Endocytosis and vacuolar morphology inSaccharomyces cerevisiae are altered in response to ethanol stress or heat shock

Meaden, Philip G.; Arneborg, Nils; Guldfeldt, Lars Uhre; Siegumfeldt, Henrik; Jakobsen, Mogens

doi:10.1002/(sici)1097-0061(19990915)15:12<1211::aid-yea448>3.0.co;2-h

Cited by 54 publications

(43 citation statements)

References 35 publications

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“…5). The axl2⌬ staining pattern is reminiscent of what has been observed in endocytic mutant S. cerevisiae and in S. cerevisiae exposed to ethanol and heat stress (59,91). Additionally, a similar phenotype for FM4-64 uptake has been reported for an Ashbya mutant lacking Wal1 that also has altered actin patch localization (86).…”

supporting

confidence: 74%

“…5). Wild-type hyphae displayed what is likely vacuolar, endosome, and plasma membrane staining, while axl2⌬ hyphae displayed much smaller cortical intermediates, similar to those seen in S. cerevisiae deleted for the endocytic proteins ScShe4, ScPan1, and ScEnd3 or subjected to ethanol stress or heat shock (59,91). Therefore, defective patch polarity may be leading to inefficient endocytosis which leads to defects in polarity maintenance in axl2⌬ cells.…”

Section: Resultsmentioning

confidence: 72%

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Axl2 Integrates Polarity Establishment, Maintenance, and Environmental Stress Response in the Filamentous Fungus Ashbya gossypii

Anker

Gladfelter

2011

Eukaryot Cell

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In budding yeast, new sites of polarity are chosen with each cell cycle and polarization is transient. In filamentous fungi, sites of polarity persist for extended periods of growth and new polarity sites can be established while existing sites are maintained. How the polarity establishment machinery functions in these distinct growth forms found in fungi is still not well understood. We have examined the function of Axl2, a transmembrane bud site selection protein discovered in Saccharomyces cerevisiae, in the filamentous fungus Ashbya gossypii. A. gossypii does not divide by budding and instead exhibits persistent highly polarized growth, and multiple axes of polarity coexist in one cell. A. gossypii axl2⌬ (Agaxl2⌬) cells have wavy hyphae, bulbous tips, and a high frequency of branch initiations that fail to elongate, indicative of a polarity maintenance defect. Mutant colonies also have significantly lower radial growth and hyphal tip elongation speeds than wild-type colonies, and Agaxl2⌬ hyphae have depolarized actin patches. Consistent with a function in polarity, AgAxl2 localizes to hyphal tips, branches, and septin rings. Unlike S. cerevisiae Axl2, AgAxl2 contains a Mid2 homology domain and may function to sense or respond to environmental stress. In support of this idea, hyphae lacking AgAxl2 also display hypersensitivity to heat, osmotic, and cell wall stresses. Axl2 serves to integrate polarity establishment, polarity maintenance, and environmental stress response for optimal polarized growth in A. gossypii.The establishment and maintenance of cell polarity are essential for proper cell morphology and growth in both unicellular and multicellular eukaryotes (25, 39). Directional growth, neuronal development and function, membrane trafficking in epithelial cells, and whole-cell motility by chemotaxis all rely on the generation of cell polarity (5, 88, 97). Polar growth has been linked to fungal virulence in human pathogens such as Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, and Paracoccidioides brasiliensis (3,6,67,80). Many mechanisms governing cell polarity and polarized growth were discovered in the budding yeast, Saccharomyces cerevisiae, and are highly conserved from unicellular eukaryotes to humans (62).In S. cerevisiae, budding can occur in either an axial or a bipolar manner, which is determined by specific landmark proteins. The axial landmark consists of the septin complex, S. cerevisiae Bud3 (ScBud3), ScBud4, ScAxl1, and ScAxl2 and functions by recruiting members of the Cdc42 signaling pathway (1,14,30,31,38,44,45,69,72,98). The localization and activation of Cdc42 at sites specified by the landmarks then direct bud formation through polarization of the actin cytoskeleton (2, 99). Polarized actin cables form tracks on which myosins transport secretory vesicles to the growing bud (11,29,37). Polarized cortical actin patches are sites of endocytosis and as such can function to internalize any polarity factors that diffuse beyond the region of polarized growth (36,57,61).ScA...

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supporting

confidence: 74%

Section: Resultsmentioning

confidence: 72%

Axl2 Integrates Polarity Establishment, Maintenance, and Environmental Stress Response in the Filamentous Fungus Ashbya gossypii

Anker

Gladfelter

2011

Eukaryot Cell

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“…A schematic diagram of the chamber has been published previously (21). Solutions were perfused through the inlet of the chamber at a rate of 8.3 l s Ϫ1 by using a modified Alitea-XV pump (Microlab Aarhus A/S, Aarhus, Denmark).…”

Section: Methodsmentioning

confidence: 99%

Dynamic Changes of Intracellular pH in Individual Lactic Acid Bacterium Cells in Response to a Rapid Drop in Extracellular pH

Siegumfeldt

Rechinger

Jakobsen

2000

Appl Environ Microbiol

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141

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We describe the dynamics of changes in the intracellular pH (pH i ) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular pH (pH ex ). Strains of Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Lactococcus lactis were investigated. Listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. The method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possible to describe variations in pH i within a population. The bacteria were immobilized on a membrane filter, placed in a closed perfusion chamber, and analyzed during a rapid decrease in the pH ex from 7.0 to 5.0. Under these conditions, the pH i of L. innocua remained neutral (between 7 and 8). In contrast, the pH i values of all of the strains of lactic acid bacteria investigated decreased to approximately 5.5 as the pH ex was decreased. No pronounced differences were observed between cells of the same strain harvested from the exponential and stationary phases. Small differences between species were observed with regard to the initial pH i at pH ex 7.0, while different kinetics of pH i regulation were observed in different species and also in different strains of S. thermophilus.Bacteria have developed different ways to withstand stressful situations, such as a decrease in the pH ex . Neutrophilic bacteria like Escherichia coli maintain a pH i that is close to neutral when the pH ex is decreased and therefore generate large proton gradients (28). Among the gram-positive bacteria, strains of Enterococcus hirae which were originally identified as Streptococcus faecalis (12) have been studied extensively in order to examine pH homeostasis (14-16). These bacteria also grow at alkaline pH values, and they are considered neutrophiles (31), although they are phylogenetically related to streptococci and lactococci.Many acid-tolerant fermentative bacteria have developed another strategy; in these organisms the pH i decreases as the pH ex decreases during growth (4, 23) in order to maintain a constant pH gradient rather than a constant pH i . Generating a large proton gradient is disadvantageous for fermentative lactic acid bacteria, because proton translocation consumes energy (16), and anaerobic organisms gain significantly less energy from sugar metabolism than aerobes gain. Furthermore, a large proton gradient results in accumulation of organic acid anions in the cytosol (33).Food fermentations are often carried out by sequential microbial populations; this occurs in dairy fermentations, such as yogurt fermentation (32), as well as in indigenous spontaneous fermentations of cereals and vegetables (7,10,20). Lactic acid bacteria, particularly lactobacilli, which are considered the most acid-tolerant bacteria, are often dominant at the end of these fermentations (13, 34). The acid tolerance of these organisms is advantageous, as they have a competitive advantage over known pathogens and other undesirable bacteria when the concent...

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“…Ethanol affects many aspects of yeast survival, as the fluidity of the plasmatic membrane [35], the vacuole morphology [36], the activity of crucial glycolytic enzymes [37], and the mitochondrial DNA [38]. Ethanol also causes the denaturation of hydrophilic and hydrophobic proteins, affecting various transport systems such as the general amino acid permease and glucose uptake processes [18].…”

Section: Ethanolmentioning

confidence: 99%

Growth Kinetics for the Selection of Yeast Strains for Fermented Beverages

Miranda-Castilleja¹,

Tapia²,

Arvizu-Medrano³

et al. 2017

Yeast - Industrial Applications

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Criteria to select autochthonous yeast strains for their use in fermented beverages include their ability to dominate the media and to enhance desired sensorial characteristics and their inability to produce undesired compounds such as biogenic amines or off-odors. One of the key features in yeast selection is its Implantation, surpassing different stresses, and its fermentation performance, which requires setting up the process and monitoring it, involving important amount of resources. Methods to evaluate the tolerance of yeast strains are usually based in the qualitative measure of the growth of the microorganism in a medium containing the limiting compound after a specific time of incubation. However, studying strain growth through optical density measurements permits to estimate quantitative and comparable parameters providing an insight into the fitness of the cell to certain environment, lag phase duration, growth rate, and maximum population, among others. In the last decades, cultureindependent methods have been used to evaluate the dynamic of microbial populations during fermentative process. In this chapter, a review of recent advances in the selection of fermentative yeasts as well as the utilization of kinetic evaluation and molecular strategies in conditions associated with fermented beverage for selecting yeast strains is presented.

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Endocytosis and vacuolar morphology inSaccharomyces cerevisiae are altered in response to ethanol stress or heat shock

Cited by 54 publications

References 35 publications

Axl2 Integrates Polarity Establishment, Maintenance, and Environmental Stress Response in the Filamentous Fungus Ashbya gossypii

Axl2 Integrates Polarity Establishment, Maintenance, and Environmental Stress Response in the Filamentous Fungus Ashbya gossypii

Dynamic Changes of Intracellular pH in Individual Lactic Acid Bacterium Cells in Response to a Rapid Drop in Extracellular pH

Growth Kinetics for the Selection of Yeast Strains for Fermented Beverages

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