Yan Wang

China Agricultural University, Peping, Beijing, China

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Publications (9)27.6 Total impact

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    ABSTRACT: Ochratoxin A (OTA) is one of the most toxic mycotoxins, which is toxic to plants and simulates oxidative stress. Glutathione is an important antioxidant in plants and is closely associated with detoxification in cells. We have previously shown that OTA exposure induces obvious expression differences in genes associated with glutathione metabolism. To characterize glutathione metabolism and understand its role in OTA phytotoxicity, we observed the accumulation of GSH in the detached leaves of Arabidopsis thaliana under OTA treatment. OTA stimulated a defense response through enhancing glutathione-S-transferase, glutathione peroxidase, glutathione reductase activities, and the transcript levels of these enzymes were increased to maintain the total glutathione content. Moreover, the level of oxidized glutathione (GSSG) was increased and the ascorbate-glutathione cycle fluctuated in response to OTA. The depletion of glutathione using buthionine sulfoximine (BSO, inhibitor of glutamate-cysteine ligase) had no profound effect on OTA toxicity, as glutathione was regenerated through the ascorbate-glutathione cycle to maintain the total glutathione content. The ROS, MDA and GSH accumulation was significantly affected in the mutant gsh1, gr1 and gpx2 after treatment with OTA, which indicated that glutathione metabolism is directly involved in the oxidative stress response of Arabidopsis thaliana subjected to OTA. In conclusion, date demonstrate that glutathione-associated metabolism is closely related with OTA stress and glutathione play a role in resistance of Arabidopsis subjected to OTA.
    Plant Physiology and Biochemistry 01/2014; · 2.78 Impact Factor
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    ABSTRACT: Ochratoxin A (OTA) is a ubiquitous mycotoxin with potential nephrotoxic, hepatotoxic and immunotoxic effects. The mechanisms underlying the nephrotoxicity of OTA remain obscure. To investigate DNA damage and the changes of the cell cycle distribution induced by OTA, human embryonic kidney cells (HEK 293 cells) were incubated with various concentrations of OTA for 24 h in vitro. The results indicated that OTA treatment led to the production of reactive oxygen species (ROS) and to a decrease of the mitochondrial membrane potential (ΔΨm). OTA-induced DNA damage in HEK 293 cells was evidenced by DNA comet tail formation and increased expression of γ-H2AX. In addition, OTA could induce cell cycle arrest at the S phase in HEK 293 cells. The expression of key cell cycle regulatory factors that were critical to the S phase, including cyclin A2, cyclin E1 and CDK2, were further detected. The expression of cyclin A2, cyclin E1 and CDK2 were significantly decreased by OTA treatment at both the mRNA and protein levels. The apoptosis of HEK 293 cells after OTA treatment was observed using Hoechst 33342 staining. The results confirmed that OTA did induce apoptosis in HEK 293 cells. In conclusion, our results provided new insights into the molecular mechanisms by which OTA might promote nephrotoxicity.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 01/2014;
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    ABSTRACT: Ochratoxin A (OTA) is a mycotoxin that is primarily produced by Aspergillus ochraceus and Penicillium verrucosum. This mycotoxin is a contaminant of food and feedstock worldwide and may induce cell death in plants. To investigate the dynamic growth process of Arabidopsis seedlings in response to OTA stress and to obtain a better understanding of the mechanism of OTA toxicity towards Arabidopsis, a comparative proteomics study using 2-DE and MALDI-TOF/TOF MS/MS was performed. Mass spectrometry analysis identified 59 and 51 differentially expressed proteins in seedlings exposed to 25 and 45 μM OTA for 7 days, respectively. OTA treatment decreased root elongation and leaf area, increased anthocyanin accumulation, damaged the photosynthetic apparatus and inhibited photosynthesis. Treatment of the seedlings with 25 μM OTA enhanced energy metabolism, whereas higher concentration of OTA (45 μM) inhibited energy metabolism in the seedlings. OTA treatment caused an increase of ROS, an enhancement of antioxidant enzyme defense responses, disturbance of redox homeostasis and activation of lipid oxidation. Glutamine and S-adenosylmethionine metabolism may also play important roles in the response to OTA. In conclusion, our study provided novel insights regarding the response of Arabidopsis to OTA at the level of the proteome. These results are expected to be highly useful for understanding the physiological responses and dissecting the OTA response pathways in higher plants.
    Plant Molecular Biology 04/2013; · 3.52 Impact Factor
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    ABSTRACT: Nephrotoxicity is the most prominent of ochratoxin A (OTA) among the diverse range of toxicological effects. Previous work indicated that reactive oxygen species (ROS) play an important role in the pathogenesis of a variety of renal diseases, and its major endogenous source is mitochondria. No research has used global protein expression profiling to investigate potential toxicity mechanisms of OTA at the mitochondria level. An iTRAQ-based mitoproteomics approach was used to explore possible toxicity mechanisms of OTA and potential protective mechanisms of N-acetyl-L-cysteine (NAC) using the mitochondria of Human Embryonic Kidney 293 (HEK 293) cells. Our results showed that OTA induced a decrease in ΔΨm, and an increase in ROS and cell death. We identified a total of 1973 nonredundant proteins, among which 1398 proteins (70.86%) were overlapped. There were 66 significantly different proteins expressed in response to OTA, which were mainly involved in the perturbation of the mitochondrial electron transport chain (mETC), inhibition of protein synthesis, and induction of stress response and cell death. In addition, NAC could almost completely reverse the adverse effects of OTA at the protein level. Finally, a hypothetical model of OTA-induced mitochondria damage is proposed to provide a framework for the toxicity mechanism of OTA.
    Journal of proteomics 10/2012; · 5.07 Impact Factor
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    ABSTRACT: BACKGROUND: Fumonisins are a group of naturally occurring mycotoxins produced by various Fusarium species that commonly infect maize and other cereals, including sorghum and rice. In this study a sensitive and selective method was developed for the determination of fumonisins B(1) and B(2) (FB(1) and FB(2) ) in Chinese rice wine. The method is based on high-performance liquid chromatography and fluorescence detection following precolumn derivatisation with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). RESULTS: FB(1) and FB(2) in Chinese rice wine were extracted and purified using strong anion exchange cartridges and derivatised with AQC at room temperature. The AQC derivatives were stable for 5 days. Optimal fluorescence was obtained at an excitation wavelength of 246 nm and an emission wavelength of 390 nm. Chromatography was performed using a C(18) column and gradient elution at 1 mL min(-1) with methanol and 0.05 mol L(-1) phosphate buffer at pH 4. The limit of detection was 6 µg L(-1) for both FB(1) and FB(2) . The method was successfully applied to the determination of FB(1) and FB(2) in Chinese rice wine, with recoveries of 87.5-94.5% being obtained. CONCLUSION: The established method was stable and sensitive for the determination of FB(1) and FB(2) in Chinese rice wine. Copyright © 2012 Society of Chemical Industry.
    Journal of the Science of Food and Agriculture 08/2012; · 1.88 Impact Factor
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    ABSTRACT: Nutritional assessment of transgenic crops used for human food and animal feed is an important component of safety evaluations. Profiling techniques, such as proteomics, are currently used as complementary analytical tools to detect the unintended effects of transgenic. We analyzed the proteomic profiles and nutritional composition of transgenic rice seeds containing the Cry1Ab/Ac protein to assess the safety of these transgenic seeds. We focused primarily on the effects of genetic modification and growth environment. By comparing proteomic profiles, we found that 21 proteins were up- or down-regulated as a consequence of environmental influence (WT01 vs. WT02). Similarly, 20 to 22 protein levels were differentially modulated in transgenic rice seeds in comparison to their non-transgenic counterparts (T01 vs. WT01; T02 vs. WT02). These latter changes may be due to the influence of growth environment and the insertion of a single gene into the rice genome. Based on the nutrient composition analysis (proximates, amino acids, fatty acids, minerals, vitamins and anti-nutritive components), we conclude that the nutritional quality of the rice from the transgenic lines was equivalent to that of its non-transgenic counterparts and that the effect of growth environment on the rice was no less than that of the single gene insertion.
    Journal of Cereal Science 03/2012; 55(2):226–233. · 2.09 Impact Factor
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    ABSTRACT: Grapefruit seed extract (GSE), which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL) and 4,6'-diaminidino-2-phenylindole (DAPI) staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential) and ROS (reactive oxygen species) indicated that the mitochondria took part in the apoptotic process. Changes in this process detected by metabonomics and proteomics revealed that the yeast cells tenaciously resisted adversity. Proteins related to redox, cellular structure, membrane, energy and DNA repair were significantly increased. In this study, the relative changes in the levels of proteins and metabolites showed the tenacious resistance of yeast cells. However, GSE induced apoptosis in the yeast cells by destruction of the mitochondrial 60 S ribosomal protein, L14-A, and prevented the conversion of pantothenic acid to coenzyme A (CoA). The relationship between the proteins and metabolites was analyzed by orthogonal projections to latent structures (OPLS). We found that the changes of the metabolites and the protein changes had relevant consistency.
    PLoS ONE 01/2012; 7(3):e32943. · 3.53 Impact Factor
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    ABSTRACT: Ochratoxin A (OTA) is a toxic isocoumarin derivative produced by various species of mould which mainly grow on grain, coffee, and nuts. Recent studies have suggested that OTA induces cell death in plants. To investigate possible mechanisms of OTA phytotoxicity, both digital gene expression (DGE) transcriptomic and two-dimensional electrophoresis proteomic analyses were used, through which 3118 genes and 23 proteins were identified as being up- or down-regulated at least 2-fold in Arabidopsis leaf in response to OTA treatment. First, exposure of excised Arabidopsis thaliana leaves to OTA rapidly causes the hypersensitive reponse, significantly accelerates the increase of reactive oxygen species and malondialdehyde, and enhances antioxidant enzyme defence responses and xenobiotic detoxification. Secondly, OTA stimulation causes dynamic changes in transcription factors and activates the membrane transport system dramatically. Thirdly, a concomitant persistence of compromised photosynthesis and photorespiration is indicative of a metabolic shift from a highly active to a weak state. Finally, the data revealed that ethylene, salicylic acid, jasmonic acid, and mitogen-activated protein kinase signalling molecules mediate the process of toxicity caused by OTA. Profiling analyses on Arabidopsis in response to OTA will provide new insights into signalling transduction that modulates the OTA phytotoxicity mechanism, facilitate mapping of regulatory networks, and extend the ability to improve OTA tolerance in Arabidopsis.
    Journal of Experimental Botany 12/2011; 63(5):2171-87. · 5.79 Impact Factor
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    ABSTRACT: We evaluated the phytotoxicity of mycotoxin ochratoxin A (OTA) from Aspergillus and Penicillium strains on Arabidopsis thaliana. The results demonstrate that the growth of Arabidopsis thaliana on media containing OTA was inhibited significantly. Moreover, OTA induced necrotic lesions in detached leaves, which are reminiscent of hypersensitive response lesions that are activated during plant-pathogen interactions and other abiotic stress factors. From our study, we can see that OTA exposure stimulated a biphasic oxidative burst in the leaves, resulting in the generation of hydrogen peroxide (H2O2) and superoxide anion radicals (O2(.-)) and in the concomitant down-regulation of antioxidant enzyme defense responses and up-regulation of lipid peroxidation. These results suggested that OTA damage might result from reactive oxygen species pathways. Our experiments provide a useful model plant system for research on OTA-induced plant cell death.
    Plant Cell Reports 02/2010; 29(2):153-61. · 2.94 Impact Factor