University of Utah Undergraduate Research Abstracts, Volume 2, Spring 2002

Functional Analysis of the Drosophila Hormone Receptor DHR78

Functional Analysis Of The Drosophila Hormone Receptor DHR78 Members of the nuclear receptor superfamily act as hormone-regulated transcription factors, and control multiple aspects of growth, development, and metabolism. The Drosophila nuclear receptor DHR78, whose ligand is unknown, is proposed to regulate the genetic cascade preparing larvae for metamorphosis. Dhr78 mutants arrest during the larval stage prior to metamorphosis and display defects in the trachea including breaks and necrosis, malformed taenidia, and improper molting. Interestingly, these phenotypes are similar to the phenotypes of larvae deficient for Eclosion Hormone, one of the peptide hormones involved in triggering ecdysis behavior in insects. I am studying the functions of DHR78 in the fruit fly Drosophila melanogaster. My data using germline clonal analysis indicate that DHR78 is not required for oogenesis or embryonic development. While further characterizing the tracheal defects, I noticed that tracheal air-filling in mutants during the first- to second- larval instar ecdysis is incomplete. I have also created transgenic flies that express double-stranded DHR78 RNA in response to heat treatment and constructs that express in a tissue-specific manner. The presence of double-stranded RNA has been shown to degrade the corresponding mRNA in vivo. I will use this RNAi technique to selectively inhibit DHR78 function prior to the molts and during the mutant lethal phase. This will help me to decipher whether the larvae are dying as a result of dysfunctional trachea or due to a missing genetic cascade leading to metamorphosis. John M. Astle Class Standing: Junior Major: Biology E-mail: [e-mail] Faculty Sponsor: Tatiana Kozlova Department of Human Genetics E-mail: [e-mail]. utah.edu Faculty Sponsor: Carl Thummel Department of Human Genetics E-mail: Carl.thummel@ genetics.utah.edu