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  • Electron microscopy  (183)
  • Development  (15)
  • Springer  (196)
  • 2015-2019
  • 1975-1979  (98)
  • 1970-1974  (98)
  • 1975  (98)
  • 1972  (98)
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  • Springer  (196)
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  • 2015-2019
  • 1975-1979  (98)
  • 1970-1974  (98)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 8 (1975), S. 319-331 
    ISSN: 1432-0630
    Keywords: Self-interstitials in silicon ; Swirls ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Point defect agglomerates in dislocation-free silicon crystals, usually called “swirls”, have been investigated by means of high-voltage electron microscopy. It was found that a single swirl defect consists of a dislocation loop or a cluster of dislocation loops. By contrast experiments it could be shown that these loops are formed by agglomeration of self-interstitial atoms. Generally the loops have a/2〈110〉 Burgers vectors, but in specimens with high concentrations of carbon (∼1017 cm−3) and oxygen (∼1016 cm−3) also dislocation loops including a stacking fault were observed. In crystals grown at growth rates higher thanv=4 mm/min no swirls are observed; lower growth rates do not markedly affect the size and shape of the dislocation loops. With decreasing impurity content (particulary of oxygen and carbon) the swirl density decreases, whereas the dislocation loop clusters become larger and more complex. A model is presented which describes the formation of swirls in terms of agglomeration of silicon self-interstitials and impurity atoms.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 9 (1972), S. 122-130 
    ISSN: 1432-0827
    Keywords: Tetracycline ; Development ; Calcification ; Statolith ; Nematocysts ; Aurelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'effet de la tétracycline HCl sur la synthèse de statolithes de sulfate de calcium chezAurelia a été étudié. La tétracycline inhibe la synthèse de statolithes et nématocystes à un stade précoce de strobilation. La tétracycline, cependant, n'est pas incorporée dans les statolithes ou nématocystes en formation. Comme la tétracycline ne se combine pas avec le calcium des statolithes de sulfate de calcium dihydraté d'Aurelia, l'explication des effets d'inhibition sur la différenciation de statolithes et nématocystes ne semble pas liée avec un facteur en rapport avec l'incorporation. Des étudesin vitro de quatre systèmes inorganiques de calcium et de tétracycline montrent que le sulfate de calcium dihydraté (gypse) n'incorpore pas la tétracycline: il en est de même de son équivalent isostructural, le phosphate de calcium hydrogéné dihydraté (brushite). Le carbonate de calcium et le phosphate de calcium (apatite) incorpore la tétracycline. L'explication des différences de comportement du calcium peut être liée à la structure cristalline des composés respectifs, et, en particulier, au fait que l'ion Ca est prêt ou non à réagir avec la tétracycline.
    Abstract: Zusammenfassung Es wird über die Wirkung von Tetracyclinchlorhydrat auf die Synthese von Calciumsulfat-Statolithen beiAurelia berichtet. Wird das Tetracyclin in einem Frühstadium der Strobilation verabreicht, so hemmt es die Synthese der Statolithen und der Nematocysten. Das Tetracyclin wird jedoch nicht in die sich bildenden Statolithen oder Nematocysten eingebaut. Da sich das Tetracyclin nicht mit dem Calcium der Calciumsulfatdihydrat-Statolithen derAurelia verbindet, so kann dessen Hemmwirkung auf die Statolithen und die sich differenzierenden Nematocysten offenbar nicht mit einem einbaubedingten Faktor erklärt werden. Untersuchunge, die in vitro mit vier verschiedenen anorganischen Calciumsalzen und Tetracyclin ausgeführt wurden, zeigten, daß weder Calciumsulfatdihydrat (Gips), noch dessen isotrukturelles Aequivalent Calciumhydrogenphosphatdihydrat (Bruschit) Tetracyclin einbauen. Dagegen inkorporieren Calciumcarbonat und Calciumphosphat (Apatit) das Tetracyclin. Die Erklärung für dieses unterschiedliche Verhalten der Calciumsalze findet sich in der Kristallstruktur der betreffenden Verbindungen, d.h. es hängt davon ab, ob das Calciumion ür die Reaktion mit Tetracyclin leicht verfügbar ist.
    Notes: Abstract The effect of tetracycline HCl on synthesis of calcium sulphate statoliths inAurelia is reported. Tetracycline inhibits synthesis of statoliths and nematocysts when administered at an early stage of strobilation. The tetracycline, however, is not incorporated into the developing statoliths or nematocysts. As the tetracycline does not combine with the calcium of the calcium sulfate dihydrate statoliths ofAurelia, an explanation for its inhibitory effects on statoliths and nematocyst differentiation apparently does not rest with an incorporation-related factor. In vitro studies of four inorganic calcium systems and tetracycline revealed that calcium sulfate dihydrate (gypsum) did not incorporate tetracycline nor did its isostructural equivalent, calcium hydrogen phosphate dihydrate (brushite). Calcium carbonate and calcium phosphate (apatite) did incorporate tetracycline. The explanation for these different behaviors of calcium can be found in the crystal structure of the respective compounds, namely, whether or not the Ca ion is readily available to react with tetracycline.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 9 (1972), S. 173-178 
    ISSN: 1432-0827
    Keywords: Phosphatase ; Development ; Bone ; Growth ; Rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une étude longitudinale, par séries, est effectuée pour déterminer les activités en phosphatases acide et alcaline dans les os longs et la mandibule. Le pH optimum des deux enzymes se situe respectivement à 10.2 et 5.4 pour les phosphatases alcaline et acide. Des portées synchronisées de rats sont sacrifiées, à raison d'une portée par jour, en commençant au premier jour jusqu'au 25ème jour post-partum. Les spécimens sont analysés en ce qui concerne leur concentration en protéine et leur activité en phosphatases. Une activité de types élevée et faible est observée au niveau du tissu osseux, ainsi qu'un type d'activité faible en phosphatase alcaline, au cours des pics d'activité en phosphatase acide, et vice-versa. Les pics observés suggèrent une concordance entre l'activité en phosphatase et les autres changements biochimiques de la croissance osseuse, au niveau de la matrice organique et la formation minérale. Une étude séparée, tenant compte de la possibilité d'une activité enzymatique rythmique, suggère l'existence d'un rythme diurne court chez les animaux jeunes.
    Abstract: Zusammenfassung Eine serienmäßige Longitudinaluntersuchung wurde unternommen, um die Aktivitäten der alkalischen und sauren Phosphatase in den Röhrenknochen und den Mandibulae von Ratten zu bestimmen. Das pH-Optimum der beiden Enzyme wurde für die alkalische Phosphatase bei 10,2 und für die saure Phosphatase bei 5,4 ermittelt. Synchronisierte und randomisierte Würfe wurden getötet, 1 Wurf pro Tag vom 1.–25. Tag post partum. Die Proben wurden auf ihren Proteingehalt und ihre Phosphatasenaktivität untersucht. Ein Muster niedriger und hoher Aktivität konnte in beiden Knochengeweben beobachtet werden, sowie ein Muster von niedriger Aktivität der alkalischen Phosphatase bei Spitzenwerten der sauren Phosphatase und umgekehrt. Die beobachteten Spitzenwerte lassen einen Zusammenhang vermuten zwischen der Phosphatasenaktivität und den anderen biochemischen Veränderungen, die im wachsenden Knochen auftreten, d. h. Bildung der organischen Matrix und des Minerals. Eine getrennte Untersuchung, welche sich mit der Möglichkeit rhythmischer Merkmale der Enzymaktivität befaßte, läßt vermuten, daß in den ersten Tagen ein schwacher Tagersrhythmus bestehen könnte.
    Notes: Abstract A serial longitudinal study was undertaken to determine the activities of the alkaline and acid phosphatases in the long bones and mandibles. The optimum pH of the two enzymes was recorded at 10.2 and 5.4 for alkaline and acid phosphatase, respectively. Synchronized and randomized litters of rats were killed, 1 litter daily, starting at day 1 to day 25 post partum. Samples were analyzed for protein concentration and activity of the phosphatases. A pattern of low and high activity was observed in both bony tissues, as well as a pattern of low alkaline phosphatase activity during acid phosphatase activity peaks, and vice versa. The observed peaks suggest a correspondence between phosphatase activity and the other biochemical changes occurring in the growing bone, i.e., organic matrix and mineral formation. A separate study, considering the possibility of rhythmic features of the enzyme activity suggests that there may be a small diurnal rhythm at an early age.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 103 (1975), S. 231-236 
    ISSN: 1432-072X
    Keywords: Chamaesiphonosira cymbellicola ; Budding Bacteria ; Development ; Epiphytism ; Cyanophycaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Chamaesiphonosira cymbellicola n. gen., n. sp., entwickelt lang-kegelige, farblose Zellen, die mit der breiteren Basis festsitzen und an der Spitze bis zu 30 eine später zerfallende Kette bildende Knospenzellen abschnüren. Es ergibt sich daraus eine äußerliche ähnlichkeit mit der Cyanophycee Chamaesiphon, doch besteht keine cytologische Übereinstimmung. Die Art kommt ausschließlich auf lebenden Zellen der Diatomee Cymbella cesati vor, trotz reichlichem Angebot vieler anderer ähnlicher Diatomeen und anderer Algen; es handelt sich also um einen sehr spezialisierten Epiphytismus. Außerdem werden bestimmte Stellen der “Wirts” pflanze bevorzugt. Eine Schädigung tritt nicht ein; es erfolgt Übertragung auf die Epitheken der Tochterzellen. Systematisch läßt sich die Gattung am besten in den Caulobacterales sensu Henrici u. Johnson (1935) unterbringen. Als zweite Art ist offenbar Chamaesiphon hyalinus Scherffel (1907) zu ihr zu stellen.
    Notes: Abstract The organism shows long-conical, colourless cells of bacterial size, affixed with the broader basis and cutting off buds from the free apex in numbers as high as 30, which form a chain and later separate. Multiplication is entirely by budding. Some resemblance to Cyanophycean cells, in particular to the exosporangia of Chamaesiphon, seems to be cytologically not verified. The organism grows exclusively on living cells of the diatom Cymbella cesati, and is fixed to them principally on the edges of the valvae. In spite of the presence of many other similar diatom species, the organism represents a remarkable case of extremely specialized epiphytism. There are no signs of damage of the “host” cell, in cell division the epiphyte is taken over by the epithecae of the daughter cells. Systematically the species because of practical reasons can be included into the Caulobacterales sensu Henrici and Johnson (1935). A second species, obviously belonging in here, is represented by Chamaesiphon hyalinus Scherffel (1907).
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  • 5
    Electronic Resource
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    Springer
    Archives of microbiology 106 (1975), S. 195-200 
    ISSN: 1432-072X
    Keywords: Trichophyton terrestre ; Trichophyton rubrum ; Hyphal fusions ; Origin of intra-hyphal hyphae ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cell observation chamber was designed to perform continuous photomicroscopic observations of hyphal anastomosis and the origin of intra-hyphal hyphae in Trichophyton terrestre and T. rubrum. These data were correlated with ultrastructural features of intra-hyphal hyphae. Hyphal fusions occurred commonly in either species of Trichophyton when incubated alone. In T. terrestre, empty hyphal segments adjoined by live units were invaded at the septa from both directions by new hyphal ingrowth. Continuous observations revealed that the intra-hyphal hyphae subsequently anastomosed via a lateral fusion peg. Similar intra-hyphal hyphae were shown in T. rubrum. Electron microscopic studies revealed ascomycetous septa in both conventional hyphae and intra-hyphal hyphae. For the latter, the cytoplasm and wall of the inner hypha were bounded by cytoplasmic organelles and another cell wall of the outer hypha.
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  • 6
    Electronic Resource
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    Springer
    Archives of microbiology 104 (1975), S. 285-288 
    ISSN: 1432-072X
    Keywords: Vibrio alginolyticus ; Flagella ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of peritrichous flagella and, consequently, swarming of Vibrio alginolyticus depend on a complex relationship between temperature, salt concentrations and pH. At temperatures above 28°C V. alginolyticus did not develop peritrichous flagella unless certain minimal concentrations of NaCl are present: the higher the temperature, the higher the NaCl concentrations required for peritrichous flagella synthesis. This requirement for NaCl at high temperatures is much more pronounced at pH 9 than at pH 6. High temperatures and low concentrations of NaCl also inhibited swarming of cells already armed with peritrichous flagella. Other cations, such as Li+, K+ and Mg2+, replaced NaCl only at temperatures below 28°C.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 105 (1975), S. 193-199 
    ISSN: 1432-072X
    Keywords: Bean ; Rust ; Haustorium ; Sheath ; Autoradiography ; Infection ; Electron microscopy ; Phaseolus vulgaris ; Uromyces phaseoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tritium labeled uredospores of Uromyces phaseoli were produced be feeding the host, Phaseolus vulgaris, with 3H-orotic acid. These spores were allowed to germinate on and to penetrate into a bean leaf. 24 hrs after inoculation, the bean rust had formed the first haustorium. All fungal structures, including the fungus walls, were heavily labeled. No label could be detected in the cells that had come into contact with the hyphae. In the infected host cell, the haustorium was labeled heavily, but the sheath around the haustorium and the host cell remained free of label. These results indicate that no detectable amounts of label leach from the bean rust into the host at this stage of infection although it is known that the rust takes up many metabolites. Since the sheath remains free of label and all fungal structures are evenly labeled, it is concluded that the sheath is formed by the host.
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  • 8
    Electronic Resource
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    Springer
    Cell & tissue research 123 (1972), S. 47-54 
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Neurohypophysis ; Exocytosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Elektronenmikroskopische Untersuchungen an der Neurohypophyse von Ratte und Forelle ergeben, daß sich eine Exocytose von Elementargranula an den Endigungen der neurosekretorischen Fasern nur selten abspielt. Es wird daher angenommen, daß die Abgabe von Hormonen in der Neurohypophyse in der Regel nach dem Muster des „membrane-release“ abläuft. 2. Die Exocytose wird nicht durch eine unmittelbare tangentiale Fusion der Membran des Elementargranulums mit dem Plasmalemm der Nervenendigung (Axolemm) eingeleitet. Vor allem bei Anwendung eines Goniometertisches wird erkennbar, daß vor der Exocytose zwischen Axolemm und Membran des Granulums eine Verbindung in Gestalt eines Stieles entsteht. Die Länge dieses Verbindungsstückes entspricht etwa 2 Axolemmdicken. An der Basis des Stiels im Axolemm tritt das Stoma auf, durch das der Inhalt des Granulums bzw. dieses selbst das Axonende verläßt. 3. Die Herkunft kleiner membrannaher Vesikel (Durchmesser 500 Å) in den Endigungen neurosekretorischer Nervenfasern in der Neurohypophyse konnte nicht geklärt werden. Anzeichen einer kompensatorischen Endocytose im Sinne von Nagasawa, Douglas und Schulz (1970) wurden nicht beobachtet.
    Notes: Summary 1. Electron microscopical investigations of the neurohypophysis in rat and trout reveal that exocytosis of neurosecretory elementary granules from the nerve endings occurs only rarely. The authors are of the opinion that hormone release in the neural lobe follows mainly the “membrane-release” pattern. 2. Exocytosis is not performed by tangential fusion of the elementary granule membrane and the plasmalemma of the nerve ending (axolemma). Administering the goniometer technique one can observe the appearance of a stalk-like structure connecting the two membranes. The basis of the stalk in the axolemma corresponds to the site of the stoma through which the core of the vesicle leaves the nerve ending. 3. The mechanism of the origin of small clear vesicles (diameter 500 Å approx.) near the axolemma of the neurosecretory terminal has not been elucidated. The authors did not observe equivalents of a compensatory endocytosis in the vicinity of granules released by exocytosis.
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  • 9
    ISSN: 1432-0878
    Keywords: Neurones ; Lumbricus ; Monoamines ; Neurosecretion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cerebral ganglion and the ventral nerve cord of Lumbricus terrestris have been studied with the electron microscope. The results are as follows: In the neuropile small granular vesicles (300 to 500 Å) occur in some varicose nerve fibres after fixation with potassium permanganate. This indicates the presence of noradrenaline. Sometimes only a few of the vesicles produce a positive reaction. After incubation with α-methyl-noradrenaline the numbers of nerve terminals with small granular vesicles greatly increase, indicating the presence of dopamine and/or 5-hydroxytryptamine. In this case the reaction is now complete. The number of small granular vesicles is largest in the terminal swellings. These findings are consistent with histofluorescence, chemical, and microspectrofluorometric analyses, which have demonstrated noradrenaline, dopamine, and 5-hydroxytryptamine in neurones in the central nervous system. Large granular vesicles (600 to 900 Å) are to be found in some perikarya, not identical with neurosecretory cell bodies. In this case the granular vesicles in the axon are smaller and fewer. This indicates a simultaneous proximo-distal transport and gradual decrease in size of the granular vesicles. The intraneuronal distribution of the vesicles is in agreement with the distribution of the fluorophores in the fluorescent neurones. Neurosecretory neurones are found most likely not to contain monoamines.
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  • 10
    Electronic Resource
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    Cell & tissue research 126 (1972), S. 431-436 
    ISSN: 1432-0878
    Keywords: Golgi apparatus ; Granular endoplasmic reticulum ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Numerous morphological continuities between the cisternae of the convex face of the Golgi apparatus and the granular endoplasmic reticulum (GER) were observed in post-division amebae that had divided following enucleation and renucleation. Electron microscopic radioautography with the use of 3H-uridine as a tracer indicated that perhaps the Golgi apparatus is derived from the GER. The possibility of the connections between GER and Golgi apparatus facilitating transport of materials between the two is also discussed.
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