Differential Responses to Environmental Conditions by Fungal Cells Sensitized by Heat Shock or UV Irradiation

Cells of the ascomycele Ophiostoma multianulatum were sensitized to the supra-optimal temperature of 30°C either by heat shock or by UV irradiation. At this incubation temperature the death rate of the heat-shocked cells was higher than that of the irradiated cells. This difference was increased if hydrolysed casein was added to the incubation medium. The heat-shocked cells were also killed faster at 30°C, if nitrogen instead of air was bubbled through the cell suspension. Heat shock, in contrast to UV irradiation, strongly increased the sensitivity to a high concentration of sodium chloride.