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  • Nitrogen fixation  (116)
  • Saccharomyces cerevisiae
  • Springer  (180)
  • American Association for the Advancement of Science
  • American Chemical Society
  • American Institute of Physics (AIP)
  • Blackwell Publishing Ltd
  • 1980-1984  (180)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 22 (1983), S. 205-212 
    ISSN: 1436-6215
    Keywords: Schwermetallwirkung ; Malatdehydrogenase ; Glutamatdehydrogenase ; Glycerinaldehyd-3-phosphatdehydrogenase ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The difference between cadmium, zinc, lead, and mercury in regard of their effects on the activity of the enzymes tested is very slight. Concentrations higher than 10−5 M reduce significantly the activity of the enzymes, and concentrations of approximately 10−3 M inhibit it completely. An increase of the activity cannot be detected. The addition of combinations of cadmium, zinc, and lead results in a summing up of the toxic effects, whereas the interaction between mercury and the other three heavy metals shows a cumulative effect, which is appointed nearly completely by the heavy metal more toxic. The findings suggest that under in-vitro conditions there exists a direct interaction between the heavy metals and the enzymes.
    Notes: Zusammenfassung Die vier Schwermetalle Cadmium, Zink, Blei und Quecksilber unterscheiden sich in ihrer Wirkung auf die Aktivität der untersuchten Enzyme nur sehr wenig. Konzentrationen über 10−5 M vermindern die Enzymaktivität signifikant, und Konzentrationen von etwa 10−3 M unterbinden sie völlig. Eine Steigerung der Enzymaktivität läßt sich nicht feststellen. Die Zugabe von Cadmium-, Zink- und Bleikombinationen führt zu einer Addition der toxischen Effekte, während bei der Interaktion zwischen Quecksilber und den anderen drei Schwermetallen die Gesamtwirkung fast ausschließlich durch das stärker hemmende Schwermetall allein bestimmt wird. Die erhaltenen Ergebnisse lassen vermuten, daß es unter Invitro-Bedingungen zu einer direkten Wechselwirkung zwischen den Schwermetallen und den Enzymen kommt.
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  • 2
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    Cellular and molecular life sciences 40 (1984), S. 1159-1161 
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; 5-trifluoromethyl-6-àzauracil ; yeast cell cultures ; cell division ; inhibition of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cell division, as studied in asynchronous cultures of yeast cells, is sensitive to 5-trifluoromethyl-6-azauracil (F3CAzU). Under defined conditions (10 mmoles l−1 F3CAzU) this compound blocks immediately and completely the process of cell division. Using synchronized cells, the time-point at which division process of yeast cell can be inhibited by F3CAzU has been determined. The inhibitor effect of this compound is completely reversed by thymine, thymidine and uracil.
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  • 3
    ISSN: 1432-0983
    Keywords: Gene cloning ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have carried out experiments aimed at explaining the observed variations in transformation frequencies when Saccharomyces cerevisiae or Saccharomyces carlbergensis are transformed with chimeric plasmids that contain one of 4 possible EcoRI fragments of the yeast 2-μm circle. These plasmids fall into 2 classes when used to transform 2 different yeast his3 auxotrophs, one (strain LL20) harbours indigenous 2-μm circle, and the other (strain YF233) is devoid of this plasmid. Hybrid plasmids containing either the 2.4 mega-dalton (mD) R-form EcoRI fragment (pYF88) or the l.4 mD L-form EcoRI fragment (pYF177) of 2-μm circle transform either of the two hosts at a high frequency (50,000 colonies per Mg in LL20 and 10,000 colonies per μg in YF233). Hybrid plasmids containing the 1.5 mD R-form EcoRI fragment (pYF87) or the 2.5 mD L-form EcoRI fragment (pYF178) of the 2-μm circle transform LL20 at a reduced frequency (6,000–16,000 colonies per μg) and YF233 at extremely low frequencies (1–5 colonies per μg). All plasmids retrieved from strain YF233 that had been transformed with pYF88 or pYF177 were identical to the original transforming plasmid. Of the plasmids retrieved from strain LL20 that had been transformed with pYF87 and pYF178, approximately half had acquired an extra copy of the 2-μm circle. Of the plasmids retrieved from strain LL20 that had been transformed with pYF88 and pYF177, an average of only approximately 13% had acquired an extra copy of 2-μm circle. Taken together, these observations indicate that the transformation of yeast by a plasmid lacking the ability to replicate (pYF87 and pYF1780) occurs by the recombinational acquisition of 1 copy of the host 2-μm circle, which serves to supply the incoming plasmid with missing essential sequences. A comparison of 2-μm circle DNA fragments carried by pYF88 and pYF177 indicates that the region of 2-μm circle required for high frequency transformation is a 1.2 mD segment that is common to the 2.4 mD R-form and 1.4 ml) L-form EcoRI fragments. This region extends from the EcoRI cut site adjacent to the PstI site, through to the end of the inverted repeat. However, the inverted repeat sequence alone is not sufficient to bestow high frequency transformation of yeast.
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  • 4
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    Current genetics 2 (1980), S. 115-120 
    ISSN: 1432-0983
    Keywords: Galactose fermentation ; Saccharomyces cerevisiae ; Regulatory mutant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A novel type of regulatory mutation for galactose metabolism in Saccharomyces cerevisiae is described. The mutation named gal11 was recessive, non-allelic to GAL4, GAL80, GAL2, or GAL3, and unlinked to the gene cluster of GAL1, GAL10, and GAL7. It caused a ‘coordinate’ reduction of galactokinase, galactose-1-P uridylyl transferase, and UDP-glucose 4-epimerase by a factor of more than 5, rendering the mutant cells galactose-nonfermenting. The effect of the mutation was manifested not only in cells grown on galactose but also in cells constitutively synthesizing the galactose-metabolizing enzymes.
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  • 5
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    Current genetics 2 (1980), S. 223-228 
    ISSN: 1432-0983
    Keywords: Transcriptional Units ; GAL Genes ; Saccharomyces cerevisiae ; UV mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The size of the transcriptional unit of the structural genes for three galactose-metabolizing enzymes which form a cluster on chromosome II in Saccharomyces cerevisiae was studied by the ultraviolet light (UV)-mapping technique. Thus the size of the primary transcripts of GAL7 for galactose-1-phosphate uridylyl transferase, GAL10 for uridine diphosphoglucose 4-epimerase, or GAL1 for galactokinase were estimated to be 0.81 x 106, 1.1 x 106, or 1.3 x 106 respectively. In the light of these data together with the known directions of transcription of the genes, we concluded that each of three genes was transcribed from its own promoter.
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  • 6
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    Journal of molecular evolution 21 (1984), S. 19-32 
    ISSN: 1432-1432
    Keywords: Leghemoglobin ; Gene duplication ; Gene linkage ; Concerted evolution ; Nitrogen fixation ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the sequences of soybean leghemoglobin genes as an initial step toward understanding their mode of evolution. Alignment of the sequences of plant globin genes with those of animals reveals that (i) based on the proportion of nucleotide substitutions that have occurred at the first, second, and third codon positions, the time of divergence of plant and animal globin gene families appears to be extremely remote (between 900 million and 1.4 billion years ago, if one assumes constancy of evolutionary rate in both the plant and animal lineages) and (ii) in addition to the normal regulatory sequences on the 5′ end, an approximately 30-base-pair sequence, specific to globin genes, that surrounds the cap site is conserved between the plant and animal globin genes. Comparison of the leghemoglobin sequences with one another shows that (i) the relative amount of sequence divergence in various coding and noncoding regions is roughly similar to that found for animal globin genes and (ii) as in animal globin genes, the positions of insertions and deletions in the intervening sequences often coincide with the locations of direct repeats. Thus, the mode of evolution of the plant globin genes appears to resemble, in many ways, that of their animal counterparts. We contrast the overall intergenic organization of the plant globin genes with that of animal genes, and discuss the possibility of the concerted evolution of the leghemoglobin genes.
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  • 7
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    Applied microbiology and biotechnology 16 (1982), S. 75-80 
    ISSN: 1432-0614
    Keywords: Immobilization of yeast ; Saccharomyces cerevisiae ; Ethanol production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Baker's yeast (Saccharomyces cerevisiae) was immobilized in gels made of prepolymerized, linear, water soluble polyacrylamide, partially substituted with acylhydrazide groups. Gelation was effected by the addition of controlled amounts of dialdehydes (e.g. glyoxal). The immobilized yeasts retained full glycolytic activity. Moreover, the entrapped cells were able to grow inside the chemically corsslinked gel during continuous alcohol production. Glyoxal was found to be the most favourable crosslinking agent for this system. the system employed allowed for the free exchange of substrate and products. The gel surrounding the entrapped cells had no effect on temperature stability profile. On the other hand, substantial enhancement in survival of cells in presence of high ethanol concentrations was recorded for the entrapped yeast. The capability of the immobilized yeast to carry out continuous conversion of glucose to ethanol was demonstrated.
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  • 8
    ISSN: 1432-2048
    Keywords: Alnus ; Ammonium ; Carbon translocation ; Endophyte damage ; Nitrogen fixation ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cloned plants of Alnus incana (L.) Moench were inoculated and grown without combined nitrogen for seven weeks. The effects of ammonium on the function and structure of the root nodules were studied by adding 20 mM NH4Cl (20 mM KCl=control) for four days. Nitrogenase activity decreased to ca. 50% after one day and to less than 10% after two days in ammonium treated plants, but was unaffected in control plants. The results were similar at photon flux densities of 200 and 50 μmol m-2 s-1. At the higher light level the effect was concentration dependent between 2 and 20 mM NH4Cl. The recovery was slow, and more than 11 d were needed for plants treated with 20 mM ammonium to reach initial activity. The distribution of 14C to the root nodules after assimilation of 14CO2 by the plants was not changed by the ammonium treatment. Microscopical studies of root nodules showed high frequencies of endophyte vesicles being visually damaged in nodules from ammonium-treated plants, but not in nodules from control plants. When nitrogenase activity was restored, visually damaged vesicles were again few, whereas young developing vesicles were numerous. The slow recovery, the 14C-translocation pattern, and the structural changes of the endophyte indicate a more complex mechanism of ammonium influence than simply a short-term reduction in supply of carbon compounds to the nodules.
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  • 9
    ISSN: 1432-2048
    Keywords: Ammonia ; Nitrogen fixation ; Nodule ; Senescence (root nodules) ; Ureide ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During early development (up to 18 d after sowing) of nodules of an “effective” cowpea symbiosis (Vigna unguiculata (L.) Walp cv. Vita 3: Rhizobium strain CB756), rapidly increasing nitrogenase (EC 1.7.99.2) activity and leghaemoglobin content were accompanied by rapid increases in activities of glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 2.6.1.53), enzymes of denovo purine synthesis (forming inosine monophosphate) xanthine oxidoreductase (EC 1.2.3.2), urate oxidase (EC 1.7.3.3), phosphoenolpyruvate carboxylase (EC 4.1.1.31) and led to increased export of ureides (allantoin and allantoic acid) to the shoot of the host plant in the xylem. Culturing plants with the nodulated root systems maintained in the absence of N2 (in 80 Ar: 20 O2, v/v) had little effect on the rates of induction and increase in nitrogenase activity and leghaemoglobin content but, in the absence of N2 fixation and consequent ammonia production by bacteroids, there was no stimulation of activity of enzymes of ammonia assimilation or of the synthesis of purines or ureides. Addition of NO 3 - (0.1–0.2 mM) relieved host-plant nitrogen deficiency caused by the Ar: O2 treatment but failed to increase levels of enzymes of N metabolism in either the bacteroid or the plant-cell fractions of the nodule. Premature senescence in Ar: O2-grown nodules occurred at 18–20 d after sowing, and resulted in reduced levels of nitrogenase activity and leghaemoglobin but increased the activity of hydroxybutyrate oxidoreductase (EC 1.1.1.30).
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  • 10
    ISSN: 1432-2048
    Keywords: Ammonium assimilation ; Glycine ; Nitrogen fixation ; Proplastid ; Purine synthesis ; Root nodule ; Ureide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Subcellular organelle fractionation of nitrogen-fixing nodules of soybean (Glycine max (L.) Merr.) indicates that a number of enzymes involved in the assimilation of ammonia into amino acids and purines are located in the proplastids. These include asparagine synthetase (EC 6.3.1.1), phosphoribosyl amidotransferase (EC 2.4.2.14), phosphoglycerate dehydrogenase (EC 1.1.1.95), serine hydroxymethylase (EC 2.1.2.1), and methylene-tetrahydrofolate dehydrogenase (EC 1.5.1.5). Of the two isoenzymes of asparate aminotransferase (EC 2.6.1.1) in the nodule, only one was located in the proplastid fraction. Both glutamate synthase (EC 1.4.1.14) and triosephosphate isomerase (EC 5.3.1.1) were associated at least in part with the proplastids. Glutamine synthetase (EC 6.3.1.2) and xanthine dehydrogenase (EC 1.2.1.37) were found in significant quantities only in the soluble fraction. Phosphoribosylpyrophosphate synthetase (EC 2.7.6.1) was found mostly in the soluble fraction, although small amounts of it were detected in other organelle fractions. These results together with recent organelle fractionation and electron microscopic studies form the basis for a model of the subcellular distribution of ammonium assimilation, amide synthesis and uredie biogenesis in the nodule.
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  • 11
    ISSN: 1432-2048
    Keywords: Allantoin ; Amino acids ; Bleeding sap ; Nitrogen fixation ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark 14CO2 assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with 14CO2, bleeding sap from plants root fed 14CO2 contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.
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  • 12
    ISSN: 1432-2048
    Keywords: Glyoxylate ; Isonicotinic acid hydracide ; Medicago ; Nitrogen fixation ; Photorespiration ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fixation (measured as acetylene reduction) by whole nodulated alfalfa plants was stimulated when the plants were treated with isonicotinic acid hydracide (INH) and glyoxylate, both inhibitors of the glycolate pathway of carbohydrate metabolism, at concentrations of 300 and 100 mM, respectively. Reducing energetic loses caused by photorespiration results in an increase in the symbiotic nitrogen fixation.
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  • 13
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    Planta 152 (1981), S. 544-552 
    ISSN: 1432-2048
    Keywords: Ammonium assimilation ; Lichens ; Nitrogen fixation ; Peltigera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Nostoc in the cephalodia of the lichen Peltigera aphthosa Willd. fixed 15N2 and the bulk of the nitrogen fixed was continuously transferred from it to its eukaryotic partners (a fungus and a green alga, Coccomyxa sp.). Kinetic studies carried out over the first 30 min, after exposure of isolated cephalodia to 15N2, showed that highest initial 15N2-labelling was into NH 4 + . After 12 min little further increase in the NH 4 + label occurred while that in the amide group of glutamine and in glutamate continued to increase. The 15N-labelling of the amino group of glutamine and of aspartate increased more slowly, followed by an increase in the labelling of alanine. When total incorporation of 15N-label was calculated, the overall pattern was found to be rather similar except that, throughout the experiment, the total 15N incorporated into glutamate was about six times greater than that into the amide group of glutamine. Pulse chase experiments, in which 14N2 was added to cephalodia previously exposed to 15N2, showed that the NH 4 + pool rapidly became depleted of 15N-label, followed by decreases in the labelling of glutamate, the amide group of glutamine and aspartate. The 15N-labelling of alanine, however, continued to increase for a period. When isolated cephalodia were treated with L-methionine-SR-sulphoximine, an inhibitor of glutamine synthetase (EC 6.3.1.2), and azaserine, an inhibitor of glutamate synthase (EC 2.6.1.53), there was no detectable labelling in glutamine although the 15N-labelling of glutamate increased unimpaired. On treating the cephalodia with amino-oxyacetate, an inhibitor of aminotransferase activity, the alanine pool decreased. Evidence was obtained that glutamine synthetase and glutamate synthase were located in the Nostoc, and that glutamate dehydrogenase (EC 1.4.1.4) and various amino-transferases were located in the cephalodial fungus. Possible implications of these findings are discussed.
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  • 14
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Multiple mutants of DNA repair ; Sensitivity to nitrogen mustard and to radiation ; Thermoconditional DNA repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three haploid yeast mutants (snm) sensitive or thermoconditionally sensitive to the DNA cross-linking agent nitrogen mustard (HN2) were crossed with four rad strains representing mutations in the three pathways of DNA dark repair. The resulting haploid double and triple mutant strains were tested for their sensitivity to UV, HN2 and HN1. From the observed epistatic or synergistic interactions of the combinations of mutant alleles we could derive the relation of the SNM1 and SNM2 genes to the postulated repair pathways. Alleles snm1-1 and snml-2 ts were found epistatic to genes of the rad3 group, whereas snm2-1 ts was epistatic to rad6. The snm1 and snm2 mutant alleles interacted synergistically. From these data it is concluded that the SNM1 gene product plays a cross-link specific role in excision repair while the SNM2 gene product may be involved in a system of error-prone repair.
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  • 15
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    Current genetics 7 (1983), S. 165-166 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Cephalosporium acremonium ; Mitochondrial hybrid vector ; Nuclear association
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hybrid vector pCP2, consisting of the bacterial plasmid pBR325, the nuclear gene Leu-2 of Saccharomyces cerevisiae and a fragment of mitochondrial DNA from Cephalosporium acremonium, was found to associate with the nucleus in a transformed strain of Saccharomyces cerevisiae. This was inducted by (1) efficient expression of the Leu-2 gene as evidenced by a short generation time on selective medium; (2) independence of Leu-2 gene expression from mitochondrial protein synthesis, since pCP2 was shown to replicate and to be expressed in petite mutants; (3) association of pCP2 with isolated DNA from nuclei as proved by transformation experiments with E. coli.
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  • 16
    ISSN: 1432-0983
    Keywords: Catalase ; Saccharomyces cerevisiae ; Heme ; Posttranscriptional control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Compared to wild type cells, strains bearing the pleiotropic regulatory mutations cgr4 or cas1 synthesize apocatalase T at a high rate when grown on high glucose. Like heme-deficient ole3 single mutants, ole3 cgr4 and ole3 cas1 double mutants accumulate no catalase T protein in vivo. This defect introduced by the ole3 mutation is cured by the addition of ALA. By use of the inhibitor actinomycin D we confirm previous findings that ole3 mutants lack catalase T mRNA and show that (i) the ole3 cgr4 and ole3 cas1 double mutants do accumulate catalase T mRNA or mRNA precursor, and (ii) the processing or translation of this RNA or the accumulation of apocatalase T depends on the presence of home.
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  • 17
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; G1 cdc mutants ; tα-factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutants in four G1 cdc strains of Saccharomyces cerevisiae were isolated which failed to show division arrest in the presence of α-factor. The cell cycle properties, terminal arrest morphology and mating competence of these mutants at the restrictive temperature were examined. The G1 specific arrest of the cdc 36 and cdc39 mutants is dependent upon the availability of an intact mating factor response system in Mat a cells. Cdc28 and cdc37 mutants exert their cell cycle blocks independently of the mating factor pathway. It is likely that the nature of the primary growth defect in cdc36 and cdc39 mutants is such that the α-factor pathway is activated in the absence of the pheromone at the restrictive temperature and that G1 arrest is a secondary consequence of a non-cycle specific event in such mutants.
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  • 18
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    Current genetics 7 (1983), S. 235-237 
    ISSN: 1432-0983
    Keywords: DNA replication ; Shuttle vectors ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitotic segregation of three 2 μm-pBR322 chimaeric plasmids (YEp6, YEp21, and YEp24) was studied in yeast. Each displayed a characteristic rate of loss: YEp6 was lost at approximately twice the rate of YEp21 and YEp24. The loss rates were not significantly increased when two chimaeric plasmids were coresident, nor was the endogenous 2 μm plasmid itself displaced. Therefore these plasmids appear to be compatible in yeast.
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  • 19
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    Current genetics 8 (1984), S. 559-566 
    ISSN: 1432-0983
    Keywords: DNA repair ; Saccharomyces cerevisiae ; Cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three overlapping plasmids were isolated from a YEp24 library, which restore Rad+ functions to rad6-1 and rad6-3 mutants. Different subclones were made and shown to integrate by homologous recombination at the RAD6 site on chromosome VII, thus verifying the cloned DNA segments to be the RAD6 gene and not a suppressor. The gene resides in a 1.15 kb fragment, which restores Rad+ levels of resistance to U.V., MMS and γ-rays to both rad6-1 and rad6-3 strains. It also restores sporulation ability to rad6-1 diploids. Integrative deletion of the RAD6 gene was shown not to be completely lethal to the yeast. Our results suggest that the RAD6 gene has some cell cycle-specific function(s), probably during late S phase.
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  • 20
    ISSN: 1432-0983
    Keywords: α-Pheromone-inactivating glycoproteins ; bar1-1 ; Barrier proteins ; Purification ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two kinds of a-mating-type-specific proteins inactivating α pheromone (α factor) were purified from heat shock extract of MATa cells. Their molecular weights were estimated to be 400,000 and 200,000 by gel filtration. Both proteins were detected in MATa SST1 cells but not in MATα SST1, MATa sst1-1 and MATa/MATα SST1/SST1 cells. In addition, the proteins were detected in matα2-1 SST1 cells but not in matα1-2 SST1 cells. From these results, it is concluded that these proteins are synthesized under the control of the SST1 gene and responsible for the Barrier action of MATa cells. The relationship of these proteins to the secreted Barrier protein having a higher molecular weight is discussed.
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  • 21
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    Current genetics 4 (1981), S. 85-90 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Nuclear isolation ; Percoll ; in vitro Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A procedure has been developed for the rapid isolation of yeast nuclei in high yield using Percoll gradients. The nuclei are substantially free of cytoplasmic contamination as measured by alcohol dehydrogenase activities, have the typical chromatin digestion pattern when digested with nucleases, are useful for isolation of nuclear proteins and for in vitro transcription experiments.
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  • 22
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; DEL1 ; rad ; ste7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In DEL1 strains of the yeast, Saccharomyces cerevisiae, the iso-1-cytochrome c (CYC1) region is flanked on either side by Tyl elements in direct orientation which promote cyc1 deletions of the bracketed DNA in the haploid cell. In this study, we asked which genes might control this event by testing the possibility that the DEL1 mutation mechanism requires an enzyme (or enzymes) that is also utilized in the repair of damaged DNA. To this end, we independently coupled eight repair mutations, rad3–2, rad4–4, rad6–1, rad6–3, rad9–1, rev3–1, rad50–1, and rad51-1, toDEL1 and asked whether DEL1 was still functional. We found that none of these rad mutations significantly affects the mutation frequency of 10−6-10−5 established in DEL1 strains for the CYC1 locus. Furthermore, we determined that ste7, a temperature-sensitive sterile allele known to alter gene regulation in Ty-mediated mutations, is not required for DEL1 function. Finally, DEL1 is not temperature-sensitive at 23° or 37 °C.
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  • 23
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    Current genetics 7 (1983), S. 369-377 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Isoenzymes ; Induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tetrad analysis indicates that α-isopropylmalate synthase activity of yeast is determined by two separate genes, designated LEU4 and LEU5. LEU4 is identified as a structural gene. LEU5 either encodes another α-isopropylmalate synthase activity by itself or provides some function needed for the expression of a second structural gene. The properties of mutants affecting the biosynthesis of leucine and its regulation suggest that the expression of LEU1 and LEU2 (structural genes encoding isopropylmalate isomerase and β-isopropylmalate dehydrogenase, respectively) is controlled by a complex of a-isopropylmalate and a regulatory element (the LEU3 gene product). Similarities and differences between yeast and Neurospora crassa with respect to leucine biosynthesis are discussed.
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  • 24
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; TRP3 gene ; Deletion analysis ; Enzyme function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two sets of deletions, entering the TRP3 gene of Saccharomyces cerevisiae from the 3′- and the 5′-end were constructed. Complementation analysis with chromosomal trp3A, trp3B and trp3C mutations was done by introducing the 3′- and 5′-truncated gene on a multicopy 2 μm-vector. The N-terminal glutamine amido transferase function is encoded by a DNA fragment of 600–700 bp, and the C-terminal indole-3-glycerol-phosphate synthase function by a DNA fragment of about 900 bp, whereas both functions together are encoded by a contiguous DNA fragment of about 1,500 bp. The bi functional TRP3-peptide thus could be dissected into two catalytically independent peptides in vivo. For the indole-3-glycerol-phosphate synthase activity, independent catalytic activity was also demonstrated in vitro: deletions entering the TRP3 gene from the 5′-end, and lacking large parts of the sequence coding for the glutamine amidotransferase function, still are able to ex press a peptide exhibiting functional indole-3-glycerol phosphate synthase activity in vitro. Deletion plasmids pME505·De1C102·2μm and DelC10·2μm exhibited shorter TRP3 transcripts according to the deleted DNA-fragments (150 and 426 by respectively) but yielded peptides of invariable Mr of 35,000 d. Transcription and translation of these peptides, which probably represent the independently folding indole-3-glycerol-phosphate synthase core are discussed.
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  • 25
    ISSN: 1432-0983
    Keywords: Cephalosporium acremonium ; Mitochondrial DNA ; Autonomous replication sequence ; Saccharomyces cerevisiae
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    Topics: Biology
    Notes: Summary A fragment of DNA which functions as an autonomous replication sequence in yeast was cloned from Cephalosporium acremonium. Mitochondrial DNA (mtDNA) was isolated from an industrial strain of C. acremonium (08G-250-21) highly developed for the production of the antibiotic, cephalosporin C. Size, 27 kb, and restriction pattern indicated this DNA was identical to mtDNA previously isolated (Minuth et al. 1982) from an ancestral strain (ATTC 14553) which produces very low amounts of cephalosporin C. A 1.9 kb Pst1 fragment of the Cephalosporium mtDNA was inserted into a Pst1 site of the yeast integrative plasmid, Ylp5, to produce a 7.5 kb plasmid, designated pPS1. The structure of pPS1 was verified by restriction analysis and hybridization. PS1 transformed Saccharomyces cerevisiae (DBY-746) to uracil prototrophy at a frequency of 272 transformants/μg DNA. Transformation frequencies of 715 transformants/μg DNA and zero were obtained for the replicative plasmid, YRp7, and the integrative plasmid YIp5, respectively. Southern hybridization and transformation of E. coli by DNA from yeast transformed by pPS1 verified that pPS1 replicates autonomously in yeast. The uracil-independent pPS1-yeast transformants were mitotically unstable. The average retention of pPS1 after three days growth in selective and non-selective medium was 4.5% and 0.4%, respectively, compared to retentions of 4.6% and 0.5% for YRp7. The properties of pPS1 were compared to those of a related plasmid, pCP2. pCP2 was constructed (Tudzynski et al. 1982) by inserting the C. acremonium 1.9 kb Pst1 fragment into the yeast integrative plasmid, pDAM1.
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  • 26
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    Environmental management 7 (1983), S. 177-187 
    ISSN: 1432-1009
    Keywords: Nitrogen ; Model ; Agriculture ; Mass balance ; Ground-water ; Denitrification ; Immobilization ; Dry deposition ; Nitrogen fixation ; Nitrate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A detailed nitrogen budget was devised for agricultural activities in the Florida peninsula, based on routine data published by state agricultural agencies. The model demonstrates that important unmonitored fluxes of nitrogen can often be calculated by mass balance on individual model compartments, and that the reasonability of poorly quantified fluxes can be assessed. The results of such models can be very useful in designing and assessing the results of field experiments and in prioritizing environmental monitoring programs.
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  • 27
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Yeast vectors ; Cosmids ; nif genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two vectors, termed pG63.11 (7.6 Kb) and pHCG3 (9.6 Kb), suitable for yeast transformation have been constructed. The pHCG3 vector has cosmid properties. Both vectors contain a single 3.3 Kb EcoRI-HindIII fragment of yeast origin which carries the yeast URA3 gene (1.1 Kb) and the origin of replication of the 2 µm plasmid (2.2 Kb). They confer ampicillin resistance and they contain 5 unique EcoRI,HpaI,HindIII,BamHI and SalI restriction sites. Cosmid pHCG3 was used to clone the nitrogen fixation (nif) gene cluster of Klebsiella pneumoniae carried by twoHindIII fragments of 17 and 26 Kb, respectively. The resulting cosmid, termed pGPC875 (53 Kb) which conferred a Nif+ phenotype to Escherichia coli, was introduced in yeast by transformation. No acetylene reduction activity was detectable in the transformants. However it was shown that the entire information for nitrogen fixation can be replicated and maintained intact in yeast for more than 50 generations of growth.
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  • 28
    ISSN: 1432-0983
    Keywords: Suppressors-tRNA ; Saccharomyces cerevisiae ; Nucleotide modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have examined the tRNAs of two related strains of Saccharomyces cerevisiae, ψ + and ψ −, which differ with respect to an extrachromosomal genetic element that modulates the expression of genotypic and phenotypic suppression. Both the pattern of tRNAs synthesized and the level of nucleotide modification of several selected tRNA species were found to be the same in the ψ + and ψ − strains.
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  • 29
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    Current genetics 6 (1982), S. 163-165 
    ISSN: 1432-0983
    Keywords: Hybridization ; Polyethylene glycol ; Nuclear transfer ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Viable hybrids of Saccharomyces cerevisiae were obtained by transfer of isolated diploid nuclei into haploid protoplasts using a polyethylene glycol (PEG) fusion procedure.
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  • 30
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    Current genetics 7 (1983), S. 393-397 
    ISSN: 1432-0983
    Keywords: Trehalose ; Glycogen ; Sporulation ; Germination ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutants with specific lesions were used to differentiate between the functions of glycogen and trehalose in S. cerevisiae. Diploids which harbor the glc1/glc1 mutation depend upon the phosphorylated, less active form of glycogen synthase and show a more active, phosphorylated form, of the enzyme trehalase. These conditions are due to a lesion in the regulating subunit of the cAMP-dependent protein kinase. Such cells are unable to sporulate. Diploids which contain the sst1/sst1 mutation have normal glycogen metabolism but their trehalose-6-phosphate synthase is not active. Such strains sporulate but germination is poor and only one-spore tetrads are formed. These results confirm that glycogen is needed to trigger sporulation while trehalose plays a role in the germination process. Different systems, I and II, of trehalose accumulation were proposed. System I would require the UDPG-linked trehalose synthase, whereas system II would constitute an alternative pathway, specifically induced or activated by the expression of a MAL gene. The presence of system II in its constitutive form in the constructed diploids would favour trehalose synthesis during growth on glucose, however, it did not overcome the glycogen deficiency during sporulation nor the lack of trehalose for germination. It seems that only system I, namely trehalose 6-P-synthase, plays a role in the germination process.
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  • 31
    ISSN: 1432-0983
    Keywords: Oversecretion mutants ; Protease defect ; Wall glucan defect ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two chromosomal mutations in yeast that result in oversecretion of the K1 killer toxin protein were examined. A recessive mutation in gene ski5 appears to lead to toxin oversecretion through a defect in a cell surface, PMSF-inhibited protease. A wild type killer strain degraded toxin following synthesis, and degradation could be partially prevented by addition of PMSF to the growth medium. The ski5 mutation caused an approximate ten fold oversecretion of toxin, similar to that seen in a PMSF-treated wild type culture, and no increased oversecretion in the presence of PMSF. The ski5 mutation caused oversecretion of other low molecular weight secreted proteins and appeared to oversecrete the α-factor pheromone, as judged by activity tests. The ski5 mutation was complemented by mutations in ski genes 1–4, and the mutant was not supersensitive to mating pheromones or K2 killer toxin. We also examined killer strains with a mutation in the nuclear gene krel which results in a defective (1→6)-β-D-glucan cell wall receptor for killer toxin. Such strains oversecrete toxin into the growth medium, but also, unexpectedly, oversecrete most other secreted proteins. The defect in (1→6)-β-D-glucan in these mutants appears to perturb the partitioning of secreted proteins between the cell wall and the medium.
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  • 32
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; 5-aminolevulinate synthase ; Cloned gene
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    Notes: Summary We have cloned the structural gene HEM1 for 5-aminolevulinate (ALA) synthase from Saccharomyces cerevisiae by transformation and complementation of a yeast hem1–5 mutant which was previously shown to lack ALA synthase activity (Urban-Grimal and Labbe Bois 1981) and had no immunodetectable ALA synthase protein when tested with yeast ALA synthase antiserum. The gene was selected from a recombinant cosmid pool which contained wild-type yeast genomic DNA fragments of an average size of 40 kb. The cloned gene was identified by the restauration.of growth on a non fermentable carbon source without addition of exogenous ALA. Sub cloning of partial Sau3A digests and functional analysis by transformation allowed us to isolate three independent plasmids, each carrying a 6 kb yeast DNA fragment inserted in either orientation into the single BamHI site of the vector pHCG3 and able to complement hem1–5 mutation. Analysis of the three plasmids by restriction endonucleases showed that HEM1 is contained within a 2.9 kb fragment. The three corresponding yeast trans formants present a 1, 2.5 and 16 fold increase in ALA synthase activity as compared to the wild-type strain. The gene product immunodetected in the transformant yeast cells has identical size as the wild-type yeast ALA synthase and its amount correlates well with the increase in ALA synthase activity.
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  • 33
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    Current genetics 6 (1982), S. 159-162 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Transformation ; Gene subcloning
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    Topics: Biology
    Notes: Summary We have developped a procedure to delimit the boundaries of a cloned gene carried on a DNA fragment as large as 4 to 5 kilobases. The method consists in the following. Two series of limit digest products generated with a tetranucleotide recognition sequence endonuclease and originating from either of the two ends of this DNA segment are tested for their complementing capacity by yeast transformation. The gene is then delimited by the overlap of the two shortest complementing fragments.
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  • 34
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    Current genetics 9 (1984), S. 107-111 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; 2 μm minichromosomes ; Metrizamide gradients
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    Topics: Biology
    Notes: Summary Two micrometer minichromosomes from Saccharomyces cerevisiae were isolated without detergent using metrizamide gradients. 2 μm minichromosomes showed a lower density in metrizamide gradients relative to genomic chromatin. Our results suggest a lower ratio of proteins to DNA in 2-μm minichromosomes as compared with genomic chromatin. The procedure described herein yields minichromosomes free of cellular chromatin and ribosomal protein contamination. This method may be useful for the isolation and characterization of other yeast minichromosomes.
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  • 35
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    Current genetics 7 (1983), S. 427-431 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; DNA ; Alkaline elution
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    Topics: Biology
    Notes: Summary The method of analysis of DNA in mammalian cells by alkaline elution from filters (Kohn et al. 1974) was adapted for studies on yeast DNA. By this technique spheroplasts obtained from yeast cells are lysed on filters and single-stranded DNA fragments selectively eluted by alkaline solutions. The procedure was applied to monitor the occurrence of replication intermediates and production of DNA single-strand breakage by MMS, and its repair in growth medium.
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  • 36
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    Current genetics 8 (1984), S. 81-84 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mitochondrial genes ; Vegetative segregation ; Uniparental inheritance
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    Topics: Biology
    Notes: Summary Zygotes of Saccharomyces cerevisiae that are heteroplasmic for mitochondrial alleles produce diploid progeny that are homoplasmic for one allele or the other, judged by the criterion that upon further subcloning they produce daughter cells of only one phenotype or the other. Here we show that when such cells are subjected to strong selection for the missing allele, it cannot be detected, so that it is probably not present in even a single copy.
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  • 37
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    Current genetics 4 (1981), S. 135-143 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mitochondria ; Gene cloning ; Transfer RNA
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    Topics: Biology
    Notes: Summary We have studied the organization and expression of a group of tRNA genes located on a 2,700 base pair portion of the yeast mitochondrial genome between the genetic markers cap (chloramphenicol resistance) and oxil (cytochrome oxidase subunit II). This region is spanned by mitochondrial DNA inserts of two recombinant plasmids, pYm162 and pYm267, which have been extensively mapped and sequenced. This tRNA group is composed of six tRNA genes, coding for tRNA AAR Lys , tRNA AGR Arg , tRNA GGN Gly , tRNA GAY Asp , tRNA AGY Ser , and tRNA CGN Arg . We report the sequence for the majority of the 2,700 base pair region including the genes for all six tRNAs. All six genes are oriented in the same direction and are, therefore, transcribed from the same DNA strand. Further, a comparison of the organization of this region with the analogous region of a related wild type strain shows that the tRNA gene order in the two strains is the same. Five of the six tRNA genes have corresponding transcripts in wild type RNA. Although a potential structural gene for tRNA CGN Arg is present, we do not detect a tRNA CGN Arg gene transcript.
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  • 38
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; TRP2 gene ; TRP3 gene ; Cloning in yeast
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    Notes: Summary This paper describes the isolation of the TRP2 and the TRP3 genes of Saccharomyces cerevisiae. Two pools of plasmids consisting of BamHI and Sa1GI yeast DNA inserts into the bifunctional yeast — Escherichia coli vector pLC544 (Kingsman et al. 1979) were constructed in E. coli and used for the isolation of the two genes by selection for functional complementation of trp2 and trp3 mutations, respectively, in yeast. The TRP2 gene was isolated on a 6.2 kb BamHl and a 5.8 kb Sa1GI yeast DNA fragment which shared an identical 4.5 kb BamHI-SaIGI fragment. The TRP3 gene was located on a 5.2 kb BamHl fragment. By physical, genetic and physiological experiments it could be shown that the cloned yeast DNA fragments contained the whole structural sequences as well as the regulatory regions of the TRP2 and the TRP3 genes.
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  • 39
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    Current genetics 7 (1983), S. 433-438 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Yeast transformation ; Yeast autonomously replicating sequences ; Ribosomal RNA genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously demonstrated that the loss of Rcp-CEN3, a centromeric plasmid containing yeast rDNA autonomously replicating sequences (ARS) is as high as around 50% per generation for most yeast strains. In this study we have attempted to elucidate mechanisms underlying the high mitotic instability of Rcp-CEN3. For this purpose a tandem duplication of a rDNA ARS was constructed in Rcp-CEN3. The new plasmid having two ARSs possesses a markedly higher mitotic stability as compared to a monoARS Rcp-CEN3. The mitotic stability of this centromere-containing plasmid which has two replicators corresponds to the calculated value for the mitotic stability of two monoARS plasmids Rcp-CEN3 in given cells. Genetic analysis has demonstrated that both plasmids having one or two ARSs are maintained in the single copy state. These results demonstrate that the mitotic instability of centromeric plasmid Rcp-CEN3 carrying a rDNA ARS is associated with the absence of stringent control of replication from the rDNA ARS. A possible mechanism of replication of the chromosomal rDNA repeats in yeast is discussed in the light of this data.
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  • 40
    ISSN: 1432-0983
    Keywords: Iso-1-cytochrome c ; Saccharomyces cerevisiae ; Heme ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A Saccharomyces cerevisiae mutant (hem1 cycl-1) was transformed with plasmids bearing a chromosomal centromer (CEN3) and a 2 μm DNA replication origin. In one of the plasmids a functional CYC1 gene was present, in a second plasmid an XhoI fragment located between bases -245 and -678 upstream from the translation initiation codon had been deleted, in a third plasmid this region had been inverted. Results of hybridization experiments carried out with mRNA isolated from heme-deficient and heme-containing transformants indicated that heme controls transcription of the CYC1 gene and that DNA sequences located within the upstream XhoI fragment are involved in activation of the gene by heme.
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  • 41
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; TRP3 gene ; Sequence analysis ; Enzyme function
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    Notes: Summary The structure and function of the TRP3 gene of Saccharomyces cerevisiae were analyzed. Subcloning of an original 4.8 kb BamHI DNA fragment, carrying the yeast TRP3 gene, allowed for a localization of the gene on a 2.5 kb ClaI/BamHI fragment. Transcription was found to proceed from the ClaI site towards the BamHI site. Three major transcription start sites were determined at positions −92, −87, and −81 by S1-mapping. The synthesis of the TRP3 gene is regulated by the general control, and was found to take place- at the transcriptional level. The sequence of the 5′-noncoding region up to position −400 and part of the coding region to position 840 were determined. The 5′-noncoding region contains sequences common to most amino acid biosynthetic genes known so far, namely a presumptive ribosome binding site, “Goldberg-Hogness boxes”, and a consensus sequence, possibly involved in the general control. For the coding region a single open reading frame was found. The deduced amino acid sequence was aligned with homologous amino acid sequences of Neurospora crassa, Pseudomonas putida and Escherichia coli. The exceptionally high homology (40–60%) between these sequences led us to postulate that the TRP3 gene product is of the structure NH2-glutamine amidotransferase-indole-3-glycerol-phosphate synthase-COOH.
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  • 42
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Cloning ; Suppressor
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    Notes: Summary A plasmid, pYsup1-1, containing a DNA fragment able to suppress the recessive mutant phenotype of the suppressor locus sup1 (allele sup1-ts36) of Saccharomyces cerevisiae was isolated from a bank of yeast chromosomal DNA cloned in cosmid p3030. The complementing gene was localized on a 2.6 kb DNA fragment by further subcloning. Evidence is presented that the cloned DNA segment codes for the sup1 structural gene (chromosome IIR).
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  • 43
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    Current genetics 8 (1984), S. 575-580 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Candida utilis ; Protoplast fusion
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    Notes: Summary Auxotrophic mutants of Saccharomyces cerevisiae and Candida utilis were hybridized through protoplast fusion. Spontaneous, UV- and FPA-induced mitotic segregation indicated that after cell fusion, exclusion of the S. cerevisiae nucleus or nuclear fusion followed by preferential loss of S. cerevisiae chromosomes can take place. Some of the hybrids were stable. One of them, expressed mating and sporulation functions of the S. cerevisiae parent. Thus, markers from both parents could be recovered as mitotic and meiotic segregants.
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  • 44
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    Archives of microbiology 128 (1980), S. 157-161 
    ISSN: 1432-072X
    Keywords: Lactobacillus brevis ; Streptococcus lactis ; Saccharomyces cerevisiae ; Concanavalin A ; Symbiosis ; Tibi
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    Notes: Abstract Tibi grains consist of a unique and very stable symbiotic association of Lactobacillus brevis, Streptococcus lactis and Saccharomyces cerevisiae embedded in a dextran matrix. The structural organization of the grain was examined by light, scanning and transmission electron microscopy. The grain was constituted of an outer compact layer and an inner spongy structure. The outer layer was more densely populated by the microorganisms than the inner layer but dextran, stained on frozen thin sections with fluorescein-conjugated concanavalin A, was more abundant in the inner layer.
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  • 45
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Regulation ; Guanosine 5′-diphosphate 3′-diphosphate (ppGpp)
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    Notes: Abstract Addition of ammonium to N2 fixing cultures of Azotobacter vinelandii, Klebsiella pneumoniae and Clostridium pasteurianum rapidly reduced the intracellular levels of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) by 70–90%. This change might reflect a regulatory role of ppGpp in nitrogen metabolism.
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  • 46
    ISSN: 1432-072X
    Keywords: a Pheromone ; α Pheromone ; Hansenula wingei ; Inducible mutant ; Saccharomyces cerevisiae ; Saccharomyces kluyveri ; Sexual agglutinability ; Shmoo ; Synthetic analogues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three analogues of the peptidyl pheromone, α pheromone of Saccharomyces kluyveri, synthesized based on the amino acid sequence proposed by Sato et al. (Agric Biol Chem 45:1531–1533, 1981) were tested for both shmoo-inducing and agglutinability-inducing actions. Purified natural α pheromone of the yeast showed the highest activity among the peptides tested. When methionine in the peptides was oxidized, the activity decreased significatly. α Pheromone of S. kluyveri induced sexual agglutinability in a cells of Saccharomyces cerevisiae, and shmoo in a cells of S. cerevisiae and S. kluyveri. a Pheromone of S. kluyveri had no agglutinability-inducing action on α cells of S. cerevisiae. a Cells of S. kluyveri inactivated only α pheromone of the same species, but a cells of S. cerevisiae inactivated α pheromones of both S. cerevisiae and S. kluyveri.
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  • 47
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    Archives of microbiology 136 (1983), S. 20-25 
    ISSN: 1432-072X
    Keywords: Hydrogen production ; Nitrogen fixation ; Hydrogen recycling ; Hydrogenase
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    Notes: Abstract Mutants of Rhodopseudomonas capsulata lacking uptake hydrogenase activity have been isolated among those unable to grow photoautotrophically. Studies with these mutants showed increases in nitrogenase mediated H2 production from all substrates tested. In addition, photosynthetic synthetic growth on N2 with malate as carbon source was not affeced by the block in H2 uptake even under low light. Under these growth conditions hydrogen was observed to accumulate in mutant but not in wild-type cultures. This finding suggested that H2 was evolved by nitrogenase during N2 fixation by this photosynthetic bacterium and was efficiently recycled in the wild type.
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  • 48
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Borrelidin ; Aspartokinase ; Feedback regulation ; Threonine pool ; Homoserine pool ; S-Adenosylmethionine
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Borrelidin is a specific inhibitor of the threonyl-tRNA-synthethase. A class of dominant borrelidin resistant mutants (BOR1) of Saccharomyces cerevisiae was biochemically characterized. The mutants possess an altered aspartokinase which is insensitive to threonine inhibition. The threonine and homoserine pools in these mutants are 22 times larger than in the wild type. By feeding aspartate under a variety of conditions the homoserine pool is increased even 57 times whilst the threonine pool is reduced.
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  • 49
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    Archives of microbiology 135 (1983), S. 287-292 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Respiration ; Nitrogen fixation ; Heterocysts ; K m for O2 ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of acetylene reduction by Anabaena variabilis and the concentration of dissolved oxygen in the suspension were made using a specially designed vessel which allowed measurements under steady-state conditions. The rate of acetylene reduction in the dark increased with increasing oxygen concentrations until a maximum value was reached at 300 μM O2 (corresponding to 30% O2 in the gas phase at 35°C). This presumably results from a requirement for energy provided by respiration. Measurements of the dependence of respiration rate on dissolved oxygen concentration were made under comparable conditions using an open system to allow conditions close to steady-state to be obtained. The respiration rate of diazotrophically grown Anabaena variabilis had a dependence on oxygen concentration corresponding to the sum of two activities. These had K m values of 1.0 μM and 69 μM and values of V max of similar magnitude. Only the high affinity activity was observed in nitrate-grown cyanobacteria lacking heterocysts, and this presumably represent activity in the vegetative cells. The oxygen concentration dependence of the low affinity activity resembled that for the stimulation of acetylene reduction. We interpret this as the result of oxygen uptake by the heterocysts. The results are consistent with the idea that in intact filaments of cyanobacteria O2 enters heterocysts much more slowly than it enters the vegetative cells.
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  • 50
    ISSN: 1432-072X
    Keywords: Agglutination substance ; α Pheromone ; Cell cycle ; Ethyl N-phenylcarbamate ; Mating reaction ; Microtubules ; Saccharomyces cerevisiae
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    Notes: Abstract Effects of ethyl N-phenylcarbamate (EPC) on the mating reaction of Saccharomyces cerevisiae were studied, with special attention on the effect on the α pheromone action. EPC inhibited zygote formation at a concentration which promoted induction of sexual agglutinability. EPC enhanced agglutinability induction by α pheromone, but inhibited α-pheromone-induced formation of large pearshaped cells in a mating type. The enhancement of agglutinability induction was accompanied with increased production of a agglutination substance and inhibition of α pheromone inactivation. EPC arrested the cell cycle of a cells probably in the step controlled by CDC19, CDC35, cAMP etc., just before the step controlled by CDC28, α pheromone etc.
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  • 51
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Glucan synthetase ; EDTA ; Magnesium ; Sucrose ; Fluoride
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    Notes: Abstract Yeast β(1–3) glucan synthetase is stimulated and stabilized by EDTA. Sucrose protects the enzyme from selfinactivaton. Preincubation of cell free extracts at low sucrose concentrations indicates a slow transition of the enzyme towards dissociation. Transition kinetics at 30° C and 0° C in the presence and in the absence of sucrose are interpreted assuming that a subunit is thermolabile in the free state and that sucrose increases its stability. Magnesium is deletereous for glucan synthetase in cell-free extracts. Chaotropic agents inactivate glucan synthetase according to their capacity to solubilize and depolymerize biological compounds. Fluoride plays a special role in the activation of glucan synthetase. Its action appears to be dependent on the presence of GTP (or other nucleotides). The role of all these agents on the activity and stability of the enzyme is interpreted in a unified scheme.
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    Archives of microbiology 137 (1984), S. 357-361 
    ISSN: 1432-072X
    Keywords: Yeast ; Saccharomyces cerevisiae ; Killer toxin ; Extracellular glycoprotein
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    Topics: Biology
    Notes: Abstract A total of 13 killer toxin producing strains belonging to the genera Saccharomyces, Candida and Pichia were tested against each other and against a sensitive yeast strain. Based on the activity of the toxins 4 different toxins of Saccharomyces cerevisiae, 2 different toxins of Pichia and one toxin of Candida were recognized. The culture filtrate of Pichia and Candida showed a much smaller activity than the strains of Saccharomyces. Extracellular killer toxins of 3 types of Saccharomyces were concentrated and partially purified. The pH optimum and the isoelectric point were determined. The killer toxins of S. cerevisiae strain NCYC 738, strain 399 and strain 28 were glycoproteins and had a molecular weight of Mr=16,000. The amino acid composition of the toxin type K2 of S. cerevisiae strain 399 was determined and compared with the composition of two other toxins.
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  • 53
    ISSN: 1432-072X
    Keywords: Ammonium export ; Ammonium assimilation ; Glutamine synthetase ; Nitrogen fixation ; Rhizobium sp. 32H1
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    Notes: Abstract The relationship between ammonium assimilation and ammonium export has been studied in free-living, N2-fixing Rhizobium sp. 32H1. After 55 to 67 h of microaerobic growth under a gas phase of 0.2% O2 – 1.0% CO2 – 98.8% Ar high levels of nitrogenase were observed concomitant with a slightly adenylylated glutamine synthetase (GSI) and some glutamine synthetase (GSII) activity. However, after growth of 89 h, or longer, GSI became adenylylated and the level of GSII had decreased. When the gas phase was shifted to 0.2% O2 – 1.0% CO2 – 98.8% N2, a lag was observed before ammonium export could be detected in the 55 to 67 h cultures. No lag in ammonium export was observed in the cultures previously grown for 89 h. The onset of ammonium export in the 55 to 67 h cultures was found to correlate with the adenylylation state of GSI. There appeared to be no correlation between the level of GSII and the export of ammonium. Neither an increase in the adenylylation level of GSI nor ammonium export was observed when the 55 to 67 h cultures were maintained under the Ar gas mixture.
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  • 54
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    Archives of microbiology 125 (1980), S. 89-95 
    ISSN: 1432-072X
    Keywords: Sulfur dioxide ; Sulfite ; Air polluting substances ; Saccharomyces cerevisiae ; Active agent of irreversible cell inactivation
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    Topics: Biology
    Notes: Abstract After a short period of tolerance, living cells of Saccharomyces cerevisiae were irreversibly damaged by low concentrations of sulfite. The length of the period of tolerance and the rate of the damaging effect depended on the concentration on sulfite, pH-value, temperature, the physiological state of the cells, and incubation time. Inhibitors of protein synthesis and mitochondrial ATP synthesis did not alter the deleterious effect of sulfite on living cells. Furthermore, cell damage leading to inhibition of colony formation occured under aerobic as well as under anaerobic conditions. Prior to cell inactivation sulfite induced the formation of respiratory deficient cells. The active agent was shown to be SO2.
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  • 55
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    Archives of microbiology 127 (1980), S. 163-165 
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Arthrobacter ; Corynebacterium ; Anabaena azollae
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    Topics: Biology
    Notes: Abstract Coryneform bacteria were found associated with the nitrogen fixing blue-green alga, Anabaena azollae in the leaf cavity of Azolla caroliniana. Plate counts indicated ca. 7,400±1,900 bacterial cells per mature leaf cavity or approximately 1 bacterial cell for every algal cell. No other type of bacterium was found in these cavities.
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  • 56
    ISSN: 1432-072X
    Keywords: Fluorescent antibody staining ; Nitrogen fixation ; Symbiosis ; Anabaena azollae ; Azolla caroliniana
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    Topics: Biology
    Notes: Abstract Fluorescent antibody staining indicated differences in surface antigenicity in Anabaena azollae cells fresh from the leaf cavities of the fern, Azolla caroliniana, and algae which were isolated and subcultured from this fern. Such results suggest that either changes in antigenicity occur in this phycobiont during culturing or that isolation selects for an antigenically different mutant strain capable of in vitro growth.
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  • 57
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    Archives of microbiology 132 (1982), S. 141-143 
    ISSN: 1432-072X
    Keywords: Phosphoenolpyruvate carboxykinase ; Gluconeogenesis ; Saccharomyces cerevisiae ; Mutant
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    Notes: Abstract A mutant of Saccharomyces cerevisiae lacking phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32) was isolated. The mutant did not grow on gluconeogenic sources except glycerol. The mutation was recessive and apparently affected the structural gene of the enzyme. Intracellular levels of metabolites related to the metabolic situation of the enzyme were not significantly affected after transfer of the mutant from a medium with glycerol to a medium with ethanol as carbon source. In these conditions only AMP decreased 3 to 5 times. A search for mutants affected in the other gluconeogenic enzyme, fructose 1,6 bisphosphatase, remained unsuccessful.
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  • 58
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    Archives of microbiology 129 (1981), S. 146-149 
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Inhibition of tryptophanyl-tRNA synthetase ; Mode of action of tryptophan analogues ; Tryptophan analogue degradation
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    Topics: Biology
    Notes: Abstract The effect of the tryptophan analogue 4-methyltryptophan in Saccharomyces cerevisiae has been investigated. 4-Methyltryptophan inhibits the aminoacylation of tryptophan specific transfer ribonucleic acid (tRNATrp). The mode of inhibition is competitive and the analogue is not charged onto tRNATrp. Thus 4-methyltryptophan application depletes the cells from charged tRNATrp. As a consequence cell growth and protein synthesis are strongly reduced. 4-Methyltryptophan is degraded efficiently in culture media inoculated with the wild type strain; the effects of 4-methyltryptophan were therefore found to be transient.
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  • 59
    ISSN: 1432-072X
    Keywords: Fructose-1,6-bisphosphatase ; Phosphofructokinase ; Antagonistic enzymes ; Glycolytic intermediates ; ATP ; Saccharomyces cerevisiae
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    Notes: Abstract The intracellular levels of adenosine triphosphate and several glycolytic intermediates were determined in Saccharomyces cerevisiae in relation to the presence of the metabolically antagonistic enzymes phosphofructokinase and fructose-1,6-bisphosphatase. Phosphofructokinase is synthesized constitutively in cells grown in the presence of glucose and fructose-1,6-bisphosphatase derepression occurs upon the exhaustion of glucose from the growth medium. Transcriptional regulation of fructose-1,6-bisphosphatase was suggested based on experiments with wild type cells using 8-hydroxyquinoline, a known inhibitor of nuclear transcription, and with the S. cerevisiae mutant strain A364A (ts-136) blocked in the transport of nuclear RNA at non-permissive temperature. The level of phosphofructokinase was reduced more than 25-fold under conditions of high citrate accumulation in an aconitaseless, glutamate requiring mutant strain, MO-1-9B. There was a rapid decrease in the levels of adenosine triphosphate and fructose-1,6-bisphosphate at the end of log-phase of culture growth when both fructose-1,6-bisphosphatase and phosphofructokinase were present in the cells simultaneously. The changes in the levels of key glycolytic intermediates, but not the changes in adenosine triphosphate, during the simultaneous presence of these two enzymes, can be explained without involving any futile cycling.
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  • 60
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    Archives of microbiology 129 (1981), S. 238-239 
    ISSN: 1432-072X
    Keywords: Rhizobium ; Disaccharide ; Bacteroid ; Transport ; Nitrogen fixation
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    Topics: Biology
    Notes: Abstract Slow growing strains of rhizobia appear to lack both uptake systems and catabolic enzymes for disaccharides. In the fast-growing strains of rhizobia there are uptake mechanisms and catabolic enzymes for disaccharide metabolism. In Rhizobium leguminosarum WU 163 and WU235 and R. trifolii WU290, sucrose and maltose uptake appears to be constitutive whereas in R. meliloti WU60 and in cowpea Rhizobium NGR234 uptake of these disaccharides is inducible. There is evidence that there are at least two distinct disaccharide uptake systems in fast-growing rhizobia, one transporting sucrose, maltose and trehalose and the other, lactose. Disaccharide uptake is via an active process since uptake is inhibited by azide, dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone but not by arsenate. Bacteroids of R. leguminosarum WU235 and R. lupini WU8 are unable to accumulate disaccharides.
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  • 61
    ISSN: 1432-072X
    Keywords: Hansenula wingei ; Induction ; Saccharomyces cerevisiae ; Saccharomyces kluyveri ; Sex pheromone ; Sexual agglutinability ; Sexual agglutination
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    Notes: Abstract The yeast, Hansenula wingei has two mating types designated 5 and 21. Cells of each mating type were found to produce mating type-specific sex pheromone which induces sexual agglutinability of the opposite mating type. Crude fractions of these pheromones were prepared by using an Amberlite CG 50 (H+ type) column. The agglutinability-inducing action of the pheromones required glucose as carbon source, but no external nitrogen source. The action of the pheromones was inhibited by 5 μg/ml cycloheximide. The optimum pH for the pheromone action was 4.0. α Pheromones of Saccharomyces cerevisiae and Saccharomyces kluyveri induced sexual agglutinability of 5 mating type cells but did not that of 21 mating type cells. a Pheromones of the Saccharomyces yeasts had no effect on both 5 and 21 mating type cells. The sex pheromones of H. wingei had no effect on the sexual agglutinability of inducible a cells of S. cerevisiae. From the experimental results obtained so far, we propose to call 5 and 21 mating types in H. wingei a and α mating types, respectively.
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  • 62
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    Archives of microbiology 130 (1981), S. 38-43 
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Gene expression ; Regulation ; Messenger RNA ; Transcription ; Klebsiella pneumoniae
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    Notes: Abstract Nitrogenase messenger RNA synthesis in Klebsiella pneumoniae was determined by labelling cells with (3H)uracil and isolating total RnA, which was then hybridized to filterbound recombinant plasmid pSA30 DNA carrying the nitrogenase structural genes nifH, D, and K. Derepression of nitrogenase mRNA starts 1.5 h before the onset of nitrogenase activity (as measured by acetylene reduction). Exposure of nif-derepressed cultures to either NH 4 + , air, or high temperatures (39° C) results in a rapid decrease of the synthesis rates both of nitrogenase mRNA and nitrogenase polypeptides. Nitrogenase mRNA is remarkably stable. After blocking transcription with rifampicin, hybridizable and actively translatable nitrogenase mRNA survives with an average half-life of 18 min. Half-lives are considerably shorter when rifampicin-inhibited cultures are simultaneously shifted to conditions which are non-permissive for nitrogenase synthesis, pointing to some posttranscriptional influence on nitrogenase mRNA stability. In all experiments performed there was no evidence for uncoupling of nitrogenase mRNA synthesis from nitrogenase mRNA translation, indicating that nitrogenase synthesis is regulated solely by transcriptional control.
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  • 63
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Bud scar ; Scar ring ; Glucan ; Chitin ; Mannan ; Cytology ; Electron and X-ray diffractions ; Physico-chemical characterization
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    Notes: Abstract Scar rings (SR) from scarless cells at the early stages of budding and mature bud scars from Saccharomyces cerevisiae isolated by both chemical and enzymic treatment of cell walls were observed by selected-area electron diffraction (SAED), X-ray diffraction and electron microscopy with simultaneous physico-chemical characterization (including molar mass, intrinsic viscosity and crystallite size) of α-chitin and glucan. The SR, composed of glucan with strong 0.608; 0.397 and 0.293 nm X-ray reflections, was formed at the start of budding. The SAED patterns of α-chitin both in the adjacent circular zone and in the parts of newly formed primary septum (PS), observed when the development of the PS started, did not differ from those of α-chitin in the single mature bud scar. The bud scar consisted of α-chitin, glucan and mannan and their content, as well as the crystallite size of chitin, depended on the mode of preparation.
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  • 64
    ISSN: 1432-072X
    Keywords: Rhizobium trifolii ; Symbiosis ; Nodulation ; Nitrogen fixation ; Symbiotic genes ; Reiterated sequences ; Plasmid
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    Notes: Abstract A Rhizobium trifolii symbiotic plasmid specific gene library was constructed and the physical organisation of regions homologous to nifHDK, nifA and nod genes was determined. These symbiotic gene regions were localised to u 25 kb region on the sym-plasmid, pPN1. In addition four copies of a reiterated sequence were identified on this plasmid, with one copy adjacent to nifH. No rearrangement of these reiterated sequences was observed between R. trifolii bacterial and bacteroid DNA. Analysis of a deletion derivative of pPN1 showed that these sequences were spread over a 110 kb region to the left of nifA.
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  • 65
    ISSN: 1432-072X
    Keywords: Agglutination substance ; Cell-cell recognition ; Glycoprotein ; Mating ; Saccharomyces cerevisiae ; Sexual agglutinability ; Yeast
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    Notes: Abstract An a-mating-type-specific substance responsible for sexual agglutination was purified to 397-times in specific activity (units/mg protein) from the cytoplasm of a-mating type cells. The purified substance gave a single band stained with PAS reagent but not with both Coomassie brilliant blue and silver staining reagent by polyacrylamide gel electrophoresis in the presence of 8 M urea. However, incorporation of [35S]methionine and Lowry reaction clearly indicate that the substance is a glycoprotein. The substance specifically masked sexual agglutinability of cells of the opposite mating type α, indicating univalent action. The substance is a glycoprotein with a carbohydrate content of 90%, a pI of 4.5, and a molecular weight of 130,000. The substance was inactivated by 2-mercaptoethanol and proteolytic enzymes but not by glycolytic enzymes. The substance formed a complementary complex having no biological activity when mixed with α-agglutination substance from the wall or cytoplasm of α-cells in vitro.
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  • 66
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    Archives of microbiology 131 (1982), S. 298-301 
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    Keywords: Yeast ; Protoplast ; Compartmentation ; Vacuole ; Trehalose ; Trehalase ; Carbohydrate metabolism ; Saccharomyces cerevisiae
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    Notes: Abstract Protoplasts of Saccharomyces cerevisiae synthesized and degraded trehalose when they were incubated in a medium containing traces of glucose and acetate. Such protoplasts were gently lyzed by the polybase method and a particulate and soluble fraction was prepared. Trehalose was found in the soluble fraction and the trehalase activity mostly in the particulate fraction which also contained the vacuoles besides other cell organelles. Upon purification of the vacuoles, by density gradient centrifugation, the specific activity of trehalase increased parallel to the specific content of vacuolar markers. This indicates that trehalose is located in the cytosol and trehalase in the vacuole. It is suggested that trehalose, in addition to its role as a reserve may also function as a protective agent to maintain the cytosolic structure under conditions of stress.
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  • 67
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    Archives of microbiology 133 (1982), S. 242-248 
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    Keywords: Saccharomyces cerevisiae ; Tryptophan degradation to tryptophol ; Degradation-defective mutant strain ; Aromatic aminotransferases ; Tryptophan accumulation
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    Notes: Abstract Tryptophan was found to be degraded in Saccharomyces cerevisiae mainly to tryptophol. Upon chromatography on DEAE-cellulose two aminotransferases were identified: Aromatic aminotransferase I was constitutively synthesized and was active in vitro with tryptophan, phenylalanine or tyrosine as amino donors and pyruvate, phenylpyruvate or 2-oxoglutarate as amino acceptors. The enzyme was six times less active with and had a twenty times lower affinity for tryptophan (K m=6 mM) than phenylalanine or tyrosine. It was postulated thus that aromatic aminotransferase I is involved in vivo in the last step of tyrosine and phenylalanine biosynthesis. Aromatic aminotransferase II was inducible with tryptophan but also with the other two aromatic amino acids either alone or in combinations. With tryptophan as amino donor the enzyme was most active with phenylpyruvate and not active with 2-oxoglutarate as amino acceptor; its affinity for tryptophan was similar as for the other aromatic amino acids (K m=0.2–0.4 mM). Aromatic aminotransferase II was postulated to be involved in vivo mainly in the degradation of tryptophan, but may play also a role in the degradation of the other aromatic amino acids. A mutant strain defective in the aromatic aminotransferase II (aat2) was isolated and its influence on tryptophan accumulation and pool was studied. In combination with mutations trp2 fbr, aro7 and cdr1-1, mutation aat2 led to a threefold increase of the tryptophan pool as compared to a strain with an intact aromatic aminotransferase II.
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  • 68
    ISSN: 1432-072X
    Keywords: Ammonia assimilation ; Lichen symbioses ; Nitrogen fixation ; 15N kinetics ; Peltigera canina
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    Notes: Abstract On following N2-incorporation and subsequent metabolism in the lichen Peltigera canina using 15N as tracer, it was found, over a 30 min period, that greatest initial labelling was into NH 4 + followed by glutamate and the amide-N of glutamine. Labelling of the amino-N of glutamine, aspartate and alanine increased slowly. Pulse-chase experiments using 15N confirmed this pattern. On inhibiting the GS-GOGAT pathway using l-methionine-dl-sulphoximine and azaserine, 15N enrichment of glutamate, alanine and aspartate continued although labelling of glutamine was undetectable. From this and enzymic data, NH 4 + assimilation in the P. canina thallus appears to proceed via GS-GOGAT in the cyanobacterium and via GDH in the fungus; aminotransferases were present in both partners. The cyanobacterium assimilated 44% of the 15N2 fixed; the remainder was liberated almost exclusively as NH 4 + and then assimilated by fungal GDH.
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  • 69
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    Archives of microbiology 135 (1983), S. 103-109 
    ISSN: 1432-072X
    Keywords: RNA polymerase ; Transcription ; Nitrogen fixation ; Symbiosis ; Rhizobium
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    Topics: Biology
    Notes: Abstract DNA-dependend RNA polymerase (EC 2.7.7.6) from Rhizobium japonicum was purified. The subunit structure was found to be ββ′α2σ, with the following apparent molecular weights determined by electrophoresis: M r (β and β') 150,000 each, M r (σ) 96,000, M r (α) 40,000, M r (holoenzyme) 490,000, M r (core enzyme) 380,000. The recovery of σ was 28%. RNA polymerase from aerobically grown R. japonicum cells and from nitrogen-fixing cells have the same electrophoretic properties suggesting that no chemical modification of the enzyme occurs when cells undergo this metabolic differentiation. The enzyme is Mg2+-dependent, rifampicin-sensitive, and has optimal activity at alkaline pH (8–10) and at 35–40° C. It binds strongly to bacteriophage T7 promoters, weakly to antibiotic resistance genes, and not at all to cloned R. japonicum nif DNA. Preliminary in vitro transcription experiments, including nif DNA as template, revealed that additional factors may be required for selective transcription from promoters.
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  • 70
    ISSN: 1432-072X
    Keywords: α Pheromone ; Cell cycle ; G1 arrest ; Hansenula wingei ; Saccharomyces cerevisiae ; Shmoo
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    Notes: Abstract The cell cycle of a (5) mating type cells of Hansenula wingei was arrested in the G1 phase by α pheromone of Saccharomyces cerevisiae but not by α(21) pheromone of H. wingei, although both the α pheromones are known to induce sexual agglutination ability of a mating type cells of H. wingei. Cells of α mating type of H. wingei became shmooed or arrested in the G1 phase in response to neither a pheromone of H. wingei nor α pheromone of S. cerevisiae.
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  • 71
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    Archives of microbiology 136 (1983), S. 219-221 
    ISSN: 1432-072X
    Keywords: Xanthobacter ; Nitrogen fixation ; Oxygen sensitivity ; Nitrogen metabolism ; Glutamine synthetase ; Glutamate synthase
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    Notes: Abstract N2-fixation was investigated in the chemoautotrophic hydrogen bacterium Xanthobacter H4-14. N2-fixing batch cultures of this organism could only be grown at pO2 values of around 0.02 bar, and in continuous culture dissolved oxygen tensions above 16 μM were found to inhibit N2-fixation. Xanthobacter H4-14 utilized a variety of amino acids, nitrate and ammonia as nitrogen sources. Cell-free extracts from steady-state continuous cultures of ammonia grown, nitrate grown and N2-fixing Xanthobacter were assayed for the presence of ammonia assimilation enzymes. No alanine dehydrogenase or glutamate dehydrogenase activity was detected. Ammonia was assimilated exclusively via the glutamine synthetase/glutamate synthase pathway, irrespective of the extracellular concentration of ammonia.
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  • 72
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    Archives of microbiology 124 (1980), S. 161-167 
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Photosynthesis ; Green alga ; Chl a and b ; DCMU ; Light and O2 dependency
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    Topics: Biology
    Notes: Abstract A unicellular alga which can grow in the light without a combined nitrogen source was isolated from a hot spring. The cells were almost spherical, usually 5–10 μm in diameter. Absorption spectra of the watersoluble pigments and of the acetone-extracted ones revealed the existence of chlorophyll a and b and the absence of phycobilins. Thin sections examined by electron microscopy revealed an eukaryotic organization with features typical of the coccoid green algae (the Chlorococcales). Cells divided by internal cytokinesis and subsequent liberation of daughter cells from the parental wall, in a way similar to Chlorella. The alga reduced acetylene to ethylene and incorporated 15N2 into cell protoplasm when incubated in a low oxygen atmosphere. Nitrogenase activity was light-dependent, microaerophilic and thermophilic. Although the association of symbiotic nitrogen fixing prokaryotes with the cells may still be possible, any such organisms have not so far been detected.
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  • 73
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    Archives of microbiology 127 (1980), S. 115-118 
    ISSN: 1432-072X
    Keywords: Proteus mirabilis ; Serratia marcescens ; Erwinia herbicola ; Nitrogen fixation ; nif genes ; his genes ; Plasmids
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    Topics: Biology
    Notes: Abstract Plasmid pRD1, an R plasmid of the P incompatibility group which carries his and nif genes from Klebsiella pneumoniae in addition to drug resistance markers derived from RP4, was transferred to His- mutants of Serratia marcescens, Erwinia herbicola and Proteus mirabilis. His+ transconjugants were obtained at low but different frequencies according to recipient genus. Transconjugants all acquired the drug resistance, and were Nif+ in S. marcescens and E. herbicola, having acetylene-reducing activities of the same order of magnitude as the parent K. pneumoniae and fixing 15N2. No evidence for nif expression in P. mirabilis transconjugants was obtained though the nif genes were present.
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  • 74
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Catabolite repression and inactivation ; Inhibition of protease B
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    Notes: Abstract Catabolite inactivation of fructose-1,6-bisphosphatase, isocitrate lyase, phosphoenolpruvate carboxykinase and malate dehydrogenase in intact cells could be prevented by phenylmethylsulfonyl fluoride added 40 min prior to the addition of glucose. Protein synthesis, fermentative and respiratory activity and catabolite repression were not affected. Elimination of catabolite inactivation by the addition of PMSF revealed that catabolite repression started at different times for different enzyme.
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  • 75
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    Archives of microbiology 132 (1982), S. 219-224 
    ISSN: 1432-072X
    Keywords: Rhizobium ; Nitrogen fixation ; Nodules ; Soybean
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    Notes: Abstract Several mutants defective in nodulation were isolated from Rhizobium japonicum strains 3I1b110 and 61A 76. Mutants of class I do not form nodules after incubation with soybean [Glycine max (L.) Merrill] for 17 days, but will do so by 28 days. When host plants other than G. max are infected with several of these strains, there is no detectable difference in the time of nodulation or size of nodules as compared to the wild type. Two mutants of class I (i. e., SM1 and SM2) have been shown previously to be altered in the lipopolysaccharide portion of their cell wall. Mutants of class II are not slow to nodulate but form fewer nodules than the wild type on all the host plants tested. Mutants of class III are unable to form nodules. Some bacteriophage-resistant mutants, altered in cell surface structure, fall into this class. Two mutants of class III do not bind to soybean roots.
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  • 76
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    Archives of microbiology 132 (1982), S. 236-240 
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    Keywords: α Pheromone ; Cycloheximide ; Inducible a strain ; Phenylmethylsulfonyl fluoride ; Saccharomyces cerevisiae ; Sexual agglutinability ; Temperature-sensitive
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    Notes: Abstract When α pheromone-pretreated cells of an inducible a strain of Saccharomyces cerevisiae carrying the inducible gene saa1 were incubated in a growth medium at 28°C, induction of sexual agglutinability began after a 10 min lag period. If the cells were incubated at 38°C during the lag period, no induction occurred even after incubation at 28°C. Contrary to this, if the cells were incubated at 28°C during the lag period, almost complete induction occurred, even after transfer to 38°C. Temperature shift experiments revealed that 5 min incubation at 28°C was necessary for the initiation of the temperature-sensitive period and further 5 min incubation for the completion of the period. The temperature-sensitive period was sensitive to phenylmethylsulfonyl fluoride.
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  • 77
    ISSN: 1432-072X
    Keywords: Candida utilis ; Saccharomyces cerevisiae ; Zygosaccharomyces bailii ; Compartmentation ; Vacuoles ; Internal pH ; Phosphate ; Glycolysis ; Nuclear magnetic resonance
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    Notes: Abstract 31P NMR spectra were obtained from suspensions of Candida utilis, Saccharomyces cerevisiae and Zygosaccharomyces bailii grown aerobically on glucose. Direct introduction of substrate into the cell suspension, without interruption of the measurements, revealed rapid changes in pH upon addition of the energy source. All 31P NMR spectra of the yeasts studied indicated the presence of two major intracellular inorganic phosphate pools at different pH environments. The pool at the higher pH was assigned to cytoplasmic phosphate from its response to glucose addition and iodoacetate inhibition of glycolysis. After addition of substrate the pH in the compartment containing the second phosphate pool decreased. A parallel response was observed for a significant fraction of the terminal and penultimate phosphates of the polyphosphate observed by 31P NMR. This suggested that the inorganic phosphate fraction at the lower pH and the polyphosphates originated from the same intracellular compartment, most probably the vacuole. In this vacuolar compartment, pH is sensitive to metabolic conditions. In the presence of energy source a pH gradient as large as 0.8 to 1.5 units could be generated across the vacuolar membrane. Under certain conditions net transport of inorganic phosphate across the vacuolar membrane was observed during glycolysis: to the cytoplasm when the cytoplasmic phosphate concentration had become very low due to sugar phosphorylation, and into the vacuole when the former concentration had become high again after glucose exhaustion.
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  • 78
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    Archives of microbiology 133 (1982), S. 172-177 
    ISSN: 1432-072X
    Keywords: Beggiatoa ; Nitrogen fixation ; Acetylene reduction ; Nitrate assimilation ; Microaerobic ; Isolation of marine strains
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    Topics: Biology
    Notes: Abstract Four newly isolated marine strains of Beggiatoa and five freshwater strains were tested for nitrogen fixation in slush agar medium. All strains reduced acetylene when grown microaerobically in media containing a reduced sulfur source and lacking added combined nitrogen. The addition of 2 mmol N, as nitrate or ammonium salts, completely inhibited this reduction. Although not optimized for temperature or cell density, acetylene reduction rates ranged from 3.2 to 12 nmol·mg prot-1 min-1. Two freshwater strains did not grow well or reduce acetylene in medium lacking combined nitrogen if sulfide was replaced by thiosulfate. Two other strains grew well in liquid media lacking both combined nitrogen and reduced sulfur compounds but only under lowered concentrations of air. All freshwater strains grew well in medium containing nitrate as the combined nitrogen source. Since they did not reduce acetylene under these conditions, we infer that they can assimilate nitrate.
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  • 79
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    Archives of microbiology 133 (1982), S. 312-317 
    ISSN: 1432-072X
    Keywords: Rhizobium japonicum ; Rhizobium leguminosarum ; Formate metabolism ; Formate dehydrogenase ; Nitrogen fixation ; Nitrogenase ; Bacteroids ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Formate metabolism supported nitrogen-fixation activity in free-living cultures of Rhizobium japonicum. However, formate0dependent nitrogense activity was observed only in the presence of carbon sources such as glutamate, ribose or aspartate which by themselves were unable to support nitrogenase activity. Formate-dependent nitrogenase activity was not detected in the presence of carbon sources such as malate, gluconate or glycerol which by themselves supported nitrogenase activity. A mutant strain of R. japonicum was isolated that was unable to utilise formate and was shown to lack formate dehydrogenase activity. This mutant strain exhibited no formate-dependent nitrogenase activity. Both the wild-type and mutant strains nodulated soybean plants effectively and there were no significant differences in the plant dry weight or total nitrogen content of the respective plants. Furthermore pea bacteroids lacked formate dehydrogenase activity and exogenously added formate had no stimulatory effect on the endogenous oxygen uptake rate. The role of formate metabolism in symbiotic nitrogen fixation is discussed.
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  • 80
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrogenase regulation ; Glutamine synthetase ; Methionine suofoximine ; Rhodospirillaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methionine sulfoximine (MSX), an irreversible inhibitor of glutamine synthetase of Rhodopseudomonas palustris restored nitrogenase activity to cells in which nitrogenase had been completely inhibited by ammonia switch-off. After addition of MSX, there was a lag period before nitrogenase activity was fully restored. During this lag, glutamine synthetase activity progressively decreased, and near the time of its complete inhibition, nitrogenase activity resumed. Nitrogenase switch-off by ammonia thus required active glutamine synthetase. Glutamine itself caused nitrogenase inhibition whose reversal by MSX depended on the relative ratio of MSX to glutamine. Unlike ammonia, glutamine inhibited nitrogenase under conditions where glutamine synthetase activity was absent. This indicates that glutamine is the effector molecule in nitrogenase switch-off, for instance by interacting with the enzymatic system for Fe protein inactivation. The effects of glutamine and MSX were also dependent on the culture age. Possible explanation for this and for the competitive effects are a common binding site within the regulatory apparatus for nitrogenase, or, in part, within a common transport system. Some observations with MSX were extended to Rhodopseudomonas capsulata and agreed with those in R. palustris.
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  • 81
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    Archives of microbiology 134 (1983), S. 64-67 
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Anaerobic growth ; Hungate technique ; Tween 80 ; Ergosterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Saccharomyces cerevisiae, Nontrachet strain 522 was successfully grown anaerobically on various glucose concentrations in Yeast Nitrogen Base (YNB) medium (pH 3.5) prepared under an atmosphere of carbon dioxide (CO2). This growth occurred in the absence of Tween 80 and ergosterol. The medium, prepared using the Hungate technique for cultivation of strictly anaerobic bacteria, contained the reducing agent cysteine·HCl·H2O (0.03%). Anaerobic growth was stimulated by the addition of Tween 80 and ergosterol to the anaerobic medium.
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  • 82
    ISSN: 1432-072X
    Keywords: Azotobacter vinelandii ; Continuous culture ; Oxygen control ; Nitrogen fixation ; Respiratory protection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Azotobacter vinelandii strain OP was grown in continuous culture at various dissolved oxygen concentrations of air (100% air saturation of the medium=225 ±14 μM O2). Sucrose was added as carbon source and either dinitrogen or ammonia as nitrogen sources. Irrespective of the nitrogen source steady state cultures showed the following general responses with dissolved oxygen concentrations increasing from about 1% to 30% air saturation: (i) cell protein levels, (ii) the amount of cell protein formed per sucrose consumed as well as (iii) nitrogenase activity decreased by at least a factor of two while (iv) cellular respiration increased. At higher oxygen concentrations the parameters changed only slightly, if at all. Increasing the sucrose concentration in the inflowing medium (s R) from 3 g/l to 15 g/l increased the total level of cellular respiration with nitrogen-fixing cultures but was more pronounced with ammonium-assimilating cultures. With nitrogen-fixing cultures cell protein levels increased five-fold while the ratio of protein formed per sucrose consumed as well as cellular nitrogenase activity remained unaffected. With ammonium-assimilating cultures the cell protein level was only doubled and the level of cell protein formed per sucrose consumed was decreased at the higher s R. Increasing the dilution rate at a constant oxygen concentration of 45% air saturation resulted in an almost parallel increase of both cellular respiratory and nitrogenase activity at low and moderate dilution rates. At high dilution rates nitrogenase activity increased steeply over the respiratory activity. Nitrogen-fixing cultures adapted to various oxygen concentrations were subjected to oxygen stress by increasing the oxygen concentration for 7 min. In all cases, this resulted in a complete inhibition (‘switch-off’) of nitrogenase activity. Upon restoration of the original oxygen concentration nitrogenase activity returned to a decreased level. The discussion arrives at the conclusion that some of the results are incompatible with the concept of respiratory protection of nitrogenase.
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  • 83
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    Archives of microbiology 134 (1983), S. 171-174 
    ISSN: 1432-072X
    Keywords: Acetate growth medium ; Anti-microtubule agent ; Bud initiation ; Ethyl N-phenylcarbamate ; Meiosis ; Mitotic cell cycle ; Saccharomyces cerevisiae ; Sporulation induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When diploid cells of Saccharomyces cerevisiae were incubated in acetate growth media containing 2.5 mM ethyl N-phenylcarbamate (EPC), bud initiation was inhibited preferentially, and eventually overgrown, unbudded cells accumulated. During subsequent incubation, meiosis and ascospore formation occurred at high frequencies. The behavior of EPC-treated cells was essentially the same as that of cells transferred to a starvation sporulation medium. EPC thus has a pronounced effect on the mitotic growth of yeast cells, which leads to meiotic development. Our observations indicate that EPC has a decisive function in the initiation of meiosis in rich growth media.
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  • 84
    ISSN: 1432-072X
    Keywords: Nucleotide pools ; Continuous cultivation ; Synchronized growth ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High pressure liquidd chromatography has been used to study the acid soluble nucleotide pool of Saccharomyces cerevisiae under different conditions of growth. ATP, ADP, AMP, NAD, GTP, UTP, UDP, CTP, CDP, and UDP-sugars plus UMP could be separated and were found in concentrations higher than 0.1 μmol per g yeast cell dry weight (=detection limit). During glucose-limited continuous culture the levels of individual nucleotides depended on the growth rate, which was most pronounced with pyrimidine (uridine, cytidine) nucleotides. The energy charge (E.C.) remained high (0.9) at all growth rates (0.07–0.3 h-1). During synchronized growth at a constant growth rate (0.11 h-1) almost all nucleotide levels and the E.C. remained at constant values with the only exception of UDP-sugars and UMP of which increased levels were found during the phase of budding. Under conditions of metabolic stress (addition of antimycin A, deoxyglucose plus iodoacetate) pronounced changes in the levels of purine (adenine and guanine) nucleotides and the E.C. were observed. All other nucleotides were less influenced by these conditions. Only under these conditions IMP accumulation was observed. The results strongly argue against the significance of purine nucleotide or E.C. measurements under viable conditions. In contrast, changes in the levels of pyrimidine nucleotides seem to be indicative of changes in the flux through the metabolic pathways where they act as coenzymes.
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  • 85
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    Archives of microbiology 136 (1983), S. 81-83 
    ISSN: 1432-072X
    Keywords: Ammonia production ; Anabaena ; Cyanobacteria ; Nitrate reductase ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the filamentous heterocystous cyanobacterium Anabaena sp. strain ATCC 33047 dinitrogen fixation and nitrate reduction are mutually exclusive processes. Nitrate promotes nitrate reductase synthesis and represses nitrogenase formation. Inhibition of ammonium assimilation by l-methionine-d,l-sulfoximine (MSX) alleviates the repressive effect of nitrate on nitrogenase synthesis, thus indicating that the nitrate effect is indirect through metabolites generated from the ammonium derived from nitrate reduction. In MSX-treated cells both nitrate reduction and dinitrogen fixation take place simultaneously, although at different sites of the filament, without any apparent competition for the required reducing power. The MSX-treated Anabaena cells generate ammonium from both nitrate and dinitrogen, simultaneously.
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  • 86
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    Archives of microbiology 138 (1984), S. 212-216 
    ISSN: 1432-072X
    Keywords: Denitrification ; Nitrate respiration ; Nitrous oxide reduction ; Nitrogen fixation ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrous oxide reduction can consistently be demonstrated with high activities in cells of Azospirillum brasilense Sp 7 which are grown anaerobically in the presence of low amounts of nitrite. Azospirillum can even grow anaerobically with nitrous oxide in the absence of any other respiratory electron acceptor. Nitrous oxide reduction by Azospirillum is inhibited by acetylene, amytal and weakly by carbon monoxide. Azospirillum converts nitrous oxide to molecular nitrogen without the formation of ammonia. The cells must, therefore, be supplied with ammonia from nitrogen fixation during anaerobic growth with nitrous oxide. When no other nitrogen compound besides nitrous oxide is available in the medium, the bacteria synthesize nitrogenase from protein reserves in about 2 h. Nitrogenase synthesis is blocked by chloramphenicol under these conditions. In contrast, the addition of nitrate or nitrite to the medium represses the synthesis of nitrogenase. Nitrous oxide reduction by Azospirillum and other microorganisms is possibly of ecological significance, because the reaction performed by the bacteria may remove nitrous oxide from soils.
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  • 87
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    Archives of microbiology 130 (1981), S. 96-100 
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrate respiration ; Denitrification ; Assimilatory nitrate reduction ; Dissimilatory nitrate reduction ; Acetylene reduction ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Azospirillum spp. participate in all steps of the nitrogen cycle except nitrification. They can fix molecular nitrogen and perform assimilatory nitrate reduction and nitrate respiration. Culture conditions have been defined under which nitrate is used both as terminal respiratory electron acceptor and as nitrogen source for growth. Nitrate and, possibly to a very limited extent, nitrite, but not sulfate, iron or fumarate support anaerobic respiration. Under anaerobic conditions, nitrate can also supply energy for nitrogen fixation but without supporting growth. Nitrate-dependent nitrogenase activity lasts only for 3–4 h until the enzymes of assimilatory nitrate reduction are synthesized. Nitrite accumulates during this period and inhibits nitrogenase activity at concentrations of about 1 mM.
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  • 88
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    Archives of microbiology 140 (1984), S. 215-217 
    ISSN: 1432-072X
    Keywords: Glutathione reductase ; Cyanobacteria ; Nostoc muscorum ; O2 protection ; Glutathione ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutathione reductase activity was detected and characterized in heterocysts and vegetative cells of the cyanobacterium Nostoc muscorum. The activity of the enzyme varied between 50 and 150 nmol reduced glutathione· min-1·mg protein-1, and the apparent Km for NADPH was 0.125 and 0.200 mM for heterocysts and vegetative cells, respectively. The enzyme was found to be sensitive to Zn+2 ions, however, preincubation with oxidized glutathione rendered its resistance to Zn+2 inhibition. Nostoc muscorum filaments were found to contain 0.6–0.7mM glutathione, and it is suggested that glutathione reductase can regenerate reduced glutathione in both cell types. The combined activity of glutathione reductase and isocitrate dehydrogenase in heterocysts was as high as 18 nmol reduced glutathione·min-1·mg protein-1. A relatively high superoxide dismutase activity was found in the two cell types; 34.2 and 64.3 enzyme units·min-1·mg protein-1 in heterocysts and vegetative cells, respectively. We suggest that glutathione reductase plays a role in the protection mechanism which removes oxygen radicals in the N2-fixing cyanobacterium Nostoc muscorum.
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  • 89
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    Archives of microbiology 124 (1980), S. 285-287 
    ISSN: 1432-072X
    Keywords: Yeast ; Saccharomyces cerevisiae ; Heat killing ; Membrane damage ; Genetic damage ; Growth temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The resistance of exponentially growing yeast cells to killing by exposure to 52°C increased markedly as the growth temperature was increased. Identical killing curves were obtained for cells suspended in growth medium or in 0.9% saline. Cells resistant to killing at 52°C were quite sensitive to killing at slightly higher temperatures. These results suggest a primary role for membrane damage in the mechanism of heat killing.
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  • 90
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    Archives of microbiology 132 (1982), S. 333-337 
    ISSN: 1432-072X
    Keywords: Anabaena variabilis Kütz ; 14C-prelabeled blue-green algae ; Interaction respiration/photosynthesis ; CO2 exchange ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prelabeled Anabaena variabilis Kütz. evolves 14CO2 in the light with KCN and DCMU (2,4-dichlorophenyl-1,1-dimethylurea) present, comparable to the dark control without inhibitors added. Double-reciprocal plots of CO2 release vs. light intensity with either KCN or KCN+DCMU present result in two straight lines intersecting at the ordinate. Apparently, reducing equivalents originating from carbohydrate catabolism are channeled into the photosynthetic electron-transport chain, competing for electrons from photosystem II. Under these conditions, the CO2 release is accompanied by a light-dependent oxygen uptake, presumably due to oxygen-reducing photosystem-I activity while ribulose-bisphosphate carboxylase is inhibited by KCN. Comparing nine blue-green algae it was shown that only nitrogen-fixing species release substantial amounts of CO2 in the light with KCN or KCN+DCMU present. This release is particularly obvious with Anabaena variabilis Kütz. under nitrogen-fixing conditions, but small when the alga is grown with combined nitrogen. We conclude that nitrogen-fixing species share a common link between respiratory and photosynthetic electron transport. The physiological role may be electron supply of nitrogenase by photosystem I.
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  • 91
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    Archives of microbiology 133 (1982), S. 6-10 
    ISSN: 1432-072X
    Keywords: Rhodospirillaceae ; Rhodopseudomonas globiformis ; Nitrogen metabolism ; Nitrogen fixation ; Glutamine synthetase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas globiformis strain 7950 grew with a variety of amino acids, urea, or N2 as sole nitrogen sources. Cultures grown on N2 reduced acetylene to ethylene; this activity was absent from cells grown on nonlimiting NH 4 + . Glutamate dehydrogenase could not be detected in extracts of cells of strain 7950, although low levels of an alanine dehydrogenase were present. Growth ofR. globiformis on NH 4 + was severely inhibited by the glutamate analogue and glutamine synthetase inhibitor, methionine sulfoximine. High levels of glutamine synthetase (as measured in the γ-glutamyl transferase assay) were observed in cell extracts of strain 7950 regardless of the nitrogen source, although N2 and amino acid grown cells contained somewhat higher glutamine synthetase contents than cells grown on excess NH 4 + . Levels of glutamate synthase inR. globiformis were consistent with that reported from other phototrophic bacteria. Both glutamate synthase and alanine dehydrogenase were linked to NADH as coenzyme. We conclude thatR. globiformis is capable of fixing N2, and assimilates NH 4 + primarily via the glutamine synthetase/glutamate synthase pathway.
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  • 92
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Water stress ; Taxonomy ; DNA ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of desiccation-tolerant coccoid cyanobacteria, Chroococcus S24, a marine form, and Chroococcus N41, a cryptoendolith isolated from a hot-desert rock, have been characterized. The mol % DNA base compositions of the strains are 47.1 and 48.9% respectively. Plasmid DNA was not detected in either strain. The pigment contents and nutritional characteristics of the strains are identical. Both lack phycoerythrinoid pigments and, in culture, behave as slow-growing halotolerant marine forms with elevated requirements for Na+, Cl−, Mg2+ and Ca2+. Sucrose was the only carbon source of those tested that supported photoheterotrophic growth. Each strain synthesizes nitrogenase under anaerobic conditions but not in air. Morphologically the two strains are indistinguishable. They are considered to be independent isolates of the same cyanobacterial species. Chroococcus N41 was studied in detail with the electron microscope. When brought to equilibrium at matric water potentials of-168 MPa and lower (to-673 MPa=c0.12a w) the protoplast shrinks, but the cells maintain the same size and diameter as those at-2,156 kPa (MN medium; control); the sheath expands and remains attached to the cell wall outer membrane by fibrils. The cell wall, cell membrane, thylakoid membranes, cyanophycin granules and carboxysomes appeared intact in desiccated cells.
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  • 93
    ISSN: 1432-072X
    Keywords: Glycoprotein ; Inducible strains ; Saccharomyces cerevisiae ; Sexual agglutinability ; Tunicamycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of tunicamycin (TM) on the sexual agglutinability and zygote formation of Saccharomyces cerevisiae were studied using the two kinds of haploid strains, inducible and constitutive for sexual agglutinability. Induction of sexual agglutinability by opposite mating type sex pheromone of inducible strains was inhibited by TM in α mating type but not in a mating type. The recovery by temperature-shift-down from the temperature-suppressed sexual agglutinability of constitutive strains was enhanced by TM in a mating type but rather inhibited in α mating type. Pretreatment with TM of constitutive strains enhanced sexual agglutinability in a mating type but not in α mating type. The above-mentioned a-mating-type-specific agglutinability-enhancing actions of TM were discussed in relation to the action mechanism of α pheromone which induces or enhances the sexual agglutinability of a cells. Zygote formation was inhibited by TM in both constitutive and inducible strains at concentrations which showed only partially inhibitory effect on sexual agglutinability.
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  • 94
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    Theoretical chemistry accounts 60 (1982), S. 579-587 
    ISSN: 1432-2234
    Keywords: Nitrogen fixation ; Nitrogen complexes ; Carbon monoxide complexes ; Electronic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract MNDO method is used to study the interaction of nitrogen and carbon monoxide molecules with a proton, hydrogen atom, hydride ion, hydrogen molecule ion and hydrogen molecule. Predicted geometries and heats of reaction of different complexes are presented. The wave functions are analyzed in terms of ground state charge distributions and overlap populations. Electronic effects accompanying complexation are also discussed.
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  • 95
    ISSN: 1573-1561
    Keywords: Leptopilinaheterotoma ; Hymenoptera ; Eucoilidae ; Saccharomyces cerevisiae ; host-habitat searching ; chemoreception ; fermentation products ; ethanol ; ethyl acetate ; acetaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Chemical stimuli play an important role in the process of searching for a host habitat by parasitic wasps. Volatile compounds originating from host habitats and/or hosts are the cues that enable such a location.Leptopilina heterotoma, a larval parasite ofDrosophila, is attracted to the food of its host, baker's yeast. Analysis of the fermentation products of baker's yeast, using a mass spectrometer, and olfactometer studies indicate that three fermentation products of this yeast, the main component of the host habitat in our laboratory, attractL. heterotoma: ethanol (5%), ethyl acetate (10−2, 10−3%), and acetaldehyde (1%). A combination of these three compounds, however, cannot compete with baker's yeast in attracting the parasites. Thus other factors, such as different compounds, concentrations, and/or combinations, also, play a role and remain to be tested.Leptopilina heterotoma does not use host-related olfactory cues in long-distance habitat location as it cannot distinguish between host habitat and host habitat with hosts.
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  • 96
    ISSN: 1432-2048
    Keywords: Nitrogen fixation ; Nodule development ; Senescence (nodules) ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cowpea (Vigna unguiculata (L.) Walp cv. Vita 3) seedlings inoculated with Rhizobium strain CB756 were cultured with their root systems maintained in air or in Ar: O2 (80:20, v/v) during early nodule development (up to 24 d after sowing). Compared with those in air, seedlings in Ar:O2 showed progressive N deficiency with inhibited shoot growth, reduced ribulose-1,5-bisphosphate carboxylase and total protein levels and loss of chlorophyll in the leaves. Nodule initiation, differentiation of infected and uninfected nodule tissues and the ultrastructure of bacteriod-containing cells were similar in the air and Ar: O2 treatments up to 16 d after sowing. Thereafter the Ar: O2 treatment caused cessation of growth and development of nodules, reduced protein levels in bacteroids and nodule plant cells, and progressive degeneration of nodule ultrastructure leading to premature senescence of these organs. Provision of NO 3 - (0.1–0.2 mM) to Ar: O2-grown seedlings overcame the abovementioned consequences of N2 deficiency on nodule and plant growth, but merely delayed the degenerative effects of Ar: O2 treatment on nodule structure and senescence. Treatment of Ar: O2-grown seedlings with NO 3 - greatly increased the protein level of nodules but the increase was largely restricted to the plant cell fraction as opposed to the bacteroids. By contrast, NO 3 - treatment of air-grown seedlings increased protein of bacteroid and host nodule fractions to the same relative extents when compared with air-grown plants not supplemented with NO 3 - . These findings, taken together with studies of the distribution of N in nodules of symbiotically effective plants grown from 15N-labeled seed, indicate that direct incorporation of fixation products by bacteroids may be a critical feature in the establishment and continued growth of an effective symbiosis in the cowpea seedling.
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  • 97
    ISSN: 1432-2048
    Keywords: Glutamine synthetase ; Leghaemoglobin ; Nitrogenase ; Nitrogen fixation ; Phaseolus ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activities of glutamine synthetase (GS), nitrogenase and leghaemoglobin were measured during nodule development in Phaseolus vulgaris infected with wild-type or two non-fixing (Fix-) mutants of Rhizobium phaseoli. The large increase in GS activity which was observed during nodulation with the wild-type rhizobial strain occurred concomitantly with the detection and increase in activity of nitrogenase and the amount of leghaemoglobin. Moreover, this increase in GS was found to be due entirely to the appearance of a novel form of the enzyme (GSn1) in the nodule. The activity of the form (GSn2) similar to the root enzyme (GSr) remained constant throughout the experiment. In nodules produced by infection with the two mutant strains of Rhizobium phaseoli (JL15 and JL19) only trace amounts of GSn1 and leghaemoglobin were detected.
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  • 98
    ISSN: 1432-1424
    Keywords: electron probe X-ray microanalysis ; Saccharomyces cerevisiae ; ethidium ; brontophenol blue ; cationic dye ; cytolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary K+ efflux provoked by ethidium proceeds partially as an all-or-none effect by which the diffusion barrier for K+ is disrupted and partially from still intact cells, presumably by exchange against ethidium. This is shown by the application of an electron probe microanalysis X-ray technique by which the K+ content of a number of individual cells is analyzed.
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  • 99
    ISSN: 1573-5036
    Keywords: Groundnut fertilization ; Nigeria ; Nitrogen fixation ; Nodulation ; Nutrient uptake ; Tropical soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It was observed in a long-term fertility study that P application results in better nodulation and seed yield. The N yield per plant increased significantly with P, K, and B application, but the promoting effect of K and B on N content per plant was not reflected in the final yield. Data on mean nutrient uptake indicate that about 63% of N, 68% of P, 23% of K, 4% of Ca and 24% of Mg were present in the kernels, the remainder being in the haulm and shells. Soil will be exhausted fast if the nutrient rich groundnut residues are completely exported from the field and not compensated by adequate fertilizer application. Judicious use of fertilizers on groundnut has been shown to yield more than 100 kg of biologically fixed N per hectare.
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  • 100
    ISSN: 1573-5036
    Keywords: Clover ; Fertilizer ; Lotus ; Nitrogen fertilizer ; Nitrogen fixation ; Nitrogen source ; Nodulation ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies under growth cabinet conditions investigated the effect of source and concentration of nitrogen and timing of nitrogen application on the growth and nitrogen fixation byLotus pedunculatus cv. Maku andTrifolium repens cv. S184. KNO3, NaNO3 and NH4NO3 were added at transplanting at the following rates: 3.33, 7.78 and 13.33 mg N/plant. KNO3 was added at 3.33 and 7.78 mg N/plant at 0, 6, 12, 18, 24 or 30 days after transplanting. Lotus shoot weight increased with all increasing nitrogen sources but clover only responded to KNO3 and NaNO3. The root weight of both species increased with increasing KNO3 and NH4NO3. The percentage increase in lotus and clover shoot growth was greater than that of root growth when KNO3 was added within a week of transplanting. Increases in growth by both species resulted from added nitrogen except with lotus when NaNO3 was applied where increased nitrogen fixation also contributed to increased growth. Weight and number of effective nodules on both species were increased with 3.33 mg N per plant as KNO3 but nitrogen fixation was not affected. Addition of 13.33 mg N as NaNO3 reduced weight and number of effective nodules in both species and also nitrogen fixation by lotus. KNO3 increased growth and nodulation of both species when applied within one week after transplanting. Nodulated lotus plants responded to KNO3 by increasing growth but not nodulation. KNO3 appeared to affect infection and development of nodules on lotus and may affect the growth of existing nodules on clover.
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