Differential Expression upon infection with Salmonella typhimurium (t3)

Dictyostelium discoideum is a professional phagocyte and it uses phagocytosis as a way to get food. However, there are a number of bacteria that subvert this professional phagocyte. In this study we investigated whether Salmonella typhimurium is also pathogenic for D. discoideum. AX2 cells were grown in a 1000-fold excess of E.Coli B/r in Soerensen phosphate buffer under shaking. Cell were washed and resuspended at a concentration of 2 x 10^6 per ml with a 1000-fold excess of either S. typhimurium or E.Coli B/r in Soerensen phosphate buffer. After 0, 1, 2 and 3 hours cells were washed free of bacteria and total RNA was extracted for DNA microarray analysis. For each timepoint three samples were taken and the experiment was done twice so that we had six samples for each timepoint (e.g. S1, S2, S3 and S1', S2', S3' ).