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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 42 (1986), S. 95-95 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 57 (1967), S. 68-75 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Im Zusammenhang mit dem Problem der Variabilität bei Essigsäurebakterien wurde die Wirkung einer Reihe von Antibiotica auf diese Organismen untersucht. Streptomycin, Novobiocin, Ampicillin, Tetracyclin und Chloramphenicol ergaben im Agar-Diffussionstest Hemmeffekte. Da Ampicillin und Novobiocin nur auf Zellen wirken, die in Teilung begriffen sind, eignen sie sich zur Anreicherung auxotropher Mutanten. Bei Chloramphenicol und Tetracyclin ist die Häufigkeit von spontanen resistenten Mutanten über einen gewissen Bereich unabhängig von der Antibioticum-Konzentration im Selektiv-Nährboden. Mit Hilfe von präparierten Filterpapierscheiben gelang es, nach dem von Newcombe verwendeten Prinzip Mutationsraten für Chloramphenicol- bzw. Tetracyclinresistenz zu bestimmen. Die Mutationsraten bewegen sich zwischen 1·10-5 und 1,9·10-7 und liegen somit im gleichen Größenbereich wie die Mutationsraten anderer Bakterien.
    Notes: Summary The action of some antibiotics on acetic acid bacteria has been tested. Streptomycin, Novobiocin, Ampicillin, Chloramphenicol and Tetracyclin inhibited growth in the agar-diffusion test. No growth-inhibition was observed with Penicillin G, Cephalosporin C, Polymyxin B, and Neomycin. Ampicillin and Novobiocin inhibited only growing cells and are of possible use for the enrichment of auxotrophic mutants. The frequency of spontaneous Chloramphenicol or Tetracyclin resistant mutants was, within a certain range, independent of the antibiotic concentration on the selective medium. Using a modification of Newcombe's method, the mutation rates for spontaneous Chloramphenicol- and Tetracyclin resistance was determined and was found to reach from 1·10-5 to 1,9·10-7.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 57 (1967), S. 76-92 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Mit einer modifizierten Penicillintechnik konnten aus Acetobacter-Populationen, die von einem prototrophen Klon stammten, spontane auxotrophe Mutanten isoliert werden. Bei sechs von acht untersuchten Stämmen wurden auxotrophe Mutanten gefunden. Die Häufigkeit dieser Mutanten betrug 10-6. Die Auxotrophie, welche je nach Stamm auf Äthanol- oder Glucose-Medium auftrat, äußerte sich als Bedarf für Hefeextrakt. Hefeextrakt konnte durch Alanin, Prolin oder Glutaminsäure nicht ersetzt werden. Die Mutation von prototroph auf Äthanol-Medium zu auxotroph auf Äthanol-Medium hatte keine Änderung der spezifischen Aktivitäten der Schlüsselenzyme des Glyoxylsäurecyclus zur Folge. Es wurden auch spontane Mutanten gefunden, welche die partikelgebundene Äthanoldehydrogenase verloren hatten und dadurch unfähig waren, Äthanol zu oxydieren oder als C-Quelle zu verwerten. Bei den spontanen, auf Äthanol-Medium auxotrophen Mutanten handelt es sich um Mutationen von einer Art des Frateurschen Systems in eine andere. Mutanten, welche die partikelgebundene Äthanoldehydrogenase verloren haben, gehören definitionsgemäß nicht mehr in die Gattung Acetobacter. Die Bedeutung solcher “interspezifischer” und “intergenerischer” Mutationen für die Arteinteilung innerhalb der Essigsäurebakterien wird diskutiert.
    Notes: Summary 8 prototrophic Acetobacter-strains were examined for spontaneous auxotrophic mutants. Using a modification of the Penicillin technique, there were detected auxotrophic mutants in 6 strains. The mutant frequency was 10-6. Auxotrophy manifested itself as a requirement for yeast extract. Alanine, proline and glutamic acid could not replace yeastextract. In addition to the auxotrophic mutants there were found spontaneous mutants, which had lost the particulate ethanol-dehydrogenase and therefore had become unable to oxidise ethanol. The mutation from prototrophic on minerals-ethanol medium to auxotropic on minerals-ethanol medium represents a mutation from one species of Frateur's system into an other species. Mutants which have lost the particulate ethanol-dehydrogenase belong no more to the genus Acetobacter. The importance of such interspecific and intergeneric mutations for the taxonomy of acetic acid bacteria is discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 5 (1972), S. 382-391 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der vorliegende II. Teil bezweckt, die wichtigsten Zusatzinformationen zu vermitteln, welche einen erfahrenen Benützer gepackter GC-Säulen in die Lage versetzen, Kapillarsäulen hoher Qualität über längere Zeit hinweg zu hoher Leistung zu bringen. Diese Informationen betreffen ausschließlich Glaskapillarsäulen, da sich deren Leistungen in mehrfacher Hinsicht weit über jene von Kapillaren aus Metall oder anderen Werkstoffen steigern lassen. Praktische Anleitungen zur Vorbereitung, zum Einbau in den Gas-Chromatographen, und zum Betrieb von Glaskapillarsäulen werden gegeben. Viel Raum wird der großen Zahl häufig auftretender und zum Teil einschneidender Störungen-welche bei gepackten Säulen meist belanglos sind-sowie ihrer Feststellung und Behebung gewidmet. Die Sammlung solcher, aus der Arbeit mit gepackten Säulen nicht direkt ableitbarer Erfahrungen soll zeigen, welche Randbedingungen zum analytischen Erfolg entscheidend beitragen. Sie soll damit der verbreiteten Tendenz entgegenwirken, bei einem Mißerfolg die Ursache zuerst bei der Kapillarsäule zu suchen.
    Abstract: Résumé Cette seconde partie de l'exposé est destinée à fournir des informations complémentaires parmi les plus importantes afin que l'utilisateur expert en CG sur colonnes remplies puisse obtenir un rendement optimal avec des colonnes capillaires de haute qualité pendant une période prolongée. Ces informations concernent exclusivement des colonnes capillairesen verre, puisque leur performance, à bien des égards, peut être rendue très supérieure à celle des colonnes capillaires en métal ou en d'autres matériaux. On donne des informations pratiques pour la préparation, l'installation dans le chromatographe en phase gazeuse et les manipulations sur des colonnes capillaires en verre. Dans une grande partie de l'exposé, on traite des perturbations fréquentes, et quelque fois sérieuses-qui sont souvent sans importance avec des colonnes remplies-, ainsi que de leur identification et leur élimination. La récapitulation d'ensemble de telles expériences, qui ne découlent pas directement du travail sur des colonnes remplies, doit montrer quelles sont les conditions qui contribuent d'une manière décisive au succès de l'analyse. Ceci doit combattre la tendance très répandue qui fait d'abord rechercher dans l'emploid d'une colonne capillaire l'origine d'un échec.
    Notes: Summary Part II is intended to provide the essential additional information to enable an experienced user of packed GC columns to achieve optimum performance of high-quality capillary columns over a long period of time. This information concernsglass capillary columns exclusively, since their performance, in several respects, can be made to exceed to a considerable degree that of capillaries made of metal or other materials. Practical instructions are given for the handling of glass capillary columns, for their installation into the gas chromatograph, and for their operation. Considerable space is devoted to the numerous faults that frequently occur some of which are serious-although usually negligible in packed columns- and to their detection and elimination. The account of such problems, experience with which cannot be gained directly from work with packed columns, is intended to show which marginal conditions contribute decisively to the success of an analysis. Thus it should disprove the widely held belief that any failure is primarily due to the capillary column.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 33 (1977), S. 1180-1181 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Squirrel monkeys learned to avoid hypoxia by pressing a bar. Each bar-press replaced the noxious gas mixture with normal air for 3 sec. The data further indicated that O2 itself has no positive reinforcing effect.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 51 (1989), S. 84-85 
    ISSN: 1420-9055
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 195 (1995), S. 67-76 
    ISSN: 1615-6110
    Keywords: Caryophyllaceae ; Dianthus glacialis ; Pollination ; nectar ; scent ; autogamy ; seed set ; seed/ovule ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollination of the alpine herbDianthus glacialis was studied in a population in the Swiss Alps in 1991 and 1992. Only one insect species,Zygaena exulans (Lepidoptera), was observed to visit the flowers ofD. glacialis. Pollen loads onZ. exulans indicate that it is an effective pollinator ofD. glacialis. In 1991,Z. exulans frequently visited flowers ofD. glacialis. However, in 1992 almost no visits could be observed. Despite the occurrence of pollinators and the conspicuous flowers ofD. glacialis, there are strong indications that this plant is mainly selfing: (1) anthesis of individual flowers is short (c. one and a half days), (2) protandry, although pronounced in otherDianthus spp., is absent, (3) nectar production is low, (4) odour production is weak, (5) seed production by spontaneous selfing is high, (6) seed set in emasculated flowers is extremely low and (7) the seed/ovule ratio is distinctly higher inD. glacialis than in outcrossing plants.—Selfing inD. glacialis could have evolved under a shortage of pollinators during the glaciation periods. Present levels of cross-pollination byZ. exulans have apparently not been sufficient to reverse the pollination mechanism ofD. glacialis from selfing to outcrossing.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 11 (1992), S. 543-546 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2015-12-07
    Print ISSN: 0944-1344
    Electronic ISSN: 1614-7499
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Springer
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  • 10
    Publication Date: 2015-01-20
    Description: Background: Bifidobacteria is one of the major gut commensal groups found in infants. Their colonization is commonly associated with beneficial effects to the host through mechanisms like niche occupation and nutrient competition against pathogenic bacteria. Iron is an essential element necessary for most microorganisms, including bifidobacteria and efficient competition for this micronutrient is linked to proliferation and persistence. For this research we hypothesized that bifidobacteria in the gut of iron deficient infants can efficiently sequester iron. The aim of the present study was to isolate bifidobacteria in fecal samples of iron deficient Kenyan infants and to characterize siderophore production and iron internalization capacity. Results: Fifty-six bifidobacterial strains were isolated by streaking twenty-eight stool samples from Kenyan infants, in enrichment media. To target strains with high iron sequestration mechanisms, a strong iron chelator 2,2-dipyridyl was supplemented to the agar media. Bifidobacterial isolates were first identified to species level by 16S rRNA sequencing, yielding B. bifidum (19 isolates), B. longum (15), B. breve (11), B. kashiwanohense (7), B. pseudolongum (3) and B. pseudocatenulatum (1). While most isolated bifidobacterial species are commonly encountered in the infantile gut, B. kashiwanohense was not frequently reported in infant feces. Thirty strains from culture collections and 56 isolates were characterized for their siderophore production, tested by the CAS assay. Siderophore activity ranged from 3 to 89% siderophore units, with 35 strains (41%) exhibiting high siderophore activity, and 31 (36%) and 20 (23%) showing intermediate or low activity. The amount of internalized iron of 60 bifidobacteria strains selected for their siderophore activity, was in a broad range from 8 to118 ?M Fe. Four strains, B. pseudolongum PV8-2, B. kashiwanohense PV20-2, B. bifidum PV28-2a and B. longum PV5-1 isolated from infant stool samples were selected for both high siderophore activity and iron internalization. Conclusions: A broad diversity of bifidobacteria were isolated in infant stools using iron limited conditions, with some strains exhibiting high iron sequestration properties. The ability of bifidobacteria to efficiently utilize iron sequestration mechanism such as siderophore production and iron internalization may confer an ecological advantage and be the basis for enhanced competition against enteropathogens.
    Electronic ISSN: 1471-2180
    Topics: Biology
    Published by BioMed Central
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