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The Mechanisms and Effects of the Plant Activation of Chemicals in the Environment

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Final technical rept. 15 Sep 1988-30 Sep 1991

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Plant activation is the process by which promutagenic agents are activated into mutagens by plant systems. With the widespread use of agricultural chemicals on crop plants and with the global exposure of plants to pollutants, the possibility exists that plant-activated agents may be introduced into the human food chain. The plant cellmicrobe coincubation assay uses cultured plant cell suspensions as the activating system and bacteria or yeast cells as the genetic indicator organism. After a treatment time, the microbes are plated on selective medium. In this way the activation system and the genetic system can be independently studied. In addition the viability of the plant cells and the microbial cells can be independently determined so that the toxicity of a test agent can be evaluated. Using cytochrome P-450 monooxygenase, and peroxidase inhibitors we are studying the biochemical mechanisms of plant activation of environmental contaminants especially aromatic amines. We developed a model of the TX1-cell activation of aromatic amines. The model integrates our data into a mechanistic framework and serves as a foundation for new experimental designs. The model has seven components. They are, 1 the aromatic amine R-NH2 is transported into the plant TX1 cell, 2 TXl intracellular peroxidase oxidizes the molecule R-NHOH, 3 the metabolite is conjugated to a macromolecule R-NHOH-conjugate, 4 the amine-conjugate is secreted into the extracellular medium, 5 the conjugate is absorbed by the bacterial tester strain TA98, 6 the molecule may be deconjugated and is acetylated R-NHO-COCH3 and deacetylated by the bacterial acetyl-Co A nhydroxyarylainine 0-acetyltransferase, and 7 the deacetylation results in a highly reactive nitrenium ion R-NH.

Subject Categories:

  • Biochemistry
  • Biology
  • Medicine and Medical Research
  • Pesticides Pollution and Control

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