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101
Discussion
The experiment was performed successfully, as demonstrated by the negative and
positive control groups. The negative Or-R flies did not fluoresce at all in any of the
time points (Figure 19A). The lack of GFP meant that GAL4 was not produced in the
Or-R cross progeny flies, as was expected. Actin5C is a ubiquitous promoter that is
extensively used when high expression levels of a gene of interest are required (Ford,
Hoe et al. 2007). As can be seen in the 10 day and 30 day time point pictures, the
fluorescence was relatively strong at 10 days (Figure 19B), but disappeared in later time
points. This could suggest that the expression of Actin5C in the fly gut decreases during
fly aging. Many researchers have used this promoter as a fairly standard method to
express genes of interest ubiquitously in all tissues (Bieschke, Wheeler et al. 1998; Sun
and Tower 1999; Ford, Hoe et al. 2007). From the results of this experiment, it is still
unclear whether or not the expression level of Actin5C specifically in fly gut remains
stable throughout fly lifespan. This issue deserves further investigation for anyone who
would like to express their gene of interest specifically in Drosophila gut.
3 out of 10 crosses showed no fluorescence signal in any of the time points, including
CG13377-GAL4, dawdle-GAL4, and lola-GAL4 (Figure 19C, E, J.). The lack of GFP
signal suggests that although these genes may express abundantly in Drosophila ovary
stem cells (Morris Waskar unpublished data), their expression in Drosophila gut remains
low throughout the fly lifespan.
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 111 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 101 Discussion The experiment was performed successfully, as demonstrated by the negative and positive control groups. The negative Or-R flies did not fluoresce at all in any of the time points (Figure 19A). The lack of GFP meant that GAL4 was not produced in the Or-R cross progeny flies, as was expected. Actin5C is a ubiquitous promoter that is extensively used when high expression levels of a gene of interest are required (Ford, Hoe et al. 2007). As can be seen in the 10 day and 30 day time point pictures, the fluorescence was relatively strong at 10 days (Figure 19B), but disappeared in later time points. This could suggest that the expression of Actin5C in the fly gut decreases during fly aging. Many researchers have used this promoter as a fairly standard method to express genes of interest ubiquitously in all tissues (Bieschke, Wheeler et al. 1998; Sun and Tower 1999; Ford, Hoe et al. 2007). From the results of this experiment, it is still unclear whether or not the expression level of Actin5C specifically in fly gut remains stable throughout fly lifespan. This issue deserves further investigation for anyone who would like to express their gene of interest specifically in Drosophila gut. 3 out of 10 crosses showed no fluorescence signal in any of the time points, including CG13377-GAL4, dawdle-GAL4, and lola-GAL4 (Figure 19C, E, J.). The lack of GFP signal suggests that although these genes may express abundantly in Drosophila ovary stem cells (Morris Waskar unpublished data), their expression in Drosophila gut remains low throughout the fly lifespan. |
