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Atrazine

The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Michael J. Lydy – 1st expert on this subject based on the ideXlab platform

  • impact of Atrazine on organophosphate insecticide toxicity
    Environmental Toxicology and Chemistry, 2000
    Co-Authors: J. B. Belden, Michael J. Lydy

    Abstract:

    Acute toxicity of selected organophosphorus insecticides (OPs; chlorpyrifos, methyl parathion, diazinon, and malathion) was determined for individual OPs and binary combinations of the OPs with Atrazine to larvae of the midge Chironomus tentans. Atrazine individually was not acutely toxic even at high concentrations (10,000 mg/L); however, the presence of Atrazine at much lower concentrations (40-200 mg/L) increased the toxicity of chlorpyrifos, methyl parathion, and diazinon. Atrazine did not increase the toxicity of malathion. Possible mechanisms for the synergistic toxicity found between Atrazine and chlorpyrifos were investigated, including increased uptake rate and increased biotransformation into a more toxic metabolite. Although the uptake rate was increased by more than 40%, the resulting increase in toxicity would be minimal as compared to the 400% decrease estimated to occur in EC50 values for the same Atrazine exposure (200 mg/L). Body residue analysis of midges exposed in vivo to Atrazine and chlorpyrifos mixtures for 96 h indicated that a larger amount of metabolites was generated in Atrazine treatments as compared to controls. Additionally, in vitro assays of microsomal proteins obtained from treated and control midges indicated that an increase in toxic metabolite (chlorpyrifos-O-analog) was generated in Atrazine-treated midges. Therefore, the increase in toxicity is thought to be due to an increase in biotransformation rates of the OPs, resulting in more O-analog within the organism. Keywords—Atrazine Organophosphate insecticides Mixtures Synergism Biotransformation

  • Impact of Atrazine on organophosphate insecticide toxicity
    Environmental Toxicology and Chemistry, 2000
    Co-Authors: J. B. Belden, Michael J. Lydy

    Abstract:

    Acute toxicity of selected organophosphorus insecticides (OPs; chlorpyrifos, methyl parathion, diazinon, and malathion) was determined for individual OPs and binary combinations of the OPs with Atrazine to larvae of the midge Chironomus tentans. Atrazine individually was not acutely toxic even at high concentrations (10,000 mg/L); however, the presence of Atrazine at much lower concentrations (40–200 mg/L) increased the toxicity of chlorpyrifos, methyl parathion, and diazinon. Atrazine did not increase the toxicity of malathion. Possible mechanisms for the synergistic toxicity found between Atrazine and chlorpyrifos were investigated, including increased uptake rate and increased biotransformation into a more toxic metabolite. Although the uptake rate was increased by more than 40%, the resulting increase in toxicity would be minimal as compared to the 400% decrease estimated to occur in EC50 values for the same Atrazine exposure (200 mg/L). Body residue analysis of midges exposed in vivo to Atrazine and chlorpyrifos mixtures for 96 h indicated that a larger amount of metabolites was generated in Atrazine treatments as compared to controls. Additionally, in vitro assays of microsomal proteins obtained from treated and control midges indicated that an increase in toxic metabolite (chlorpyrifos-O-analog) was generated in Atrazine-treated midges. Therefore, the increase in toxicity is thought to be due to an increase in biotransformation rates of the OPs, resulting in more O-analog within the organism

  • synergistic toxicity of Atrazine and organophosphate insecticides contravenes the response addition mixture model
    Environmental Toxicology and Chemistry, 1997
    Co-Authors: Pamela Papelindstrom, Michael J. Lydy

    Abstract:

    A toxic unit (TU) approach was used to test the response addition model for mixtures of pesticides with differing modes of action. Atrazine was tested in binary and ternary combinations with the organochlorine insecticide methoxychlor and organophosphate insecticide methyl-parathion. Atrazine was also tested in binary combinations with additional organophosphates. The TU for Atrazine was set slightly below its water solubility limits (TU = 20 ppm), which is well below its 96-h 50% effective concentration for the fourth instar of the midge, Chironomus tentans. In 96-h acute toxicity tests using C. tentans, Atrazine was found to produce synergistic (greater than additive) toxicity in a binary mixture with methyl-parathion. Less than additive toxicity was found for the combination of Atrazine with methoxychlor (likely due to the low TU assigned to Atrazine). The ternary combination of Atrazine + methyl-parathion + methoxychlor was found to be marginally synergistic. Results of toxicity tests with Atrazine in binary combinations with other organophosphates indicate more than additive toxicity for all compounds except mevinophos. Possible hypotheses are presented in an attempt to explain the noted synergistic relationship between Atrazine and various organophosphorous insecticides. These results suggest that the response addition model does not always accurately predict mixture toxicity for chemicals with differing modes of action.

Lawrence P Wackett – 2nd expert on this subject based on the ideXlab platform

  • Biodegradation of Atrazine by three transgenic grasses and alfalfa expressing a modified bacterial Atrazine chlorohydrolase gene
    Transgenic Research, 2014
    Co-Authors: Andrew Vail, Lawrence P Wackett, Ping Wang, Hirotaka Uefuji, Deborah A. Samac, Carroll P. Vance, Michael J. Sadowsky

    Abstract:

    The widespread use of Atrazine and other s-triazine herbicides to control weeds in agricultural production fields has impacted surface and groundwater in the United States and elsewhere. We previously reported the cloning, sequencing, and expression of six genes involved in the Atrazine biodegradation pathway of Pseudomonas sp. strain ADP, which is initiated by atzA, encoding Atrazine chlorohydrolase. Here we explored the use of enhanced expression of a modified bacterial Atrazine chlorohydrolase, p-AtzA, in transgenic grasses (tall fescue, perennial ryegrass, and switchgrass) and the legume alfalfa for the biodegradation of Atrazine. Enhanced expression of p-AtzA was obtained by using combinations of the badnavirus promoter, the maize alcohol dehydrogenase first intron, and the maize ubiquitin promoter. For alfalfa, we used the first intron of the 5′-untranslated region tobacco alcohol dehydrogenase gene and the cassava vein mosaic virus promoter. Resistance of plants to Atrazine in agar-based and hydroponic growth assays was correlated with in vivo levels of gene expression and Atrazine degradation. The in planta expression of p-atzA enabled transgenic tall fescue to transform Atrazine into hydroxyAtrazine and other metabolites. Results of our studies highlight the potential use of transgenic plants for bioremediating Atrazine in the environment.

  • Biodegradation of Atrazine in transgenic plants expressing a modified bacterial Atrazine chlorohydrolase ( atzA ) gene
    Plant Biotechnology Journal, 2005
    Co-Authors: Lin Wang, Lawrence P Wackett, Deborah A. Samac, Carroll P. Vance, Nir Shapir, Neil E. Olszewski, Michael J. Sadowsky

    Abstract:

    Summary Atrazine is one of the most widely used herbicides in the USA. Atrazine chlorohydrolase (AtzA), the first enzyme in a six-step pathway leading to the mineralization of Atrazine in Gram-negative soil bacteria, catalyses the hydrolytic dechlorination and detoxification of Atrazine to hydroxyAtrazine. In this study, we investigated the potential use of transgenic plants expressing atzA to take up, dechlorinate and detoxify Atrazine. Alfalfa, Arabidopsis thaliana and tobacco were transformed with a modified bacterial atzA gene, p -atzA, under the control of the cassava vein mosaic virus promoter. All transgenic plant species actively expressed p -atzA and grew over a wide range of Atrazine concentrations. Thin layer chromatography analyses indicated that in planta expression of p -atzA resulted in the production of hydroxyAtrazine. Hydroponically grown transgenic tobacco and alfalfa dechlorinated Atrazine to hydroxyAtrazine in leaves, stems and roots. Moreover, p -atzA was found to be useful as a conditional-positive selection system to isolate alfalfa and Arabidopsis transformants following Agrobacterium -mediated transformation. Our work suggests that the in planta expression of p -atzA may be useful for the development of plants for the phytoremediation of Atrazine-contaminated soils and soil water, and as a marker gene to select for the integration of exogenous DNA into the plant genome.

  • Field-scale remediation of Atrazine-contaminated soil using recombinant Escherichia coli expressing Atrazine chlorohydrolase
    Environmental Microbiology, 2000
    Co-Authors: Lisa C. Strong, Hugh Mctavish, Michael J. Sadowsky, Lawrence P Wackett

    Abstract:

    We performed the first field-scale Atrazine remediation study in the United States using chemically killed, recombinant organisms. This field study compared biostimulation methods for enhancing Atrazine degradation with a novel bioaugmentation protocol using a killed and stabilized whole-cell suspension of recombinant Escherichia coli engineered to overproduce Atrazine chlorohyrolase, AtzA. AtzA dechlorinates Atrazine, producing non-toxic and non-phytotoxic hydroxyAtrazine. Soil contaminated by an accidental spill of Atrazine (up to 29 000 p.p.m.) supported significant populations of indigenous microorganisms capable of Atrazine catabolism. Laboratory experiments indicated that supplementing soil with carbon inhibited Atrazine biodegradation, but inorganic phosphate stimulated Atrazine biodegradation. A subsequent field-scale study consisting of nine (0.75 m3) treatment plots was designed to test four treatment protocols in triplicate. Control plots contained moistened soil; biostimulation plots received 300 p.p.m. phosphate; bioaugmentation plots received 0.5% (w/w) killed, recombinant E. coli cells encapsulating AtzA; and combination plots received phosphate plus the enzyme-containing cells. After 8 weeks, Atrazine levels declined 52% in plots containing killed recombinant E. coli cells, and 77% in combination plots. In contrast, Atrazine levels in control and biostimulation plots did not decline significantly. These data indicate that genetically engineered bacteria overexpressing catabolic genes significantly increased degradation in this soil heavily contaminated with Atrazine.

Peter Burauel – 3rd expert on this subject based on the ideXlab platform

  • Transfer of Atrazine Degradation Capability To Mineralize Aged 14C-Labeled Atrazine Residues in Soils
    Journal of Agricultural and Food Chemistry, 2013
    Co-Authors: Nicolai David Jablonowski, Nils Borchard, Petra Zajkoska, Rosane Martinazzo, Jason L. Krutz, Georg Hamacher, Peter Burauel

    Abstract:

    The degradation of environmentally long-term aged (22 years) 14C-labeled Atrazine residues in soil stimulated by inoculation with Atrazine-adapted soil from Belgium, the United States (U.S.), and Brazil at two different moisture regimes (50% WHCmax/slurried conditions) was evaluated. Inoculation of the soil containing the aged 14C-labeled Atrazine residues with 5, 50, and 100% (w/w) Belgian, U.S., or Brazilian Atrazine-adapted soil increased 14C-Atrazine residue mineralization by a factor of 3.1–13.9, depending upon the amount of Atrazine-adapted soil inocula and the moisture conditions. Aged 14C-Atrazine residue mineralization varied between 2 and 8% for Belgian and between 1 and 2% for U.S. and Brazilian soil inoculum at 50% WHCmax but was increased under slurried conditions, accounting for 8–10% (Belgian soil), 2–7% (Brazilian soil), and 3% (American soil). The results show that an increased degradation of long-term aged 14C-labeled Atrazine residues is possible by the transfer of Atrazine-adapted soil…

  • Biochar-mediated [14C]Atrazine mineralization in Atrazine-adapted soils from Belgium and Brazil
    Journal of Agricultural and Food Chemistry, 2013
    Co-Authors: Nicolai David Jablonowski, Nils Borchard, Petra Zajkoska, Jesús D. Fernández-bayo, Rosane Martinazzo, A. E. Berns, Peter Burauel

    Abstract:

    Biochar addition to soil has been reported to reduce the microbial degradation of pesticides due to sorption of the active compound. This study investigated whether the addition of hardwood biochar alters the mineralization of (14)C-labeled Atrazine in two Atrazine-adapted soils from Belgium and Brazil at different moisture regimens. Biochar addition resulted in an equally high or even in a significantly higher Atrazine mineralization compared to the soils without biochar. Statistical analysis revealed that the extent of Atrazine mineralization was more influenced by the specific soil than by the addition of biochar. It was concluded that biochar amendment up to 5% by weight does not negatively affect the mineralization of Atrazine by an Atrazine-adapted soil microflora.

  • Metabolism and Persistence of Atrazine in Several Field Soils with Different Atrazine Application Histories
    Journal of Agricultural and Food Chemistry, 2010
    Co-Authors: Nicolai David Jablonowski, Rosane Martinazzo, Georg Hamacher, Ulrike Langen, Stephan Köppchen, Diana Hofmann, Peter Burauel

    Abstract:

    To assess the potential occurrence of accelerated herbicide degradation in soils, the mineralization and persistence of 14C-labeled and nonlabeled Atrazine was evaluated over 3 months in two soils from Belgium (BS, Atrazine-treated 1973−2008; BC, nontreated) and two soils from Germany (CK, Atrazine-treated 1986−1989; CM, nontreated). Prior to the experiment, accelerated solvent extraction of bulk field soils revealed Atrazine (8.3 and 15.2 μg kg−1) in BS and CK soils and a number of metabolites directly after field sampling, even in BC and CM soils without previous Atrazine treatment, by means of LC-MS/MS analyses. For Atrazine degradation studies, all soils were incubated under different moisture conditions (50% maximum soil water-holding capacity (WHCmax)/slurried conditions). At the end of the incubation, the 14C-Atrazine mineralization was high in BS soil (81 and 83%) and also unexpectedly high in BC soil (40 and 81%), at 50% WHCmax and slurried conditions, respectively. In CK soil, the 14C-Atrazine m…