Keiko Gion

Kobe University, Kōbe, Hyōgo, Japan

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Publications (9)17.61 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Tobacco cytochrome P450 (CYP) 71AH11 metabolized the herbicide chlorotoluron, and its mRNA level was increased in tobacco culture cells by the treatment of 2,4-D. In order to clarify molecular mechanisms of induced gene expression of CYP71AH11 by herbicide treatment, a 1574-bp 5′-flanking region of CYP71AH11 was cloned, ligated to the reporter β-glucuronidase (GUS) gene, and then transformed into tobacco plants. The GUS activity in the transgenic tobacco plants was highly induced by bromoxynil treatment, followed by 2,4-D. Chlorotoluron was slightly increased the GUS activity. The bromoxynil-increased GUS activity was partially repressed by the antioxidants, suggesting that reactive oxygen species may be involved in activation of the 5′-flanking region of CYP71AH11 by bromoxynil treatment. Deletion and mutation assays showed that the region CD (−1281 to −770 bp from the start codon of CYP71AH11) was important, but not sufficient, for response to bromoxynil. Electrophoretic mobility shift assays and southwestern blotting revealed that the sequences AAAAAG, and GAACAAAC and GAAAATTC in the CD region were important for interaction to the nuclear proteins of < 30 and ≈ 75 kDa, respectively. Particularly, interaction between AAAAAG and < 30 kDa proteins was increased by bromoxynil treatment. These results gave a cue for understanding the bromoxynil-induced gene expression of CYP71AH11, which may contribute to herbicide tolerance and selectivity in crop plants.
    Pesticide Biochemistry and Physiology 01/2014; · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tobacco cytochrome P450 (CYP) 71AH11 metabolized the herbicide chlorotoluron, and its mRNA level was increased in tobacco culture cells by the treatment of 2,4-D. In order to clarify molecular mechanisms of induced gene expression of CYP71AH11 by herbicide treatment, a 1574-bp 5'-flanking region of CYP71AH11 was cloned, ligated to the reporter β-glucuronidase (GUS) gene, and then transformed into tobacco plants. The GUS activity in the transgenic tobacco plants was highly induced by bromoxynil treatment, followed by 2,4-D. Chlorotoluron was slightly increased the GUS activity. The bromoxynil-increased GUS activity was partially repressed by the antioxidants, suggesting that reactive oxygen species may be involved in activation of the 5'-flanking region of CYP71AH11 by bromoxynil treatment. Deletion and mutation assays showed that the region CD (-1281 to -770bp from the start codon of CYP71AH11) was important, but not sufficient, for response to bromoxynil. Electrophoretic mobility shift assays and southwestern blotting revealed that the sequences AAAAAG, and GAACAAAC and GAAAATTC in the CD region were important for interaction to the nuclear proteins of <30 and ≈75kDa, respectively. Particularly, interaction between AAAAAG and <30kDa proteins was increased by bromoxynil treatment. These results gave a cue for understanding the bromoxynil-induced gene expression of CYP71AH11, which may contribute to herbicide tolerance and selectivity in crop plants.
    Pesticide Biochemistry and Physiology 01/2014; 108:49-57. · 2.11 Impact Factor
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    ABSTRACT: Certain congeners of polychlorinated biphenyls (PCBs) and organochlorine insecticides are ligands of aryl hydrocarbon receptors (AhRs) in animals. A recombinant guinea pig (g) AhR, XgDV, was constructed by fusing the ligand-binding domain of gAhR, the DNA-binding domain of LexA, and the transactivating domain of VP16. Then, the expression unit of β-glucuronidase (GUS) reporter gene regulated by XgDV was introduced into Arabidopsis and tobacco plants. When the transgenic Arabidopsis XgDV plants were cultured on Murashige-Skoog (MS) medium containing PCB congeners, the GUS activity in the plants increased toxic equivalent (TEQ)-dependently. The GUS activity in the transgenic Arabidopsis XgDV plants cultured on MS medium containing the organochlorine insecticide dieldrin was also induced. On the other hand, in the case of DDT, the GUS activity induced by 3-methylcholanthere in the plants decreased. The transgenic Arabidopsis XgDV plants detected 1000 ng g(-1) PCB126 in 1 g of soils. Thus the XgDV plants seemed to be useful for convenient assays of PCB congeners and organochlorine insecticides, without any extraction and purification steps.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 08/2012; 47(7):599-607. · 1.10 Impact Factor
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    ABSTRACT: The transgenic tobacco plant XD4V-26 carrying the recombinant mouse aryl hydrocarbon receptor XD4V-mediated β-glucuronidase (GUS) reporter gene expression system was used for assay of dioxins and dioxin-like compounds consisting of polychlorodibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls (Co-PCBs) in actually contaminated soils. The transgenic tobacco plant XD4V-26 showed a significant dose-dependent induced GUS activity when cultured on MS medium containing PCB126 [toxic equivalency factor (TEF) = 0.1]. In contrast, PCB169 and PCB180, which have 0.03 of TEF and unassigned TEF values, respectively, did not significantly induce GUS activity under the same conditions as with PCB126. When the tobacco plants were cultivated for up to 5 weeks on actually contaminated soils with dioxins and dioxin-like compounds collected from the periphery of an incinerator used for disposal of life and industrial wastes, GUS activity in the leaves was dose-dependently increased. The plants clearly detected 360 pg-TEQ g(-1) of dioxins and dioxin-like compounds in this assay. There was a positive correlation between GUS activity and TEQ value of dioxins and dioxin-like compounds in the plants. This assay does not require any extraction and purification processes for the actually contaminated soil samples.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 04/2012; 47(4):233-9. · 1.10 Impact Factor
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    ABSTRACT: The transgenic tobacco plant XD4V-26 carrying the recombinant mouse aryl hydrocarbon receptor XD4V-mediated β-glucuronidase (GUS) reporter gene expression system was used for assay of dioxins and dioxin-like compounds consisting of polychlorinated dibenzeno-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls (Co-PCBs) in actually contaminated soils. The transgenic tobacco plant XD4V-26 showed a significant dose-dependent induced GUS activity when cultured on MS medium containing PCB126 [toxic equivalency factor (TEF) = 0.1]. In contrast, PCB169 and PCB180, which have 0.03 of TEF and unassigned TEF values, respectively, did not significantly induce GUS activity under the same conditions as with PCB126. When the tobacco plants were cultivated for up to 5 weeks on actually contaminated soils with dioxins and dioxin-like compounds collected from the periphery of an incinerator used for disposal of residential and industrial wastes, GUS activity in the leaves was dose-dependently increased. The plants clearly detected 360 pg-TEQ g(-1) of dioxins and dioxin-like compounds in this assay. There was a positive correlation between GUS activity and TEQ value of dioxins and dioxin-like compounds in the plants. This assay does not require any extraction and purification processes for the actually contaminated soil samples.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 01/2012; 47(1):59-65. · 1.10 Impact Factor
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    ABSTRACT: Zucchini cultivars Cucurbita pepo subsp. ovifera cv. Patty Green and subsp. pepo cv. Gold Rush were cultivated hydroponically in a nutrient solution supplemented with a mixture of dioxins and dioxin-like compounds. Patty Green and Gold Rush showed low and high accumulation of these compounds in the aerial parts respectively. In both cultivars, the accumulation of each congener negatively depended on its hydrophobicity. This suggests that desorption and solubilization were partly responsible for congener specificity of accumulation, since this was not found in soil experiments. In contrast, no clear difference in accumulation in the roots was observed between the cultivars, whereas the translocation factors, which are indicators of efficient translocation from the roots to the aerial parts, differed among the congeners hydrophobicity-dependently. There were positive correlations between accumulation in the roots and the hydrophobicity of the polychlorinated biphenyl congeners in both cultivars. These results indicate that translocation was also partly responsible for the congener specificity and accumulation concentrations.
    Bioscience Biotechnology and Biochemistry 05/2011; 75(4):705-10. · 1.27 Impact Factor
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    ABSTRACT: Many recombinant transcription factors have been invented, but we cannot select a substance used as an inducer. In this study, we have created a novel expression control system in which we can select a substance as an inducer toward which a monoclonal antibody (mAb) is prepared. The variable region fragments (Fvs) of the heavy and light chains (V(H) and V(L)) of the bisphenol A (BPA)-specific mAb BBA-2187 were each fused to the DNA-binding domain (DBD) of LexA and the transactivation domain (AD) of VP16. The association between the two recombinant proteins in the presence of BPA constituted a functional transcription factor. The recombinant proteins in which the DBD was fused to the N-terminal side of the Fv and in which the nuclear localization signal (NLS) was fused to the N-termini of the construct including the AD highly induced beta-galactosidase (lacZ) expression in recombinant yeast cells grown with BPA. When the Fvs of the polychlorinated biphenyl (PCB)-specific mAb 4444 were used, DBD-NLS-V(H) and NLS-AD-V(L) showed significantly increased lacZ activity in response to a PCB derivative. The Fv transcription factor may be useful in many fields such as gene therapeutics.
    Analytical Chemistry 11/2009; 81(24):10162-6. · 5.70 Impact Factor
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    ABSTRACT: The zucchini (Cucurbita pepo) cultivars 'Patty Green', 'Black Beauty', and 'Gold Rush' were cultivated on weathered dioxin-contaminated soil in pots, and concentrations of the 29 dioxin-like compounds that were assigned WHO-TEFs, three non-toxic polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), and two non-dioxin-like polychlorinated biphenyls (PCBs) were analyzed. Toxic equivalent (TEQ) values accumulated in 'Black Beauty' and 'Gold Rush' were about 180 times higher than those in 'Patty Green'. The bioconcentration factor (BCF) based on total mass concentration of the twelve dioxin-like PCBs was higher than those of the seven PCDDs and ten PCDFs in all the cultivars. The BCFs for PCDD and PCDF congeners were negatively correlated with octanol-water partition coefficients in all the plants. No correlations were observed in PCB congeners in the high accumulators, although in 'Patty Green' the BCFs for PCB congeners were significantly correlated with octanol-water partition coefficients. Our findings suggest that the high accumulators had unknown, unique mechanisms for uptake of PCBs, whereas PCDDs and PCDFs were absorbed based on their physicochemical properties.
    Chemosphere 11/2008; 73(10):1602-7. · 3.14 Impact Factor
  • 05/2007: pages 431 - 438; , ISBN: 9783527611249