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12
cells, the Notch signaling pathway regulates the differentiation of these multipotent stem
cells (Ohlstein and Spradling 2006). A more recent finding related to intestine stem cell
differentiation suggests that Notch signaling and Notch ligand Delta level determine the
differentiation fate of daughter cells of intestine stem cells (Ohlstein and Spradling
2007). A high Delta level with strong Notch signaling results in enterocyte cells, while
weak Notch signaling results in enteroendocrine cells (Ohlstein and Spradling 2007).
Germline stem cells, intestine stem cells, the niches, and signal pathway that support and
regulate the stem cells provides us an invaluable model system for our longevity and
other studies.
Drosophila RNAi
RNA interference (RNAi) is a relatively new technique. However, because it is easy to
carry out and it is able to precisely knock down any gene in a sequence-specific manner,
in the last a few years, RNAi has become the predominant choice for decreasing the
expression level of a gene of interest in most model organisms.
When dsRNA segments are introduced into eukaryotic cells, if their sequence is
complementary to that of an endogenous gene, the expression of the endogenous gene
will be inhibited by a mechanism known as RNA interference (RNAi) (Fire, Xu et al.
1998; Fire 1999; Hunter 1999; Bosher and Labouesse 2000). The evolutionary origin of
RNAi remains unclear, but most researchers agree that it is most likely a defense
mechanism that protects the host organism from virus invasions or restricts the motility
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 22 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 12 cells, the Notch signaling pathway regulates the differentiation of these multipotent stem cells (Ohlstein and Spradling 2006). A more recent finding related to intestine stem cell differentiation suggests that Notch signaling and Notch ligand Delta level determine the differentiation fate of daughter cells of intestine stem cells (Ohlstein and Spradling 2007). A high Delta level with strong Notch signaling results in enterocyte cells, while weak Notch signaling results in enteroendocrine cells (Ohlstein and Spradling 2007). Germline stem cells, intestine stem cells, the niches, and signal pathway that support and regulate the stem cells provides us an invaluable model system for our longevity and other studies. Drosophila RNAi RNA interference (RNAi) is a relatively new technique. However, because it is easy to carry out and it is able to precisely knock down any gene in a sequence-specific manner, in the last a few years, RNAi has become the predominant choice for decreasing the expression level of a gene of interest in most model organisms. When dsRNA segments are introduced into eukaryotic cells, if their sequence is complementary to that of an endogenous gene, the expression of the endogenous gene will be inhibited by a mechanism known as RNA interference (RNAi) (Fire, Xu et al. 1998; Fire 1999; Hunter 1999; Bosher and Labouesse 2000). The evolutionary origin of RNAi remains unclear, but most researchers agree that it is most likely a defense mechanism that protects the host organism from virus invasions or restricts the motility |
