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A comparative study on selected chemical carcinogens for chromosome malsegregation, mitotic crossing-over and forward

R Crebelli, D Bellincampi, G Conti

    Mutation Research
    |November 1, 1986
    PubMed

    Insights

    Ten "false negative" chemical carcinogens were tested for genotoxicity in Aspergillus nidulans. Benzene, ethylenethiourea, and urethane induced mitotic segregation, but not mutations or crossing-over.

    Area of Science:

    • Genetics
    • Toxicology
    • Mycology

    Background:

    • Bacterial mutagenicity assays are standard for detecting genotoxic carcinogens.
    • Some known chemical carcinogens yield false-negative results in these bacterial tests.
    • Investigating genotoxic activity in alternative model systems is crucial.

    Purpose of the Study:

    • To evaluate the genotoxic potential of ten "false negative" chemical carcinogens using the mould Aspergillus nidulans.
    • To assess the induction of forward mutations, mitotic crossing-over, and chromosome malsegregation.

    Main Methods:

    • Utilized Aspergillus nidulans as a model organism for genotoxicity testing.
    • Scored for forward mutations (methionine suppressors).
    • Assessed mitotic crossing-over and chromosome malsegregation (non-disjunction).

    Main Results:

    • Benzene, ethylenethiourea, and urethane induced mitotic segregation, indicating chromosome malsegregation.
    • These three compounds did not increase the frequency of forward mutations or mitotic crossing-over.
    • Acetamide, amitrole, dieldrin, heptachlor epoxide, nitrilotriacetic acid, p,p'-DDT, and thiourea showed no genotoxic effects in this assay.

    Conclusions:

    • Aspergillus nidulans can detect genotoxic activity (mitotic segregation) missed by bacterial mutagenicity assays.
    • Benzene, ethylenethiourea, and urethane possess genotoxic properties not evident in standard bacterial tests.
    • The study highlights the importance of using multiple test systems for comprehensive genotoxicity assessment.

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