Assays of dioxins and dioxin-like compounds in actually contaminated soils using transgenic tobacco plants carrying a recombinant mouse aryl hydrocarbon receptor-mediated β-glucuronidase reporter gene expression system

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.

Zinc finger protein genes from Cucurbita pepo are promising tools for conferring non-Cucurbitaceae plants with ability to accumulate persistent organic pollutants

“…To explore the function of the CpZFPs, we used transgenic tobacco plants that carry AhR and GUS genes and can be used to evaluate the accumulation of dioxins and dioxin-like compounds in the plants by measurement of GUS activity (Inui et al, 2012). These plants, transformed with constructs to produce CpZFPs, can be expected to show enhanced accumulation of these compounds, resulting in high GUS activity.…”

“…GUS activity was measured by a previously reported method (Inui et al, 2012). All transgenic tobacco plants were incubated in Murashige and Skoog medium containing 0.1% dimethyl sulfoxide or 100 ng mL À1 CB126 for 2 weeks.…”

“…The genes related to high accumulation of the hydrophobic compounds were investigated by expression of the selected genes in transgenic tobacco plants. XD4V-26 tobacco plants, which express the genes for the mouse aryl hydrocarbon receptor (AhR) and the reporter b-glucuronidase (GUS), show increased GUS activity when treated with 3,3 0 ,4,4 0 ,5-pentachlorobiphenyl (CB126) or when cultivated in soil containing dioxins and dioxin-like compounds (Inui et al, 2012). Accumulation of these compounds in the aerial parts of the XD4V-26 plants can be revealed by measuring GUS activity in the leaves because GUS activity and the concentrations of dioxins and dioxin-like compounds in their aerial parts are significantly correlated (Inui et al, 2012).…”

“…XD4V-26 tobacco plants, which express the genes for the mouse aryl hydrocarbon receptor (AhR) and the reporter b-glucuronidase (GUS), show increased GUS activity when treated with 3,3 0 ,4,4 0 ,5-pentachlorobiphenyl (CB126) or when cultivated in soil containing dioxins and dioxin-like compounds (Inui et al, 2012). Accumulation of these compounds in the aerial parts of the XD4V-26 plants can be revealed by measuring GUS activity in the leaves because GUS activity and the concentrations of dioxins and dioxin-like compounds in their aerial parts are significantly correlated (Inui et al, 2012). These genes may be useful not only for clarification of the mechanisms of crop contamination but also for the production of plants that are suitable for phytoremediation of soil containing hydrophobic contaminants.…”

Assays of PCB congeners and organochlorine insecticides with the transgenicArabidopsisand tobacco plants carrying recombinant guinea pig AhR and GUS reporter genes

“…[10,11] In this study, a recombinant guinea pig (g) AhR, XgDV, was constructed by substituting the mD region in the XmDV with the ligand-binding domain of gAhR (gD), and then introduced into Arabidopsis and tobacco plants together with GUS reporter gene expression unit, since guinea pigs showed the highest sensitivity in toxicity to 2,3,7,8-TCDD among mammals tested and gAhR showed the highest affinity to 2,3,7,8-TCDD among mammalian AhRs. Transgenic Arabidopsis and tobacco plants carrying the XgDV and GUS expression unit were examined for assays of POPs acting as AhR ligands without any extraction and purification steps.…”