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  • Cell & Developmental Biology  (1,170)
  • Biochemistry and Biotechnology  (614)
  • Animals
  • 1990-1994  (2,208)
  • 1991  (2,208)
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  • 1990-1994  (2,208)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Alpha-actinin and actin in the outer retina: A double immunoelectron microscopic study (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 15-25 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; microfilaments ; immunocytochemistry ; photoreceptors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin has many diverse functions in the outer retina. To help elucidate its organization in this area, we have investigated the extent of its association with the actin cross-linking protein alpha-actinin. Ultrathin sections of chicken retina were double-immunolabelled with monospecific antibodies against actin and alpha-actinin. The highest relative amount of alpha-actinin to actin label was measured in the adherens junctions between the individual retinal pigmented epithelial (RPE) cells and between the photoreceptor and Mueller cells; in the photoreceptor myoid; and in the RPE basal microvilli. The lowest amount was in the Mueller cell microvilli, the RPE apical processes, and in the photoreceptor ellipsoid. It is likely that the areas containing the highest ratio of alpha-actinin to actin labelling are where the actin filaments are most highly cross-linked into bundles and linked to the plasma membrane by alpha-actinin. Actin filaments terminate in these areas, and, except for the myoid region, they are involved in cell-cell or cell-substrate adherens junctions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180103
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  • 2
    Electronic Resource
    Electronic Resource
    Reorganization of cytoskeletal and junctional proteins during cochlear hair cell degeneration (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 215-227 
    Details
    ISSN: 0886-1544
    Keywords: guinea pig ; organ of Corti ; cytokeratins ; actin ; cingulin ; phalangeal scar ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Experiments were carried out to elucidate changes in cytoskeletal elements and intercellular junctions in the organ of Corti, when hair cells degenerate and phalangeal scars form. Hair cell damage was induced by exposing guinea pigs to high intensity noise. The spatial and temporal changes in the organization of micro-filaments, intermediate filaments, and tight junction-specific proteins were investigated using scanning and transmission electron microscopy and histochemistry. The results show that microfilaments, cytokeratins, adherens junctions, and tight junctions rearrange their distribution in damaged areas. From the temporal sequence of these changes it appears that phalangeal scars develop simultaneous with hair cell degeneration, and that the integrity of the luminal membranes in the organ of Corti is not interrupted. Each scar is formed by two supporting cells which expand and invade the sub-apical region of the dying hair cell. This region becomes cytokeratin-positive. The two supporting cells meet at the mid-line of the scar, where a new junctional complex is formed. The junctional complex consists of tight junction and adherens-type junction, but desmosomes are absent.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180307
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  • 3
    Electronic Resource
    Electronic Resource
    Decrease of internal free calcium and human sperm movement (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 228-240 
    Details
    ISSN: 0886-1544
    Keywords: Quin-2/AM ; spermatozoa ; calcium depletion ; motility ; flagellum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to elucidate the effects of calcium on the movement of human spermatozoa, studies were conducted using motile cells selected by swim-up migration at 37°C in 5% CO2 in air in a synthetic BWW medium containing 1.7 × 10-3 M CaCl2 or BWW without added calcium (BWW-Ca). Preliminary experiments have confirmed that the addition of EGTA (5 × 10-3; 10-2 M) to BWW medium decreased the intracellular calcium concentration ((Ca++)i) of spermatozoa, as measured in cells loaded with a fluorescent Ca++ indicator, Quin-2. Concomitant measurements of (Ca++)i and sperm movement (analysed by videomicrography at 200 f/s at room temperature) were carried out on Quin-2 loaded cells incubated in BWW-Ca medium plus EGTA (10-5 M; 10-4 M; 10-3 M). Under these conditions a decrease in (Ca++)i was observed and associated with a decrease in mean amplitude of lateral head displacement (ALH). Analysis using an automatic analyser (Hamilton Thorn at 37°C) confirmed these results: the percentage of spermatozoa swimming with ALH ≤ 6 μm is decreased when the external free calcium in BWW-Ca is decreased by the addition of 10-5 M, 10-4 M, or 10-3 M EGTA. Flagellar analysis of the sperm population characterized by ALH ≤ 6 μm showed a large proximal curvature of the tail associated with a low propagation wave velocity and a low beat frequency as compared to the spermatozoa with ALH ≤ 6 μm with similar progressive velocities. These characteristics result in a high flagellar beat efficiency (in terms of head displacement per beat). The disappearance of this pattern of movement when intracellular calcium is lowered indicates that calcium plays a complex role in the relationship between curvature and wave propagation. The ability of spermatozoa to modulate their movement in response to an alteration in the intracellular calcium level confirms the role of calcium in controlling flagellar movement in intact cells.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180308
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  • 4
    Electronic Resource
    Electronic Resource
    Microtubule binding and translocation by inner dynein arm subtype i1 (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 258-268 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; motility ; Chlamydomonas ; cilia ; ATPase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Structural, biochemical, and genetic evidence has demonstrated there are three inner dynein arm subforms, I1, I2, and I3, which differ in organization and composition (see Piperno et al.: J. Cell Biol. 110:379-389, 1990). Using dynein extracted from Chlamydomonas outer dynein armless mutant pf28, we have begun to define the structural and functional properties of isolated inner arm subforms. Inner dynein arm I1 was purified either by sucrose density gradient centrifugation or microtubule binding affinity. I1, composed of heavy chains 1α and 1β, sedimented at 21S and selectively bound to and cross-linked purified microtubules in and ATP-sensitive manner. Deep etch electron microscopy revealed that the 21S sedimenting fraction contained two-headed structures in which large globular heads are connected by long, flexible-stem domains. In contrast, components derived from I2 and I3 sedimented as a mixture of 11S particles with single globular heads which did not bind to purified microtubules. Both the 21S and 11S sedimenting fractions supported microtubule translocation in in vitro motility assays. In 1 mM MgATP the I1-containing fraction produced very slow microtubulegliding velocities (0.76 μm/sec) compared to the I2, I3-containing fraction (4.1 μm/sec).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180403
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  • 5
    Electronic Resource
    Electronic Resource
    Flagellar photoresponses of Chlamydomonas cells held on micropipettes: II. Change in flagellar beat pattern (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 269-278 
    Details
    ISSN: 0886-1544
    Keywords: high-speed microcinematography ; photophobic response ; phototaxis ; beat frequency ; rate of flagellar movement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In response to step-up as well as step-down blue or white light stimuli, changes of beat pattern were observed in the two flagella of Chlamydomonas. The front amplitude was either increased or decreased, always in reverse in the two flagella. Again, two opposite combinations of step-up and step-down responses were found roughly in parallel to the two types of beat frequency changes. It is shown that positive phototaxis is probably achieved by the first type [called type (+)] and negative phototaxis by the second one [called type (-)]. Comparative measurements have revealed that frequency is not only related to the rate of flagellar movement, but also to the beat pattern. The rate of movement may change in different ways in the recovery and in the effective stroke. Though beat frequency and pattern changes are opposite in the two types, the rates of movement of the two flagella during the effective stroke are not always. In type (-) divergent changes were found in the rates of effective stroke movement, perhaps indicating the involvement of an additional mechanism.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180404
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  • 6
    Electronic Resource
    Electronic Resource
    Post-mitotic cellular reorganisation in the diatom Cymatopleura solea: The role of microtubules and the microtubule centre (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 279-292 
    Details
    ISSN: 0886-1544
    Keywords: morphogenesis ; diatoms ; intracellular movement ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell division in Cymatopleura requires precise and major relocations of the nucleus and chioroplast which have been followed by time-lapse cinematography and with the electron microscope. These movements are (1) the premitotic nucleus migrating to one end of the cell; (2) after cytokinesis, the daughter nuclei moving back to the cell centre, often oscillating several times while establishing their final location; (3) the single chloroplast folding over and sandwiching the central nucleus; and (4) the folded end of the chloroplast stretching back to fill the empty half of the cell. In all cases, straight, actively moving, transient strands of cytoplasm are associated with the movement of the nucleus and chloroplast, and these often appear to be pulling on the surface or the fold of the chloroplast which undergoes transient distortion.These movements are rapid and colchicine-sensitive. Ultrastructurally, they appear to be mediated by the prominent microtubule centre (MC) and its associated cytoskeleton of microtubules (MTs) although MTs do not attach directly to either nucleus or chloroplast. The MC is located close to the moving nucleus. Later, it moves ahead of the moving chloroplast and its MTs ensheath the tip. Later still, it is seen embedded in the fold of the chloroplast. In all three situations, MTs from it are seen in the strands of cytoplasm radiating from this area across the vacuole. After these events, the MC resumes its usual interphase situation on the nuclear surface.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180405
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  • 7
    Electronic Resource
    Electronic Resource
    Announcement (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 319-320 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180408
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  • 8
    Electronic Resource
    Electronic Resource
    Neural crest cell galvanotaxis: New data and a novel approach to the analysis of both galvanotaxis and chemotaxis (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 121-133 
    Details
    ISSN: 0886-1544
    Keywords: modeling ; electric field ; directed motility ; information theory ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The galvanotaxis response of neural crest cells that had migrated out of the neural tube of a 56-hr-old quail embryo, onto glass coverslips was observed using time-lapse video microscopy. These cells exhibit a track velocity of about 7 μm/min and actively translocate toward the negative pole of an imposed DC electric field. This nonrandom migration could be detected for fields as low as 7 mV/mm (0.4 mV/cell lepgth). We find that this directional migration is independent of the speed of migration and have generated a rather simple mathematical equation that fits these data. We find that the number of cells that translocate at a given angle, Φ, with respect to the field is given by the equation N (Φ) = exp(a()0 + a1 cos Φ), where a1 is linearly proportional to the electric field strength for fields less than 390 mV/mm with a constant of proportionality equal to KG, the galvanotaxis constant. We show that KG = (150 mV/mm)-1, and at this field strength the cellular response is approximately half maximal. This approach to cellular translocation data analysis is generalizable to other directed movements such as chemotaxis and allows the direct comparison of different types of directed movements. This analysis requires that the response of every cell, rather than averages of cellular responses, is reported. Once an equation for N(Φ) is derived, several characteristics of the cellular response can be determined. Specifically, we describe (1) the critical field strength (390 mV/mm) below which the cellular response exhibits a simple, linear dependence on field strength (for larger field strengths, an inhibitory constant can be used to fit the data, suggesting that larger field strengths influence a second cellular target that inhibits the first); and (2) the amount of information the cell must obtain in order to generate the observed asymmetry in the translocation distribution (for a field strength of 100 mV/mm, 0.3 bits of information is required).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190207
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  • 9
    Electronic Resource
    Electronic Resource
    Pseudopodial activity at the active edge of migrating fibroblast is decreased after drug-induced microtubule depolymerization (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 152-158 
    Details
    ISSN: 0886-1544
    Keywords: video-enhanced contrast microscopy ; colcemid ; lamellipodia ; mitochondria ; intermediate filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It is known that depolymerization of microtubules by colcemid or other similar drugs abolishes polarization of pseudopodial activity in migrating fibroblasts. In this work the effect of colcemid on the intensity of protrusion and retraction of lamellipodia at the active edges of human fibroblasts migrating into the wound was investigated with video-enhanced contrast microscopy. To characterize the pseudopodial activity quantitatively the outlines of the active edges in the pairs of frames taken at adjacent 20-sec intervals were compared and mean areas of protrusions and retractions per unit length of the perimeter of the edge were measured. The mean rates of protrusions and retractions were 4-6 times less in colcemid-treated cells than in controls. Thus, microtubules depolymerized by colcemid, and/or intermediate filaments undergoing perinuclear collapse in the presence of this drug, are essential not only for the restriction of pseudopodial activity to one particular zone of the cell edge but also for the development of maximal activity in this zone.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190303
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  • 10
    Electronic Resource
    Electronic Resource
    βVLDL uptake by pigeon monocyte-derived macrophages: Correlation of binding dynamics with three-dimensional ultrastructure (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 139-151 
    Details
    ISSN: 0886-1544
    Keywords: lipoprotein ; receptor-mediated endocytosis ; nonspecific endocytosis ; microvilli ; membrane ruffles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endocytosis of pigeon beta migrating very-low-density lipoprotein (βVLDL) by monocyte-derived macrophages (monocyte/macrophages), cultured from Random Bred White Carneu (RBWC) pigeons, occurs by both coated and non-coated regions of the plasma membrane (Henson et al.: Exp. Mol. Pathol. 51:243-263, 1989). Secondary to binding, the βVLDL is translocated to lysosomes for degradation. Ultimately these events lead to foam cell formation in vitro. Utilizing video-enhanced contrast light microscopy in conjunction with whole mount intermediate-voltage transmission electron microscopy (IVEM) and high-resolution scanning EM, the dynamics of βVLDL binding have been correlated with ultrastructure. Beta VLDL conjugated to gold colloids was visualized at the surface of living cells by using Allen video-enhanced contrast-differential interference contrast microscopy (AVEC-DIC). Subsequent to AVEC-DIC, direct observation of the identical cells by IVEM and SEM was facilitated through the use of gold finder grids, and these EM observations confirmed identification of the videoobserved βVLDL particles.Upon addition of βVLDL, pigeon monocyte/macrophages underwent gross morphological changes. These changes were recorded by video as movements at the cytoplasmic periphery, and the movements involved extension of microvilli, expression of retraction fibers, and elaboration of membrane ruffles. When secondarily observed by stereo (3-D) IVEM and SEM, the identification of microvilli, retraction fibers, and membrane ruffles was confirmed and the lipoprotein-gold conjugates were associated with these ligand-induced membrane structures. Beta VLDL-gold conjugates were also associated with pit-like regions at the base of microvilli, while at the base of ruffles, βVLDL-gold conjugates were located in membrane invaginations and cytoplasmic vesicles.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190302
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