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.

Comparative functional genomics of the fission yeasts

Abstract: The fission yeast clade--comprising Schizosaccharomyces pombe, S. octosporus, S. cryophilus, and S. japonicus--occupies the basal branch of Ascomycete fungi and is an important model of eukaryote biology. A comparative annotation of these genomes identified a near extinction of transposons and the associated innovation of transposon-free centromeres. Expression analysis established that meiotic genes are subject to antisense transcription during vegetative growth, which suggests a mechanism for their tight regulation. In addition, trans-acting regulators control new genes within the context of expanded functional modules for meiosis and stress response. Differences in gene content and regulation also explain why, unlike the budding yeast of Saccharomycotina, fission yeasts cannot use ethanol as a primary carbon source. These analyses elucidate the genome structure and gene regulation of fission yeast and provide tools for investigation across the Schizosaccharomyces clade.

Methods in yeast genetics : a Cold Spring Harbor Laboratory course manual

Abstract: Genetic nomenclature. Looking at yeast cells. Experiments: isolation and characterization of auxotrophic, temperature-sensitive, and UV-sensitive mutants meiotic mapping mitotic recombination and random spore analysis transformation of yeast cytoduction and karyogamy gene replacement isolation of ras2 suppressors manipulating cell types isolation of suppressors of telomeric silencing by insertional shuttle mutagenesis lacZ gene fusion expression in yeast immunofluorescent staining of yeast cells. Techniques and protocols: super-efficient transformation of yeast with lithium acetate/SS-DNA/PEG other yeast transformation methods yeast colony hybridization yeast DNA isolations yeast protein extracts yeast RNA isolation northern analysis - formaldehyde agarose gel, blotting, and hybridization to filters alkaline southern blotting procedure scoring killer factor hydroxylamine mutagenesis of plasmid DNA assay of galactosidase in yeast transformation of bacteria (CaC12 method) plate assay for carboxypeptidase western blotting protein extracts random spore analysis yeast vital strains yeast immunofluorescence with antibodies actin staining in fixed cells PCR analysis of genotype quick e coli plasmid DNA mini-prep. Appendices: media stock preservation yeast genetic map grids electrophoretic karotypes of strains for southern blot mapping strains counting yeast cells with a standard hemocytometer chamber.

Engineered Saccharomyces cerevisiae capable of simultaneous cellobiose and xylose fermentation.

Abstract: The use of plant biomass for biofuel production will require efficient utilization of the sugars in lignocellulose, primarily glucose and xylose. However, strains of Saccharomyces cerevisiae presently used in bioethanol production ferment glucose but not xylose. Yeasts engineered to ferment xylose do so slowly, and cannot utilize xylose until glucose is completely consumed. To overcome these bottlenecks, we engineered yeasts to coferment mixtures of xylose and cellobiose. In these yeast strains, hydrolysis of cellobiose takes place inside yeast cells through the action of an intracellular β-glucosidase following import by a high-affinity cellodextrin transporter. Intracellular hydrolysis of cellobiose minimizes glucose repression of xylose fermentation allowing coconsumption of cellobiose and xylose. The resulting yeast strains, cofermented cellobiose and xylose simultaneously and exhibited improved ethanol yield when compared to fermentation with either cellobiose or xylose as sole carbon sources. We also observed improved yields and productivities from cofermentation experiments performed with simulated cellulosic hydrolyzates, suggesting this is a promising cofermentation strategy for cellulosic biofuel production. The successful integration of cellobiose and xylose fermentation pathways in yeast is a critical step towards enabling economic biofuel production.

Isolation and characterization of a sucrose carrier cDNA from spinach by functional expression in yeast.

Abstract: Active loading of the phloem with sucrose in leaves is an essential part of the process of supplying non-photosynthetic tissues with carbon and energy. The transport is protein mediated and coupled to proton-symport, but so far no sucrose carrier gene has been identified. Using an engineered Saccharomyces cerevisiae strain, a cDNA from spinach encoding a sucrose carrier was identified by functional expression. Yeast strains that allow the phenotypic recognition of a sucrose carrier activity were constructed by expressing a cytoplasmic invertase from yeast, or the potato sucrose synthase gene, in a strain unable to transport or grow on sucrose due to a deletion in the SUC2 gene. A spinach cDNA expression library established from the poly(A)+ RNA from source leaves of spinach and cloned in a yeast expression vector yielded transformed yeast clones which were able to grow on media containing sucrose as the sole carbon source. This ability was strictly linked to the presence of the spinach cDNA clone pS21. Analysis of the sucrose uptake process in yeast strains transformed with this plasmid show a pH-dependent uptake of sucrose with a Km of 1.5 mM, which can be inhibited by maltose, alpha-phenylglucoside, carbonyl cyanide m-chlorophenylhydrazone and p-chloromercuribenzenesulfonic acid. These data are in accordance with measurements using both leaf discs and plasma membrane vesicles from leaves of higher plants. DNA sequence analysis of the pS21 clone reveals the presence of an open reading frame encoding a protein with a molecular mass of 55 kDa. The predicted protein contains several hydrophobic regions which could be assigned to 12 membrane-spanning regions.(ABSTRACT TRUNCATED AT 250 WORDS)