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  • Inorganic Chemistry  (706)
  • Cell & Developmental Biology  (701)
  • 1980-1984  (1,407)
  • 1982  (1,407)
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  • 1980-1984  (1,407)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 273-285 
    ISSN: 0886-1544
    Keywords: actin gelation ; F-actin nucleation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new actin binding protein has been purified to homogeneity from amoebae of Dictyostelium discoideum. This protein is a single polypeptide with a molecular weight of 120,000 upon sodium dodecyl sulfate gel electrophoresis. It is soluble and trypsin-sensitive, contains no carbohydrate, increases the viscosity and sedimentation rate of F actin, and inhibits the actin-stimulated Mg ATPase of rabbit muscle heavy meromyosin. The interaction of 120,000-dalton protein with F actin is not inhibited by millimolar ATP, pyrophosphate, or micromolar calcium. The 120,000-dalton actin binding protein increases the initial rate of actin polymerization and decreases the critical concentration of actin at steady state.These properties demonstrate that 120,000-dalton protein from Dictyostelium discoidum is not a myosinlike protein. Rather, this protein is probably involved in regulating the assembly of the actin cytoskeletion.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 287-308 
    ISSN: 0886-1544
    Keywords: actin-binding protein ; Dictyostelium ; cytoskeleton ; amoeboid movement ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protein from Dictyostelium discoideum with an apparent subunit molecular weight of 95,000 daltons (95K protein) was previously identified as an actin-binding protein ‘Hellewell and Taylor, 1979’. In this paper, we present a method for purifying the protein, and characterize some important aspects of its structure and function. Purification of the 95K protein is achieved by fractionation with ammonium sulfate followed by chromatography on DEAE-cellulose, gel filtration on 6% agarose, and final purification on hydroxyapatite. The 95K protein is a dimer, composed of apparently identical subunits. It is a rod-shaped molecule, 38 nm in length, with a Stokes radius of 74 Å. In these structural properties, the 95K protein is similar to muscle and nonmuscle α-actinins. The 95K protein and filamin are equally competent, when compared on a weight basis, to enhance the apparent viscosity of actin as determined by falling ball viscometry. The apparent viscosity of mixtures of the 95K protein and actin is dramatically reduced at pH greater than 7.0 or free ‘Ca2+’ greater than 10-7 M. We also examine the mechanism by which calcium regulates the interaction of the 95K protein and actin. A change in free ‘Ca2+’ induces no detectable change in the quaternary structure of the 95K protein. Our experiments indicate that the 95K protein does not dramatically alter the length distribution of actin filaments in the presence of micromolar free ‘Ca2+’. A large fraction of the 95K protein cosediments with actin in the presence of low free ‘Ca2+’ (ca. 3 × 10-8M), but not in the presence of high free ‘Ca2+’ (ca. 4 × 10-6M). We conclude that increased free ‘Ca2+’ inhibits gelation of actin by the 95K protein by reducing the affinity of the 95K protein for actin. We propose that 95K protein is an important component of the cytoskeletal/contractile system in D. discoideum amoebae.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 317-332 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; platelets ; actin-binding protein ; actin ; myosin ; thrombin activation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When human blood platelets were immersed in an ice-cold solution containing 1% Triton ×-1200, 40 mM KCl, 10 mM EGTA, 10 mM imidazole-HCl, and 2 mM NaN3 pH 7.0, a flocculent precipitate appeared immediately in the tube. This precipitate was collected at 3,000g and SDS-polyacrylamide gel analysis showed it to consist mainly of actin, α-actinin, actin-binding protein (ABP), and varying amounts of myosin.Any modifications of this solution used to isolate the platelets' Triton-insoluble cytoskeleton caused profound changes in the nature of the cytoskeleton isolated. Increasing the KCl concentration resulted in a lower yield of cytoskeletal actin and ABP. Inclusion of EDTA in the solution resulted in an increased amount of myosin associated with the cytoskeleton, whereas including MgATP decreased the myosin yield.Experiments with the purified proteins showed that ABP and myosin can each protect the actin from depolymerizing when dialyzed into the Triton solubilization solution. In addition, it was found that when platelets were stimulated with thrombin for 2 min prior to the addition of the Triton solution, 3-4 times more myosin was associated with the cytoskeletal precipitate.The results suggest, therefore, that any variations in solution conditions used for isolating the cytoskeleton from resting platelets, which results in alterations in the amount of ABP, may have profound effects on the state of actin polymerization. Likewise, in thrombin-activated platelets, it is suggested that the increased association of myosin with the cytoskeleton results in a greater stabilization of the F-actin associated with the cytoskeleton. These factors must be considered when interpreting the results regarding the nature of actin transformations in the resting and activated platelet.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982) 
    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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  • 5
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 369-383 
    ISSN: 0886-1544
    Keywords: motility ; flagella ; cilia ; microtubules ; Gregarines ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male gametes of the parasitic protozoan, Lecudina tuzetae, have a motile flagellum with a “6 + O” ultrastructure ‘Schrével and Besse, 1975’. These gametes were isolated from the cysts in which they develop and were observed and photographed under a variety of conditions. The flagella beat continuously, without stopping and starting, with a beat period of about 2 sec. They can beat in solutions whose viscosities are greater than 0.5 Nsm-2 (l Nsm-2 = 103 cP). The waveform can be approximated by a series of helical arcs and interconnecting straight regions that travel from the base to the tip. The helical regions have a radius of curvature of 3.2 μm and subtend a final angle of 1.7 radians. The straight portions are 2.0 μm in length. There are two sets of opposing bends, but they do not originate in the same plane. The resulting waveform is an approximately helical coil, with a pitch of 9.8 μm, a pitch angle of 0.6 radian and a peak-to-peak amplitude of 2.3 μm. The sense of the coil is left handed. The axoneme twists during beating. The main differences between the movement of this flagellum and that of typical 9 + 2 flagella are a low beat frequency and three-dimensional bends that produce relatively little forward movement of the cell. Twisting is discussed as a means of discriminating between some types of models of flagellar motility.
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  • 6
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 393-403 
    ISSN: 0886-1544
    Keywords: motility ; Ca2+ ; ionophores ; spirulina subsalsa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility of the marine filamentous cyanobacterium Spirulina subsalsa is both Ca2+ and Na+ dependent, and replacement of Na+ by mannitol arrests it. The data presented suggest that Ca2+ interacts with sites on the surface of the cell membrane. The inhibitory effect of dicyclohexylcarbodiimide (DCCD) hints at the possibility that the role of Ca2+ may be associated with a membrane bound Ca-ATPase. Motility is pH dependent, being nil at pH 〈 6.5 and 〉 10.0, with an optimum at 8.5. Norepinephrine abolishes most of the inhibitory effect of low pH on motility. Ca2+ has an “all-or-none” effect on motility that is triggered at 5 mM. Acetylcholine lowers the threshold of Ca2+ necessary for triggering motility.
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  • 7
    Electronic Resource
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    Cell Motility and the Cytoskeleton 2 (1982), S. 445-455 
    ISSN: 0886-1544
    Keywords: clot structure ; platelet contractility ; protein networks ; rheological techniques ; viscoelasticity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When citrated plasma is recalcified, it forms a viscoelastic gel-a clot. The relationship between platelet contractility and clot rigidity was studied by using a rheological technique which simultaneously measured both the dynamic rigidity modulus and the contractile force during gel formation with platelet rich plasma (PRP). Protein network formation in a clot was accompanied by a contractile force throughout the clotting process. PRP demonstrated a maximum elastic modulus of 6,000 dynes/cm2 and a maximum contractile force/area of 1,500 dynes/cm2. The values of these parameters for a platelet-free clot (PFP) were 700 dynes/cm2 and less than 100 dynes/cm2 respectively. Sonicated control PRP and PRP from a Glanzmann thrombasthenia patient both clotted in a manner similar to PFP. Metabolic inhibitors, 2-deoxy-D-glucose and KCN (5 mM each), retarded the clotting curves of PRP. Cytochalasin B and E suppressed both structural rigidity and force generation in a concentration-dependent manner similar to their inhibitory effect on actin polymerization in platelets. Colchicine (2.5 mM) or vinblastine (0.11 mM) did not affect these clotting curves. Thrombi-activated, fixed platelets did not generate any force, nor did they significantly increase clot rigidity. Streptokinase induced a concurrent decrease of both rigidity and force in PRP clots. The elastic modulus of a PFP clot could be increased to 2,500 dynes/cm2 by externally straining the network with an axial force/area of 1,500 dynes/cm2. Our results indicate that clot structure formation in PRP is strongly coupled to the contractile force generated by the platelet microfilament system and that this force modulates clot rigidity.
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  • 8
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 457-470 
    ISSN: 0886-1544
    Keywords: fragmin ; critical actin concentration ; nucleation ; filament growth ; pointed end ; barbed end ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As reported previously, fragmin isolated form Physarum plasmodia restricts the polymerization of actin to produce short F-actin filaments in the presence of Ca2+ ions. Here it is shown that when actin is polymerized at low concentrations of salts, fragmin increases the critical concentration of actin for polymerization. This effect of fragmin on the critical concentration is independent of the molar ratio of fragmin to actin. The addition of actin monomers onto heavy meromyosin-decorated F-actin fragments treated with fragmin occurs unidirectionally at the pointed end of each fragment. These results suggest that fragmin binds to the barbed ends of F-actin filaments and inhibits association and dissociation of actin monomers at this end. Fragmin accelerates the initial stage of polymerization of actin. When a constant amount of G-actin is polymerized in the presence of small amounts of fragmin, the inverse of the half-polymerization time increases in proportion to the square root of the amount of fragmin added. This means that fragmin acts as a potent promoter of the nucleation step in actin polymerization. Both functions of fragmin-promotion of nucleation and capping at the barbed end of F-actin-require micromolar concentrations of Ca2+.
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  • 9
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 471-482 
    ISSN: 0886-1544
    Keywords: calmodulin ; myosin ; antibody ; immunofluorescence ; amoeba ; Dictyostelium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A rabbit antiserum was raised against calmodulin from the eukaryotic microorganism Dictyostelium discoideum. In double immunodiffusion experiments, the antiserum formed an immunoprecipitation line with Dictyostelium calmodulin but not bovine brain calmodulin; competition radioimmunoassays showed no cross reactivity between the antiserum and calmodulins from bovine brain and spinach. The calmodulin content of vegetative Dictyostelium amoebae, determined by competition radioimmunoassay, was 0.5 μg/mg protein; similar levels were found in developing cells. The antiserum was used to visualize the distribution of calmodulin in Dictyostelium amoebae by indirect immunofluorescence. Cells were examined under various conditions: in suspension, attached to a substrate, and while phagocytosing yeast cells. In all cases, anticalmodulin staining was concentrated in the cell cortex. Parallel experiments using a monoclonal antibody against Dictyostelium myosin showed that this protein is also enriched in the cortical region of the cell.
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  • 10
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 355-367 
    ISSN: 0886-1544
    Keywords: proacrosome migration ; nuclear pore redistribution ; nuclear membrane fluidity ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microscopic examination of thin sections and freeze fractures of Locusta spermatids revealed that the proacrosome docks to the nuclear membrane and glides around the nucleus during sperm development. Whereas nuclear pore complexes occur in groups distributed at random over the entire nucleus of the early spermatid, they are found only in a narrow ring closely surrounding the centriolar adjunct in later spermatids. The pores appear to be swept caudally in the nuclear envelope, perhaps by a process like capping; they are not merely excluded by structures adhering to the nucleus. The observations suggest that both proacrosome migration and the deployment of pores are facilitated by the inherent fluidity of the nuclear membranes.
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  • 11
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 343-354 
    ISSN: 0886-1544
    Keywords: NBD-phallacidin ; actin ; ocular tissues ; wound repair ; stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fluorescent derivative of the actin-binding toxin phallacidin, 7-nitrobenz-2-oxa-1,3 diazole phallacidin, has been used to cytologically demonstrate the presence of actin in lens epithelium, corneal endothelium, and retinal pigment epithelium. In these noninjured tissues, no stress fibers are observed and fluorescence is confined mainly to an area at or near the cell membrane, although some diffuse cytoplasmic staining can also be seen. However, following injury to either the lens epithelium or corneal endothelium of rats and frogs, stress fibers are detected, but only in those cells that migrate into the wound area. Cells on the periphery of each tissue do not partake in would repair and thus maintain their normal appearance. After the tissue has regenerated, stress fibers disappear, and those cells involved in the injury response return to their normal morphology.When rabbit corneal endothelium is placed in tissue culture, stress fibers are observed as the cells migrate away from the initial explant. Upon reaching confluency, these cells spread out and each is surrounded by thick actin-containing bands. Furthermore, they exhibit some stress cables within their cytoplasm. This is in contrast to their appearance in vivo where stress fibers are absent and fluorescence is limited to a region near the cell membrane.
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  • 12
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 385-391 
    ISSN: 0886-1544
    Keywords: ciliated cell ; basal body apparatus ; microtubules ; microfilaments ; respiratory epithelium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This is a descriptive study showing the three-dimensional interrelationship of cytoskeletal elements at the apex of ciliated cells of rat respiratory epithelium. Tissue specimens were serially thin sectioned in various planes and examined by transmission electron microscopy. Thicker sections were also cut at various angles and analyzed stereoscopically. Other specimens were cleared of soluble molecules by glycerination or Triton-X 100 treatment and sectioned as described above. It was found that C microtubules from the triplets of each basal body diverge from the A and B microtubules, run a short distance, and converge at the basal foot. These microtubules or other microtubules arising anew then dispersed deeper into the cytoplasm. The C fibers also interdigitated with other microtubules running perpendicular to them and parallel to the ciliated surface. Ten-nanometer intermediate filaments were organized in parallel sheets between adjacent basal bodies. Sixnanometer actin filaments were distributed throughout the apical cytoplasm. Neighboring basal bodies were linked to one another by microtubules and microfilaments. Basal bodies from each cell appear to be structured for stability, flexibility, and arranged to operate as a single unit.
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  • 13
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 429-443 
    ISSN: 0886-1544
    Keywords: 21S dynein ; tubulin ; binding stoichiometry ; ATP sensitivity ; binding cooperativity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The binding properties of Tetrahymena 21S dynein to doublet A and B subfiber microtubules were analyzed by both a turbidimetric assay (Δ A350 nm) and electron microscopy. KCl-extracted, sucrose-gradient, purified 21S dynein binds to each of the two kinds of axonemal microtubules in both ATP-insensitive and ATP-sensitive modes, even though only a single type of binding occurs to each of the subfibers in situ. Total dynein bound to axonemal microtubules is a composite of binding that is sensitive to dissociation by ATP and binding that is insensitive to ATP. Each exhibits a different binding profile. Total binding exhibits a sigmoid profile (h = 1.93) and saturates at 1.49 mg D/mg T. ATP-sensitive binding likewise exhibits a sigmoid profile (h = 2.66) but saturates at 1.06 mg D/mg T. Binding occurs with a similar affinity for both A and B subfibers. The Hill coefficient (h) for ATP-sensitive binding implies positive cooperativity between binding events. ATP-insensitive binding was studied independently in 20 μM ATP, 10 μM vanadate, which blocks ATP-sensitive binding. ATP-insensitive binding exhibits a hyperbolic profile (h = 1.0) and likewise occurs along each of the two kinds of axonemal tubules. Binding saturates at 0.87 mg D/mg T. The binding data suggest that the tubulin dimer has conserved both ATP-sensitive and ATP-insensitive binding sites for 21S dynein, even though the sites may not be expressed in vivo.
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  • 14
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982) 
    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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  • 15
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. i 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 16
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    Cell Motility and the Cytoskeleton 2 (1982), S. 573-582 
    ISSN: 0886-1544
    Keywords: Euglena flagella ; laser microsurgery ; stigma ; Mg2+ ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When the area of the stigma of Euglena was irradiated with an infrared laser beam at a dose too low to cause permanent loss of motility, a reduction in flagellar motility was observed only when the external medium contained less than 1 mM Mg2+. At these low Mg2+ concentrations, the laser caused a decrease in flagellar frequency and a tendency for the flagellar waveform to shift towards that taken during reversed swimming. This suggests that the effect of the laser irrdiation was to deplete the cells of Mg2+. After the laser pulse the reversal response remained sensitive to the wavelength of the illuminating light. In white light (420-700 nm) 60% of the Euglena showed a reversed waveform; in orange light (530-700 nm) this increased to 90%. This shows that the photoreceptor was not destroyed by the laser irradiation.These experiments were performed on cells that had been impaled on a microelectrode. If direct electric current was passed into the laser-irradiated cells, the current necessary to cause flagellar arrest was 2 to 4 times less than that for cells not laser irradiated.It is concluded that an internal Mg2+ store is present in the Euglena, localized in the area of the paraflagellar swelling; and that the laser irradiation eliminates this Mg2+ store, but at the power used it does not destroy the ability of the stigmaparaflagella to control the flagellar activity.
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  • 17
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    Cell Motility and the Cytoskeleton 2 (1982), S. 599-614 
    ISSN: 0886-1544
    Keywords: monoclonal antibodies to tubulin ; radioimmune assay ; immunoautoradiography ; Western blots ; immunofluorescence ; tubulin heterogeneity ; eukaryotic flagellar motility ; immunomotility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two monoclonal antibodies reactive for α-tubulin but not for β-tubulin have been prepared, characterized in terms of their relative binding to tubulins from differnt sources by a solid-phase binding assay, immunoautoradiography, and indirect immunofluorescence, and utilized to study flagellar motility. Our results demonstrate that α-tubulins from different species, and even from different tissues of the same species, are nonidentical. Especially interesting was the observation that one of the antibodies, Ab2, immunofluorescently stained microtubules of chick embryo fibroblast cells, but was completely unreactive for microtubules of rat kangaroo (PtK2) fibroblasts; a different antibody, Ab1, stained both cell types. Results of these and additional experiments clearly show that Ab1 and Ab2 recognize discrete and different epitopes on α-tubulin.Monoclonal antitubulins Ab1 and Ab2 each inhibited the bend amplitude of reactivated sea urchin spermatozoa without affecting beat frequencies or the ability of the outer doublet microtubules to slide past each other in elastase-digested models. These results, together with those obtained previously using rabbit polyclonal antitubulin antibodies [Asai and Brokaw, 1980], demonstrate that inhibition of bend amplitude is a common property of antitubulin antibodies and is not due to the binding of antibodies to one specific site on the axoneme. Our results suggest that tubulin subunit conformational changes may occur on the outer doublet lattice and may be integrally involved in the mechanism and control of flagellar bending.
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  • 18
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    Cell Motility and the Cytoskeleton 2 (1982), S. 19-24 
    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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  • 19
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    Cell Motility and the Cytoskeleton 2 (1982) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 20
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    Cell Motility and the Cytoskeleton 2 (1982), S. 1-8 
    ISSN: 0886-1544
    Keywords: microfilaments ; F-actin ; brain actin-depolymerizing factor ; tropomyosin stabilization of microfilaments ; DNase I inhibition assay ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Brain or muscle F-actin is rapidly depolymerized to monomeric actin in vitro by actin-depolymerizing factor, a protein isolated from chick embryo brain. Binding of muscle tropomyosin to muscle F-actin protects the F-actin from depolymerization by this factor. A 8.4/1.0 molar ratio of actin subunits to tropomyosin, achieved by incubation of the F-actin with excess tropomyosin, protects 58% of the F-actin from depolymerization by excess actin-depolymerizing factor for at least 3 hr at 25°C. Thus, actin-depolymerizing factor seems to be specifically directed toward actin filaments lacking tropomyosin.
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  • 21
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    Cell Motility and the Cytoskeleton 2 (1982), S. 9-24 
    ISSN: 0886-1544
    Keywords: amoebae ; actinopoda ; heliozoa ; Actinophrys ; phagocytosis ; pseudopodia ; membrane ; extrusomes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two phases of prey capture by the heliozoon Actinophrys sol are documented by electron microscopy. The phases are those of prey adhesion to the predator and enclosure of the prey by the predator. Adherence is brought about by numerous small pieces of adhesive membrane produced by the predator at the site of prey contact. Some of the heliozoan extrusomes expel their contents at this time, but the significance of this event is unclear. Enclosure of the prey is effected by a funnelshaped pseudopodium. This is drawn over the prey by the action of the leading margin. The ultrastructural appearance of the cytoplasm of the leading margin differs from the rest of the cell, being homogeneous and finely filamentous. Both force and traction for the progression of the pseudopod are generated primarily at the tip. During the development of the funnel-pseudopod, extrusomes expand and fuse with each other and with the plasma membrane. Their investing membrane is thereby made available as food vacuole membrane.
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  • 22
    ISSN: 0886-1544
    Keywords: cell migration ; epithelial cell culture ; 2-deoxyglucose ; glycolysis ; microtrabecular lattice ; ATP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using a line of epithelial cells (SCCA5) derived from a spontaneous rat carcinoma, the glucose analogue 2-deoxyglucose (2DG) has been shown by time-lapse cinemicrography to produce a cessation of motility by 1 hour that can be reversed by replacement of the 2DG, and does not occur in equivalent media with or without glucose or in 2DG-containing media with added pyruvate and citrate. The effect on the cells at the edge of an epithelial island is to prevent the formation of new lamellipodia and produce a progressive retraction and condensation of lamellipodia already present. This effect of 2DG on motility corresponds with a significant reduction in the level of ATP that is partially restored after 30 minutes in the recovery incubation. Only a slight reduction in protein synthesis occurs in the presence of 2DG. The external morphology and the cytoplasmic ground substance of the cells were studied by scanning electron microscopy and high voltage electron microscopy respectively. It was found that after incubation in 2DG for 1 hour the outline of the free edges of the cells was distorted resulting in redistribution of microvilli, condensation of cytoplasm into strands, and irregular projections from the edges of residual lamellipodia. The structure of the cytoplasmic ground substance in lamellipodia from cells incubated in 2DG for 3 hours was distinctly different from that in cells incubated for 3 hours in 2DG then recovered for 25 minutes, or in cells incubated in glucose-containing medium for 3 hours. In the 2DG-treated cells the lattice-like structure evident in critical-point-dried cells was condensed into short thick strands that terminated in bulbous ends, whereas in cells recovered for 25 minutes the lattice material was elongated and tapering and the interlattice space relatively expanded. The results obtained support the concept of modulation occuring in the structure of the microtrabecular lattice component of the cytoplasmic ground substance coincident with alterations in cell function and metabolic state.
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  • 23
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    Cell Motility and the Cytoskeleton 2 (1982), S. 497-508 
    ISSN: 0886-1544
    Keywords: cilia ; electric motor control ; ciliates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied the motor responses to membrane hyperpolarization of the marginal cirri in Stylonychia using voltage-clamp, high-speed cinematography, and computer-processing techniques. The cirri started beating when voltage step amplitudes rose beyond 5 mV. The power stroke was oriented toward the posterior cell and (hyperpolarizing motor activation). The frequency rose slightly during a voltage step, and decreased with similar rates for 100 ms following the step end. Amplitude and duration of the step tended to increase the motor response of the cirri. The late response declined exponentially. The time constant of the decay rose with the step amplitude. Among three response parameters tested (frequency, duration, number of cycles), the number of evoked ciliary cycles was best correlated with the amplitude of the hyperpolarization. Comparisons with the responses to depolarizing voltage steps reveal similarities in the relaxation of ciliary activity which appears to be uncoupled, in part, from the electric membrane events during the voltage stimulus.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 583-597 
    ISSN: 0886-1544
    Keywords: endocytic vesicles ; microtubules ; 10-nm filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ligand binding to cell surface receptors induces rapid internalization of ligandreceptor complexes by receptor mediated endocytosis. We have examined the intracellular movement of endocytic vesicles, induced by the lectin concanavalin A (Con A), in cultured rat ovarian granulosa cells using fluorescence and electron microscopy. Within 20 minutes of ligand treatment at 37°C, numerous Con A-containing endocytic vesicles form, which migrate to the cell center by 60 minutes. Double label fluorescence microscopy, using fluorescien-Con-A and rhodamine immunofluorescent staining of tubulin or vimentin, indicates that during vesicle migration microtubules and 10-nm filaments are altered in their organization. By 30 minutes, vesicles are associated with microtubule bundles, which subsequently collapse around the nucleus. Similarly, 10-nm filaments accumulate around the nucleus in conjunction with the perinuclear aggregation of endocytic vesicles. Electron microscopy of Con A-horseradish peroxidase-labeled cells demonstrates that endocytic vesicles fuse to form large receptosome-like structures during intracellular migration and these structures are associated with cytoplasmic microtubules and 10-nm filaments. Taxol, a drug that stabilizes microtubules, prevents endocytic vesicle translocation to the Golgi region. Nocodazole, which causes microtubule disassembly, results in the collapse of 10-nm filaments and the central aggregation of endocytic vesicles. The data indicate that the cytoskeleton participates in the directed intracellular movement of endocytic vesicles; the possible subcellular basis for this movement is discussed.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 13-18 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 59-65 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 83-89 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 93-101 
    ISSN: 0886-1544
    Keywords: cell motility ; singlet microtubules ; dynein ; coccid insect ; aflagellate spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this report we demonstrate that in the coccid insects Pseudococcus, Phenacoccus, and Planococcus the whole spermatozoon is made up by a nuclear central core surrounded by two complete and one incomplete turns of concentric microtubule palisades. Microtubules of the outer row are linked by a system of short projections 6 nm long; those of the inner row are linked to each other by similar arms; a second system of 6 nm arms links the tubules of each inner row to those of the respective outer row. All these systems of arms are longitudinally spaced every ∼ 12 nm. The motility of this spermatozoon is due to waves progressing from the posterior extremity to the anterior one. By SDS polyacrylamide gel electrophoresis a group of high molecular weight polypeptides is detected, one of which migrates in coincidence with the A dynein band from sea urchin sperm. Our data suggest that occurrence in coccid spermatozoon of a motility due to singlet tubules-dynein interaction.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 73-82 
    ISSN: 0886-1544
    Keywords: desmids ; videomicrography ; photokinesis ; photophobic response ; photophosphorylation ; photosynthesis ; phototaxis ; uncouplers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of the uncouplers CCCP and DNP on photokinesis, phototaxis, and the photophobic response in the desmid Cosmarium have been studied both in population systems and by videomicrographic, single-cell analysis. Light-dependent motility is specifically inhibited by both uncouplers, indicating that photokinesis is driven by photophosphorylation. In population experiments, phototaxis and accumulations in light traps due to photophobic responses are inhibited by drug concentrations comparable to those that inhibit photokinesis. Analysis of single-cell behavior demonstrated, however, that neither photophobic responses elicited by an increase in light intensity (step-up response) nor by a decrease (stepdown response) are inhibited, as long as the reduced motility allows the organisms to cross a light--dark border. Phototactic orientation is not impaired by DNP in the single cell analysis, but CCCP significantly reduced the degree of orientation. The results indicate that, although chlorophyll is the photoreceptor for all three photoresponses, at least the photophobic response is independent of both the photosynthetic electron transport chain and photophosphorylation.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 103-113 
    ISSN: 0886-1544
    Keywords: actin ; cleavage ; fluorescein-labeled phalloidin ; microinjection ; phalloidin ; sand dollar eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Effects of microinjection of phalloidin on fertilization and cleavage of sand dollar (Clypeaster japonicus and Scaphechinus mirabilis) eggs were studied. The drug, previously injected into unfertilized eggs, showed no effect on the elevation of the fertilization membrane upon insemination up to an intracellular concentration of 50 μM. However, the movement of the egg pronucleus to the sperm pronucleus was inhibited and the fusion of pronuclei did not occur. The subsequent development no longer took place. When phalloidin was injected into fertilized eggs, the thickness of the cortical layer increased and the microvilli became conspicuous. Both nuclear division and cleavage were inhibited at the intracellular concentration of more than 20 μM, though the latter seemed to be more sensitive to phalloidin than the former.Fluorescein-labeled phalloidin (FL-phalloidin) was injected into eggs in order to investigate F-actin localization by fluorescence microscopy. In both unfertilized and fertilized eggs, FL-phalloidin was localized in the cortical layer within 1 min after injection. It was also localized in the cortical layer as radially oriented rodlike structures when injected into fertilized eggs before the disappearance of the nuclear membrane. No distinct fluorescence was detected in the mitotic apparatus or in the cleavage furrow. FL-phalloidin redistributed gradually into egg cytoplasm. In unfertilized eggs, fluorescent rods were found especially in the egg pronucleus 30 min after injection.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 183-195 
    ISSN: 0886-1544
    Keywords: crane flies ; meiosis ; spermatocytes ; chromosome movement ; nuclear envelope ; prophase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Meiotic prophase in spermatocytes of the crane fly, Nephrotoma suturalis, involves both the condensation and the movement of bivalent chromosomes. Since crane flies have only four bivalents that appear highly condensed during late prophase, changes of position and orientation of those bivalents relative to one another can be seen easily in living cells. Chromosome movement during the final 1 to 2 hr of diakinesis was analyzed in detail. Maximal velocities of prophase movements were between 0.1 and 1 μM/min. Metakinetic movements during prometaphase have similar velocities. To assess the physiological basis of prophase movements, experiments employing cyanide and cold treatment were performed. Prophase movements were abolished completely by cyanide, and, for the most part, the velocities of chromosomes in the cold at 2°C and 6°C were less than that of untreated cells at 22°C. The results suggest that prophase movements are energy dependent and may involve an enzyme-catalyzed process occurring in close association with the nuclear envelope.
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    Cell Motility and the Cytoskeleton 2 (1982) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 257-272 
    ISSN: 0886-1544
    Keywords: cellular slime mold ; microtubule-organizing centers ; tubulin ; microtubules ; polymerization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Nucleus associated bodies (NABs) were isolated from Dictyostelium discoideum or Dictyostelium mucoroides and their ability to nucleate microtubules in vitro was examined.NABs were localized at the tapered ends of the nuclei and released from lysed cells in complex with the nuclei. Microtubules radiating from the NAB could also be isolated with the complex under microtubule stabilizing conditions. The ultrastructure of the isolated NAB showed it to be composed of a core structure surrounded by an amorphous matrix.The ability of isolated NABs to nucleate microtubules in vitro was demonstrated by incubation with exogenous brain microtubule protein. Microtubule assembly was easily visualized by dark-field or immunofluorescence microscopy. Polymerization of microtubules seemed to be initiated not from the core structure but from the surrounding matrix.The number of microtubules polymerized from the NAB was directly counted in whole-mount preparations by electron microscopy, which provided a quantitative assay for the NAB activity. The nucleating activity of NAB was quite unstable and its half-life was calculated as about 5 hours. The activity was sensitive to protease digestion and was also temperature sensitive but could be stabilized by addition of glycerol or storage at - 80°C or in liquid nitrogen. These characteristics are analogous to those of the centrosomes in cultured mammalian cells and a possible explanation of their similarity is discussed.
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    Cell Motility and the Cytoskeleton 2 (1982) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 225-242 
    ISSN: 0886-1544
    Keywords: spermatozoa ; calcium ion transport ; motility regulation ; cholinergic agonists ; ouabain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Behavioral responses of mature spermatozoa treated with neurotropic factors suggest that calcium entry and intracellular transport may be regulated by a cholinergic mediated program. To test the validity of this proposed mechanism, the effect of several agents on Ca distribution in the sperm cell was examined cytochemically.Sites of Ca accumulation were visualized in thin sections of bull spermatozoa by the application of a modification of Gomori's histochemical procedure for phosphatases. Intact bull sperm cells incubated at room temperature in a buffered balanced salt solution containing 5 mM/liter of CaCl2 showed small, randomly scattered deposits of the reaction product. Similarly treated sperm cells, plasmolyzed in hypoosmotic KCl, revealed a greatly increased amount of deposit associated with the cell membranes (mitochondrial surfaces and plasmalemma), the axonemal complex components, and satellite fibers adjacent to the outer dense fibers. Preincubation of intact cells in nicotine or eserine considerably enhanced the entry of calcium into the cell and its association with the membranes and other intracellular organelles. Decamethonium, an irreversible depolarizer and blocker of cholinergic receptors, interfered with the uptake and intracellular distribution of the calcium. Ouabain, the digitalis glycoside that decreases progressive motility of bull sperm and inhibits Na-, K-ATPase, appears to block Ca efflux, causing an intense accumulation of electron-opaque particles in the plasma membrane while smaller numbers of particles are distributed sparsely throughout the cell interior.The cytochemical results showing enhanced calcium entry in the presence of cholinergic agents, depressed intracellular calcium in cells treated with cholinergic receptor blocker, and intense accumulation of calcium within the cell membrane in the presence of ouabain are consistent with spermatozoan behavioral responses to these agents. These observations support the concept that neurotropic factors may be involved in regulating transmembrane and intracellular transport of ions in control of sperm cell function.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 41-45 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 71-75 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 87-93 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 133-136 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 149-152 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 169-173 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 159-164 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 181-184 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 199-204 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 225-228 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 35-39 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 195-198 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 217-224 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 47-71 
    ISSN: 0886-1544
    Keywords: microtubules ; transport ; secretion ; peritrich ciliate ; directional turnover ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of microtubules in secretory granule translocation was studied during stalk secretion in the peritrich ciliate, Zoothamnium arbuscula. In each cell, the release of stalk-forming secretory materials is restricted to a specialized region of the cytoplasm, the scopula. Many of the membrane-bound secretory granules that dominate the scopular cytoplasm appear to be aligned along cortical microtubules that converge on the scopular surface. This arrangement is consistent with the hypothesis that microtubules transport granules relative to the sites of exocytosis. To establish the role of microtubules in stalk secretion, telotrochs were exposed to agents with different disruptive effects on microtubule function. Exocytosis itself is not prevented by these drugs, and granules positioned for secretion prior to treatment are released. Maytansine and isopropyl-n-phenyl carbamate (IPC) completely inhibit stalk elongation. In maytansine-treated cells, microtubules are absent from the scopular cytoplasm, and granules are absent from the scopular surface. Microtubules are present in IPC-treated cells, but the granules are misdirected to the cytoplasm lateral to the scopula where no secretory sites exist. Even though the rate of stalk secretion is decreased by deuterium oxide (D2O), a control length stalk is eventually produced. In D2O-treated cells microtubules are present and in their normal orientation. The inhibition of secretion when microtubules are absent (maytansine) or misdirected (IPC) and the retardation of secretion when microtubule turnover is reduced (D2O) supports a mechanism of granule transport based on the directional turnover of microtubule subunits.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 131-147 
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    Keywords: higher land plant contractile system ; actin activation of myosin ; S-1 decoration of actin ; polymerization of actin ; calcium sensitivity of actomyosin interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper describes the initial isolation of actin- and myosin-like proteins from the cytoplasm of the endocarp tissue cells of the fruit of the tomato, Lycopersicon esculentum. Low ionic strength buffers extracted the 42,000 molecular weight tomato actin in the depolymerized form. Tomato actin can be polymerized in 0.1 M KCl, 2 mM MgCl2 to form 6 nm diameter filaments resembling rabbit skeletal muscle F-actin in their ultrastructure and pattern of decoration with rabbit myosin subfragment-1 (S-1). Tomato F-actin activates the low ionic strength Mg2+ ATPase of rabbit S-1 up to ten-fold. High ionic strength extracts of tomato yield a myosinlike enzyme whose ATPase activity in 0.5 M KCl is maximal in the presence of K+-EDTA and is repressed in the presence of Mg2+. The column-purified enzyme forms a complex with rabbit F-actin, which can be dissociated by Mg2+ ATP. The low ionic strength Mg2+ ATPase of tomato myosin can be activated ten-fold by rabbit actin and up to nineteen-fold by tomato actin. No activation of the tomato myosin by rabbit F-actin occurs in the absence of free calcium ions.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 149-161 
    ISSN: 0886-1544
    Keywords: cell locomotion ; gastrulation ; contact paralysis ; collagen substratum ; serum factors ; morphogenetic movements ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Prospective mesodermal cells of Xenopus laevis gastrulae showed substantial locomotion in vitro, averaging 4.3 μM/min, when dissociated and cultured on a glass surface coated with collagen and fetal bovine serum. The cell translocate by making lamellipodia and filopodia whereas the main cell body remains rounded. When two mesodermal cells made contact with each other, they showed contact paralysis of lamellipodial activity. In contrast, when mesodermal cells contact ectodermal cells, contact paralysis does not occur. Rather, migrating mesodermal cells continue to translocate. The locomotion in vitro appears to mimic that in vivo during gastrulation, because of the similarities of the rate of movement and the cell shape in culture and in embryos. Neither prospective ectodermal cells from gastrulae nor prospective mesodermal cells from blastulae showed locomotion under the same culture conditions.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 163-171 
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    Keywords: concanavalin A ; platelet ; lamella ; pseudopod ; lectin receptor ; cytochalasins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ligand-induced redistribution of concanavalin A (Con A) receptors on the surfaces of substrate-spread rabbit platelets was studied. These receptors were diffusely distributed on the surface of prefixed cells. Incubation of living cells with Con A and anti-Con A antiserum led to redistribution of corresponding receptors: These receptors were patched, removed from the upper surface of substrate-attached pseudopodia and lamellipodia, and accumulated on the surface of central cell parts. Capping of receptors was inhibited by cytochalasins B and D and by cold. Thus, capping of surface receptors can take place not only in large nucleated cells but also in platelets, that is, in small anucleate cell fragments. It is suggested that the cells of various types in the course of their attachment to the substratum form pseudopodia and lamellipodia that have a number of common characteristics, including the ability to move the cross-linked surface receptors centripetally.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 115-130 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between the cytoskeleton, stress fiber formation, and cell shape has been difficult to determine in fibroblasts grown in tissue culture. Vagaries in cell shape are complicated, as well, by stochastic cell movements. We dictated the attachment sites and shape of fibroblasts by growing them on square adhesive substrates surrounded by nonadhesive substrates. Cytoskeletal models were made by treating the cells with buffered Triton X-100 and glycerol. The residues were then examined by scanning electron microscopy followed by light microscopy of the same cells. The cytoskeletons of randomly moving cells were examined with whole mount transmission microscopy to confirm images seen with scanning microscopy. The cells thus examined demonstrated definite relationships between ruffling activity and stress fiber terminations, which were limited to the more adhesive, palladium substrate. No stress fibers were seen to end on the lesser adhesive substrate, agarose, and ruffling did not occur across the agarose. Cells too small to fill an entire square tended to extend across one diagonal of the square, and the stress fibers ran parallel to the longest axis of these cells. Larger cells were able to completely fill their squares. The cytoskeletons of these cells were organized in a spatial relation to the square shape of the cells. The cortical meshwork was aligned circularly and diagonally within the cells. Stress fibers appeared to form from the microfilaments of the meshwork and were aligned diagonally across the cells. We conclude that the diagonal arrangement of the stress fibers and cortical meshwork is caused by the same mechanism by which smaller cells spread over the longest axis of a square. Regions of cells where the meshwork was absent or where stress fibers were tightly bundled were occupied by more randomly arranged cytoskeletal components. Regions of tighyly bundled stress fibers did not seem to coincide with regions of cortical meshwork as seen by either whole mount transmission or scanning electron microscopy. Stress fibers were revealed in the light microscope to course beneath more randomly oriented cytoskeletal elements. These “lacework-like” elements were found frequently in square cells. Conspicuous structures in this random lacework were focal points of radially arranged filaments. Our observations suggest a continuity between stress fibers and the cortical microfilaments. The orientation of fibers and filaments was, in turn, dependent on cell shape for organization within the cell.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 173-181 
    ISSN: 0886-1544
    Keywords: cytoplasmic streaming ; motive force ; mitotic cycle ; Physarum polycephalum ; migration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between mitosis and cytoplasmic streaming in the plasmodium of Physarum polycephalum was investigated by simultaneously conducting the following three experiments: (1) identification of the mitotic stages under phase contrast optics, (2) measurement of the rate of oriented migration of the plasmodium on an agar ribbon, and (3) measurement of the motive force of cytoplasmic streaming by the double-chamber method of Kamiya.The migration of the plasmodium almost stopped during synchronous mitosis and the motive force of the flow decreased to 1/4 of the normal level in this period. Gelation of the endoplasm did not occur during the mitotic period, and thus the cessation of the plasmodial migration must have been caused by the diminution of the motive force responsible for cytoplasmic streaming.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 309-315 
    ISSN: 0886-1544
    Keywords: tropomyosin ; avian muscular dystrophy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The isotype pattern of tropomyosin was investigated in normal and dystrophic avian pectroal muscle using two-dimensional gel electrophoresis. Previous reports have shown that adult pectoral muscle of chickens contains only the α-subunit of tropomyosin and a breast-type troponin-T (TN-T), whereas pectoral fetal muscle contains both α- and β-tropomyosin and leg-type TN-T. The change from the fetal to the adult forms begins shortly after hatching. It has been previously reported that avian dystrophic pectoral muscle contains both the leg- and breast-type TN-T; we show that in avian dystrophic muscle there is also persistent expression of the β-subunit of tropomyosin.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 333-341 
    ISSN: 0886-1544
    Keywords: cell motility ; collagen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The motility of an epithelial cell line NBT-II derived from a rat bladder tumor was examined on glass and on collagen. On glass the cells rotate in groups of 2-8 cells. Rotatory migration ceases as cells enter into mitosis; after mitosis, the daughter cells spread out and participate in the rotatory activity of the group. As the number of cells in a group increases the rate of rotatory migration slows, and groups with ten cells or more do not rotate consistently. On collagen NBT-II cells migrate as single cells in a smooth gliding fashion, with the broad lamellipodia as the leading front. After mitosis, the two daughter cells separate at 180° of each other and migrate away independently. Before totally spreading out on the collagen surface, the pair of daughter cells shows a characteristic twist of about 60° from their original position at telophase. The difference in motility of NBT II cells on glass and on collagen is explained in terms of differences in cell-to-cell cohesion and cell-to-substrate adhesion.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 509-523 
    ISSN: 0886-1544
    Keywords: cations ; cilia ; dynein ; ATPase ; microtubule sliding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We recently demonstrated that elevated concentrations (≥ 20 μM) of the dynein substrate MgATP2- inhibit the spontaneous ATP-induced sliding disintegration of isolated, Triton-demembranted Tetrahymena cilia. We have used a turbidimetric assay (ΔA350 nm) and electron microscopy to examine the effect of ATP on sliding disintegration when activated by other divalent cations. Mg2+, Ca2+, and Mn2+ are each capable of activating sliding, but only with Mg2+ and Mn2+ is disintegration inhibited by elevated ATP concentrations (≥ 1 mM). The two major ATPase activities obtained by KCI extraction of Tetrahymena axonemes differ in their cation specificities such that Mg2+ and Ca2+ activate the 21S dynein ATPase with equal efficiency, whereas the 13S axonemal ATPase activity is reduced by ∼ 50% when CaATP2- replaces MgATP2- as substrate. With 1 mM MgATP2- as substrate, 10-7 to 10-2M added CaC12 alleviates the ATP-dependent inhibition of disintegration and likewise represses 13S MgATPase activity. In contrast, free Ca2+ has no effect on either the disintegration response or MgATPase activity. In contrast to Triton-treated cilia, glycerinated cilia, which beat in 1 mM MgATP2-, are inhibited from beating by high CaATP2- concentrations. These substrate specificities suggest that concentration-dependent, substrate inhibition of sliding disintegration may be a manifestation of a physiological mechanism that is mediated by the 13S axonemal ATPase and that may function to modulate sliding during bend formation. However, the effects of added CaCl2 probably do not reflect a physiological mechanism for regulating beat parameters, but rather may result from CaATP2- competing for MgATP2- binding sites on the 13S ATPase, thereby blocking expression of the 13S ATPase.
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    Cell Motility and the Cytoskeleton 2 (1982) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 1-5 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 25-28 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 47-51 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 67-70 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 95-99 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 121-126 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 143-147 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 165-168 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 185-189 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 205-210 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 175-180 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 91-92 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 215-224 
    ISSN: 0886-1544
    Keywords: Mytilus edulis ; 5-hydroxytryptamine ; cilia ; ethanol ; axoneme ; calcium ; filter feeding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The lateral (L) cilia on an isolated filament from the gill of Mytilus edulis remain arrested at the end of their recovery stroke (hands up) when perfused with artificial sea water (ASW). The laterofrontal (LF) cilia continue to be active. The addition of 10% ethanol (ETOH) to the ASW perfusate arrests the LF cilia in a hands-up posture; the L cilia remain undisturbed. By contrast, 10-6 M 5-hydroxytryptamine (5HT) in ASW activates the L cilia and arrests the LF cilia at the end of their effective stroke (hands down). Continued perfusion with 10% ETOH (v/v) in ASW/5HT restores activity to the LF cilia but arrests the L cilia (hands up). These effects are reversible and independent of external Ca2+.Following the detergent extraction of the filament, all gill cilia are inactive. The addition of 0.2 mM ATP in the presence of low Ca2+ (〈 10-7 M) reactivates all model cilia. Under these conditions, 5HT can no longer inhibit the activity of LF cilia and is not required for the activation of the L cilia. This suggests that 5HT acts at a membrane level. An increase in free Ca2+ (〉 10-6 M) arrests the L cilia hands up; the LF cilia remain active. Further Ca2+ increase (〉 10-3 M) induces hands-up arrest of the LF cilia, confirming that the Ca2+ threshold of the two ciliary types is different by several orders of magnitude.The addition of 10% ETOH in low Ca2+ to demembranated reactivated cilia arrests the L cilia hands up while the LF cilia continue to beat. Ten percent ETOH appears to interact with the axoneme, mimicking the effect of high Ca2+ and with the membrane to increase Ca2+ permeability and possibly to inactivate 5HT receptors. These results are discussed in terms of axonemal switching mechanisms and the physiological control of filter feeding in the lamellibranch gill.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 243-255 
    ISSN: 0886-1544
    Keywords: directional macrophage motility ; electric fields ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extracellularly applied electric fields (〈 12 V/cm) strongly influence murine resident peritoneal macrophages (Mø) to undergo directional protrusive pseudopodial activity to wards the positive pole of the electric fields in the absence of exogenously applied chemotactic ligands. Internal and external morphological features were not grossly disrupted by the fields. Directional motility induced by the electric fields was inhibited in the presence of 1.0 mM La3+ or 2.5 mM Mg2+ and 5.0 mM EGTA. Effects of the fields were latent in the inhibited cells and directional motility was expressed after termination of the field and removal of the inhibitors. Receptors for the lectins concanavalin A (Con A) and phytohemagglutinin (PHA-L) were uniformly distributed on the surfaces of Mø with no exposure to electric fields. After exposure to the fields, Con A receptors were preferentially distributed on regions of the Mø surface facing the negative pole and PHA-L receptors were preferentially distributed on those regions facing the positive pole. The possibility that directional Mø motility is regulated by the molecular topography of the cell surface is discussed.
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    Keywords: intermediate filament ; desmosomes ; epidermal keratinocytes ; nuclear envelope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have shown, by indirect immunofluorescence microscopy using an antiserum against the mouse keratin subunit K2 and by electron microscopy, that transformed (PAM) and primary (PME) mouse epidermal cells possess extensive net works of IF bundles. Following trypsinization and replating of PAM cells, IF bundles are seen to move as a continuous net work from a perinuclear zone into the peripheral cytoplasmic regions. In PAM cells lysed in high-ionic-strength solutions containing Triton ×-100 and DNAase-1, IF bundles appear to be closely associated with nuclear envelope remnants and, in some cases, appear to be attached to nuclear pore complexes. PME cells cultivated in low Ca2+-containing medium possess perinuclear birefringent arrays of IF bundles. Within 2 hours of switching the cells to normal Ca2+ levels, the PME IF bundle network moves towards and establishes contact with the cell surface as desmosomes form. Live cells observed by phase contrast and fixed cells observed by immunofluorescence microscopy demonstrate that desmosomes can be distinguished as dark bands separating neighboring cells. There is little difference between the major proteins seen in SDS-polyacrylamide gel profiles of isolated IF bundle net works from PME cells before and after the Ca2+ switch. Therefore, a reorganization of relatively insoluble membrane-associated protein following the Ca2+ switch may be involved in desmosome formation. The isolated IF networks from PAM cells differ in protein composition compared to the PME IF networks. This may be related to the greatly reduced number of desmosomes in PAM cells. The IF bundle system in epidermal cells appears to be involved in shape formation, shape maintenance, the establishment of desmosomes, nuclear centration, and cell-cell contact.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 483-496 
    ISSN: 0886-1544
    Keywords: Cilia ; Ca ; motor control ; ciliates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied quantitative aspects of ciliary motor responses to membrane depolarization in the ciliate Stylonychia using voltage clamp and high-speed cinematograhpy techniques and employing computer-processing methods for evaluation. Depolarizations beyond 4 mV activate the cirri (compound cilia) which are at rest in the absence of a stimulus. The power stroke of activiated cirri is oriented toward the cell anterior. The frequency and duration of beating increase with rising depolarization. With very large positive stimuli (≥ 150 mV) activation of the response is delayed until the end of the voltage step (“off-response”). The peak frequecy is essentially unaltered during sustained depolarization. The frequency drops exponentially following repolarization of the membrane. The time constant of the decay in ciliary activity rises with the amplitude, not with the duration of the depolarization. The ciliary motor response is most adequately represented by the number of evoked ciliary cycles (ciliary work), and appears to be related to the amplitude of the depolarization.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 525-547 
    ISSN: 0886-1544
    Keywords: cilia ; flagella ; ATPases ; dynein ; Chlamydomonas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extraction of isolated, demembranated flagellar axonemes of Chlamydomonas reinhardii with 0.6 M KCl solubilized 77-92% of the total axonemal Mg++ or Ca++-ATPase activity, which sedimented as 18S and 12S peaks in sucrose density gradients. The ATPases of these two peaks were further purified by hydroxyapatite (HAP) column chromatography. The ATPase activity of the 18S peak eluted from the HAP column as a single peak coinciding with the protein peak. The HAP purified 18S ATPase had a specific activity of ∼2.0 ± 0.5 μmoles Pi hydrolyzed min/mg and was associated with four high molecular weight (HMW) polypeptides of ∼ 310,000-340,000 daltons, two intermediate molecular weight (IMW) polypeptides of 78,000 and 69,000 daltons, and eight low molecular weight (LMW) polypeptides of 7,800-19,600 daltons. When the 12S sucrose gradient peak together with a trailing shoulder were chromatographed on HAP, the ATPase activity was eluted in two peaks designated 12S and 10.5S on the basis of the sedimentation properties of their associated polypeptides. The 12S peak contained a single dynein ATPase having a specific activity of ∼ 0.6 ± 0.3 μmoles Pi hydrolyzed min/mg and associated with ∼ 330,000-, 21,700-, and 18, 100-dalton polypeptides. The 10.5S peak contained several high, intermediate, and low molecular weight polypeptides; of these, on HMW polypeptide and one 28,700-dalton polypeptide correlated well with the ATPase activity. The purified ATPases had no polypeptides in common; each therefore represents a discrete dynein. Based on protein recovered in the purified fractions, 18S dynein represents ∼ 9.2% of the total axonemal protein; 12S dynein represents ∼ 4.7% of the axonemal protein.
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    Cell Motility and the Cytoskeleton 2 (1982), S. 405-427 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Calmodulin (CaM) isolated from freshwater mussel gill has been shown to be present in fractions derived solely from epithelial cells of whole gill tissue. This CaM has been used to activate bovine brain phosphodiesterase (PDE) and the dose dependence of trifluoperazine-dihydrochloride (TFP)-mediated inhibition of activation has been investigated. The dose-response curve yields an apparent K1 of 20 μM and suggests that at low concentration (up to 40 μM) TFP inhibits PDE activity in the presence of Ca2+, not by direct action on the enzyme, but by a shunt that negates the effect of mussel gill CaM.To determine whether CaM is physiologically significant for ciliary activity in the mussel gill, the effect of TFP upon the Ca2+-dependent ciliary arrest response of the lateral (L) cells of the gill has been examined. Detergent-treated permeabilized epithelial L cell models are scored for ciliary activity after transfer to reactivation solutions that vary in their free Ca2+ and TFP content. At 10-5 M free Ca2+ (pCa 5), maximum recovery from arrest is observed for TFP concentrations in the range of 25 to 30 μM. TFP-mediated recovery from arrest is never complete, suggesting that in the presence of sufficient Ca2+ the drug irreversibly damages a certain fraction of axonemes. At pCa 7 the cilia reactivate and 25-30.
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    Keywords: flagella ; cilia ; trachea ; microtubules ; crowns ; microtubule assembly ; caps ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distal tips of the central pair and A-microtubules are capped in mammalian and avian tracheal cilia. The capping structures are similar to those found in protozoan cilia and flagella [Dentler, 1981], and consist of a central microtubule cap that links the central microtubules to the membrane or to the ciliary crown and A-microtubule plugs that insert into the lumen of each of the A-microtubule plugs is bound to the central microtubule cap by distal filaments. The ends of the central and outer doublet microtubules are tightly bound to the cap in both intact and in demembranated and reactivated tracheal cilia. Analysis of the displacement of the microtubule tips in cilia fixed at various bend angles revealed that the displacements of A-microtubules are only partially in agreement with those predicted by the sliding filament model [Satir, 1968]. These results are discussed with respect to the regulation of microtubule sliding in capped cilia and the role of the microtubule capping structures in microtubule assembly.
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    Cell Motility and the Cytoskeleton 2 (1982), S. xvii 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 7-12 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 2 (1982), S. 29-34 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 53-57 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 77-81 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 101-106 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 113-119 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 137-141 
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    Cell Motility and the Cytoskeleton 2 (1982), S. 191-194 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
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    Cell Motility and the Cytoskeleton 2 (1982), S. 211-215 
    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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    Cell Motility and the Cytoskeleton 2 (1982), S. 83-86 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 90
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    Cell Motility and the Cytoskeleton 2 (1982), S. 107-112 
    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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  • 91
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    Cell Motility and the Cytoskeleton 2 (1982), S. 127-132 
    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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  • 92
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    Cell Motility and the Cytoskeleton 2 (1982), S. 153-158 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
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  • 93
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2380-2383 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Isomers in the Reaction of Benzofurazan N-Oxides with Phenolate AnionsBenzofurazan 1-oxide 1 reacts with 4-aminophenol in the presence of NaOCH3 to form the isomeric phenazine 5,10-dioxides 3, which are reduced to phenazines 4.
    Additional Material: 1 Tab.
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  • 94
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2409-2422 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mixed Metal Clusters: Metal Exchange via Dinuclear (Cyclopentadienyl)metal CarbonylsIn the tetrahedral cobalt cluster MeCCo3(CO)9 (2a) by means of the dinuclear (cyclopentadienyl)-metal carbonyls [CpM(CO)n+1]2 (1, M = Mo, W, Fe, Ni) one Co(CO)3 unit can be replaced by an isoelectronic unit CpM(CO)n. The best exchange reagent [CpNi(CO)]2 yields the corresponding mixed Co2Ni and Co3Ni clusters, resp. also with other YCCo3(CO)9 clusters (2, Y = Ph, p-Tol, F) and with Co4(CO)12. Thus, by combination of this method with the previously described organometal dimethylarsenide method from YCCo3(CO)9 (2, Y = Me, Ph) the clusters YCCoMoNiCp2(CO)5 (16) with three different metal atoms are obtained. Under modified reaction conditions twofold metal exchange in MeCCo3(CO)9 yields the cluster MeCCoMo2Cp2(CO)7 (15) and in PhCCo2MoCp(CO)8 yields the cluster PhCMoNi2Cp3(CO)2 (17). Of the CoMoNi compound 16a and the MoNi2 compound 17 the molecular structures were determined.
    Notes: In dem tetraedrischen Cobaltcluster MeCCo3(CO)9 (2a) läßt sich mit Hilfe der zweikernigen (Cyclopentadienyl)metallcarbonyle [CpM(CO)n+1]2 (1, M = Mo, W, Fe, Ni) eine Co(CO)3-Einheit durch eine isoelektronische Einheit CpM(CO)n ersetzen. Das beste Austausch-Reagens [CpNiCO]2 liefert auch mit anderen YCCo3(CO)9-Clustern (2, Y = Ph, p-Tol, F) und mit Co4(CO)12 die entsprechenden Co2Ni- bzw. Co3Ni-Heterocluster. Durch Kombination dieser Methode mit der vorstehend beschriebenen Organometall-dimethylarsenid-Methode lassen sich so aus YCCo3(CO)9 (2, Y = Me, Ph) die Cluster YCCoMoNiCp2(CO)5 (16) mit drei verschiedenen Metallatomen gewinnen. Unter veränderten Reaktionsbedingungen ergibt zweifacher Metallaustausch aus MeCCo3(CO)9 den Cluster MeCCoMo2Cp2(CO)7 (15) und aus PhCCo2MoCp(CO)8 den Cluster PhCMoNi2Cp3(CO)2 (17). Von der CoMoNi-Verbindung 16a und der MoNi2-Verbindung 17 wurden die Molekülstrukturen bestimmt.
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  • 95
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2447-2460 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Carbonylation of Zirconocene Hydride ComplexesThe reaction of η2-acylzirconocene complexes 1 with oligomeric zirconocene hydrides (Cp2ZrH2)x (3) or (Cp2ZrClH)x (4) yields binuclear μ-aldehyde-zirconocene hydride complexes 2. The molecular geometry of an example of this type of compound, the μ-acetaldehyde-zirconocene dihydride 2c, in the crystalline state was determined by X-ray analysis. A degenerate „dyotropic“ rearrangement of substrates 2c and e proceeding fast in solution can be detected by dynamic 1H NMR spectroscopy. Reaction of the dinuclear dihydride 2e with carbon monoxide eventually yields the enediolate complex 15-cis. The mechanism of this process of a reductive coupling of two CO molecules by substrate 2e can be traced by several established intermediates. The isolated (η2-formaldehyde)zirconocene complex 11 appears to have a key function in this transformation of carbon monoxide.
    Notes: Die Reaktion der η2-Acylzirconocen-Komplexe 1 mit den oligomeren Zirconocenhydriden (Cp2ZrH2)x (3) oder (Cp2ZrClH)x (4) führt zu zweikernigen μ-Aldehyd-zirconocenhydrid-Komplexen 2. Die molekulare Geometrie eines Beispiels dieser Verbindungsklasse, des μ-Acetaldehydzirconocendihydrids 2c, im Kristall wurde durch eine Röntgen-Strukturanalyse bestimmt. Eine in Lösung rasch verlaufende degenerierte „dyotrope“ Umlagerung der Substrate 2c und e kann durch dynamische 1H-NMR-Spektroskopie erkannt werden. Die Umsetzung des zweikernigen Dihydrids 2e mit Kohlenmonoxid führt schließlich zum Endiolatkomplex 15-cis. Der Mechanismus dieser reduktiven Kupplung zweier CO-Moleküle am Substrat 2e wird durch die nachgewiesenen Zwischenprodukte abgesteckt. Dem isolierten (η2-Formaldehyd)zirconocen-Komplex 11 kommt eine Schlüsselrolle bei dieser Umwandlung des Kohlenmonoxids zu.
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2494-2507 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction Behaviour of Trifluoromethyl Groups Synthesis of 1,3-Azoles from Trifluoromethyl-substituted Hetero-1,3-dienes4,4-Bis(trifluoromethyl)-substituted 1-oxa-3-aza-1,3-butadienes 1, 1-thia-3-aza-1,3-butadienes 2 as well as 1,3-diaza-1,3-butadienes 3 on heating with tin(II) chloride yield 5-fluoro-4-trifluoro-methyl-substituted oxazoles 4, thiazoles 5, and imidazoles 6, respectively. Reaction of the latter with nucleophiles leads to substitution of fluorine bonded to C-5. IR, 1H, 13C, and 19F NMR data of the new compounds are described. A reaction mechanism is proposed.
    Notes: 4,4-Bis(trifluormethyl)-bestückte 1-Oxa-3-aza-1,3-butadiene 1, 1-Thia-3-aza-1,3-butadiene 2 und 1,3-Diaza-1,3-butadiene 3 liefern beim Erhitzen mit wasserfreiem Zinn(II)-chlorid 5-Fluor-4-trifluormethyl-substituierte Oxazole 4, Thiazole 5 bzw. Imidazole 6. Letztere reagieren mit Nucleophilen unter Substitution des an C-5 gebundenen Fluors. Die IR-, 1H-, 13C- und 19F-NMR-Daten der neuen Verbindungen werden beschrieben. Ein Reaktionsmechanismus wird diskutiert.
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2516-2525 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXIV. Selenazole Derivatives from Carbon Diselenide and 3-(Dimethylamino)-2H-azirines3-Selenazolines 5 result from the reaction of carbon diselenide (1) with 2-phenyl-substituted azirines 2a,b via 1,2-cleavage. In the 2,2-dimethylazirine 2c 1 induces 1,3-ring-opening to give the zwitterionic selenazoline 8a which in solution exists exclusively as isoselenocyanate 8B. Reactions of 8 are possible from form A as well as from B. The 2-monosubstituted azirine 2d reacts with 1 to give the 2,2′-biselenazole 23 and the 1-selenomesoxaldiamide 24. The constitution 23 was derived from an X-ray structural analysis.
    Notes: Aus Carbondiselenid (1) und den 2-Phenyl-substituierten Azirinen 2a, b entstehen unter 1,2-Bindungsspaltung die 3-Selenazoline 5. Beim 2,2-Dimethylazirin 2c bewirkt 1 1,3-Ringöffnung zum zwitterionischen Selenazolin 8a, das in Lösung ausschließlich als Isoselenocyanat 8B vorliegt. Reaktionen von 8 sind sowohl aus der Form A wie aus B möglich. Das 2-monosubstituierte Azirin 2d gibt mit 1 das 2.2′-Biselenazol 23 und das 1-Selenomesoxalsäure-diamid 24. Die Konstitution 23 ergibt sich aus einer Röntgenstrukturanalyse.
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2548-2559 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radikalionen, 51. Oxidative Umlagerung von Diphenyldisulfiden in Thianthrenepara-Substituierte Diphenyldisulfide 1-5 mit niedrigen Ionisierungsenergien um 8 eV reagieren mit AlCl3 in CH2Cl2 zu Radikalionen der gleichartig substituierten Thianthrene (Tab. 2, Abb. 2). Beim Aufwärmen der Lösungen beobachtet man ein zweites ESR-Signal, das einem Benzodithiet-Radikalkation (Tab. 2, Abb. 3) zugeordnet wird. Dies ist möglicherweise das reaktive Zwischenprodukt der S8- oder S2Cl2-katalysierten Friedel-Crafts-Chlorierung von Benzol.
    Notes: para-Substituted diphenyl disulfides 1-5 with low gas phase ionization energies of about 8 eV react with AlCl3 in CH2Cl2 to form-radical cations of the corresponding thianthrenes (Table 2, Figure 2). Warming of these solutions produced a second ESR signal which is attributed to a benzodithiete radical cation (Table 2, Figure 3). This is possibly the reactive intermediate in the S8 or S2Cl2 catalyzed Friedel-Crafts chlorination of benzene.
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2592-2605 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Synthese von Spiro[adamantan-[1,2]dioxetanen]Die Spiroadamantangruppe stabilisiert thermisch unbeständige 1,2-Dioxetane ausreichend und ermöglicht dadurch deren Isolierung. Diese stabilisierende Gruppe erlaubt erstmals, schwefel-substituierte Dioxetane 9k und 1 herzustellen und mittels 13C- und 1H-NMR-Spektroskopie nachzuweisen. Tetraphenylporphyrin-photosensibilisierte Singulett-Sauerstoff-Cycloaddition an 2-Methylenadamantane 8 ist die Methode der Wahl zur Erzeugung der Spiro[adamantan-[1,2]-dioxetane] 9, vorausgesetzt, der Methylenkohlenstoff trägt keine Alkyl- oder Arylreste. Die Kopecky-Methode, d.h. Hydroperoxybromierung der 2-Methylenadamantane 8 und anschließende Dehydrobromierung, führt nicht zur Bildung der Dioxetane 9.
    Notes: It is shown that the spiroadamantane group stabilizes thermally labile 1,2-dioxetanes sufficiently to permit isolation. With the help of this stabilizing group it was possible to prepare the first sulfur substituted dioxetanes 9k and 1 and characterize them by low temperature 13C and 1 NMR spectra. Photosensitized singlet oxygenation at low temperature, using either polymer-bound Rose Bengal or tetraphenylporphyrin as sensitizer in methylene chloride, of the corresponding 2-methyleneadamantanes 8 was the method of choice for the preparation of the spiro[adamantane-[1,2]dioxetanes] 9, provided that the methylene carbon bears no alkyl or phenyl substituents. The Kopecky method, i.e. hydroperoxybromination of the 2-methyleneadamantanes 8 and subsequent dehydrobromination, proved unsuccessful to prepare the dioxetanes 9.
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    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2635-2642 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Method for the Synthesis of 2,4-Disubstituted Morpholinesω-Acetoxyacetophenones (acyloin esters) 1 react with secondary aminoethanols 3 and formic acid according to Leuckart-Wallach's reaction to form 2-(aryl),4-disubstituted morpholines 5. Intermediates of the reaction are discussed. The ω-halogenacetophenones react analogically.
    Notes: Bei der reduktiven Aminierung von ω-Acetoxyacetophenonen (Acyloinestern) 1 mit sekundären Aminoethanolen 3 und Ameisensäure nach der Leuckart-Wallach-Reaktion werden 2-(Aryl),4-disubstituierte Morpholine 5 gewonnen. Die Zwischenstufen der Reaktion werden diskutiert. Die ω-Halogenacetophenone reagieren analog.
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