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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for the priming role of the central retinula cell in ommatidium differentiation of Ephestia kuehniella (1988)
    Springer
    Development genes and evolution 197 (1988), S. 184-189 
    Details
    ISSN: 1432-041X
    Keywords: Ommatidia differentiation ; Eye imaginal disc ; Insect eye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the developing compound eye of Ephestia kuehniella, within the advancing front of differentiation, regular cell clusters arise which consist of a central cell and two flanking cells. The central cell is destined to become the basal retinula cell later in development. Its crucial role in ommatidium formation is confirmed by 3H-thymidine labelling. Eye anlagen labelled early in the pupal stage incorporate thymidine within two distinct zones along the front of differentiation. After the ommatidia are completely differentiated, both zones contain labelled nuclei of all cell types which participate in ommatidia formation. Within the posterior zone, however, the basal retinula cells are always unlabelled, whereas in the anterior they show labelled nuclei. From this observation it must be concluded that the basal retinula cell first terminates proliferation (either alone or together with a few other cells) to become differentiated as the central retinula cell. These results agree with those found in Drosophila and indicate that the ordered stepwise addition of cells to a central founder cell is a widespread principle of ommatidia formation in insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427922
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of lung preservation solutions on PMN activation in vitro (1999)
    Springer
    Transplant international 12 (1999), S. 113-121 
    Details
    ISSN: 1432-2277
    Keywords: Key words Lung preservation solution ; neutrophil ; chemotaxis ; adhesion molecule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Polymorphonuclear leukocyte (PMN) activation and PMN-endothelial cell interactions may cause graft failure due to ischemia-reperfusion injury after lung transplantation. We investigated the effects of Euro-Collins solution (EC), low-potassium dextran solution (LPD), and EC plus pentoxifylline (EC-PTXF) on adhesion molecule (CD11b/CD18 and L-selectin) expression, chemotaxis, and oxidative burst of PMN. PMN from healthy human volunteers were incubated with EC, LPD, and EC-PTXF, and, in controls, without preservation solution. LPD exerted a suppressive effect on PMN chemotaxis as compared to EC (P 〈 0.05), but had no attenuating effect on the increase of CD11b/CD18, the shedding of L-selectin, and intracellular oxidant generation. EC-PTXF attenuated the expression of CD11b/CD18 and the oxidative burst as compared to EC alone (P 〈 0.05). These effects of LPD and PTXF on PMN function may contribute to successful organ preservation in transplantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001470050195
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of the cytoskeleton in Amoeba proteus (1983)
    Springer
    Cell & tissue research 232 (1983), S. 79-96 
    Details
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; IAF-actin ; Microinjection ; Motive force generation ; Amoeba proteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fluorescein-labeled muscle actin was microinjected into Amoeba proteus and followed during intracellular redistribution by means of the image-intensification technique. The fully polymerizationcompetent protein becomes part of the endogenous actomyosin system undergoing dynamic changes over time periods of several hours. Singleframe analysis of long-term sequences enabled the direct demonstration of both the contractile activities and morphological transformations of microfilaments in normally locomoting, immobilized and phagocytozing specimens. In normally locomoting cells the filament layer undergoes continuous changes in spatial distribution depending on the actual pattern of cytoplasmic streaming and cell shape. The highest degree of differentiation is always maintained in the intermediate region between the front and the uroid, thus indicating this segment of the cortex to be the most important site in generating motive force for pseudopodium formation and ameboid movement. In immobilized cells contracted by the application of ruthenium red or relaxed by different anesthetics, the filament layer forms a continuous thick sheath beneath the cell surface or becomes completely disintegrated. In phagocytozing cells the local polymerization of actin at the tip of pseudopodia forming the food-cup and around the nascent phagosome points to a significant participation of the actomyosin system in the process of capturing and constricting prey organisms. Although our results provide clear evidence for the overall importance of motive force generation according to the hydraulic pressure theory, some motile phenomena exist in Amoeba proteus that cannot exclusively be explained by this mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222375
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    Paper (German National Licenses)
    Fulltext
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