Meeting Abstract
The American alligator (Alligator mississippiensis) exhibits temperature-dependent sex determination (TSD), in which incubation temperatures during thermosensitive period (TSP) in embryonic development determine sex of the offspring. Hormone signals also play a critical role in TSD, and exposure to exogenous endocrine active compounds during TSP can override the effects of temperature. Both natural estrogens and xenoestrogens can lead to sex reversal and induce female development, even when eggs are incubated at a male-producing temperature. Since A. mississippiensis is a long-lived, apex predator that does not migrate far during its lifetime, it is a great sentinel species to investigate chronic exposure to environmental contaminants, including endocrine disrupting contaminants (EDCs). During the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, the dispersant, Corexit 9500, was applied to the surface water and at the broken wellhead to dissolve the oil spill. Although studies have been conducted on toxicity, there has been limited research on the sublethal effects of Corexit 9500. We found that Corexit 9500 induced transactivation via American alligator estrogen receptor 1 (ESR1) on hormone receptor reporter gene assays in vitro, and could be an EDC. Further, alligator eggs were exposed to Corexit 9500 at 0.25, 2.5 and 25 mg/g egg weight during TSP to investigate the potential endocrine disruption and effects on gonadal development in the American alligator in ovo. Exposures to Corexit in ovo at these doses did not affect the viability at hatch-out. Further analyses of gonadal development in the alligators exposed to Corexit 9500 in ovo will be reported.
