Influence of carbon source and surface hydrophobicity on the aggregation of the yeastKluyveromyces bulgaricus

2005 ◽  
Vol 51 (1) ◽  
pp. 91-94 ◽  
Author(s):  
F Thiebault ◽  
J Coulon
Keyword(s):  
Carbon Source ◽  
Fluorescence Probe ◽  
Free Acid ◽  
Surface Hydrophobicity ◽  
Yeast Cells ◽  
Calcium Dependent ◽  
Hydrophobic Amino Acids ◽  
Free Acid Form ◽  
Sigma Chemical ◽  
Hydrophobic Areas

Aggregation of the yeast Kluyveromyces bulgaricus is mediated by the galactose-specific lectin KbCWL1. This lectin contains hydrophobic amino acids and its activity is calcium dependent. A specific fluorescent probe, 1-anilinonaphthalene-8-sulfonic acid in the free acid form (ANS; Sigma Chemical Co., St. Louis, Missouri), was used to study the hydrophobic areas on the cellular surface of K. bulgaricus. Changes in surface hydrophobicity during the growth and aggregation of yeast cells were studied. Surface hydrophobicity increased during growth and depended on the amount of yeast cells in the culture medium. During growth, the size of the hydrophobic areas on the cell surface was measured using ANS and was found to increase with the percentage of flocculating yeasts. Our results strongly suggest that the hydrophobic areas of the cell walls of yeast cells are involved in the aggregation of K. bulgaricus.Key words: aggregation, carbon source, fluorescence probe, hydrophobicity, yeast.

Calcium ion imaging in plant cells

1993 ◽  
Vol 51 ◽  
pp. 132-133
Author(s):  
Peter K. Hepler ◽  
Dale A. Callaham
Keyword(s):  
Plant Cell Wall ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Free Acid ◽  
Methyl Esters ◽  
Free Calcium ◽  
Local Concentration ◽  
Ion Imaging ◽  
Membrane Compartments ◽  
Free Acid Form

Calcium ions (Ca) participate in many signal transduction processes, and for that reason it is important to determine where these ions are located within the living cell, and when and to what extent they change their local concentration. Of the different Ca-specific indicators, the fluorescent dyes, developed by Grynkiewicz et al. (1), have proved most efficacious, however, their use on plants has met with several problems (2). First, the dyes as acetoxy-methyl esters are often cleaved by extracellular esterases in the plant cell wall, and thus they do not enter the cell. Second, if the dye crosses the plasma membrane it may continue into non-cytoplasmic membrane compartments. Third, even if cleaved by esterases in the cytoplasm, or introduced as the free acid into the cytoplasmic compartment, the dyes often become quickly sequestered into vacuoles and organelles, or extruded from the cell. Finally, the free acid form of the dye readily complexes with proteins reducing its ability to detect free calcium. All these problems lead to an erroneous measurement of calcium (2).

Identification of an upstream activating sequence and an upstream repressible sequence of the pyruvate kinase gene of the yeast Saccharomyces cerevisiae

1989 ◽  
Vol 9 (2) ◽  
pp. 442-451
Author(s):  
M Nishizawa ◽  
R Araki ◽  
Y Teranishi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Pyruvate Kinase ◽  
Transcriptional Activation ◽  
Regulatory Elements ◽  
Noncoding Region ◽  
Yeast Cells ◽  
Kinase Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Upstream Activating Sequence

To clarify carbon source-dependent control of the glycolytic pathway in the yeast Saccharomyces cerevisiae, we have initiated a study of transcriptional regulation of the pyruvate kinase gene (PYK). By deletion analysis of the 5'-noncoding region of the PYK gene, we have identified an upstream activating sequence (UASPYK1) located between 634 and 653 nucleotides upstream of the initiating ATG codon. The promoter activity of the PYK 5'-noncoding region was abolished when the sequence containing the UASPYK1 was deleted from the region. Synthetic UASPYK1 (26mer), in either orientation, was able to restore the transcriptional activity of UAS-depleted mutants when placed upstream of the TATA sequence located at -199 (ATG as +1). While the UASPYK1 was required for basal to intermediate levels of transcriptional activation, a sequence between -714 and -811 was found to be necessary for full activation. On the other hand, a sequence between -344 and -468 was found to be responsible for transcriptional repression of the PYK gene when yeast cells were grown on nonfermentable carbon sources. This upstream repressible sequence also repressed transcription, although to a lesser extent, when glucose was present in the medium. The possible mechanism for carbon source-dependent regulation of PYK expression through these cis-acting regulatory elements is discussed.

An ATP-sensitive conductance in cultured smooth muscle cells from pregnant rat myometrium

1989 ◽  
Vol 257 (2) ◽  
pp. C297-C305 ◽  
Author(s):  
E. Honore ◽  
C. Martin ◽  
C. Mironneau ◽  
J. Mironneau
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Voltage Clamp ◽  
Free Acid ◽  
Muscle Cells ◽  
Monovalent Cation ◽  
Acid Form ◽  
Pregnant Rat ◽  
Free Acid Form ◽  
Cultured Smooth Muscle Cells

The whole cell voltage-clamp technique was used to study the effects of extracellular ATP in cultured smooth muscle cells isolated from pregnant rat myometrium. An inward current was elicited by ATP (IATP) in cells held at -70 mV under voltage clamp. The amplitude of IATP was reduced by estrogen pretreatment and by the end of pregnancy. IATP not only did not undergo any desensitization but showed facilitation. The current-voltage relationship of IATP was linear and reversed close to 0 mV. Changing the sodium electrochemical gradient by decreasing extracellular or intracellular sodium resulted in a linear relationship between the reversal potential of IATP and Na equilibrium potential that, however, differed from the predicted curve for a purely sodium conductance. The conductance activated by ATP was monovalent cation selective with little discrimination between potassium, cesium, and sodium ions. IATP was depressed by divalent cations, and the rank order of potency was Co greater than Mg greater than Ca greater than Ba, suggesting that the free-acid form of ATP was the effective ligand. Adenosine, AMP, and ADP were ineffective in eliciting IATP, whereas ATP gamma S and alpha,beta-methylene ATP were capable of mimicking the effects of ATP, although they were less potent. These results are consistent with the free-acid form of ATP activating a monovalent cation-selective and estrogen-sensitive conductance in myometrium.

Evolution of ethylene by Saccharomyces cerevisiae as influenced by the carbon source for growth and the presence of air

1978 ◽  
Vol 24 (6) ◽  
pp. 637-642 ◽  
Author(s):  
K. C. Thomas ◽  
Mary Spencer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Ethylene Production ◽  
Atp Synthesis ◽  
Yeast Cells ◽  
Yeast Culture ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Absolute Requirement ◽  
Wild Type Yeast

Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied. The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells. Addition of glucose to the lactate-grown yeast culture induced ethylene production. This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide. Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium. The conversion of this precursor to ethylene might be stimulated by oxygen. The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis.

scholarly journals Physiological function of Flo11p domains and the particular role of amyloid core sequences of this adhesin in Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Clara Bouyx ◽  
Marion Schiavone ◽  
Marie-Ange Teste ◽  
Etienne Dague ◽  
Nathalie Sieczkowski ◽  
...  
Keyword(s):  
Cell Wall ◽  
Amyloid Β ◽  
Surface Hydrophobicity ◽  
Yeast Cells ◽  
Invasive Growth ◽  
Specific Domain ◽  
A Genome ◽  
A Cell ◽  
Cellular Aggregates

Flocculins are a family of glycosylated proteins that provide yeast cells with several properties such as biofilm formation, flocculation, invasive growth or formation of velum. These proteins are similarly organised with a N-terminal (adhesion) domain, a stalk-like central B-domain with several repeats and a C-terminal sequence carrying a cell wall anchor site. They also contain amyloid β-aggregation-prone sequences whose functional role is still unclear. In this work, we show that Flo11p differs from other flocculins by the presence of unique amyloid-forming sequences, whose the number is critical in the formation of adhesion nanodomains under a physical shear force. Using a genome editing approach to identify the function of domains in Flo11p phenotypes, we show that the formation of cellular aggregates whose density increases with the number of amyloid sequences cannot be attributed to a specific domain of Flo11p. The same is true for plastic adhesion and surface hydrophobicity the intensity of which depends mainly on the abundance of Flo11p on the cell surface. In contrast, the N and C domains of Flo11p are essential for invasive growth in agar, whereas a reduction in the number of repeats of the B domain weakens this phenotype. However, expression of FLO11 alone is not sufficient to trigger this invasion phenotype. Finally, we show that this flocculin contributes to the integrity of the cell wall.

The assimilation of different carbon sources in Candida albicans: Fitness and pathogenicity

2020 ◽  
Author(s):  
Bronwyn Lok ◽  
Mowaffaq Adam Ahmad Adam ◽  
Laina Zarisa Mohd Kamal ◽  
Nwakpa Anthony Chukwudi ◽  
Rosline Sandai ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Carbon Source ◽  
Fungal Infections ◽  
Carbon Sources ◽  
Surface Hydrophobicity ◽  
Vital Role ◽  
Infection Process ◽  
The Body ◽  
Mycelial Form ◽  
Cell Wall Biogenesis

Abstract Candida albicans is a commensal yeast commonly found on the skin and in the body. However, in immunocompromised individuals, the fungi could cause local and systemic infections. The carbon source available plays an important role in the establishment of C. albicans infections. The fungi's ability to assimilate a variety of carbon sources plays a vital role in its colonization, and by extension, its fitness and pathogenicity, as it often inhabits niches that are glucose-limited but rich in alternative carbon sources. A difference in carbon sources affect the growth and mating of C. albicans, which contributes to its pathogenicity as proliferation helps the fungi colonize its environment. The carbon source also affects its metabolism and signaling pathways, which are integral parts of the fungi's fitness and pathogenicity. As a big percentage of the carbon assimilated by C. albicans goes to cell wall biogenesis, the availability of different carbon sources will result in cell walls with variations in rigidity, adhesion, and surface hydrophobicity. In addition to the biofilm formation of the fungi, the carbon source also influences whether the fungi grow in yeast- or mycelial-form. Both forms play different roles in C. albicans’s infection process. A better understanding of the role of the carbon sources in C. albicans’s pathogenicity would contribute to more effective treatment solutions for fungal infections.

scholarly journals Determination of the Global Pattern of Gene Expression in Yeast Cells by Intracellular Levels of Guanine Nucleotides

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Andy Hesketh ◽  
Marta Vergnano ◽  
Stephen G. Oliver
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Gene Transcription ◽  
Adenine Nucleotide ◽  
High Energy ◽  
Yeast Cells ◽  
Purine Nucleotides ◽  
Global Pattern ◽  
Content Type

ABSTRACT Correlations between gene transcription and the abundance of high-energy purine nucleotides in Saccharomyces cerevisiae have often been noted. However, there has been no systematic investigation of this phenomenon in the absence of confounding factors such as nutrient status and growth rate, and there is little hard evidence for a causal relationship. Whether transcription is fundamentally responsive to prevailing cellular energetic conditions via sensing of intracellular purine nucleotides, independently of specific nutrition, remains an important question. The controlled nutritional environment of chemostat culture revealed a strong correlation between ATP and GTP abundance and the transcription of genes required for growth. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into S. cerevisiae, permitting analysis of the transcriptional effect of an increased demand for these nucleotides. During steady-state growth using the fermentable carbon source glucose, the futile consumption of ATP led to a decrease in intracellular ATP concentration but an increase in GTP and the guanylate energy charge (GEC). Expression of transcripts encoding proteins involved in ribosome biogenesis, and those controlled by promoters subject to SWI/SNF-dependent chromatin remodelling, was correlated with these nucleotide pool changes. Similar nucleotide abundance changes were observed using a nonfermentable carbon source, but an effect on the growth-associated transcriptional programme was absent. Induction of the GTP-cycling pathway had only marginal effects on nucleotide abundance and gene transcription. The transcriptional response of respiring cells to glucose was dampened in chemostats induced for ATP cycling, but not GTP cycling, and this was primarily associated with altered adenine nucleotide levels. IMPORTANCE This paper investigates whether, independently of the supply of any specific nutrient, gene transcription responds to the energy status of the cell by monitoring ATP and GTP levels. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into the yeast Saccharomyces cerevisiae, and the effect of an increased demand for these purine nucleotides on gene transcription was analyzed. The resulting changes in transcription were most consistently associated with changes in GTP and GEC levels, although the reprogramming in gene expression during glucose repression is sensitive to adenine nucleotide levels. The results show that GTP levels play a central role in determining how genes act to respond to changes in energy supply and that any comprehensive understanding of the control of eukaryotic gene expression requires the elucidation of how changes in guanine nucleotide abundance are sensed and transduced to alter the global pattern of transcription.

scholarly journals New Assay for Measuring Cell Surface Hydrophobicities of Candida dubliniensis andCandida albicans

2001 ◽  
Vol 8 (3) ◽  
pp. 585-587 ◽  
Author(s):  
M. A. Jabra-Rizk ◽  
W. A. Falkler ◽  
W. G. Merz ◽  
T. F. Meiller
Keyword(s):  
Cell Surface ◽  
Anaerobic Bacterium ◽  
Hydrophobic Interactions ◽  
Cell Surface Hydrophobicity ◽  
Fusobacterium Nucleatum ◽  
Surface Hydrophobicity ◽  
Yeast Cells ◽  
Pathogenic Yeast ◽  
Yeast Cell Surface ◽  
The Many

ABSTRACT Hydrophobic interactions, based on cell surface hydrophobicity (CSH), are among the many and varied mechanisms of adherence deployed by the pathogenic yeast Candida albicans. Recently it was shown that, unlike C. albicans, C. dubliniensisis a species that exhibits an outer fibrillar layer consistent with constant CSH. Previously, C. dubliniensis grown at 25 or 37°C was shown to coaggregate with the oral anaerobic bacteriumFusobacterium nucleatum. C. albicans, however, demonstrated similar coaggregation only when hydrophobic or grown at 25°C. This observation implied that coaggregation of Candida cells with F. nucleatum is associated with a hydrophobic yeast cell surface. To test this hypothesis, 42 C. albicans and 40 C. dubliniensis clinical isolates, including a C. albicans hydrophobic variant, were grown at 25 and 37°C and tested with the established hydrophobicity microsphere assay, which determines CSH levels based on the number of microspheres attached to the yeast cells. The coaggregation assay was performed in parallel experiments. All C. dubliniensis isolates grown at either temperature, hydrophobic 25°C-grown C. albicans isolates, and the C. albicans hydrophobic variant, unlike the 37°C-hydrophilic C. albicans isolates, exhibited hydrophobic CSH levels with the microsphere assay and simultaneously showed maximum, 4+, coaggregation with F. nucleatum. The parallel results obtained for C. dubliniensis using both assays support the use of the CoAg assay both as a rapid assay to determine CSH and to differentiate between C. dubliniensisand C. albicans.

EFFECTS OF VARIOUS CHEMICAL AND COLD-HARDENING TREATMENTS ON RESISTANCE OF SUGAR BEET SEEDLINGS TO FREEZING

1956 ◽  
Vol 34 (1) ◽  
pp. 154-158
Author(s):  
William G. Corns
Keyword(s):  
Sugar Beet ◽  
Sodium Salt ◽  
Free Acid ◽  
Cold Hardening ◽  
Chemically Treated ◽  
Free Acid Form ◽  
Series Of Experiments ◽  
The Difference ◽  
And Control ◽  
Low Temperature Resistance

Either the free acid form or the sodium salt of Dalapon (2,2-dichloropropionic acid) and of TCA (trichloroacetic acid) and the sodium salt of 2,2,3-trichloropropionic acid (free acid not tested) were effective in improving the low temperature resistance of sugar beet seedlings grown in 4- and 8-p.p.m. solutions in the dark at 21 °C., and evaluated by short exposures to −10 °C. Isopropy-N(3-chlorophenyl) carbamate, amino triazole, sodium chloride, and trichlorobenzoic acid were ineffective in similar tests. In a series of experiments involving periodic sampling and freezing of Dalapon-treated illuminated sugar beet seedlings during a 24 day period of storage at 6 °C., the chemically treated plants were again superior to the comparable controls. The "cold-hardening" treatments tended to increase the magnitude of the difference between chemically treated and control plants. The amount of improvement was more variable in the tests with green plants than with those grown in the dark.

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