scholarly journals Macromolecular crowding limits growth under pressure

2021 ◽  
Author(s):  
Baptiste Alric ◽  
Cécile Formosa-Dague ◽  
Etienne Dague ◽  
Liam J Holt ◽  
Morgan Delarue
Keyword(s):  
Cell Growth ◽  
Macromolecular Crowding ◽  
Physical Property ◽  
Signaling Cascades ◽  
Yeast Saccharomyces Cerevisiae ◽  
Molecular Sensors ◽  
Confined Spaces ◽  
Microbial Infections ◽  
Domains Of Life ◽  
Fundamental Physical

Cells that grow in confined spaces eventually build up mechanical compressive stress. This growth-induced pressure (GIP) decreases cell growth. GIP is important in a multitude of contexts from cancer, to microbial infections, to biofouling, yet our understanding of its origin and molecular consequences remains limited. Here, we combine microfluidic confinement of the yeast Saccharomyces cerevisiae, with rheological measurements using genetically encoded multimeric nanoparticles (GEMs) to reveal that growth-induced pressure is accompanied with an increase in a key cellular physical property: macromolecular crowding. We develop a fully calibrated model that predicts how increased macromolecular crowding hinders protein expression and thus diminishes cell growth. This model is sufficient to explain the coupling of growth rate to pressure without the need for specific molecular sensors or signaling cascades. As molecular crowding is similar across all domains of life, this could be a deeply conserved mechanism of biomechanical feedback that allows environmental sensing originating from the fundamental physical properties of cells.

scholarly journals Application Of The Z And Laplace Transforms To Panification Yeast Production Using An Airlift Bioreactor

2020 ◽  
Author(s):  
Arnaldo Silva Oliveira ◽  
Juan C. B. Neto ◽  
Igor J. B. Santos ◽  
Edson R. Nucci
Keyword(s):  
Cell Growth ◽  
Product Formation ◽  
Laplace Transforms ◽  
Discrete Models ◽  
Average Error ◽  
Growth Substrate ◽  
Substrate Consumption ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mathematical Techniques ◽  
Discrete Time Models

Abstract The Z- and Laplace transforms are mathematical techniques applied to solve difference equations and differential equations, respectively. Mathematical models used to describe cell growth, substrate consumption and product formation in bioprocesses can be represented by these types of equations. Thus, in this work, the fermentation process of the yeast Saccharomyces cerevisiae was modeled using different models from the literature, and the Z- and Laplace transforms were applied to solve the equations. Once the equations were solved, the models were represented in state space and simulated in Octave® software. Finally, the models were compared to experimental data from previous studies and to each other. Verhulst was the model that best described the process, with an average error of 4.74% for cell growth and 13.9% for substrate consumption. This work is unprecedented since no works that use the Z transform and discrete models for the representation of fermentation of this yeast were found in the literature. Even more importantly, this work proved that discrete-time models can be applied to bioprocesses with the same precision as continuous-time models.

scholarly journals Distinct Roles for the Yeast Phosphatidylinositol 4-Kinases, Stt4p and Pik1p, in Secretion, Cell Growth, and Organelle Membrane Dynamics

2000 ◽  
Vol 11 (8) ◽  
pp. 2673-2689 ◽  
Author(s):  
Anjon Audhya ◽  
Michelangelo Foti ◽  
Scott D. Emr
Keyword(s):  
Cell Growth ◽  
Membrane Trafficking ◽  
Secretory Pathway ◽  
Membrane Dynamics ◽  
Small Gtpase ◽  
Effector Proteins ◽  
Restrictive Temperature ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cytoskeleton Organization ◽  
Yeast Viability

The yeast Saccharomyces cerevisiae possesses two genes that encode phosphatidylinositol (PtdIns) 4-kinases,STT4 and PIK1. Both gene products phosphorylate PtdIns at the D-4 position of the inositol ring to generate PtdIns(4)P, which plays an essential role in yeast viability because deletion of either STT4 orPIK1 is lethal. Furthermore, although both enzymes have the same biochemical activity, increased expression of either kinase cannot compensate for the loss of the other, suggesting that these kinases regulate distinct intracellular functions, each of which is required for yeast cell growth. By the construction of temperature-conditional single and double mutants, we have found that Stt4p activity is required for the maintenance of vacuole morphology, cell wall integrity, and actin cytoskeleton organization. In contrast, Pik1p is essential for normal secretion, Golgi and vacuole membrane dynamics, and endocytosis. Strikingly,pik1tscells exhibit a rapid defect in secretion of Golgi-modified secretory pathway cargos, Hsp150p and invertase, whereas stt4tscells exhibit no detectable secretory defects. Both single mutants reduce PtdIns(4)P by ∼50%; however,stt4ts/pik1tsdouble mutant cells produce more than 10-fold less PtdIns(4)P as well as PtdIns(4,5)P2. The aberrant Golgi morphology found in pik1tsmutants is strikingly similar to that found in cells lacking the function of Arf1p, a small GTPase that is known to regulate multiple membrane trafficking events throughout the cell. Consistent with this observation, arf1 mutants exhibit reduced PtdIns(4)P levels. In contrast, diminished levels of PtdIns(4)P observed in stt4tscells at restrictive temperature result in a dramatic change in vacuole size compared with pik1tscells and persistent actin delocalization. Based on these results, we propose that Stt4p and Pik1p act as the major, if not the only, PtdIns 4-kinases in yeast and produce distinct pools of PtdIns(4)P and PtdIns(4,5)P2that act on different intracellular membranes to recruit or activate as yet uncharacterized effector proteins.

scholarly journals On the Fundamental Physical Constants: II. Field Coupling Geometry

2017 ◽  
Vol 9 (5) ◽  
pp. 62
Author(s):  
Ogaba Philip Obande
Keyword(s):  
Internal Structure ◽  
Periodic Group ◽  
Fundamental Constant ◽  
Physical Property ◽  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Field Coupling ◽  
Fundamental Physical

We show that the chemical periodic group is geometric and that the fundamental constant FC is an intrinsic physical property of the atom, it is geometric, an invariant 3-D slice of spacetime that constitutes internal structure of the atom.

scholarly journals The Pleckstrin Homology Domain Proteins Slm1 and Slm2 Are Required for Actin Cytoskeleton Organization in Yeast and Bind Phosphatidylinositol-4,5-Bisphosphate and TORC2

2005 ◽  
Vol 16 (4) ◽  
pp. 1883-1900 ◽  
Author(s):  
Maria Fadri ◽  
Alexes Daquinag ◽  
Shimei Wang ◽  
Tao Xue ◽  
Jeannette Kunz
Keyword(s):  
Cell Growth ◽  
Actin Cytoskeleton ◽  
Membrane Dynamics ◽  
Effector Proteins ◽  
Pleckstrin Homology Domain ◽  
Ph Domain ◽  
Pleckstrin Homology ◽  
Yeast Saccharomyces Cerevisiae ◽  
Actin Organization ◽  
Cytoskeleton Organization

Phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] is a key second messenger that regulates actin and membrane dynamics, as well as other cellular processes. Many of the effects of PtdIns(4,5)P2are mediated by binding to effector proteins that contain a pleckstrin homology (PH) domain. Here, we identify two novel effectors of PtdIns(4,5)P2in the budding yeast Saccharomyces cerevisiae: the PH domain containing protein Slm1 and its homolog Slm2. Slm1 and Slm2 serve redundant roles essential for cell growth and actin cytoskeleton polarization. Slm1 and Slm2 bind PtdIns(4,5)P2through their PH domains. In addition, Slm1 and Slm2 physically interact with Avo2 and Bit61, two components of the TORC2 signaling complex, which mediates Tor2 signaling to the actin cytoskeleton. Together, these interactions coordinately regulate Slm1 targeting to the plasma membrane. Our results thus identify two novel effectors of PtdIns(4,5)P2regulating cell growth and actin organization and suggest that Slm1 and Slm2 integrate inputs from the PtdIns(4,5)P2and TORC2 to modulate polarized actin assembly and growth.

scholarly journals Rescue of cell growth by sphingosine with disruption of lipid microdomain formation in Saccharomyces cerevisiae deficient in sphingolipid biosynthesis

2006 ◽  
Vol 394 (1) ◽  
pp. 237-242 ◽  
Author(s):  
Motohiro Tani ◽  
Akio Kihara ◽  
Yasuyuki Igarashi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Serine Palmitoyltransferase ◽  
Kinase Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Long Chain Base ◽  
Triton X ◽  
Lipid Microdomain ◽  
Sphingolipid Biosynthesis ◽  
Complex Sphingolipids

In the yeast Saccharomyces cerevisiae, sphingolipids are essential for cell growth. Inactivation of sphingolipid biosynthesis, such as by disrupting the serine palmitoyltransferase gene (LCB2), is lethal, but cells can be rescued by supplying an exogenous LCB (long-chain base) like PHS (phytosphingosine) or DHS (dihydrosphingosine). In the present study, supplying SPH (sphingosine), an unnatural LCB for yeast, similarly rescued the Δlcb2 cells, but only when SPH 1-phosphate production was inhibited by deleting the LCB kinase gene LCB4. Exogenously added SPH was adequately converted into phosphoinositol-containing complex sphingolipids. Interestingly, cells carrying SPH-based sphingolipids exhibited a defect in the association of Pma1p with Triton X-100-insoluble membrane fractions, and displayed sensitivities to both Ca2+ and hygromycin B. These results suggest that the SPH-based sphingolipids in these cells have properties that differ from those of the PHS- or DHS-based sphingolipids in regard to lipid microdomain formation, leading to abnormal sensitivities towards certain environmental stresses. The present paper is the first report showing that in sphingolipid-deficient S. cerevisiae, the requirement for LCB can be fulfilled by exogenous SPH, although this supplement results in failure of lipid microdomain formation.

scholarly journals Pib2 as an Emerging Master Regulator of Yeast TORC1

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1489
Author(s):  
Riko Hatakeyama
Keyword(s):  
Cell Growth ◽  
Growth Regulation ◽  
Model Organisms ◽  
Phosphate Binding ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cellular Events ◽  
Evolutionarily Conserved ◽  
Multiple Groups ◽  
Phosphate Binding Protein ◽  
Enormous Number

Cell growth is dynamically regulated in response to external cues such as nutrient availability, growth factor signals, and stresses. Central to this adaptation process is the Target of Rapamycin Complex 1 (TORC1), an evolutionarily conserved kinase complex that fine-tunes an enormous number of cellular events. How upstream signals are sensed and transmitted to TORC1 has been intensively studied in major model organisms including the budding yeast Saccharomyces cerevisiae. This field recently saw a breakthrough: the identification of yeast phosphatidylInositol(3)-phosphate binding protein 2 (Pib2) protein as a critical regulator of TORC1. Although the study of Pib2 is still in its early days, multiple groups have provided important mechanistic insights on how Pib2 relays nutrient signals to TORC1. There remain, on the other hand, significant gaps in our knowledge and mysteries that warrant further investigations. This is the first dedicated review on Pib2 that summarizes major findings and outstanding questions around this emerging key player in cell growth regulation.

The Complex Genetic Basis and Multilayered Regulatory Control of Yeast Pseudohyphal Growth

2021 ◽  
Vol 55 (1) ◽  
Author(s):  
Anuj Kumar
Keyword(s):  
Cell Growth ◽  
Signaling Pathways ◽  
Single Cells ◽  
Regulatory Control ◽  
Yeast Cells ◽  
Regulatory Mechanisms ◽  
Annual Review ◽  
Publication Date ◽  
Yeast Saccharomyces Cerevisiae ◽  
Pseudohyphal Growth

Eukaryotic cells are exquisitely responsive to external and internal cues, achieving precise control of seemingly diverse growth processes through a complex interplay of regulatory mechanisms. The budding yeast Saccharomyces cerevisiae provides a fascinating model of cell growth in its stress-responsive transition from planktonic single cells to a filamentous pseudohyphal growth form. During pseudohyphal growth, yeast cells undergo changes in morphology, polarity, and adhesion to form extended and invasive multicellular filaments. This pseudohyphal transition has been studied extensively as a model of conserved signaling pathways regulating cell growth and for its relevance in understanding the pathogenicity of the related opportunistic fungus Candida albicans, wherein filamentous growth is required for virulence. This review highlights the broad gene set enabling yeast pseudohyphal growth, signaling pathways that regulate this process, the role and regulation of proteins conferring cell adhesion, and interesting regulatory mechanisms enabling the pseudohyphal transition. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

High Thermal Conductivity Materials

MRS Bulletin ◽  
2001 ◽  
Vol 26 (6) ◽  
pp. 440-444 ◽  
Author(s):  
Koji Watari ◽  
Subhash L. Shinde
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Physical Property ◽  
University Student ◽  
High Thermal Conductivity ◽  
Theoretical Support ◽  
Initial Work ◽  
Fundamental Physical Property ◽  
Good Conductor ◽  
Fundamental Physical

Every university student becomes familiar with the concept of thermal conductivity, a fundamental physical property of materials, through his or her textbooks. Initial work on high thermal conductivity was carried out in 1911 by Eucken, who discovered that diamond was a reasonably good conductor for heat at room temperature. Theoretical support for this discovery was established by Debye in 1914.

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