Relationship between anaphase aberrations and carcinogenicity in the trout embryo microinjection assay.

An increased incidence of anaphase aberrations was observed in the tissues of rainbow trout embryos (Salmo gairdneri) within 96 hours of exposure to mitomycin [(MM) CAS: 50-07-7; 50 and 100 ng/embryo] and aflatoxin B1 [(AFB1) CAS: 1162-65-8; 13 and 25 ng/embryo] with the use of the trout embryo microinjection assay. High numbers of anaphase aberrations in embryos exposed to MM were associated with low mitotic indices, cell pyknosis, and high embryo mortalities. When the anaphase aberration data for embryos exposed to AFB1 were compared to previously reported carcinogenesis data from the microinjection assay, the incidence of anaphase aberrations in embryos did not show the same quantitative variations as the incidence of hepatic carcinomas in adult trout. While anaphase aberrations may be an indicator of the clastogenic effects of chemicals on fish embryos, it is unlikely that these aberrations can be used as an early indicator of a carcinogenic response in the trout embryo assay.