Control by Nutrients of Growth and Cell Cycle Progression in Budding Yeast, Analyzed by Double-Tag Flow Cytometry

Abstract

To gain insight on the interrelationships of the cellular environment, the properties of growth, and cell cycle progression, we analyzed the dynamic reactions of individual Saccharomyces cerevisiae cells to changes and manipulations of their surroundings. We used a new flow cytometric approach which allows, in asynchronous growing S. cerevisiae populations, tagging of both the cell age and the cell protein content of cells belonging to the different cell cycle set points. Since the cell protein content is a good estimation of the cell size, it is possible to follow the kinetics of the cell size increase during cell cycle progression. The analysis of the findings obtained indicates that both during a nutritional shift-up (from ethanol to glucose) and following the addition of cyclic AMP (cAMP), two important delays are induced. The preexisting cells that at the moment of the nutritional shift-up were cycling before the Start phase delay their entrance into S phase, while cells that were cycling after Start are delayed in their exit from the cycle. The combined effects of the two delays allow the cellular population that preexisted the shift-up to quickly adjust to the new growth condition. The effects of a nutritional shift-down were also determined.

Roles of SWI/SNF and HATs throughout the dynamic transcription of a yeast glucose-repressible gene

“…To probe the more general cellular response to acute glucose limitation, we determined the fraction of unbudded cells (cells in G1) in a time course following the carbon source shift. The transition from G1 to S phase is tightly controlled by the availability of carbon source, and glucose deprivation causes G1 arrest (Alberghina et al, 1998;Newcomb et al, 2003). Remarkably, the pattern of cells in G1 following the carbon source shift was also biphasic ( Figure 1C).…”

“…Why is the transcriptional induction biphasic? We suggest that the initial stress response triggers a transient repression of energy-consuming processes such as translation, transcription, and cell cycle progression (Martinez-Pastor and Estruch, 1996;Alberghina et al, 1998;Ashe et al, 2000;Gasch et al, 2000;Causton et al, 2001;Newcomb et al, 2003) (Figure 1C). As a result, the cell compensates for the sudden shortage of energy or other nutrients and quickly restores the balance between energy production and consumption.…”

Glucose‐dependent cell size is regulated by a G protein‐coupled receptor system in yeast Saccharomyces cerevisiae

“…In S. cerevisiae, when glucose is added to cells growing in a poor carbon source, the critical cell size required for cell division is quickly reset from small to large (Alberghina et al 1998). Then, we tested using a synchronized popu-lation of G1 cells if GPR1 and GPA2 are required for a rapid response to glucose addition.…”

Flow cytometric investigation of heterogeneous copper-sensitivity in asynchronously grown Saccharomyces cerevisiae

“…Cells at 90^100% of the maximum cell volume (R11) consisted almost exclusively of 2C DNA (12% had a 1C DNA content) and thus most likely corresponded to cells about to undergo mitosis. As budding yeast divides asymmetrically, cells of the same size are not expected to be strictly of the same cell cycle stage [14]. This may account for the simultaneous presence of 1C and 2C cells in many fractions.…”

“…Yeast cell cycle studies are usually carried out using synchronous cultures or on a relatively small number of cells, by time-lapse studies [13]. Flow cytometry can be used to circumvent cell synchronization for certain applications and is becoming an increasingly popular method for cell cycle analysis [14,15]. The novel £ow cytometric approach we adopted here enabled us to demonstrate that di¡erential copper-sensitivity is associated with partition in di¡erent cell cycle stages in S. cerevisiae.…”