Meeting Abstract
For the majority of the last half of the twentieth century and into the early 2000s, tributyltin (TBT) was used as an antifoulant on boat hulls as well as in other products. It has recently been banned in numerous countries due to its endocrine disrupting effect on gastropods, wherein it causes imposex (induced growth of male reproductive organs on adult females). More recently, TBT has been investigated as an obesogenic endocrine disruptor via the peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ forms a heterodimer with the retinoid x receptor alpha (RXRα), and together, they induce a signaling cascade promoting adipogenesis. TBT is an agonist for this in mammals. However, its effects in other animal groups, including non-avian reptiles are unknown. The American alligator (Alligator mississippiensis) is a good animal for studying endocrine disruption because like all crocodilians, it exhibits temperature-dependent sex determination (TSD), which makes it more sensitive to endocrine signaling during development than humans and other non-TSD organisms. To investigate the “developmental origins of adult disease” hypothesis for diseases including those such as obesity and those associated with reproductive issues, developmental exposure needs to be investigated. Therefore, alligators were exposed in ovo to TBT prior to the thermosensitive period for TSD. Endpoints investigated include sex ratios and liver morphology as well as gonadal and hepatic gene expression. In vitro transactivation assays for PPARγ- RXRα were also completed to investigate specific receptor activation.
