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  • Articles  (6,204)
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  • 1
    ISSN: 1572-8773
    Keywords: catalase ; copper resistance ; pH-dependent growth ; Saccharomyces cerevisiae ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A strain of Saccharomyces cerevisiae has been adapted to increasing concentrations of copper at two different pH values. The growth curve at pH 5.5 is characterized by a time generation increasing with the amount of added copper. A significant decrease of cell volume as compared with the control is also observed. At pH 3 the cells grow faster than at pH 5.5 and resist higher copper concentrations (3.8 against 1.2 mm). Experimental evidence indicates that, after copper treatment, the metal is not bound to the cell wall, but is localized intracellularly. A significant precipitation of copper salts in the medium was observed only at pH 5.5. Increased levels of superoxide dismutase (SOD) activity were observed in copper-treated cells and which persisted after 20 subsequent inocula in a medium without added metal. On the contrary, catalase activity was not stimulated by copper treatment and, hence, not correlated with SOD levels. The mechanism of copper resistance, therefore, probably involves a persistent induction of SOD, but not of catalase, and it is strongly pH-dependent.
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  • 2
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    Cellular and molecular life sciences 50 (1994), S. 429-437 
    ISSN: 1420-9071
    Keywords: Genetics ; ecology ; DNA-transfer ; conjugation ; transformation ; transduction ; transposons ; dormant cells ; epilithon ; microbial colonisation ; symbiosis ; virus resistance ; biosafety ; release of genes ; insults to humanity ; evolution ; biodiversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.
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  • 3
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    Journal of molecular evolution 38 (1994), S. 363-368 
    ISSN: 1432-1432
    Keywords: Saccharomyces cerevisiae ; 2-μm circle ; DNA sequencing ; Horizontal transmission ; Site-specific recombination ; Selfish DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the nucleotide substitution pattern over the entire genome of two unique variants of the 6,300-bp selfish DNA (2 μm) plasmid in Saccharomyces cerevisiae. The DNA sequence of the left-unique region is identical among 2-μm variants, while the right-unique region shows substantial divergence. This chimeric pattern cannot be explained by neutral or Darwinian selection models. We propose that horizontal transmission of the 2-μm plasmid coupled with a directed, polarized gene conversion maintains the DNA sequence of the left-unique region, whereas the right-unique region is subject to random drift and Darwinian selection.
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  • 4
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    Journal of biomedical science 1 (1994), S. 201-203 
    ISSN: 1423-0127
    Keywords: Hypertension ; Eicosanoid ; Rat ; Genetics ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H2 and/or thromboxane A2 in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.
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  • 5
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    Sexual plant reproduction 7 (1994), S. 290-296 
    ISSN: 1432-2145
    Keywords: Secale cereale ; Polyembryony ; Chromosome mosaics ; Rye ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have obtained one plant regenerated from rye tissue culture which showed a high percentage of polyembryonic seeds in its progeny. The mutation inducing the development of extra embryos is also influencing erroneous cell division, mitosis and meiosis. The genetic analysis indicated that the aptitude for polyembryonic seed formation is a heritable trait controlled by a dominant gene. However, for expression of the phenotype the female parent should have a specific cytoplasm.
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  • 6
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    Current genetics 26 (1994), S. 95-99 
    ISSN: 1432-0983
    Keywords: Translational fidelity ; Paromomycin ; Stuttering ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Missense errors in the translation of mRNAs in Saccharomyces cerevisiae were screened by looking for charge heterogeneity of proteins on two-dimensional gels resulting from the substitution of charged and neutral amino acids. No such mistranslation was detected in wild-type yeast strains grown in the presence of the translational error-inducing antibiotic paromomycin. However, paromomycin-induced mistranslation of a heterologous mRNA, encoding human phosphoglycerate kinase expressed in yeast, was seen. We suggest that the combination of error-prone translation of a heterologous mRNA, and growth in the presence of paromomycin, leads to an accumulation of mistranslated proteins that can be detected by two-dimensional gel electrophoresis.
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  • 7
    ISSN: 1432-0983
    Keywords: ABC superfamily ; Multidrug resistance ; Saccharomyces cerevisiae ; YDR1 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A multidrug resistance gene, YDR1, of Saccharomyces cerevisiae, which encodes a 170-kDa protein of a member of the ABC superfamily, was identified. Disruption of YDR1 resulted in hypersensitivity to cycloheximide, cerulenin, compactin, staurosporine and fluphenazine, indicating that YDR1 is an important determinant of cross resistance to apparently-unrelated drugs. The Ydr1 protein bears the highest similarity to the S. cerevisiae Snq2 protein required for resistance to the mutagen 4-NQO. The drug-specificity analysis of YDR1 and SNQ2 by gene disruption, and its phenotypic suppression by the overexpressed genes, revealed overlapping, yet distinct, specificities. YDR1 was responsible for cycloheximide, cerulenin and compactin resistance, whereas, SNQ2 was responsible for 4-NQO resistance. The two genes had overlapping specificities toward staurosporine and fluphenazine. The transcription of YDR1 and SNQ2 was induced by various drugs, both relevant and irrelevant to the resistance caused by the gene, suggesting that drug specificity can be mainly attributed to the functional difference of the putative transporters. The transcription of these genes was also increased by heat shock. The yeast drug-resistance system provides a novel model for mammalian multidrug resistance.
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  • 8
    ISSN: 1432-0983
    Keywords: Psoralen ; DNA repair mutants ; Gene conversion ; Recombination ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the DNA repair genePSO3 on photoactivated psoralen-induced meiotic recombination, gene conversion, reverse mutation, and on survival, was assayed in diploid strains ofSaccharomyces cerevisiae homozygous for the wild-type or thepso3-1 mutant allele. Sporulation was normal in thepso3-1 diploid. Wild-type and mutant strains had the same sensitivity to photoactivated monofunctional psoralen (3-CPs+UVA) in meiosis-uncommitted and meiosis-committed stages. The mutant showed higher sensitivity to photoactivated bifunctional psoralen (8-MOP+UVA) during all stages of the meiotic cycle. Mutation induction by 3-CPs+UVA or 8-MOP+UVA in meiosis-committed cells revealed no significant differences between wild-type and thepso3-1 mutant. The status of thePSO3 gene has no influence on the kinetics of induction of gene conversion and crossing-over after 3-CPs+UVA treatment in meiosis-committed cells: gene conversion was blocked while recombination was induced. After treatment with 8-MOP+UVA gene conversion was also blocked in both strains while crossing-over could only be observed in meiosis-committed wild-type cells.
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  • 9
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    Current genetics 25 (1994), S. 180-183 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; In-vivo cloning ; Non-replicative vectors ; Homologous recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have devised a new strategy to clone DNA sequences from an yeast autonomously-propagating plasmid into a non-autonomous integrative vector by in-vivo recombination. The method consists of a first step in which the replicative plasmid carrying the DNA fragment of interest forms a co-integrate with the non-replicative plasmid by an induced in-vivo reciprocal exchange accompanied by gene conversion. The dimeric plasmid obtained is then purified and cut with an appropriate restriction enzyme and ligated independently to obtain the two intact monomeric plasmids, the original autonomous plasmid plus the new non-autonomous plasmid carrying the subcloned DNA fragment. The dimeric co-integrate can also serve as substrate for a second in-vivo reciprocal exchange that produces new autonomous plasmids carrying the desired DNA fragment. The technique considerably expands the applications of in-vivo cloning in yeast by complementing three important characteristics of previously published methods: (1) it can be used to clone into non-propagating vectors; (2) co-transformation experiments are not required; and (3) the intermediate co-integrate can be used to generate new types of autonomously-propagating plasmids directly. These characteristics are independent of whether the DNA insert is flanked by appropriate restriction sites or whether it does, or does not, express a detectable phenotype in yeast. The method is particularly useful for the cloning of large DNA fragments and can be used for plasmids from organisms other than yeasts.
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  • 10
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    Current genetics 25 (1994), S. 291-298 
    ISSN: 1432-0983
    Keywords: Cytochrome c 1 ; Cytochrome c 1 heme lyase ; GRF2p ; Glucose repression ; HAPp ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we examine the expression of the Saccharomyces cerevisiae CYT2 gene, which encodes cytochrome c 1 heme lyase. This enzyme is required for covalent attachment of heme to apocytochrome c 1, a subunit of the mitochondrial respiratory chain. Transcription of the 1-kb CYT2 mRNA initiates at four prominent sites at a distance of 52–225 bp in front of the AUG start codon. The level of CYT2 mRNA is not influenced by the presence or absence of oxygen or of heme, but it is subject to carbonsource control. The concentration of the CYT2 mRNA is significantly reduced in glucose-grown cells as compared to cells grown under non-repressing conditions. Neither the HAPp activator proteins nor MIG1p, a repressor protein involved in glucose repression, seem to mediate this effect.
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  • 11
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; recA gene expression ; UV radiation ; Mitotic gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the Escherichia coli RecA protein on mitotic recombination in the diploid D7 strain of Saccharomyces cerevisiae damaged by UV radiation was investigated. The D7 strain was transformed by two modified versions of the pNF2 plasmid: one, containing the ADH-1 promoter, and the other containing the recA gene tandemly arranged behind the ADH-1 promoter region. Immunological analysis proved the presence of the 38-kDa RecA protein in D7/pNF2ADHrecA transformants. We observed a positive effect of recA gene expression on mitotic gene conversion, mainly at higher doses of UV radiation. The results indicate that a RecA-like activity could participate in steps preceeding mitotic conversion events in yeast.
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  • 12
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    Current genetics 26 (1994), S. 15-20 
    ISSN: 1432-0983
    Keywords: Cell-division cycle ; Mitochondrial genome ; Nuclear mutation ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In former studies it was found that the ERV1 gene is essential for cell viability and for the biogenesis of functional mitochondria. A temperature-sensitive nuclear mutant exhibits a severe reduction in all the mitochondrial transcripts. Elimination of the gene leads to growth arrest after a few cell divisions. The putative gene product bears the characteristics of a regulatory factor since it has low expression rate and a high content of charged amino acids. In this study it is further verified that the ERV1 gene alone is responsible for the observed cellular and mitochondrial defects. The 5′ region of the gene is analysed by DNA deletions and complementation studies. Expression of the gene under the control of the GAL1-10 promoter in a disruption strain of ERV1 allows a more detailed specification of its influence on mitochondrial and cellular functions. Immediate and complete loss of mitochondrial genomes is observed after the promoter has been shut off, whereas the yeast cells are still able to grow for a limited time under these conditions. Analysis of the cells by in-vivo DNA flurorescence demonstrates a specific arrest in the cell-division cycle as the terminal phenotype. To further characterize the temperature-sensitive allele of ERV1 the mutated gene has been isolated and sequenced. A single point mutation which leads to the exchange of a single amino acid is found in the reading frame.
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  • 13
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Nuclear gene ; Mitochondria ; Mitochondrial ribosomal protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nuclear gene MRP-L13 of Saccharomyces cerevisiae, which codes for the mitochondrial ribosomal protein YmL13, has been cloned and characterized. It is a single-copy gene residing on chromosome XI. Its nucleotide sequence was found to be identical to that of the previously reported ORF YK105. A comparison of the predicted protein sequence of the MRP-L13 gene product and the actual N-terminal amino-acid sequence of the isolated YmL13 protein indicated that the mature protein is preceded by a mitochondrial signal peptide of 86 amino-acid residues, which is the longest among all known mitochondrial ribosomal proteins of S. cerevisiae. No sequence similarity was found to any other ribosomal protein in the current databases. The transcription of MRP-L13 was found to be repressed in the presence of glucose. Its protein product is not strictly essential for mitochondrial functions, but disruption of the gene by insertion of LEU2 noticeably affected cellular growth on non-fermentable carbon sources.
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  • 14
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    Current genetics 25 (1994), S. 289-289 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Inducible antisense gene ; Acetolactate synthase ; Bradytrophic phenocopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A previous report of the use of antisense RNA to regulate gene expression in yeast is incorrect.
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  • 15
    ISSN: 1432-0983
    Keywords: Psoralen sensitivity ; Saccharomyces cerevisiae ; DNA repair ; Oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The complementation and genetical analysis of yeast mutants sensitive to photoactivated 3-carbethoxy-psoralen define three novel recessive mutant alleles pso-5-1, pso6-1, and pso7-1. Their cross-sensitivity to UV254nm, radiomimetic mutagens, and to chemicals enhancing oxidative stress suggest that these mutants are either impaired in metabolic steps protecting from oxidative stress or in mechanisms of the repair of oxygen-dependent DNA lesions. None of the three novel mutant alleles block the induction of reverse mutation by photoactivated mono- and bi-functional psoralens, nitrogen mustards, or UV254nm.
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  • 16
    ISSN: 1432-0983
    Keywords: tRNA processing ; Saccharomyces cerevisiae ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used a genetic approach to study the nuclear factors involved in the biogenesis of mitochondrial tRNAs. A point mutation in the mitochondrial tRNAAsp gene of Saccharomyces cerevisiae had previously been shown to result in a temperature-sensitive respiratory-deficient phenotype as a result of the absence of 3′ end-processing of the tRNAAsp. Analysis of mitochondrial revertants has shown that all revertants sequenced have a G-A compensatory change at position 53, which restores the hydrogen-bond with the mutated nucleotide. We then searched for nuclear suppressors to identify the nuclear gene(s) involved in mitochondrial tRNA 3′ end-processing. One such suppressor mutation was further characterized: it restores tRNAAsp maturation and growth at 36°C on glycerol medium in heterozygous diploids, but leads to a defective growth phenotype in haploids.
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  • 17
    ISSN: 1432-0983
    Keywords: Overexpression ; Peroxisomes ; Saccharomyces cerevisiae ; Stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have constructed a gene coding for the 12-kDa intermediate form of the 2s methionine-rich protein from Bertholletia excelsa seeds. This protein, expressed intracellularly in yeast, is characterised by a 20-min balf-life. By adding 11 amino acids corresponding to the peroxisome-targeting sequence (PTSc) of luciferase, we have significantly increased its half-life. This stabilization allowed accumulation of the BZN protein into the peroxisome as judged by cell fractionation. Accumulation of the 12-kDa protein results in a significant increase of the total methionine content in yeast cells (30%) indicating that such a microorganism could represent a practicable protected shuttl for an animal-feed additive.
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  • 18
    ISSN: 1432-0983
    Keywords: Cytochrome oxidase ; Revertant ; Mitochondria ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three respiratory-deficient mutants of cytochrome oxidase subunit I in the yeast mitochondrion have been sequenced. They are located in, or near, transmembrane segment VI, the catalytic core of the enzyme. Respiratory-competent revertants have been selected and studied. The mutant V244M was found to revert at the same site in valine (wild-type), isoleucine or threonine. The revertants of the mutant G251R were of three types: glycine (wild-type), serine and threonine at position 251. A search for second-site mutations was carried out but none were found. Among 60 revertants tested, the mutant K265M was found to revert only to the wild-type allele.
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  • 19
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    Archives of microbiology 162 (1994), S. 211-214 
    ISSN: 1432-072X
    Keywords: Killer toxin ; Saccharomyces cerevisiae ; Toxin binding ; Cell wall receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A recently described new method for determination of killer toxin activity was used for kinetic measurenments of K1 toxin binding. The cells of the killer sensitive strain Saccharomyces cerevisiae S6 were shown to carry two classes of toxin binding sites differing widely in their half-saturation constants and maximum binding rates. The low-affinity and high-velocity binding component (K T1=2.6x109 L.U./ml, V max1=0.19 s-1) probably reflects diffusion-limited binding to cell wall receptors; the high-affinity and low-velocity component (K T2=3.2x107 L.U./ml, V max2=0.03 s-1) presumably indicates the binding of the toxin to plasma membrane receptors. Adsorption of most of the killer toxin K1 to the surface of sensitive cells occured within 1 min and was virtually complete within 5 min. The amount of toxin that saturated practically all cell receptors was about 600 lethal units (L.U.) per cell of S. cerevisiae S6.
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  • 20
    ISSN: 1432-072X
    Keywords: Rylux BSU ; Fluorescent brightener ; Cell walls ; Chitin synthase ; Glucan synthase ; Yeast ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rylux BSU, a new fluorescent brightener from the family of 4,4′-diaminostilbene-2,2′disulfonic acid derivatives, inhibited growth and cytokinesis of the yeast Saccharomyces cerevisiae. In the presence of 0.1–1 mg/ml Rylux BSU the cells grew in clumps, had irregular shape and were larger than controls. They formed apparently normal primary septa but their secondary septa and lateral cell walls, especially those in older cells, were abnormally thick with large deposits of amorphous wall material in the periplasmic spaces all over the cell surface. Chitin content in the cell walls of cells grown in the presence of Rylux BSU was increased 2 to 5 times in comparison to that of the controls and glucan content was reduced by up to 30%. In the in vitro assays with particulate membrane fractions, Rylux BSU acted as a non-competitive inhibitor of β-1,3-glucan synthase with inhibitory constant K i=1.75 mg/ml whereas the chitin synthase was inhibited to a much lesser extent. From the difference of the effects of Rylux BSU on the synthesis of chitin in vivo and in vitro it is concluded that the brightener interacts with chitin synthase only indirectly, possibly by influencing the properties of integral plasma membrane.
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  • 21
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    Archives of microbiology 162 (1994), S. 211-214 
    ISSN: 1432-072X
    Keywords: Key words     Killer toxin ; Saccharomyces cerevisiae ; Toxin binding ; Cell wall receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      A recently described new method for determination of killer toxin activity was used for kinetic measurements of K1 toxin binding. The cells of the killer sensitive strain Saccharomyces cerevisiae S6 were shown to carry two classes of toxin binding sites differing widely in their half-saturation constants and maximum binding rates. The low-affinity and high-velocity binding component (K T1 = 2.6 × 109 L.U./ml, V max1 = 0.19 s– 1) probably reflects diffusion-limited binding to cell wall receptors; the high-affinity and low-velocity component (K T2 = 3.2 × 107 L.U./ml, V max2 = 0.03 s– 1) presumably indicates the binding of the toxin to plasma membrane receptors. Adsorption of most of the killer toxin K1 to the surface of sensitive cells occured within 1 min and was virtually complete within 5 min. The amount of toxin that saturated practically all cell receptors was about 600 lethal units (L.U.) per cell of S. cerevisiae S6.
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  • 22
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    Journal of industrial microbiology and biotechnology 13 (1994), S. 30-34 
    ISSN: 1476-5535
    Keywords: Phytate ; Saccharomyces cerevisiae ; Polyacrylamide gel ; Inositol phosphates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Saccharomyces cerevisiae in the form of baker's yeast, cells cultivated on a yeast extract-peptone-glucose medium, as well as cells immobilized in 18% (w/v) polyacrylamide gel showed the ability to hydrolyze 1.727 mM sodium phytate solution at 45°C, pH 4.6, in a stirred tank reactor. Seventy percent yield of dephosphorylation was observed after 2 h using a baker's yeast concentration of 5.8 g dry matter per 100 ml. Hydrolytic activity at 1.8–2.0 μM Pi min−1 was observed between 1st and 3rd h of the reaction in cells cultured 24 or 48 h. No inhibition by the substrate was found at sodium phytate concentrations of 0.587–1.727 mM. After 1.5 h of hydrolysis a single, well distinguished peak ofmyo-inositol-triphosphate was the main product found. By means of immobilization the stability of the biocatalyst was enhanced 3.3-fold and reached its half-life at 64 ninety-minute runs.
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  • 23
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    Journal of industrial microbiology and biotechnology 13 (1994), S. 269-272 
    ISSN: 1476-5535
    Keywords: Wine ; Yeasts ; Fatty acids ; Ethyl esters ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The evolution of the cell and must contents of three short-chain fatty acids (C6, C8 and C10) and their ethyl esters during fermentations withSaccharomyces cerevisiae racescerevisiae, bayanus andcapensis were studied. The former is a fermentative yeast and the last two are ‘flor’ film yeasts. The acid concentrations in the musts increased throughout the alcoholic fermentations, and maximum cell concentrations of the fatty acids were reached after 48 h of fermentation. Maximum ester concentrations in the cells were attained after 48–72 h of fermentation. In the musts, ethyl octanoate and ethyl decanoate reached a peak also at this point, and ethyl hexanoate after 10 days. After 134 days,S. cerevisiae racecapensis formed a thick ‘flor’ film whileS. cerevisiae racebayanus developed a thin film andS. cerevisiae racecerevisiae formed no film. At this point, acid contents remained constant in the wines produced byS. cerevisiae racescerevisiae andbayanus, and decreased in those obtained with racecapensis. The ethyl ester contents tended to decrease with the exception of ethyl decanoate in the fermentations carried out byS. cerevisiae racescerevisiae andbayanus.
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  • 24
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    Molecular biology reports 20 (1994), S. 135-141 
    ISSN: 1573-4978
    Keywords: mitochondria ; multienzyme complex ; replication ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 40 S multienzyme complex containing mtDNA polymerase was isolated from mitochondria ofS. cerevisiae by density gradient centrifugation and by gel filtration chromatography. Besides DNA polymerase, RNA polymerase, primase, 3′→5′ exonuclease and an ATPase activities were found to be associated with it. The presence of some of these enzymes were confirmed by Western blot. This high molecular weight multienzyme complex containing DNA has most of the attributes of a putative replisome.
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  • 25
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; cDNA ; complementation ; erg20-2 yeast mutant ; farnesyl diphosphate synthase ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding farnesyl diphosphate synthase, an enzyme that synthesizes C15 isoprenoid diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate, was cloned from an Arabidopsis thaliana cDNA library by complementation of a mutant of Saccharomyces cerevisiae deficient in this enzyme. The A. thaliana cDNA was also able to complement the lethal phenotype of the erg20 deletion yeast mutant. As deduced from the full-length 1.22 kb cDNA nucleotide sequence, the polypeptide contains 343 amino acids and has a relative molecular mass of 39689. The predicted amino acid sequence presents about 50% identity with the yeast, rat and human FPP synthases. Southern blot analyses indicate that A. thaliana probably contains a single gene for farnesyl diphosphate synthase.
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  • 26
    ISSN: 1432-2242
    Keywords: Maize ; Restriction fragment length polymorphisms (RFLPs) ; Qualitative and quantitative inheritance ; Plant breeding ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Restriction fragment length polymorphisms (RFLPs) and one morphological marker were used to investigate quantitative trait loci (QTL) for morphological and physiological traits evaluated on 150 F2∶3 maize (Zea mays L.) lines derived from the cross of elite U.S. Corn Belt inbreds Mo17 and H99. F2∶3 lines were grown in a replicated experiment and evaluated for plant and ear heights and flowering traits. QTL were identified for each trait, and genetic effects were determined. Estimated gene action for the flowering traits was predominantly overdominance. Both parents contributed toward increased values for anthesis and silk emergence. QTL for increased plant and ear heights were usually contributed by the taller parent, Mo17. Estimated gene action for these traits was mainly partial to overdominance. QTL for plant height were located in the vicinity of loci defined by alleles with qualitative effects on plant height.
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  • 27
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    Theoretical and applied genetics 89 (1994), S. 959-963 
    ISSN: 1432-2242
    Keywords: Sugarcane ; Polyploidy ; Genetics ; Evolution ; Breeding ; DNA markers ; Arbitrarily primed PCR ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum ‘SES 208’ and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum ‘LA Purple’ and Saccharum robustum ‘ Mol 5829’. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.
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  • 28
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    Theoretical and applied genetics 89 (1994), S. 313-317 
    ISSN: 1432-2242
    Keywords: Genetics ; Rice ; Phosphorousefficiency ; Diallel analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inheritance of phosphorous (P) — deficiency tolerance in rice was investigated by a sevenparent diallel. The parent materials involved were four P-efficient (IR20, IR54, IR28, and Mahsuri), one moderately P-efficient (TN1), and two P-inefficient (IR31406333-1 and IR34686-179-1-2-1), genotypes. Relative tilering ability (RTA) under P-deficient and P-supplemented soil conditions was the parameter used in determining the tolerance level of the different genotypes. Diallel graph analysis revealed that tolerant parents have an excess of recessive genes, while moderate and susceptible parents possess more dominant genes. Genetic-component analysis suggested that both additive and dominance gene effects are involved in the inheritance of P-deficiency tolerance in rice. The trait exhibited over doiminance as confirmed by the graphical analysis. Narrow-sense heritability of the trait was moderate (0.50) and environmental effects were low. Both the general combining ability (GCA) and the specific combining ability (SCA) were significant, but GCA was more prevalent than SCA. Tolerant parents exhibited a high GCA whereas susceptibles have a very poor GCA, suggesting that tolerant parents were mostly enriched in additive genes and susceptible parents in non-additive genes. Crosses involving two high general combiners showed low SCA effects whereas crosses between poor general combiners manifested highly-significant SCA values.
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  • 29
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    Theoretical and applied genetics 88 (1994), S. 754-758 
    ISSN: 1432-2242
    Keywords: Potato breeding ; Potato leaf roll virus ; Virus resistance ; Major gene resistance ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concentration of potato leaf roll virus (PLRV), as measured by a quantitative enzyme-linked immunosorbent assay, in the foliage of potato plants (Solanum tuberosum) of cv ‘Maris Piper’ with secondary infection was 2900 ng/g leaf, whereas in clones G7445(1) and G7032(5) it was 180 ng/g leaf and 120 ng/g leaf, respectively. To examine the genetic control of resistance to PLRV multiplication, reciprocal crosses were made between the susceptible cultivar ‘Maris Piper’ and the two resistant clones, and the three parents were selfed. Seedling progenies of these families were grown to generate tubers of individual genotypes (clones). Clonally propagated plants were graft-inoculated, and their daughter tubers were collected and used to grow plants with secondary infection in which PLRV concentration was estimated. The expression of resistance to PLRV multiplication had a bimodal distribution in progenies from crosses between ‘Maris Piper’ and either resistant clone, and also in progeny from selfing the resistant parents, with genotypes segregating into high and low virus titre groups. Only the progeny obtained from selfing ‘Maris Piper’ did not segregate, all genotypes being susceptible to PLRV multiplication. The pattern of segregation obtained from these progenies fits more closely with the genetical hypothesis that resistance to PLRV multiplication is controlled by two unlinked dominant complementary genes, both of which are required for resistance, than with the simpler hypothesis that resistance is conferred by a single dominant gene, as published previously.
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  • 30
    ISSN: 1432-2242
    Keywords: Breeding ; Helminthosporium turcicum ; RFLP ; QTLs ; Disease-resistance ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RFLPs were used to investigate components of host-plant response to Exserohilum turcicum in 150 unselected F2∶3 lines of a B52/Mo17 maize population. Following inoculation with spore suspensions of the pathogen (race 0), components of disease development were measured and then quantitative trait mapping was performed to identify the location and effects of quantitative trait loci (QTLs) determining host-plant response. Components of interest were the average number of lesions per leaf, the average percent leaf tissue diseased (severity) and the average size of lesions (cm2). Based on a LOD threshold of 2.31 (P〈0.05), the number of lesions appears to be associated with QTLs on chromosomes 1S, 3L, 5S. Severity was associated with analogous regions and, in addition, QTLs on chromosomes 7L and 8L. Most QTLs, for either of these two components, involve additive gene action and partial dominance or overdominance. In contrast, lesion size was associated with QTLs on chromosomes 7L and 5L; recessive gene action may be involved at 7L.
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  • 31
    ISSN: 1432-2242
    Keywords: Genetics ; Disease resistance ; Monocots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An F2 oat population was produced by crossing the diploid (n=7) species Avena strigosa (CI 3815) with A. wiestii (CI 1994), resistant and susceptible, respectively, to 40 isolates of Puccinia coronata, the causal agent of crown rust. Eighty-eight F2 individuals were used to construct an RFLP linkage map representing the A genome of cultivated hexaploid oat. Two hundred and eight RFLP loci have been placed into 10 linkage groups. This map covers 2416 cM, with an average of 12 cM between RFLP loci. Eighty-eight F3 lines, derived from F2 individuals used to construct the map, were screened for resistance to 9 isolates of P. coronata. One locus, Pca, was found to confer a dominant resistance phenotype to isolates 203, 258, 263, 264B, 290, 298, 325A, and 345. Pca also conferred resistance to isolate 276; however, an unlinked second gene may also be involved.
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  • 32
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    Behavioral ecology and sociobiology 34 (1994), S. 117-409 
    ISSN: 1432-0762
    Keywords: Social insects ; Apis mellifera ; Division of labor ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variability exists among worker honey bees for components of division of labor. These components are of two types, those that affect foraging behavior and those that affect life-history characteristics of workers. Variable foraging behavior components are: the probability that foraging workers collect (1) pollen only; (2) nectar only; and (3) pollen and nectar on the same trip. Life history components are: (1) the age the workers initiate foraging behavior; (2) the length of the foraging life of a worker; and (3) worker length of life. We show how these components may interact to change the social organization of honey bee colonies and the lifetime foraging productivity of individual workers. Selection acting on foraging behavior components may result in changes in the proportion of workers collecting pollen and nectar. Selection acting on life-history components may affect the size of the foraging population and the distribution of workers between within nest and foraging activities. We suggest that these components define possible sociogenic “pathways” through which colony-level natural selection can change social organization. These pathways may be analogous to developmental pathways in the morphogenesis of individual organisms because small changes in behavioral or life history components of individual workers may lead to major changes in the organizational structure of colonies.
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  • 33
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    Behavioral ecology and sociobiology 35 (1994), S. 99-107 
    ISSN: 1432-0762
    Keywords: Key words Apis mellifera ; Genetics ; Drone production ; Allozymes ; Reproductive conflict
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously we reported that there are subfamily differences in drone production in queenless honey bee colonies, but these biases are not always explained by subfamily differences in oviposition behavior. Here we determine whether these puzzling results are best explained by either inadequate sampling of the laying worker population or reproductive conflict among workers resulting in differential treatment of eggs and larvae. Using colonies composed of workers from electrophoretically distinct subfamilies, we collected samples of adult bees engaged in the following behavior: “true” egg laying, “false” egg laying, indeterminate egg laying, egg cannibalism, or nursing (contact with larvae). We also collected samples of drone brood at four different ages: 0 to 2.5-h-old eggs, 0 to 24-h-old eggs, 3 to 8-day-old larvae, and 9 to 14-day-old larvae and pupae. Allozyme analyses revealed significant subfamily differences in the likelihood of exhibiting egg laying, egg cannibalism, and nursing behavior, as well as significant subfamily differences in drone production. There were no subfamily differences among the different types of laying workers collected from each colony, suggesting that discrepancies between subfamily biases in egg-laying behavior and drone production are not due to inadequate sampling of the laying worker population. Subfamily biases in drone brood production within a colony changed significantly with brood age. Laying workers had significantly more developed ovaries than either egg cannibals or nurses, establishing a physiological correlate for the observed behavioral genetic differences. These results suggest there is reproductive conflict among subfamilies and individuals within queenless colonies of honey bees. The implications of these results for the evolution of reproductive conflict, in both queenright and queenless contexts, are discussed.
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  • 34
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    Behavioral ecology and sociobiology 34 (1994), S. 125-137 
    ISSN: 1432-0762
    Keywords: Social insects ; Apis mellifera ; Division of labor ; Genetics ; Nepotism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three experiments were performed to determine whether brood care in honey bee colonies is influenced by colony genetic structure and by social context. In experiment 1, there were significant genotypic biases in the relative likelihood of rearing queens or workers, based on observations of individually labeled workers of known age belonging to two visually distinguishable subfamilies. In experiment 2, no genotypic biases in the relative likelihood of rearing drones or workers was detected, in the same colonies that were used in experiment 1. In experiment 3, there again were significant genotypic differences in the likelihood of rearing queens or workers, based on electrophoretic analyses of workers from a set of colonies with allozyme subfamily markers. There also was an overall significant trend for colonies to show greater subfamily differences in queen rearing when the queens were sisters (half- and super-sisters) rather than unrelated, but these differences were not consistent from trial to trial for some colonies. Results of experiments 1 and 3 demonstrate genotypic differences in queen rearing, which has been reported previously based on more limited behavioral observations. Results from all three experiments suggest that genotypic differences in brood care are influenced by social context and may be more pronounced when workers have a theoretical opportunity to practice nepotism. Finally, we failed to detect persistent interindividual differences in bees from either subfamily in the tendency to rear queen brood, using two different statistical tests. This indicates that the probability of queen rearing was influenced by genotypic differences but not by the effect of prior queen-rearing experience. These results suggest that subfamilies within a colony can specialize on a particular task, such as queen rearing, without individual workers performing that task for extended periods of time.
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  • 35
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    Behavioral ecology and sociobiology 35 (1994), S. 99-107 
    ISSN: 1432-0762
    Keywords: Apis mellifera ; Genetics ; Drone production ; Allozymes ; Reproductive conflict
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously we reported that there are subfamily differences in drone production in queenless honey bee colonies, but these biases are not always explained by subfamily differences in oviposition behavior. Here we determine whether these puzzling results are best explained by either inadequate sampling of the laying worker population or reproductive conflict among workers resulting in differential treatment of eggs and larvae. Using colonies composed of workers from electrophoretically distinct subfamilies, we collected samples of adult bees engaged in the following behavior: “true” egg laying, “false” egg laying, indeterminate egg laying, egg cannibalism, or nursing (contact with larvae). We also collected samples of drone brood at four different ages: 0 to 2.5-h-old eggs, 0 to 24-h-old eggs, 3 to 8-day-old larvae, and 9 to 14-day-old larvae and pupae. Allozyme analyses revealed significant subfamily differences in the likelihood of exhibiting egg laying, egg cannibalism, and nursing behavior, as well as significant subfamily differences in drone production. There were no subfamily differences among the different types of laying workers collected from each colony, suggesting that discrepancies between subfamily biases in egg-laying behavior and drone production are not due to inadequate sampling of the laying worker population. Subfamily biases in drone brood production within a colony changed significantly with brood age. Laying workers had significantly more developed ovaries than either egg cannibals or nurses, establishing a physiological correlate for the observed behavioral genetic differences. These results suggest there is reproductive conflict among subfamilies and individuals within queenless colonies of honey bees. The implications of these results for the evolution of reproductive conflict, in both queenright and queenless contexts, are discussed.
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  • 36
    ISSN: 1617-4623
    Keywords: Cerulenin ; Saccharomyces cerevisiae ; Fatty acid synthase ; β-Ketoacyl synthase ; Drug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cerulenin, an antifungal antibiotic produced by Cephalosporium caerulens, is a potent inhibitor of fatty acid synthase in various organisms, including Saccharomyces cerevisiae. The antibiotic inhibits the enzyme by binding covalently to the active center cysteine of the condensing enzyme domain. We isolated 12 cerulenin-resistant mutants of S. cerevisiae following treatment with ethyl methanesulfonate. The mechanism of cerulenin resistance in one of the mutants, KNCR-1, was studied. Growth of the mutant was over 20 times more resistant to cerulenin than that of the wild-type strain. Tetrad analysis suggested that all mutants mapped at the same locus, FAS2, the gene encoding the α subunit of the fatty acid synthase. The isolated fatty acid synthase, purified from the mutant KNCR-1, was highly resistant to cerulenin. The cerulenin concentration causing 50% inhibition (IC50) of the enzyme activity was measured to be 400 μM, whereas the IC50 value was 15 μM for the enzyme isolated from the wild-type strain, indicating a 30-fold increase in resistance to cerulenin. The FAS2 gene was cloned from the mutant. Sequence replacement experiments suggested that an 0.8 kb EcoRV-HindIII fragment closely correlated with cerulenin resistance. Sequence analysis of this region revealed that the GGT codon encoding Gly-1257 of the FAS2 gene was altered to AGT in the mutant, resulting in the codon for Ser. Furthermore, a recombinant FAS2 gene, in which the 0.8 Kb EcoRV-HindIII fragment of the wild-type FAS2 gene was replaced with the same region from the mutant, when introduced into FAS2-defective S. cerevisiae complemented the FAS2 pheno-type and showed cerulenin resistance. These data indicate that one amino acid substitution (Gly → Ser) in the α subunit of fatty acid synthase is responsible for the cerulenin resistance of the mutant KNCR-1.
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  • 37
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcriptional regulation ; Chromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract GAL11 was first identified as a gene required for full expression of some galactose-inducible genes that are activated by GAL4, and it was subsequently shown to be necessary for full expression of another set of genes activated by RAP1/GRFl/TUF. Genetic analysis suggests that GAL11 functions as a coactivator, mediating the interaction of sequence-specific activators with basal transcription factors. To test this hypothesis, we first tried to identify functional domains by deletion analysis and found that the 866–910 region is indispensable for function. Using reporters bearing various upstream activating sequences (UAS) and different core promoter structures, we show that the involvement of GAL11 in transcriptional activation varies with the target promoter and the particular combination of cis elements. Gel electrophoresis in the presence of chloroquine shows that GAL11 affects the chromatin structure of a circular plasmid. Based on these findings, the role of GAL 11 in regulation of transcription, including an alteration in chromatin structure, is discussed.
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  • 38
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    Molecular genetics and genomics 244 (1994), S. 260-268 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Amino acid permeases ; Transport ; Tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2Δ1-Δ4) cause slow growth, whereas one disrupted allele (scm2Δ5) is lethal. Cells with both the scm2Δ1 and trp1-Δ101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2Δ1 or trp1-Δ101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.
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  • 39
    ISSN: 1617-4623
    Keywords: Drug sensitivity ; Saccharomyces cerevisiae ; Major facilitator superfamily ; Drug expulsion
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    Topics: Biology
    Notes: Abstract Several pleiotropic drug sensitivities have been described in yeast. Some involve the loss of putative drug efflux pumps analogous to mammalian P-glycoproteins, others are caused by defects in sterol synthesis resulting in higher plasma membrane permeability. We have constructed a Saccharomyces cerevisiae strain that exhibits a strong crystal violet-sensitive phenotype. By selecting cells of the supersensitive strain for normal sensitivity after transformation with a wild-type yeast genomic library, a complementing 10-kb DNA fragment was isolated, a 3.4-kb subfragment of which was sufficient for complementation. DNA sequence analysis revealed that the complementing fragment comprised the recently sequenced SGE1 gene, a partial multicopy suppressor of gal11 mutations. The supersensitive strain was found to be a sge1 null mutant. Overexpression of SGE1 on a high-copy-number plasmid increased the resistance of the supersensitive strain. Disruption of SGE1 in a wild-type strain increased the sensitivity of the strain. These features of the SGE1 phenotype, as well as sequence homologies of SGE1 at the amino acid level, confirm that the Sge1 protein is a member of the drug-resistance protein family within the major facilitator superfamily (MFS).
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  • 40
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcription factor ; Zinc finger ; Multidrug resistance
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract TheSaccharomyces cerevisiae PDR3 gene, located near the centromere of chromosome II, has been completely sequenced and characterised. Mutationspdr3-1 andpdr3-2, which confer resistance to several antibiotics can be complemented by a wild-type allele of the PDR3 gene. The sequence of the wild-typePDR3 gene revealed the presence of a long open reading frame capable of encoding a 976-amino acid protein. The protein contains a single Zn(II)2Cys6 binuclear-type zinc finger homologous to the DNA-binding motifs of other transcriptional activators from lower eukaryotes. Evidence that the PDR3 protein is a transcriptional activator was provided by demonstrating that DNA-bound LexA-PDR3 fusion proteins stimulate expression of a nearby promoter containing LexA binding sites. The use of LexA-PDR3 fusions revealed that the protein contains two activation domains, one localised near the N-terminal, cysteine-rich domain and the other localised at the C-terminus. The salient feature of the PDR3 protein is its similarity to the protein coded byPDR1, a gene responsible forpleiotropicdrugresistance. The two proteins show 36% amino acid identity over their entire length and their zinc finger DNA-binding domains are highly conserved. The fact that the absence of both PDR1 and PDR3 (simultaneous disruption of the two genes) enhances multidrug sensitivity strongly suggests that the two transcriptional factors have closely related functions.
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  • 41
    ISSN: 1617-4623
    Keywords: Nuclear suppressor gene ; Mitochondrial functions ; Glucose repression ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We previously isolated a nuclear 5.7 kb genomic fragment carrying the NAM7/UPF1 gene, which is able to suppress mitochondrial splicing deficiency when present in multiple copies. We show here that an immediately adjacent gene ISF1 (Increasing Suppression Factor) increases the efficiency of the NAM7/UPF1 suppressor activity. The ISF1 gene has been independently isolated as the MBR3 gene and comparison of the ISF1 predicted protein sequence with data libraries revealed a significant similarity with the MBRI yeast protein. The ISF1 and NAM7 genes are transcribed in the same direction, and RNase mapping allowed the precise location of their termini within the intergenic region to be determined. The ISF1 gene is not essential for cell viability or respiratory growth. However as for many mitochondrial genes, ISF1 expression is sensitive to fermentative repression; in contrast expression of the NAM7 gene is unaffected by glucose. We propose that ISF1 could influence the NAM7/UPF1 function, possibly at the level of mRNA turnover, thus modulating the expression of nuclear genes involved in mitochondrial biogenesis.
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  • 42
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Mitochondria ; Cytochrome b ; Complex II ; HAP2/3/4
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Computer-assisted structural analysis of the predicted product of the previously described open reading frame (ORF) YKL4 located on the left arm of chromosome XI of Saccharomyces cerevisiae revealed a high degree of similarity (〉50%) to bovine cytochrome b 560, the sdhC polypeptide of the Escherichia coli succinate dehydrogenase (SDH) complex and the protein specified by ORF137 located on the chloroplast DNA of Marchantia polymorpha. Disruption of the yeast gene severely impaired mitochondrial function, while Northern analysis showed it to be subject to catabolite repression. Deletion analysis of the CYB3 promoter identified a single HAP2/3/4-binding element that is necessary and sufficient for carbon source-dependent transcriptional regulation. These experiments also suggested the presence of additional, as yet unidentified, transcriptional control elements, both negative and positive. Taken together, these data lead us to conclude that the CYB3 gene encodes the yeast homolog of the bovine cytochrome b 560 component of complex II of the mitochondrial electron transport chain.
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  • 43
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; CYP1(HAP1) protein ; Electron transport ; Oxygen and heme regulation ; Trans regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract CYP1 determines the expression of several genes whose transcription is heme-dependent in yeast. It exerts regulatory functions even in the absence of heme, usually considered to be its effector. It mediates both positive and negative effects, depending on the target gene and on the redox state of the cell. In the presence of heme, it binds through a cysteine-rich domain in which a histidine residue occupies the position of the sixth and essential cysteine of the otherwise classical zinc cluster DNA-binding domain exemplified by GAL4. We constructed specific missense mutations in the potential CYP1 zinc cluster domain by site-directed mutagenesis and looked for regulatory effects of the mutated proteins under specific physiological conditions. We show that CYP1 does belong to the zinc cluster regulatory family since a sixth essential cysteine residue is indeed present, albeit at a modified position when compared to the consensus sequence. We also show that the amino acid preceding the first cysteine residue of the DNA-binding domain critically affects the efficiency of regulation both in the presence and in the absence of heme: mutations known to affect DNA binding under heme-sufficient conditions also affect regulation under heme-deficient conditions. We therefore surmise that regulation under hemedeficient conditions is dependent upon DNA binding.
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  • 44
    ISSN: 1617-4623
    Keywords: Multicopy suppressors ; HAP2/3/4 activation complex ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Two new yeast genes, named MBR1 and MBR3, were isolated as multicopy suppressors of the growth defect of a strain lacking the HAP2 transcriptional activator. Both genes when overexpressed can also suppress the growth defect of hap3 and hap4 null mutants. However, overexpression of MBRI cannot substitute for the HAP2/3/4 complex in activation of the CYC1 gene. Nucleotide sequencing of MBR1 and MBR3 revealed that these two genes encode serine-rich, hydrophilic proteins with regions of significant homology. The functional importance of one of these conserved regions was shown by mutagenesis. Disruption of MBR1 leads to a partial growth defect on glycerol medium. Disruption of MBR3 has no major effect but the double disruptant shows a synthetic phenotype suggesting that the MBR1 and MBR3 gene products participate in common function.
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  • 45
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Meiosis Sporulation ; Divergent promoter ; Developmental regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Promoters that control gene expression in Saccharomyces cerevisiae only in a sporulation-specific manner have previously been isolated from a genomic yeast DNA library fused to a promoterless Escherichia coli lacZ gene. Two novel sporulation-specific genes, SPS18 and SPS19, were isolated using this technique. These genes are divergently controlled by the same promoter but with SPS18 expressed at four times the level of SPS19. Deletion analysis has shown that the promoter elements that exert sporulation control on each of the genes overlap, having a common 25 bp sequence located within the intergenic region. SPS18 encodes a 34-KDa protein of 300 amino acids that contains a putative zinc-binding domain and a region of highly basic residues that could target the protein to the nucleus. SPS19 encodes a 31-KDa protein of 295 amino acids, which has a peroxisomal targeting signal (SKL) at its C terminus; this protein belongs to the family of non-metallo short-chain alcohol dehydrogenases. A null mutation deleting the intergenic promoter prevented expression of both genes, and when homozygous in diploids, reduced the extent of sporulation four-fold; the spores that did form were viable, but failed to become resistant to ether, and were more sensitive to lytic enzymes. This phenotype reflects a defect in spore wall maturation, indicating that the product of at least one of the genes functions during the process of spore wall formation. Therefore these genes belong to the class of late sporulation-specific genes that are sequentially activated during the process of meiosis and spore formation.
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  • 46
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Duplicate genes ; Synthetic lethal mutants ; CTP synthetase ; Pyrimidine biosynthetic pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the pyrimidine biosynthetic pathway, CTP synthetase catalyses the conversion of uridine 5′-triphosphate (UTP) to cytidine 5′-triphosphate (CTP). In the yeast Saccharomyces cerevisiae, the URA7 gene encoding this enzyme was previously shown to be nonessential for cell viability. The present paper describes the selection of synthetic lethal mutants in the CTP biosynthetic pathway that led us to clone a second gene, named URA8, which also encodes a CTP synthetase. Comparison of the predicted amino acid sequences of the products of URA7 and URA8 shows 78% identity. Deletion of the URA8 gene is viable in a haploid strain but simultaneous presence of null alleles both URA7 and URA8 is lethal. Based on the codon bias values for the two genes and the intracellular concentrations of CTP in strains deleted for one of the two genes, relative to the wild-type level, URA7 appears to be the major gene for CTP biosynthesis. Nevertheless, URA8 alone also allows yeast growth, at least under standard laboratory conditions.
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  • 47
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    Molecular genetics and genomics 242 (1994), S. 517-527 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; HSP82 ; Random in vitro mutagenesis ; Temperature-sensitive mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The budding yeast Saccharomyces cerevisiae has two HSP90-related genes per haploid genome, HSP82 and HSC82. Random mutations were induced in vitro in the HSP82 gene by treatment of the plasmid with hydroxylamine. Four temperature-sensitive (ts) mutants and one simultaneously is and cold-sensitivie (cs) mutant were then selected in a yeast strain in which HSC82 had previously been disrupted. The mutants were found to have single base changes in the coding region, which caused single amino acid substitutions in the HSP82 protein. All of these mutations occurred in amino acid residues that are well conserved among HSP90-related proteins of various species from Escherichia coli to human. Various properties including cell morphology, macromolecular syntheses and thermosensitivity were examined in each mutant at both the permissive and nonpermissive temperatures. The mutations in HSP82 caused pleiotropic effects on these properties although the phenotypes exhibited at the nonpermissive temperature varied among the mutants.
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  • 48
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Cell wall ; Protein kinase C ; β-Glucanase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To obtain more information about the cell wall organization of Saccharomyces cerevisiae, we have developed a novel screening system to obtain cell wall-defective mutants, using a density gradient centrifugation method. Nine hypo-osmolarity-sensitive mutants were classified into two complementation groups, hpo1 and hpo2. Phase contrast microscopic observation showed that mutant cells bearing lesions at either locus became abnormally large. A gene that complemented the mutant phenotype of hpo2 was cloned and sequenced. This gene turned out to be identical to PKC1, which encodes the yeast homologue of mammalian protein kinase C. Complementation tests with pkc1Δ showed that hpo2 is allelic to pkc1. To study the reason for the fragility of hpo2 cells, cell wall was isolated and the glucan was analyzed. The amount of alkali, acid-insoluble glucan, which is responsible for the rigidity of the cell wall, was reduced to about 30% that of the wild-type cell and this may be the major cause of the fragility of the hpo2 mutant cell. Analysis of total wall proteins in hpo2 mutant cells on SDS-polyacrylamide gels revealed that a 33 kDa protein was overproduced two- to threefold relative to the wild-type level. This 33 kDa protein was identified as a β-glucanase, encoded by BGL2. Disruption of BGL2 in the hpo2 mutant partially rescued the growth rate defect. This suggests that the PKC1 kinase cascade regulates BGL2 expression negatively and overproduction of the β-glucanase is partially responsible for the growth defect. Since the bgl2 disruption did not rescue the hypo-osmolarty-sensitive phenotype of the hpo2 mutant, PKC1 must negatively regulate other enzymes involved in the biosynthesis and metabolism of the cell wall.
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  • 49
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    Molecular genetics and genomics 243 (1994), S. 358-362 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Oxidative stress ; High temperature viability ; Ubiquitin
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    Topics: Biology
    Notes: Abstract UBI4, the polyubiquitin gene of Saccharomyces cerevisiae, is expressed at a low level in vegetative cells, yet induced strongly in response to starvation, cadmium, DNA-damaging agents and heat shock. UBI4 is also expressed at a higher basal level in cells growing by respiration as compared to glucose-repressed cells growing by fermentation. This higher UBI4 expression of respiratory cultures probably helps to counteract the greater oxidative stress of respiratory growth. The effects of inactivating UBI4 on high temperature viability are more marked with respiratory cultures. Also loss of UBI4 leads to a considerably increased rate of killing of respiring cells by hydrogen peroxide, whereas the same gene inactivation has relatively little effect on the peroxide sensitivity of cells in which mitochondrial functions are repressed. This is the first study to reveal that ubiquitin levels in cells can influence their ability to withstand oxidative stress.
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  • 50
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    Molecular genetics and genomics 243 (1994), S. 363-368 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Glycolysis ; Phosphoglucose isomerase ; Antisense ; Double-strand coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Open reading frames longer than 300 bases were observed in the antisense strands of the genes coding for the glycolytic enzymes phosphoglucose isomerase, phosphoglycerate mutase, pyruvate kinase and alcohol dehydrogenase I. The open reading frames on both strands are in codon register. It has been suggested that proteins coded in codon register by complementary DNA strands can bind to each other. Consequently, it was interesting to investigate whether the open reading frames in the antisense strands of glycolytic enzyme genes are functional. We used oligonucleotide-directed mutagenesis of the PGI1 phosphoglucose isomerase gene to introduce pairs of closely spaced base substitutions that resulted in stop codons in one strand and only silent replacements in the other. Introduction of the two stop codons into the PGI1 sense strand caused the same physiological defects as already observed for pgi1 deletion mutants. No detectable effects were caused by the two stop codons in the antisense strand. A deletion that removed a section from − 31 by to + 109 by of the PGI1 gene but left 83 bases of the 3′ region beyond the antisense open reading frame had the same phenotype as a deletion removing both reading frames. A similar pair of deletions of the PYK1 gene and its antisense reading frame showed identical defects. Our own Northern experiments and those reported by other authors using double-stranded probes detected only one transcript for each gene. These observations indicate that the antisense reading frames are not functional. On the other hand, evidence is provided to show that the rather long reading frames in the antisense strands of these glycolytic enzyme genes could arise from the strongly selective codon usage in highly expressed yeast genes, which reduces the frequency of stop codons in the antisense strand.
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  • 51
    ISSN: 1617-4623
    Keywords: Bacterio-opsin ; Expression ; Yeast ; Saccharomyces cerevisiae ; Membranes
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    Notes: Abstract The bop gene codes for the membrane protein bacterio-opsin (BO), which on binding all-trans-retinal, constitutes the light-driven proton pump bacteriorhodopsin (BR) in the archaebacterium Halobacterium salinarium The designation H. salinarium instead of the former designation H. halobium is used throughout this paper following the classification of Tindall (1992) . This gene was cloned in a yeast multi-copy vector and expressed in Saccharomyces cerevisiae under the control of the constitutive ADH1 promoter. Both the authentic gene and a modified form lacking the precursor sequence were expressed in yeast. Both proteins are incorporated into the membrane in S. cerevisiae. The presequence is thus not required for membrane targeting and insertion of the archaebacterial protein in budding yeast, or in the fission yeast Schizosaccharomyces pombe, as has been shown previously. However, in contrast to S. pombe transformants, which take on a reddish colour when all-trans-retinal is added to the culture medium as a result of the in vivo regeneration of the pigment, S. cerevisiae cells expressing BO do not take on a red colour. The precursor of BO is processed to a protein identical in size to the mature BO found in the purple membrane of Halobacterium. The efficiency of processing in S. cerevisiae is dependent on growth phase, as well as on the composition of the medium and on the strain used. The efficiency of processing of BR is reduced in S. pombe and in a retinal-deficient strain of H. salinarium, when retinal is present in the medium.
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  • 52
    ISSN: 1617-4623
    Keywords: Arabidopsis thaliana ; Saccharomyces cerevisiae ; Complementation ; Aspartate transcarbamylase ; Orotate phosphoribosyl transferase ; Orotidine-5′-phosphate decarboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Arabidopsis thaliana cDNA library was used to complement Saccharomyces cerevisiae pyrimidine auxotrophic mutants. Mutants in all but one (carbamylphosphate synthetase) of the six steps in the de novo pyrimidine biosynthetic pathway could be complemented. We report here the cloning, sequencing and computer analysis of two cDNAs encoding the aspartate transcarbamylase (ATCase; EC 2.1.3.2) and orotate phosphoribosyltransferase-orotidine-5′-phosphate decarboxylase (OPRTase-OMP-decase; EC 2.4.2.10, EC 4.1.1.23) enzymes. These results confirm the presence in A. thaliana of a bifunctional gene whose product catalyses the last two steps of the pyrimidine biosynthetic pathway, as previously suggested by biochemical studies. The ATCase encoding cDNA sequence (PYRB gene) shows an open reading frame (ORF) of 1173 by coding for 390 amino acids. The cDNA encoding OPRTase-OMPdecase (PYRE-F gene) shows an ORF of 1431 by coding for 476 amino acids. Computer analysis of the deduced amino acid sequences of both cDNAs shows the expected high similarity with the ATCase, ornithine transcarbamylase (OTCase; EC 2.1.3.3), OPRTase and OMPdecase families. This heterospecific cloning approach increases our understanding of the genetic organization and interspecific functional conservation of the pyrimidine biosynthetic pathway and underlines its usefulness as a model for evolutionary studies.
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  • 53
    ISSN: 1617-4623
    Keywords: HAP3 ; Saccharomyces cerevisiae ; Kluyveromyces lactis ; Zinc finger ; Carbon source regulation
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    Topics: Biology
    Notes: Abstract The Kluyveromyces lactis homologue of the Saccharomyces cerevisiae HAP3 gene was isolated by functional complementation of the respiratory-deficient phenotype of the S. cerevisiae hap3::HIS4 strain SHY40. The KlHAP3 gene encodes a protein of 205 amino acids, of which the central B-domain of 90 residues is highly homologous to HAP3 counterparts of S. cerevisiae and higher eukaryotes. The protein contains a novel 4-cysteine zinc-finger motif and we propose by analogy that all other homologous HAP3 proteins contain the same motif, with the position containing the third cysteine being occupied by a serine residue. In contrast to the situation in S. cerevisiae, disruption of the KlHAP3 gene in K. lactis does not result in a respiratory-deficient phenotype and the growth of the null strain is indistinguishable from wild type. There is also no effect on the expression of the carbon source-regulated KlCYC1 gene, suggesting either a different role for the HAP2/3/4 complex, or the existence of a different mechanism of carbon source regulation. Sequence verification of the S. cerevisiae HAP3 locus reveals that, just as in K. lactis, a long open reading frame (ORF) is present upstream of the HAP3 gene. These highly homologous ORFs are predicted to have at least eight membrane-spanning fragments, but do not show significant homology to any known sequence present in databases. The ScORFX gene is transcribed in the opposite direction to ScHAP3, but, in contrast to an earlier report by Hahn et al. (1988), the transcripts of the two genes do not overlap. The model proposed by these authors, in which the ScHAP3 gene is regulated by an anti-sense non-coding mRNA, is therefore not correct.
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  • 54
    ISSN: 1617-4623
    Keywords: Gene regulation ; Ribozyme ; npt-gene ; Transgenic tobacco ; Genetics
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    Topics: Biology
    Notes: Abstract A chimeric gene encoding a ribozyme under the control of the cauliflower mosaic virus (CaMV) 35S promoter was introduced into transgenic tobacco plants. In vivo activity of this ribozyme, which was designed to cleave npt mRNA, was previously demonstrated by transient expression assays in plant protoplasts. The ribozyme gene was transferred into transgenic tobacco plants expressing an rbcS-npt chimeric gene as an indicator. Five double transformants out of sixteen exhibited a reduction in the amount of active NPT enzyme. To measure the amount of ribozyme produced, in the absence of its target, the ribozyme and target genes were separated by genetic segregation. The steady-state concentrations of ribozyme and target RNA were shown to be similar in the resulting single transformants. Direct evidence for a correlation between reduced npt gene expression and ribozyme expression was provided by crossing a plant containing only the ribozyme gene with a transgenic plant expressing the npt gene under control of the 35S promoter, i.e. the same promoter used to direct ribozyme expression. The expression of npt was reduced in all progeny containing both transgenes. Both steady-state levels of npt mRNA and amounts of active NPT enzyme are decreased. In addition, our data indicate that, at least in stable transformants, a large excess of ribozyme over target is not a prerequisite for achieving a significant reduction in target gene expression.
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  • 55
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    Molecular genetics and genomics 245 (1994), S. 686-693 
    ISSN: 1617-4623
    Keywords: Yeast ; Saccharomyces cerevisiae ; Poly(ADP-ribose) polymerase ; DNA repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coding sequence for human poly(ADP-ribose) polymerase was expressed inducibly in Saccharomyces cerevisiae from a low-copy-number plasmid vector. Cell free extracts of induced cells had poly(ADPribose) polymerase activity when assayed under standard conditions; activity could not be detected in non-induced cell extracts. Induced cells formed poly(ADP-ribose) in vivo, and levels of these polymers increased when cells were treated with the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). The cytotoxicity of this agent was increased in induced cells, and in vivo labelling with [3H]adenine further decreased their viability. Increased levels of poly(ADP-ribose) found in cells treated with the alkylating agent were not accompanied by lowering of the NAD concentration.
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  • 56
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; ts mutant ; Recovery ; HTR1 ; MCS1/SSD1
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    Notes: Abstract A new temperature-sensitive mutant of Saccharomyces cerevisiae was isolated. Arrested cells grown at the nonpermissive temperature were of dumb-bell shape and contained large vacuoles. A DNA fragment was cloned based on its ability to complement this temperature sensitivity. The HTR1 gene encodes a putative protein of 93 kDa without significant homology to any known proteins. The gene was mapped between ade5 and lys5 on the left arm of chromosome VII. The phenotype of the gene disruptant appeared to be strain-specific; disruption of the gene in strain W303 caused the cells to become temperature sensitive. The arrested phenotype here was similar to that of the original is mutant and cells in G2/M phase predominated at high temperature. Another disruptant in a strain YPH background grew slowly at high temperature due to slow progression through G2/M phase, and morphologically abnormal (elongated) cells accumulated. A single-copy suppressor that alleviated the temperature-sensitive defects in both strains was identified as MCS1/SSD1. The wild-type strains W303 and YPH are known to carry defective MCS1/SSD1 alleles; hence HTR1 may function redundantly with MCS1/SSD1 to suppress the temperature-sensitive phenotypes. In addition, based on a halo bioassay, the disruptant strains appeared to be defective in recovery from, or adaptive response to G1 arrest mediated by mating pheromone, even at the permissive temperature. Thus the gene has at least two functions and is designated HTR1 (required for high temperature growth and recovery from G1 arrest induced by mating pheromone).
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  • 57
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Cell cycle ; Bud site selection ; Guanine exchange factor ; Ras
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Guanine Exchange Factor (GEF) activity for Ras proteins has been associated with a conserved domain in Cdc25p, Sdc25p in Saccharomyces cerevisiae and several other proteins recently found in other eukaryotes. We have assessed the structure-function relationships between three different members of this family in S. cerevisiae, Cdc25p, Sdc25p and Bud5p. Cdc25p controls the Ras pathway, whereas Bud5p controls bud site localization. We demonstrate that the GEF domain of Sdc25p is closely related to that of Cdc25p. We first constructed a thermosensitive allele of SDC25 by specifically altering amino acid positions known to be changed in the cdc25-1 mutation. Secondly, we constructed three chimeric genes from CDC25 and SDC25, the products of which are as active in the Ras pathway as are the wild-type proteins. In contrast, similar chimeras made between CDC25 and BUD5 lead to proteins that are inactive both in the Ras and budding control pathways. This difference in the ability of chimeric proteins to retain activity allows us to define two subclasses of structurally different GEFs: Cdc25p and Sdc25p are Ras-specific GEFs, and Bud5p is a putative GEF for the Rsr1/Bud1 Rap-like protein.
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  • 58
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    Molecular genetics and genomics 245 (1994), S. 323-333 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; mRNA decay Poly(A) tail ; Ty transposition ; SSM4 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Decay rates of mRNAs depend on many elements and among these, the role of the poly(A) tail is now well established. In the yeast Saccharomyces cerevisiae, thermosensitive mutations in two genes, RNA14 and RNA15, result in mRNAs having shorter poly(A) tails and reduced half-life. To identify other components interacting in the same process, we have used a genetic approach to isolate mutations that suppress the thermosensitivity of an rna14 mutant strain. Mutations in a single locus, named SSM4, not only suppress the cell growth phenotype but also the mRNA instability and extend the short mRNA poly(A) tails. The frequency of appearance and the recessive nature of these mutations suggested that the suppressor effect was probably due to a loss of function. We failed to clone the SSM4 gene directly by complementation, owing to its absence from gene banks; it later emerged that the gene is toxic to Escherichia coli, but we have nevertheless been able to clone the SSM4 sequence by Ty element transposition tagging. Disruption of the SSM4 gene does not affect cell viability and suppresses the rna14 mutant phenotypes. The protein encoded by the SSM4 gene has a calculated molecular mass of 151 kDa and does not contain any known motif or show homology with known proteins. The toxicity of the SSM4 gene in E. coli suggests that a direct biochemical activity is associated with the corresponding protein.
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  • 59
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    Molecular genetics and genomics 242 (1994), S. 257-262 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Protein phosphatase ; Ras-cAMP pathway ; DIS2S1
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    Topics: Biology
    Notes: Abstract The Saccharomyces cerevisiae DIS2S1/GLC7 gene encodes a type 1 protein phosphatase indispensable for cell proliferation. We found that introduction of a multicopy DIS2S1 plasmid impaired growth of cells with reduced activity of the cAMP-dependent protein kinase. In order to understand further the interaction between the two enzymes, a temperature-sensitive mutation in the DIS2S1 gene was isolated. The mutant accumulated less glycogen than wild type at the permissive temperature, indicating that activity of the Dis2s1 protein phosphatase is attenuated by the mutation. Furthermore, the dis2s1 ts mutation was shown to be suppressed by a multicopy plasmid harboring PDE2, a gene for cAMP phosphodiesterase. These results indicate that the Ras-cAMP pathway interacts genetically with the DIS2S1/GLC7 gene.
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  • 60
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcriptional activator ; AP-1 ; Stress response
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The Saccharomyces cerevisiae YAP2 gene encoding an AP-1-like transcriptional activator protein was cloned by selection for genes that confer pleiotropic drug resistance when present in high copy number. The novel YAP2 gene encodes a protein of 45827 daltons and is homologous in part to a known transcriptional activator protein encoded by YAP1/PDR4/SNQ3/PAR1. Homology was found only in both terminal regions. The N-terminal portion contains a region rich in basic amino acids, followed by a “leucine zipper” motif. Overexpression of YAP2 led to the induction of expression of an AP-1 recognition element (ARE)-dependent promoter. The yap1 disruptant has been shown to be sensitive to H2O2. In this study, we demonstrated that the yap1 disruptant is also unable to grow in medium containing 150 μM cadmium, whereas the yap2 disruptant exhibited no significant phenotypes. However, YAP2 in high copy number did suppress cadmium sensitivity, but not H2O2 sensitivity of the yap1 disruptant. YAP1 was able to mediate both cadmium- and H2O2-induced transcriptional activation of an ARE-dependent promoter. A high-copy-number plasmid bearing YAP2 mediated cadmium-induced transcriptional activation of this promoter. The inductions were prevented by the antioxidant N-acetyl-l-cysteine.
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  • 61
    ISSN: 1617-4623
    Keywords: DNA polymerases ε and δ ; 3′ → 5′ Exonuclease ; Replication errors ; Spontaneous mutations ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA polymerases II (ε) and III(δ) are the only nuclear DNA polymerases known to possess an intrinsic 3′ → 5′ exonuclease in Saccharomyces cerevisiae. We have investigated the spontaneous mutator phenotypes of DNA polymerase δ and ε 3′ → 5′ exonuclease-deficient mutants, pol3-01 and pol2-4, respectively. pol3-01 and pol2-4 increased spontaneous mutation rates by factors of the order of 102 and 101, respectively, measured as URA3 forward mutation and his7-2 reversion. Surprisingly, a double mutant pol2-4 pol3-01 haploid was inviable. This was probably due to accumulation of unedited errors, since a pol2-4/pol2-4 pol3-01/pol3-01 diploid was viable, with the spontaneous his7-2 reversion rate increased by about 2 × 103-fold. Analysis of mutation rates of double mutants indicated that the 3′ → 5′ exonucleases of DNA polymerases δ and ε can act competitively and that, like the 3′ → 5′ exonuclease of DNA polymerase δ the 3′ → 5′ exonuclease of DNA polymerase ε acts in series with the PMS1 mismatch correction system. Mutational spectra at a URA3 gene placed in both orientations near to a defined replication origin provided evidence that the 3′ → 5′ exonucleases of DNA polymerases δ and ε act on opposite DNA strands, but were in sufficient to distinguish conclusively between different models of DNA replication.
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  • 62
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    Molecular genetics and genomics 243 (1994), S. 253-260 
    ISSN: 1617-4623
    Keywords: Recombinant DNA ; Saccharomyces cerevisiae ; Endo-β-glucanase ; Endo-xylanase ; Heterologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed a method for fast and efficient isolation of enzyme genes from filamentous fungi by combining the ability of Saccharomyces cerevisiae to express heterologous genes with the utilisation of sensitive and reliable enzyme assays. A cDNA library from the fungus Humicola insolens was constructed in a S. cerevisiae/Escherichia coli shuttle vector in E. coli. Sub-pools of the library were subsequently screened for enzyme activity in S. cerevisiae. More than 130 clones were identified as positive in either an endo-β-glucanase or an endo-xylanase assay. Based on a partial characterization of the DNA sequence of the individual clones, they could be grouped into five distinct types of endo-β-glucanases and three types of endo-xylanases. A representative cDNA from each type was sub-cloned in an Aspergillus vector and expressed in A. oryzae. The new cloning method may be an important alternative to traditional cloning methods based on amino acid sequence information.
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  • 63
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    Molecular genetics and genomics 243 (1994), S. 308-314 
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Integrative plasmids ; Recombinational structures ; UV irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of UV-induced pre-recombinational structures was studied using transformation of Saccharomyces cerevisiae cells with non-replicative plasmids. Transformation by double-stranded plasmids irradiated with UV was stimulated up to 50-fold, and both plasmid integration and conversion of the mutated chromosomal selective gene were found to be equally increased. The stimulation observed with such ‘totally’ irradiated plasmids was not found with plasmids bearing lesions in only one strand. This effect is attributed to the formation by excision repair of recombinogenic structures consisting of a pyrimidine dimer opposite a gap. When single-stranded integrative plasmids were irradiated, their transforming potential was decreased but the proportion of transformants that arose by gene conversion, rather than by plasmid integration, was increased from 8% to 49% as a function of the UV dose. Possible reasons why single-strand UV lesions favour gene conversion are discussed.
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  • 64
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Yeast Catabolite repression ; Gene expression
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    Topics: Biology
    Notes: Abstract Maltose utilization in yeast requires the presence of any one of the five unlinked, homologous MAL loci. Transcription of the two structural genes MALT (permease) and MALS (maltase) is induced by maltose and catabolite-repressed by glucose. MAL6T and MAL6S share a common 5′ intergenic sequence; deletion studies within this sequence revealed a bi-directionally functioning upstream activation sequence (UASM) consisting of four 11bp homologous sites. Activation of these sites by the MALR protein results in the coordinate expression of MAL6T and MAL6S. The basal promoter activates MALS expression to a greater extent than MALT and is located in a region that overlaps UASM. Deletion of several subsites within the UASM has an asymmetric effect on MAL gene expression, having a greater affect on MALT than on MALS. Catabolite repression of MAL6T and MAL6S by glucose is controlled at several levels. Using disruption mutants, the positively acting MAL1R protein was also found to play a role in catabolite repression of MAL6T and MAL6S.
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  • 65
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; RPK1 gene ; Protein kinase ; DNA replication ; Initiation of mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the sequence of RPK1 (for Regulatory cell Proliferation Kinase), a new Saccharomyces cerevisiae gene coding for a protein with sequence similarities to serine/threonine protein kinases. The protein sequence of 764 amino acids includes an amino-terminal domain (residues 1–410), which may be involved in regulation of the kinase domain (residues 411–764). The catalytic domain of Rpkl is not closely related to other known yeast protein kinases but exhibits strong homology to a newly discovered group of mammalian kinases (PYT, TTK, esk) with serine/threonine/tyrosine kinase activity. Null alleles of RPK1 are lethal and thus this gene belongs to the small group of yeast protein kinase genes that are essential for cell growth. In addition, eliminating the expression of RPK1 gives rise to the accumulation of non-viable cells with less than a 1 N DNA content suggesting that cells proceed into mitosis without completion of DNA synthesis. Therefore, the Rpkt kinase may function in a checkpoint control which couples DNA replication to mitosis. The level of the RPK1 transcript is extremely low and constant throughout the mitotic cycle. However it is regulated during cellular differentiation, being decreased in α-factor-treated a cells and increased late in meiosis in a/α diploids. Taken together, our results suggest that Rpk1 is involved in a pathway that coordinates cell proliferation and differentiation.
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  • 66
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    World journal of microbiology and biotechnology 10 (1994), S. 572-575 
    ISSN: 1573-0972
    Keywords: Growth inhibition ; L-lysine ε-aminotransferase ; nitrogen limitation ; α-oxoadipic acid ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lysine added to grain mashes under nitrogen-limiting conditions (as in most industrial fermentations) inhibited growth of Saccharomyces cerevisiae. This inhibition was relieved by raising the assimilable nitrogen content. Lysine-induced inhibition is not mediated through accumulation of α-oxoadipic acid, an intermediate of lysine metabolism which accumulates by a back up of intermediates in de novo synthesis. Lysine degradation is regulated by the synthesis of L-lysine ε-aminotransferase, an enzyme that catalyses the first step in one of three possible routes of lysine degradation (not previously reported in S. cerevisiae). Synthesis is repressed under nitrogenlimiting conditions, but derepressed when excess assimilable nitrogen is available. Derepression results in degradation of lysine and decreases inhibitory effects on growth. The toxic compound appears to be lysine itself.
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  • 67
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    Biotechnology and Bioengineering 43 (1994), S. 1094-1101 
    ISSN: 0006-3592
    Keywords: crossflow filtration ; microfiltration ; Saccharomyces cerevisiae ; molasses ; backwashing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A broth of yeast cells cultivated in molasses was crossfiltered with a thin-channel module. The permeation flux gradually decreased at a constant cell concentration. The flux was much lower than that obtained for yeast broth cultivated in yeast extract, polypeptone, and dextrose (YPD) medium during the filtration. The flux did not depend on the membrane pore size (0.45 to 5 μm). The steady-state flux was one-twentieth that calculated for a cake filtration mode from the amount of cake per unit filtration area and the specific resistance of the cake measured in a dead-end filtration apparatus. The lower flux was due to small particles (most of which were less than 1 μm in diameter) in the molasses. The mehanism of crossflow filtration of broths of yeast cells cultivated in molasses was clarified by analysis of the change in flux with time and observations with scanning electron microscopy. At the initial stage of crossflow filtration the yeast cells and particles from the molasses were deposited on the membrane to form the molasses were deposited on the membrane to form a cake in a similar way to dead-end filtration. After the deposition of cells onto the membrane ceased, the fine particles from molasses formed a thin layer, which had higher resistance than the cake formed next to the membrane. The backwashing method was effective to increase the flux. The flux increased low when the pore size was 0.45 to 0.08 μm, but using larger pores of 3 to 5 μm it returned almost to the bases line. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 43 (1994), S. 189-194 
    ISSN: 0006-3592
    Keywords: ethanol ; Saccharomyces cerevisiae ; carob pod ; fed-batch culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of ethanol from carob pod extract by free and immobilized Saccharomyces cerevisiae cells in batch and fed-batch culture was investigated. Fed-batch culture proved to be a better fermentation system for the production of ethanol than batch culture. In fed-batch culture, both free and immobilized S. cerevisiae cells gave the same maximum concentration (62 g/L) of final ethanol at an initial sugar concentration of 300 g/L and F = 167 mL/h. The maximum ethanol productivity (4.4 g/L h) was obtained with both free and immobilized cells at a substrate concentration of 300 g/L and F = 334 mL/h. In repeated fed-batch culture, immobilized S. cerevisiae cells gave a higher overall ethanol concentration compared with the free cells. The immobilized S. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 10 days. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 29-37 
    ISSN: 0006-3592
    Keywords: proteins, contaminant ; Escherichia coli ; Saccharomyces cerevisiae ; mammalian cell culture ; PAGE ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The protein components of three industrial recombinant expression systems: Escherichia coli, Saccharomyces cerevisiae, and a mammalian cell culture supernatant of CHO cells were characterized in terms of their molecular weight, isoelectric point, and relative surface hydrophobicity. Identification of individual proteins was done by reference to their position in protein band profiles by polyacrylamide gel electrophoresis (PAGE) of the crude material. This permitted a rapid and facile assignment of quantitative values for these three parameters to all the major protein components in these materials. Because it is the indigenous proteins in expression systems that will form the bulk of any impurities in the product, once the values of these parameters are known for any target recombinant protein, the data obtained will enable appropriate expression systems to be chosen for minimizing amounts of potential contaminants and reducing downstream processing requirements and costs. The data will also indicate which fractionation steps (i.e., charge, size or hydrophobicity-based) are likely to be best for distinguishing between target and contaminant proteins, thus aiding and early removal of the maximum quantities of undesired protein to bring subsequent bioseparation steps down in scale and cost and up in terms of efficiency. © 1994 John Wiley & Sons, Inc.
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  • 70
    ISSN: 0006-3592
    Keywords: oxygen profiles ; oxygen microprobe ; Po2-microelectrode ; artifacts ; alginate beads ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Polarographic microcoaxial needle electrodes were used to measure internal profiles of dissolved oxygen tension (Po2) within single Ca-alginate beads of different diameter containing entrapped cells of Saccharomyces cerevisiae. For the investigations, single beads coming from variable growing conditions and distinct cultivation stages were fixed in a special holding device. In dependence on microbial growth steep oxygen gradients were observed. The Oxygen penetration depth at steady state lay between 50 and 100 μm. After 8 h of cultivation time, the anaerobic space within the beads (φ 2 mm; cultivation in a packed bed reactor) is beginning at ∼ 130 μm, whereas the anaerobic space within the beads (φ 2 mm) coming from the shaker flask culture is located ∼440 μm below the bead surface. Surprisingly, steep gradients were also observed, when recording profiles from cell-free Ca-alginate beads of different diameter and alginate concentrations. The steep oxygen gradients apparently had to be interpreted as pseudo-Po2-gradients. These results were borne by several effects, such as formation of artifacts and diffusion barriers in front of the electrode tip or oxygen “availability” at the tip and consumption of oxygen by the electrode itself. These phenomena could be documented by microscopic observation and photography. Thus, to obtain real Po2-profiles it is important to be exactly informed about the physical, chemical, and biological properties of the material to be investigated. Furthermore, it is necessary to apply a special stepwise puncture technique with distinct step-in/step-out movements of the electrode: e.g., unidirectional or contradirectional puncture techniques. © 1994 John Wiley & Sons, Inc.
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  • 71
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    Biotechnology and Bioengineering 44 (1994), S. 1362-1366 
    ISSN: 0006-3592
    Keywords: Saccharomyces cerevisiae ; bioaccumulation ; gel immobilization ; cross-flow microfiltration ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cross-flow microfiltration was shown to retain Saccharomyces cerevisiae biomass utilized for heavy metal bioaccumulation. The passage of metal-laden influent through a series of sequential bioaccumulation systems allowed for further reductions in the levels of copper, cadmium, and cobalt in the final effluent than that afforded by a single bioaccumulation process. Serial bioaccumulation systems also allowed for partial separation of metals from dual metal influents. More than one elemental metal cation could be accumulated simultaneously and in greater quantities than when a single metal was present in the effluent (Cu2+ 0.43 mmol, Cu2+ + Cd2+ 0.67 mmol, and Cu2+ + Co2+ 0.83 mmol/g yeast dry mass when the initial concentration of each of the metal species was 0.2 mmol·L-1). Co-accumulation of two different metal cations allowed higher total levels of bioaccumulation than found with a single metal. The flux rate was 2.9 × 102 L·h-2μm-2 using a polypropylene microfiltration membrane (0.1 μm pore size) at 25°C. © 1994 John Wiley & Sons, Inc.
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  • 72
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    Biotechnology and Bioengineering 44 (1994), S. 736-744 
    ISSN: 0006-3592
    Keywords: disruption kinetics ; Saccharomyces cerevisiae ; virus-like particles ; recombinant cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recombinant cells of Saccharomyces cerevisiae, expressing virus-like particles (Ty-VLPs), can be readily disrupted in a high pressure homogenizer and show identical disruption kinetics to the untransformed host strain. When the cells are freeze/thawed before disruption, they become about four times more resistant to homogenization. This effect increases with the number of freeze/thaw cycles, but is independent of the time the cells remain frozen. The freeze/thaw effect is observed with cells harvested during both the logarithmic and stationary phase of growth, and occurs with the untransformed host strain as well as the transformed one. Freeze/thawed cells are twice as resistant to disruption in the bead mill as fresh cells. © 1994 John Wiley & Sons, Inc.
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  • 73
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    Biotechnology and Bioengineering 43 (1994), S. 101-105 
    ISSN: 0006-3592
    Keywords: Aspergillus awamori ; glucoamylase ; kinetic ; thermostability ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Asn182 → Ala Aspergillus awamori glucoamylase expressed in Saccharomyces cerevisiae had a first-order thermodeactivation coefficient 40% that of wild-type glucoamylase at pH 4.5 between 60° and 65°C, caused by the elimination of an Asn - Gly sequence subject to deamidation and eventual chain breakage. Above 70°C, and at pHs 3.5 and 5.5, thermodeactivation coefficients of wild-type and mutant enzymes were roughly equal, because the fastest deactivation mechanism was no longer deamidation. The mutation had little effect on the enzyme's optimal pH for activity and subsite map, or on the glucose yield from starch dextrin hydrolysis. During enzyme production by yeast fermentation, highest cell densities and activities of wild-type and mutant glucoamylases were attained after a period of glucose starvation, followed by a second addition of glucose. © 1994 John Wiley & Sons, Inc.
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  • 74
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    Biotechnology and Bioengineering 44 (1994), S. 1217-1227 
    ISSN: 0006-3592
    Keywords: acetophenone ; phenethyl alcohol ; Saccharomyces cerevisiae ; diffusion coefficient ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The intrabead diffusion coefficients of acetophenone and phenethyl alcohol were measured at 30°C in the triphasic immobilized yeast-water-hexane system. Saccharomyces cerevisiae cells were deactivated with hydrochloric acid and entrapped in calcium-alginate beads. Measurements of dry cell loss during deactivation, shrinkage of the beads during deactivation and the final porosity of the beads were made for various cell loadings. Final concentrations of wet cells in the beads ranged from approximately 0.25 to 0.30 g/mL. Mass transfer in the hexane phase, external to the beads, was eliminated experimentally. The estimated error of 5% to 10% in the diffusion coefficients is within the experimental error associated with the bead method. The effect of significant sampling volumes on the diffusivities was estimated theoretically and accounted for experimentally. The intrabead concentration of acetophenone and phenethyl alcohol was 150 to 800 ppm. The deactivated cells were shown to be impervious to acetophenone so that the measured diffusivities are extracellular parameters. The cell volume fraction in the beads ranged from 0.70 to 0.90, significantly higher than previously reported data. The effective diffusion coefficients conform to the random pore model. No diffusional interaction between acetophenone and phenethyl alcohol was observed. The addition of 2 vol% ethanol or methanol slightly increased the diffusivities. The thermodynamic partition coefficients were measured in the bead-free water-organic system and found to be an order of magnitude lower than the values calculated from the analysis of the diffusion data for the organic-bead system, suggesting that bead-free equilibrium data cannot be used in triphasic systems. © 1994 John Wiley & Sons, Inc.
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  • 75
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    Biotechnology and Bioengineering 44 (1994), S. 1083-1088 
    ISSN: 0006-3592
    Keywords: chitosan ; crosslinking ; yeast immobilization ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new simple method for the preparation of chemically crosslinked chitosan beads is presented. It consists of the dropwise addition of 2-3% (w/v) low molecular weight chitosan solution containing 2% (w/v) glyoxal in 1% (w/v) tetrasodiumdiphosphate, pH 8.0. Immobilized viable baker's yeast (Saccharomyces cerevisiae) could be obtained via gel entrapment within the new beads when means preventing their direct contact with soluble chitosan were provided, “disguising” the cells until gelation and crosslinking were completed. Such means included cell suspension in castor oil or mixing with carboxymethyl-cellulose powder. Application of these means was shown to be necessary, as cells exposed to soluble chitosan immediately lost their viability and glycolytic activity. Yeast disguised in castor oil was also protected from bead reinforcement by glutaraldehyde treatment, significantly strengthening bead stability while operating under acidic conditions. This capability was demonstrated by continuous ethanol production by chitosan entrapped yeast. © 1994 John Wiley & Sons, Inc.
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  • 76
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    Developmental Genetics 15 (1994) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 77
    ISSN: 0192-253X
    Keywords: Evolution ; Drosophila ; promoter ; glucose dehydrogenase ; development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The tissue-specific expression patterns of glucose dehydrogenase (GLD) exhibit a high degree of inter specific variation in the adult reproductive tract among the species in the genus Drosophila. We chose to focus on the evolution of GLD expression and the evolution of the Gld promoter in seven closely related species in the mela-nogaster subgroup as a means of elucidating the relationship of changes in cis-acting regulatory elements in the Gld promoter region with changes in tissue-specific expression. Although little variation in tissue-specific patterns of GLD was found in nonreproductive tissues during development, a surprisingly high level of variation was observed in the expression of GLD in both developing and ma-ture reproductive organs. In some cases this variation is correlated with changes in sequence elements in the Gld promoter which were previously shown to direct tissue-specific expression in the reproductive tract. In particular D. teissieri adult males do not express GLD in their ejaculatory ducts, atypical of the melanogaster subgroup species. The Gld promoter region of D. teissieri specifically lacks all three of the TTAGA regulatory elements present in D. melanogaster. The TTAGA elements were previously shown to direct reporter gene expression to the ejaculatory duct. Together these data suggest the absence or presence of the TTAGA elements may be responsible for variation in the absence or presence of GLD in the ejaculatory duct among species. © 1994 Wiley-Liss, Inc.
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  • 78
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    Developmental Genetics 15 (1994), S. 7-18 
    ISSN: 0192-253X
    Keywords: Tribolium ; engrailed ; embryogenesis ; segmentation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have cloned and sequenced the single Tribolium homolog of the Drosophila engrailed gene. The predicted protein contains a homeobox and several domains conserved among all engrailed genes identified to date. In addition it contains several features specific to the invected homologs of Bombyx and Drosophila, indicating that these features most likely were present in the ancestral gene in the common ancestor of holometabolous insects. We used the cross-reacting monoclonal antibody, 4D9, to follow the expression of the Engrailed protein during segmentation in Tribolium embryos. As in other insects, Engrailed accumulates in the nuclei of cells along the posterior margin of each segment. The first Engrailed stripe appears as the embryonic rudiment condenses. Then as the rudiment elongates into a germ band, Engrailed stripes appear in an anterior to posterior progression, just prior to morphological evidence of the formation of each segment. As in Drosophila (a long germ insect), expression of engrailed in Tribolium (classified as a short germ insect) is preceeded by the expression of several homologous segmentation genes, suggesting that similar genetic regulatory mechanisms are shared by diverse developmental types. © 1994 Wiley-Liss, Inc.
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  • 79
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    Developmental Genetics 15 (1994), S. 425-434 
    ISSN: 0192-253X
    Keywords: Polycomb group ; homeotic ; spalt ; devenir ; Su(Pc)37D ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: There are 11 Polycomb group genes known in Drosophila. These genes are negative regulators of homeotic gene expression, and may act by modifying chromatin structure. It is not clear how many members of the Polycomb group of genes exist. Many were discovered because of their homeotic phenotypes, or because they enhance homeotic mutations. Systematic screens for enhancers of Polycomb have identified previously known members of the Polycomb group. In an attempt to discover cytological locations of new Polycomb group genes, we crossed deletions uncovering about 20% of the genome to Polycomb-like and Polycomb and scored for enhancement of the extra sex combs phenotype. Haploidy for four regions, 36F7-37A, 43E18; 44B5-9, 70C2-6, and 70C6-15; 70D enhanced the extra sex comb phenotype associated with strong Polycomb group mutations. These regions have homeotic phenotypes either as homozygous embryos or heterozy-gous adults, or both. We also show that spalt enhances Polycomb group mutations. These results are discussed with respect to previous estimates of Polycomb group gene number. © 1994 Wiley-Liss, Inc.
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  • 80
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    Developmental Genetics 15 (1994), S. 435-442 
    ISSN: 0192-253X
    Keywords: Fertility ; sex-reversal ; XY ovary ; XY oocyte ; mouse ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: When the Y chromosome of a Mus musculus domesticus mouse strain is placed onto the C57BL/6J (B6) inbred background, the XY progeny develop ovaries or ovotestes but never normal testes during fetal life. While some of the hermaphroditic males become fertile, none of the XY females produces litters. Here, we examined the fertility and development of oocytes derived from the XY female mouse. With or without preceding injection of gonadotropins, female mice were mated with normal B6 males, and their embryos were recovered at various developmental stages. In vitro fertilization was performed with the eggs recovered from the oviduct after treatment with go-nadotropins. Development of embryos was examined by both light and electron microscopy. The results indicate that the oocytes released from the B6.YDOM ovary were efficiently fertilized and often initiated the first cell cleavage, but all embryos died during early preimplantation periods. Even when oocytes were fertilized in vitro, minimizing their exposure to the XY oviduct/uterus environment, most embryos died at the 1- or 2-cell stage. A few exceptional embryos reached the 4- or 8-cell stage, but abnormalities were evident in both nuclear and cytoplasmic structures of all embryos. After cleavage, neighbouring blastomeres were only loosely associated, and microvilli were abundant at the intercellular interfaces. We postulate that oocytes of the B.6.YDOM female mouse become defective during XY ovarian differentiation, and, hence, fail to proceed through normal embryonic development. © 1994 Wiley-Liss, Inc.
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  • 81
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    Developmental Genetics 15 (1994), S. 458-462 
    ISSN: 0192-253X
    Keywords: Epigenetic phenomena ; chromatin structure ; eukaryotes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the broadest terms, epigenetic phenomena in eukaryotes depend on the interaction of alleles or repeated sequences or on the mitotic inheritance of chromatin states or methylation patterns. One of the most exciting aspects of the study of epigenetic phenomena is the insight that can be gained into the structure and assembly of higher-order chromatin structures, an important subject that has proved refractory to current biochemical methodologies. Rapid progress in the study of gene inactivation in fungi, plants, and invertebrates will provide new hypotheses to be tested in mammals. © 1994 Wiley-Liss, Inc.
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  • 82
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    Developmental Genetics 15 (1994), S. 485-490 
    ISSN: 0192-253X
    Keywords: Pattern formation ; positional information ; periodic structures ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A widely used mechanism for pattern formation is based on positional information: cells acquire positional identities as in a coordinate system and then interpret this information according to their genetic constitution and developmental history. In Drosophila maternal factors establish the axes and set up a maternal system of positional information on which further patterning is built. There is a cascade of gene activity which leads both to the development of periodic structures, the segments, and to their acquiring a unique identity. This involves the binding of transcription factors to regulatory regions of genes to produce sharp thresholds. Many of the genes involved in these processes, particularly the Hox complex, are also involved in specifying the body axis and limbs of vertebrates. There are striking similarities in the mechanisms for spcifying and recording positional identity in Drosophila and vertebrates. © 1994 Wiley-Liss, Inc.
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  • 83
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    Developmental Genetics 15 (1994), S. 515-522 
    ISSN: 0192-253X
    Keywords: Genetic imprinting ; androgenesis ; parthenogenesis ; development ; chimeras ; Life and Medical Sciences ; Genetics
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  • 84
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    Developmental Genetics 15 (1994), S. 320-331 
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; ecdysone ; steroid ; Eip28/29 ; EcREs ; lacZ ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Eip28/29 gene of Drosophila is an example of a tissue- and stage-specific ecdysone-responsive gene. Its diverse patterns of expression during the third larval instar and a synopsis of those patterns in terms of expression groups have been reported previously. Here we have studied the expression (in transgenic flies) of reporter genes controlled by Eip28/29-derived flanking DNA. During the middle and late third instar, most tissues exhibit normal expression patterns when controlled by one of two classes of regulatory sequences. Class A sequences include only 657 Np of 5′ flanking DNA from Eip28/29. Class B sequences include an extended 3′ flanking region and a minimal (≤93 Np) 5′ flanking region. The class B sequences include all those elements known to be important for ecdvsone induction in cultured cells. They are sufficient to direct the normal premetamorphic induction of Eip28/29 in the lymph glands, hemocytes, proventriculus, and Malpighian tubules. This is consistent with our suggestion that Kc cells are derived from embryonic hematopoietic cells. It is remarkable that the epidermis requires only class A sequences. These are sufficient to up-regulate expression at medinstar and to down-regulate expression at metamorphosis. It follows that the epidermis uses EcREs distinct from those that function in Kc cells. It is possible that the Upstream EcRE, which is nearly silent in Kc cells, is active in the epidermis. © 1994 Wiley-Liss, Inc.
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  • 85
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    Yeast 10 (1994), S. 13-27 
    ISSN: 0749-503X
    Keywords: RAD3 ; helicase ; nucleotide excision repair ; mitotic recombination ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mutations rad3-101 and rad3-102 (formerly rem1-1 and rem1-2) of the essential RAD3 gene of Saccharomyces cerevisiae confer a phenotype of semidominant enhancement of spontaneous mitotic recombination and mutation frequencies, but not extreme sensitivity to ultraviolet (UV) light. These properties differ from the previously published observations of other rad3 mutations, which are very UV-sensitive but do not alter recombination frequencies significantly. We have located the position of DNA sequence changes from wild-type RAD3 to the rad3-101 and rad3-102 mutations and have demonstrated that these sequence changes are necessary and sufficient to confer the (Rem-) mutant phenotype when transferred into otherwise wild-type RAD3 plasmids. The Rem- mutations are not located in the same region. It is possible that the two regions of the gene in which these mutations map define portions of the molecule which are in contact when folded in the native configuration. To begin to test this hypothesis, we have constructed two double mutant alleles, one with rad3-101 and rad3-102, and one with the UV-sensitive rad3-1 mutation and rad3-102. We find that plasmids carrying these double mutant alleles of RAD3 are no longer able to confer a hyper-recombinational phenotype and do not complement the UV-sensitivity of the excision-defective rad3-2 allele. We conclude that the double mutant alleles are non-functional for excision repair, and may be null. We have also constructed new rad3 alleles by oligonucleotide-directed mutagenesis and have tested their effects on spontaneous mutation and mitotic recombination and on UV repair.
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  • 86
    ISSN: 0749-503X
    Keywords: Retrotransposon ; transcription ; Saccharomyces cerevisiae ; chromosome XI ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: SPT genes are suppressors of mutations induced by the retrotransposon Ty in Saccharomyces cerevisiae. All SPT genes isolated to date suppress Ty-induced mutations by altering transcription. SPT23 was identified as a multicopy suppressor of the Ty-induced promoter mutations his4-912δ and lys2-61. Multicopy expression of SPT23 suppresses a variety of Ty-induced promoter mutations, including the MAT-regulated alleles his4-917 (480) and lys2-173R2. Here, we report the initial characterization of the SPT23 gene, including its nucleotide sequence and location in the yeast genome. The SPT23 gene contains a 1854 base pair open reading frame. Searches of the current data bases show no homology between SPT23 and previously described genes or proteins. The SPT23 gene is located between RAM2 and MAK11 on the left arm of chromosome XI. Tn10-LUK insertional mutagenesis of the SPT23 gene indicates that SPT23 is not essential for vegetative growth and spt23 mutations do not confer an Spt- phenotype.
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  • 87
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; chromosome XI ; DNA-binding ; leucine zipper ; HMG box ; tRNAval. ; Kazal serine protease inhibitor signature ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the nucleotide sequence of an 11·7 kb fragment from the left arm of Saccharomyces cerevisiae chromosome XI. Analysis reveals a new tRNA for valine and four unknown open reading frames among which YKL245 shows homology with a yeast mitochondrial regulatory protein and YKL244, YKL246 and YKL247 are unknown.
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  • 88
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    Yeast 10 (1994) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
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  • 89
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    Yeast 10 (1994), S. 185-197 
    ISSN: 0749-503X
    Keywords: Yeast ; energy metabolism ; respiration ; fermentation ; metabolic flux ; aerobic chemostat culture ; model ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The pattern of energy metabolism of different types of yeasts (obligate aerobes and facultative anaerobes) in aerobic chemostat cultures has been evaluated and interpreted on the basis of a coupling of metabolic fluxes between glycolytic and oxidative components.A model has been formulated which defines glycolytic and oxidative subunits through which the substrate C-flux (gram-atom g-1 h-1) is calculated, stating that a relative imbalance between glycolytic flux and subsequent oxidative steps alone is sufficient to account for the onset of oxidoreductive metabolism in any type of yeast, irrespective of the maximum respiratory capacity. The model is able to reproduce the patterns of behaviour reported for the different types of yeasts, and the individual features of each strain are explained on the basis of metabolic differences which are defined by a set of normalized parameters. The model can be applied to different substrates and conditions, providing a methodological basis for more detailed studies of the steps controlling yeast energy metabolism.
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  • 90
    ISSN: 0749-503X
    Keywords: HEM2 ; promoter ; δ-aminolaevulinate dehydratase ; PBG synthetase ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This paper reports the 1890-bp sequence located upstream of the HEM2 gene of Saccharomyces cerevisiae. The following potential regulatory protein-binding motifs were found: ABF1-binding site, yAP1-binding site, two REB1-binding sites, a cyclic AMP-responsive element, RAP1-binding site, and several HAP2-HAP3-HAP4 binding sites, implicating a complex regulatory mechanism governing expression for the HEM2 gene.
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  • 91
    ISSN: 0749-503X
    Keywords: Genome sequencing ; Saccharomyces cerevisiae ; chromosome XI ; MBR1 ; GTPase-activating protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We present the DNA sequence analysis of a region covering a 3·5 kb EcoRI fragment from the left arm of chromosome XI from Saccharomyces cerevisiae. This region contains five open reading frames (ORFs) which code for proteins of greater than 100 amino acids. ORF YKL425 codes for the previously sequenced Mbr1 (Valens et al., 1991; Daignan-Fornier et al., 1993) which participates in mitochondrial biogenesis. YKL424 has identity with a GTPase-activating protein of higher eukaryotes. The three remaining ORFs have no identity to known proteins within the databases screened and are not assigned ORF numbers as they are completely contained with ORFs YKL424 and YKL425. This sequence has been entered in the EMBL Data Library under Accession Number X75561.
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  • 92
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    Yeast 10 (1994), S. 105-112 
    ISSN: 0749-503X
    Keywords: Cloning vectors ; Saccharomyces cerevisiae ; fusion proteins ; epitope tagging ; immunodetection ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In this paper are described a set of new high-copy-number yeast vectors, which are specially designed for the conditional expression of epitope-tagged proteins in vivo. One of the major advantages of these plasmids is that they allow polymerase chain reaction-amplified open reading frames to be automatically fused in frame with the epitope-coding sequence, avoiding longer procedures such as site-directed mutagenesis. This heterologous construction can be realized either at the 5′-end of the coding sequence, in the pYeF1 vector, or at its 3′-end, in pYeF2, generating N- or C-terminal tagged proteins, respectively. Moreover, to increase the usefulness of the method, derivatives of the two basic URA3-borne pYeF1 and pYeF2 were constructed, carrying either the HIS3 or TRP1 gene as a marker of selection. These vectors could be of use for the purpose of functional analysis of the newly discovered genes resulting from the systematic sequencing of the yeast genome. Here, we present results showing the functional expression and the efficient immunoprecipitation of the epitope-tagged Rna15 protein, which is involved in Saccharomyces cerevisiae mRNA stability.
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  • 93
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 151-157 
    ISSN: 0749-503X
    Keywords: Growth cycle ; mRNA ; Northern analysis ; pulse labeling ; ribosome synthesis ; r-protein ; rRNA ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have measured the content of ribosomes, the rate of synthesis of ribosomal RNA, and the level of the mRNA for ribosomal proteins as a culture of Saccharomyces cerevisiae passes through the growth cycle. The transcription of both ribosomal RNA and ribosomal protein genes disappears at an unexpectedly early stage in the growth cycle, accompanied by a decline in the total RNA content of the culture by nearly 50% and a decline in the number of ribosomes per cell to less than 25% of the maximum value. During this time the cells continue to grow through more than two doublings, initially at the normal log growth rate, which then decline gradually for several hours. The data suggest that the cell can sense an unfavorable change within the medium and responds by employing regulation of both synthesis and degradation of its ribosomes. We conclude that the cell regulates ribosome synthesis and content according to its estimate of the potential for growth.
    Additional Material: 3 Ill.
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  • 94
    ISSN: 0749-503X
    Keywords: PFK3 gene ; particulate phosphofructokinase ; nutrient stress ; thermal stress ; trehalose ; glycogen ; S. cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The pfk3 mutation of Saccharomyces cerevisiae causes glucose-negativity in a pfk1 genetic background, the mutant is temperature-sensitive for growth and homozygous diploids do not sporulate. It fails to accumulate trehalose, and has an altered glycogen accumulation profile under glucose-starvation conditions. pfk3-6, one of the alleles of pfk3, has an altered morphology, forming long chain-like structures at 36°C. The PFK3 gene was cloned by complementation of the mutant phenotypes. Integrative transformation demonstrated that the complementing fragment encoded the authentic PFK3 gene. The disruption of the gene does not affect viability. Like the EMS-induced pfk3 mutant, the disruptants are temperature-sensitive and in a pfk1 genetic background are also glucose-negative. The PFK3 transcript is induced by heat-shock. Partial DNA sequence shows that PFK3 is identical to TPS2 (De Virgilio et al., 1993). We demonstrate that, apart from being a structural determinant of trehalose 6-phosphate phosphatase, PFK3 (TPS2) is required for PFKII synthesis and normal regulation of S. cerevisiae response to nutrient and thermal stresses.
    Additional Material: 6 Ill.
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  • 95
    ISSN: 0749-503X
    Keywords: Genome sequencing ; Saccharomyces cerevisiae ; chromosome XI ; SMY1 ; pre-mRNA splicing factor ; ATPase subunit C ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the DNA sequence analysis of a region on the left arm of chromosome XI of Saccharomyces cerevisiae extending over 10 kb. The region contains five open reading frames (ORFs) of greater than 100 amino acids which do not show significant overlap with other ORFs. YKL408 contains a sequence with strong similarity to the RNA helicase pre-mRNA splicing factors PRP2, PRP16 and PRP22 (Burgess et al., 1990; Company et al., 1991; Ruby et al., 1991). YKL409 corresponds to the gene SMY1, the sequence of which was previously reported by Lillie and Brown (1992). YKL410 is identical to ATPase subunit C (Beltran et al., 1992) except for an N-terminal extension. YKL406 and YKL407 show no significant identity with any sequences in the databases searched. The sequence has been entered in the EMBL Data Library under Accession Number X75560.
    Additional Material: 4 Ill.
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 271-274 
    ISSN: 0749-503X
    Keywords: Genome sequencing ; Saccharomyces cerevisiae ; chromosome III ; telomeres ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A comparison of the sequences of telomere regions from several yeast chromosomes revealed an apparent cloning artifact for the right end of chromosome III. An integrating vector containing G1-3T telomere sequences was used to clone the right end of chromosome III from a strain related to S288C. The sequence of this clone confirmed that the published sequence was incorrect and demonstrated that the right telomere region of chromosome III is similar to other telomeres.
    Additional Material: 3 Ill.
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  • 97
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; Saccharomyces douglasii ; evolution ; ARG4 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A 3·6 kb DNA fragment from Saccharomyces douglasii, containing the ARG4 gene, has been cloned, sequenced and compared to the corresponding region from Saccharomyces cerevisiae. The organization of this region is identical in both yeasts. It contains besides the ARG4 gene, another complete open reading frame (ORF) (YSD83) and a third incomplete one (DED81). The ARG4 and the YSD83 coding regions differ from their S. cerevisiae homologs by 8.1% and 12·5%, respectively, of base substitutions. The encoded proteins have evolved differently: amino acid replacements are significantly less frequent in Arg4 (2·8%) than in Ysc83 (12·4%) and most of the changes in Arg4 are conservative, which is not the case for Ysc83. The non-coding regions are less conserved, with small AT-rich insertions/deletions and 20% base substitutions. However, the level of divergence is smaller in the aligned sequences of these regions than in silent sites of the ORFs, probably revealing a higher degree of constraints. The Gcn4 binding site and the region where meiotic double-strand breaks occur, are fully conserved. The data confirm that these two yeasts are evolutionarily closely related and that comparisons of their sequences might reveal conserved protein and DNA domains not expected to be found in sequence comparisons between more diverged organisms.
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 481-490 
    ISSN: 0749-503X
    Keywords: THI4 (MOL1) ; thiamine biosynthesis ; thiamine uptake ; regulation ; molasses ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: THI4, a Saccharomyces cerevisiae gene originally identified as a result of transient expression in molasses medium and named MOL1 is regulated by thiamine. Using a THI4 promoter-lacZ fusion on a centromeric yeast vector, we have shown that the THI4 is completely repressed throughout batch culture by thiamine at a concentration around 1 μM, but shows high level constitutive expression in thiamine-free medium. The transient expression pattern observed in molasses medium can be mimicked by the addition of 0·15 μM-thiamine to defined minimal medium. Cells grown in thiamine-free medium have an intracellular thiamine concentration of around 9 pmol/107 cells. A low level (1 μM) of exogenous thiamine is completely sequestered from the medium within 30 min; intracellular thiamine concentrations rise rapidly, followed by a gradual decrease as a result of dilution during growth. A saturating extracellular level of thiamine leads to a maximal intracellular concentration of around 1600 pmol/107 cells, at which point the transport system is shut down. After transfer from repressing to non-repressing medium, THI4 becomes induced when the intracellular concentration of thiamine falls to 20 pmol/107 cells. A thi4::UARA3 disruption strain is auxotrophic for thiamine, but can grow in the presence of hydroxyethyl thiazole, indicating that the gene product is involved in the biosynthetic pathway leading to the formation of the thiazole precursor of thiamine.
    Additional Material: 6 Ill.
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  • 99
    ISSN: 0749-503X
    Keywords: Ca2+ sensitive mutants ; cross-complementation ; Saccharomyces cerevisiae ; chromosome XII ; CCC1 ; calcium regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated, sequenced, mapped and disrupted a novel gene, CCC1, from Saccharomyces cerevisiae. This gene displays non-allelic complementation of the Ca2+-sensitive phenotype conferred by the csg1 mutation. The ability of this gene, in two copies per cell, to reverse the csg1 defect suggests it may have a role in regulating Ca2+ homeostasis. The sequence of CCC1 indicates that it encodes a 322 amino acid, membrane-associated protein. The CCC1 gene is located on the right arm of chromosome XII. The sequence has been deposited in the GenBank data library under Accession Number L24112.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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