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18
One can also rely on large scale RNAi projects to predict the molecular functions of new
genes. A few reports already demonstrate the successful application of this novel but
powerful approach on Drosophila on a large scale (Mathey-Prevot and Perrimon 2006;
Dietzl, Chen et al. 2007). By knocking down the expression of many different genes
individually and culturing the flies into adulthood, one can directly observe the
corresponding phenotypes in any life stage. With easy access to mutant flies, researchers
can also design genetic crosses between different knock-down mutant strains to
investigate the relations between the genes in the same or different regulation pathways.
However, as with all other molecular biology techniques, RNAi has disadvantages.
RNAi simulates a loss-of-function mutation. It does not allow the over-expression of the
target gene. Therefore it is difficult to obtain the gain-of-function mutant phenotype by
only performing RNAi mutations.
Our lab devised a novel approach to generate a large quantity of random mutants that
can over-express many genes individually. With this system, gain-of-function mutation
phenotypes can be readily generated and observed (Landis, Bhole et al. 2001). The
system takes advantage of P-element mutagenesis and the tet-on system to create the
concept of PdL mutagenesis. By using transposase to excise and insert the PdL
conditional promoter into random locations in the genome (Figure 1), a random gene can
be over-expressed, and its gain-of-function phenotype can be studied. Given enough
mutants, one can cover almost the whole genome to study the gain-of-function mutant
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 28 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 18 One can also rely on large scale RNAi projects to predict the molecular functions of new genes. A few reports already demonstrate the successful application of this novel but powerful approach on Drosophila on a large scale (Mathey-Prevot and Perrimon 2006; Dietzl, Chen et al. 2007). By knocking down the expression of many different genes individually and culturing the flies into adulthood, one can directly observe the corresponding phenotypes in any life stage. With easy access to mutant flies, researchers can also design genetic crosses between different knock-down mutant strains to investigate the relations between the genes in the same or different regulation pathways. However, as with all other molecular biology techniques, RNAi has disadvantages. RNAi simulates a loss-of-function mutation. It does not allow the over-expression of the target gene. Therefore it is difficult to obtain the gain-of-function mutant phenotype by only performing RNAi mutations. Our lab devised a novel approach to generate a large quantity of random mutants that can over-express many genes individually. With this system, gain-of-function mutation phenotypes can be readily generated and observed (Landis, Bhole et al. 2001). The system takes advantage of P-element mutagenesis and the tet-on system to create the concept of PdL mutagenesis. By using transposase to excise and insert the PdL conditional promoter into random locations in the genome (Figure 1), a random gene can be over-expressed, and its gain-of-function phenotype can be studied. Given enough mutants, one can cover almost the whole genome to study the gain-of-function mutant |
