Corrie, Lorissa

Project title: Dioctyl sodium sulfosuccinate: Dispersant, laxative and endocrine disruptor

Department: Biochemistry and Microbiology

Faculty supervisor: Dr. Caren Helbing

"Dioctyl sodium sulfosuccinate (DOSS) is an oil spill dispersant present in COREXIT used in the Deepwater Horizon oil spill and a common constituent of laxatives. Recent evidence has linked DOSS, a persistent contaminant in the environment, to the promotion of obesity and feminization through the disruption of the action of certain hormones including estrogen, but there are considerable knowledge gaps that remain on its human and wildlife health impacts. In particular, it is not known if DOSS affects thyroid hormone action.

Thyroid hormones play a critical role in regulating growth, development, and metabolism of all vertebrates. One of the most dramatic examples of the importance of thyroid hormones is the requirement for these hormones to drive the metamorphosis of a tadpole into a frog. Tadpole metamorphosis is an excellent model for studying the mechanisms of thyroid hormone action.

My project will investigate the effects of DOSS on thyroid hormone activity in American bullfrog tadpoles (Rana catesbeiana). In particular, it will examine the effects of DOSS on the expression of thyroid hormone-regulated genes. Premetamorphic R. catesbeiana tadpoles will be exposed to three environmentally realistic concentrations of DOSS in the presence or absence of thyroid hormones. Tail fin, olfactory epithelium, back skin and liver tissue will be collected, mRNA will be isolated, and reverse transcription-quantitative real time PCR will be used to analyze thyroid hormone responsive gene transcripts. This will indicate whether DOSS affects the normal thyroid hormone response and shed light on the environmental impact of this potential endocrine disruptor."