scholarly journals REGULATORY MECHANISMS OF CELLULAR RESPIRATION

1948 ◽  
Vol 32 (2) ◽  
pp. 163-178 ◽  
Author(s):  
E. S. Guzman Barron ◽  
John A. Muntz ◽  
Betty Gasvoda
Keyword(s):  
Cell Metabolism ◽  
Dry Weight ◽  
Lactic Dehydrogenase ◽  
Yeast Cells ◽  
Regulatory Mechanisms ◽  
Cellular Respiration ◽  
Degree Of Dissociation ◽  
E Coli ◽  
Oxidation Of Glucose ◽  
Protein Portion

Uranium as UO2(NO3)2 combines reversibly with proteins. The degree of dissociation of this combination depends, among other factors, on the H+ concentration. At pH 7.3 the U-albumin complex was easily dissociated on addition of citrate, while at pH 3.8 it was not. Uranium inhibited reversibly a number of enzyme systems. Uranium enzyme inhibitions could be reversed on addition of certain hydroxypolycarboxylic acids (citric acid, α-hydroxyaspartic acid, malic acid); in no case, however, did phosphate have any effect. In cell-free yeast juice, the fermentation of glucose-hexosediphosphate was inhibited by UO2(NO3)2. Slight reactivation occurred on addition of phosphate. In living yeast cells, the fermentation and oxidation of glucose was inhibited by small amounts of UO2(NO3)2 (7,7 micrograms per mg. dry weight), while the oxidation of acetic acid, ethyl alcohol, malic and citric acids, was not affected at all. U inhibition in living yeast cells at pH 7.3 was completely released on addition of small amounts of phosphate, adenosinetriphosphate, and citrate, while at pH 3.8 U inhibition was not released by phosphate and citrate. At saturation, one yeast cell contained 7.06 x 106 molecules of uranium. Lactic dehydrogenase was not inhibited by U while the oxidation of lactic acid by gonococci was inhibited. Addition of phosphate released this inhibition. The U inhibition of liver succinoxidase was unaffected by phosphate, while the U inhibition of the oxidation of succinate by E. coli was released by phosphate. It has been concluded from these experiments that U inhibition of cell metabolism is due to combination of the metal with the protein portion of the cell membrane. Uranium is presented as an example of surface inhibition.

Minimization of activated sludge production by chemically stimulated energy spilling

2000 ◽  
Vol 42 (12) ◽  
pp. 189-200 ◽  
Author(s):  
G.-H. Chen ◽  
H.-K. Mo ◽  
S. Saby ◽  
W.-k. Yip ◽  
Y. Liu
Keyword(s):  
Activated Sludge ◽  
Growth Yield ◽  
Dry Weight ◽  
Staining Technique ◽  
Microbial Culture ◽  
Dapi Staining ◽  
E Coli ◽  
Energy Spilling ◽  
Activated Sludge Processes ◽  
Sludge Production

Minimization of excess sludge production in activated sludge processes has been pursued around the world in order to meet stringent environmental regulations on sludge treatment and disposal. To achieve this goal, physical, chemical, and biological approaches have been proposed. In this paper, a chemical compound, 3,3′,4′,5-tetrachlorosalicylanilide (TCS) was tested for enhancing microbial energy spilling of the sludgeso as to minimize its growth. In order to examine this, an exploratory study was conducted using both batch and continuous activated sludge cultures. Batch experiments with these two cultures were carried out at different initial concentrations of TCS. It has been confirmed that an addition of TCS is effective in reducing the production of both the sludge cultures, particularly the continuous culture where the observed growth yield was reduced by around 70%, when the initial TCS concentration was 0.8 ppm. Meanwhile, the substrate removal activity of this culture was found not to be affected at this TCS concentration. To further evaluate the TCS effect, a pure microbial culture of E. coli was employed. Batch experiment results with this culture implied that TCS might be able to reduce the cell density of E. coli drastically when an initial TCS concentration was greater than 0.12 ppm. It was also found that TCS was not toxic to this type of bacteria. Microscopic examinations with a 4′, 6-diamidino-2-phenylindole (DAPI) staining technique revealed that TCS neither affected the cell division nor altered the cell size of E. coli. However, both the cell ATP content and the cell dry weight were reduced significantly with the addition of TCS.

scholarly journals REGULATORY MECHANISMS OF CELLULAR RESPIRATION

1950 ◽  
Vol 34 (2) ◽  
pp. 211-224 ◽  
Author(s):  
E. S. Guzman Barron ◽  
Maria Isabel Ardao ◽  
Marion Hearon
Keyword(s):  
Acetic Acid ◽  
Pyruvic Acid ◽  
No Oxidation ◽  
Yeast Cells ◽  
Acid Formation ◽  
Cellular Respiration ◽  
Acid Oxidase ◽  
Acid Solutions ◽  
Fluoroacetic Acid ◽  
A Cell

The rate of the aerobic metabolism of pyruvic acid by bakers' yeast cells is determined mainly by the amount of undissociated acid present. As a consequence, the greatest rate of oxidation was observed at pH 2.8. Oxidation, at a slow rate, started at pH 1.08; at pH 9.4 there was no oxidation at all. The anaerobic metabolism, only a fraction of the aerobic, was observed only in acid solutions. There was none at pH values higher than 3. Pyruvic acid in the presence of oxygen was oxidized directly to acetic acid; in the absence of oxygen it was metabolized mainly by dismutation to lactic and acetic acids, and CO2. Acetic acid formation was demonstrated on oxidation of pyruvic acid at pH 1.91, and on addition of fluoroacetic acid. Succinic acid formation was shown by addition of malonic acid. These metabolic pathways in a cell so rich in carboxylase may be explained by the arrangement of enzymes within the cell, so that carboxylase is at the center, while pyruvic acid oxidase is located at the periphery. Succinic and citric acids were oxidized only in acid solutions up to pH 4. Malic and α-ketoglutaric acids were not oxidized, undoubtedly because of lack of penetration.

scholarly journals Threonine Overproduction in Yeast Strains Carrying theHOM3-R2 Mutant Allele under the Control of Different Inducible Promoters

1999 ◽  
Vol 65 (1) ◽  
pp. 110-116 ◽  
Author(s):  
María-José Farfán ◽  
Luis Aparicio ◽  
Isabel L. Calderón
Keyword(s):  
Mutant Allele ◽  
Metabolic Flux ◽  
Dry Weight ◽  
Yeast Cells ◽  
Aspartate Kinase ◽  
Inducible Promoters ◽  
Yeast Strains ◽  
Threonine Production ◽  
Amino Acid Contents ◽  
Serine Deaminase

ABSTRACT The HOM3 gene of Saccharomyces cerevisiaecodes for aspartate kinase, which plays a crucial role in the regulation of the metabolic flux that leads to threonine biosynthesis. With the aim of obtaining yeast strains able to overproduce threonine in a controlled way, we have placed the HOM3-R2 mutant allele, which causes expression of a feedback-insensitive enzyme, under the control of four distinctive regulatable yeast promoters, namely, P GAL1 , P CHA1 , P CYC1-HSE2 , and P GPH1 . The amino acid contents of strains bearing the different constructs were analyzed both under repression and induction conditions. Although some differences in overall threonine production were found, a maximum of around 400 nmol/mg (dry weight) was observed. Other factors, such as excretion to the medium and activity of the catabolic threonine/serine deaminase, also affect threonine accumulation. Thus, improvement of threonine productivity by yeast cells would probably require manipulation of these and other factors.

scholarly journals How cells determine the number of polarity sites

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jian-geng Chiou ◽  
Kyle D Moran ◽  
Daniel J Lew
Keyword(s):  
Design Principle ◽  
Fundamental Question ◽  
Yeast Cells ◽  
Regulatory Mechanisms ◽  
Saturation Point ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Theoretical Analyses ◽  
Novel Design ◽  
Insight Into

The diversity of cell morphologies arises, in part, through regulation of cell polarity by Rho-family GTPases. A poorly understood but fundamental question concerns the regulatory mechanisms by which different cells generate different numbers of polarity sites. Mass-conserved activator-substrate (MCAS) models that describe polarity circuits develop multiple initial polarity sites, but then those sites engage in competition, leaving a single winner. Theoretical analyses predicted that competition would slow dramatically as GTPase concentrations at different polarity sites increase towards a 'saturation point', allowing polarity sites to coexist. Here, we test this prediction using budding yeast cells, and confirm that increasing the amount of key polarity proteins results in multiple polarity sites and simultaneous budding. Further, we elucidate a novel design principle whereby cells can switch from competition to equalization among polarity sites. These findings provide insight into how cells with diverse morphologies may determine the number of polarity sites.

Functionalized Polymers as Receptors for Detection of Cells

2011 ◽  
Vol 64 (9) ◽  
pp. 1256 ◽  
Author(s):  
Miroslava Polreichova ◽  
Usman Latif ◽  
Franz L. Dickert
Keyword(s):  
Soft Lithography ◽  
Quartz Crystal ◽  
Coli Strain ◽  
Yeast Cells ◽  
Label Free ◽  
Sensitive Material ◽  
E Coli ◽  
Label Free Detection ◽  
Quartz Crystal Microbalances ◽  
Cell Strains

Mass sensitive sensors were applied for fast and label-free detection of bio-analytes. Robust and miniaturized sensor devices were fabricated by combining bio-mimetic imprinted surfaces with quartz crystal microbalances for the analysis of yeast and bacteria cells. These sensors allow us to differentiate between different growing stages of yeast cells. Moreover, the viability of cells was detected by structuring quartz crystal microbalance electrodes like a grid. Artificial yeast cells were produced to pattern the recognition layer, giving reversible enrichment of the respective bio-analytes. This approach was followed to ensure the reproducibility of the identical sensitive material in each case, because the properties of each cell depend on its growth stage, which varies over time. The strategy was further applied to develop a sensitive system for Escherichia coli. Structuring of these materials by soft lithography allows differentiation between cell strains, e.g. E. coli (strain W & B) with a five-fold selectivity.

scholarly journals Metabolic cost of rapid adaptation of single yeast cells

2020 ◽  
Vol 117 (20) ◽  
pp. 10660-10666 ◽  
Author(s):  
Gabrielle Woronoff ◽  
Philippe Nghe ◽  
Jean Baudry ◽  
Laurent Boitard ◽  
Erez Braun ◽  
...  
Keyword(s):  
Cell Metabolism ◽  
Single Cells ◽  
A Priori ◽  
Metabolic Cost ◽  
Microfluidic System ◽  
Cellular Reprogramming ◽  
Yeast Cells ◽  
Rapid Adaptation ◽  
Metabolic Coupling ◽  
Induced Changes

Cells can rapidly adapt to changing environments through nongenetic processes; however, the metabolic cost of such adaptation has never been considered. Here we demonstrate metabolic coupling in a remarkable, rapid adaptation process (1 in 1,000 cells adapt per hour) by simultaneously measuring metabolism and division of thousands of individual Saccharomyces cerevisiae cells using a droplet microfluidic system: droplets containing single cells are immobilized in a two-dimensional (2D) array, with osmotically induced changes in droplet volume being used to measure cell metabolism, while simultaneously imaging the cells to measure division. Following a severe challenge, most cells, while not dividing, continue to metabolize, displaying a remarkably wide diversity of metabolic trajectories from which adaptation events can be anticipated. Adaptation requires a characteristic amount of energy, indicating that it is an active process. The demonstration that metabolic trajectories predict a priori adaptation events provides evidence of tight energetic coupling between metabolism and regulatory reorganization in adaptation. This process allows S. cerevisiae to adapt on a physiological timescale, but related phenomena may also be important in other processes, such as cellular differentiation, cellular reprogramming, and the emergence of drug resistance in cancer.

scholarly journals Evaluation of the Oxidative Stress Response of Aging Yeast Cells in Response to Internalization of Fluorescent Nanodiamond Biosensors

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 372
Author(s):  
Kiran J. van der Laan ◽  
Aryan Morita ◽  
Felipe P. Perona-Martinez ◽  
Romana Schirhagl
Keyword(s):  
Oxidative Stress ◽  
Free Radicals ◽  
Free Radical ◽  
Stress Response ◽  
Cell Metabolism ◽  
High Reactivity ◽  
Magnetic Sensors ◽  
Yeast Cells ◽  
Stress Effects ◽  
Related Stress

Fluorescent nanodiamonds (FNDs) are proposed to be used as free radical biosensors, as they function as magnetic sensors, changing their optical properties depending on their magnetic surroundings. Free radicals are produced during natural cell metabolism, but when the natural balance is disturbed, they are also associated with diseases and aging. Sensitive methods to detect free radicals are challenging, due to their high reactivity and transiency, providing the need for new biosensors such as FNDs. Here we have studied in detail the stress response of an aging model system, yeast cells, upon FND internalization to assess whether one can safely use this biosensor in the desired model. This was done by measuring metabolic activity, the activity of genes involved in different steps and the locations of the oxidative stress defense systems and general free radical activity. Only minimal, transient FND-related stress effects were observed, highlighting excellent biocompatibility in the long term. This is a crucial milestone towards the applicability of FNDs as biosensors in free radical research.

scholarly journals Biosynthesis of Coenzyme Q in the Phytopathogen Xanthomonas campestris via a Yeast-Like Pathway

2019 ◽  
Vol 32 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Lian Zhou ◽  
Ming Li ◽  
Xing-Yu Wang ◽  
Hao Liu ◽  
Shuang Sun ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Coenzyme Q ◽  
Regulatory Mechanisms ◽  
Membrane Component ◽  
E Coli ◽  
Regulatory Complex ◽  
Iron Carboxylate ◽  
Xanthomonas Campestris Pv Campestris ◽  
Specific Inhibitors ◽  
Novel Protein

Coenzyme Q (CoQ) is a lipid-soluble membrane component found in organisms ranging from bacteria to mammals. The biosynthesis of CoQ has been intensively studied in Escherichia coli, where 12 genes (ubiA, -B, -C, -D, -E, -F, -G, -H, -I, -J, -K, and -X) are involved. In this study, we first investigated the putative genes for CoQ8 biosynthesis in the phytopathogen Xanthomonas campestris pv. campestris using a combination of bioinformatic, genetic, and biochemical methods. We showed that Xc_0489 (coq7Xc) encodes a di-iron carboxylate monooxygenase filling the E. coli UbiF role for hydroxylation at C-6 of the aromatic ring. Xc_0233 (ubiJXc) encodes a novel protein with an E. coli UbiJ-like domain organization and is required for CoQ8 biosynthesis. The X. campestris pv. campestris decarboxylase gene remains unidentified. Further functional analysis showed that ubiB and ubiK homologs ubiBXc and ubiKXc are required for CoQ8 biosynthesis in X. campestris pv. campestris. Deletion of ubiJXc, ubiBXc, and ubiKXc led to the accumulation of an intermediate 3-octaprenyl-4-hydroxybenzoic acid. UbiKXc interacts with UbiJXc and UbiBXc to form a regulatory complex. Deletion analyses of these CoQ8 biosynthetic genes indicated that they are important for virulence in Chinese radish. These results suggest that the X. campestris pv. campestris CoQ8 biosynthetic reactions and regulatory mechanisms are divergent from those of E. coli. The variations provide an opportunity for the design of highly specific inhibitors for the prevention of infection by the phytopathogen X. campestris pv. campestris.

Selective induction and suppression of liver enzyme synthesis

1962 ◽  
Vol 202 (1) ◽  
pp. 137-144 ◽  
Author(s):  
George Weber ◽  
Gouri Banerjee ◽  
Seymour B. Bronstein
Keyword(s):  
Enzyme Activities ◽  
Lactic Dehydrogenase ◽  
Enzyme Synthesis ◽  
Direct Oxidation ◽  
Phosphohexose Isomerase ◽  
Phosphogluconate Dehydrogenase ◽  
Acid Analogue ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Oxidation Of Glucose

Two techniques were used to demonstrate selective induction of enzyme increases in mammalian tissue in vivo: a) refeeding of fasted animals, and b) administration of cortisone to adrenalectomized animals. Refeeding acted selectively as an inducer for the stimulation of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities, and as a less effective inducer of phosphoglucomutase, phosphohexose isomerase, glucose-6-phosphatase, and lactic dehydrogenase. On the other hand, cortisone acted selectively as an inducer for increases in glucose-6-phosphatase, fructose-1, 6-diphosphatase, phosphohexose isomerase and lactic dehydrogenase, and as a less effective inducer of 6-phosphogluconate dehydrogenase. Thus, refeeding primarily stimulated enzymes mediating the direct oxidation of glucose-6-phosphate, whereas cortisone stimulated enzymes involved in gluconeogenesis. The amino acid analogue ethionine selectively inhibited the induced increase of enzyme activities and methionine reversed the ethionine inhibition. The nature of the elevations in the enzyme activities and the mechanisms of ethionine inhibition were discussed.

scholarly journals Accumulation of Selenium in Candida utilis Growing in Media of Increasing Concentration of this Element

2020 ◽  
Vol 10 (4) ◽  
pp. 1439 ◽  
Author(s):  
Marek Kieliszek ◽  
Anna Maria Kot ◽  
Kamil Piwowarek ◽  
Stanisław Błażejak
Keyword(s):  
Candida Utilis ◽  
Culture Medium ◽  
Dry Weight ◽  
Yeast Cells ◽  
Reciprocating Motion ◽  
Experimental Medium ◽  
Yeast Cultures ◽  
Cell Biomass ◽  
Icp Ms ◽  
Living Organisms

Selenium is considered an essential component of all living organisms. Studies on the enrichment of yeast cells with selenium, using the ability of cell biomass to bind this element, are being reported more and more. Yeast cultures were cultivated in YPD medium enriched with Na2SeO3 salts for 72 h at 28 °C on a shaker utilizing reciprocating motion. Selenium in cell biomass was determined with the use of ICP–MS. It was observed that the addition of selenium to the experimental medium (in the range of 4–100 mg/L) increased the content of this element in the yeast cell biomass. During the extension of cultivation time, the number of yeast cells and biomass yield exhibited a decreasing trend. Based on the obtained results, it was concluded that yeast cells exhibited the ability to accumulate selenium in both logarithmic and stationary growth phases. The dose of 20 and 30 mg/L of selenium in the culture medium meets the expectations in terms of both the content of selenium bound to yeast cells (1944 ± 110.8 μg/g dry weight) under 48-h cultivation. The obtained results confirmed that the Candida utilis ATCC 9950 strain exhibits the ability to bind selenium, which means that the biomass of these yeasts may be used as a natural source of selenium in the diet of humans and animals.

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