2012- 21st Annual NC State Undergraduate Research Symposium

Session Time : 4/10/12 10:30 AM - 4/10/12 11:45 AM

Content Area : Zoology

Poster Appointment: , -

Student Presenters :
Grace Eunhye Lee Biology

Mentors and/or Co-Authors :
John Godwin Biology

Abstract Title : Iodothyronine deiodinase type II and possible significance in sex change in the Bluehead wrasse (Thalassoma bifasciatum)

Abstract :
In fishes, like many other vertebrates, thyroid hormones play a significant role in a wide range of physiological processes including development, basal metabolism, and homeostasis. Iodothyronine deiodinase type II (Dio2) enzyme regulates thyroid hormone levels by converting T₄ to the more active T₃. In this study, we examined Dio2 expression in the Bluehead wrasse (Thalassoma bifasciatum), a female-to-male sex changing fish. When a terminal phase male is not present, the largest female will undergo sex change and become the new terminal phase male. Initial phase males and females are phenotypically similar with a yellow head and body and a white underside. Some initial phase males can also have white bars that break up the midlateral stripe forming a series of blackish and grayish blotches. The terminal phase males are much larger in size with a blue head followed by two dark vertical stripes separated by a white bar. Dio2 may play a role in Bluehead wrasse sex change mechanisms by altering thyroid hormone levels and metabolic rates. We performed non-radioactive in situ hybridization to reveal if and where Dio2 expression occurs in the brain and counted reads from high-throughput RNA-Seq data to obtain an estimate of potential differences in expression between terminal phase males and females. Although the read counts from high-throughput RNA-Seq reads only reported rough estimates, the results did show a potential difference in expression between terminal phase male and female Bluehead wrasse gonads and the brain. Overall, this study is an initial step to further detailed studies examining the possible relationship between Dio2 enzyme rates and sex change in the Bluehead wrasse.