Catalase activity is necessary for heat-shock recovery in Aspergillus nidulans germlings

To understand the molecular mechanisms induced by stress that contribute to the development of tolerance in eukaryotic cells, the filamentous fungus A spergillus nidulans has been chosen as a model system. Here, the response o f A. nidulans germlings to heat shock is reported. The heat treatment drama tically increased the concentration of trehalose and induced the accumulati on of mannitol and mRNA from the catalase gene catA. Both mannitol and cata lase function to protect cells from different reactive oxygen species. Trea tment with hydrogen peroxide increased A. nidulans germling viability after heat shock whilst mutants deficient in catalase were more sensitive to a 5 0 degrees C heat exposure. It is concluded that the defence against the let hal effects of heat exposure can be correlated with the activity of the def ence system against oxidative stress.