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  • 1
    Electronic Resource
    Electronic Resource
    Towards a new classification of intracellular particle movements based on quantitative analyses (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 128-135 
    Details
    ISSN: 0886-1544
    Keywords: motion analysis ; axonal transport ; cytoplasmic transport ; Brownian motion ; AVEC-DIC microscopy ; saltatory particle motion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey study of organelle movements in a variety of cell types of plant and animal origin was made with the aid of video-enhanced contrast, differential interference contrast (AVEC-DIC) microscopy followed by fine analysis of the motile behavior of the individual organelles. We found that there exists besides Brownian motion a wide spectrum of active motions in cells, i.e. motion that is directionally biased through the expenditure of metabolic energy. The types of active motion seen range from a continuous motion (sometimes appearing as streaming) in plant cells and neurons to various types of less ordered and less well directed motion. We did not see any clear-cut qualitative difference between plant and animal cells or between systems presumed to be actin- and microtubule-based. A preliminary classification of the types of active motion is presented. The ongoing research activities, which aim at a more precise definition of the different types of motion by a set of quantitative parameters, are described, and the progress made so far is reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060210
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  • 2
    Electronic Resource
    Electronic Resource
    Substructure of sidearms on squid axoplasmic vesicles and microtubules visualized by negative contrast electron microscopyPart of this work was performed at the Marine Biological Laboratory, Woods Hole, MA 02543. (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 20-30 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present a high-resolution electron microscopic study of the sidearms on microtubules and vesicles that are suggested to form the crossbridges which produce the microtubule-based vesicle transport in squid axoplasm. The sidearms were found attached to the surfaces of the anterogradely transported vesicles in the presence of ATP. These sidearms were made of one to three filaments of uniform diameter. Each filament measured 5-6 nm in width and 30-35 nm in length. The filaments in some of the sidearms had splayed apart by pivoting at their base, thereby assuming a “V” shape. The spread configuration illustrated the independence of the individual filaments. The filaments in other sidearms were closely spaced and oriented parallel to each other, a pattern called the compact configuration. In axoplasmic buffer containing AMP-PNP, structures indistinguishable from the filaments of the sidearms on the vesicles were observed attached to microtubules. Pairs of filaments, thought to represent the basic functional unit, were observed attached to adjacent protofilaments of the microtubules by their distal tips. These data support a model of vesicle movement in which a pair of filaments within a sidearm forms two crossbridges and moves a vesicle by “walking” along the protofilaments of the microtubule.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070104
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of vanadate on the assembly and disassembly of purified tubulin (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 314-323 
    Details
    ISSN: 0886-1544
    Keywords: vanadate ; microtubules ; tubulin polymerization ; taxol ; dynein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sodium-orthovanadate (100-700 μM) added to purified pig brain microtubule protein (molar ratios 13-90 moles vanadate/mole tubulin) inhibits to a considerable extent the assembly (up to 65%) and the disassembly rates (up to 60%) of microtubules, as determined by turbidimetry. Vanadate added to preformed microtubules did not appreciably alter the turbidity level of the samples, however, the disassembly rates were decreased in the same manner as when vanadate was added prior to polymerization. Microtubule protein kept on ice for 3-6 hours became more susceptible to vanadate than freshly prepared protein. The effect of vanadate was independent of the GTP concentration at which the polymerization assays were performed (0.025 to 1 mM GTP). In the presence of taxol, which increases the rate and extent of microtubule formation, vanadate had no effect on assembly rates. Disassembly was inhibited, however, much less than in the presence of vanadate alone. Electron microscopy and polyacrylamide gel electrophoresis did not reveal differences between microtubules prepared in the presence or in the absence of vanadate. This is consistent with the notion that vanadate does not interfere with the interaction between tubulin and the high-molecular weight microtubule-associated proteins. Apparently vanadate brings about an allosteric change of the microtubule protein(s) resulting in the abnormal polymerization kinetics of tubulin found in our study. The above results may be relevant for studies where the effects of vanadate on intracellular motility are interpreted as being solely due to a specific inhibition of ATPases.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060308
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  • 4
    Electronic Resource
    Electronic Resource
    Movement of axoplasmic organelles on actin filaments from skeletal muscle (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 28 (1994), S. 231-242 
    Details
    ISSN: 0886-1544
    Keywords: squid axoplasm ; organelle movement ; calmodulin ; actin filaments ; axonal transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It was recently shown that, in addition to the well-established microtubule-dependent mechanism, fast transport of organelles in squid giant axons also occurs in the presence of actin filaments [Kuznetsov et al., 1992, Nature 356:722-725]. The objectives of this study were to obtain direct evidence of axoplasmic organelle movement on actin filaments and to demonstrate that these organelles are able to move on skeletal muscle actin filaments. Organelles and actin filaments were visualized by video-enhanced contrast differential interference contrast (AVEC-DIC) microscopy and by video intensified fluorescence microscopy. Actin filaments, prepared by polymerization of monomeric actin purified from rabbit skeletal muscle, were stabilized with rhodamine-phalloidin and adsorbed to cover slips. When axoplasm was extruded on these cover slips in the buffer containing cytochalasin B that prevents the formation of endogenous axonal actin filaments, organelles were observed to move at the fast transport rate. Also, axoplasmic organelles were observed to move on bundles of actin filaments that were of sufficient thickness to be detected directly by AVEC-DIC microscopy. The range of average velocities of movement on the muscle actin filaments was not statistically different from that on axonal filaments. The level of motile activity (number of organelles moving/min/field) on the exogenous filaments was less than on endogenous filaments probably due to the entanglement of filaments on the cover slip surface. We also found that calmodulin (CaM) increased the level of motile activity of organelles on actin filaments. In addition, CaM stimulated the movement of elongated membranous organelles that appeared to be tubular elements of smooth endoplasmic reticulum or extensions of prelysosomes. These studies provide the first direct evidence that organelles from higher animal cells such as neurons move on biochemically defined actin filaments. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970280306
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamic instability and motile events of native microtubules from squid axoplasm (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 10 (1988), S. 285-295 
    Details
    ISSN: 0886-1544
    Keywords: organelle movement ; microtubule assembly/disassembly ; motion analysis ; MAPs ; force generation ; axonal transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Native microtubules from extruded axoplasm of squid giant axons were used as a paradigm to characterize the motion of organelles along free microtubules and to study the dynamics of microtubule length changes. The motion of large round organelles was visualized by AVEC-DIC microscopy and analyzed at a temporal resolution of 10 frames per second. The movements were smooth and showed no major changes in velocity or direction. During translocation, the organelles paused very rarely. Superimposed on the rather constant mean velocity was a velocity fluctuation, which indicated that the organelles are subject to considerable thermal motion during translocation. Evidence for a regular low-frequency oscillation was not found. The thermal motion was anisotropic such that axial motion was less restricted than lateral motion. We conclude that the crossbridge connecting the moving organelle to the microtubule has a flexible region that behaves like a hinge, which permits preferential movement in the direction parallel to the microtubule. The dynamic changes in length of native microtubules were studied at a temporal resolution of 1 Hz. About 98% of the native microtubules maintained their length (“stable” microtubules), while 2% showed phases of growing and/or shrinking typical for dynamic instability (“dynamic” microtubules). Gliding and organelle motion were not influenced by dynamic length changes. Transitions between growing and shrinking phases were low-frequency events (1-10 minutes per cycle). However, a new type of microtubule length fluctuation, which occurred at a high frequency (a few seconds per cycle), was detected. The length changes were in the 1-3 μm range. The latter events were very prominent at the (+) ends. It appears that the native axonal microtubules are much more stable than the purified microtubules and the microtubules of cultured cells that have been studied thus far. Potential mechanisms accounting for the three states of microtubule stability are discussed. These studies show that the native microtubules from squid giant axons are a very useful paradigm for studying microtubule-related motility events and microtubule dynamics.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970100133
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  • 6
    Electronic Resource
    Electronic Resource
    Multiple pathways are involved in protection of MCF-7 cells against death due to protein synthesis inhibition (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 163 (1995), S. 570-576 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previously we have shown that IGF-1 protected MCF-7 cells against death induced by the protein synthesis inhibitor cycloheximide (CHX). In the present study we investigated the ability of protein kinase C activator 12-0-tetradecanoyl-phorbol-13-acetate (TPA), the protein kinase A activator 8-bromoadenosine 3′5′-cyclic monophosphate (Br-cAMP), and the enzyme inhibitor aurintricarboxylic acid (ATA) to protect MCF-7 cells against death, due to a continuous presence of CHX. Cell death was evaluated after 48 h of incubation by several techniques (trypan blue staining, release of lactic dehydrogenase, cellular ATP content, transmission electron microscopy, and DNA fragmentation). Apoptosis which terminates in necrosis, characterized this mode of cell death. TPA and ATA at optimal concentrations of 40 ng/ml and 100 μg/ml, respectively, reduced cell death to the control level (without CHX), while Br-cAMP at an optimal concentration of 650 μg/ml reduced cell death only partially. IGF-1, TPA, and ATA, which stimulated protein synthesis in the control MCF-7 cells, had no effect on protein synthesis in the CHX-treated cells, indicating that the survival effect is not due to new protein synthesis. The protein kinase C inhibitor staurosporine blocked the survival effect of TPA and IGF-1 in a dose-dependent manner, however did not affect the survival effect of ATA. The tyrosine kinase inhibitor genistein blocked the survival effect of IGF-1, but not that of TPA and ATA. Our results provide evidence for several distinctive pathways, the activation of which protects MCF-7 cells against death, due to protein synthesis inhibition. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041630318
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  • 7
    Electronic Resource
    Electronic Resource
    Cytokines and growth factors modulate cell growth and insulin-like growth factor binding protein secretion by the human salivary cell line (HSG) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 165 (1995), S. 223-227 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The human salivary cell line (HSG) was investigated for the effect of various growth factors and cytokines on cellular proliferation and on the production of insulin-like growth factor binding proteins (IGFBPs). IGF-l increased cell growth by approximately 25%, and induced the appearances of three distinct protein bands on ligand blot of the cell culture. Two bands with molecular weights of 43 and 45. Kda, respectively, proved to be IGFBP-3 using a specific antibody, and the third was a 24 Kda species (probably, IGFBP-4). Similar IGFBPs were released by the cells following stimulation by EGF and insulin as well as following incubation with the IGF-I receptor antibody αIR3. Retinoic acid had an inhibitory effect (50%) on IGF-I-induced cellular proliferation and an attenuative effect on the 24 Kda band when it was combined with IGF-I, and to a lesser effect EGF; however, it enhanced IGFBP-3 production when incubated with IGF-I. The IGF-I receptor antibody had an agonistic effect on IGFBPs production when applied alone or together with IGF-I. TNF-α and INF-γ had minimal effects on cell growth when added alone but when applied in combination, a marked inhibition of cellular proliferation was noted. These cytokines caused increased accumulation of IGFBP-3, -4, and -5. Addition of IGF-I to these cytokines enhanced the expression of these bands. These data demonstrate that growth factors and cytokines which modulate HSG cell growth, induce specific IGFBPs which may play a role in their effects on cell growth. © 1995 Wiley-Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041650202
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  • 8
    Electronic Resource
    Electronic Resource
    Epididymal sperm profiles in young adult, middle-aged, and testosterone-supplemented old rats (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 19 (1988), S. 401-409 
    Details
    ISSN: 0148-7280
    Keywords: cyclodextrin ; reproduction ; gerontology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Both ejaculated semen and epididymal contents from an individual male contain sperm that differ in various physicochemical characteristics. An experiment is reported in which epididymides from rats 5-24 months old were subjected to density gradient centrifugation to separate gametes of different stages of maturity. The research was designed to examine typical changes in “profiles” of sperm maturity during the reproductive lifetime of rats. Also, testosterone complexed with cyclodextrin that mimics the episodic release of the endogenous hormone was used to supplement the decreased circulating titers of some of the old males. Results revealed clear ontogenetic patterns of gradually decreasing reproductive competence as measured by absolute numbers of sperm, circulating levels of testosterone, and various other physiological markers of fertility. Sperm profiles also revealed age-specific changes with a shift toward progressively more mature, perhaps senile, gametes that begins at middle age. Testosterone supplementation (400 μg/kg b.w./day for 30 days) failed to restore sperm numbers or other measures of physiology in the old males, but the steroid modified sperm profiles to approximate more closely the profiles characteristic of young adult males than either untreated middle-aged or old males. The data were interpreted as suggesting that epididymal sperm profiles clearly identify males of different ages, and that the aging epididymis retains its capacity to respond to manipulations that modify the endocrine milieu.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120190411
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  • 9
    Electronic Resource
    Electronic Resource
    Ion exposure chambers for small animals (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 7 (1986), S. 1-11 
    Details
    ISSN: 0197-8462
    Keywords: ion exposure chamber ; ion concentration ; current density ; electric field ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Ion exposure chambers that have been designed and tested for use in biological and behavioral research with small animals are described in this report. The chambers exhibit an acceptable degree of uniformity in ion concentration, current density, and electric field within the exposure area. Gaseous by-products of corona discharge (O3 and NO2) have been measured and found to be 〈 .01 ppm and 〈 .1 ppm, respectively. Filtered air is fed to the individual exposure chambers, and temperature and humidity are well controlled. Noise due to corona and the air delivery system has been measured.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250070102
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  • 10
    Electronic Resource
    Electronic Resource
    Inhalation chambers for air ion research (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 4 (1983), S. 167-180 
    Details
    ISSN: 0197-8462
    Keywords: air ions ; corona discharge inhalation system ; DC electric fields ; small animal exposure system ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Many previous problems in establishing the nature of biological and behavioral effects of small air ions have been due to poor control over the ion-inhalation microclimate, resulting in nonuniform electrical fields and highly uneven concentrations of small air ions. We have developed a corona discharge air ion-inhalation system for use with animals that incorporates rigorous control over the microclimate and produces highly uniform concentrations of small air ions throughout the exposure area.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250040207
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