Award Date


Degree Type


Degree Name

Doctor of Philosophy in Biological Sciences


Life Sciences

First Committee Member

Andrew Andres, Chair

Second Committee Member

Frank van Breukelen

Third Committee Member

Jeffery Shen

Fourth Committee Member

Laurel Raftery

Graduate Faculty Representative

Ernesto Abel-Santos

Number of Pages



Cholesterol is the precursor to a unique class of lipophilic signaling molecules called steroid hormones that initiate the development of sexual characteristics, reactions to stress, and maintenance of metabolism, among many other functions. Although much progress has been made in understanding the function of these signaling hormones, we do not fully understand how a single steroid can cause many distinct, tissue-specific responses. Drosophila melanogaster is an effective model for understanding steroid hormone action because of its simplicity. The steroid molting hormone 20-hydroxyecdysone (hereafter, 20E) is the primary active steroid in Drosophila and mediates not only larval molts and the emergence of a sexually mature adult, but also is an effector of many other tissue-specific actions from the embryonic to larval stages and into adulthood. An effective approach for studying hormone signaling is to use molecular genetics in which genes (that have roles in 20E-signaling pathways) are overexpressed or silenced in a specific tissue at a defined time during development. Even more, Drosophila is a tractable model organism with many tools that are widely available, and large-scale genetic screens are easily executed. We chose to focus on the salivary gland of larval Drosophila as a primary model for 20E signaling in that several specific, measurable responses to the steroid occur at different times during development. Using this model system, my dissertation research was centered on two major aims: 1) identify genes in the 20E-regulated process of glue secretion in the larval salivary gland; and 2) test the hypothesis that an ATP-Binding Cassette (ABC) transporter, E23, participates in a negative feedback loop that acts directly on the hormone 20E.


Abc transporter; Ashburner model; ATP-binding cassette transporters; Biological sciences; Choline acetyltransferease; Drosophila; Drosophila melanogaster; E23; Hydroxyecdysone; Larval salivary gland; Steroid hormones


Biochemistry | Biology | Genetics | Genetics and Genomics

File Format


Degree Grantor

University of Nevada, Las Vegas




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