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Mutations Increasing Drosophila melanogaster Life Span

ABSTRACT: ABSTRACT MAGWIRE, MICHAEL MAHLON. Mutations Increasing Drosophila melanogaster Life Span. (Under the direction of Trudy F. C. Mackay.) Better living conditions and advances in medicine have made it possible for humans to live considerably longer than before. This has uncovered many health problems associated with age. By identifying genes involved in the limitation of life span, we may better understand the processes that lead to aging. In model organisms, we can use mutagenesis to discover mutations that increase life span, and hence infer that the wild-type allele limits life span by some means. We have assessed longevity in a collection of 1332 co-isogenic gene-trap P-element insertion lines and determined changes in life span of each insert line relative to the corresponding control line. Significant lines were determined via two different methods of analysis: A 95% confidence interval was established based on deviations of the mutant life spans from the controls and Dunnett’s two tailed t-tests were used to examine differences between mutant and control in each individual block. Based on the 95% confidence interval, 139 inserts displayed an increase in life span and 194 inserts a decrease. Using Dunnett’s, 70 lines increased in life span, while 270 decreased in life span. An additional 48 increased longevity lines were close enough to meeting Dunnett’s criteria to be considered for additional investigation. Combining these two analyses, we chose 83 inserts associated with increased life span for a secondary screen using an additional twelve replicates. 58 of these lines remained significant. We have determined the P-element insertion site for 50 of these lines. Starvation resistance, chill coma recovery time and climbing activity were measured on the lines remaining significant after the the secondary screen to identify pleiotropic effects. A positive correlation was found for males between life span and starvation resistance as well as between life span and chill coma recovery. Females only displayed a correlation between life span and chill coma recovery, which was negative. None of the lines indicated increased fitness for all phenotypes, indicating there may be some type of trade-off. There also appears to be a lot of pleiotropic variation depending on background and sex. Ten of the lines, all with the same parental background, were chosen for a half-diallel cross to identify epistasis between the mutants. There were substantial epistatic interactions between all ten lines. Furthermore, males and females displayed vastly different patterns of epistasis, again indicating major differences in life span regulation between the sexes. Finally, a subset of seven of the lines used in the epistatic study, in addition to the corresponding parental control, were chosen for microarray analysis to look for possible pathways and novel genes involved in increasing life span. 1,996 probe sets were significant at a false discovery rate q-value threshold of q < 0.0001. Tukeys tests were carried out for these probe sets to determine how each of the seven mutant backgrounds differed compared to the control and each other. In addition, each mutant background was compared individually with the control to identify any changes in expression. Gene ontologies were determined for each of the lines to identify over-represented biological functions which would indicate possible longevity pathways. Dozens of pathways were suggested, including several novel pathways. Keywords: Genetic (P-element insertion) modification and comparison to control line

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE8775 | GEO | 2008/08/01

SECONDARY ACCESSION(S): PRJNA102065

REPOSITORIES: GEO

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Project description:Mutations Increasing Drosophila melanogaster; Life Span. (Under the direction of Trudy F. C. Mackay.); Better living conditions and advances in medicine have made it possible for; humans to live considerably longer than before. This has uncovered many; health problems associated with age. By identifying genes involved in the; limitation of life span, we may better understand the processes that lead to aging. In model organisms, we can use mutagenesis to discover mutations that; increase life span, and hence infer that the wild-type allele limits life span by some means. We have assessed longevity in a collection of 1332 co-isogenic gene-trap; P-element insertion lines and determined changes in life span of each insert line relative to the corresponding control line. Significant lines were determined via two different methods of analysis: A 95% confidence interval was established based on deviations of the mutant life spans from the controls and Dunnettâs two tailed t-tests were used to examine differences between mutant and control in each individual block. Based on the 95% confidence interval, 139 inserts displayed an increase in life span and 194 inserts a decrease. Using Dunnettâs, 70 lines increased in life span, while 270 decreased in life span. An additional 48 increased longevity lines were close enough to meeting Dunnettâs criteria to be considered for additional investigation. Combining these two analyses, we chose 83 inserts associated with increased life span for a secondary screen using an; additional twelve replicates. 58 of these lines remained significant. We have; determined the P-element insertion site for 50 of these lines. Starvation resistance, chill coma recovery time and climbing activity were; measured on the lines remaining significant after the the secondary screen to identify pleiotropic effects. A positive correlation was found for males between life span and starvation resistance as well as between life span and chill coma recovery. Females only displayed a correlation between life span and chill coma recovery, which was negative. None of the lines indicated increased fitness for all phenotypes, indicating there may be some type of trade-off. There also appears to be a lot of pleiotropic variation depending on background and sex. Ten of the lines, all with the same parental background, were chosen for a; half-diallel cross to identify epistasis between the mutants. There were; substantial epistatic interactions between all ten lines. Furthermore, males and females displayed vastly different patterns of epistasis, again indicating major differences in life span regulation between the sexes. Finally, a subset of seven of the lines used in the epistatic study, in; addition to the corresponding parental control, were chosen for microarray; analysis to look for possible pathways and novel genes involved in increasing life span. 1,996 probe sets were significant at a false discovery rate q-value; threshold of q < 0.0001. Tukeys tests were carried out for these probe sets to determine how each of the seven mutant backgrounds differed compared to the control and each other. In addition, each mutant background was compared individually with the control to identify any changes in expression. Gene ontologies were determined for each of the lines to identify over-represented biological functions which would indicate possible longevity pathways. Dozens of pathways were suggested, including several novel pathways. Experiment Overall Design: We used seven mutant lines homozygous for a P-element insertion and a control line. All lines were isogenic other than the P-element insert. Males and females were done separately with two replicates for a total of 32 arrays.

Project description:One of the most important issues in the study of aging is to discover compounds with longevity-promoting activity and to unravel their underlying mechanisms. Queen honey bees are continuously fed royal jelly (RJ), and they live more than 10 times longer than hive workers, derived from the same diploid genome, which are fed it only for a short period of time during their larval stages. Therefore, RJ is likely to contain longevity-promoting agents for queens. RJ has been reported to possess diverse pharmacological properties. Furthermore, protease-treated RJ (pRJ) has additional beneficial activities. How RJ and pRJ exert these effects and which components in them play a critical role is largely unknown. The evolutionally conserved mechanisms that control lifespan have been indicated. The nematode Caenorhabditis elegans has been widely used for study of aging and longevity, due to its relatively short lifespan and well-established genetic pathways. The purpose of the present study was to elucidate whether RJ and its related substances contain the life span-extending activity in C. elegans and to obtain some insight into the active agents and their mechanisms. We found that both RJ and pRJ extended the lifespan of C. elegans. The life span-extending activity of pRJ was enriched by ODS column chromatography (pRJ-Fraction 5). pRJ-Fr. 5 extended the life span partly by acting through the FOXO transcription factor DAF-16, the activation of which is known to promote longevity in C. elegans by reducing insulin/IGF-1 signaling (IIS). pRJ-Fr. 5 induced changes in the expression of 3 genes encoding insulin-like peptides. Moreover, pRJ-Fr. 5 and reduced IIS shared some common features in terms of their effect on gene expression, such as up-regulation of dod-3 and down-regulation of dod-19, dao-4 and fkb-4. The dod-19 is a previously identified life span determinant in C. elegans, and the fkb-4 encodes a homologue of the mammalian FK506-binding protein. 10-Hydroxy-2-decenoic acid (10-HDA), which was present in high concentration in pRJ-Fr. 5, increased the lifespan independently of DAF-16 activity.These results demonstrate that RJ and its related substances extended the life span in C. elegans, suggesting that RJ may contain longevity-promoting factors common to diverse species across phyla. pRJ-Fr. 5 had higher life span-extending activity than either RJ or pRJ and extended the life span in part through the IIS-DAF-16 pathway. We provide the first evidence that 10-HDA, a defined natural product in RJ, extended organismal lifespan. It is noteworthy that 10-HDA performed its lifespan-extending function through a mechanism totally different from the IIS-DAF-16 pathway. Further search and characterization of the lifespan-extending agents in RJ and pRJ may broaden our understanding of the gene network of longevity regulation in diverse species and provide the possibility for nutraceutical interventions in the aging process. C. elegans N2 hermaphrodites were untreated or treated with pRJ-Fr. 5 (25mg/ml) for 24 h starting at the larval 4 (L4) stage.

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Mutations Increasing Drosophila melanogaster Life Span

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