scholarly journals Identification of mutants with increased variation in cell size at onset of mitosis in fission yeast

2021 ◽  
pp. jcs.251769
Author(s):  
Elizabeth Wood ◽  
Kazunori Kume ◽  
Francisco J. Navarro ◽  
Paul Nurse
Keyword(s):  
Fission Yeast ◽  
Cell Size ◽  
Wild Type Strain ◽  
Cell Length ◽  
Yeast Cells ◽  
Wild Type ◽  
Gene Deletions ◽  
Cytoplasmic Transport ◽  
Dividing Cells ◽  
The Mean

Fission yeast cells divide at a similar cell length with little variation about the mean. This is thought to be the result of a control mechanism that senses size and corrects for any deviations by advancing or delaying onset of mitosis. Gene deletions that advance cells into mitosis at a smaller size or delay cells entering mitosis, have identified genes potentially involved in this mechanism. However, the molecular basis of this control is still not understood. In this work, we have screened for genes, which when deleted, increase the variability in size of dividing cells. The strongest candidate of this screen was mga2. The mga2 deletion shows a greater variation in cell length at division, with a coefficient of variation (CV) of 15-24% while the wild type strain has a CV of 5-8%. Furthermore, unlike wild type cells, the mga2 deletion cells are unable to correct cell size deviations within one cell cycle. We show that the mga2 gene genetically interacts with nem1 and influences the nuclear membrane, and speculate that it may influence the nucleus/cytoplasmic transport of CDK regulators.

Proportional control of organelle position by a mechanism which similarly monitors cell size of wild type and conical form-mutant Tetrahymena

Development ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 261-274
Author(s):  
Denis H. Lynn
Keyword(s):  
Cell Size ◽  
Tetrahymena Thermophila ◽  
Cell Length ◽  
Basal Bodies ◽  
Wild Type ◽  
Cell Type ◽  
Cell Width ◽  
Dividing Cells ◽  
Conical Form

Distance between mouthparts of dividing cells of wild type and conical form-mutant Tetrahymena thermophila (formerly T. pyriformis syngen 1) is directly proportional to cell size. This distance is related to cell length in both wild type and conical cells although the proportionality is different in each cell type. However, for both wild type and conical cells the distance between mouthparts is directly and similarly proportional to the product of cell length and cell width which is an estimate of cell size. Evidence has been obtained which suggests that the new mouthparts are positioned with reference to the anterior mouthparts rather than to either pole of the cell. Determination of the site of the new mouthparts is not related to the number of basal bodies between the two sets of mouthparts.

scholarly journals The puc1 Cyclin Regulates the G1 Phase of the Fission Yeast Cell Cycle in Response to Cell Size

2000 ◽  
Vol 11 (2) ◽  
pp. 543-554 ◽  
Author(s):  
Cristina Martı́n-Castellanos ◽  
Miguel A. Blanco ◽  
José M. de Prada ◽  
Sergio Moreno
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Size ◽  
Yeast Cells ◽  
G1 Phase ◽  
Close Relative ◽  
Cell Cycle Distribution ◽  
Cdk Inhibitor ◽  
Wild Type ◽  
A Cell

Eukaryotic cells coordinate cell size with cell division by regulating the length of the G1 and G2 phases of the cell cycle. In fission yeast, the length of the G1 phase depends on a precise balance between levels of positive (cig1, cig2, puc1, and cdc13 cyclins) and negative (rum1 and ste9-APC) regulators of cdc2. Early in G1, cyclin proteolysis and rum1 inhibition keep the cdc2/cyclin complexes inactive. At the end of G1, the balance is reversed and cdc2/cyclin activity down-regulates both rum1 and the cyclin-degrading activity of the APC. Here we present data showing that the puc1 cyclin, a close relative of the Cln cyclins in budding yeast, plays an important role in regulating the length of G1. Fission yeast cells lacking cig1 and cig2 have a cell cycle distribution similar to that of wild-type cells, with a short G1 and a long G2. However, when thepuc1 + gene is deleted in this genetic background, the length of G1 is extended and these cells undergo S phase with a greater cell size than wild-type cells. This G1 delay is completely abolished in cells lacking rum1. Cdc2/puc1 function may be important to down-regulate the rum1 Cdk inhibitor at the end of G1.

scholarly journals FK506-binding protein FklB is involved in biofilm formation through its peptidyl-prolyl isomerase activity

2020 ◽  
Author(s):  
Chrysoula Zografou ◽  
Maria Dimou ◽  
Panagiotis Katinakis
Keyword(s):  
Biofilm Formation ◽  
Negative Regulator ◽  
Cell Length ◽  
Wild Type ◽  
Prolyl Isomerase ◽  
Ppiase Activity ◽  
Peptidyl Prolyl Isomerase ◽  
Knock Out ◽  
E Coli ◽  
The Mean

AbstractFklB is a member of the FK506-binding proteins (FKBPs), a family that consists of five genes in Escherichia coli. Little is known about the physiological and functional role of FklB in bacterial movement. In the present study, FklB knock-out mutant ΔfklB presented an increased swarming and swimming motility and biofilm formation phenotype, suggesting that FklB is a negative regulator of these cellular processes. Complementation with Peptidyl-prolyl isomerase (PPIase)-deficient fklB gene (Y181A) revealed that the defects in biofilm formation were not restored by Y181A, indicating that PPIase activity of FklB is modulating biofilm formation in E. coli. The mean cell length of ΔfklB swarming cells was significantly smaller as compared to the wild-type BW25113. Furthermore, the mean cell length of swarming and swimming wild-type and ΔfklB cells overexpressing fklB or Y181A was considerably larger, suggesting that PPIase activity of FklB plays a role in cell elongation and/or cell division. A multi-copy suppression assay demonstrated that defects in motility and biofilm phenotype were compensated by overexpressing sets of PPIase-encoding genes. Taken together, our data represent the first report demonstrating the involvement of FklB in cellular functions of E. coli.

scholarly journals Amino acids whose intracellular levels change most during aging alter chronological lifespan of fission yeast

2020 ◽  
Author(s):  
Charalampos Rallis ◽  
Michael Mülleder ◽  
Graeme Smith ◽  
Yan Zi Au ◽  
Markus Ralser ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fission Yeast ◽  
Yeast Cells ◽  
Total Amino Acid ◽  
Wild Type ◽  
Chronological Lifespan ◽  
Biomarkers Of Aging ◽  
Concentration Changes ◽  
Amino Acid Levels

AbstractAmino acid deprivation or supplementation can affect cellular and organismal lifespan, but we know little about the role of concentration changes in free, intracellular amino acids during aging. Here, we determine free amino-acid levels during chronological aging of non-dividing fission yeast cells. We compare wild-type with long-lived mutant cells that lack the Pka1 protein of the protein kinase A signalling pathway. In wild-type cells, total amino-acid levels decrease during aging, but much less so in pka1 mutants. Two amino acids strongly change as a function of age: glutamine decreases, especially in wild-type cells, while aspartate increases, especially in pka1 mutants. Supplementation of glutamine is sufficient to extend the chronological lifespan of wild-type but not of pka1Δ cells. Supplementation of aspartate, on the other hand, shortens the lifespan of pka1Δ but not of wild-type cells. Our results raise the possibility that certain amino acids are biomarkers of aging, and their concentrations during aging can promote or limit cellular lifespan.

Growth in cell length in the fission yeast Schizosaccharomyces pombe

1985 ◽  
Vol 75 (1) ◽  
pp. 357-376 ◽  
Author(s):  
J.M. Mitchison ◽  
P. Nurse
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Cell Size ◽  
Single Cells ◽  
Temperature Shift ◽  
Time Lapse ◽  
Cell Length ◽  
Wild Type ◽  
Cycle Growth ◽  
A Cell ◽  
Mutant Cells

The cylindrical cells of Schizosaccharomyces pombe grow in length by extension at the ends and not the middle. At the beginning of the cell cycle, growth is restricted to the ‘old end’, which existed in the previous cycle. Later on, the ‘new end’, formed from the septum, starts to grow at a point in the cycle that we have called NETO (‘new end take-off’). Fluorescence microscopy on cells stained with Calcofluor has been used to study NETO in size mutants, in blocked cdc mutants and with different growth temperatures and media. In wild-type cells (strain 972) NETO happens at 0.34 of the cycle with a cell length of 9.5 microns. With size mutants that are smaller at division, NETO takes place at the same size (9.0-9.5 microns) but this is not achieved until later in the cycle. Another control operates in larger size mutants since NETO occurs at the same stage of the cycle (about 0.32) as in wild type but at a larger cell size. This control is probably a requirement to have completed an event in early G2, since most cdc mutant cells blocked before this point in the cycle do not show NETO whereas most of those blocked in late G2 do show it. We conclude that NETO only happens if: (1) the cell length is greater than a critical value of 9.0-9.5 microns; and (2) the cell has traversed the first 0.3-0.35 of the cycle and passed early G2. NETO is delayed in poor media, in which cell size is also reduced. Temperature has little effect on NETO under steady-state conditions, but there is a transient delay for some hours after a temperature shift. NETO is later in another wild-type strain, 132. Time-lapse photomicrography was used to follow the rates of length growth in single cells. Wild-type cells showed two linear segments during the first 75% of the cycle. There was a rate-change point (RCP), coincident with NETO, where the rate of total length extension increased by 35%. This increase was not due simply to the start of new-end growth, since old-end growth slowed down in some cells at the RCP. cdc 11.123 is a mutant in which septation and division is blocked at 35 degrees C but nuclear division continues.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Sml1 Inhibits the DNA Repair Activity of Rev1 in Saccharomyces cerevisiae during Oxidative Stress

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Rui Yao ◽  
Pei Zhou ◽  
Chengjin Wu ◽  
Liming Liu ◽  
Jing Wu
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Survival Rate ◽  
Type Strain ◽  
Mutation Frequency ◽  
Wild Type Strain ◽  
Yeast Cells ◽  
Wild Type ◽  
Content Type

ABSTRACT In Saccharomyces cerevisiae, Y family DNA polymerase Rev1 is involved in the repair of DNA damage by translesion DNA synthesis (TLS). In the current study, to elucidate the role of Rev1 in oxidative stress-induced DNA damage in S. cerevisiae, REV1 was deleted and overexpressed; transcriptome analysis of these mutants along with the wild-type strain was performed to screen potential genes that could be associated with REV1 during response to DNA damage. When the yeast cells were treated with 2 mM H2O2, the deletion of REV1 resulted in a 1.5- and 2.8-fold decrease in the survival rate and mutation frequency, respectively, whereas overexpression of REV1 increased the survival rate and mutation frequency by 1.1- and 2.9-fold, respectively, compared to the survival rate and mutation frequency of the wild-type strain. Transcriptome and phenotypic analyses identified that Sml1 aggravated oxidative stress in the yeast cells by inhibiting the activity of Rev1. This inhibition was due to the physical interaction between the BRCA1 C terminus (BRCT) domain of Rev1 and amino acid residues 36 to 70 of Sml1; the cell survival rate and mutation frequency increased by 1.8- and 3.1-fold, respectively, when this interaction was blocked. We also found that Sml1 inhibited Rev1 phosphorylation under oxidative stress and that deletion of SML1 increased the phosphorylation of Rev1 by 46%, whereas overexpression of SML1 reduced phosphorylation of Rev1. Overall, these findings demonstrate that Sml1 could be a novel regulator that mediates Rev1 dephosphorylation to inhibit its activity during oxidative stress. IMPORTANCE Rev1 was critical for cell growth in S. cerevisiae, and the deletion of REV1 caused a severe growth defect in cells exposed to oxidative stress (2 mM H2O2). Furthermore, we found that Sml1 physically interacted with Rev1 and inhibited Rev1 phosphorylation, thereby inhibiting Rev1 DNA antioxidant activity. These findings indicate that Sml1 could be a novel regulator for Rev1 in response to DNA damage by oxidative stress.

scholarly journals Fission Yeast Cells Grow Approximately Exponentially

2018 ◽  
Author(s):  
Mary Pickering ◽  
Lauren Nicole Hollis ◽  
Edridge D’Souza ◽  
Nicholas Rhind
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Fission Yeast ◽  
Cell Size ◽  
Exponential Growth ◽  
Cell Biology ◽  
Growth Models ◽  
Growth Period ◽  
Yeast Cells ◽  
Yeast Growth

ABSTRACTHow the rate of cell growth is influenced by cell size is a fundamental question of cell biology. The simple model that cell growth is proportional to cell size, based on the proposition that larger cells have proportionally greater synthetic capacity than smaller cells, leads to the predication that the rate of cell growth increases exponentially with cell size. However, other modes of cell growth, including bilinear growth, have been reported. The distinction between exponential and bilinear growth has been explored in particular detail in the fission yeast Schizosaccharomyces pombe. We have revisited the mode of fission yeast cell growth using high-resolution time-lapse microscopy and find, as previously reported, that these two growth models are difficult to distinguish both because of the similarity in shapes between exponential and bilinear curves over the two-fold change in length of a normal cell cycle and because of the substantial biological and experimental noise inherent to these experiments. Therefore, we contrived to have cells grow more than two fold, by holding them in G2 for up to eight hours. Over this extended growth period, in which cells grow up to 5.5-fold, the two growth models diverge to the point that we can confidently exclude bilinear growth as a general model for fission yeast growth. Although the growth we observe is clearly more complicated than predicted by simple exponential growth, we find that exponential growth is a robust approximation of fission yeast growth, both during an unperturbed cell cycle and during extended periods of growth.

scholarly journals The number of cytokinesis nodes in mitotic fission yeast scales with cell volume

2021 ◽  
Author(s):  
Wasim A Sayyad ◽  
Thomas D Pollard
Keyword(s):  
Plasma Membrane ◽  
Fission Yeast ◽  
Large Population ◽  
Yeast Cells ◽  
Wild Type ◽  
Contractile Ring ◽  
Node Number ◽  
Nmt1 Promoter ◽  
Wide Range ◽  
Mutant Cells

Cytokinesis nodes are assemblies of stoichiometric ratios of proteins associated with the plasma membrane, which serve as precursors for the contractile ring during cytokinesis by fission yeast. The total number of nodes is uncertain, because of the limitations of the methods used previously. Here we used the ~140 nm resolution of Airyscan confocal microscopy to resolve a large population of dim, unitary cytokinesis nodes in 3D reconstructions of whole fission yeast cells. Wild-type fission yeast cells make about 200 unitary cytokinesis nodes. Most, but not all of these nodes condense into a contractile ring. The number of cytokinesis nodes scales with cell size in four strains tested, although wide rga4Δ mutant cells form somewhat fewer cytokinesis nodes than expected from the overall trend. The surface density of Pom1 kinase on the plasma membrane around the equators of cells is similar with a wide range of node numbers, so Pom1 does not control cytokinesis node number. However, varying protein concentrations with the nmt1 promoter showed that the numbers of nodes increase above a baseline of about 200 with the total cellular concentration of either Pom1 or the kinase Cdr2.

scholarly journals Control of β-glucan exposure by the endo-1,3-glucanase Eng1 in Candida albicans modulates virulence

2020 ◽  
Author(s):  
Mengli Yang ◽  
Norma V. Solis ◽  
Michaela Marshall ◽  
Rachel Garleb ◽  
Tingting Zhou ◽  
...  
Keyword(s):  
Immune Response ◽  
Candida Albicans ◽  
Innate Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Innate Immune ◽  
Yeast Cells ◽  
Parallel Mechanisms ◽  
Wild Type ◽  
Lectin Receptor

AbstractCandida albicans is a major cause of invasive candidiasis, which has a high mortality rate. The hyphal form of C. albicans is virulent and activates the host innate immune response, while the yeast form is hypovirulent and less immunogenic. The innate immune response is critical for host defense, but overactivation can cause tissue damage and sepsis. The innate immune response can be triggered when the C-type lectin receptor Dectin-1 recognizes β-glucans, which is protected by the outer mannan layer of the cell wall on C. albicans. Here, we demonstrate that there is low level of Dectin-1 binding at the septum of yeast cells, but high level of Dectin-1 binding over the entire surface of hyphae. We find that β-glucan masking in yeast is controlled by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. An eng1 deletion mutant shows enhanced Dectin-1 binding at the septa, while an eng1 ywp1 double mutant, but not an ywp1 single mutant, shows strong overall Dectin-1 binding. Thus, Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by Dectin-1. In the model of disseminated candidiasis, mice infected with the eng1 deletion mutant showed delayed mortality with an increased renal immune response in males compared to mice infected with the wild-type strain, but earlier mortality with a higher renal immune response in females. Using the eng1 mutant that is specifically defective in β-glucan masking in yeast, this study demonstrates that the level of β-glucan exposure is important for modulating the balance between immune protection and immunopathogenesis.Abstract ImportanceCandida albicans is a major opportunistic fungal pathogen of humans. Systemic Candidiasis has high mortality rates. C. albicans is also a constituent of the human microbiome and found in gastrointestinal and genitourinary tracts of most healthy individuals. C. albicans is able to switch reversibly between yeast and hyphae in response to environmental cues. The hyphal form is virulent, while the yeast form is hypovirulent and less immunogenic. This study demonstrates that β-glucan exposure in yeast is protected by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by the host C-type lectin receptor Dectin-1. The eng1 mutant triggers a higher immune response and leads to earlier mortality compared to the wild-type strain. Thus, β-glucan masking in yeast keeps yeast cells less immunogenic and hypovirulent.

scholarly journals Cell-size regulation in budding yeast does not depend on linear accumulation of Whi5

2020 ◽  
Vol 117 (25) ◽  
pp. 14243-14250 ◽  
Author(s):  
Felix Barber ◽  
Ariel Amir ◽  
Andrew W. Murray
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Cell Cycle Regulation ◽  
Budding Yeast ◽  
Size Control ◽  
Size Distributions ◽  
Wild Type ◽  
Gal1 Promoter ◽  
The Mean ◽  
Cycle Regulation

Cells must couple cell-cycle progress to their growth rate to restrict the spread of cell sizes present throughout a population. Linear, rather than exponential, accumulation of Whi5, was proposed to provide this coordination by causing a higher Whi5 concentration in cells born at a smaller size. We tested this model using the inducibleGAL1promoter to make the Whi5 concentration independent of cell size. At an expression level that equalizes the mean cell size with that of wild-type cells, the size distributions of cells with galactose-induced Whi5 expression and wild-type cells are indistinguishable. Fluorescence microscopy confirms that the endogenous andGAL1promoters produce different relationships between Whi5 concentration and cell volume without diminishing size control in the G1 phase. We also expressed Cln3 from the GAL1 promoter, finding that the spread in cell sizes for an asynchronous population is unaffected by this perturbation. Our findings indicate that size control in budding yeast does not fundamentally originate from the linear accumulation of Whi5, contradicting a previous claim and demonstrating the need for further models of cell-cycle regulation to explain how cell size controls passage through Start.

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