Induction of Meiosis and Sporulation in Differently Aged Cells of Saccharomyces Cerevisiae

Abstract

It has been known that age 0 cells of Saccharonayces cerevisiae, lacking any bud scar, hardly form any spore, while the cells of age 1 or more sporulate abundantly.Based on this finding we attempted to elucidate at what stage of cell age the age 0 cells acquire sporulation activity. Aliquots of the synchronous culture started from small age 0 cells were transferred to sporulation media at time intervals and sporulation in each culture was examined.Results showed that age 0 cells were endowed with the sporulating ability just before the first bud initiation.The sporulation ability decreased after the first budding and increased again at the stage of the second budding. The fluorescent staining of the resultant asci revealed that most asci derived from cultures just before the initiation of the first budding carried neither bud nor bud scar. It was also observed that the number of spores per ascus changed with the cellular age. Cells in synchronous culture of large cells, most of which bear more than one bud scar showed similar changes in the sporulating ability during their cell cycle. Addition of tomato juice to the culture media preceding sporulation stimulated the sporulating ability.

Conversion of Mitotic to Meiotic Cells in Saccharomyces cerevisiae. I. Efficient Induction of Meiosis

“…Numerous observations on the ability to sporulate have shown a sharp difference between parent and newborn daughter cells, and various reasons have been given for the low ability in young cells. The behavior of HU-and non-treated cells reported here, is inconsistent with the views that the phase of the cell cycle (5,15) or cell age with respect to the number of bud scars (20) has a direct relation on the induction of sporulation. This implies that, at least, the ability for meiosis involves cell size when sporulation is induced.…”

“…The factor most prominently cited for the insufficiency ofthe sporulation process is the low ability of newborn daughter cells or buds to form spores in spite of a very high capability in parent cells (5,15,18,20). In a previous paper (19), we described the proliferation of yeast cells in the presence of hydroxyurea (HU) and the simultaneous budding of overgrown parent and daughter cells.…”

Increase in Cell Size as a Measure of Growth of Saccharomyces Cerevisiae

“…The sporulating activity was extremely low in the age 0 cells (26,27). The budding initiation of new-born daughter cells was some time behind the next budding of their mother cells without exception (16,17).…”

Aging and senescence of the budding yeast Saccharomyces cerevisiae

“…It does not appear to be related to the ability to secrete and respond to pheromones. In contrast, the abitity to sporutate appears to increase after a cell divides for the first time (Sando et ai. 1973).…”