Effects of tributyltin (TBT) on Xenopus tropicalis embryos at environmentally relevant concentrations

Tributyltin (TBT) has been widely used as a biocide in antifouling paints and is a known endocrine disrupting chemical. In this paper, we exposed embryos of Xenopus tropicalis to 50-400ngL(-1) tributyltin chloride. TBT significantly decreased the survival rate, reduced the body length and retarded the development of embryos after 24, 36 and 48h of exposure. These effects of TBT were concentration- and time-dependent. Embryos treated with TBT showed multiple malformations. The most obvious alterations were abnormal eyes, enlarged proctodaeum, narrow fins, and skin hypopigmentation. Enlarged proctodaeum and narrow fins were mainly observed after 36 and 48h of exposure. The loss of eye pigmentation or the absence of external eyes occurred after 24 and 36h of exposure, while extended lenses or edemas of eyes were more commonly observed after 48h of exposure. Additional malformations included: small anterior region of heads, pericardial edemas, enlarged trunks, and bent tails. These results suggested that TBT is very toxic to X. tropicalis embryos at environmentally relevant concentrations.