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107
Drosophila embryos to knock down genes of interest, and to characterize their function
(Zappe, Fish et al. 2006). This technique involves an inverted repeat of a sequence
specific to the target gene, and clones the inverted repeat structure into a vector that
contains a conditional promoter (Allikian, Deckert-Cruz et al. 2002). The whole
construct is then injected into developing fly embryo to establish the transgenic lines that
bear the inverted repeat sequence, which can in turn be conditionally transcribed. By
using a conditional promoter to control transcription, when desired, the inverted repeat
will be transcribed, and the transcript will fold back on itself and become a dsRNA. The
dsRNA will then be recognized and processed by the Dicer and RISC machinery
described above, triggering the RNAi mechanism to knock down the target gene.
We believe that the technique of RNAi injection into the developing embryo has its
value. However, after the injection, it takes more than 10 days for the embryo to fully
develop into adult. It will also take another 10 days or so, depending on the genetic cross
design, to manifest the phenotype. When screening large number of genes, the workload
could be relatively heavy. And the project could thus become time-consuming.
Because of the inherent disadvantage of RNAi by embryo injection, some researchers
started to think of alternative routes for Drosophila RNAi. By taking advantage of
bacteria that express dsRNA, C.elegans researchers are able to feed them with dsRNA-expressing
bacteria to achieve RNAi easily (Fraser, Kamath et al. 2000). In 2001, the
Drosophila researchers started to inject dsRNA into adult Drosophila abdomen, trying
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 117 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 107 Drosophila embryos to knock down genes of interest, and to characterize their function (Zappe, Fish et al. 2006). This technique involves an inverted repeat of a sequence specific to the target gene, and clones the inverted repeat structure into a vector that contains a conditional promoter (Allikian, Deckert-Cruz et al. 2002). The whole construct is then injected into developing fly embryo to establish the transgenic lines that bear the inverted repeat sequence, which can in turn be conditionally transcribed. By using a conditional promoter to control transcription, when desired, the inverted repeat will be transcribed, and the transcript will fold back on itself and become a dsRNA. The dsRNA will then be recognized and processed by the Dicer and RISC machinery described above, triggering the RNAi mechanism to knock down the target gene. We believe that the technique of RNAi injection into the developing embryo has its value. However, after the injection, it takes more than 10 days for the embryo to fully develop into adult. It will also take another 10 days or so, depending on the genetic cross design, to manifest the phenotype. When screening large number of genes, the workload could be relatively heavy. And the project could thus become time-consuming. Because of the inherent disadvantage of RNAi by embryo injection, some researchers started to think of alternative routes for Drosophila RNAi. By taking advantage of bacteria that express dsRNA, C.elegans researchers are able to feed them with dsRNA-expressing bacteria to achieve RNAi easily (Fraser, Kamath et al. 2000). In 2001, the Drosophila researchers started to inject dsRNA into adult Drosophila abdomen, trying |
