The Reversible Heat Activation of Respiration in Neurospora

Warburg (9) and Runnstrom (6) have shown that a large increase in respiratory rate occurs upon fertilization of sea urchin eggs, and Bodine (2) has shown that the respiration of diapause grasshopper embryos is low and that a marked increase in respiratory rate occurs when diapause is broken. A comparable case has been discovered in the ascospores of the fungus Neurospora tetra-sperma. Neurospora produces two types of spores, conidia and ascorspores. Shear and Dodge (7) showed that the conidia germinate readily upon transfer to culture solutions but that the ascospores are dormant, and that these dormant spores may be induced to germinate by a short period of heat treatment. Goddard (3) and Goddard and Smith (4) have shown that the activation of the dormant spores is reversible, and that following activation there is a large increase in respiratory rate and initiation of fermentation.