Using Zebrafish as a Model System for Studying the Transgenerational Effects of Dioxin

2,3,7,8 Tetrachlorodibenzo-p-dioxin (TCDD) has been associated with many disease states in humans. A rising concern is that exposure early in life can lead to adult toxicity and toxicity in subsequent generations. Juvenile zebrafish exposed to TCDD (50 pg/ml in water; 1 h exposure) at 3 and 7 weeks post fertilization showed toxicity only later in adulthood. We have maintained the offspring of these exposed F-0 fish to determine whether we could find adverse affects in the next two generations of F-1 and F-2 offspring. TCDD exposure produced a significantly higher female:male ratio in all three generations. Scoliosis-like axial skeleton abnormalities, not normally observed in controls, were present in the F-1 and F-2 generations descended from the treated F-0 founders. Egg release and fertilization success were reduced in the TCDD lineage F-1 and F-2 generations. This reduction in fertility in the TCDD lineage F-2 generation could be attributed to alterations in the F-2 males. Using zebrafish as a model allowed the simultaneous maintenance of different generations with relatively small space and costs. The zebrafish showed clear signs of transgenerational responses persisting into generations never directly exposed to TCDD.