A humoral stress response in Drosophila

The ability to react to unfavorable environmental changes is crucial for su rvival and reproduction, and several adaptive responses to stress have been conserved during evolution [1-3], Specific immune and heat shock responses mediate the elimination of invading pathogens and of damaged proteins or c ells [4-6], Furthermore, MAP kinases and other signaling factors mediate ce llular responses to a very broad range of environmental insults [7-9], Here we describe a novel systemic response to stress in Drosophila, The Turando t A (TotA) gene encodes a humoral factor, which is secreted from the fatbod y and accumulates in the body fluids. TotA is strongly induced upon bacteri al challenge, as well as by other types of stress such as high temperature, mechanical pressure, dehydration, UV irradiation, and oxidative agents. It is also upregulated during metamorphosis and at high age. Strikingly, flie s that overexpress TotA show prolonged survival and retain normal activity at otherwise lethal temperatures. Although TotA is only induced by severe s tress, it responds to a much wider range of stimuli than heat shock genes s uch as hsp70 or immune genes such as Cecropin A1.