The effect of artificial selection for extended life span and late age fecundity on the age-specific phagocytic ability of blood cells in adult Drosophila melanogaster

Title	The effect of artificial selection for extended life span and late age fecundity on the age-specific phagocytic ability of blood cells in adult Drosophila melanogaster
Author	Ji, Zhejun
Advisors	Leips, Jeff ;
Program	Biological Sciences
UMBC Department	Biological Sciences
Document Type	thesis
Sponsors	University of Maryland, Baltimore County (UMBC)
Keywords	aging; Drosophila; engulfment; immunosenescence; innate immunity; phagocytosis
Date Issued	2012-01-01
Abstract	Immunosenescence is defined as the functional decline of the immune response with age and is found in most organisms. In mammals both the innate and adaptive components of the immune response decline with age, however, the cellular and genetic mechanisms of this phenomenon still remain unclear. Here, I use Drosophila melanogaster as our model to study the general effect of age on innate immunity. I studied the effect of age on phagocytic ability in six distinct <italic>Drosophila</italic> populations: three populations that had been artificially selected for extended life span and three unselected control populations. I measured phagocytic ability by injecting fluorescently-labeled heat killed <italic>E. coli</italic> into flies at different ages and counted the number of <italic>E. coli</italic> engulfed by the blood cells around the heart. Interestingly, I found that the average number of <italic>E. coli</italic> that were engulfed by blood cells increased with age in all six fly populations. While there was no difference between the Selected and Control flies when data were combined across ages, I did find that the effect of age on phagocytic ability differed between the Control and Selected populations. The Control populations had a relatively larger number of engulfed bacteria at early age while populations selected for longer life span and increased late age fecundity had a higher engulfment at older age. To further test the efficiency of the phagocytic ability, I independently injected four of the populations with latex beads, which cannot be digested after engulfment by the blood cells. I found variable results with the beads but in general they were consistent with the bacteria data. In conclusion, our data indicates that life span extension is genetically correlated with phagocytosis ability and exhibits a trade-off with early age phagocytic efficiency. Understanding the genetic basis of this trade-off is an important topic for future study.
Identifier	10643
Format	application:pdf
Language	en
Collection	UMBC Thesis and Dissertations.
Rights Statement	This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll@umbc.edu.
Source	Ji_umbc_0434M_10643.pdf

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The effect of artificial selection for extended life span and late age fecundity on the age-specific phagocytic ability of blood cells in adult Drosophila melanogaster

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