Endogenous Substrates of Dormant, Activated and Germinating Ascospores of Neurospora Tetrasperma.

Abstract

Ascospores of N. tetrasperma contain about 25% total lipids and 33% carbohydrates on a dry weight basis. The lipids serve as the source of energy for dormant ascospores which have enough of this substrate to survive for 18 years when stored at 4[degree]C, or for less than 1 year when shaken in water at room temperature. On the other hand, carbohydrates do not appear to be utilized during dormancy but begin to disappear almost immediately after the spores are heat-activated. Fats are utilized during this time as well, but in lesser amounts than carbohydrates. Only those carbohydrates soluble in hot 80% ethanol are affected in this way, for the acid-soluble fraction remains almost constant in amount after a small initial decrease upon activation. Reducing sugars and glucose comprise less than 1% of the ethanol-soluble carbohydrates, while esters and steroids are the major constituents of the lipids. A comparison is made between conidia and ascospores of Neurospora on the basis of their content of lipids and carbohydrates.