scholarly journals Inositol transport in Saccharomyces cerevisiae is regulated by transcriptional and degradative endocytic mechanisms during the growth cycle that are distinct from inositol-induced regulation.

1996 ◽  
Vol 7 (1) ◽  
pp. 81-89 ◽  
Author(s):  
K S Robinson ◽  
K Lai ◽  
T A Cannon ◽  
P McGraw

Regulation of inositol uptake activity in Saccharomyces cerevisiae during the growth cycle was examined. Activity increased as the cell population transited from lag phase to exponential growth, and continued to increase until late exponential phase. The increase in activity was due to increased transcription of the ITR1 gene and synthesis of the Itr1 permease. When the culture reached stationary phase, uptake activity decreased and dropped to a minimum within 4 h. The decrease was due to repression of ITR1 transcription, independent of the negative regulator Opi1p, and degradation of the existing permease. Degradation depended on delivery of the permease to the vacuole through the END3/END4 endocytic pathway. During exponential growth in inositol-containing medium the permease is also rapidly degraded, whereas in inositol-free medium the permease is highly stable. Rapid degradation of the permease at stationary phase occurred in inositol-free medium, indicating that there are two distinct mechanisms that trigger endocytosis and degradation in response to different physiological stimuli. In addition, the level of the enzyme required for inositol biosynthesis, inositol-1-phosphate synthase, encoded by INO1, is not reduced in stationary-phase cells, and this contrast in the regulation of inositol supply is discussed.

Author(s):  
Pryce L. Haddix

ABSTRACT Serratia marcescens is a prolific producer of the red, membrane-associated pigment prodigiosin. Earlier work has established both a positive role for prodigiosin in ATP production during population lag phase and a negative role during high-rate, low cell density growth. This study uses the growth rate and growth phase modulation afforded by chemostat culture to extend prodigiosin functional analysis to the high density and stationary phases. Cellular levels of prodigiosin were positively associated with cellular levels of ATP during high-density growth, and artificial pigment induction during this phase increased cellular ATP. Following peak high density ATP per cell, early stationary phase enabled significant population growth while prodigiosin levels remained high and ATP declined. During late stationary phase, ATP per cell was positively associated with prodigiosin per cell while both declined during continued growth. These results provide correlational evidence for multiple effects of prodigiosin pigment on ATP production throughout the growth cycle. Earlier work and the data presented here enable formulation of a working model for the oscillating relationships between cellular levels of ATP and prodigiosin during batch culture.


1962 ◽  
Vol 8 (5) ◽  
pp. 655-661 ◽  
Author(s):  
I. L. Stevenson

Changes in macromolecular levels (RNA, DNA, protein) have been followed during the growth cycle of A. globiformis. When a stationary phase culture is transferred to fresh medium a 12-fold increase in RNA level and 6-fold increases in DNA and protein levels are observed during the predivisional lag phase. Initially RNA synthesis precedes DNA and protein synthesis but all reach the same differential rate 2 to 3 hours prior to division. During the predivisional lag period the RNA/protein ratio per cell expands from 0.19 to 0.36. Once division occurs, cells of A. globiformis remain in the enlarged pleomorphic form until the medium becomes limiting; at this time synthesis of macromolecules ceases and the continued division (three to four generations) results in progressively smaller cells until the coccoid stationary phase cell-type is reached.


1975 ◽  
Vol 148 (2) ◽  
pp. 253-258 ◽  
Author(s):  
J A Hackett ◽  
P J Brennan

Besides the monomannophosphoinositide previously reported in Corynebacterium aquaticum small amounts of other, apparently more glycosylated, mannophosphoinositides have been identified in stationary phase cells. Moreover, by labelling cells with [32P]Pi, phosphatidylinositol was found, comprising about 1.5% of the stationary-phase phospholipids. 2. Pulse-chase experiments performed on cells in the late exponential phase of growth further suggested the sequence phosphatidylinositol leads to monomannophosphoinositide as the first step in the biosynthesis of the mannophosphoinositides. 3. Di-and tri-mannophosphoinositides are apparently the main mannophosphoinositides present during exponential growth. Monomannophosphoinositide predominates only in late stationary phase; in the earlier stationary phase, phosphatidylinositol comprises 50% of the phosphoinositide lipid, and tetramannophosphoinositide constitutes much of the remainder. 4. The metabolism and functions of the mannophosphoinositides are discussed, particularly in relation to changes in their composition throughout the growth cycle.


2008 ◽  
Vol 71 (7) ◽  
pp. 1412-1421 ◽  
Author(s):  
J. BAUTISTA-GALLEGO ◽  
F. N. ARROYO-LÓPEZ ◽  
M. C. DURÁN-QUINTANA ◽  
A. GARRIDO-FERNÁNDEZ

A quantitative investigation on the individual effects of sodium (NaCl), potassium (KCl), calcium (CaCl2), and magnesium (MgCl2) chloride salts against Lactobacillus pentosus and Saccharomyces cerevisiae, two representative microorganisms of table olives and other fermented vegetables, was carried out. In order to assess their potential activities, both the kinetic growth parameters and dose-response profiles in synthetic media (deMan Rogosa Sharpe broth medium and yeast-malt-peptone-glucose broth medium, respectively) were obtained and analyzed. Microbial growth was monitored via optical density measurements as a function of contact time in the presence of progressive chloride salt concentrations. Relative maximum specific growth rate and lag-phase period were modeled as a function of the chloride salt concentrations. Moreover, for each salt and micro-organism tested, the noninhibitory concentrations and the MICs were estimated and compared. All chloride salts exerted a significant antimicrobial effect on the growth cycle; particularly, CaCl2 showed a similar effect to NaCl, while KCl and MgCl2 were progressively less inhibitory. Microbial susceptibility and resistance were found to be nonlinearly dose related.


1987 ◽  
Vol 7 (4) ◽  
pp. 1338-1345 ◽  
Author(s):  
S P Johnson ◽  
J R Warner

The phosphorylation of mammalian ribosomal protein S6 is affected by a variety of agents, including growth factors and tumor promoters, as well as by expressed oncogenes. Its potential role in the regulation of protein synthesis has been the object of much study. We have developed strains of Saccharomyces cerevisiae in which the phosphorylatable serines of the equivalent ribosomal protein (S10) were converted to alanines by site-directed mutagenesis. The S10 of such cells is not phosphorylated. Comparison of these cells with the parental cells, whose genomes differ by only six nucleotides, revealed no differences in the lag phase or logarithmic phase of a growth cycle, in growth on different carbon sources, in sporulation, or in sensitivity to heat shock. We conclude that in S. cerevisiae the phosphorylation of ribosomal protein S10 may play no role in regulating the synthesis of proteins. This conclusion leads one to ask whether certain protein phosphorylations are simply the adventitious, if easily observable, result of the imperfect specificity of one or another protein kinase.


2008 ◽  
Vol 71 (9) ◽  
pp. 1915-1918 ◽  
Author(s):  
ANTONIO J. DE JESÚS ◽  
RICHARD C. WHITING

In previous studies, the growth of L. monocytogenes has been modeled under different CO2 headspace concentrations; however, the inoculum cells were always in the stationary phase. In this study, the growth of L. monocytogenes under different CO2 concentrations as affected by the physiological state of the cells was investigated. Exponential-growth-phase, stationary-phase, dried, and starved cells were prepared and inoculated at 5°C into brain heart infusion broths that had been preequilibrated under atmospheres of 0, 20, 40, 60, or 80% CO2 (the balance was N2). Lag-phase duration times (LDTs) and exponential growth rates were determined by enumerating cells at appropriate time intervals and by fitting the data to a three-phase linear function that has a lag period before the initiation of exponential growth. Longer LDTs were observed as the CO2 concentration increased, with no growth observed at 80% CO2. For example, the LDTs for exponential-phase, stationary-phase, starved, and dried cells were 2.21, 8.27, 9.17, and 9.67 days, respectively, under the 40% CO2 atmosphere. In general, exponential-growth-phase cells had the shortest LDT followed by starved cells and stationary-phase cells. Dried cells had the longest LDT. Exponential growth rates decreased as the CO2 concentrations increased. Once exponential growth was attained, no retained differences among the various initial physiological states of the cells for any of the atmospheres were observed in the exponential growth rates. The exponential growth rates under 0, 20, 40, 60, and 80% CO2 averaged 0.39, 0.37, 0.23, 0.23, and 0.0 log CFU/day, respectively. Dimensionless factors were calculated that describe the inhibitory action of CO2 on the LDTs and exponential growth rates for the various physiological states.


Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 684-689 ◽  
Author(s):  
Margaret Werner-Washburne ◽  
Elizabeth A. Craig

The hsp70 multigene family of Saccharomyces cerevisiae is a complex multigene family, composed of members exhibiting complex patterns of regulation. Expression of some members is induced after a heat shock, whereas expression of others is repressed. Some members of the family are expressed during exponential growth. One gene, SSA3, shows an unusual pattern of expression during approach to stationary phase. While most RNAs decrease in abundance, SSA3 RNA levels dramatically increase. The constitutive expression of SSA3 in cells lacking adenylate cyclase activity suggests that cAMP modulates SSA3 expression.Key words: heat shock proteins, S. cerevisiae, cAMP, gene expression, stress seventy genes.


1987 ◽  
Vol 7 (4) ◽  
pp. 1338-1345 ◽  
Author(s):  
S P Johnson ◽  
J R Warner

The phosphorylation of mammalian ribosomal protein S6 is affected by a variety of agents, including growth factors and tumor promoters, as well as by expressed oncogenes. Its potential role in the regulation of protein synthesis has been the object of much study. We have developed strains of Saccharomyces cerevisiae in which the phosphorylatable serines of the equivalent ribosomal protein (S10) were converted to alanines by site-directed mutagenesis. The S10 of such cells is not phosphorylated. Comparison of these cells with the parental cells, whose genomes differ by only six nucleotides, revealed no differences in the lag phase or logarithmic phase of a growth cycle, in growth on different carbon sources, in sporulation, or in sensitivity to heat shock. We conclude that in S. cerevisiae the phosphorylation of ribosomal protein S10 may play no role in regulating the synthesis of proteins. This conclusion leads one to ask whether certain protein phosphorylations are simply the adventitious, if easily observable, result of the imperfect specificity of one or another protein kinase.


2004 ◽  
Vol 186 (21) ◽  
pp. 7344-7352 ◽  
Author(s):  
Sherry A. Coleman ◽  
Elizabeth R. Fischer ◽  
Dale Howe ◽  
David J. Mead ◽  
Robert A. Heinzen

ABSTRACT Coxiella burnetii undergoes a poorly defined developmental cycle that generates morphologically distinct small-cell variants (SCV) and large-cell variants (LCV). We developed a model to study C. burnetii morphogenesis that uses Vero cells synchronously infected with homogeneous SCV (Nine Mile strain in phase II) harvested from aged infected cell cultures. A time course transmission electron microscopic analysis over 8 days of intracellular growth was evaluated in conjunction with one-step growth curves to correlate morphological differentiations with growth cycle phase. Lag phase occurred during the first 2 days postinfection (p.i.) and was primarily composed of SCV-to-LCV morphogenesis. LCV forms predominated over the next 4 days, during which exponential growth was observed. Calculated generation times during exponential phase were 10.2 h (by quantitative PCR assay) and 11.7 h (by replating fluorescent focus-forming unit assay). Stationary phase began at approximately 6 days p.i. and coincided with the reappearance of SCV, which increased in number at 8 days p.i. Quantitative reverse transcriptase-PCR demonstrated maximal expression of scvA, which encodes an SCV-specific protein, at 8 days p.i., while immunogold transmission electron microscopy revealed degradation of ScvA throughout lag and exponential phases, with increased expression observed at the onset of stationary phase. Collectively, these results indicate that the overall growth cycle of C. burnetii is characteristic of a closed bacterial system and that the replicative form of the organism is the LCV. The experimental model described in this report will allow a global transcriptome and proteome analysis of C. burnetii developmental forms.


Sign in / Sign up

Export Citation Format

Share Document