Showing papers on "Yeast published in 1974"
TL;DR: Two features which distinguish the cell cycle of Saccharomyces cerevisiae from most other eukaryotes are particularly useful for an analysis of the gene functions that control the cell division cycle.
Abstract: Mitotic cell division in eukaryotes is accomplished through a highly reproducible temporal sequence of events that is common to almost all higher organisms. An interval of time, Gl, separates the previous cell division from the initiation of DNA synthesis. Ohromosome replication is acco’mplished during the DNA synthetic period, S, which typically occupies about a third of the cell cycle. Another interval of time, G2, separates the completion of DNA synthesis from prophase, the beginning of mitosis, M. A dramatic sequence of changes in chromosome structure and of chromosome ,movement characterizes the brief mitotic period that results in the precise separation of sister chromatids to daughter nuclei. Mitosis is followed by cytokinesis, the partitioning of the cytoplasm into two daughter cells with separate plasma membranes. In some organisms the cycle is completed by cell wall separation. Each of these events occurs during the cell division cycle of the yeast, Saccharomyces cerevisiae (I) (Fig. 1) . However, two features which distinguish the cell cycle of S. cerevisiae from most other eukaryotes are particularly useful for an analysis of the gene functions that control the cell division cycle. First, the fact that both haploid and diploid cells undergo mitosis permits the isolation of recessive mutations in haploids and their analysis by complementation in diploids. Second, the daughter cell is recognizable at an early stage of the cell cycle as a bud on the surface of the parent cell. Since the ratio of bud size to parent cell size increases progressively during the cycle, this ratio pro-
1,683 citations
TL;DR: Examination of the survival responses of multiple-mutant strains indicated a minimum of two pathways in the repair of X-ray damage, and a number of the mutants have been mapped and these were found to be dispersed over the genome.
Abstract: A set of 64 mutants of Saccharomyces cerevisiae that confer sensitivity to X-ray inactivation were analyzed genetically to determine the number of genetic loci involved. The mode of interaction of various combinations of mutants was also determined. A minimum of 17 genes, when mutant, increase X-ray sensitivity of yeast, primarily by eliminating the resistance of budding haploid cells and by removing the shoulder on the survival curves of diploid cells. Eight mutant loci affect principally X-ray sensitivity while the remaining genes also control sensitivity to ultraviolet. Some of the genes when homozygous block sporulation or result in partial or complete sterility. Examination of the survival responses of multiple-mutant strains indicated a minimum of two pathways in the repair of X-ray damage. A number of the mutants have been mapped and these were found to be dispersed over the genome.
469 citations
TL;DR: In yeast tunicamycin acts primarily as an inhibitor of glycoprotein synthesis and not of general glucosamine metabolism, and incorporation of 3H-glucosamine into trichloroacetic acid-insoluble products was only partially reduced.
274 citations
TL;DR: There is chemical, cytochemical and ultrastructural evidence that the differences between Y and M walls of C. albicans are essentially quantitative, strongly suggesting that hyphal conversion in this yeast is controlled by the modulation of pre-existing enzymatic activities rather than by any new factors.
Abstract: DIMORPHISM in fungi is generally defined as a reversible transition from a yeast habit of growth (Y) to a mycelial one (M)1. In Candida albicans Y→M transition can occur rapidly in serum2,3, serum substitutes and other natural4–6 and synthetic media7. In a few hours the yeast cell or blastospore forms a germ tube which grows as a true mycelium6,8,9. Since the cellular form depends on wall construction10, marked modifications in the organisation of wall components are expected to, and in fact do, occur during morphogenesis. Nevertheless, there is chemical11, cytochemical and ultrastructural evidence12,13 that the differences between Y and M walls of C. albicans are essentially quantitative, strongly suggesting that hyphal conversion in this yeast is controlled by the modulation of pre-existing enzymatic activities rather than by any new factors.
216 citations
TL;DR: Cell free extracts prepared from resting yeast were shown to contain a cryptic trehalase, which under physiological conditions could be activated by cyclic 3′,5′-AMP to the same degree as in vivo, suggesting that in the lag phase of growth, the level of trehalose in baker's yeast is under control of a system, regulated by thelevel of cyclic 2′,3′,4″-AMP.
202 citations
TL;DR: It was found that culture conditions which either induce biochemical differentiation of cells or which do not allow growth result in the enhancement of proteolytic activities, suggesting that their function is primarily the intravacuolar digestion of proteins.
126 citations
TL;DR: Cell fractionation experiments utilizing strains of the latter type have shown that the dsRNA is associated with isometric virus-like particles similar to those found in other fungi.
Abstract: Summary
Two high mol. wt. double stranded RNA species have been discovered in yeast; some strains possess both species (killers) whilst other strains possess only one. Strains of the latter type have been isolated which possess relatively large amounts of dsRNA. Cell fractionation experiments utilizing these strains have shown that the dsRNA is associated with isometric virus-like particles similar to those found in other fungi. Similar particles, containing both species of dsRNA, have been isolated from a killer strain. The two species of dsRNA appear to be separately encapsidated.
117 citations
TL;DR: Density gradient centrifugation and the behavior of marker enzymes suggest that all of the above enzymes of the isoleucine-valine biosynthetic pathway are associated with the mitochondria.
Abstract: By using the method of stepwise homogenization of yeast spheroplast lysates employed previously with the leucine biosynthetic enzymes, it is shown that threonine deaminase, acetohydroxy acid synthase, Mg2+-dependent isomero-reductase, and dihydroxy acid dehydratase are particulate. Density gradient centrifugation and the behavior of marker enzymes suggest that all of the above enzymes of the isoleucine-valine biosynthetic pathway are associated with the mitochondria.
114 citations
TL;DR: Adenosine 3' : 5'-monophosphate (cyclic AMP)-dependent protein kinase which catalyzes the phosphorylation of histone and protamine is purified about 100-fold from the soluble fraction of bakers' yeast by streptomycin treatment, ammonium sulfate fractionation, followed by DEAE-cellulose column chromatography and isoelectrofocusing electrophoresis.
105 citations
104 citations
TL;DR: Two protein inhibitors of the tryptophan synthase inactivating yeast proteinase B were purified from boiled bakers' yeast extract and are very stable in the pH range of 1 to 10, but they are easily destroyed by incubation with proteinase A and, less effectively, withproteinase B.
TL;DR: The isolation and subsequent chemical analysis of lipid particles from baker’s yeast show that triacylglycerols and sterol esters are the major components of the lipid and account for 90-95% of the total particle content.
TL;DR: Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast, including the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism.
Abstract: Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast. One such factor was the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism. In such cases (lactose and glycerol), the sugar-tolerant species had a much lower capacity for the solute than did the nontolerant species. Sucrose uptake was consistently different between all sugar-tolerant strains on the one hand and all nontolerant strains on the other. The difference was attributable in part to metabolism of sucrose by the nontolerant yeasts. The major difference between the two types of yeast, however, was the presence of one or more polyhydric alcohols at high concentrations within each of the sugar-tolerant strains but none of the nontolerant strains. In most cases the major polyol was arabitol. The solute concentration (and, hence, water availability) of the growth medium affected both the amount of arabitol produced by Saccharomyces rouxii and the proportion retained by the yeast after brief washing with water at 0 C. When the yeast was suspended in a buffer at 30 C, the polyol leaked out at a slow, constant, reproducible rate. The polyene antibiotic amphotericin B caused rapid release of polyol by the yeast, the rate being proportional to amphotericin concentration. Contact of the yeast with glucose (1 mM) caused an extremely rapid ejection of polyol which lasted less than 40 s. Some implications of these results are discussed, as is the role of the polyol as a compatible solute in determining the water relations of the yeast.
Journal Article•
TL;DR: In this article, the authors present knowledge of sulfite and sulfide formation by wine yeasts during the fermentation of grape juice and discuss possible sources of sulfur, namely sulfate, sulfite, elemental sulfur and sulfur-containing amino acids.
Abstract: Present knowledge of sulfite and sulfide formation by wine yeasts during the fermentation of grape juice is reviewed. Possible sources of sulfur, namely sulfate, sulfite, elemental sulfur and sulfur-containing amino acids, are discussed. Factors influencing sulfide as well as sulfite formation are emphasized. Low-sulfite and high-sulfite-forming yeast strains differ in their metabolism as well as in some aspects of regulation.
TL;DR: Both inhibitors were inactivated after incubation with purified yeast proteinase B, but not with the yeast proteinases A or C, and the inhibition of proteinase A at high inhibitor/proteinase ratios was more pronounced at pH 5 and 7 as compared to pH 3.5 and 7.
Abstract: Inhibitors for yeast proteinase A have been purified from boiled extracts from baker's yeast. Upon SP-Sephadex C-25 column chromatography, four different peaks of proteinase A inhibitory activity appear. The inhibitors IA2 and IA3 have been further purified by QAE-Sephadex chromatography and preparative disc electrophoresis. Both inhibitors are homogeneous in dodecylsulfate-gel electrophoresis. From the electrophoretic mobilities in dodecylsulfate-polyacrylamide gels, a molecular weight of 6100 ± 200 was estimated for both inhibitors. In the absence of dodecylsulfate, both inhibitors showed one predominant band and a second faint, diffuse band. As a result of Sephadex G-75 gel filtration, a molecular weight of 23000 ± 2000 was obtained for both inhibitors, indicating an aggregation of the monomers to a tetramer. Upon electrofocusing in acrylamide gels the isoelectric points of the inhibitors were found to be 5.7 for IA2 and 6.3 for IA3. Both inhibitors inhibited proteinase A. Neither proteinases B and C from yeast nor pepsin were inhibited. Both inhibitors were inactivated after incubation with purified yeast proteinase B, but not with the yeast proteinases A or C. The inhibition of proteinase A at high inhibitor/proteinase ratios was more pronounced at pH 5 and 7 as compared to pH 3. An autocatalytic activation of a mixture of inhibited proteinases A, B and C by addition or liberation of traces of active proteinase A or B is discussed.
TL;DR: In this paper, the authors studied the effects of fermenting wort of unusually high specific gravity, followed by dilution with water to give beer of normal original gravity, but matching of flavors requires control of the level of flavour determinants.
Abstract: Some effects have been studied of fermenting wort of unusually high specific gravity, followed by dilution with water to give beer of normal original gravity. This procedure permits increased overall rates of beer production, but matching of flavours requires control of the level of flavour determinants. If not controlled, the concentration of volatile esters may be disproportionately increased so that, after dilution, beer flavour is markedly different. Higher alcohol production is not affected in this way. The concentration of esters can be adjusted to appropriate levels by increasing the production of yeast mass during fermentation. Unsaturated fatty acids, which increase yeast dry matter production without altering the rate of fermentation, are particularly effective in reducing the extent of ester synthesis.
TL;DR: Recent progress is described in the characterization of spo mutants of ten loci and three dominant mutants which demonstrate features of the integration and coordinate control of certain landmark events of meiosis and spore formation in yeast.
Abstract: PORULATION of diploids of Saccharomyces cerevisiae involves meiosis and subsequent ascospore formation. The genetic and physiological control of this process is of interest as a model system for the control of meiosis and gametogenesis and has been the subject of several reviews (FOWELL 1969; HABER and HALVORSON 1972; TINGLE et al. 1973). Study of meiosis and gamete formation at the biochemical, genetic, and cytological levels in several organisms has yielded a wealth of information. However, we still have relatively little knowledge of the nature and number of independent gene functions which control the events we observe and integrate them into a successful developmental sequence. Our primary objective has been to dissect the genetic control of meiosis and sporulation in yeast through the study of variants, mutant in gene functions indispensible for the completion of sporulation but which are capable of growth by mitosis and budding. We have thus attempted to restrict our attention to the properties of mutants defective in functions specific to meiosis and ascospore development. Both recessive (spo) and dominant (WO) temperature-sensitive sporulation-deficient mutants have been isolated and eleven loci have been identified among recessive spo mutants (ESPOSITO and ESPOSITO 1969; and ESPOSITO et al. 1972). Complementation studies suggest that approximately 50 loci coding functions indispensible for sporulation may be recovered (ESPOSITO et al. 1972). In this report we wish to describe recent progress in the characterization of spo mutants of ten loci and three dominant mutants. These studies provide information with respect to the stages of sporulation where development may terminate or become abnormal among mutants which fail to form typical ascospores at a restrictive temperature. Sporulation-deficient mutants of three loci (spol, sp02, and spo3) have been examined for both recombinational ability (ESPOSITO and ESPOSITO 1974) and fine structural development at the level of electron microscopy (MOENS, ESPOSITO and ESPOSITO 1974). These mutants demonstrate features of the integration and coordinate control of certain landmark events of meiosis and spore formation in yeast.
TL;DR: Only small numbers of fungi were found in the rumen fluid of cattle cultured on agar plates at 39°C, the counts being up to 3500 yeast colonies/ml, with a similar number of mould colonies, but considerably larger numbers of yeast colonies appeared on plates incubated at 25°C.
Abstract: Summary: Only small numbers of fungi were found in the rumen fluid of cattle cultured on agar plates at 39°C, the counts being up to 3500 yeast colonies/ml, with a similar number of mould colonies. However, considerably larger numbers of yeast colonies appeared on plates incubated at 25°C. Nine species of yeasts were isolated belonging to Candida (including corresponding species of Pichia), Trichosporon, Torulopsis, Kluyveromyces, Saccharomycopsis, and Hansenula. The predominating species were Candida krusei, Trichosporon cutaneum and Trichosporon capitatum. The most common moulds were members of the Mucoraceae, of which Absidia corymbifera, A. ramosa, and Mucor pusillus were identified. Aspergillus fumigatus was isolated frequently. The fungal content of rumen fluid seemed to be dependent on the diet of the animal, and no particular fungal flora could be associated with the rumen per se. The predominating Candida krusei, and also the rarely-isolated species Torulopsis pintolopesii and Kluyveromyces bulgaricus, could reproduce under anaerobic conditions in vitro, but another commonly occurring yeast, Trichosporon capitatum, was unable to grow under the same conditions. The majority of yeast cells were obviously destroyed during passage through the alimentary tract, whereas large quantities of moulds could be excreted in a viable state.
TL;DR: The role of oxygen in yeast metabolism in brewery fermentation is surveyed and variations in oxygen availability, by modifying yeast activity, can affect beer flavour.
Abstract: In suitable circumstances, yeast activity during brewery fermentation may be controlled by regulation of the supply of oxygen. Yeasts can be divided into four classes depending on their susceptibility to such control. Propagation methods and wort composition influence the magnitude of the requirements for oxygen. Variation in oxygen availability, by modifying yeast activity, can affect beer flavour. The role of oxygen in yeast metabolism in brewery fermentation is surveyed.
TL;DR: Maltase, phosphatase, malate dehydrogenase, glucose‐6‐phosphate dehydrogensase, and 6-phosphogluconate dehydration activities were determined in the supernatant of brewer's yeast cells from samples taken at various intervals during a 90 min treatment in a Dyno‐Mill disintegrator.
Abstract: Maltase, phosphatase, malate dehydrogenase, glucose‐6‐phosphate dehydrogenase, and 6‐phosphogluconate dehydrogenase activities were determined in the supernatant of brewer's yeast cells from samples taken at various intervals during a 90 min treatment in a Dyno‐Mill disintegrator.
TL;DR: Results obtained in experiments of interactions between yeast whole histones ans calf thymus DNA also confirm the absence of a very lysine-rich histone in yeast.
Abstract: 1
Baker's yeast histones have been isolated either by acid extraction of purified chromatin or by salt-dissociation of crude chromatin. These two methods gave similar results as judged by the amino-acid composition and electrophoretic behaviour of histones.
2
Chemical fractionation methods have been used to isolate both, moderately lysine-rich and arginine-rich histones. Neither F1 nor F3 histones could be detected in yeast chromatin throughout these fractionation procedures. Results obtained in experiments of interactions between yeast whole histones ans calf thymus DNA also confirm the absence of a very lysine-rich histone in yeast.
3
The fractionation of arginine-rich histones was achieved by selective precipitation with acetone. F2A1 and F2A2 histones were obtained, purified and characterised by electrophoresis and amino acid analyses. The similarities between yeast and other organisms histone fractions are discussed.
TL;DR: Peptides containing COOH-terminal methionine residues were observed to be better growth substrates than those peptides having different amino acid residues at this position, and the ability of both organisms to utilize similar peptide substrates is different.
TL;DR: The number of proteins in yeast ribosomal subunits was determined by two-dimensional polyacrylamide gel electrophoresis and four extra protein spots appeared in the electropherograms of both 40S and 60S subunits.
Abstract: The number of proteins in yeast ribosomal subunits was determined by two-dimensional polyacrylamide gel electrophoresis. The 40S subunit obtained after dissociation of ribosomes at high ionic strength contains 30 different protein species (including six acidic proteins). The 60S subunit, obtained in the same way contains 39 different species (including 1 acidic protein). While the total number of protein species found in yeast ribosomes, thus, is in close agreement with those reported for other eukaryotic organisms, the distribution between acidic and basic proteins is quite different.
TL;DR: It is suggested that the resistance to sphaeroplast formation characteristic of stationary-phase yeasts is the result of a specific modification of the yeasts during the transition period which is dependent on both RNA and protein synthesis.
Abstract: SUMMARY: The sensitivity of Saccharomyces cerevisiae to sphaeroplast formation has been examined during the transition from the exponential phase of growth to the stationary phase. Exponential-phase yeasts are sensitive to sphaeroplast formation while stationary yeasts are resistant. During the transition period, there is a rapid increase in resistance to sphaeroplast formation. This increase can be inhibited by treatment with either cycloheximide or 5-fluorouracil. It is suggested that the resistance to sphaeroplast formation characteristic of stationary-phase yeasts is the result of a specific modification of the yeasts during the transition period which is dependent on both RNA and protein synthesis.
TL;DR: The experimental results indicate that, in addition to membrane lipids, vicinal water may be involved in this phase transition in active dry yeast reconstituted in water at 38–42°C.
TL;DR: The acid content of a range of ales and lagers has been measured for some organic acids related to the Krebs cycle, and found to vary widely, suggesting that yeast converts pyruvate to acetate towards the end of fermentation.
Abstract: The acid content of a range of ales and lagers has been measured for some organic acids related to the Krebs cycle, and found to vary widely. Acetate, pyruvate, lactate, succinate, pyroglutamate, malate and citrate were present in all cases and α-ketoglutarate was usually detected. α-Hydroxyglutarate was recognized in a number of beers. The effect of the acids on the pH of beer is assessed. The strain of yeast which is used markedly influences the levels of all acids except pyroglutamate and the conditions of yeast propagation have a substantial influence on the extent of acid accumulation. During the fermentation of wort and synthetic media the extent of organic acid excretion is proportional to the extent of fermentation, but the nature of the acids which are excreted varies during the fermentation period. In synthetic media, nitrogen source is shown to have a substantial effect on the accumulation of organic acid. Pyruvate and acetate levels vary inversely towards the end of fermentation, suggesting that yeast converts pyruvate to acetate.
TL;DR: The proteinases of a freshly prepared vacuole fraction from yeast spheroplasts are unable to inactivate externally added tryptophan synthase unless the organelles are disrupted by sonication or osmotic shock.
Abstract: Ficoll-gradient fractionation of a metabolic lysate from yeast spheroplasts was used to prepare vacuole, mitochondria and cytosol fractions. Tryptophan synthase activity was exclusively found in the soluble fraction. Proteinases A, B and C as well as the tryptophan-synthase-inactivating activity were mainly found in the vacuole fraction. The heat-stable activities inhibiting proteinase and tryptophan-synthase-inactivating enzyme appeared in the soluble fraction. The subcellular separation of tryptophan synthase and the tryptophan-synthase-inactivating activities explains why in crude extracts from stationary yeast cells, high tryptophan synthase activities are observed in spite of high tryptophan-synthase-inactivating activity. The proteinases of a freshly prepared vacuole fraction from yeast spheroplasts are unable to inactivate externally added tryptophan synthase unless the organelles are disrupted by sonication or osmotic shock.
TL;DR: In this article, the formation of a high concentration of alcohol in sake mash is related to the lipid metabolism of the yeasts, especially linoleic acid, incorporated to the yeast cells grown anaerobically in the statical fermentation test.
Abstract: By use of the chemically defined synthetic medium, the formation of high concentration of alcohol, reaching 20–21 percent, was accomplished by Saccharomyces sake, at 20°C within 20 days, under a gradual addition of sucrose. Unsaturated fatty acid-containing phospholipid- macromolecule (albumin or methylcellulose) complex was the essential structure for the high concentration alcohol-producing factor. Unsaturated fatty acids, especially linoleic acid, incorporated to the yeast cells grown anaerobically in the statical fermentation test from the koji mold phosphatidylcholine-methylcellulose complex. These data show that the formation of a high concentration of alcohol in sake mash is related to the lipid metabolism of the yeasts.