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7
target site, the tetracycline operator (tetO). This binding occurs only in the presence of
tetracycline, or one of its derivatives, such as doxycycline (DOX). When the DNA
binding capability of rtR is coupled to the transcription activation capability of herpes
virus protein VP16, we obtain the transactivator protein rtTA. Previous research
suggested that, in mammals, rtTA turned on transcription of a gene downstream of a
tetO sequence in a DOX-dependent manner. The research demonstrated that tet-on
system also worked efficiently in Drosophila, as indicated by the successful induction of
beta-gal by up to 100 fold (Bieschke, Wheeler et al. 1998).
In later reports, the same group of researchers placed the DOX-inducible promoter, a
combination of the tetO operator and the hsp70 core promoter, within a transposable P-element,
creating a DOX-inducible transposable promoter named PdL (Landis, Bhole et
al. 2001). The promoter, when it is mobilized to a new chromosomal position by the
transposase, is able to induce transcription of a gene downstream of the insertion site in
a DOX-dependent manner. This novel method gave the scientists a powerful tool to
generate many different transgenic Drosophila strains simultaneously with each one
being able to over-express a gene-of-interest specifically in any development stage. The
induction requires only a tiny amount of the DOX chemical in the Drosophila food
(Landis, Bhole et al. 2001). Given enough independent crosses, PdL-based mutagenesis
is able to induce a large fraction of the genes in Drosophila, thus making possible the
investigation of the over-expression phenotypes of a significant fraction of the 14,000
Drosophila genes.
Object Description
| Title | Characterization of Drosophila longevity and fecundity regulating genes |
| Author | Li, Yishi |
| Author email | yishili@usc.edu; yishili@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Molecular & Computational Biology |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-08-19 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-31 |
| Advisor (committee chair) | Tower, John |
| Advisor (committee member) |
Finkel, Steven E. Aparicio, Oscar Martin Longo, Valter D Comai, Lucio |
| Abstract | The regulation of Drosophila melanogaster longevity and fecundity involves many factors. Longevity is governed by oxidative stress, stem cell loss, dietary restriction, the insulin/IGF-1 pathway, and other factors. Fecundity is also regulated by multiple tissues and factors, including the germline stem cells and stem cell niche, the fat body, yolk proteins, and sex peptides. The fecundity of wild type female Drosophila gradually declines during aging, suggesting a common pathway regulating longevity and fecundity machinery. Since both mechanisms involve multiple factors, sorting through the Gordian’s knot is a formidable task. Using a PdL mutagenesis approach, I screened for a specific phenotype in thousands of independent mutant strains to examine both regulatory networks simultaneously. Two novel genes, magu and hebe, were identified and characterized to regulate longevity and fecundity. While Drosophila lifespan was extended upon the induction of these genes, fecundity increase requires that the gene induction be in an ideal range to show the expected phenotypic change. I also performed several other projects, including studying the lifespan extension effect of dIAP2, characterization of a Drosophila gut driver strain, and intra-abdominal RNAi injection in adult Drosophila. These projects provided us insight on longevity, fecundity, anti-apoptosis, stem cell biology, RNAi and other aspects of Drosophila research. In sum, Drosophila melanogaster, as a model organism for molecular biology and genetics study, will continue to contribute to the scientific community. |
| Keyword | Drosophila; longevity; fecundity |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1735 |
| Contributing entity | University of Southern California |
| Rights | Li, Yishi |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Li-2382 |
| Archival file | uscthesesreloadpub_Volume44/etd-Li-2382.pdf |
Description
| Title | Page 17 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 7 target site, the tetracycline operator (tetO). This binding occurs only in the presence of tetracycline, or one of its derivatives, such as doxycycline (DOX). When the DNA binding capability of rtR is coupled to the transcription activation capability of herpes virus protein VP16, we obtain the transactivator protein rtTA. Previous research suggested that, in mammals, rtTA turned on transcription of a gene downstream of a tetO sequence in a DOX-dependent manner. The research demonstrated that tet-on system also worked efficiently in Drosophila, as indicated by the successful induction of beta-gal by up to 100 fold (Bieschke, Wheeler et al. 1998). In later reports, the same group of researchers placed the DOX-inducible promoter, a combination of the tetO operator and the hsp70 core promoter, within a transposable P-element, creating a DOX-inducible transposable promoter named PdL (Landis, Bhole et al. 2001). The promoter, when it is mobilized to a new chromosomal position by the transposase, is able to induce transcription of a gene downstream of the insertion site in a DOX-dependent manner. This novel method gave the scientists a powerful tool to generate many different transgenic Drosophila strains simultaneously with each one being able to over-express a gene-of-interest specifically in any development stage. The induction requires only a tiny amount of the DOX chemical in the Drosophila food (Landis, Bhole et al. 2001). Given enough independent crosses, PdL-based mutagenesis is able to induce a large fraction of the genes in Drosophila, thus making possible the investigation of the over-expression phenotypes of a significant fraction of the 14,000 Drosophila genes. |
