scholarly journals Autotoxin-mediated voluntary triage in starved yeast community

2020 ◽  
Author(s):  
Arisa H. Oda ◽  
Miki Tamura ◽  
Kunihiko Kaneko ◽  
Kunihiro Ohta ◽  
Tetsuhiro S. Hatakeyama
Keyword(s):  
Environmental Changes ◽  
Yeast Cells ◽  
Glucose Starvation ◽  
Uniform Stress ◽  
Universal System ◽  
Stressful Environment ◽  
Yeast Community ◽  
Unicellular Organisms ◽  
Multicellular Organisms ◽  
Cell Community

When organisms face crises, such as starvation, every individual should adapt to environmental changes (1, 2), or the community alters their behaviour (3–5). Because a stressful environment reduces the carrying capacity (6), the population size of unicellular organisms shrinks in such conditions (7, 8). However, the uniform stress response of the cell community may lead to overall extinction or severely damage their entire fitness. How microbial communities accommodate this dilemma remains poorly understood. Here, we demonstrate an elaborate strategy of the yeast community against glucose starvation, named the voluntary triage. During starvation, yeast cells release some autotoxins, such as leucic acid and L-2keto-3methylvalerate, which can even kill the cells producing them. Although it may look like mass suicide at first glance, cells use epigenetic “tags” to adapt to the autotoxin inheritably. If non-tagged latecomers, regardless of whether they are closely related, try to invade the habitat, autotoxins kill them and inhibit their growth, but the tagged cells can selectively survive. Phylogenetically distant fission and budding yeast (9) share this strategy using the same autotoxins, which implies that the universal system of voluntary triage may be relevant to the major evolutional transition from unicellular to multicellular organisms (10).

scholarly journals Human Bak induces cell death in Schizosaccharomyces pombe with morphological changes similar to those with apoptosis in mammalian cells.

1997 ◽  
Vol 17 (5) ◽  
pp. 2468-2474 ◽  
Author(s):  
B Ink ◽  
M Zörnig ◽  
B Baum ◽  
N Hajibagheri ◽  
C James ◽  
...  
Keyword(s):  
Cell Death ◽  
Schizosaccharomyces Pombe ◽  
Mammalian Cells ◽  
Morphological Changes ◽  
Yeast Cells ◽  
Bh3 Domain ◽  
Evolutionarily Conserved ◽  
Unicellular Organisms ◽  
Induction Of Apoptosis ◽  
Multicellular Organisms

Apoptosis as a form of programmed cell death (PCD) in multicellular organisms is a well-established genetically controlled process that leads to elimination of unnecessary or damaged cells. Recently, PCD has also been described for unicellular organisms as a process for the socially advantageous regulation of cell survival. The human Bcl-2 family member Bak induces apoptosis in mammalian cells which is counteracted by the Bcl-x(L) protein. We show that Bak also kills the unicellular fission yeast Schizosaccharomyces pombe and that this is inhibited by coexpression of human Bcl-x(L). Moreover, the same critical BH3 domain of Bak that is required for induction of apoptosis in mammalian cells is also required for inducing death in yeast. This suggests that Bak kills mammalian and yeast cells by similar mechanisms. The phenotype of the Bak-induced death in yeast involves condensation and fragmentation of the chromatin as well as dissolution of the nuclear envelope, all of which are features of mammalian apoptosis. These data suggest that the evolutionarily conserved metazoan PCD pathway is also present in unicellular yeast.

Freezing

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Thermal Hysteresis ◽  
Higher Plants ◽  
Terrestrial Environment ◽  
Cold Temperatures ◽  
Cellular Dehydration ◽  
A Cell ◽  
Unicellular Organisms ◽  
Cell Cytosol ◽  
Freezing Temperatures ◽  
Multicellular Organisms

Freezing is a widespread ecological challenge, affecting organisms in over half the terrestrial environment as well as both polar seas. With very few exceptions, if a cell freezes internally, it dies. Polar teleost fish in shallow waters avoid freezing by synthesising a range of protein or glycoprotein antifreezes. Terrestrial organisms are faced with a far greater thermal challenge, and exhibit a more complex array of responses. Unicellular organisms survive freezing temperatures by preventing ice nucleating within the cytosol, and tolerating the cellular dehydration and membrane disruption that follows from ice forming in the external environment. Multicellular organisms survive freezing temperatures by manipulating the composition of the extracellular body fluids. Terrestrial organisms may freeze at high subzero temperatures, often promoted by ice nucleating proteins, and small molecular mass cryoprotectants (often sugars and polyols) moderate the osmotic stress on cells. A range of chaperone proteins (dehydrins, LEA proteins) help maintain the integrity of membranes and macromolecules. Thermal hysteresis (antifreeze) proteins prevent damaging recrystallisation of ice. In some cases arthropods and higher plants prevent freezing in their extracellular fluids and survive by supercooling. Vitrification of extracellular water, or of the cell cytosol, may be a more widespread response to very cold temperatures than recognised to date.

scholarly journals AMPK and vacuole-associated Atg14p orchestrate μ-lipophagy for energy production and long-term survival under glucose starvation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Arnold Y Seo ◽  
Pick-Wei Lau ◽  
Daniel Feliciano ◽  
Prabuddha Sengupta ◽  
Mark A Le Gros ◽  
...  
Keyword(s):  
Energy Source ◽  
Energy Production ◽  
Alternative Energy ◽  
Yeast Cells ◽  
Survival Strategies ◽  
Glucose Starvation ◽  
Term Survival ◽  
Long Term Survival ◽  
Glucose Depletion

Dietary restriction increases the longevity of many organisms, but the cell signaling and organellar mechanisms underlying this capability are unclear. We demonstrate that to permit long-term survival in response to sudden glucose depletion, yeast cells activate lipid-droplet (LD) consumption through micro-lipophagy (µ-lipophagy), in which fat is metabolized as an alternative energy source. AMP-activated protein kinase (AMPK) activation triggered this pathway, which required Atg14p. More gradual glucose starvation, amino acid deprivation or rapamycin did not trigger µ-lipophagy and failed to provide the needed substitute energy source for long-term survival. During acute glucose restriction, activated AMPK was stabilized from degradation and interacted with Atg14p. This prompted Atg14p redistribution from ER exit sites onto liquid-ordered vacuole membrane domains, initiating µ-lipophagy. Our findings that activated AMPK and Atg14p are required to orchestrate µ-lipophagy for energy production in starved cells is relevant for studies on aging and evolutionary survival strategies of different organisms.

scholarly journals Antimicrobial peptides and bacteriocins: alternatives to traditional antibiotics

2008 ◽  
Vol 9 (2) ◽  
pp. 227-235 ◽  
Author(s):  
Yongming Sang ◽  
Frank Blecha
Keyword(s):  
Antimicrobial Peptides ◽  
Membrane Integrity ◽  
Principal Component ◽  
Protective Response ◽  
Antimicrobial Drugs ◽  
Induce Resistance ◽  
Unicellular Organisms ◽  
Conventional Antibiotics ◽  
Multicellular Organisms ◽  
Recent Attention

AbstractAntimicrobial peptides (AMPs) are ubiquitous, gene-encoded natural antibiotics that have gained recent attention in the search for new antimicrobials to combat infectious disease. In multicellular organisms, AMPs, such as defensins and cathelicidins, provide a coordinated protective response against infection and are a principal component of innate immunity in vertebrates. In unicellular organisms, AMPs, such as bacteriocins, function to suppress competitor species. Because many AMPs kill bacteria by disruption of membrane integrity and are thus thought to be less likely to induce resistance, AMPs are being extensively evaluated as novel antimicrobial drugs. This review summarizes and discusses the antibiotic properties of AMPs highlighting their potential as alternatives to conventional antibiotics.

scholarly journals Loss of GET pathway orthologs inArabidopsis thalianacauses root hair growth defects and affects SNARE abundance

2017 ◽  
Vol 114 (8) ◽  
pp. E1544-E1553 ◽  
Author(s):  
Shuping Xing ◽  
Dietmar Gerald Mehlhorn ◽  
Niklas Wallmeroth ◽  
Lisa Yasmin Asseck ◽  
Ritwika Kar ◽  
...  
Keyword(s):  
Root Hair ◽  
Yeast Cells ◽  
Hydrophobic Domain ◽  
Protein Insertion ◽  
Cellular Processes ◽  
Growth Defects ◽  
Protein Receptor ◽  
Root Hair Growth ◽  
Multicellular Organisms ◽  
Ta Proteins

SolubleN-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) proteins are key players in cellular trafficking and coordinate vital cellular processes, such as cytokinesis, pathogen defense, and ion transport regulation. With few exceptions, SNAREs are tail-anchored (TA) proteins, bearing a C-terminal hydrophobic domain that is essential for their membrane integration. Recently, the Guided Entry of Tail-anchored proteins (GET) pathway was described in mammalian and yeast cells that serve as a blueprint of TA protein insertion [Schuldiner M, et al. (2008)Cell134(4):634–645; Stefanovic S, Hegde RS (2007)Cell128(6):1147–1159]. This pathway consists of six proteins, with the cytosolic ATPase GET3 chaperoning the newly synthesized TA protein posttranslationally from the ribosome to the endoplasmic reticulum (ER) membrane. Structural and biochemical insights confirmed the potential of pathway components to facilitate membrane insertion, but the physiological significance in multicellular organisms remains to be resolved. Our phylogenetic analysis of 37 GET3 orthologs from 18 different species revealed the presence of two different GET3 clades. We identified and analyzed GET pathway components inArabidopsis thalianaand found reduced root hair elongation inAtgetlines, possibly as a result of reduced SNARE biogenesis. Overexpression ofAtGET3a in a receptor knockout (KO) results in severe growth defects, suggesting presence of alternative insertion pathways while highlighting an intricate involvement for the GET pathway in cellular homeostasis of plants.

scholarly journals Yeast cells under glucose-limitation environment need increased response cost for osmostress defense

2021 ◽  
Author(s):  
Chunxiong Luo ◽  
Wenting Shen ◽  
Ziqing Gao ◽  
Kaiyue Chen ◽  
Qi Ouyang
Keyword(s):  
Cell Growth ◽  
Environmental Changes ◽  
Yeast Cells ◽  
Protein Accumulation ◽  
Response Cost ◽  
Glucose Limitation ◽  
Dynamic Expression ◽  
Normal Glucose ◽  
Low Glucose ◽  
Glucose Condition

Cells always make responses to environmental changes, involving dynamic expression of tens to hundreds of proteins. This response system may demand substantial cost and thus affect cell growth. Here, we studied the cell's responses to osmostress under glucose-limitation environments. Through analyzed thirteen osmotic-downstream proteins and two related transcription factors, we found that the cells required stronger responses under low glucose concentrations than normal glucose condition after being stimulated by osmostress, even the cell growth rate was unchanged in these two constant conditions. We proposed and verified that under a glucose-limitation environment, the glycolysis intermediates were limited (defense reserve saving), which caused that cells needed more glycerol production enzymes to adapt to the osmostress. Further experiments proved that this 'defense reserve-saving' strategy required cells to spend more response cost when facing stress, which on the other hand, enhanced the fitness for the coming environment variations via protein accumulation reserve.

Mechanical forces and their second messengers in stimulating cell growth in vitro

1992 ◽  
Vol 262 (3) ◽  
pp. R350-R355 ◽  
Author(s):  
H. H. Vandenburgh
Keyword(s):  
Cell Growth ◽  
Molecular Mechanisms ◽  
Cultured Cells ◽  
Second Messengers ◽  
Second Messenger ◽  
Model Systems ◽  
Mechanical Forces ◽  
Unicellular Organisms ◽  
Multicellular Organisms

Mechanical forces play an important role in modulating the growth of a number of different tissues including skeletal muscle, smooth muscle, cardiac muscle, bone, endothelium, epithelium, and lung. As interest increases in the molecular mechanisms by which mechanical forces are transduced into growth alterations, model systems are being developed to study these processes in tissue culture. This paper reviews the current methods available for mechanically stimulating tissue cultured cells. It then outlines some of the putative “mechanogenic” second messengers involved in altering cell growth. Not surprisingly, many mechanogenic second messengers are the same as those involved in growth factor-induced cell growth. It is hypothesized that from an evolutionary standpoint, some second messenger systems may have initially evolved for unicellular organisms to respond to physical forces such as gravity and mechanical perturbation in their environment. As multicellular organisms came into existence, they appropriated these mechanogenic second messenger cascades for cellular regulation by growth factors.

Cells, Bodies, and Brains

2017 ◽  
Author(s):  
Arlindo Oliveira
Keyword(s):  
Information Processing ◽  
Charles Darwin ◽  
Life Forms ◽  
Eukaryotic Cells ◽  
Complex Cells ◽  
Complex Information ◽  
Complex Information Processing ◽  
Unicellular Organisms ◽  
Multicellular Organisms ◽  
Processing Device

This chapter describes evolution as a long-running algorithm that has designed all species on Earth. Evolution, a process discovered by Charles Darwin, has been working for more than four billion years to obtain, at first, simple unicellular organisms (prokaryotes) and, later, much more complex life forms, based on eukaryotic cells. Evolution worked not with bits stored in a computer memory, but with replicators that are digital sequences written in very long DNA molecules, the genomes. Complex cells, which are the results of this optimization algorithm, eventually organized themselves in vast multi-cellular complexes, leading to the multicellular organisms in existence today and, ultimately, to humans and the human brain, the most complex information processing device we know.

scholarly journals Phagocytosis: a repertoire of receptors and Ca2+ as a key second messenger

2008 ◽  
Vol 28 (5) ◽  
pp. 287-298 ◽  
Author(s):  
Alirio J. Melendez ◽  
Hwee Kee Tay
Keyword(s):  
Phagosome Maturation ◽  
Physiological Event ◽  
Signalling Molecules ◽  
Complex Process ◽  
Large Particles ◽  
A Cell ◽  
Unicellular Organisms ◽  
Multicellular Organisms ◽  
Innate Defence

Receptor-mediated phagocytosis is a complex process that mediates the internalization, by a cell, of other cells and large particles; this is an important physiological event not only in mammals, but in a wide diversity of organisms. Of simple unicellular organisms that use phagocytosis to extract nutrients, to complex metazoans in which phagocytosis is essential for the innate defence system, as a first line of defence against invading pathogens, as well as for the clearance of damaged, dying or dead cells. Evolution has armed multicellular organisms with a range of receptors expressed on many cells that serve as the molecular basis to bring about phagocytosis, regardless of the organism or the specific physiological event concerned. Key to all phagocytic processes is the finely controlled rearrangement of the actin cytoskeleton, in which Ca2+ signals play a major role. Ca2+ is involved in cytoskeletal changes by affecting the actions of a number of contractile proteins, as well as being a cofactor for the activation of a number of intracellular signalling molecules, which are known to play important roles during the initiation, progression and resolution of the phagocytic process. In mammals, the requirement of Ca2+ for the initial steps in phagocytosis, and the subsequent phagosome maturation, can be quite different depending on the type of cell and on the type of receptor that is driving phagocytosis. In this review we discuss the different receptors that mediate professional and non-professional phagocytosis, and discuss the role of Ca2+ in the different steps of this complex process.

scholarly journals Control of cell cycle progression by phosphorylation of cyclin-dependent kinase (CDK) substrates

2010 ◽  
Vol 30 (4) ◽  
pp. 243-255 ◽  
Author(s):  
Randy Suryadinata ◽  
Martin Sadowski ◽  
Boris Sarcevic
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Cycle Progression ◽  
Genetic Material ◽  
Eukaryotic Cell ◽  
S Phase ◽  
Cycle Progression ◽  
M Phase ◽  
Unicellular Organisms ◽  
Multicellular Organisms

The eukaryotic cell cycle is a fundamental evolutionarily conserved process that regulates cell division from simple unicellular organisms, such as yeast, through to higher multicellular organisms, such as humans. The cell cycle comprises several phases, including the S-phase (DNA synthesis phase) and M-phase (mitotic phase). During S-phase, the genetic material is replicated, and is then segregated into two identical daughter cells following mitotic M-phase and cytokinesis. The S- and M-phases are separated by two gap phases (G1 and G2) that govern the readiness of cells to enter S- or M-phase. Genetic and biochemical studies demonstrate that cell division in eukaryotes is mediated by CDKs (cyclin-dependent kinases). Active CDKs comprise a protein kinase subunit whose catalytic activity is dependent on association with a regulatory cyclin subunit. Cell-cycle-stage-dependent accumulation and proteolytic degradation of different cyclin subunits regulates their association with CDKs to control different stages of cell division. CDKs promote cell cycle progression by phosphorylating critical downstream substrates to alter their activity. Here, we will review some of the well-characterized CDK substrates to provide mechanistic insights into how these kinases control different stages of cell division.

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