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84
of the rtTA transcription activation machinery, reducing trans-activation of the transgene
and thereby reducing the lifespan extension effects that were observed in the first round.
The design of the third round experiment was a completely novel approach. By adding
DOX during the larval development stage, the experiment took full advantage of the
Tet-on system, which is able to express the gene of interest at any desired time point.
The expression of dIAP2 in the larvae could provide an anti-apoptotic effect and in turn
be beneficial to Drosophila longevity even if the overexpression is not continued into
adulthood. This hypothesis was confirmed by the increased lifespan of both male and
female groups in this round. The decreased lifespan effect in both male and female
groups and in both control strains (Or-R wild type and W1118) may suggest a
deleterious effect of DOX on the developing larvae. Although there are no previous
reports of such an effect (Bieschke, Wheeler et al. 1998; Landis, Bhole et al. 2001; Ford,
Hoe et al. 2007), the significantly decreased lifespan of those adults could be concerning
to Drosophila researchers looking to apply DOX on developing larvae for longevity
research.
Conclusion
The first two rounds of lifespan assays in the dIAP2 project gave a complicated and
somewhat intriguing result, consisting of a successful lifespan extension phenotype in
the first round that disappeared in the second round. The vanishing of the lifespan
extension could be due to the degradation of DOX reagents by abnormal environment
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 94 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 84 of the rtTA transcription activation machinery, reducing trans-activation of the transgene and thereby reducing the lifespan extension effects that were observed in the first round. The design of the third round experiment was a completely novel approach. By adding DOX during the larval development stage, the experiment took full advantage of the Tet-on system, which is able to express the gene of interest at any desired time point. The expression of dIAP2 in the larvae could provide an anti-apoptotic effect and in turn be beneficial to Drosophila longevity even if the overexpression is not continued into adulthood. This hypothesis was confirmed by the increased lifespan of both male and female groups in this round. The decreased lifespan effect in both male and female groups and in both control strains (Or-R wild type and W1118) may suggest a deleterious effect of DOX on the developing larvae. Although there are no previous reports of such an effect (Bieschke, Wheeler et al. 1998; Landis, Bhole et al. 2001; Ford, Hoe et al. 2007), the significantly decreased lifespan of those adults could be concerning to Drosophila researchers looking to apply DOX on developing larvae for longevity research. Conclusion The first two rounds of lifespan assays in the dIAP2 project gave a complicated and somewhat intriguing result, consisting of a successful lifespan extension phenotype in the first round that disappeared in the second round. The vanishing of the lifespan extension could be due to the degradation of DOX reagents by abnormal environment |
