Stress Responses and Energy Storage in Drosophila melanogaster Selected for Resistance to a Gram-positive Bacillus cereus Spores

Authors

• Zhen Hu, University of Nebraska-LincolnFollow

First Advisor

Lawrence G. Harshman

Date of this Version

4-2014

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Biological Sciences

Under the supervision of Professor Lawrence G. Harshman

Lincoln, Nebraska, April 2014

Comments

Copyright 2014, Zhen Hu. Used by permission

Abstract

A survival response study was carried out by using D. melanogaster and the opportunistic pathogen B. cereus as the agent of selection. The spores of B. cereus, a gram-positive bacteria that can cause the human pathogen disease, were applied in our artificial laboratory selection. Selected lines were treated with B. cereus spores. Wound control lines were punctured with a needle dipped into sterile H₂O. Control lines did not apply any treatment. Three different environmental treatments were used within each line type (autoclaved spores of B.cereus, sterile H₂O and no treatment). The autoclaved spores were used as an inducer of the immune response in our study, with the purpose of boosting their innate immunity. Our hypothesis was that selected lines will live longer as they are immune to “B. cereus” spores. By comparing the average mortality rate of different line types, flies in selected lines were observed to die slowest, which was correspondent to our hypothesis. Selected and control lines were studied in different stress environment (starvation, desiccation, chill coma, oxidation) to investigate their survival response to stress. Those flies resistant to B. cereus spores in our selection were expected to survive longer than the flies in other line type under different stresses. To study the trade-off for these survival responses, energy components were measured. The result showed that there was a change in lipid and glycogen concentration in selected flies, which confirmed our trade-off hypothesis between survival responses and energy component.

Advisor: Lawrence G. Harshman