The anti-wasp immune response across the genus Drosophila. 公开

Abstract

Abstract
The anti-wasp immune response across the genus Drosophila.
One of the most common parasites of Drosophila in nature are parasitic wasps, which lay
their eggs in Drosophila larvae and pupae. Drosophila melanogaster mounts an immune
response against wasp eggs and larvae termed melanotic encapsulation, whereby hemocytes
form a multi-cellular, multi-layered capsule around the intruder, turning it black with
melanin. We were interested in whether this melanotic encapsulation response is conserved
across the genus Drosophila. Thus, we assayed fly immune mechanisms and immune success
in a panel of 26 Drosophila species using a diversity of parasitic wasp species . We found
that different Drosophila species have unique hemocyte types not found in D. melanogaster,
and that certain unique hemocyte lineages are involved in wasp egg encapsulation.
Additionally, we took an in depth look at D. melanogaster, due to its poor performance against
the wasp panel. Given that larvae of the fruitfly Drosophila melanogaster consume yeasts
growing on rotting fruit and have evolved resistance to yeast fermentation products such as
ethanol, we decided to test whether ethanol protects fruitflies from parasitoids. Here, we
show that exposure to ethanol reduces wasp oviposition into fruitfly larvae. Furthermore, if
infected, ethanol consumption by fruitfly larvae causes increased death of wasp larvae
growing in the hemocoel and increased fly survival without need of the stereotypical anti-
wasp immune response. This multi-faceted protection afforded to fly larvae by ethanol is
significantly more effective against a generalist wasp than a wasp that specializes on D.
melanogaster. We found that fly larvae seek out ethanol-containing food when
infected, indicating they use alcohol as an anti-wasp medicine . We also examined D. suzukii
and found that D. suzukii constitutively produces up to five times more hemocytes than D.
melanogaster. Using a panel of 24 parasitoid wasp strains representing fifteen species, four
families, and multiple virulence strategies, we found that D. suzukii was significantly more
resistant to wasp parasitism than D. melanogaster. Thus, our data suggest that the
relationship between hemocyte production and wasp resistance is general. Finally, we
examined Z. indianus and found a novel hemocyte type to be involved in encapsulation ability.

Table of Contents

Table of Contents
INTRODUCTION ................................................................................................................... 8
CHAPTER 1: THE ANTI-WASP IMMUNE RESPONSE ACROSS THE GENUS
DROSOPHILA. .......................................................................................................................10
CHAPTER 2: ALCOHOL CONSUMPTION AS SELF-MEDICATION AGAINST
BLOOD-BORNE PARASITES ............................................................................................. 47
CHAPTER 3: HIGH HEMOCYTE LOAD IS ASSOCIATED WITH INCREASED
RESISTANCE AGAINST PARASITOIDS IN DROSOPHILA SUZUKII, A RELATIVE
OF D. MELANOGASTER
.................................................................................................................................................. 68
CHAPTER 4: ZAPRIONUS INDIANUS: A NOVEL FORM OF CELLULAR
ENCAPSULATION ...............................................................................................................107

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CONCLUSION .....................................................................................................................132
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FIGURES ...............................................................................................................................135
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About this Master's Thesis

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School	Laney Graduate School
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Biology, Ecology Biology, General
关键词	immunity evolution host drosophila parasite phylogeny
Committee Chair / Thesis Advisor	Schlenke, Todd, Emory University
Committee Members	Moberg, Kenneth H, Emory University De Roode, Jacobus, Emory University

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