1 research outputs found
Apoptosis at Inflection Point in Liquid Culture of Budding Yeasts
Budding yeasts are highly suitable for aging studies, because the number of bud
scars (stage) proportionally correlates with age. Its maximum stages are known
to reach at 20–30 stages on an isolated agar medium. However, their stage
dynamics in a liquid culture is virtually unknown. We investigate the population
dynamics by counting scars in each cell. Here one cell division produces one new
cell and one bud scar. This simple rule leads to a conservation law: “The
total number of bud scars is equal to the total number of cells.” We find
a large discrepancy: extremely fewer cells with over 5 scars than expected.
Almost all cells with 6 or more scars disappear within a short period of time in
the late log phase (corresponds to the inflection point). This discrepancy is
confirmed directly by the microscopic observations of broken cells. This finding
implies apoptosis in older cells (6 scars or more)