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 (TP TA) on hatching, survival, morphology, and histology of early life stages o f zebrafish (Danio rerio), newly fertilized eggs were exposed to concentrat ions of 0.5, 5, 25, 75, and 100 mu g/liter TPTA for 96 h at 28 +/- 0.5 degr ees 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 su blethal toxicity of TPTA. Exposure to TPTA caused dose- and time-related ef fects with respect to all parameters investigated: (1) Hatching was delayed at concentrations greater than or equal to 0.5 mu g/liter TPTA; (2) mortal ity increased at greater than or equal to 25 mu g/liter TA after 96 h expos ure, with TPTA toxicity being higher in larval than in embryonic stages; (3 ) from greater than or equal to 25 mu g/liter, larvae exhibited skeletal ma lformation, retarded yolk sac resorption, and edema in the heart and yolk s ac regions; and (4) histo- and cytopathological alterations of larval liver included changes in nuclei and mitochondria as well as glycogen depletion from greater than or equal to 0.5 mu g/liter TPTA. The study thus demonstra tes 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 comprehensi ve evaluation of the toxicity of chemical compounds. (C) 1999 Academic Pres s.