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  • Biology
  • GENERAL
  • General Chemistry
  • Life and Medical Sciences
  • 1975-1979  (94)
  • 1955-1959  (23)
  • 1978  (44)
  • 1976  (50)
  • 1958  (23)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 149 (1976), S. 459-482 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The salivary gland of adult Calliphora erythrocephala is a tubular structure composed of secretory, reabsorptive, and duct regions. Development of these structures has been followed during the six days of larval and ten days of pupal growth. Two small groups of imaginal cells located at the junction between larval gland and duct give rise to the adult gland. These presumptive adult cells divide during all larval stages and appear to be functional components of the larval gland. Shortly after pupation, the larval gland breaks down and the imaginal cells proliferate rapidly, forming sequentially the duct, reabsorptive and secretory regions. Proliferating regions of the developing gland are frequently encrusted with haemocytes. As it elongates the gland establishes intimate contacts first with the basement membrane of the degenerating larval gland, later with an epithelial layer surrounding the main dorsal tracheal trunks, and then with the gut. Cell division continues until about five days after pupation, bu t the gland is unable to secrete fluid in response to 5-hydroxytryptamine stimulation until two hours after the adult fly emerges. The Golgi complex appears to be involved in forming the highly folded membranes of the canaliculi in the secretory region.Presumptive adult salivary gland cells appear to increase in number logarithmically from the time of hatching of the larva until five days after pupation. This contrasts with the development of classical imaginal discs, in which cell division ceases prior to pupation.
    Additional Material: 35 Ill.
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Alveolar macrophages harvested by bronchopulmonary lavage from rats exposed to tobacco smoke for 30 days (“smokers”) showed alterations in oxidative metabolism, lactate production and phagocytosis of inert starch particles when compared with control macrophages. Phagocytosis of viable Staphylococcus aureus was unaffected by tobacco smoke. Glucose oxidation measured by conversion of glucose-1-14C to 14CO2 was moderately affected while oxidation of glucose-6-14C to 14CO2 was not. Smokers routinely yielded fewer cells than controls, though these cells contained approximately 17% more protein than did controls. Opsonization of particles was not necessary for macrophages from either smoker or control animals to manifest a respiratory burst and increased superoxide and hydrogen peroxide release during phagocytosis. The glycolytic inhibitors, sodium fluoride and iodoacetamide, while effectively blocking glycolysis, did not inhibit phagocytosis by macrophages from either group. The results reported clearly distinguish alveolar macrophages from other phagocytic cells (peritoneal macrophages and polymorphonuclear leukocytes) and suggest a state of non-specific activation caused by exposure to tobacco smoke.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 95 (1978), S. 275-285 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between plasminogen activator levels and the expression of the transformed phenotype was studied in a 5-bromodeoxyuridine (BrdUrd) dependent mutant of Syrian hamster melanoma cells. In terms of cell morphology and cellular interactions, the BrdUrd dependent cells resemble transformed cells when grown in the presence of BrdUrd but resemble untransformed cells when grown in the absence of BrdUrd. It was found that the BrdUrd dependent cells release significant levels of plasminogen activator only when cultured in the absence of BrdUrd. In the presence of BrdUrd, the release of plasminogen activator by the dependent cells is suppressed, and the decreased level of plasminogen activator released in the presence of BrdUrd seems to be due to decreased production of active enzyme. Growth tests revealed that the BrdUrd dependent cells, when attached to a substrate, required BrdUrd in order to attain high densities. Furthermore, the cells are able to grow well in soft agar only in the presence of BrdUrd. These results suggest that the production and release of high levels of plasminogen activator are not related (either as cause or effect) to the expression of the transformed phenotype in the BrdUrd dependent cellsThe effect of dog serum (as a plasminogen source) on the BrdUrd dependent cells also was tested. It was found that cells cultured in medium containing dog serum exhibit a morphological alteration, but only in the absence of BrdUrd. The morphological response of the cells to dog serum resembles that previously observed with virus-transformed cells. In the BrdUrd dependent cells, the morphological response to dog serum appears correlated with the release of plasminogen activator but separated from other transformed characteristics.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The DNA content of individual sperm from populations of acriflavine-stained cells was investigated by analysis of fluorescence frequency distributions obtained with high-resolution flow-systems instruments. Sperm with spherical or cylindrical heads from three mollusk species produce narrow, symmetric fluorescence distributions. Flat sperm heads from six eutherian species produce asymmetric distributions consisting of a peak with a lateral extension to higher fluorescence values. The unexpected shape of these distributions was shown to be due to the flat geometry and high refractive index of the sperm heads in conjunction with the orthogonal axes of flow, excitation, and detection in the flow-systems instruments. The theoretical and experimental results indicate that the lateral extension can be eliminated either by controlling the sperm orientation with planar flow conditions or by accounting for sperm orientation by means of orientation sensing.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 1 (1978), S. 13-18 
    ISSN: 0148-7280
    Keywords: immunoperoxidase localization ; fertilization ; Xenopus laevis ; cortical reaction ; block to polyspermy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: At fertilization, the vitelline envelope surrounding the egg of Xenopus laevis is modified by the addition of an electron-dense component termed the “F layer.” The F layer functions as a block to polyspermy and as a block to the escape of macromolecules from the perivitelline space, thereby causing an osmotically driven envelope elevation. F-layer formation has been hypothesized to result from interaction between a cortical-granule lectin, released in the cortical reaction, and a jelly-coat ligand. Evidence for this hypothesis was sought by determining the location of the cortical-granule lectin both before and after fertilization, using a specific antibody conjugated to horseradish peroxidase. The cortical-granule lectin was localized only in the cortical granules of the unfertilized egg and was located predominantly in the perivitelline space and the F layer of a fertilized egg. These observations support the hypothesis that the F layer is formed by a cortical-granule-Iectin-jelly layer-ligand interaction.
    Additional Material: 4 Ill.
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  • 6
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 7
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 102 (1958), S. 91-117 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pineal-paraphyseal complex of sea turtles is an impressively large structure which projects dorsally and anteriorly above the prosencephalon. The complex was examined by light microscopy in several age classes of green sea turtles (Chelonia mydas) and from juvenile loggerhead turtles (Caretta caretta). The paraphysis is extensively fused to the distal portion of the pineal body, suggesting an interrelated function for these two tissues. No duct or canal was observed connecting the pineal lumen to the third ventricle. Two pineal cell types are described which appear to correspond to the neuroglial supportive cells and the secretory rudimentary photoreceptor cells of other amniotic vertebrates. A possible luminal secretion in the form of apical protrusions is produced by the latter cell type. No typical photoreceptive outer segments were observed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 158 (1978), S. 21-29 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tibiotarsal segments of 12-day chick embryos homozygous for the crooked neck dwarf gene (cn/cn) were examined histologically following routine methods of preparation. The myogenic mass fails to divide into separate muscle bundles during the early stages of differentiation. Myoblasts and myotubes are observed, although the proportion favors the mononucleate cell population. Multinucleate myotubes are often wavy in appearance and many contain eosinophilic cytoplasmic inclusions. The entire tissue mass of mutants appears more compacted than in control limbs. Poor organization of muscle appears related to the lack of a suitable connective tissue system. Epimysia, perimysia, and subcutaneous connective tissue fail to develop properly. Tendons are poorly developed or absent. Comparisons between mutant and control embryos show no differences in peripheral innervation. Nerve fascicles penetrate deeply into the developing muscle of both species. The distribution of vascular elements is seemingly normal also. Skeletal muscle of cn/cn embryos is capable of differentiating to the myotube stage, after which it undergoes cellular degeneration without achieving a functional state. Comparisons of this mutant with alleged chemical phenocopies show important differences.
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