My project has two main goals: 1) to determine if Drosophila melanogaster exhibits immunosenesence, 2) to determine if this difference in immune response has a genetic basis on the second chromosome.

To achieve the first goal, I have selected 30 of our Chromosome II substitution lines. Their ages are standardized by allowing the parental generation to lay eggs for 48 hours. The homozygous female virgins are collected and half are raised for 1 week, the other half raised for 4 weeks. The flies are then injected with a solution of a streptomycin resistant strain of E. coli, and allowed to mount an immune response for 24 hours. Next, the flies are homogenized and plated. The plates incubate overnight and the colonies are counted and recorded. Several controls are also done along the way.

I am looking for differences among these 30 lines as well as differences between the two ages. Promising preliminary data on 9 lines of flies indicate differences, but also exhibit huge variability.

To achieve the second goal, we are collaborating with Kim Hughes lab in Illinois. Together we will use microarrays to look at expression in two of the lines and at both ages. The two lines will be chosen from the data generated by the injection assay. We will use one line that exhibits a strong immune response and one that shows a weak response. E. coli is gram negative, which will trigger the Imd pathway to mount an immune response. Several of the genes known to be involved in the Imd pathway are located along the second chromosome.