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  • Wiley-Blackwell  (12,154)
  • 1990-1994  (12,154)
  • 1970-1974
  • 1965-1969
  • 1990  (12,154)
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  • 1990-1994  (12,154)
  • 1970-1974
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 7-11 
    ISSN: 0886-1544
    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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  • 3
    ISSN: 0886-1544
    Keywords: centrosome ; cytaster ; MTOG ; pericentriolar material ; 51 kD protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Miniasters formed in mitotic sea urchin egg after treatment with 5% hexylene-glycol were investigated with the combined techniques of indirect immunofluo-rescence using anti-tubulin and anti-51 kD protein antibodies and electron microscopy.The formation of miniasters was dependent on the mitotic cycle. In the cytoplasm of eggs treated with hexyleneglycol at early prometaphase, a small number of microtubule fragments was observed, whereas in those treated at pro-metaphase, many miniasters and microtubule fragments were seen. When treated at metaphase, we found a great number of miniasters: 250-350 in one egg. In contrast, no miniasters were seen in eggs treated at anaphase, although many long microtubules that spread throughout the cytoplasm were observed. In the eggs treated at telophase, we scarcely noticed microtubule structures in the cytoplasm. In the center of miniasters, granules were found, showing the same size and electron density as those of the microtubule-organizing granules (MTOGs). Furthermore, the 51 kD protein, a component of the centrosome and mitotic spindle, was observed to be localized in the region of miniasters.
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  • 4
    ISSN: 0886-1544
    Keywords: villin ; fimbrin ; myosin I ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The assembly of the intestinal microvillus Cytoskeleton was examined during the differentiation of enterocytes along the crypt-villus axis in adult chicken duodenum using light and electron microscopic immunolocalization techniques. Using antibodies reactive with villin, fimbrin, and the heavy chain (he) of brush border (BB) myosin I (110K-calmodulin complex) and rhodamine-conjugated phalloidin as a probe for F-actin, we determined that while actin, villin, and fimbrin were all localized apically along the entire axis, BB myosin I (he) did not assume this localization until the crypt-villus transition zone. In addition to their localization at the BB surface, all four proteins were present at significant levels along the lateral margins of enterocytes along the entire crypt-villus axis, suggesting that these proteins may be involved in the organization and function of the basolateral membrane Cytoskeleton as well. The pattern of expression of the microvillar coreproteins along the crypt-villus axis in the adult was comparable to that seen in the intestine of the late stage chicken embryo and suggests that a common program for brush border assembly may be used in both modes of enterocyte differentiation.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 41-50 
    ISSN: 0886-1544
    Keywords: adhesion plaques ; cytoskeletal interactions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vinculin and talin are adhesion plaque proteins which have been shown to interact with each other in vitro. In order to begin to investigate where the talin-binding domain is in vinculin, vinculin was digested with Staphylococcus aureus V8 protease to generate two major fragments of 85 and 30 kDa, and these fragments were purified. Nitrocellulose overlays with 125I-talin and the 125I-85 kDa vinculin fragment and sucrose density gradient centrifugation demonstrated that the talin-binding domain was localized to the 85 kDa vinculin fragment. Quantification of 125I-talin binding in the overlays showed that four times more talin bound to the 85 kDa fragment as compared to intact vinculin. Competitive immunoprecipitation experiments demonstrated that unlabeled 85 kDa fragment, was about three fold more effective at competing for 125I-85 kDa binding to talin than was unlabeled vinculin. These results suggest that the 30 kDa fragment inhibits the vinculin-talin interaction even though the talin-binding domain is localized in the 85 kDa fragment.
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  • 6
    ISSN: 0886-1544
    Keywords: rat liver cells ; immunoprecipitation ; immunocytochemistry ; membrane-bound proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Confluent and proliferatively quiescent T51B rat liver epithelial cells provide a cellular model for the study of epidermal growth factor (EGF) effects in non-neoplastic cells. Immunoreactive calpactin II, a well-known substrate for EGF-receptor kinase, was found predominantly in the cytosol, although a second im-munoreactive pool was found in a Triton X-100-extractable membrane fraction. Stimulation with EGF resulted in a rapid and transient (2-;5 min) formation of ruffles at the cell surface and at the cell-cell contacts. Both calpactin II and filamentous actin were found co-localized at the membrane ruffles. Immunopre-cipitations of membrane-bound calpactin II from 32P-labeled cells indicate a transient EGF-dependent phosphorylation of calpactin II correlating with membrane ruffling. These results suggest a temporal (2-5 min) function for calpactin II at the plasma membrane during the EGF-induced mitogenesis of T51B cells.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 9
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 10
    ISSN: 0886-1544
    Keywords: organelle motors ; nucleoside triphosphates ; fast axonal transport ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Video microscopy of isolated axoplasm from the squid giant axon permits correlated quantitative analyses of membrane-bounded organelle transport both in the intact axoplasm and along individual microtubules. As a result, the effects of experimental manipulations on both anterograde and retrograde movements of membrane-bounded organelles can be evaluated under nearly physiological conditions. Since anterograde and retrograde fast axonal transport are similar but distinct cellular processes, a systematic biochemical analysis is important for a further understanding of the molecular mechanisms for each. In this series of experiments, we employed isolated axoplasm of the squid to define the nucleoside triphosphate specificity for bidirectional organelle motility in the axon. Perfusion of axoplasm with 2-20 mM ATP preserved optimal vesicle velocities in both the anterograde and retrograde directions. Organelle velocities decreased to 〈50% of optimal values when the axoplasm was perfused with 10-20 mM UTP, GTP, ITP, or CTP with simultaneous depletion of endogenous ATP with hexokinase. Under the same conditions, TTP and ATP-γ-S were unable to support significant levels of transport. None of the NTPs tested had a differential effect on anterograde vs. retrograde movement of vesicles. Surprisingly, several inconsistencies were revealed when a comparison was made between these results and nucleoside triphosphate specificities that have been reported for putative organelle motors by using in vitro assays. These data may be used in conjunction with data from well-defined in vitro assays to develop models for the molecular mechanisms of axonal transport.
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  • 11
    ISSN: 0886-1544
    Keywords: photomovement ; population method ; stop response ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Phototaxis of the unicellular alga Chlamydomonas was studied with subsecond time resolution by using a newly developed taxigraph. The taxigraph determines the cell density in a particular volume element of a cuvette by measuring the amount of scattered light originating from the cells in this region. When the cell density is kept below 106/ml, a linear relationship exists between the scattered photon irradiance and the number of scattering particles. Time-dependent scattering changes can be used to determine direction and extent of phototactic activity as well as the time course of various adaptation processes. This communication describes design and performance of the taxigraph in detail and compares results obtained from Chlamydomonas cell populations with those obtained from single-cell analysis by using a computer-aided motion analysis system.The high time resolution of the taxigraph permits the study of rapid adaptational processes. Chlamydomonas strain 806 cells, which have been reported to show exclusively negative phototaxis, were found to turn transiently towards the light upon a rapid change in irradiance, before eventually moving away from it. The duration of the initial positive phototactic response was critically dependent on the magnitude of the irradiance increment. Adaptation to a step-up stimulus was consistently faster than to a step-down stimulation. The statistical nature of the switch from positive to negative phototaxis is demonstrated by single-cell observation.Different adaptation levels were characterised by stimulus-response curves, either in the presence of a constant background or following a defined delay after long previous irradiation. To describe the observed behaviour the existence of two adaptation processes, occurring on a vastly different time scale, must be anticipated: a rapid (seconds) background adaptation and a slow desensitisation in steady light which is completed in 30-40 min.
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  • 12
    ISSN: 0886-1544
    Keywords: cytoskeleton ; chemotaxis ; polymerization ; motility ; nucleation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Definition of the kinetics of ligand-activated actin polymerization in the neutrophil is important for ultimately understanding the mechanisms utilized for regulation of actin polymerization in this non-muscle cell. To better define the kinetics of formyl peptide (fMLP) -induced actin polymerization in neutrophils we determined F-actin content at 5 second intervals after activation of human neutrophils with a range (10-11-10-9M) of fMLP concentrations. The state of actin polymerization was monitored by quantifying F-actin content with NBD phallacidin binding in both flow cytometric and extraction assays. Results demonstrate three successive kinetic periods of fMLP-induced actin polymerization in neutrophils, a lag period, a 5 second period when rate of polymerization is maximal, and a period of declining rate of actin polymerization as F-actin content approaches a maximum. The duration of the lag period, the maximum rate of polymerization, and the maximum extent of polymerization all depend upon the fMLP concentration. The lag period varies from 0 to 12 seconds and is followed in 5-10 seconds by a 5 second burst of actin polymerization when the rate is as great as 9% increase in F-actin content per second. After the 5 second burst of polymerization, the rate of polymerization rapidly declines. The study defines three distinct kinetic periods of fMLP-induced actin polymerization during which important rate-limiting biochemical events occur. The mechanistic and motile implications of kinetic periods are discussed.
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  • 13
    ISSN: 0886-1544
    Keywords: sea urchin ; centrosome ; immunofluorescence microscopy ; barrel-shaped spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: T-1 induces modifications in the shape of the centrosome at division in fertilized eggs of the North American sea urchin, Lytechinus pictus. Phase contrast microscopy observations of mitotic apparatus isolated from T-1treated (1.7-8.5μM) eggs at first division shows that the centrosomes already begin to spread or to separate by prophase and that the mitotic spindle is barrel-shaped. When eggs are fertilized with sperm that have been pretreated with T-1, the centrosomes become flattened; the spindles are of normal length. Immunofluorescence microscopy using an anti-centrosomal monoclonal antibody reveals that T-l modifies the structure of the centrosome so that barrel-shaped spindles with broad centrosomes are observed at metaphase, rather than the expected focused poles and fusiform spindle. Higher concentrations of T-l induce fragmentation of centrosomes, causing abnormal accumulation of microtubules in polar regions. These results indicate that T-l directly alters centrosomal configuration from a compact structure to a flattened or a spread structure. T-l can be classified as a new category of mitotic drugs that may prove valuable in dissecting the molecular nature of centrosomes.
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  • 14
    ISSN: 0886-1544
    Keywords: mitosis ; mitotic apparatus ; monoclonal antibodies ; sand dollar egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The heterogeneity of mitotic microtubules in dividing sea urchin eggs was investigated by indirect immunofluorescence using five anti-α-tubulin (YL1/2, DM1A, E3B8, D2D6, and 6-11B-1) and two anti-β-tubulin (E6B6 and DM1B) antibodies. These antibodies were divided into four classes in regard to the different immunofluorescent staining patterns: class I, which strongly stained both the spindle and aster (YL1/2, DM1A, E3B8 and E6B6); class II, which strongly stained the spindle but weakly stained the aster (D2D6); class III, which stained only the aster (DM1B); and class IV, which did not stain the mitotic apparatus (6-11B-1). These results suggest that tubulin isotypes are distributed differently in the sea urchin mitotic microtubules and that α-tubulin isotype(s) recognized by D2D6 is (are) localized mainly in spindle microtubules, whereas β-tubulin isotype(s) recognized by DM1B is (are) found only in astral microtubules.
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  • 15
    ISSN: 0886-1544
    Keywords: microinjection ; actin cytoskeleton ; degradation of stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gelsolins, prepared from a number of different sources, showed similar severing activity on F-actin in vitro or on stress fibers of detergent-extracted cells but differed in their effects on actin in stress fibers of microinjected cells. When human gelsolin isolated from plasma was injected into cells in a Ca++-containing buffer, stress fibers were degraded, the cellular morphology was changed, and numerous actin patches appeared. These effects were particularly striking when the Ca++-insensitive N-terminal proteolytic fragment of this gelsolin was injected. By contrast, Ca++-sensitive gelsolins isolated from human platelets, pig stomach smooth muscle and pig plasma showed no comparable activity. Furthermore, the Ca++-independent N-terminal proteolytic fragments prepared from these gelsolins also had no effect despite their in vitro actin severing activity. Most striking was the finding that human plasma gelsolin expressed in E. coli did not degrade stress fibers, in contrast to the same protein isolated from plasma; nor was there any stress fiber disruption observed with the N-terminal half of human gelsolin expressed in Escherichia coli.The different behavior of these gelsolins in cells cannot be explained by sequence diversity between plasma and cytoplasmic forms, nor by variability in the Ca++ sensitivity of the preparations. It suggests the presence of factors, as yet unidentified, that may regulate gelsolin activity in the cytoplasm of living cells and discriminate between gelsolins of different origin. Such discrimination could be achieved as a result of post-translational modification of the gelsolin; only in this way can differences between apparently identical proteins isolated from human plasma and expressed in E. coli be reconciled.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 6-10 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 18
    ISSN: 0886-1544
    Keywords: intermediate filaments ; desmin ; cytoskeleton ; protein A-gold ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In avian smooth muscle cells, desmin-containing intermediate filaments (IFs) are a prominent component of the cytoskeleton and are readily seen in several domains, inclu-ding the axial intermediate filament bundle (IFB). Both the nucleus and some of the mitochondria are partly surrounded by elements of the IFB. By using anti-desmin and protein-A-colloidal gold labeling, we have identified intermediate filaments that form linkages with the nuclear envelope and with mitochondria. These linkage regions seem to occupy a proportionately greater part of the mitochondrial surface than of the nuclear envelope. The existence of these linkages in smooth muscle cells is consistent with results that support similar linkages to mitochondria and other cellular structures in various cells that contain either vimentin or keratin IFs. These linkages could functionally restrain or assist in homeostatically restoring organelles to their normal position after the rearrangement that accompanies the substantial shortening of smooth muscle cells.
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  • 19
    ISSN: 0886-1544
    Keywords: detyrosinated α-tubulin ; Drosophila embryo ; confocal microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of microtubules (MTs) enriched in detyrosinated α-tubulin (Glu-tubulin) was studied in Drosophila embryos by immunofluorescence micro-scopy by using a monoclonal antibody (ID5) which was raised against a 14-residue synthetic peptide spanning the carboxyterminal sequence of Glu-tubulin (Wehland and Weber: J. Cell Sci. 88:185-203, 1987). While all MT arrays contained tyrosinated α-tubulin (Tyr-tubulin), MTs rich in Glu-tubulin were not found during early stages of development even by using an image intensification camera. Elevated levels of microtubular Glu-tubulin were first detected after CNS condensation in neurone processes. In addition, sperm tails, which remained remarkably stable inside the embryo until late stages of development, were decorated by ID5. This was in marked contrast to the distribution of microtubule arrays containing acetylated α-tubulin, which could already be detected during the cellular blastoderm stage. Additional experiments with taxol suggested that the absence of MTs rich in Glu-tubulin during early stages of development was not due to the rapid turnover rate of MTs, which would be too fast for α-tubulin to be detyrosinated. The possible significance of the differential detyrosination and acetylation of microtubules during development is discussed.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 159-163 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 95-105 
    ISSN: 0886-1544
    Keywords: colchicine-tubulin ; neurite growth ; process extension ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have injected process-bearing PC12 cells with colchicine-tubulin mixed with either fluorescein-dextran or a rhodamine-labelled tubulin analogue to determine the role of microtubule polymerization in neurite elongation. Colchicine-tubulin is a specific, substoichiometric poison of microtubule assembly. We have shown that colchicine-tubulin does not cause existing PC12 microtubules to disassemble, and yet can inhibit the assembly of rhodamine-tubulin injected along with it. In population s'udies of neurite outgrowth in injected and uninjected cells, we find that colchicine-tubulin substantially inhibits neurite extension from injected cells over a wide variety of concentrations. In acute time-course studies of injected cells, we find that colchicine-tubulin does not block neurite outgrowth until the injectate reaches the neurite tip. Thereafter, however, it blocks process elongation completely. Thus we can conclude that microtubule polymerization in the region of the growth cone is an important element in neurite elongation. While polymerization at the cell body may be important in supplying subunits to the distal neurite, it does not play a direct role in process extension.
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  • 22
    ISSN: 0886-1544
    Keywords: Wheat germ agglutinin ; Limax flavus agglutinin ; axonal cytoskeleton ; actin ; cytochalasin D ; axoplasmic transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Goldfish retinal ganglion cell (RGC) axons regenerating in vitro exhibit a novel mode of axoplasmic transport that entails a rapid bidirectional bulk redistribution of axoplasm, “packaged” as protruding varicosities and non-protruding phase-dense inclusions (Koenig et al.: J. Neurosci. 5:715-729, 1985; Edmonds and Koenig Brain Res. 406:288-293, 1987). We have used phase-contrast video microscopy to study transmembrane effects of surface-binding lectins on bulk transport and transport of single visible organelles in RGC axons. Our findings show that certain lectins which crosslink sialoglycoconjugates, such as wheat germ agglutinin (WGA) and the more specific sialic acid-binding lectin Limax flavus agglutinin (LFA), induce a rapid inhibition of transport activity. The LFA-induced inhibition of transport can be reversed by appropriate simple sugar haptens, and can also be antagonized by pretreatment with cytochalasin D. One of the consequences of LFA binding is an increase in RITC-conjugated phalloidin fluorescence staining of preterminal axons. The latter observation in conjunction with the antagonistic action of cytochalasin D suggests that one possible explanation for the transmembrane arrest of transport induced by crosslinking of surface sialoglycoconjugates may involve a polymerization and/or reorganization of the actin filament network which hinders translocation of mobile axoplasmic components.
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 24
    ISSN: 0886-1544
    Keywords: Cell motility ; chemotaxis ; mathematical model ; alveolar macrophages ; C5a ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Phenomenological parameters from a mathematical model of cell motility [1] are used to quantitatively characterize chemosensory migration responses of rat alveolar macrophages migrating to C5a in the linear under-agarose assay, simultaneously at the levels of both single cells and cell populations. This model provides theoretical relationships between single-cell and cell-population motility parameters. Our experiments offer a critical test of these theoretical linking relationships, by comparison of results obtained at the cell population level to results obtained at the single-cell level.Random motility of a cell population is characterized by the random motility coefficient, μ (analogous to a particle diffusion coefficient), whereas single-cell random motility is described by cell speed, s, and persistence time, P (related to the period of time that a cell moves in one direction before changing direction). Population chemotaxis is quantified by the chemotactic sensitivity, χo, which provides a measure of the minimum attractant gradient necessary to elicit a specified chemotactic response. Single-cell chemotaxis is characterized by the chemotactic index, CI, which ranges from 0 for purely random motility to 1 for perfectly directed motility. Measurements of cell number versus migration distance were analyzed in conjunction with the phenomenological model to determine the population parameters while paths of individual cells in the same experiment were analyzed in order to determine the single-cell parameters.The parameter μ shows a biphasic dependence on C5a concentration with a maximum of 1.9 × 10-8 cm2/sec at 10-11 M C5a and relative minima of 0.86 × 10-8 cm2/sec at 10-7 M C5a and 1.1 × 10-8 cm2/sec in the absence of C5a; s and P remain fairly constant with C5a concentration, with s ranging from 2.1 to 2.5 μm/min and P varying from 22 to 32 min. χo is equal to 1.0 × 10-6 cm/receptor for all C5a concentrations tested, corresponding to 60% correct orientation for a difference of 500 bound C5a receptors across a 20 μm cell length. The maximum CI measured was 0.2.Values for the population parameters μ and χo were calculated from single-cell parameter values using the aforementioned theoretical linking relationships. The values of μ and χo calculated from single-cell parameters agreed with values of μ and χo determined independently from population migrations, over the full range of C5a concentrations, confirming the validity of the linking equations. Experimental confirmation of such relationships between single-cell and cell-population parameters has not previously been reported.
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  • 25
    ISSN: 0886-1544
    Keywords: HeLa cells ; microtubule-associated proteins ; MAPIA ; vimentin filaments ; cytokeratin filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A novel monoclonal antibody, designated M1.4, recognizes the high molecular weight microtubule-associated protein MAPIA (ca. Mr 380 kD) in both bovine and rat brain. In HeLa cells, however, M1.4 binds to a 240 kD polypeptide on immunoblots and co-localizes with both vimentin and cytokeratin filaments using double-label immunofluorescence microscopy. Immunoelectron microscopy indicates that the 240 kD polypeptide localizes along bundled intermediate filaments in a periodic manner. Two-dimensional electrophoretic analysis indicates that the 240 kD polypeptide has a basic pI of 7.7. When HeLa cell intermediate filaments are isolated using standard non-ionic detergent/high-salt conditions the 240 kD polypeptide does not sediment with the intermediate filaments, unlike the established intermediate filament-associated protein plectin. Immunoblot analysis with M1.4 shows the 240 kD polypeptide is expressed in a number of mammalian cell lines. Additionally, double-label immunofluorescence shows the 240 kD polypeptide to associate with vimentin filaments in African Green Monkey kidney (CV-1) and JC neuroblastoma cells. Due to its unique biochemical and biological characteristics, the 240 kD polypeptide is clearly a novel intermediate filament-associated protein for which we have proposed the designation gyronemin (Gr.gyros: around: nemin: filament).
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  • 26
    ISSN: 0886-1544
    Keywords: circumferential microfilament bundles ; intercellular adhesion ; cytoskeleton ; junctional complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The junctional complexes in chick retinal pigment epithelial (RPE) cells in situ contain unusually large zonulae adhaerentes (ZAs) composed of subunits termed zonula adhaerens complexes (ZACs). To determine whether the properties of the ZAs differ between RPE cells which contain ZACs, and MDCK cells which lack ZACs, we investi-gated the effects of treatment with trypsin and/or low Ca2+ by transmission electron microscopy and staining for F-actin. Treatment of RPE cells for 1 h with trypsin alone has no apparent effect on the morphology of the ZA in either MDCK or RPE cells. In contrast to the ZAs in MDCK cells, which split after 3 min in low Ca2+, the ZAs in chick RPE cells stay intact even after 2 h, although the intermembrane discs, i.e., the extracellular components of the ZACs, are no longer visible. After 30 min of treatment with trypsin and low Ca2+, the ZAs split in both cell types. The CMBs start to contract, translocate toward the cell interior, and eventually disappear. This process continues even when the RPE cells are returned to normal medium. New ZAs, composed of ZACs, form between RPE cells 3 h after return to normal medium. These findings suggest that the ZACs in the ZAs of RPE cells are not directly responsible for the increase in resistance to low Ca2+. They also show that the ZA-junctions in RPE cells are not only structurally different from those previously examined, but also behave differently in response to experimental manipulation.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 59-67 
    ISSN: 0886-1544
    Keywords: Polytoma papillatum ; Megaselia scalaris ; protofilament ; mitosis ; meiosis ; spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The association of incomplete microtubule assemblies with either another incom-plete structure or complete microtubules was studied in two organisms, the phytoflag-ellate Polytoma papillatum and the phorid fly Megaselia scalaris, using transmission electron microscopy. In the alga, hook-shaped appendages on cytoplasmic and spindle microtubules were detected. These resulted from the lateral association of a curved ribbon of protofilaments with the surface of a complete microtubular wall. In the fly, an S-shaped protofilament sheet was found embedded in the kinetochore plate of a prometaphase I spematocyte. Tracing of the S-shaped element towards the spindle pole revealed that it was formed by the lateral junction of two curved protofilament sheets. In all cases, the C-shaped protofilament sheets represented the endings of complete micro-tubules. Incomplete microtubules are generally considered as representing intermediates of microtubule assembly and disassembly. Since high molecular weight proteins are believed to be responsible for maintaining microtubule-microtubule spacing, it is hypo-thesized that the endings of growing and shrinking microtubules are sparsely studded with these proteins; their depletion allows lateral microtubule contacts. In addition, the microtubule-microtubule contacts may be rendered possible by the flexibility of the slender elongated microtubule-associated molecules. Relatively long C-shaped proto-filament appendages (0.6-1.4 μm) were detected in this study. Therefore, it is plausible to assume that the protofilament sheets are stabilized by contact with one another or with an intact tubule wall.
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  • 28
    ISSN: 0886-1544
    Keywords: intermediate filaments ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin spermatozoa, eggs, and embryos were labeled with the universal antibody against the intermediate filament proteins (anti-IFA) described by Pruss et al. [Cell 27:419-428, 1981] and with anti-beta-tubulin. Localization of these antibodies was by indirect immunofluorescence microscopy. Cytoskeleton of unfertilized eggs, prepared according to a procedure adapted from Kane [Exp. Cell Res. 162:495-506, 1986] or as described by Dufresne et al. [Biochem. Cell Biol. 66:780-791, 1988], and reacted with the anti-IFA demonstrate a uniformly stained background except for the nuclear areas, which appear as dark rings. During the first cell cycle, the anti-IFA staining pattern coincides with that of spindle-associated tubulin but not with the cortical pattern of microtubules. Swimming embryos reacted with the anti-IFA show a labeling located on the cilia and within the cytoplasm of each individual cell of the larva. In spermatozoa, the labeling occurs all along the flagellae. Immunoblots of proteins from eggs and embryos reveal one major protein of 117 kDa and sometimes a component of 66 kDa, both of which cosediment with tubulin during the isolation procedure of microtubules described by Vallee and Bloom [Proc. Natl. Acad. Sci. USA 80:6259-6263, 1983]. These data show that proteins homologous to the intermediate filament proteins reported in vertebrate cells are present in both gametes of sea urchins. The specific localization ofthese proteins in the spindle, the flagella, and the cilia suggest that they may play a significant role in the organization and function of the microtubular lattice of the spermatozoa and of the embryo.
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  • 29
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    Cell Motility and the Cytoskeleton 17 (1990), S. 142-142 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 30
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    Cell Motility and the Cytoskeleton 17 (1990), S. 147-149 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 31
    ISSN: 0886-1544
    Keywords: tubulin heterogeneity ; neural differentiation ; neuronal microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five β-tubulin isotypes are expressed differentially during chicken brain development. One of these isotypes is encoded by the gene cβ4 and has been assigned to an isotypic family designated as Class III (βIII). In the nervous system of higher vertebrates, βIII is synthesized exclusively by neurons. A βIII-specific monoclonal antibody was used to determine when during chick embryogenesis cβ4 is expressed, the cellular localization of βIII, and the number of charge variants (isoforms) into which βIII can be resolved by isoelectric focusing. On Western blots, βIII is first detectable at stages 12-13. Thereafter, the relative abundance of βIII in brain increases steadily, apparently in conjunction with the rate of neural differentiation. The isotype was not detectable in non-neural tissue extracts from older embryos (days 10-14) and hatchlings. Western blots of protein separated by two-dimensional gel electrophoresis (2D-PAGE) reveal that the number of βIII isoforms increases from one to three during neural development. This evidence indicates that βIII is a substrate for developmentally regulated, multiple-site posttranslational modification. Immunocytochemical studies reveal that while cβ4 expression is restricted predominantly to the nervous system, it is transiently expressed in some embryonic structures. More importantly, in the nervous system, immunoreactive cells were located primarily in the non-proliferative marginal zone of the neural epithelia. Regions containing primarily mitotic neuroblasts were virtually unstained. This localization pattern indicates that cβ4 expression occurs either during or immediately following terminal mitosis, and suggests that βIII may have a unique role during early neuronal differentiation and neurite outgrowth.
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  • 32
    ISSN: 0886-1544
    Keywords: microtubule disassembly ; tubulin-binding sites ; protein concentration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The concentration of estramustine phosphate required to inhibit the assembly or to induce the disassembly of chick brain MAP2:tubulin microtubules is markedly dependent upon the microtubule protein concentration. Analysis of this relationship shows that estramustine phosphate and tubulin compete for common MAP2 sites, that MAP2 can bind 5-6 moles-mole-1 estramustine phosphate, and that the Kd of these sites is ≏ 20 μM estramustine phosphate. It is proposed that two molecules of estramustine phosphate interact with each of the three tubulin-binding sites of MAP2 and inhibit the MAP2:tubulin interaction by neutralising two highly conserved basic residues.
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  • 33
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    Cell Motility and the Cytoskeleton 17 (1990), S. 187-196 
    ISSN: 0886-1544
    Keywords: axonemal shape changes ; Ca/Ba/Sr ; macrocilia ; Beroë ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Macrocilia of the ctenophore Beroë undergo Ca/Ba/Sr-dependent activation of ciliary beating and microtubule sliding disintegration [Tamm, J. Comp. Physiol. A163:23-31. 1988a: Tamm, Cell Motil. Cytoskeleton 11:126-138, 1988b; Tamm, Cell Motil. Cytoskeleton 12:104-112, 1989: Tamm and Tamm, Proc. Natl. Acad. Sci. U.S.A. 86:6987-6991, 1989]. Here we report that detergent-extracted macrocilia show an ATP-independent conformational change in response to high concentrations of Ca. Ba. or Sr ions. When applied locally by iontophoresis, these ions induce a rapid planar curvature of the distal end of the macrociliary shaft, followed by a slower relaxation to the rest position. Tip curling occurs in a direction opposite to the physiological Ca/Ba/Sr response. When applied uniformly in the bath, a threshold concentration of 10-1 M Sr is required to induce curling of the tip, and the distal ends remain curved. Calmodulin antagonists do not inhibit the tip curling response.Previous workers found that Ca induces changes in the helical shape of isolated doublet microtubules [Miki-Noumura and Kamiya, Exp. Cell Res. 97:451-453, 1976: Miki-Noumura and Kamiya. J. Cell Biol. 81:355-360, 1979; Takasaki and Miki-Noumura. J. Mol. Biol. 158:317-324, 1982] and sperm axonemes [Okuno and Brokaw, Cell Motil. 1:349-362. 1981] and suggested that conformational changes in microtubules may play a role in Ca regulation of ciliary motility. We propose that the Ca/Ba/Sr-induced curling of the macrociliary tip is due to similar helical changes of doublet microtubules, some of which in macrocilia are prevented from sliding by permanent connections (compartmenting lamellae) between adjacent axonemes within the shaft. Although the tip curling response does not appear to be directly relevant to the physiological Ca response of macrocilia, it provides a novel system for investigating Ca-induced conformational changes of microtubules independent of dynein-powered active sliding.
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  • 34
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    Cell Motility and the Cytoskeleton 17 (1990), S. 227-235 
    ISSN: 0886-1544
    Keywords: mitosis ; kinetochores ; cell division cycle ; protein phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Antibodies to both the C-terminal and the N-terminal regions of the 34 kd serinethreonine specific protein kinase, p34cdc2, were used to study the distribution of this protein in dividing cells and isolated chromosomes of the Indian muntjac. p34cdc2 was found to be present throughout the cytoplasm of dividing cells. In addition, a portion of cellular p34cdc2 was localized to the centrosome, kinetochore, and intercellular bridge and along kinetochore-to-pole microtubules during cell division. Tubulin-denuded metaphase kinetochores retained their association with p34cdc2. The detection of p34cdc2 within a variety of domains of the mitotic apparatus, in addition to the previous reported association with the centrosome [Bailly et al., EMBO J. 8:3985-3995, 1989; Raibowol et al., Cell 57:393-401, 1989] suggests that p34cdc2 may play a role in events associated with anaphases A and B as well as with the transition between interphase and mitosis.
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  • 35
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    Cell Motility and the Cytoskeleton 17 (1990), S. 250-263 
    ISSN: 0886-1544
    Keywords: myosin ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present microinjection data in support of an indirect approach by which cytoplasmic protein interactions important in the processes of bone resorption can be elucidated. Three polyclonal antibodies (M1, M3, M5) raised against myosin II from perfused rat liver differently affected the actin-activated Mg ATPase of myosin II. These antibodies microinjected into isolated rat osteoclasts affected osteoclast morphology and activity in bone resorption. M1, which completely inhibited myosin ATPase activity at a antibody:myosin ratio of 10:1, initially promoted the extension/retraction motility of lamellipodia but eventually reduced the spread area of osteoclasts along the substrate after 20 hr. M3, which inhibited ATPase activity by 70%, had similar effects; however, M5, which weakly inhibited ATPase activity, neither promoted extension/retraction nor reduced spread area of osteoclasts. Immunofluorescence showed that these antibodies removed myosin II from the majority of actin filaments in injected osteoclasts. Because antibodies that did not bind to a myosin II column had little effect on the extension/retraction of lamellipodia or the osteoclast spread area, these data suggest that myosin II participates in the stabilization of osteoclast lamellipodia along the substrate. M1 injection strongly inhibited injected osteoclasts from excavating resorption lacunae in bone slices, compared to control antibody. M3 and M5 were less effective but also inhibited bone resorption. These data show that myosin II is functionally important in bone resorption and that the osteoclast-differentiated activity of bone resorption is a more sensitive assay for myosin activity than lamellipodia motility or cell morphology.
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  • 36
    ISSN: 0886-1544
    Keywords: bundles ; cytomechanics ; photobleaching ; rheology ; viscoelasticity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously established [Cortese and Frieden, J. Cell Biol. 107:1477-1487, 1988] that actin gels formed under shear are microheterogeneous. In this study, the effect of cross-linking (by chicken gizzard filamin), severing (by plasma gelsolin), and shear on actin microheterogeneity are investigated using fluorescence photobleaching recovery and video microscopy. We find that filamin and shear form microheterogeneous F-actin:gelsolin gels by different mechanisms. Bundling of actin:gelsolin filaments by filamin can be explained by an increase in the apparent length of the filaments due to interfilament binding, resulting in a decrease of the polymer number concentration at which filaments organize into anisotropic phases. Some intrafilament binding of filamin to actin filaments may also be present, and those filaments coated with filamin immobilize more slowly than actin under the same polymerization conditions. The length of F-actin/gelsolin filaments seems to be a major factor in controlling the extent of bundling relative to network formation. In contrast, the effect of shear on the microheterogeneity of actin:gelsolin filaments is consistent with our previous proposal that shear aligns actin filaments, allowing filament-filament interactions and phase formation to occur. Short filaments are unable to organize into branched actin networks, but they can create large aggregates under low shear. Longer actin filaments will exist as networks with variable levels of branching and are less sensitive to shear. The effect of the intensity of a shear field on the spatial distribution of actin may involve a progressively more random orientation of actin molecules and bundles. A regular pattern develops across the sample at low shear rates (0.04-1.39 s-1), and becomes very irregular at higher shear rates (〉 10 s-1). We suggest here that actin-binding proteins and shear can control the transition between isotropic networks and anisotropic phases by their effect on apparent length and local filament concentration, and also that this transition can have substantial effects on the resistance of cells to mechanical stress.
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  • 37
    ISSN: 0886-1544
    Keywords: bovine trachea ; cilia ; axonemes ; ciliary membranes ; biotin-streptavidin ; colloidal-gold ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cilia isolation methods were modified to retain respiratory tract ciliary membranes and to identify accessible surface components. Prior to isolation of cilia, halves of cow tracheae were treated with the extended spacer arm analog of N-hydroxy succinimido-biotin (NHS-LC-biotin) to label accessible membrane constituents. Mechanical disruption of the epithelium and substitution of CHAPS for Triton X-100 provided a good yield of cilia with membranes and with minimal contamination. Subsequent extraction of these cilia with Triton X-100 solubilized the membranes and released soluble matrix proteins. Proteins of membrane + matrix and axoneme fractions were analyzed after electrophoresis in sodium dodecyl sulfate polyacrylamide gels. The major biotin-labeled components in the membrane + matrix fraction were 105, 98, and 92 kd, were glycosylated, and remained with reconstituted, pelleted membrane vesicles along with the major non-biotinylated protein at 51 kd. Other membrane+matrix proteins at 126 and 76 kd bound streptavidin even from noniabeled trachea, but remained soluble. Several biotin-labeled proteins distinct from those in the membrane fraction remained with Triton X-100-extracted axonemes. Streptavidin-colloidal-gold (SAG) particles appeared to bind randomly along the length of cilia. The peripheral join between A and B microtubules was a predominant nonspecific location of SAG on axonemes. Axonemes with biotin label also bound significant numbers of SAG to outer dynein arms, confirming the streptavidin reaction with separated proteins on transfers. These results suggest close association of the membrane with the axoneme in respiratory tract cilia and a membrane composition somewhat different from protozoan cilia.
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  • 38
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    Cell Motility and the Cytoskeleton 17 (1990), S. 345-355 
    ISSN: 0886-1544
    Keywords: cell fusion ; polykaryon ; cytoskeleton ; F-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To study the involvement of the cytoskeletal system in the fusion of animal cells, we examined the dynamic changes of cytoskeletal proteins during the various stages of cell fusion. CV-l cells were fused by applying a radio-frequency electrical pulse. Structural changes of microtubules (MTs) and F-actin were monitored simultaneously by double-label fluorescence microscopy. It was observed that in a few minutes after the initiation of cell fusion, MT bundles began to extend into the cytoplasmic bridges which were formed by fusing the membranes of neighboring cells. Later, a network of parallel MT bundles appeared between the adjacent nuclei of the fusing cells; such MT bundles may provide the mechanical links that are responsible for nuclear aggregation. The structural changes of Factin during cell fusion were more complicated. We observed many different patterns of actin distribution in the fusing cells, including some giant, ring-shaped structures. Reorganization of actin is unlikely to be involved in the nuclear aggregation process. Instead, actin bundles condensed at the cell edges may help to widen the cytoplasmic bridges to allow merging of cellular contents between the fusing cells.
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  • 39
    ISSN: 0886-1544
    Keywords: cytoskeleton ; glycoconjugates ; axoneme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The photoreceptor connecting cilium bears a unique transmembrane assemblage which stably links cell surface glycoconjugates with the underlying axonemal cytoskeleton. Structural similarities between the photoreceptor connecting cilium and the transition zone of motile cilia suggests that this assemblage may also be present in motile cilia. Using a subcellular fraction enriched in detergent-extracted photoreceptor axonemes, three high molecular mass glycoconjugates (425, 600, and 700 kD) were previously identified as potential components of the assemblage. Through oligosaccharide characterization and binding of a specific monoclonal antibody, we have verified the localization of the 425 kD glycoconjugate to the transmembrane assemblage. Binding of the lectin peanut agglutinin (PNA) to the 425 kD glycoconjugate on nitrocellulose blots, and to isolated detergentextracted axonemes, was assessed following treatment with the enzymes neuraminidase and O-glycanase. Changes in binding to the 425 kD glycoconjugate precisely paralleled changes in binding to intact axonemes, supporting the hypothesis that the 425 kD glycoconjugate is a component of the transmembrane assemblage. Furthermore, the results suggest that the 425 kD glycoconjugate contains sialated galactose-N-acetylgalactosamine oligosaccharides which are Olinked to the protein backbone. To directly assess the distribution of the 425 kD glycoconjugate, we produced a monoclonal antibody directed against this glycoconjugate. The antibody, K26, recognizes only the 425 kD on transblots of the axoneme fraction. K26 immunoreactivity of intact axonemes is identical to that seen by PNA staining. K26 staining of isolated photoreceptors and whole retina is uniquely localized to the region of the connecting cilium. Thus, in the photoreceptor, the 425 kD is not only a component of the transmembrane assemblage but is also completely restricted to the connecting cilium.Based on morphological similarities, the photoreceptor connecting cilium is thought to be homologous to the transition zone of the motile cilium. As such, we have stained oviduct epithelium with the K26 monoclonal antibody. Immunoreactivity is restricted to the region of the transition zone at the base of motile cilia. This demonstrates that the photoreceptor connecting cilium and motile cilium transition zone are immunologically related.
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  • 40
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    Journal of Chemometrics 4 (1990), S. 195-216 
    ISSN: 0886-9383
    Keywords: Entropy ; Decrease of uncertainty ; Information gain ; Relevance coefficients ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Information theory makes it possible to judge and evaluate methods and results in chemical analysis. The obtained information can be expressed in different ways. One way is to define information as the decrease of uncertainity after analysis. Conditional probabilities are therefore considered when evaluating the information provided by qualitative analyses. However, the use of other information measures, such as the information gain, is often preferable. In multicomponent analysis the translation of information from signals to the amounts of the analytes has been investigated along with the relevance of individual components. Information theory can also be applied to find the optimum experimental conditions. The evaluation of the properties of analytical methods by information theory has been proposed.
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  • 41
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    Journal of Chemometrics 4 (1990), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 42
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    Journal of Chemometrics 4 (1990), S. 291-298 
    ISSN: 0886-9383
    Keywords: Deconvolution ; Jansson's method ; Peak restoration ; Iterative deconvolution ; Peak resolution ; Chromatographic deconvolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of a cross-correlation prefiltering technique to enhance the ability of Jansson's iterative deconvolution procedure to deconvolve extremely noisy chromatographic data is investigated. Test cases include peaks whose resolutions are as low as 0.35 and whose signal-to-noise ratios are as low as 1:1. Evaluation criteria include RMS error, relative peak error and peak area repeatability. For comparison purposes, relative peak area errors and peak area variances are also evaluated for noisy but well resolved peaks that have only been prefiltered with the cross-correlation filter. Jansson's method in conjunction with cross-correlation prefiltering is shown not only to resolve overlapped peaks but in some cases to improve their signal-to-noise ratios. The study also establishes some limits to the capabilities of Jansson's method will regard to adverse data conditions.
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  • 43
    ISSN: 0886-9383
    Keywords: Calibration ; Polynomial regression ; D-optimality ; Experimental design ; Model discrimination ; Lack of fit ; Least squares regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper a criterion is described for the construction of experimental designs for the evaluation of calibration models in analytical chemistry. The proposed criterion seeks a compromise between the D-optimal designs for estimating the parameters of different polynomial models. A computer algorithm is presented for a sequential construction of experimental designs using the optimality criterion. The performance of the optimality criterion and the computer algorithm is elaborated for the problem of discrimination between a first- to a third-degree polynomial for the calibration of analytical methods. An experimental design consisting of replicate measurements at five distinct levels equally spaced over the calibration range proved a good solution.
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  • 44
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 45
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    Journal of Chemometrics 4 (1990), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 46
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    Journal of Chemometrics 4 (1990), S. 271-289 
    ISSN: 0886-9383
    Keywords: Smoothing ; Digital filter ; Shot noise ; Signal processing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Digital filter smoothing methods for shot-noise-limited data are addressed in this study. The preferred method is based on a Gaussian filter in which the width of the Gaussian filter function is varied depending on the estimate of the second derivative of the raw data. This filter is developed from the standpoint of maximum likelihood parameter estimation of the probability density function which describes shot-noise-limited data. The smoothing filter is tested and compared with the conventional sequential regression filter. This adaptive Gaussian smoothing filter works better than both the sequential regression and the adaptive Gaussian filter derived for normal noise. For data containing both high- and low-frequency components, the limiting step in the adaptive filter is an estimation of the smoothing interval. Methods for determining an optimum smoothing interval are discussed. With the optimized smoothing interval, the adaptive Gaussian filter works well for data sets with a wide range of varying frequency components. In particular, synthetic data typical of atomic emission spectra are used to test this smoothing filter.
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  • 47
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    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 48
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    Journal of Chemometrics 4 (1990), S. 337-354 
    ISSN: 0886-9383
    Keywords: Chemometrics ; Chemometrics Society ; History of chemometrics ; Pioneers of modern chemometrics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This is a first foray into the historical start and early years of chemometrics from about 1972 onwards. We have gathered interviews with three originators (Kowalski, Wold and Massart) as well as with a selected group of six other well-known chemometricians who gradually became active in the 1970s (Christie, Clementi, Hopke, Martens, Brown and Deming). The interviews include amongst a host of subjective recollections a succinct record of the key historical literature as highlighted by the interviewees' own rankings of ‘earliest’ and ‘best’.A discussion of the most general commonalities in these interviews together with other historical material is presented in the second part of the paper.
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  • 49
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    Journal of Chemometrics 4 (1990), S. 355-360 
    ISSN: 0886-9383
    Keywords: Pattern recognition ; U.K. chemometrics usage ; Quantitative structure-activity relationships ; Artificial intelligence ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A survey of members of the U.K. QSAR Discussion Group has been made to determine the extent of use and development of chemometric and artificial intelligence (AI) methods in the analysis of multivariate quantitative structure-activity relationship (QSAR) data in the U.K. Chemometric methods were found to be well established in both industrial and educational establishments and there was significant method development occurring. AI methods were not employed to any great extent and the general level of interest in these techniques was low compared to chemometric methods. A requirement for more education in multivariate statistical methods and regression methods was indicated. A need for a user-friendly, comprehensive, commercially available multivariate statistical package containing multivariate stability testing and regression diagnostic methods was identified.
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  • 50
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    Journal of Chemometrics 4 (1990), S. 387-387 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 51
    ISSN: 0886-9383
    Keywords: PCA ; Essential oils ; Mandarine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mandarine essential oils are extracted from green unripened fruits as well as from red fruits at ripening, both oils having specific uses as natural additives in the food industry. Two processes of production, pressing and peeling, are currently adopted in their production. Capillary gas chromatography with flame ionization detection has been suggested as a sensitive method for the fractionation of volatile components of the essential oils. Principal component analysis was proposed as an exploratory chemometric method for the differentiation of essential oils from fruits at different degrees of ripening, taking into account the processes of production. Product-moment correlations between variables (concentrations of 17 components) were used as starting matrices and the explained variance was adopted as a criterion for eigenvalue selection. Bi-plots and three-dimensional plots of unrotated principal component scores were systematically used as well as those of orthogonally rotated factor scores. The 17 variables were reduced to four principal components, which explained 87% of the total variance. Projection on the first three eigenvectors of all data as unrotated component scores allowed for a tentative differentiation of 59 oils according to their degree of ripening. The two processes of production were also differentiated in a sample of 55 oils.
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  • 52
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    Journal of Chemometrics 4 (1990), S. 387-387 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 53
    ISSN: 0886-9383
    Keywords: Sample size ; Monte Carlo ; Multivariate, normal ; Q-Q plots ; Classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Because many pattern recognition techniques are predicated on the assumption of mutivariate normal data, Monte Carlo simulation studies were performed to determine the number of samples that are necessary to describe a multivariate normal population adequately. From these studies we have learned that hundreds of samples are required. These results suggest that parametric procedures should only be used to analyze very large data sets.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 54
    ISSN: 0886-9383
    Keywords: Principal components ; Multiple and stepwise regression ; Non-parametric density and regression estimation ; Bootstrap inference ; Canonical correlation ; PLS regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A statistical study of the dependence between various critical fusion temperatures of a certain kind of coal and its chemical components is carried out. As well as using classical dependence techniques (multiple, stepwise and PLS regression, principal components, canonical correlation, etc.) together with the corresponding inference on the parameters of interest, non-parametric regression and bootstrap inference are also performed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 55
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 56
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 255-266 
    ISSN: 0886-9383
    Keywords: Similarity measure ; Cluster analysis ; Riemannian space ; Metric tensor ; Curvature ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results of unsupervised pattern recognition methods are critically dependent on the measure of similarity used for clustering objects. There is little a priori information available on the relative utility of various similarity measures. We introduce here an alternative similarity measure based on the metric tensor measure (MTM). Two standard clustering strategies are tested with the proposed similarity measure: hierarchical clustering and the K-median method. As data we use the ARCH obsidian data, a data set on Hungarian coal, and trace element data on Hungarian paprika. Differences from the Mahalanobis distance measure are described for intraclass relations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 57
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 267-268 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 58
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 59
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 60
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0887-3585
    Keywords: simulated annealing ; computer-aided drug design ; substrate docking ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The Metropolis technique of conformation searching is combined with rapid energy evaluation using molecular affinity potentials to give an efficient procedure for docking substrates to macromolecules of known structure. The procedure works well on a number of crystallographic test systems, functionally reproducing the observed binding modes of several substrates.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 61
    ISSN: 0887-3585
    Keywords: RBP ; RBP family ; protein structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000