Document Type


Date of Degree Completion

Summer 2015

Degree Name

Master of Science (MS)



Committee Chair

Lixing Sun

Second Committee Member

April K. Binder

Third Committee Member

Joseph Lorenz

Fourth Committee Member

R. Steven Wagner


There are different sex-determining mechanisms in our environment, which are separated into two groups known as genotypic sex determination (GSD) and environmental sex determination. The most well-known mechanism in the ESD group is temperature-dependent sex determination (TSD). In this study, the presence of the Doublesex and mab-3-related Transcription Factor (Dmrt1) gene was observed during embryonic development in geckos with a TSD mechanism. To do this, I observed the rate of transcription of the Dmrt1 gene in the Gecko species Gekko japonicus. Pregnant geckos were caught around Nanjing, China. Once the females laid their eggs, the eggs were then randomly placed in one of three different temperature regimes (24°C, 28°C, 32°C). The embryos, the main target, were dissected at two points during development and total RNA was extracted. A relative rate of transcription of the Dmrt1 gene was assessed using quantitative PCR (qPCR). I was not able to quantify the use of the Dmrt1 gene between males and females. However, my study does not allow me to exclude the possibility that G. japonicus may use a GSD system with a TSD override, instead of the earlier proposed TSD system.