Stress- and immune defence in Drosophila melanogaster

Abstract: Many cellular responses are regulated at the transcriptional level. Newly synthesized proteins and peptides rapidly exert their function at the time of expression, as a response to different environmental cues. In an attempt to analyze transcriptional activation in response to bacteria, we have identified a novel family of eight stress-induced humoral factors, the Turandot proteins. All Turandot (Tot) genes are induced under stressful conditions such as bacterial infection, heat shock, UV-irradiation and oxidizing agents. One of the members, TotA, is shown to promote increased resistance to the lethal effects of high temperature, indicating that this protein family plays an important role for a systemic stress adaptation.This thesis also describes some novel aspects of the Drosophila immune response. Flies mutant for the transcriptional activator, and NF-kB homolog, Relish will not survive a bacterial or fungal infection. Transcriptional characterization shows that the synthesis of antibacterial effector molecules is almost eliminated in these flies. This establishes Relish as the main transcriptional activator for defence against Gram-negative bacteria and fungi.I also present novel findings about the antifungal properties of the immune peptide Cecropin A.