THE METABOLISM OF YEAST SPORULATION: IV. CYTOLOGICAL AND PHYSIOLOGICAL CHANGES IN SPORULATING CELLS
Parallel observations were made of respiratory activity, content of glycogen and fat, and appearance of the nucleus, during transition of cells of Saccharomyces cerevisiae from the vegetative to the sporulated state. With acetate as the carbon source in sporulation medium, the endogenous respiratory ability of the cells first increased (after about 10 hours) and finally declined. Ability to respire glucose remained high during sporogenesis but diminished somewhat by 42–43 hours, at which time most of the cells contained spores. Glycogen and fat increased in amount during the early stages of sporogenesis but appeared to diminish during formation of spore walls. In vegetative and reductional nuclear division the nuclear material appeared organized into rod-like structures, some regions of which stained more densely. Classical cytological configurations were not observed. With dihydroxyacetone as the carbon source in sporulation medium the sequence of events was similar, but required about twice as much time, possibly owing to the slower respiration of this substance.