Activation of mammalian carcinogens to bacterial mutagens by microsomal enzymes from a pelecypod mollusk, Mercenaria mercenaria

Abstract

Several kinds of neoplastic diseases have been described in mollusks collected from the field. The etiology of these lesions is unknown; however, the involvement of chemical carcinogens has been suggested. Experimental models for chemically-induced neoplasia in bivalves have yet to be developed. We have obtained data which suggest that aromatic amines may be more appropriate candidates than polycyclic aromatic hydrocarbons for putative molluscan carcinogens. Digestive gland enzymes from a bivalve mollusk, Mercenaria mercenaria, were found to be able to convert aromatic amines to frameshift mutagens as detected by the Ames Salmonella tester strains. Extensive mutagenesis was obtained with 2-aminoanthracene, 2-aminofluorene, 2-acetylaminofluorene and 4-amino-trans-stilbene which are all mammalian procarcinogens. Mutagenic activation of benzo[a]pyrene and 3-methylcholanthrene was minimal. Low levels of aromatic amine-activating enzyme(s) were found in all tissues examined, but activity was greatest in the digestive gland. Enzymatic activity was heat-labile, NADPH-dependent, and apparently not inducible by polychlorinated biphenyls (Aroclor 1254).