Genotoxic Pollutants Research Articles

Postlabeling analysis of carcinogen-DNA adducts in mussel, Mytilus galloprovincialis

The 32P-postlabeling analysis of DNA adducts formed in mussel digestive gland homogenates incubated with 2-aminofluorene (32 μ m) showed one major and one minor adduct in the range of 1 adduct per 1–4 × 10 8 nucleotides. The predominant adduct was found to be chromatographically similar to the known C8-aminofluorene-substituted guanine adduct. The metabolic activation of 2-aminofluorene was blocked in the presence of methimazole (470 μ m), a competitive inhibitor of FAD-containing monooxygenase. In contrast to 2-aminofluorene, benzo( a)pyrene-modified DNA either did not show any adduct or a very weak adduct spot (1 adduct per 1–4 × 10 9 nucleotides). The samples of DNA from mussel, carp and bream, which had no obvious exposure to pollutants, showed one to several weak ‘natural adducts’. The origin of these adducts is as yet undetermined. Since postlabeling assay enables measurement of carcinogen-DNA adducts formed with any, even unknown, chemicals from the composite environmental mixture of genotoxic pollutants, it may become a valuable tool for risk assessment also in marine environments.

Determination of genotoxic polycyclic aromatic hydrocarbons in a sediment from the Black River (Ohio).

Polycyciic aromatic hydrocarbons (PAH) have been identified as genotoxic pollutants in sediment from the Black River, Ohio, where a high incidence of hepatoma was observed in brown bull-head catfish (Ictalurus nebulosus). Subfractions of PAH based on the number of aromatic carbons were isolated from the PAH fraction of a Black River sediment extract. Ten subfractions were analyzed by capillary column gas chromatographymass spectrometry, tested for mutagenicity using the Ames assay, and tested for induction of unscheduled DNA synthesis (UDS) in primary rat hepatocytes. The Ames assay indicated significant mutagenic activity in fractions which contained PAH with 4–6 aromatic rings; the majority of the activity was found in the fraction composed of 5-ring compounds. UDS was also significant in the same fractions, although the greatest genotoxicity was observed in thecata-condensed andperi-condensed 4-ring fractions which contained a large amount of alkylated-PAH.