Effects of Triphenyltin Acetate on Survival, Hatching Success, and Liver Ultrastructure of Early Life Stages of Zebrafish (Danio rerio)

In order to evaluate the toxicity of the fungicide triphenyltin acetate (TPTA) on hatching, survival, morphology, and histology of early life stages of zebrafish (Danio rerio), newly fertilized eggs were exposed to concentrations of 0.5, 5, 25, 75, and 100 μg/liter TPTA for 96 h at 28±0.5°C. Embryos and larvae were kept under constant observation for up to 7 days and studied with respect to mortality and teratogenic effects as well as histological and cytological alterations in the liver as endpoints of sublethal toxicity of TPTA. Exposure to TPTA caused dose- and time-related effects with respect to all parameters investigated: (1) Hatching was delayed at concentrations ≥0.5 μg/liter TPTA; (2) mortality increased at ≥25 μg/liter TA after 96 h exposure, with TPTA toxicity being higher in larval than in embryonic stages; (3) from ≥25 μg/liter, larvae exhibited skeletal malformation, retarded yolk sac resorption, and edema in the heart and yolk sac regions; and (4) histo- and cytopathological alterations of larval liver included changes in nuclei and mitochondria as well as glycogen depletion from ≥0.5 μg/liter TPTA. The study thus demonstrates not only an elevated sensitivity of zebrafish embryos to TPTA in stages prior to hatching, but also the importance of continuous observation over extended periods after termination of the actual exposure for a comprehensive evaluation of the toxicity of chemical compounds.