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Microbial short-term assays with thiram in vitro
Abstract:
The fungicide thiram was assayed in the following tests in vitro, with and without metabolic activation: (1) prophage lambda induction of Escherichia coli K12; (2) repair test in Salmonella typhimurium (strains TA1538 and TA1978); (3) induction of gene mutations in Aspergillus nidulans (methA1 suppressor induction). Thiram was positive in the repair test and in the A. nidulans forward-mutation test (4-6 fold increase) in the absence of metabolic activation. A slight increase was observed in prophage lambda induction with thiram in the presence of the metabolic activation system.
Insights
The fungicide thiram showed genotoxicity in bacterial repair tests and Aspergillus mutation assays without metabolic activation. It also slightly increased prophage lambda induction with metabolic activation, indicating potential mutagenic activity.
Area of Science:
- Environmental toxicology
- Microbial genetics
- Chemical mutagenesis
Background:
- Fungicides are widely used in agriculture, necessitating toxicological evaluation.
- Thiram is a common fungicide with potential environmental and health impacts.
- Understanding the genotoxic potential of thiram is crucial for risk assessment.
Purpose of the Study:
- To assess the in vitro genotoxicity of the fungicide thiram.
- To evaluate thiram's effects on DNA repair and gene mutation in microbial systems.
- To investigate the role of metabolic activation in thiram's genotoxic activity.
Main Methods:
- In vitro assays including prophage lambda induction in Escherichia coli K12.
- Bacterial repair tests using Salmonella typhimurium strains TA1538 and TA1978.
- Gene mutation induction in Aspergillus nidulans (methA1 suppressor induction).
- Tests were conducted with and without metabolic activation.
Main Results:
- Thiram tested positive in the Salmonella typhimurium repair test.
- A 4-6 fold increase in forward mutations was observed in Aspergillus nidulans.
- Thiram induced prophage lambda in Escherichia coli K12 with metabolic activation.
- Genotoxicity was observed in the absence of metabolic activation.
Conclusions:
- Thiram exhibits genotoxic potential, demonstrated by its ability to induce DNA damage and mutations in microbial systems.
- The fungicide is mutagenic in bacterial repair and fungal mutation assays.
- Metabolic activation may influence the genotoxic effects of thiram.