates in recent years. To better understand Acephate resistance mechanisms, biological, biochemical, and molecular experiments were systematically conducted with susceptible (LLS) and Acephate-selected (LLR) strains. Selection of a field population with Acephate significantly increased resistance ratio to 5.9-fold, coupled with a significant increase of esterase activities by 2-fold. Microarray analysis of 6,688 genes revealed 329 up- and 333 down-regulated ($2-fold) genes in LLR. Six esterase, three P450, and one glutathione S-transferase genes were significantly up-regulated, and no such genes were down-regulated in LLR. All vitellogenin and eggshell protein genes were significantly down-regulated in LLR. Thirteen protease genes were significantly down-regulated and only 3 were up-regulated in LLR. More than twice the number of catalysis genes and more than 3.6-fold of metabolic genes were up-regulated, respectively, as compared to those down-regulated with the same molecular and biological functions. The large portion of metabolic or catalysis genes with significant up-regulations indicated a substantial increase of metabolic detoxification in LLR. Significant increase of Acephate resistance, increases of esterase activities and gene expressions, and variable esterase sequences between LLS and LLR consistently demonstrated a major esterase-mediated resistance in LLR, which was functionally provable by abolishing the resistance with esterase inhibitors. In addition, significant elevation of P450 gene expression and reduced susceptibility to imidacloprid in LLR indicated
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Correlation of survival rates between Acephate-treated (OrRate) and imidacloprid-treated (ImRate) L. lineolaris collected in September, 2011 in northwest Mississippi.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:Correlation of survival rates between Acephate-treated (OrRate) and imidacloprid-treated (ImRate) L. lineolaris collected in September, 2011 in northwest Mississippi.
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Biological response and enzymatic activities in Acephate-treated tarnished plant bug.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:*Natural field population collected in Lula, Mississippi.**Field population collected in Lula, Mississippi and treated with 600 mg/L of Acephate (90WP) before it was used for assays.
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Comparison and verification of transcriptional levels of two up-regulated (detected by microarray) esterase genes (LLE1 and LLE4) using absolute estimating method in real-time PCR.
2013Co-Authors: Yu Cheng Zhu, Zibiao Guo, Randall LuttrellAbstract:LLS: laboratory susceptible strain; Lula CK: field population collected from Lula MS as an aging control; Lula1000: field population collected from Lula MS and selected with 1,000 mg/L Acephate (90WP).
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variation of Acephate susceptibility and correlation with esterase and glutathione s transferase activities in field populations of the tarnished plant bug lygus lineolaris
Pesticide Biochemistry and Physiology, 2012Co-Authors: Yu Cheng Zhu, Randall LuttrellAbstract:Abstract The tarnished plant bug (TPB) has increasingly become an economically important pest of cotton. Heavy dependence on insecticides, particularly organophosphates and pyrethroids, for TPB control facilitated resistance development to multiple classes of insecticides. To better understand resistance and explore ways to monitor resistance in field populations, this study examined Acephate susceptibility and the activities of two major detoxification enzymes in nine field populations collected in the Delta region of Mississippi and Arkansas in 2010. Two Arkansas populations from Reed and Backgate had 3.5- and 4.3-fold resistance to Acephate, as compared to a susceptible laboratory strain. Extensive planting of cotton and heavy chemical sprays is a major driving force for resistance development to Acephate in Mid-south cotton growing areas. Reduced susceptibility to Acephate was highly correlated with elevated esterase activities. The Acephate-resistant populations from Backgate, Lula, and Reed consistently had higher (up to 5.3-fold) esterase activities than susceptible populations. Regression analysis of LC 50 s with kinetic esterase activities revealed a significant polynomial quadratic relationship with R 2 up to 0.89. Glutathione S -transferase (GST) also had elevated activity in most populations, but the variations of GST activities were not significantly correlated with changes of Acephate susceptibility. Finally, examination of esterase and GST inhibitors indicated that suppression rates (up to 70%) by two esterase inhibitors in 2010 were slightly lower than those detected in 2006, and ethacrynic acid (EA) inhibited GST effectively in both years. Two other GST inhibitors (sulfobromophthalein and diethyl maleate) displayed significantly lower suppression rates in 2010 than those detected in 2006, suggesting a potential genetic shift in pest populations and a necessity of continued monitoring for insecticide resistance with both bioassay and biochemical approaches. Results indicated that using major detoxification enzyme activities for resistance monitoring may provide insight into Acephate resistance in field populations of TPB.
Hiroshi Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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chimeric mice with humanized liver as a model for testing organophosphate and carbamate pesticide exposure
Pest Management Science, 2018Co-Authors: Hiroshi Suemizu, Kenji Kawai, Norie Murayama, Masato Nakamura, Hiroshi YamazakiAbstract:BACKGROUND Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes. RESULTS A single oral administration of Acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose-dependent decreases in plasma BuChE activity were also observed for Acephate and chlorpyrifos. A 5-day repeated-dose study with 10 or 30 mg/kg Acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre-dose levels, respectively. CONCLUSION Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized-liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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pharmacokinetics and effects on serum cholinesterase activities of organophosphorus pesticides Acephate and chlorpyrifos in chimeric mice transplanted with human hepatocytes
Regulatory Toxicology and Pharmacology, 2014Co-Authors: Hiroshi Suemizu, Shigeto Sota, Miyuki Kuronuma, Makiko Shimizu, Hiroshi YamazakiAbstract:Organophosphorus pesticides Acephate and chlorpyrifos in foods have potential to impact human health. The aim of the current study was to investigate the pharmacokinetics of Acephate and chlorpyrifos orally administered at lowest-observed-adverse-effect-level doses in chimeric mice transplanted with human hepatocytes. Absorbed Acephate and its metabolite methamidophos were detected in serum from wild type mice and chimeric mice orally administered 150 mg/kg. Approximately 70% inhibition of cholinesterase was evident in plasma of chimeric mice with humanized liver (which have higher serum cholinesterase activities than wild type mice) 1 day after oral administrations of Acephate. Adjusted animal biomonitoring equivalents from chimeric mice studies were scaled to human biomonitoring equivalents using known species allometric scaling factors and in vitro metabolic clearance data with a simple physiologically based pharmacokinetic (PBPK) model. Estimated plasma concentrations of Acephate and chlorpyrifos in humans were consistent with reported concentrations. Acephate cleared similarly in humans and chimeric mice but accidental/incidental overdose levels of chlorpyrifos cleared (dependent on liver metabolism) more slowly from plasma in humans than it did in mice. The data presented here illustrate how chimeric mice transplanted with human hepatocytes in combination with a simple PBPK model can assist evaluations of toxicological potential of organophosphorus pesticides.