THE EFFECT OF FURFURAL UPON THE GERMINATION AND RESPIRATION OF ASCOSPORES OF NEUROSPORA TETRASPERMA

Abstract

THE WORK of Emerson (1948) showed for the first time that chemical treatment, as well as the application of heat (Goddard 1935, 1939), could activate ascospores of Neurospora. She reported that furfural and furfuryl alcohol in very low concentrations effectively induced germination, but the mechanism of this activating effect was not investigated. Since that time, Sussman (1953) has reported that 11 other heterocyclics also serve as activators of ascospores. The purpose of the following experiments was to follow up these observations with an investigation of the metabolic effects of chemical activators. MATERIALS AND METHODS.-Ascospores were obtained by crossing strains 374 and 377 of Neurospora tetrasperma which were then grown as outlined by Goddard (1935). Since Emerson (personal communication, 1951) has shown that ascospores rapidly lose their sensitivity to chemical activators, these were used within a month after harvesting (fresh spores). In the experiments wherein the ageing effect or loss of sensitivity was studied, old spores were used: these had been harvested at least 6 mo. before use. Both fresh and old ascospores were stored at 40 C. at 65 per cent relative humidity. Respiratory measurements were made in Warburg vessels of 7 ml. capacity with a fluid volume of 1.1 ml. Standard Warburg manometers were used at a shaking rate of 120 oscillations per minute, while the temperature of the bath was maintained at, 260 C. except when otherwise stated. Anaerobic conditions were obtained by flushing the vessels with nitrogen which had been passed through alkaline pyrogallol and then over a heated copper coil to remove contaminant CO2 and 02. Spore suspensions for the respirometric determinations were made up by determining the volume of a weighed sample of spores after centrifuging in a hematocrit tube. The spores were then washed with a 1:4 dilution of sodium hypochlorite (Fishers reagent grade) to kill contaminant conidia, rinsed several times in distilled water, and finally resuspended in 30 parts of distilled water (by volume). Controls of dormant spores suspended in water were always run. The rate of oxygen uptake remained constant; therefore, it was assumed that contamination was controlled effectively. Spores were heat activated by suspending them in distilled water at 600 C. for 30 min. in a constant temperature oil bath. Chemical activation was usu-