Morphological commitment in Candida albicans

1981 ◽  
Vol 27 (1) ◽  
pp. 131-137 ◽  
Author(s):  
W. LaJean Chaffin ◽  
Donald E. Wheeler
Keyword(s):  
Stationary Phase ◽  
Cell Volume ◽  
Germ Tube ◽  
Temperature Shift ◽  
Tube Formation ◽  
Yeast Cells ◽  
Volume Distribution ◽  
Dimorphic Fungus ◽  
Bud Formation ◽  
Bud Emergence

Stationary phase yeast cells of the dimorphic fungus albicans can reinitiate growth under appropriate conditions either as yeasts through bud formation or as hyphae through germ tube formation and elongation. Stationary phase yeast cells resuspended in fresh medium at 37 °C form germ tubes and those resuspended at 25 °C form buds. Temperature shift experiments have been used to observe when cells become committed to germ tube formation and yeast budding growth under conditions favorable to each form. The two commitment processes appear to be independent and, once initiated, occur at characteristic rates with commitment to germ tube formation preceding commitment to yeast bud formation. The rate of commitment to germ tube formation was consistent with a random process or first-order kinetics. A relationship between cell volume and commitment to yeast growth and bud emergence was consistent with observations of cell volume distribution both in stationary phase cultures and between budded and unbudded cells during resumption of growth at 25 °C.

Nutrient-limited yeast growth in Candida albicans: effect on yeast-mycelial transition

1980 ◽  
Vol 26 (1) ◽  
pp. 102-105 ◽  
Author(s):  
William M. Bell ◽  
W. LaJean Chaffin
Keyword(s):  
Candida Albicans ◽  
Stationary Phase ◽  
Germ Tube ◽  
Specific Effect ◽  
Defined Medium ◽  
Tube Formation ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Limiting Nutrient ◽  
Final Cell Concentration

The yeast-mycelial transition in Candida albicans can be induced from yeast cells grown on minimal defined medium only in stationary phase. This study examined the inducibility of cultures in which growth was limited by the availability of the nutrients, glucose, NH4Cl, or galactose. The results showed that neither stationary phase nor cell cycle stage alone was a sufficient condition to support subsequent germ tube formation. In addition, final cell concentration alone was not a factor in inducibility. When a hundredfold decrease in growth was obtained by limiting any of the nutrients, a loss in inducibility was observed. However, the loss of inducibility differed with the limiting nutrient. Galactose, NH4Cl, and glucose-limited cultures showed respectively 15, 30, and 80% loss of inducibility. Thus the effect was associated with both carbon/energy and nitrogen-limited cells; however, glucose appeared to have a specific effect. These observations suggest that the metabolic state of the stationary phase yeast cell was an important factor in the subsequent ability to respond to conditions inducing germ tube formation.

Differential expression of cytoplasmic proteins during yeast bud and germ tube formation in Candida albicans

1981 ◽  
Vol 27 (6) ◽  
pp. 580-585 ◽  
Author(s):  
Louise A. Brown ◽  
W. LaJean Chaffin
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Germ Tube ◽  
Polyacrylamide Gel Electrophoresis ◽  
Tube Formation ◽  
Yeast Cells ◽  
Cytoplasmic Proteins ◽  
Specific Proteins ◽  
Major Shift ◽  
Dimorphic Yeast

Changes in the identity and quantity of proteins synthesized during morphogenesis may result from alterations in gene expression in the dimorphic yeast Candida albicans. Stationary phase yeast cells, upon resuming growth at 25 °C, form budding yeast and at 37 °C form germ tubes. In order to identify proteins associated with morphogenesis, we compared cytoplasmic proteins synthesized during germ tube and bud formation. Proteins synthesized during this period were labeled at four intervals with either [3H]leucine or [35S]methionine and separated by two-dimensional polyacrylamide gel electrophoresis. This study shows that, of the 230 proteins resolved on each gel, 5 were specific to the yeast morphology and 2 proteins showed reduction in net synthesis in the mycelial phase. There were, however, no mycelium-specific proteins at any labeling period. The majority of proteins were common to both morphologies and showed no major shift in number during resumption of growth. The observations reported here suggest that differential gene expression occurs during morphogenesis of C. albicans.

Differential increase in cytoplasmic pH at bud and germ tube formation in Candida albicans: studies of a nongerminative variant

1994 ◽  
Vol 40 (9) ◽  
pp. 720-723 ◽  
Author(s):  
Simminder Kaur ◽  
Prashant Mishra
Keyword(s):  
Candida Albicans ◽  
Cell Differentiation ◽  
Germ Tube ◽  
Tube Formation ◽  
Morphological Transition ◽  
Cytoplasmic Ph ◽  
Wild Type ◽  
Bud Formation ◽  
Differential Increase ◽  
Intracellular Alkalinization

The changes in cytoplasmic pH (pHi) accompanying the morphological transition of Candida albicans were studied using a nongerminative variant. A transient cytoplasmic alkalinization at the time of evagination was observed in both the variant and its parent. Under zinc-deficient conditions the wild-type cells that formed buds at pH 4.5 and mycelia at pH 6.5 showed an increase in pHi of 0.58 and 0.12 pH units, respectively. Under similar conditions the pHi of the nongerminative variant that formed buds at both pH 4.5 and 6.5 increased by 0.66 and 0.40 pH units, respectively, suggesting that a greater magnitude of increase in pHi at the time of evagination is probably needed for bud formation. These results provide evidence for a correlation between intracellular alkalinization and time of cell differentiation in C. albicans.Key words: C. albicans, cytoplasmic pH, morphogenesis, nongerminative variant.

A putative dual-specific protein phosphatase encoded by YVH1 controls growth, filamentation and virulence in Candida albicans

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2223-2232 ◽  
Author(s):  
Nozomu Hanaoka ◽  
Takashi Umeyama ◽  
Keigo Ueno ◽  
Kenji Ueda ◽  
Teruhiko Beppu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Candida Albicans ◽  
Cell Cycle Progression ◽  
Germ Tube ◽  
Hyphal Growth ◽  
Tube Formation ◽  
Yeast Cells ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Cycle Progression

In response to stimulants, such as serum, the yeast cells of the opportunistic fungal pathogen Candida albicans form germ tubes, which develop into hyphae. Yvh1p, one of the 29 protein phosphatases encoded in the C. albicans genome, has 45 % identity with the dual-specific phosphatase Yvh1p of the model yeast Saccharomyces cerevisiae. In this study, Yvh1p expression was not observed during the initial step of germ tube formation, although Yvh1p was expressed constitutively in cell cycle progression of yeast or hyphal cells. In an attempt to analyse the function of Yvh1p phosphatase, the complete ORFs of both alleles were deleted by replacement with hph200–URA3–hph200 and ARG4. Although YVH1 has nine single-nucleotide polymorphisms in its coding sequence, both YVH1 alleles were able to complement the YVH1 gene disruptant. The vegetative growth of Δyvh1 was significantly slower than the wild-type. The hyphal growth of Δyvh1 on agar, or in a liquid medium, was also slower than the wild-type because of the delay in nuclear division and septum formation, although germ tube formation was similar between the wild-type and the disruptant. Despite the slow hyphal growth, the expression of several hypha-specific genes in Δyvh1 was not delayed or repressed compared with that of the wild-type. Infection studies using mouse models revealed that the virulence of Δyvh1 was less than that of the wild-type. Thus, YVH1 contributes to normal vegetative yeast or hyphal cell cycle progression and pathogenicity, but not to germ tube formation.

Identification of the dialysable serum inducer of germ-tube formation in Candida albicans

Microbiology ◽  
2004 ◽  
Vol 150 (9) ◽  
pp. 3041-3049 ◽  
Author(s):  
Debbie A. Hudson ◽  
Quentin L. Sciascia ◽  
Rebecca J. Sanders ◽  
Gillian E. Norris ◽  
Pat J. B. Edwards ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Active Component ◽  
Germ Tube ◽  
Nitrogen Sources ◽  
Hyphal Growth ◽  
Tube Formation ◽  
Size Exclusion ◽  
Yeast Cells ◽  
Induction Medium ◽  
Ph Optimum

Yeast cells of Candida albicans are induced by serum at 37 °C to produce germ tubes, the first step in a transition from yeast to hyphal growth. Previously, it has been shown that the active component is not serum albumin but is present in the dialysable fraction of serum. In this study, serum induction of germ-tube formation is shown to occur even in the presence of added exogenous nitrogen sources and is therefore not signalled by nitrogen derepression. The active component in serum was purified by ion-exchange, reverse-phase and size-exclusion chromatography from the dialysable fraction of serum and was identified by NMR to be d-glucose. Enzymic destruction of glucose, using glucose oxidase, demonstrated that d-glucose was the only active component in these fractions. Induction of germ-tube formation by d-glucose required a temperature of 37 °C and the pH optimum was between pH 7·0 and 8·0. d-Glucose induced germ-tube formation in a panel of clinical isolates of C. albicans. Although d-glucose is the major inducer in serum, a second non-dialysable, trichloroacetic acid precipitable inducer is also present. However, whereas either 1·4 % (v/v) serum or an equivalent concentration of d-glucose induced 50 % germ-tube formation, the non-dialysable component required a 10-fold higher concentration to induce 50 % germ-tube formation. Serum is, therefore, the most effective induction medium for germ-tube formation because it is buffered at about pH 8·5 and contains two distinct inducers (glucose and a non-dialysable component), both active at this pH.

scholarly journals Effects of farnesol and lyticase on the formation of Candida albicans biofilm

2020 ◽  
Vol 13 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
Nadezhda Sachivkina ◽  
Ekaterina Lenchenko ◽  
Dmitri Blumenkrants ◽  
Alfia Ibragimova ◽  
Olga Bazarkina
Keyword(s):  
Candida Albicans ◽  
Germ Tube ◽  
Tube Formation ◽  
Host Cells ◽  
Dimorphic Fungus ◽  
Chromogenic Medium ◽  
Fungal Cell ◽  
Treatment Groups ◽  
Bacterial Enzyme ◽  
Significant Difference

Background and Aim: Candida albicans is a dimorphic fungus that has both yeast and filamentous forms. It is part of the normal flora in the oral and genital areas of mammals. One factor for the pathogenicity of C. albicans is its ability to switch from yeast to hyphae. The hyphal form adheres and penetrates tissues more readily than the yeast form and produces biofilms that are associated with chronic infection. Biofilms are protective niches that enable microorganisms to be more resistant to antibiotic treatment, thus allowing for persistent infection. The first stage in the transition from yeast to hyphae involves the formation of a germ tube, and this transition is triggered by interactions with host cells. Germ tube formation is dependent on serum, pH, temperature, and quorum-sensing molecules (QSMs). Farnesol, which is a QSM in C. albicans, can prevent yeast to hyphae conversion and inhibits the growth of fungal biofilm. Lyticase is a synergistic enzyme complex that catalyzes yeast cell lysis by β-1,3-glucanase and is a highly specific alkaline protease that produces protoplasts or spheroplasts. This study investigated the effect of farnesol and lyticase on the formation of C. albicans biofilms. Materials and Methods: C. albicans ATCC 2091 was cultivated on liquid and solid Sabouraud media. The presence of C. albicans was confirmed using HiCrome Candida Agar chromogenic medium. Enzyme activities were assayed using a HiCandida Identification Kit. The morphology and densitometry parameters of C. albicans biofilms were considered in the presence of farnesol (Sigma-Aldrich, Germany), lyticase (from Arthrobacter luteus; Sigma-Aldrich, Germany), and farnesol–lyticase. Results: This study shows that both farnesol and lyticase possess antifungal activity against C. albicans biofilms. A significant difference among treatment groups (p<0.05) was observed from strong biofilm production to medium and weak. Conclusion: Many studies have been devoted to the antimicrobial action of farnesol. Bacterial enzyme lyticase is also used to degrade fungal cell walls. Both molecules show substantial antifungal properties that are similar to the properties of modern antimycotics. The current study demonstrates that farnesol and lyticase can disrupt biofilm formation in C. albicans ATCC 2091, which is an effective biofilm producer.

An analysis of the metabolism and cell wall composition of Candida albicans during germ-tube formation

1983 ◽  
Vol 29 (11) ◽  
pp. 1514-1525 ◽  
Author(s):  
Patrick A. Sullivan ◽  
Chiew Yoke Yin ◽  
Christopher Molloy ◽  
Matthew D. Templeton ◽  
Maxwell G. Shepherd
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Germ Tube ◽  
Dry Weight ◽  
Tube Formation ◽  
Cell Wall Composition ◽  
Yeast Cells ◽  
Tube Forming ◽  
Insoluble Glucan ◽  
Germ Tubes

The uptake of nutrients (glucose, glutamine, and N-acetylglucosamine), the intracellular concentrations of metabolites (glucose-6-phosphate, cyclic AMP, amino acids, trehalose, and glycogen) and cell wall composition were studied in Candida albicans. These analyses were carried out with exponential-phase, stationary-phase, and starved yeast cells, and during germ-tube formation. Germ tubes formed during a 3-h incubation of starved yeast cells (0.8 × 108 cells/mL) at 37 °C during which time the nutrients glucose plus glutamine or N-acetylglucosamine (2.5 mM of each) were completely utilized. Control incubations with these nutrients at 28 °C did not form germ tubes. Uptake of N-acetylglucosamine and glutamine was inhibited by cycloheximide which suggests that de novo protein synthesis was required for the induction of these uptake systems. The glucose-6-phosphate content varied from 0.4 nmol/mg dry weight for starved cells to 2–3 nmol/mg dry weight for growing yeast cells and germ tube forming cells. Trehalose content varied from 85 nmol/mg dry weight (growing yeast cells and germ tube forming cells) to 165 nmol/mg weight (stationary-phase cells). The glycogen content decreased during germ-tube formation (from 800 to 600 nmol glucose equivalent/mg dry weight) but increased (to 1000 nmol glucose equivalent/mg dry weight) in the control incubation of yeast cells. Cyclic AMP remained constant throughout germ-tube formation at 4–6 pmol/mg dry weight. The total amino acid pool was similar in exponential, starved, and germ tube forming cells but there were changes in the amounts of individual amino acids. The overall cell wall composition of yeast cells and germ tube forming cells were similar: lipid (2%, w/w); protein (3–6%), and carbohydrate (77–85%). The total carbohydrates were accounted for as the following fractions: alkali-soluble glucan (3–8%), mannan (20–23%), acid-soluble glucan (24–27%), and acid-insoluble glucan (18–26%). The relative amounts of the alkali-soluble and insoluble glucan changed during starvation of yeast cells, reinitiation of yeast-phase growth, and germ-tube formation. Analysis of the insoluble glucan fraction from cells labelled with [14C]glucose during germ-tube formation showed that the chitin content of the cell wall increased from 0.6% to 2.7% (w/w).

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