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  • 1
    ISSN: 0248-4900
    Keywords: Feulgen fluorescence ; Lowicryl embedding ; confocal laser scanning microscopy ; mammalian nucleolar chromatin ; mouse trophoblast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0309-1651
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A survey of novel microscopic approaches for structural and functional analysis of subnucleolar compartments will be presented. Research on nucleolar structure and function concentrates predominantly on two distinct types of nucleoli: (1) nucleoli present during the interphase of the cell cycle in somatic tissue culture cells and (2) nucleoli present in meiotic cells, e.g. oocytes of amphibians. These nucleoli are found during meiotic prophase of oogenesis and are functional during several months of the diplotene stage of oogenesis. A further characteristic is the fact that these nucleoli are extra-chromosomal, since they originate by selective ribosomal DNA (rDNA) amplification during the early pachytene stage of oogenesis. Miller-type chromatin spread preparations using transcriptionally active nucleoli, to a major part, contributed to our understanding of the structural organization of polymerase I directed pre-rRNA transcription. Although the structural organization of the template-associated pre-rRNA transcript is known in some detail from chromatin spreads, relatively little is known about structural aspects of pre-rRNA processing. In order to investigate this intriguing question in more detail, we have developed a computer-based densitometry analysis of both template-associated and template-dissociated pre-rRNA transcripts in order to follow the structural modification of pre-rRNA transcripts during processing. Another line of experiments is devoted to the in situ structure of actively transcribing genes in the nucleolus. In order to bridge the gap between light microscopy and electron microscopy we started video-enhanced light microscopical analysis of actively transcribing genes. Although the dimensions of individual spread genes are critical for detection by optical microscopy, we succeeded in obtaining the first series of images of transcribing genes in their ’native’ hydrated state. An additional promising type of microscopy is transmission X-ray microscopy. Recent progress in instrumentation as well as in sample preparation has allowed us to obtain the first images of density distribution within intact, fully hydrated nucleoli using amplitude-contrast and/or phase-contrast X-ray microscopy of non-contrasted, fully hydrated nucleoli at different states of transcriptional activity. Whereas the above mentioned investigations using video microscopy and X-ray microscopy are predominantly applicable to the analysis of amplified nucleoli in amphibian oocytes, which are characterized by an extremely high transcription rate of 80–90% of rDNA genes per individual nucleolus, structural analysis of the in situ arrangement of actively transcribing genes in somatic nucleoli as present in the interphase nucleus is far more difficult to perform, mainly due to the much lower number of simultaneously transcribed active genes per individual nucleolus. Visualization of actively transcribed gene clusters is approached by an integrated experimental assay using video microscopy, confocal laser scan microscopy, and antibodies against specific nucleolar proteins.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Der Orthopäde 26 (1997), S. 981-986 
    ISSN: 1433-0431
    Keywords: Key words Stretching • Muscular imbalance • Muscle length testing • Muscle stretching techniques ; Schlüsselwörter Stretching • Muskuläre Dysbalance • Längentestung der Muskulatur • Muskeldehntechniken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Stretching als statische Dehntechnik fand in den letzten 15 Jahren im Fitness- und Sportbereich eine weite Verbreitung. In der Krankengymnastik und manuellen Therapie hatte sich diese Dehntechnik bereits lange als wirksame therapeutische Maßnahme bewährt. Beim Vorliegen einer muskulären Dysbalance mit dadurch bedingten funktionellen Störungen am muskuloskelettalen System wurde das statische Dehnen zusammen mit Kräftigungsgymnastik zur Therapie der Wahl. Die Längentestung der Muskulatur ist dabei die klinische Untersuchung zur Erfassung von Muskelverkürzungen. Die Grundlagen dazu werden beschrieben. Die verschiedenen Formen der Muskeldehntechniken werden dargestellt: dynamisches Dehnen (Schwunggymnastik), statisches Dehnen (Stretching), unterteilt in passive statische Dehnübungen und die neuromuskulären Dehnübungen. Die neurophysiologischen Hintergründe werden diskutiert, ebenso der Stellenwert der einzelnen Methoden in der funktionellen Gymnastik. Praktische Beispiele für die wichtigsten Muskelgruppen sind dargestellt.
    Notes: Summary Static stretching exercises have become very popular over the past fifteen years both in professional and amateur sports. In the fields of physical therapy and in manual therapy, in particular, static stretching has become part of a standard and successful treatment modality. Together with an appropriate strengthening program, static stretching techniques have become the therapy of choice for treatment of muscle imbalances associated with functional disturbances of the musculoskeletal system. Specific muscle length testing procedures have been developed to determine muscle shortening in clinical practice. In this article, the fundamental principles of the different types of muscle stretching techniques are described, including the dynamic stretching and static stretching techniques. The exercises are organized along the concepts of passive static or neuromuscular stretching principles. The pertaining neurophysiologic fundamentals are discussed, as are the benefits of the individual methods of a functional exercise program. Examples are provided for the most important muscle groups.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 147 (1982), S. 207-210 
    ISSN: 0014-5793
    Keywords: Cytochemistry ; Ehrlich cell ; Glycogen ; Glycogen synthase ; Nucleus
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Es wird eine verbesserte Methode beschrieben, mit der innerhalb einer Sammelperiode von 3 min etwa 50-100 frisch besamte Eier vonDrosophila melanogaster gewonnen werden können. Verglichen mit den bisher üblichen Sammelperioden von 10, 30 oder mehr min erhält man wesentlich stadienhomogenere Gelege. Eine weitere Verkürzung der Sammelperiode unter 3 min ist wegen der stark abnehmenden Anzahl Eier je Gelege nicht möglich. Vorausgesetzt, dass alle Störungen der Fliegen durch Erschütterungen, Licht, Temperaturschwankungen usw ausgeschaltet werden, können z.B. für strahlenbiologische Experimente zahlreiche 3-min-Gelege im Laufe von 6 oder mehr Stunden gewonnen werden.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the growing and maturing primary nucleus ofAcetabularia mediterranea andAcetabularia major has been studied with the use of various fixation procedures. Particular interest has been focused on the details of the nuclear periphery and the perinuclear region. It is demonstrated that early in nuclear growth a characteristic perinuclear structural complex is formed which is, among the eukaryotic cells, unique toAcetabularia and related genera. This perinuclear system consists essentially of a) the nuclear envelope with a very high pore frequency and various pore complex associations with granular and/or threadlike structures some of which are continuous with the nucleolus; b) an approximately 100 nm thick intermediate zone densely filled with a filamentous material and occasional small membraneous structures from which the typical cytoplasmic and nuclear organelles and particles are excluded; c) an adjacent lacunar labyrinthum which is interrupted by many plasmatic junction channels between the intermediate zone and the free cytoplasm; d) numerous dense perinuclear bodies in the juxtanuclear cytoplasm which are especially frequent at the junction channels and reveal a composition of aggregated fibrillar and granular structures; e) very dense exclusively fibrillar aggregates which occur either in association with the perinuclear region of the lacunar labyrinthum or, somewhat further out, in the cytoplasmic strands between the branches of the lacunar labyrinthum in the form of slender, characteristic rods or “sausages”. A variety of other membraneous and non-membraneous structures characteristic of the juxtanuclear cytoplasm is described. The organization of the individual components in this special complex is summarized in a model drawing. The dynamic and transitory nature of this perinuclear complex apparatus is emphasized and its possible role in nuclear functions and in regulating nucleocytoplasmic interactions is discussed.
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  • 10
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An electron microscopic survey of nuclear events and changes in the perinuclear cytoplasm during the generative phase ofAcetabularia is presented with details on late stages in the maturation of the primary nucleus, possible modes of formation of secondary nuclei, the mitosis of secondary nuclei, migration of secondary nuclei into the stalk and the cap, the fine structure of nuclei and perinuclear cytoplasm during cyst formation and gametogenesis as well as during gamete fusion and zygote formation.
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