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  • 1
    Electronic Resource
    Electronic Resource
    Measurements of electrical potential differences across yeast plasma membranes with microelectrodes are consistent with values from steady-state distribution of tetraphenylphosphonium inPichia humboldtii (1988)
    Springer
    The journal of membrane biology 103 (1988), S. 255-261 
    Details
    ISSN: 1432-1424
    Keywords: electrical potential difference (Δψ) ; membrane potential ; yeast electrophysiology ; microelectrode ; TPP+ distribution ; Pichia humboldtii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Electrical potential differences across the plasma membrane (Δψ) of the yeastPichia humboldtii were measured with microelectrodes (filled with 0.1m KCl) inserted into cells immobilized in microfunnels. The registered Δψ signals were reproducible and stable for several minutes. On attainment of stable reading for Δψ the specific membrane resistanceR sp was determined by applying square-current pulses to the preparation. Both Δψ andR sp were pH dependent and displayed equal but opposite deflection, Δψ reaching its maximal value of −88±9 mV (n=13) andR sp its minimal value of 10 kΩ·cm2 (maximal conductance) at pH 6.5. Uncouplers and the polyene antibiotic nystatin depolarized the cells, decreasing Δψ to −21±15 mV (n=10) with concomitant decrease ofR sp. Comparison of Δψ values from microelectrode measurements with those calculated from the steady-state distribution of tetraphenylphosphonium ions agreed within 10 mV under all physiological conditions tested, except at pH values above 7.0. During microelectrode insertion transient voltage signals (a few msec long) were detected by means of an oscilloscope. These voltage signals were superimposed on the stable Δψ recordings described above. These short voltage signals disappeared in uncoupled cells. The closely related Δψ values obtained by two independent methods (direct measurements with microelectrodes and calculation from steady-state distribution of a lipophilic cation) provide evidence that these values reffect the true membrane potential of intact cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01993985
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  • 2
    Electronic Resource
    Electronic Resource
    The SpTRK Gene Encodes a Potassium-specific Transport Protein TKHp in Schizosaccharomyces pombe (1996)
    Springer
    The journal of membrane biology 152 (1996), S. 169-181 
    Details
    ISSN: 1432-1424
    Keywords: Key words: K+ uptake system — Genetic complementation — Transport kinetics — Patch-clamp analysis — Ion-selectivity —Schizosaccharomyces pombe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Complementary DNAs involved in potassium transport in Schizosaccharomyces pombe were selected by complementation of defective K+ uptake in a trk1 trk2 mutant of Saccharomyces cerevisiae. Here we describe the SpTRK gene that encodes a protein of 833 amino acids. The predicted structure contains 12 putative membrane-spanning domains and resembles various high- and low-affinity systems for K+ transport in yeasts and plants. TKHp, the product of SpTRK exhibits high homology to TRK1 and TRK2 of Saccharomyces cerevisiae as well as to HKT1 of Triticum aestivum, but is not related to HAK1 of another ascomycete, Schwanniomyces occidentalis, suggesting that different routes for potassium uptake evolved independently. This protein is a potassium-specific transporter since functional analysis of the SpTRK complemented mutant strain of Sacch. cerevisiae revealed potassium transport affinities and uptake characteristics similar to those obtained in wild-type Sch. pombe. Patch-clamp analysis in the whole-cell mode confirmed the TKHp-mediated inward current in the complemented strain. The inward current increased by acidification of the extracellular medium thereby suggesting a mechanism of K+H+ cotransport. The inward current is not detectable when external K+ is substituted by Na+, documenting a distinct cation specificity of the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900095
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  • 3
    Electronic Resource
    Electronic Resource
    A nystatin-resistant mutant of Rhodotorula gracilis. Transport properties and sterol content (1982)
    Springer
    Archives of microbiology 132 (1982), S. 313-316 
    Details
    ISSN: 1432-072X
    Keywords: Rhodotorula gracilis ; Nystatin resistance ; Sterol content ; Plasma membrane permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A nystatin-resistant mutant of Rhodotorula gracilis was obtained by treatment of the wild strain cells with N-methyl-N-nitro-N-nitrosoguanidine and selected on agar plates containing 150 μg nystatin/ml. Three important transport functions of the plasma membrane of mutant cells: the accumulation of monosaccharides, the generation and maintenance of the pH-gradient and of the membrane potential, as well as the cell respiration were insensitive to at least 10-5 M nystatin. This concentration of nystatin inhibited completely all these processes in wild strain cells. Analysis of cellular sterols revealed a defect of ergosterol biosynthesis in the mutant, which was localized at the last oxidative step between 5,6-dihydroergosterol and ergosterol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413381
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  • 4
    Electronic Resource
    Electronic Resource
    Endogenous respiration reflects the energy load imposed by transport of nonmetabolizable substrates and by induced de novo protein synthesis in Rhodotorula glutinis (1993)
    Springer
    Archives of microbiology 159 (1993), S. 541-544 
    Details
    ISSN: 1432-072X
    Keywords: Substrate uptake ; Energy requirement ; Endogenous respiration ; Nonmetabolized substrate ; Induced catabolism ; Rhodotorula glutinis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uptake of the nonmetabolizable sugars 6-deoxy-d-glucose, l-rhamnose and l-xylose, which are taken up by a common carrier, stimulated significantly cell respiration in Rhodotorula glutinis. The extra oxygen consumption for uptake (0.5–0.7 equivalents O2/mol transported sugar) was proportional to the uptake rate and was independent of the K tvalue of the transport system. Sugars that become metabolized after induction, d-arabinose and methyl-α-d-glucoside, caused a higher stimulation, 1.4 and 3.6 equivalents O2/mol respectively, which was reduced to 0.6 equivalents O2/mol when de novo protein synthesis was blocked by cycloheximide. The stimulation of respiration thus includes a fraction related purely to the energy demand for uptake and another one related to the induced de novo protein synthesis. The net uptake-induced respiration boost was similar with all sugars under study irrespective of their transport systems. The estimated energy demand was equivalent to about 2 ATP/sugar molecule. For comparison, the amino acid analogue α-aminoisobutyric acid (AIB) was also investigated; the overall energy demand for its uptake corresponded to the equivalent of about 4 ATP/molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249033
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanisms of coal solubilization by the deuteromycetes Trichoderma atroviride and Fusarium oxysporum (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 57-59 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Three different mechanisms can be envisaged that are used by fungi to solubilize coal: the production of alkaline substances, the extrusion of chelators and, of special interest in the scope of biotechnology, the action of enzymes. Whether these mechanisms are operating separately or in various combinations has not yet been finally assessed. The two deuteromycetes Fusarium oxysporum and Trichoderma atroviride solubilize coal by synergistic effects of various different mechanisms depending on the cell metabolism. F. oxysporum seems to solubilize coal by increasing the pH of the mycelial surroundings and by the action of chelators induced during growth in glutamate-containing media (without involvement of enzymes). T. atroviride, on the other hand, appears to use, in addition to an alkaline pH and a high chelator activity, at least two classes of enzyme activity to attack coal: hydrolytic activity for coal solubilization and ligninolytic activity for degradation of humic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051486
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  • 6
    Electronic Resource
    Electronic Resource
    Evidence for and expression of a laccase gene in three basidiomycetes degrading humic acids (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 66-69 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The majority of lignin-degrading basidiomycetes are able to depolymerize humic acids. In this presentation the relationship and possible similarities between enzymes involved in lignin degradation and humic acid depolymerization were examined on the genetic level. We have cloned fragments of the gene encoding the extracellular ligninolytic enzyme laccase from Clitocybula dusenii, Nematoloma frowardii and a fungal strain designated i63-2, and compared the three sequences with those of several other published laccase genes. The sequenced fragments displayed a high homology both on the DNA (97%–77%) and amino acid (100%–85%) level. Furthermore, the expression of this gene in the above-mentioned fungi was demonstrated by a nested polymerase chain reaction with cDNA as template.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051488
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of simple sequence repeat markers in homozygous lines of apple (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 121 (2002), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Haploids in apple were induced using anther culture and in situ parthenogenesis followed by in vitro culture of immature embryos or cotyledons. In addition to an earlier characterization of the zygosity state using isozymes, the purpose of this work was an analysis of simple sequence repeats (SSRs) to describe the homozygosity more comprehensively. Five previously described SSR primer combinations were applied. Initially, polymerase chain reaction amplification with the primer pairs was performed on the donor genotypes ‘Alkmene’ and ‘Remo’ and on a further four apple cultivars. Only those primer pairs that amplified two different contrasting alleles could be used for investigation of the zygosity state. According to these analyses both the androgenic and parthenogenic regenerated shoots are homozygous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0523.2002.00676.x
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  • 8
    Electronic Resource
    Electronic Resource
    Purification and partial characterization of ubiquitin-activating enzyme from Saccharomyces cerevisiae
    Amsterdam : Elsevier
    FEBS Letters 289 (1991), S. 54-58 
    Details
    ISSN: 0014-5793
    Keywords: Ubiquitin-activating enzyme ; Yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(91)80907-K
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  • 9
    Electronic Resource
    Electronic Resource
    Putative K+ channel inSchizosaccharomyces pombe is regulated by H+, K+ and cAMP at transcriptional level (1996)
    Springer
    Amino acids 10 (1996), S. 359-368 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Potassium channel ; Yeast ; Transcription regulation ; Spasmolytic and hypotensive drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Living cells control their electrical responsiveness by regulating the quality and quantity of channels expressed in the plasma membrane. Regulation of transcription of the voltage-gated ion channels is an important part of the molecular basis of cell energization. However, the factors which control the expression of channels are not well understood. We studied the effect on the transcription of the voltage-gated K+ channel in the yeastSchizosaccharomyces pombe of cations, pH, and therapeutic spasmolytic and hypotensive agents with different mechanisms of action, including accumulation of intracellular cAMP. A highly specific 122 bp domain of the K+ channel between S5 and H5 with a 55% homology with Dros shab and mbk3 was amplified by nested PCR from chromosomal DNAS. pombe. Northern blot revealed a 1.8kb transcript. mRNA dot-blot and RNase-protected analysis revealed factors altering the K+ channel transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805863
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  • 10
    Electronic Resource
    Electronic Resource
    Microdetermination of magnesium and calcium in animal tissue (1963)
    Springer
    Cellular and molecular life sciences 19 (1963), S. 367-368 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Eine Methode zur Bestimmung von 10–40 µg Mg und 5–15 µg Ca in etwa 150 mg Tiergeweben wird beschrieben. Nach Trennung auf Dowex 50-X8 wird Mg mit Komplexon III und Ca mit Na-naphthalohydroxamat bestimmt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02152323
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