Biological Sciences, School of


Date of this Version

Spring 4-21-2014

Document Type



Zhen Hu. 2014. Stress Responses and Energy Storage in Drosophila melanogaster Selected for Resistance to a Gram-Positive Bacillus cereus Spores. MS thesis, University of Nebraska-Lincoln.


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 Harshman. Lincoln, Nebraska: April, 2014

Copyright (c) 2014 Zhen Hu


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