Yeast

About: Yeast is a research topic. Over the lifetime, 31777 publications have been published within this topic receiving 868967 citations. The topic is also known as: yeasts.

A study of ethanol tolerance in yeast.

Abstract: The ethanol tolerance of yeast and other microorganisms has remained a controversial area despite the many years of study. The complex inhibition mechanism of ethanol and the lack of a universally accepted definition and method to measure ethanol tolerance have been prime reasons for the controversy. A number of factors such as plasma membrane composition, media composition, mode of substrate feeding, osmotic pressure, temperature, intracellular ethanol accumulation, and byproduct formation have been shown to influence the ethanol tolerance of yeast. Media composition was found to have a profound effect upon the ability of a yeast strain to ferment concentrated substrates (high osmotic pressure) and to ferment at higher temperatures. Supplementation with peptone-yeast extract, magnesium, or potassium salts has a significant and positive effect upon overall fermentation rates. An intracellular accumulation of ethanol was observed during the early stages of fermentation. As fermentation proceeds, the intracellular and extracellular ethanol concentrations become similar. In addition, increases in osmotic pressure are associated with increased intracellular accumulation of ethanol. However, it was observed that nutrient limitation, not increased intracellular accumulation of ethanol, is responsible to some extent for the decreases in growth and fermentation activity of yeast cells at higher osmotic pressure and temperature.

Absolute mRNA levels and transcriptional initiation rates in Saccharomyces cerevisiae

Abstract: We quantitate the absolute levels of individual mRNAs per yeast cell by hybridizing total yeast RNA with an excess of gene-specific 32P-oligonucleotides, and digesting the resulting RNA-DNA hybrids with S1 nuclease. By comparing the his3 hybridization signal from a known amount of yeast cells to the signal generated by a known amount of his3 RNA synthesized in vitro, we determine that yeast strain KY114 growing in yeast extract/peptone/glucose medium at 30 degrees C contains seven molecules of his3 mRNA per cell. Using a galactose shut-off procedure, we determined that the half-life of his3 mRNA is approximately 11 min under these conditions. From these observations, we calculate that one his3 mRNA molecule is synthesized every 140 s. Analysis of other his3 promoter derivatives suggests that the maximal transcriptional initiation rate in yeast cells is one mRNA molecule every 6-8 s. Using his3 as an internal standard, the number of mRNA molecules per cell have been determined for ded1, trp3, rps4, and gall under a variety of growth conditions. From these results, the absolute mRNA level of any yeast gene can be determined in a single hybridization experiment. Moreover, the rate of transcriptional initiation can be determined for mRNAs whose decay rates are known.

Molecular genetics of yeast :a practical approach

Abstract: 1: Procedures for isolating yeast DNA for different purposes. 2: Construction of cloning and expression vectors. 3: Cosmid cloning of yeast DNA. 4: The construction and use of cDNA libraries for genetic selections. 5: Pulsed field gel electrophoresis. 6: Plasmid shuffling and mutant isolation. 7: Ty insertional mutagenesis. 8: High efficiency transformation with lithium acetate. 9: Measurement of transcription. 10: Measurement of mRNA stability. 11: Production of foreign proteins at high level. 12: Cell-free translation of natural and synthetic mRNAs. 13: Virus-like particles: Ty retrotransposons. 14: The K1 killer toxin: molecular and genetic applications to secretion and cell surface assembly. 15: Immuno-electron microscopy. 16: Industrial Saccharomyces yeasts

Srb10/Cdk8 regulates yeast filamentous growth by phosphorylating the transcription factor Ste12

Abstract: The budding yeast Saccharomyces cerevisiae differentiates into filamentous invasively growing forms under conditions of nutrient limitation1,2. This response is dependent on the transcription factor Ste12 and on the mating pheromone-response mitogen-activated protein (MAP) kinase cascade1, but a mechanism for regulation of Ste12 by nutrient limitation has not been defined. Here we show that Ste12 function in filamentous growth is regulated by the cyclin-dependent kinase Srb10 (also known as Cdk8), which is associated with the RNA polymerase II holoenzyme. Srb10 inhibits filamentous growth in cells growing in rich medium by phosphorylating Ste12 and decreasing its stability. Under conditions of limiting nitrogen, loss of Srb10 protein and kinase activity occurs, with a corresponding loss of Ste12 phosphorylation. Mutation of the Srb10-dependent phosphorylation sites increases pseudohyphal development but has no effect on the pheromone response of haploid yeast. Srb10 kinase activity is also regulated independently of the mating pheromone-response pathway. This indicates that Srb10 controls Ste12 activity for filamentous growth in response to nitrogen limitation and is consistent with the hypothesis that Srb10 regulates gene-specific activators in response to physiological signals to coordinate gene expression with growth potential.