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  • Life and Medical Sciences  (697)
  • Organic Chemistry  (682)
  • AERODYNAMICS  (479)
  • 1980-1984  (1,858)
  • 1983  (1,858)
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  • 1980-1984  (1,858)
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 131-150 
    ISSN: 0886-1544
    Keywords: flagella ; Chlamydomonas ; motility ; flagellar reversal ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using a uniflagellate mutant of Chlamydomonas and flash photomicrography at 300 Hz, we have obtained detailed information on the forward and reverse beating modes of Chlamydomonas flagella and on the relationship between rotation of the uniflagellate cell and the bending cycle of the forward mode. Flagella ranging in length from 5 to 15.5 μm were photographed. There is a decrease in wavelength and an increase in curvature in the principal bends when the length of the flagellum is less than the normal length of 12-13 μm, but these changes are not sufficient to maintain similarity of the bending pattern. In the reverse mode, the flagellum propagates symmetrical, planar, undulatory waves with a shear amplitude which is the same as in the forward mode: there is a 19% increase in beat frequency and a similar decrease in wave length. The reorientation of the flagellar beat direction towards the axis of the cell in the reverse mode is caused both by the decrease in asymmetry of beat and by activation of sliding in the principal bends at an earlier time in the beat cycle, relative to the time of activation of sliding in reverse bends. There are additional rare modes of beating which may be related to intermediate stages in the transition between forward and reverse beating modes.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 123-130 
    ISSN: 0886-1544
    Keywords: taxol ; microtubules ; flagellar outer doublets ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Taxol induces the in vitro assembly of calcium stable microtubules from flagellar tubulin solubilized from sea urchin (Strongylocentrotus purpuratus) sperm tail outer doublets by sonication. Assembly occurs in the presence or absence of exogenous GTP. The drug (10 μM) reduces the critical concentration of protein required for assembly to ≤0.04 mg/ml. 3H-Taxol binds specifically to both isolated flagellar outer doublets and to reassembled microtubules with calculated maximal binding ratios of 0.25 and 1.32 moles taxol/mole polymerized flagellar tubulin dimer, respectively. We suggest that the discrepancy in maximal binding ratios may result from the presence of an endogenous molecule(s) along the surface of outer doublet microtubules that restricts taxol binding to that structure.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 185-197 
    ISSN: 0886-1544
    Keywords: dynein ; microtubules ; cell motility ; fibroblasts ; in vitro ; phagokinetic tracks ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Patients with Kartagener syndrome (KS) show defects in ciliary and flagellar movement that are usually associated with the partial or total absence of dynein side arms from axonemal microtubules. Dynein is essential for such movements, but its involvement in other cellular (particularly microtubule-related) processes is unknown. It has recently been reported that neutrophils from KS patients show impaired motility including responses to chemotactic stimuli, suggesting that dynein-like proteins may be generally involved in motile processes. In support of this, we have now found that spontaneous motility of cultured skin fibroblasts from KS patients is also markedly impaired. Three cell lines derived from skin explants of KS patients with deficient dynein side arms in nasal cilia and eight cell lines derived from normal volunteers were studied. Fibroblasts were seeded into dishes containing colloidal gold-coated cover glasses [Albrecht-Buehler, 1977], incubated for 24 h at 37°C, and the area of cell “phagokinetic” tracks determined.Each cell line studied in this manner reproducibly displayed an amount of spontaneous motility characteristic for that cell line. The mean track area (± SE) for all control cells studied was 14.6 ± 0.5 × 103μm2 whereas for KS fibroblasts was 8.7 ± 0.4 × 103μm2 (P 〈 0.001). Immunofluorescence microscopy using antitubulin and antihuman 210 K MAP antibodies revealed no differences in the staining patterns between control and KS fibroblasts. Pinocytic rates were identical, and the complement of tubulin and major microtubule associated proteins as seen on one-dimensional SDS polyacrylamide gel autoradio-graphs appeared similar for control and KS cells. Thus, the observed motility defect is probably not the result of alterations in the occurrence or distribution of microtubules or in the occurrence or binding of the major microtubule-associated proteins. This defect in cellular motility may be related to the absence of dynein or may reflect another independent cellular defect.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 321-332 
    ISSN: 0886-1544
    Keywords: microtubule sliding ; interdoublet links ; radial spokes ; bend formation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ciliary axonemes from Tetrahymena extracted by KCl to remove the dynein arms reveal an orderly array of interdoublet links connecting adjacent A-B or A-A subfibers. The links repeat every 96 nm at a stable site on the A subfiber positioned near the bases of radial spokes 2 and 3. Both links and radial spokes are in lateral register across the nine successive doublets of unbent axonemes. In contrast, bent axonemes or those reactivated by ATP to undergo partial sliding disintegration exhibit systematic displacement of the interdoublet links. The links show no evidence of having elastic or other extendable properties and, therefore, must have undergone intermittent attachment with nonstructural binding sites on the adjacent subfiber. These observations suggest a more dynamic role for the interdoublet links in ciliary motion than previously has been envisioned.
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  • 5
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 213-226 
    ISSN: 0886-1544
    Keywords: microtubules ; fertilization ; cell division ; sea urchin ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The microtubule-containing structures that appear in eggs during fertilization and cell division in the sea urchins Lytechinus variegatus and Arbacia punctulata were detected by antitubulin immunofluorescence microscopy of detergent extracted cytoskeletal preparations. The extraction buffer, which is composed of 0.55 mM MgCl2, 10 mM EGTA, 25 mM MES, 25% glycerol, 1% Nonidet P-40, and 25 μM PMSF, pH 6.7, allows for dramatically improved fluorescent images compared to those obtained using conventional staining procedures, with residual background staining being reduced to near zero.The immunofluorescent images obtained using this technique provide information on several motile events that occur during the first cell cycle. This technique demonstrates that all of the cytoplasmic microtubules are associated with the incorporated sperm's centrioles during female pronuclear migration. This changes during the centration of the male and female pronuclei at which time a monastral array of microtubules forms in the egg's cytoplasm. A large proportion of the monastral microtubules do not appear to be associated with the centrioles. At prophase and early metaphase, the centrioles are the dominant microtubule organizing centers (MTOCs) consistent with mitotic theories that the kinetochore catches, but does not initiate, microtubules. Observations of intercentriolar distances show that there are three stages of pole separation during the first cell cycle. The initial separation occurs during pronuclear centration, the second during the streak stage, and the final one during the late stages of mitosis. At telophase, polar microtubules appear to extend into the cortex supporting the cell surface at all regions except the presumptive cleavage site.
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  • 6
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 281-282 
    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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  • 7
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 307-320 
    ISSN: 0886-1544
    Keywords: contact inhibition ; contact guidance ; growth cones ; cell-cell interactions ; neuronal contact behavior ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The outcome of contact interactions involving neurons and nonneurons varies depending on the cell types involved. When neuronal growth cones from either ciliary (motor) or dorsal root (sensory) ganglia directly contact the lamellipodium of an embryonic heart fibroblast, both neurite elongation and fibroblast locomotion are inhibited. This occurs in spite of the fact that cell-surface activity in both cells continues unabated. Such contact inhibition is not observed when homologous ganglionic nonneurons are involved in the interaction. In fact, these cells become intimately associated with growth cones and/or neuritic shafts as a result of the contact. The detailed nature of the respose to contact exhibited by nerves and nonnerves varies not only with cell type but also with the portion of the cell involved in the contact. Growth cone filopodia tend to actively palpate the fibroblast surface, whereas spread regions, termed “veils,” form areas of apposition with fibroblast lamellipodia. This latter situation resembles the “typical” contact inhibition of locomotion that occurs following embryonic heart fibroblast-fibroblast interactions. Growth cones also frequently exhibit contact guidance when interacting with nonruffling lateral surfaces of heart fibroblasts.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. ix 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 9
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 699-719 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 10
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983) 
    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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  • 11
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 431-438 
    ISSN: 0886-1544
    Keywords: myotendinous junction ; laminin ; type IV collagen ; heparan sulfate proteoglycan ; alpha actinin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The muscle-tendon junction of murine skeletal muscles has been analyzed by a variety of extraction techniques, by myosin subfragment-1 binding experiments, and by ultrastructural immunocytochemistry. The results indicate that the muscle-tendon junction is composed of four distinct domains: an intracellular domain, the internal lamina; a domain connecting the internal lamina with the lamina densa of the external lamina, the connecting domain; the lamina densa; and a domain which attaches the lamina densa to the collagen fibers, the matrix. Each of these domains is distinct with respect to position, three-dimensional organization, and molecular composition, and is therefore considered to have a unique role in the transmission of contractile force.
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  • 12
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 579-588 
    ISSN: 0886-1544
    Keywords: calcium-dependent protease ; contractile proteins ; platelets ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 13
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 609-622 
    ISSN: 0886-1544
    Keywords: erythrocyte membrane ; surface elastic shear modulus ; membrane viscosity ; hereditary disorders of blood ; membrane yield ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Measurements of the mechanical properties of the erythrocyte membrane provide a direct assessment of the proper function of its structural components. To assess the effects of alterations in molecular structure on membrane mechanical properties, measurements have been performed on cells from six individuals whose membranes contain inherited, biochemically characterized structural defects. Because the contribution of the memmbrane skeleton to the mechanical behavior of the membrane is most evident in shear deformation, mechanical experiments were performed to measure the material constants which characterize the response of the membrane to shear force resultants. The surface elastic shear modulus characterizes the elastic response of the membrane; the yield shear resultant is the maximum shear force resultant which the membrane can support elastically; and the plastic viscosity coefficient characterizes the rate of membrane deformation when the elastic limit has been exceeded.Generally, it was found that when the molecular defect is found to occur in a region of the skeleton which is stress-supporting, the maximum elastic strength of the membrane is reduced. However, the magnitude of the reduction can be quite different for membranes having similar or even identical defects. In some cases the differences can be attributed to the removal of the most fragile cells of the population by the spleen, but other results indicate that the biochemical description of the defects may be incomplete. These results emphasize the need for further refinements both in the biochemical characterization of membrane skeleton structure and in the description and measurement of membrane mechanical properties.
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  • 14
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 671-682 
    ISSN: 0886-1544
    Keywords: actin ; cytoskeleton ; membrane connections ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Recently, molecules highly related to erythrocyte spectrin have been identified in nonerythroid cells. Here we summarize our current understanding of these molecules and suggest a model for their organization. Significant differences exist between this family of proteins isolated from mammalian cells and avian cells, and this may explain the variability in antibody preparations as well as differences in peptide maps of these subunits which have been reported. We have prepared antibodies specific for the variant subunits of the spectrinlike proteins fodrin, spectrin, and TW260/240 and analyzed the distribution of these variant subunits in different chicken cell types as well as their developmental distribution in the intestine. The results suggest that fodrin is the general member of this family of proteins and can even coexist with other spectrinlike proteins in the same cells.
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  • 15
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 31-46 
    ISSN: 0886-1544
    Keywords: polymorphonuclear neutrophils ; motility ; F-actin distribution ; adhesion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Directed movement of polymorphonuclear neutrophils (PMN) requires cell polarization and the orderly making and breaking of cell-substrate contacts. We compared the movement of human PMN suspended from the underside of glass coverslips to that of PMN seen in “profile” on fibers, using brightfield, differential interference contrast and reflection interference microscopy. Images were recorded on film and videotape and analyzed in real time and time lapse. The distribution of F-actin was observed with image-enhanced fluorescence microscopy after staining with NBD-phallacidin.PMN exhibited two patterns of motility. Fifteen to twenty-five percent of cells moved in a low profile gliding pattern and exhibited cauded displacement of dorsal surface folds. Most PMN made progress by cycles of partial release of the lamellipodium from the substrate and anterior advance followed by arching or rolling and lamellipodial reassociation with the substrate. Cells stimulated with bacteria, casein, or chemotactic formyl peptide rarely spread on the coverglass but waved into the medium attached only by the uropod. Eventually, many detached completely from the substrate. Cells confined to the substrate surface with overlying agarose were able to locomote when confronted with these substances.F-actin was irregularly distributed in nonpolarized suspended cells but concentrated in the lamellipodium in polarized cells. As cells arched along a substrate, F-actin accumulated in foci corresponding to the substrate-PMN interface, particularly at the uropod and retraction fibrils. Conversely, cells that were physically restricted to movement in the plane of the substrate surface by overlying agarose exhibited diffuse F-actin along the entire cell. Suspended PMN polarized with formyl peptide and incubated with Con A accumulated F-actin at the uropod. These observations suggest that both PMN locomotion and the movement of Con A binding sites involve the caudad redistribution of F-actin.
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  • 16
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 79-91 
    ISSN: 0886-1544
    Keywords: mitosis ; anaphase ; microtubules ; nocodazole ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During early anaphase PtK1 cells were briefly treated with the rapidly reversible microtubule (MT) poison nocodazole. This treatment abruptly stopped chromosome motion and effected a large decrease in spindle birefringence. On removal of the drug, chromosome to pole motion (anaphase A) returned, though at a lesser rate but not extent than untreated cells. In most cases elongation of the pole-pole distance (anaphase B) also occured, at both a rate and to an extent less than in untreated cells. During the recovery period following drug arrest spindle birefringence did not return to pretreatment levels. Electron microscopic analysis of nocodazole arrested, or arrested and released, cells revealed extensive disassembly of the nonkinetochore class of MTs (nkMTs), particularly evident in the astral region. Microtubules seen in the interzone region were largely fragments of midbody precursors. Kinetochore MTs (kMTs) appeared to be unaffected by the brief drug treatment chosen for these experiments. Analysis of MT profiles seen in transverse sections of the interzone region indicated in treated and released cells approximately 60% fewer MTs. This may suggest that chromosome motion during anaphase is not dependent on interactions between kMTs and nkMTs and separation of the spindle poles can occur in the presence of disrupted interzonal MTs.
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  • 17
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 113-121 
    ISSN: 0886-1544
    Keywords: coelomocytes ; filopodia ; whole cell translocation ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have utilized a video-enhanced contrast system coupled to a DIC-equipped microscope to examine the motility of both whole coelomocytes and individual filopodia. When the cells are left in diluted coelomic fluid, they exhibit a fibroblast-like mode of translocation across the substrate. These cells extend lamellipodia at their advancing margin and develop retraction fibers at the trailing edge. Filopodia are actively extended from the lamellipodia of the advancing margin. Cells that are washed free of the coelomic fluid and placed in an isotonic buffer lose their ability to translocate. Filopodia on these stationary cells are seen to undergo a series of waving and bending motions. These motions are rapid and result in a filopodium folding back upon itself only to reextend later. Both forms of motility are discussed in light of the existing structural and biochemical knowledge of this and other cell types.
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  • 18
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 167-184 
    ISSN: 0886-1544
    Keywords: saltatory organelle movements ; ciliary movement ; dynein ; vanadate ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To test the idea that saltatory organelle movements of nonmuscle cells might be driven by microtubule-dynein interactions, we microinjected vanadate into several different types of cultured cell. Solutions of sodium metavanadate made up in a simple buffered salt solution were pressure microinjected into fully spread cells in an open-topped culture chamber placed on the stage of an inverted microscope. The cells were observed by oil-immersion phase-contrast optics and results were recorded on movie film. Vanadate, at 10-5-10-2 M, microinjected into cultured chick embryo fibroblasts, failed to inhibit organelle movements. To test the effectiveness of vanadate's inhibitory action under living cell conditions, ciliated epithelial cells were micro-injected. In these cells even the smallest microinjection of 5 × 10-5 M vanadate caused an immediate cessation of ciliary beating. Moreover, in cells that were well spread it was found that whereas vanadate, at 5 × 10-5 × 10-3M, inhibited ciliary motion, it failed to inhibit organelle saltations in the same cell. To determine whether vanadate would inhibit a living actin-myosin system, myocardial cells were also microinjected. Following microinjection of 5 × 10-5 and 5 × 10-4M vanadate a temporary tonic contraction (which also occurred following microinjection of buffer alone) was followed by regular beating. Taken together these results demonstrate that in living cell systems microtubule-dynein interactions are as sensitive to vanadate inhibition as they are in demembranated model systems, and that a working actin-myosin system in a living muscle cell does not share this great sensitivity. In light of the pronounced differential inhibitory effects of vanadate on the movements of cilia and organelles, our results suggest that saltatory organelle movements in chick embryo fibroblasts and rabbit oviduct epithelial cells are unlikely to be brought about by microtubule-dynein interactions.
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  • 19
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983) 
    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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  • 20
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 399-403 
    ISSN: 0886-1544
    Keywords: focal contacts ; cytoskeleton ; microinjection ; mobility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dynamic state of cytoskeletal protiens actin and vinculin was studied in living cells using microinjection of fluorescently-labeled proteins combined with fluorescence photobleaching recovery (FPR). It is shown that both proteins maintain a dynamic equilibrium between their diffusible pools in the cytoplasms and their “organized” cytoskeletal fraction. These interrelationships could be simulated in model systems consisting of isolated substrate attached membranes. It was demonstrated that fluorophore bound vinculin was incorporated into the exposed focal contacts and that this binding was largely actin independent. These results are in line with the hypothesis that local contacts induce binding of vinculin to the endofacial surface of the membranes and that this region serves as a nucleation center for the assembly of actin bundles.
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  • 21
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    Cell Motility and the Cytoskeleton 3 (1983), S. 391-397 
    ISSN: 0886-1544
    Keywords: focal contacts ; microfilaments ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of structural elements in the organization and maintenance of focal contacts was studied by microinjecting into tissue culture cells specific probes which interfere with filamentous actin or with vinculin: actin interaction. Injection of actin capping proteins from Physarum and brain resulted in breakdown of microfilament bundles starting at their distal ends and in loss of focal contacts. This process was fully reversible. Injection of a high affinity antibody against chicken gizzard vinculin led to partial breakdown of microfilament bundles concomitant with disruption of focal contacts with vinculin remaining at the plasma membrane. This process was irreversible.
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  • 22
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    Cell Motility and the Cytoskeleton 3 (1983), S. 405-417 
    ISSN: 0886-1544
    Keywords: vinculin ; focal contacts ; microfilaments ; transformation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Talin is a recently identified cytoskeletal protein with a polypeptide molecular weight of 215,000 daltons. In cultured fibroblasts talin has been localized by immunofluorescence in adhesion plaques (focal contacts), in the ruffling membranes and leading lamellae of the cell periphery, and in fibrillar patterns that align with microfilament bundles and/or with cell surface fibronectin. These cellular locations suggest that the protein could function either in the attachment of microfilaments to the plasma membane or in the organization of microfilaments close to membrane attachment sites. Cell transformation by viruses such as Rous sarcoma virus disrupts the normal organization of talin, and in most transformed cells talin appears distributed diffusely through the cytoplasm. In a few cells talin is detected in doughnut-shaped aggregates, as a ring surrounding a central core of actin. The significance of these structures is uncertain, but in some cells the individual structures will condense to form much larger aggregates with a striking appearance when viewed by immunofluoresence microscopy.
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  • 23
    ISSN: 0886-1544
    Keywords: chondrocytes ; matrix vesicle formation ; actin ; tubulin ; myosin ; vinculin ; alkaline phosphatase ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Matrix vesicles, extracellular microstructures known to eb involved in endochondral calcification, are rich in alkaline phosphatase and have been shown to contain actin. The mechanism of matrix vesicle formation in chondrocytes in not well understood. Chondrocytes from the epiphyseal growth plate, when grown in primary culture, elaborate alkaline phosphatase-rich vesciles. We examined the distribution of the cytoskeletal proteins actin, myosin, tubulin, and vinculin at various time-points during culture using indirect immunofluorescent labeling. Concomitantly, the production of alkaline phosphatase-containing matrix vesicles was also followed. Cell morphology changed noticeably at two distinct stages during the 22-day culture period: Immediately after release from the growth plate the cells were founded, but after 4 days of cultre they began to spread out and acquire irregular shapes with distinct filopodia. By 13 datsm as tge cekks attaubed confluency, they reacquired a rounded, polygonal appearance. At all time-point, tubulin was seen as a dense network of microtubules radiating from the perinuclear region throughout the cytoplasm toward the cell periphery. Initially actin was seen in filamentous from, but displayed a punctate distribution focused at contact points during the cell-spreading stage of culture. After confluency, actin was concentrated at cell-cell junctions. Initially, vinculin was diffusely distributed, but became focused in multiple adhesion plaques and at the termini of filpodia during the cell-spreading stage of culture. Following confluency vinculin became concentrated at cell-cell junctions. Myosin was observed at all time-points in small, intensely localized focal points in the cytoplasmic region of the cells and was consistently absent from the nuclear and peripheral regions. The amount of myosin in the cells increased steadily with time in culture. Elaboration of alkaline phosphatase-rich vesicles, which corresponded closely with the rounded morphology of early and late stages of culture, may be correlated with contact inhibition.
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  • 24
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    Cell Motility and the Cytoskeleton 3 (1983), S. 525-534 
    ISSN: 0886-1544
    Keywords: actin ; actin-membrane interactions ; coelomocytes ; calmodulin ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Coelomocytes from several echinoderm species undergo an actin-mediated cytoskeletal transformation once subjected to hypotonic shock. In this study, coelomocytes from the sea urchins Lytechinus variegatus and Arbacia punctulata were induced to “transform” by treatment with 〉 5 μM of the calcium ionophore A23187 in the presence of external Ca++. The dependence of ionophore transformation on external Ca++ and the lack of chlorotetracycline staining indicates that these cells rely on external Ca++ sources. NBD-phallacidin (7-Nitrobenz-2-oxa-1,3-diazole-phallacidin) staining of lysolecithin permeabilized cells and wholemount transmission electron microscopy (TEM) show that similar reorganizations of the actin cytoskeleton take place during hypotonic shock and ionophore transformation, although actin filament bundling is less apparent in A23187-treated cells. As has been shown with hypotonic shock transformation, the ionophore elicited shape change is inhibited by anticalmodulin drugs. Greater than 10 μM concentrations of W 13 inhibit filopod formation, while this drug's less active structural analogue, W 12, exhibits no effects. W 13 also appears to disrupt actin filament-membrane associations in the cells. Fluorescent localization of calmodulin using a photooxidized derivative of trifluoperazine indicates a general cytoplasmic distribution with some concentration in filopod core bundles. Coelomocyte transformation may be an example of a cellular shape change regulated by Ca++ through the action of calmodulin modulation of actin-membrane interactions.
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  • 25
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    Cell Motility and the Cytoskeleton 3 (1983), S. 553-565 
    ISSN: 0886-1544
    Keywords: microfilaments ; cytoskeleton ; simian virus 40 ; cell adhesion ; cell surface ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to assess the role of cytoskeletal structure in modulating cell surface topography during cell transformation, cytoskeletal organization of 3T3 mouse cells transformed with a tsA mutant of simian virus 40 (SV40) was studied in detail by correlative light and electron microscopy. Detergent-extracted, criticalpoint dried whole cells observed in the electron microscope were seen to contain well-organized microfilament bundles (stress fibers) traversing the longitudinal axis of cells grown at the restrictive temperature (39°C). When grown at the permissive temperature (32°C), cells prepared in this manner were not observed to contain such structures. However, when semithin sections (0.5 μm) were viewed by transmission electron microscopy at 120 kV, short microfilament bundles were seen in 32°C-grown cells. There was an alteration in the morphology of these structures at sites of attachment to the substratum (focal contacts), and they were shorter in length than microfilament bundles of 39°C-grown cells. A difference was also observed between the two phenotypes in the layer of microfilaments associated with the dorsal cell surface. Since it is this layer that directly determines cell surface architecture, it is proposed that changes in microfilament bundle-generated surface tension are responsible for alterations of this layer, leading to an altered cell surface morphology. Tension may be modified by disturbances in focal contacts (or adjacent regions) or altered actin-associated protein(s).
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  • 26
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    Cell Motility and the Cytoskeleton 3 (1983), S. 567-577 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; murine leukemia viruses ; formaldehyde fixation ; membrane permeability ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mouse fibroblasts chronically infected with Moloney murine leukemia virus (MuLV) were fixed using variable amounts of formaldehyde, then examined by indirect immunofluorescence light microscopy. Several antisera were employed to detect both external and internal antigens associated with the cells, eg, MuLV gp70, tubulin, vimentin, and actin. Our results indicate that the cell membranes could be partially permeabilized to IgG molecules directed against the three cytoskeletal antigens only after 3.7%, but not 1%, formaldehyde treatment. Complete permeabilization was achieved by subsequent acetone treatment of cells after 3.7% formaldehyde fixation. In such cells, normal-appearing cytoskeletal networks of microtubules and intermediate filaments were observed. Stress fibers were also seen; however, they appeared less numerous and thinner than those of uninfected mouse fibroblasts. Further, a significant amounts of F-actin fluorescence was localized in granules in the cytoplasm of infected cells. Similar observations were made using JLS-V9 mouse cells chronically infected with 334C virus, another MuLV. These results taken together suggest that subtle differences exist in the organization of actin within MuLV-infected and uninfected mouse fibroblasts.
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  • 27
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    Cell Motility and the Cytoskeleton 3 (1983), S. 693-697 
    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 3 (1983), S. 657-669 
    ISSN: 0886-1544
    Keywords: Hela spectrin ; membrane ; cytoskeleton ; filamin ; actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: From 30-40 g of Hela-S3 cells grown in suspension, 0.25-0.50 mg of spectrin has been purified by conventional biochemical procedures starting from a low ionic strength extraction at alkaline pH of crude Hela membranes. Hela spectrin consists in its native form of a tetramer α2β2 of two high molecular weight polypeptides (240,000 and 230,000 daltons). Three different populations of Hela membranes depleted of both spectrin and actin have been prepared on discontinuous sucrose gradients. Surprisingly, spectrin will reassociate with only the heavier membrane fraction. This reassociation is specific for Hela spectrin, since three other purified Hela proteins as well as human erythrocyte spectrin do not reassociate under the same conditions. This binding is not due to the presence of traces of actin still present in the membrane fraction since two Hela actin-binding proteins (filamin I and II) do not show any significant binding to this fraction. The nature of the membrane-binding site for Hela spectrin is discussed.
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  • 29
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    Cell Motility and the Cytoskeleton 3 (1983), S. 683-691 
    ISSN: 0886-1544
    Keywords: α-spectrin ; coelomocytes ; filopodia ; actin/membrane interactions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the presence and localization of an α-spectrinlike protein and its potential role in the morphological transformation of sea urchin coelomocytes. In immunofluorescence images there is a diffuse fluorescence throughout the petaloid cytoplasm, indicating a random distribution of the spectrinlike protein prior to the transformation. As these cells form filopodia, there is a coincident appearance of a spectrinlike protein, as seen in fluorescent images, at the site of filopodial initiation. As the filopodia continue to form and lengthen, the spectrin localization parallels their development. There is a single polypeptide observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels of whole coelomocyte lysates that cross-reacts with the anti-α-spectrin immunogen and comigrates with it at 240 kilodaltons.
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  • 30
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    Cell Motility and the Cytoskeleton 3 (1983) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 31
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    Cell Motility and the Cytoskeleton 3 (1983), S. 47-60 
    ISSN: 0886-1544
    Keywords: neutrophil granulocytes ; motility ; locomotion ; cell-shape ; cell-substratum adhesion ; f-Met-Leu-Phe ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Activation of the motile apparatus by chemokinetic factors cannot be reliably assessed in cells that are attached to a solid substratum because motility can be totally abolished by excessive adhesion. It is however, necesary to quantify the activation of the motile apparatus in order to analyze and understand chemokinetic responses.It was the purpose of the present work to establish morphological criteria that can be used to quantify motility in nonadherent (floating) neutrophils and to predict the locomotor response under conditions of limited adhesion. The proportion of neutrophils performing crawling-like movements (polarized cells) in suspension correlates very closely with stimulated locomotion at low to optimal concentration of f-Met-Leu-Phe, ie, under conditions of limited adhesion. Reduced locomotion at supraoptimal concentrations of f-Met-Leu-Phe has also morphological correlates. The major feature is the decrease in the proportion of neutrophils performing crawling-like movements and the corresponding appearance of cells that are motile but not polarized in suspension and that do not locomote on the substratum. Concentration-dependent changes in neutrophil length and in the proportion of polarized neutrophils with and without tail were also observed. The locomotor potential of neutrophils under conditions of limited contact with the substratum can be predicted on the basis of their motile behavior, in particular the proportion of cells showing crawling-like movements, in suspension. In combination with measurements of adhesion the procedure should permit a more complete analysis of the regulation of chemokinetic responses.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 111-111 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 33
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    Cell Motility and the Cytoskeleton 3 (1983), S. 1-19 
    ISSN: 0886-1544
    Keywords: cytoplasmic transport ; Saltation ; microtubules ; keratocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We report the first direct demonstration that the cytoplasmic transport of organelles and vesicles (collectively called particles) takes place along microtubules. Living keratocytes from the corneal stroma of the frog, Rana pipiens, were observed with Allen video-enhanced constrast, differential interference constrast (AVEC-DIC) microscopy [Allen et al, 1981]. In sufficiently thin regions of these cells a network of linear elements was visible. When particles were observed in motion, they always moved along these linear elements. The linear elements remained intact and in focus on the microscope when lysed in a cell lysis solution that stabilized microtubules. Preparations were then fixed in formaldehyde, washed with phosphate-buffered saline (PBS), incubated with rabbit antitubulin, washed with PBS, stained with rhodamine-conjugated goat antirabbit, and washed with PBS. The extracted cells continued to remain in place and in focus on the microscope throughout these procedures. The same cells were then observed using epifluorescence optics and a silicon-intensified target (SIT) video camera. A network of fluorescent linear elements was seen to correspond in number, form, and position to the linear elements seen in the live AVEC-DIC image. Taken together, the AVEC-DIC and fluorescence microscopy observations prove that the linear elements along which particles move are microtubules (MTLEs). The observed particle speeds, pause times, and distances moved varied widely, even for the same particle on the same microtubule. Particles were also observed to switch from one microtubule to another as they were transported. The polarity of the microtubules did not seem to affect the particle direction, since particles were observed to move in both directions on the same MTLE. When not in motion these particles behaved as if anchored to the microtubules since they showed negligible Brownian motion. Finally, it was observed that an elongate particle could move onto two intersecting linear elements such that it was deformed into an inverted “Y” shape. This indicates that there may be more than a single site of attachment between the force generator and the particle.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 61-77 
    ISSN: 0886-1544
    Keywords: non-actin filaments (NAF) ; flagellar rootlets ; pusule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flagellar rootlets play an important role in “primitive motile systems.” They are made of filaments able to contract by twisting and Ca+2 binding. The pusules of Dinoflagellates appear to be under the control of large bundles of 2.4 nm nonactin filaments that correspond to the striated rootlets of their two flagella.
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  • 35
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    Cell Motility and the Cytoskeleton 3 (1983), S. 199-210 
    ISSN: 0886-1544
    Keywords: sperm ; flagellum ; motility ; cAMP ; freeze-thawing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Demembranated and membrane disrupted bull sperm models exhibit an increase in motility when exposed to cAMP. Tritium-labeled cAMP was used to locate the initial site of action of cAMP in the modeled sperm preparations. cAMP did not bind selectively to the modeled cells, and the presence or absence of plasma membrane fragments on the models did not significantly alter this result. When suspension medium taken from modeled sperm preparations was subjected to gel filtration on Sephadex G25-150 columns, cAMP bound to a high molecular weight component that eluted with the void volume. The responsible binding factor is a soluble component that is released when the plasma membranes of the sperm are disrupted during the modeling procedure. To test the importance of the cAMP binding factor, modeled sperm were centrifuged, the super-natant solution was decanted, and the cells were resuspended in fresh medium. After this treat-ment the cells could be restored to motility with Mg-ATP but no longer exhibited a response to cAMP. Furthermore, addition of cAMP binding factor isolated by gel filtration partially restored the response of these sperm to cAMP. Investigation of the properties of the cAMP-binding factor have confirmed that it is specific for cAMP, with a much lower affinity for AMP and cGMP. In the pre-sence of a large excess of unlabeled cAMP the labeled complex has a half-life of approximately 1 hour. Our results indicate that the action of cAMP on the motility of modeled sperm is mediated by its attachment to a high molecular weight, soluble component of the cell cytoplasm.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 211-212 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 3 (1983), S. i 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 38
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    Cell Motility and the Cytoskeleton 3 (1983), S. 439-447 
    ISSN: 0886-1544
    Keywords: actin filament ; adhesion ; muscle ; tendon ; biomechanics ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Juctions between skeletal muscle cells and tendon collagen fibers transmit forces generated by muscle cells to the skeletal system. Since force trajectories across adhesive joints partly determine the stresses at the joint (eg, shear or tensile), the geometry of actin filament-membrane-collagen fiber associations has been modeled based on ultrastructural data, and force trajectories at the junction have thereby been established. Measurements show that in healthy twitch cells, actin filaments lie at a mean angle of 4.3° (standard deviation = 0.95°; 15 cells analyzed) to the plasma membrane. Calculations indicate that maximum isometric loading is seen by the junctional membrane almost entirely as a shear stress. In disuse-atrophied muscle cells, the mean angle between actin filaments and the membrane is 9.1° (standard deviation = 3.3°; 11 cells analyzed). The shear component of loading for the junctions of atrophied cells is only 1% less than that in healthy cells. The tensile component of the stress at atrophied junctions is more than doubled, however. These data are used to interpret patterns of myotendinous junction mechanical failure in terms of adhesive joint mechanics. An increased occurrence of failure of the atrophied junction is observed at physiological loads and can be attributed to a reduction of adhesive strength under increased tensile load component.
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  • 39
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    Cell Motility and the Cytoskeleton 3 (1983), S. 491-500 
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; oligomers ; transmembrane glycoprotein ; microvilli ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The organization of microvillus actin and its associated proteins have been investigated in sublines of mammary ascites tumors (MAT) with mobile (MAT-B1) and immobile (MAT-C1) cell surface receptors. Microvilli isolated from these sublines differ in morphology (branched for MAT-C1 versus unbranched for MAT-B1) and the presence of a 58,000-dalton polypeptide (58K). 58K is found associated with MAT-C1 microvilli, microvillar cytoskeletons obtained by nonionic detergent extractions, and microvillar membranes prepared under conditions which depolymerize actin microfilaments. By extraction with actin-stabilizing buffers (isotonic Triton-Mg-ATP) microvillar actin can be fractionated into four forms. About 40% of the actin is sedimented at low speed (7,500g, 15 min). The pellets contain microfilaments; actin and α-actinin are the predominant proteins. High-speed pellets from these low-speed supernates contain about 10% of the actin as a transmembrane complex with a cell surface glycoprotein (cytoskeleton-associated glycoprotein, [CAG] 75-80,000 daltons) in MAT-B1 cells or with CAG and 58K in MAT-C1 cells. Transmembrane complexes can be purified from MAT-B1 and MAT-C1 microvillar membranes in Triton-containing buffer by gel filtration or sucrose density gradient centrifugation. The presence of only CAG and actin in the MAT-B1 transmembrane complex strongly suggests the direct interaction of actin and a cell surface component. The high-speed supernates contain soluble actin. By gel filtration or rate-zonal sucrose density gradient centrifugation about 30% of the microvillar actin is found as small oligomers and about 10% as G-actin in this extraction buffer. We suggest that the actin-containing transmembrane complexes may serve as membrane-association sites for oligomeric actin segments and microfilaments and as initiation sites for actin polymerization.
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  • 40
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    Cell Motility and the Cytoskeleton 3 (1983), S. 535-543 
    ISSN: 0886-1544
    Keywords: actin-binding protein ; filamin ; HeLa cell HMWP ; myosin ; HeLa cells ; paracrystals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: HMWP (high molecular weight protein), a high molecular weight actin binding protein, was previously isolated from HeLa cells; its physical properties, amino acid composition, and intracellular localization indicated its homology with actinbinding protein and filamin [Weihing, 1982, 1983]. We now report the identification of HMWP in striated paracrystals. Purified HMWP is incubated at 25° C and subjected to negative staining with uranyl acetate. Examination by electron microscopy reveals long, striated paracrystals formed from filaments a few nanometers in diameter that lie parallel to the long axis of the paracrystal. At intervals of about 200 nm, the filaments are crossed by granular aggregates, accounting for the striated appearance. Treatment of the paracrystals with an affinity-purified antibody to HMWP decorates the filaments; such decorations are not observed if nonimmune goat IgG or phosphate-buffered saline are substituted for the antibody. Electron microscopic and electrophoretic analysis of paracrystals sedimented onto grids by centrifugation at 864 g reveals that the grids are covered with paracrystals and the major polypeptide present on grids centrifuged in parallel is HMWP. Taken together, these data indicate that the filaments of the paracrystals contain elongated molecules of HMWP. Additional experiments are needed to decide if the paracrystals from by self-association between HMWP molecules or by association with one or more of the minor polypeptides that remain in the purified HMWP.
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  • 41
    ISSN: 0886-1544
    Keywords: brain spectrin ; actin ; immunofluorescence ; peptide mapping ; protein phosphorylation ; syndeins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Membrane-associated mouse brain spectrin is a 972,000 Mr, 10.5S, (αβ)2 tetramer containing two ∼ 240,000 Mr subunits and two ∼ 235,000 Mr subunits. Two-dimensional [125I]tryptic peptide mapping indicates that these subunits share only limited and equivalent overlap with the α- and β-subunits of red blood cell (RBC) spectrin. Both the 220,000 Mr β-subunit of RBC spectrin and the 235,000 Mr β-subunit of brain spectrin are phosphorylated in the intact mouse. In vitro analysis suggests that both are phosphorylated by a cAMP-independent protein kinase. Antibodies against pure native mouse red blood cell spectrin cross-react with brain spectrin, and antibodies against pure brain spectrin cross-react with both the α-and β-subunits of mouse RBC spectrin. Both antibodies have been utilized to localize brain spectrin within distinct cellular entities of the mouse cerebellum. Granule cell neurons of the internal granule layer and Purkinje cell neurons demonstrated intense fluorscence of the cortical cytoplasm immediately adjacent to the plasma membrane and unstained nuclei, when either RBC or brain spectrin antibodies were utilized for staining. The molecular layer of the cerebellum stained only lightly, and oligodendrocytes and astrocytes appeared to have little fluorescence. Therefore, while brain is a tissue rich in nonerythroid spectrin, the concentration of these immunoreactive analogues is quite variable within distinct cellular entities of the cerebellum.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 545-551 
    ISSN: 0886-1544
    Keywords: vascular smooth muscle ; contraction ; cytochalasin D ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cylindrical segments of extraparenchymal pulmonary artery (essentially a preparation of smooth muscle with regard to contractile capability) were isolated from adult male rats. They were mounted in an isometric muscle bath in physiological salt solution (PSS) in an environment of 95% O2/ CO2. After allowing 1 h for equilibration, the maximum force generated by the tissue in response to a depolarizing solution was determined. After relaxation, vessels were incubated for 1 h in one of several concentrations of cytochalasin D (CD) (0.01, 0.05, 0.5, 1, 10 μg/ml) and the response to stimulation retested immediately after returning to PSS, and then at 30 minute intervals up to 2 h.CD inhibited the ability of vascular smooth muscle to generate force (contract) in a concentration-dependent manner. The inhibitory effect was reversible within a short period of time. Quantitative electron microscopic examination of these vessels suggested that CD disrupts the integrity of myofilaments, especially at sites of “dense bodies.” Our results indicate that a percentage of actin in smooth muscle cells is not permanently in the filamentous “F” form, but is part of the G:F actin system of the cell, labile to polymerization:depolymerization. The ability of smooth muscle cells to generate force could depend on the proper functioning of the F:G actin “treadmill”.
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  • 43
    ISSN: 0886-1544
    Keywords: platelet ; platelet adhesion ; cytoskeleton ; high voltage electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adhesion of platelets in vitro resulted in rapid polymerization of the amorphous cytoplasmic ground substance into an organized cytoskeletal superstructure. This cytoskeleton, characterized through the use of whole-mount and stereo (3-D), high-voltage microscopy in conjunction with morphometrics and cytochemistry, comprised four major size classes of filaments organized in distinctive zones. The central matrix, or granulomere, at the center of the cell mass, was an ill-defined meshwork of 80-100-Å filaments which enshrouded granules, dense bodies, and elements of the dense tubular system as identified through peroxidase cytochemistry. Demarcasting this central matrix was a trabecular zone containing 30-50, 80-100, and 150-170 Å filaments in an open and rigid-appearing lattice. Circumscribing the trabecular zone and extending to the margins of the hyalomere was the third region, the peripheral web, in which 70-Å filaments were arranged in a tight honeycomb lattice. This organizational pattern was retained in cytoskeletons prepared by Triton x-100 extraction of the adherent cells, and was observed in basally located cells of aggregates which formed subsequent to adhesion. Our observations are consistent with biochemical studies of cytoskeletons prepared from suspended platelets and suggest a contractile protein composition for the superstructure during adhesion.
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  • 44
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    Cell Motility and the Cytoskeleton 3 (1983), S. 623-633 
    ISSN: 0886-1544
    Keywords: spectrin ; ankyrin ; brain membranes ; spectrin subunits ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Further similarity between mammalian erythrocyte spectrin and pig brain spectrin has been demonstrated by (a) formation of hybrid molecules with brain α-chains and erythrocyte β-chains and by (b) identification of an ankyrin protein in brain membranes. Hybrid spectrin molecules prepared from brain α-chains and erythrocyte β-chains were visualized by low-angle rotary shadowing as double-stranded rods (dimers) 100 nM in length. 125I-labeled brain α-chain that was hybridized with erythrocyte β-subunit acquired ability to bind to ankyrin sites on erythrocyte membranes. 125I-labeled brain α-chain bound only to β-subunits of erythrocyte and brain spectrin following transfer of these polypeptides to nitrocellulose paper from sodium dodecyl sulfate (SDS) gels. Thus brain spectrin and mammalian erythrocyte spectrin have shared functional sites involved in association of their subunits. Additional evidence for similarity of brain and erythrocyte membranes is the finding of a 210,000 Mr membrane protein in brain that cross-reacts with erythrocyte ankyrin and has a water-soluble domain of 72,000 Mr that is produced by protease digestion. The 72,000 Mr domain of brain ankyrin has been isolated by affinity chromatography on erythrocyte spectrin-Sepharose, and was demonstrated to bind directly to erythrocyte and brain spectrin. The brain 72,000 Mr fragment has distinct peptide maps from the erythrocyte 72,000 Mr ankyrin fragment and thus is not a result of erythrocyte contamination.
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  • 45
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    Cell Motility and the Cytoskeleton 3 (1983), S. 649-655 
    ISSN: 0886-1544
    Keywords: axonal transport ; lymphocyte capping ; spectrin ; fodrin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fodrin is an actin/calmodulin-binding protein with similarities to spectrin (erythrocytes) and TW 260/240 (brush border). It is concentrated beneath the plasma membranes of neurons and other cells. We have observed translocations of fodrin in both neurons and lymphocytes. Newly synthesized, radiolabeled fodrin moves down axons at a maximum velocity (about 50 mm/day) that is slower than the most rapidly axonally transported proteins (group I). A portion of fodrin appears to move more slowly at velocities (1-10 mm/day) resembling those of actin and myosin (group IV) and tubulin and neurofilament proteins (group V). In lymphocytes, when certain surface antigens are induced by cross-linking agents to migrate to one pole of the cell and form a cap, fodrin redistributes beneath the membrane and forms a subcap. The movements of fodrin in lympohocyte capping and in the axonal transport of group IV polypeptides have certain similarities. In both cases, the redistribution of fodrin is accompanied by concomitant redistributions of actin, myosin, and calmodulin, and both processes proceed at similar velocities. We consider the possibilities that these two processes are related, both being driven by a submembrane force-generating system comprising in part actin, myosin, and fodrin, and that fodrin serves to link various organelles or proteins to this system.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 151-165 
    ISSN: 0886-1544
    Keywords: actin ; villin ; fluorescence ; energy transfer ; polymerization ; microfilament ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the Ca2+-dependent interactions of villin, a protein of the intestinal microvillar core, with actin by monitoring resonance energy tranfer between fluorescently labeled actin subunits. In the presence of elevated free Ca2+(∼20 μM), villin affects both the nucleation and the elongation phases of actin polymerization. Consistent with previous reports, villin stimulates the nucleation process and will form stable nuclei under depolymerization conditions. Compared to the control, the net rate of polymerization is slightly inhibited at low con-centrations of villin (villin/actin ∼ 1:400) but is stimulated at higher concentrations (villin/actin 〉 1:100). Villin also significantly increases the critical concentration of actin polymerization. Addition of either villin or villin-actin complexes induces depolymerization of preassembled actin filaments. This villin-induced depolymerization is reversible upon removal of free Ca2+ or upon the addition of phalloidin. The exchange of actin subunits at steady state is inhibited at low concentrations of villin (villin/actin ∼ 1:200) but is stimulated at higher concentrations (villin/actin ∼ 1:50). None of the above effects is observed at 〈 10-8 M free [Ca2+].
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    Cell Motility and the Cytoskeleton 3 (1983), S. 273-280 
    ISSN: 0886-1544
    Keywords: Chlamydomonas flagellar collars ; Chlamydomonas cell wall ; mating in Chlamydomonas ; cell wall proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagella of Chlamydomonas reinhardtii protrude through the cell wall via short, tunnel-like openings that are lined with 11 nm × 500 nm fibers arranged in parallel array. These cylindrical collections of fibers presumably permit free movement of the flagella within the cell wall. In this report electron-microscopic evidence is presented showing that during the initial stages of the mating reaction intact collars slip off of the ends of the flagella when cell wall loss occurs. Electrophoretic analysis of isolated collars reveals one major protein and several minor species.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 283-305 
    ISSN: 0886-1544
    Keywords: taxol ; microtubules ; intermediate filaments ; fibroblasts ; epithelial cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Taxol promotes microtubule (MT) assembly in vitro and induces the reorganization of the cytoskeleton into unusual MT arrays in cultured cells. The possibility that taxol also has an indirect effect on intermediate filaments (IF) was investigated. In baby hamster kidney (BHK-21) and human skin (ENSON) fibroblasts treated with 1-10 μM taxol for 1-24 h, the drug induces changes which are similar to those produced by colchicine. These include a loss of major cellular extensions, a redistribution of organelles to a perinuclear location, and an inhibition of locomotion. Saltatory particle movements are not inhibited, however. Ruffling and filopod formation continue, indicating that cells are viable up to 24 h.Polarized light microscopy of living fibroblasts treated with taxol reveals the presence of perinuclear birefringent material which has been examined by immunofluorescence. In control cells, IF and MT radiate from a juxtanuclear region and extend to the cell periphery. In taxol-treated cells, MT and IF are excluded from cell margins, forming large central bundles.In the epithelial cell lines PtK2 and PAM, the keratin system of IF does not become redistributed; in PtK2, however, a second fibroblastlike system of IF does become redistributed to a perinuclear position during taxol treatment.Ultrastructural analyses show that taxol-treated fibroblasts contain parallel arrays of cross-bridged MT-IF as well as bundles of MT exclusive of IF. Epithelial cells contain a predominance of IF-free MT bundles which are organized into hexagonally packed arrays. In these bundles MT frequently exhibit hooks or other incomplete MT profiles and are linked by filamentous material.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 363-366 
    ISSN: 0886-1544
    Keywords: erythrocyte ; membranes ; spectrin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Cell Motility and the Cytoskeleton 3 (1983), S. 463-483 
    ISSN: 0886-1544
    Keywords: intracellular matrix ; extracellular matrix ; covalently cross-linked matrix ; ε-(γ-glutamic) lysine bonds ; skeletal muscle ; titin ; covalently cross-linked collagen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When skeletal, cardiac, and smooth muscle is exhaustively extracted with a protein-unfolding reagent such as 6 M guanidine HCl and a disulfide-reducing reagent such as 5% β-mercaptoethanol, a tissue ghost remains intact and retains the characteristic shape and dimensions of the tissue before extraction. In the case of chicken pectoral muscle, the tissue ghost contains 1% of the original muscle proteins. Guanidine HCl extraction followed by collagenase treatment of glycerol-extracted chicken pectoral muscle releases a clean preparation of elongated structures containing 0.2% of the original protein and representing the covalently cross-linked remnants of the muscle fibers. The material of these muscle fiber ghosts extends throughout the interior of the cell. Antibodies raised against the tissue ghosts of smooth muscle cross-react with glycerol extracted skeletal myofibrils, forming a banding pattern which coincides with the banding pattern observed when myofibrils are reacted with antibodies against titin. Titin, a large and soluble protein found in skeletal muscle, cross-reacts with our antigizzard antibody. However, amino acid analysis of the muscle fiber ghosts indicates that titin cannot be the only subunit of the insoluble polymer, but that one or more proteins with a very high glycine and alanine content and a very low basic and acidic amino acid content must also form part of the covalently cross-linked matrix. The possibility is presented that this matrix may be the basis of the superthin 2-3-nm filaments which have been observed in a variety of cell types.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 93-103 
    ISSN: 0886-1544
    Keywords: bacterial motility ; flagella ; sheathed flagella ; complex flagella ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although bacterial flagellar sheaths were observed over 30 years ago, they may still be characterized as structures in search of a function. In addition to true sheaths, bacterial flagella may possess other adornments that cause an increase in the organelle's cross-sectional diameter. These “complex flagella” are sharply differentiated from sheathed flagella. Immunological and chemical distinctions have been found between flagellar sheaths, flagellar cores, and LPS layers inferred to be the sheath sensu stricto. Although complex flagella may serve as specific receptors for flagellotropic phages or in allowing for more efficient swimming in viscous environments, similar functions have not yet been attributed to true sheaths. It is postulated that flagellar sheaths may allow for specific interaction between a bacterium and a surface. In addition, there is a problem as to the relationship between a rapidly rotating flagellum and the sheath.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 261-271 
    ISSN: 0886-1544
    Keywords: chromosome movement ; meiosis ; spermatocytes ; prophase ; nuclear envelope ; aster ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Association of bivalent chromosomes with the astral centers and nuclear envelope was analyzed in crane-fly spermatocytes during the final hours of diakinesis. In contrast to other systems in which movement of chromosomes during diakinesis correlates with the clustering of bivalents near the astral centers, such clustering is not prevalent in crane-fly spermatocytes. Polarization indices of bivalents calculated 5 to 10 minutes before the end of diakinesis provided evidence for polarization of only a fraction of all bivalents. Similar results were obtained in a large number of fixed cells in which asters and chromosomes were preferentially stained. Ultrastructural analysis of cells in late diakinesis revealed significant contact between bivalents and the nuclear envelope in all 46 cells that were analyzed. The extent of contact in some cells was greater than in others. Sites of contact included the telomeric ends of bivalents, and in some cases the distribution of contact sites suggested the possible involvement of centromeres in chromosome-nuclear envelope association. The results are consistent with the hypothesis that a dynamic interaction between chromosomes and nuclear envelope may exist during late prophase, when the movement of chromosomes is known to occur.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 227-245 
    ISSN: 0886-1544
    Keywords: swarming ; gliding ; cooperative motility ; cell density effects ; pili ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The coordinated movement of many cells - a process called swarming - permits myxobacteria to spread rapidly over a surface. We have investigated the mechanism of swarming in Myxococcus xanthus by making time-lapse motion pictures and by measuring the dependence of cell movement and spreading rate on the concentration of cells. Motion pictures of spreading zones showed that spreading resulted from motility, not growth, and that a swarm spread outward by establishing a loose reticulum of cells, then later filling it in. The spreading rate of wildtype strains was found to be highly dependent on cell density, increasing about 8-fold as the cell density was increased from 2.5 to 200 units. Mutants swarmed if they possessed only the A-motile component (A+S-) or only the S-motile component (A-S+) of wild type (A+S+); their spreading rate increased with cell density but was always less than A+S+. Individual A+S+, A+S-, and A-S+ cells executed typical gliding movements and (when moving) progressed at approximately the same speed, as if A and S motility were different ways of engaging the same gliding machine. Photographic studies of an A-S+ strain showed that cells moved only if they were separated by less than approximately one cell length from each other. This provided further evidence that pili, which are present on A+S+ and A-S+ cells and which extend about one cell length, could be responsible for switching on movement in S-motile cells, and presumably in wild type as well.
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    Cell Motility and the Cytoskeleton 3 (1983) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 3 (1983), S. 367-373 
    ISSN: 0886-1544
    Keywords: lateral diffusion ; membranes ; photobleaching ; cytoskeleton ; cell contact ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lateral diffusion measurements, using the photobleaching techniques, have provided unique and quantitative data on the random translational motions of proteins and lipids of membranes. Proper interpretation of this body of data can yield new insight into the structure of biomembranes. A comparative review of the lateral diffusion of membrane components in artificial lipid bilayers and of the same components in natural membranes is presented to demonstrate the effects of protein concentration and peripheral constraints on lateral mobility. Recent data on the effects of cell-substrate and cell-cell contact on lateral diffusion are reviewed. Finally, some experimental perspectives are offered in terms of emerging biophysical and biological technology.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 247-259 
    ISSN: 0886-1544
    Keywords: spermatozoa ; Ciona ; axoneme ; quiescence ; twist ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A simple planar model of sliding can predict the amount of sliding required to form a certain degree of bend. The accuracy of this prediction relies on the assumptions that no twists occur in the axoneme and that no sliding occurs at the base. However, previous studies indicated that twists may occur.This paper explores a new method for quantitating and analyzing twists. Preliminary results using this method showed that there were twists. In order to control for possible artifacts due to fixation and other preparative procedures, the characteristic S-shaped quiescent state of Ciona spermatozoa was studied.Analyses of platinum replicas of those flagella in which this waveform is well preserved suggest that most, if not all, of the twists observed are due to the artifact of a curved shape settling onto a surface. Detailed analyses indicate that if twists do occur in quiescent sperm, they are probably less than 0.4 radian. Since axonemes are evidently easily twisted in rigor, and even after fixation, caution should be exercised in interpretation of axonemal twists.
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    Cell Motility and the Cytoskeleton 3 (1983) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 3 (1983), S. 333-347 
    ISSN: 0886-1544
    Keywords: Caenorhabditis elegans spermatozoa ; cell motility ; electron microscopy ; cell-substrate contact ; 2-nm filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The locomotion of C. elegans spermatozoa resembles, in many respects, the crawling movements of other eukaryotic cells. However, these sperm contain surprising little actin, which plays no apparent role in this cell's motility. Electron microscopy has revealed that crawling spermatozoa retain a strict morphological polarity so that the organelle-filled cell body is separated from the pseudopod by an array of cytoplasmic laminar membranes. When sperm crawl only the pseudopod contacts the substrate; the cell body is either pulled behind or carried on top of the rear portion of the pseudopod. Fingerlike projections which extend forward from the leading edge of the pseudopod initiate contact with the substrate. The underside of the pseudopod exhibits areas of close (40 nm separation) membrane-substrate association with intervening areas of wide (up to 300 nm) membrane-substrate gaps. The pseudopod cytoplasm contains 2-nm filaments but no filamentous actin has been observed. These 2-nm filaments were detected in thin sections of crawling cells and in negative-stained remnants of spermatozoa disrupted by either hypotonic buffer on Triton X-100. The filaments are found both free in the cytoplasm and closely associated with the cytoplasmic face of the plasma membrane and are usually oriented along the long axis of the cell. Neither the identity nor the function of these filaments has been established although their location and orientation suggest that they may be involved in generating propulsion.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 383-390 
    ISSN: 0886-1544
    Keywords: F-actin aggregates ; actin-membrane interactions ; transformed/normal cell coculture ; F-actin/tropomyosin interaction ; temperature-sensitive viral mutant ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations on the role of transformation-specific F-aggregates [Carley et al, 1981] in altering morphology, adhesion and intercellular interaction in transformed cells are reported here. The appearance and disappearance of membrane- and substrate-associated F-actin aggregates (MAG and SAG, respectively) are followed in a cell line temperature-sensitive for transformation. Since MAG structures also appear near the membrane in suspension cultures of transformed cells and in transformed cells in coculture with untransformed cells, they appear to function at cell-cell contacts. Unlike microfilament bundles in untransformed cells, MAG and SAG do not contain the F-actin regulatory protein tropomyosin. The lack of tropomyosin in these structures near the membrane is reminiscent of areas of an exceptionally active actin cytoskeleton usually associated with motile processes of the normal cell membrane. Such areas of membrane-cytoskeletal interaction may be involved in the aberrant cell-cell communication as well as the aggressive behavior often seen in transformed cells.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 419-429 
    ISSN: 0886-1544
    Keywords: microfilament-membrane attachments ; cell-cell contacts ; fascia adherens ; immunofluorescence microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: On the premise that the fascia adherens of cardiac muscle cell intercalated disk membranes is a structure that is closely homologous to the focal adhesions formed by fibroblasts, a fascia adherens preparation was isolated from chicken cardiac muscle, and was analyzed for its protein composition. A prominent 200-kilodalton (kd) protein was purified from the fascia preparation and shown to be antigenically unrelated to several previously characterized cytoskeletal proteins, including cardiac myosin and vinculin. With monospecific antibodies to the 200-kd protein, an identical or closely similar intracellular protein was shown to be associated with the focal adhesion plaques of fibroblasts.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 449-462 
    ISSN: 0886-1544
    Keywords: myofibril to sarcolemma attachment ; costamere ; spectrin ; actin ; intermediate filaments ; vinculin ; fibronectin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Localization of vinculin at the sarcolemma of striated muscle fibers defines an orthogonal lattice. The costameres of the lattice are the riblike bands of vinculin that run perpendicular to the long axis of the fiber, repeat in register with I bands of the subjacent myofibrils, and seem to couple the myofibril to the sarcolemma [Pardo et al 1982, 1983a]. The colocalization studies presented in this paper show that gamma actin, spectrin, and intermediate filament antigens are additional components of this lattice of costameres. In addition, the results show that gamma actin and spectrin are also components of the internal network of collars, first visualized with antibody to desmin [Granger and Lazarides, 1978], that connects the myofibrils to each other at the level of the Z line.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 485-489 
    ISSN: 0886-1544
    Keywords: cell motility ; myosin ; actin ; vesicle transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Myosin-coated spheres from 0.6 to 120 μm in diameter move in vitro on a substratum of polar arrays of actin cables derived from the alga Nitella. The force for this movement is provided by skeletal muscle myosin since it is ATP-dependent, and N-ethylmaleimide (NEM) inactivation of the myosin blocks movement. These observations demonstrate that attachment of myosin in a random orientation to structures will enable those structures to move along polar arrays of actin filaments.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 513-524 
    ISSN: 0886-1544
    Keywords: fertilization ; actin ; microfilaments ; sea urchin ; cell division ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sea urchin egg at fertilization is an ideal model in which to study actin-mediated surface activity. Electron microscopy of unfertilized eggs demonstrates the presence of thousands of well-arrayed short microvilli, which appear supported by cytochalasin-sensitive actin oligomers as detected with rhodamine-labeled phalloidin staining of permeabilized eggs. At insemination, the previously short microvilli elongate and cluster around the successful sperm during incorporation. Phalloidin staining demonstrates a tremendous recruitement of polymerized actin into the site of sperm incorporation, resulting in the formation of the fertilization cone. Fertilization of cytochalasin-treated eggs results in the normal activation of the metabolic and bioeletric events, but sperm incorporation does not occur since the localized actin assembly required for fertilization cone formation is precluded. After sperm incorporation, the entire fertilized surface is restructured, as a result of a massive polymerization of actin to produce a burst in microvillar elongation. Addition of cytochalasin to eggs immediately following sperm incorporation demonstrates the recruitment of actin assembly for the proper progression through the first cell cycle. During normal cell divison, the egg surface retains the long microvilli. The furrow which forms at cytokinesis does not appear as a unique new structure, but rather as a reorganization of the cortical microfilaments. Quantitative fluorescence microscopy argues against an increase in microfilaments during early cytokinesis. At the latest stages of cytokinesis, a thickening of the cortical actin is noted, which could possibly be interpreted as a contractile ring. A minor basal level of actin assembly with numerous nucleation sites in unfertilized eggs and a tremendous but localized assembly of microfilaments surrounding the sperm during incorporation, followed by a massive global microfilament assembly event to elongate the fertilized egg microvilli resulting later in the reorganization of these microfilaments to produce the forces necessary for cytokinesis, highlight the utility of the study of sea urchin eggs at fertilization for understanding actin-membrane interactions.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 21-30 
    ISSN: 0886-1544
    Keywords: platelets ; Triton-insoluble residue ; fibrinogen ; fibrin ; tubulin ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several proteins (eg, actin, myosin, and actin-binding protein) in the Tritoninsoluble residue of thrombin-stimulated platelets are important in the formation of cytoskeletal structures. Electrophoretic analyses have shown that unidentified protein bands of 68,000, 55,000, and 48-50,000 daltons are also present in larger amounts after thrombin stimulation. Since these molecular weights correspond roughly to those of the α, β, and γ chains of fibrin, and since fibrinogen is found in platelet α-granules, these bands were compared to those obtained when purified fibrinogen was treated with thrombin, exposed to 1% Triton X-100-5 mM EGTA, and the resultant Triton-insoluble residue sedimented. Identification of the 68,000-, 55,000-, and 48--50,000-dalton bands as fibrinogen derivatives was confirmed by identifying them in comigration studies and in autoradiographs of Triton-insoluble residues of platelets that were electrophoretically transferred to nitrocellulose paper and treated with antifibrinogen antibody and 125I-protein A. Furthermore, if the platelet suspension was treated with thrombin in the presence of calcium ions, protein bands characteristic of the action of Factor XIII on fibrin were observed, active platelet Factor XIII apparently having been made available by lysis of platelets during preparation. Making use of the electrophoretic properties of tubulin recently described by Best et al [1981], comigration studies using hog brain tubulin indicated that tubulin is not present in significant amounts in the Triton-insoluble residue of platelets as previously suggested. The identification of these proteins as fibrinogen derivatives does not demonstrate a physiological interaction between fibrin and the platelet cytoskeleton, since fibrin is Tritoninsoluble and can be pelleted even in the absence of platelet cytoskeletons.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 109-109 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 3 (1983), S. 349-361 
    ISSN: 0886-1544
    Keywords: myosin phosphorylation ; actin polymerization ; chemotactic factors ; leukocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes in the state of polymerization of actin and phosphorylation of myosin have been observed in polymorphonuclear leukocytes (PMNs) soon after the addition of the chemotactic peptide N-formylnorleucylleucylphenylalanine. At a time when the cells are observed to extend many ruffles or lamellipodia from their surface, the fraction of the cellular actin present in a monomeric form is decreased by about 25% as assayed by the ability of the G-actin to inhibit DNAase. These changes are temporally correlated with an increase in the staining by nitrobenzooxadiazole (NBD)-phallacidin, a probe that binds F-actin selectively. The NBD-phallacidin staining is observed in the surface ruffles. When the peptide concentration is decreased by addition of a tenfold excess of buffer, cells withdraw their surface ruffles and form blebs. These changes correlate with an increase in the G-actin levels detected with the DNAase inhibition assay. An increase in phosphorylation of the 20,000-dalton light chain of myosin is also observed in leukocytes stimulated by addition of chemotactic peptide. These observations of changes in cytoskeletal proteins of PMNs provide a beginning for further studies on the regulation of cell motility by chemotactic factors.
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    Cell Motility and the Cytoskeleton 3 (1983), S. 375-382 
    ISSN: 0886-1544
    Keywords: actin ; spectrin ; band 4.1 ; cytochalasins ; erythrocyte ; brain ; actin-membrane attachment ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A complex of proteins with properties similar to those of erythrocyte spectrinband 4.1-actin complex has been idientified in a preparation derived from bovine brain. The complex has an apparent sedimentation coefficient of about 26S, and contains brain spectrin (also called fodrin) and actin as major components. The actin in the complex is in the oligomeric form, which nucleates assembly of actin filaments that grow from the “barbed” end. The complex cross-links actin filaments, resulting in an increase in low-shear viscosity. Whether the complex contains a protein analogous to erythrocyte band 4.1 is not known. However, it can be demonstrated that brain spectrin has the capability to interact with band 4.1 in a way which increases its ability to cross-link actin filaments.
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    Gamete Research 7 (1983), S. 49-61 
    ISSN: 0148-7280
    Keywords: spermatozoa ; isolation ; Centrifugation ; Percoll ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A procedure using centrifugation in density gradients composed of Percoll was developed for isolation of spermatozoa from mammalian semen. To evaluate the technique, rabbit, human, or bovine semen was layered over continuous Percoll gradients ranging in density from 1.02 to 1.13 gm/ml and centrifuged at 1,500g for 45 min. After centrifugation, the seminal plasma remained above the gradient, whereas the spermatozoa and seminal particles were distributed within the gradient according to their buoyant densities. Unlike most washing techniques, no sperm pellet was formed; instead, the spermatozoa were concentrated into a compact band above the most dense layer of Percoll. The spermatozoa recovered from the gradient were easily resuspended by gentle techniques. Thus, the mechanical stress to the spermatozoa was minimized. Osmotic stress to the spermatozoa was also negligible as the Percoll gradients were isotonic throughout. Spermatozoa obtained by this technique possessed motility equivalent to that of spermatozoa in the unfractionated semen. Sperm suspensions recovered from the gradients contained less than 5% of the nonspermatozoal particles present in the original samples of unfractionated semen. Soluble seminal components were also efficiently removed from the spermatozoa. Thirty billion bovine spermatozoa could be fractionated on a single gradient without loss of effectiveness. Recovery of spermatozoa from these preparative separations averaged 80%. These results demonstrated that Percoll was a superior medium for efficient density gradient isolation of motile spermatozoa free of contamination by other seminal constituents.
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    Gamete Research 7 (1983), S. 155-160 
    ISSN: 0148-7280
    Keywords: meiosis induction ; mammalian fetal ovary ; glycoprotein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The concept of Byskov which hypothesizes a glycoprotein inducer of meiosis for the mammalian fetal ovary has been tested by examining the incorporation of the specific precursor 3H-fucose into the rete ovarii of day 14 mouse ovaries. Semiquantitation of grains in autoradiographs has documented a concentration over the rete ovarii which exceeded that over the oogonia, ovarian fibroblasts, or surface epithelia. These data support the concept that the cytoplasm of mouse rete ovarii is capable of synthesizing a glycoprotein that may be the meiosis-inducing substance.
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  • 70
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    Gamete Research 7 (1983), S. 133-144 
    ISSN: 0148-7280
    Keywords: metabolism ; ATP ; phospholipid ; glycolysis ; tricarboxylic acid cycle ; sea urchin sperm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: When the dry sperm of the sea urchin, Hemicentrotus pulcherrimus, were diluted 100 times in artificial sea water at 0°C and at 20°C, they became motile and the levels of ATP and creatine phosphate decreased rapidly. The level of ADP hardly changed, and the AMP level increased after the dilution. After the dilution, the respiratory rate at 2°C was almost one fifth that of 20°C. Both phospholipid and glycogen were used for the energy sources in sea urchin sperm. The level of phospholipid was 10-fold higher than that of glycogen in the dry sperm. The phospholipid level decreased after dilution at 20°C, though the level hardly changed at 0°C, suggesting that phospholipid was hardly metabolized the lower temperature. The level of α -glycerophosphate increased at 20°C after the dilution but did not change at 0°C. The level of glycogen decreased after the dilution, regardless of the temperature. The glycolysis was also activated after the dilution. Of the intermediates of the tricarboxylic acid cycle, the citrate concentration increased at 0°C and the malate concentration also increased at 0°C and especially strongly at 20°C.
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  • 71
    ISSN: 0148-7280
    Keywords: guinea pig ; capacitation ; acrosome reaction ; sperm-egg fusion ; dithiothreitol ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Capacitation of guinea pig spermatozoa in vitro was inhibited by the disulfide-reducing agent dithiothreitol (DTT). Even a brief treatment with DTT inhibited capacitation unless an oxidizing agent (glutathione disulfide) was present in the posttreatment medium. Precapacitated spermatozoa were unable to undergo the acrosome reaction in the presence of DTT, indicating that this reagent also blocks the acrosome reaction. Acrosome-reacted spermatozoa were incapable of attaching to and penetrating the zona pellucida in the presence of DTT. Even when acrosome-reacted spermatozoa were directly brought to the surface of zona-free eggs, they were unable to bind to and fuse with the egg plasma membrane so long as DTT was present in the medium. These observations suggest that the tertiary and quaternary structures of sperm surface proteins regulated by their thioldisulfide status are of critical importance in the physiology and function of spermatozoa preliminary to and in the process of fertilization.
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  • 72
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    Gamete Research 7 (1983), S. 169-177 
    ISSN: 0148-7280
    Keywords: porcine ; sperm ; adenylate cyclase ; phosphodiesterase ; female secretions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Adenylate cyclase activities were studied in porcine sperm in the presence and absence of Mn++ before and after incubation in vivo and in vitro. Incubation of sperm in vivo for 30 min increased the Mg++-stimulated adenylate cyclase activity from 35.1 pmoles cyclic AMP formed per mg protein per 10 min to 50.4 pmoles. The activity stimulated by Mg++ and Mn++ increased from 392 to 729 pmoles after 30 min of in vivo incubation. Activity after incubation in vivo for 120 min was not different from activity after 30 min. In vitro incubation of porcine sperm in Ca++-free Ringer-fructose resulted in no change, but incubation in oviductal and uterine flushings obtained from gilts soon after ovulation increased Mg++-stimulated activity by 24% and Mg++-+ Mn++-stimulated activity by 49%. In vitro incubations in preovulatory flushings plus follicular fluid or in bovine serum albumin also increased adenylate cyclase activity.
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  • 73
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    Gamete Research 7 (1983), S. 197-198 
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 74
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    Gamete Research 7 (1983), S. 197-198 
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 75
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    Gamete Research 7 (1983), S. 199-214 
    ISSN: 0148-7280
    Keywords: ultrastructure ; spermatozoa ; nucleus ; Bivalvia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Sperm ultrastructure and spermiogenesis of the three bivalve species Musculus discors, Nucula sulcata, and Dreissena polymorpha have been studied. During spermatid differentiation in Musculus discors and Nucula sulcata the nucleus attains an elongated rod-like shape. The spermatozoon from Nucula sulcata was found to have a cup-shaped acrosome and five mitochondria surrounding two centrioles in the middle piece. The spermatozoa from Musculus discors has a long complex acrosome. From the distal centriole striated processes extend and attach to the plasma membrane. The spermatozoon of the fresh water species Dreissena polymorpha agrees in all main features with those of other invertebrate groups with external fertilization. It is thus of the primitive type with barrel-shaped nucleus and four to five mitochondria1 spheres in the middle piece. The acrosome is a prominant, complex structure at the apex of the mature spermatozoon.A comparison of sperm ultrastructure among bivalves indicates that there is a certain correlation between the evolution of the elongated sperm nucleus and large, yolk-rich eggs. In species with an elongated sperm nucleus the increased egg size has often led to a lecithotrophic or direct development. The elongated nucleus is a slight modification of the primitive type. There is a great variation in acrosome structure among bivalve spermatozoa, reflecting diverging functional demands at fertilization of the eggs.
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  • 76
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    Gamete Research 7 (1983), S. 227-239 
    ISSN: 0148-7280
    Keywords: testis ; human ; spermatogenic cells ; two-dimensional electrophoresis ; marker proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Highly homogeneous populations of human pachytene spetmatocytes and round spermatids have been obtained from normal adult testis using unit gravity (STA-PUT) sedimentation. Contaminating Leydig cells have been removed by density centrifugation in discontinuous Percoll gradients to yield resultant germ cell purities of 90-95% for pachytene spermatocytes and 89-96% for round spermatids. The total cellular polypeptide composition of separated human germ cells has been analyzed by two-dimensional polyacrylamide gel electrophoresis to compare 1) human and mouse pachytene spermatocytes (species specificity), 2) samples of human spermatocytes obtained from different individuals (allo specificity), and 3) pachytene spermatocytes and round spermatids from the same patients (stage specificity). Mouse and human germ cells have been found to exhibit extensive homology, but identified marker proteins limited to human spermatocytes include a group of polypeptides at p45/5.9 as well as a protein at p67/5.2. Proteins unique to mouse germ cells include component p65/5.5. Comparisons between different preparations of human pachytene spermatocytes have revealed about 90% electrophoretic homology, but some striking allotypic variations have been noted including the proteins at p45/5.9. Finally, presumptive stage-specific spermatogenic cell markers have been identified including the p45/5.9 polypeptides that are present only in human spermatocytes. Although the physiological roles of particular marker proteins have not yet been determined, the present findings indicate that purified spermatogenic cell populations may be analyzed biochemically to identify constituents important in the regulation of sperm development in man.
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  • 77
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    Gamete Research 7 (1983), S. 289-297 
    ISSN: 0148-7280
    Keywords: spermatogenesis ; mitochondrial proteins ; epididymal spermatozoa ; mice ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mitochondria from ejaculated bovine spermatozoa contain a group of polypeptides ranging in molecular weights from 13,000 to 35,000 not found in other bovine or murine testicular mitochondria [Hecht and Bradley, 1981]. These proteins are present in the mitochondria isolated from both epididymal and ejaculated spermatozoa. To establish when during epididymal transport, spermiogenesis, and/or meiosis these proteins are synthesized, the synthesis intervals for the mitochondrial proteins from cauda epididymal spermatozoa were established following intratesticular injection of (35S)methionine. Mice were killed every third day over a 33-day period and cauda epididymal spermatozoa were fractionated into mitochondrial and head components. Radioactivity in each fraction was monitored by liquid scintillation counting. Maximal incorporation was observed during spermiogenesis, although substantial amounts of protein were synthesized during meiosis. Analysis of the mitochondrial polypeptides by gel electrophoresis revealed that many polypeptides such as the cysteine-rich structural protein of the mitochondrial capsule were synthesized over prolonged intervals of spermiogenesis and meiosis rather than in a brief specific time period. These results suggest that spermatozoal mitochondria are produced by a sequential substitution of new proteins into the differentiating mitochondria rather than the abrupt appearance of a new class of mitochondria during spermatogenesis.
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  • 78
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    Gamete Research 7 (1983), S. 299-307 
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cynomolgus monkeys (Macaca fascicularis) were immunized with porcine zonae pellucidae to assess the possible antifertility effects of the zona antibodies. Serum antibody titers were evaluated utilizing a rapid solid-phase radioimmunoassay. Six of twelve monkeys conceived 6 to 10 wk after vaccination. All monkeys reached maximal antiserum titers by the time of conception, although the six animals that did not conceive had considerably lower antibody titers. Further pregnancies did not occur until antibody level had declined markedly, 8 mo after last immunization. The menses of all but one of the remaining six monkeys were interrupted intermittently. Also, the usual midcycle elevated estradiol levels were absent for several cycles. Both menses and midcycle estradiol peaks were reestablished in all but one monkey 3 to 5 mo after the last booster was given. Two monkeys conceived when serum antibody levels dropped to one fourth of maximal, but both had a still birth. Histological observations showed accumulation of luteal tissue and massive atresia of small follicles at the end of the study (18 mo). We conclude that through heteroimmunization with porcine zona pellucida monkeys can become infertile and that this condition is reversible. Because the zona preparation used in this study appeared to contain traces of nonzona material, it was not possible to determine whether the menstrual irregularities and oocyte atresia that we observed were owing to immunological effects on the zona itself or to the production of antibodies against other ovarian components.
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  • 79
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    Gamete Research 7 (1983), S. 309-324 
    ISSN: 0148-7280
    Keywords: Teleost ; sperm ; membrane ; ultrastructure ; lectin-binding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The plasma membrane of spermatogenic cells of the teleost Xiphophorus helleri was examined ultrastructurally and cytochemically in order to characterize the temporal development of the membrane specializations characteristic of the mature spermatozoon. Mature sperm display a mosaic distribution of Concanavalin A and Ricinus comrnunis I binding sites; the anterior region of the head displays an intense binding that is not seen in other surface regions. This asymmetric binding is evident in early spermatids and the area of lectin binding appears associated with the plasma membrane overlying the nucleus. Transmission electron microscopy reveals that the plasma membrane over the anterior region of the head is characterized by an ordered glycocalyx and a tight adherence to the underlying nucleus. Additional membrane differentiations were revealed both in the midpiece region where a “submitochondrial net” is attached to the plasma membrane and at the base of the axoneme where the plasma membrane possesses a “collar-like” arrangement of circumferential rings. The possible functions of these differentiations, as well as their correlation to differentiations seen in sperm of other animal groups, are discussed.
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  • 80
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    Gamete Research 8 (1983), S. 183-197 
    ISSN: 0148-7280
    Keywords: acrosin ; proflavin-sepharose ; anti-acrosin antibodies ; rabbit ; fertilization inhibition ; immunoreproduction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rabbit acrosin was purified from detergent extract of epididymal spermatozoa by molecular-sieve Chormatography (Sephadex G-75) and Priflavin-Sepharose affinity chromatography. Affinity Purified rabbit acrosin (Specific activity = 63.7 U Per mg Protein) exhibited one major band (Mr = 36,000) on SDS-polyacrylamide-slab gel electrophoresis. Sheep werweantibodies, Preared against acid-glycerol-stabilized acrosin, were Fractionated sequentitally with 50 and 33% ammonium sulfate. Anti-acrosin immunoglobulins were specific for the acrosome as evidenced by indirect fluorescence lebeling, and they inhibited acrosin's proteolytic activity when essayed for their effect on fertilization invivo, antiacrosin-treated sperm produced the lowest persent fertility (7.1%) followed by preimmune y-globulins(69%), Krebs-ringer hosphate-glucose-serum(96.4%) Analysis of antibody-treated sperm revealed no significiant chang in their motility or agglutination patterns. Antiacrosin antibodies, therefore, can effectivily neutrlize acrosin and inhibit fertilization when placed at the site of sperm-egg interaction in vivo.
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  • 81
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    Gamete Research 8 (1983), S. 231-244 
    ISSN: 0148-7280
    Keywords: plains mouse ; sperm head ; hooks ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ultrastructure of the sperm head of the plains mouse, Pseudomys australis, and the effects of chemical treatments on the sperm head components has been investigated to determine the nature of the material in the hooks on the apical margine of the sperm head. Ultrastructural studies indicated that the dorsal hook contained nuclear, subacrosomal, and acrosomal material, whereas the two ventral hooks were largely composed of an extention of the subacrosomal material with two thin acrosomal projections at their base. Acrosomal material was dispersed by mild detergent treatment, where as the bulk of the material in the ventral hooks were generally found to be similar to the subacrosomal material in the dorsal hook in their resistance to the various chemical treatments. Treatment of sperm with NaOH or guanidine-hydrochloride and DTT revealed two layers of material in the ventral hooks.
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  • 82
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    Gamete Research 8 (1983), S. 255-265 
    ISSN: 0148-7280
    Keywords: antigens ; plasma membrane ; intracellular ; monoclonal antibodies ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Fluorescent antibody labeling techniques are frequently used to investigate the topography of antigens on spermatozoa. It is generally assumed that these procedures detect molecules only on the sperm surface but we now show that this assumption is not always valid. Using monoclonal antibodies that recognize either surface or internal antigens we demonstrate how spurious conclusions can be made, and we suggest simple procedures for assigning the position of an antigen to the cell surface or to an intracellular organelle. Antibodies against plasma membrane antigens should stain 100% of normal intact spermatozoa, but this proportion should be greatly reduced if the spermatozoa have previously been demembranated. If ≪ 100% of spermatozoa are stained but the proportion increases following permeabilization, then the possibility should be considered that the antigens are intracellular. We conclude that assignment of an antigen to a regional domain on the sperm surface using fluorescent antibody techniques should be validated by a demonstration that the antigen is actually located on the cell surface.
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  • 83
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    Gamete Research 8 (1983), S. 279-293 
    ISSN: 0148-7280
    Keywords: fertilization ; jelly coat ; species specificity ; sperm enzyme ; sea urchin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A species-specific factor capable of disersing the jelly coat surrounding eggs has been purified from sperm of the sea urchin, Anthocidaris crassisina. It does not exert its effect on the vitelline layer. The purification has been accomlished by a four-step procedure involving ammonium sulfate fractionation, gel filtration on Sepharose CL-4B, ion-exchange column chromatography on DEAE-cellulose, and affinity column chromatograhy on heparin-Seharose CL-6B. The isolated factor is homogenous in sodium dodecyl sulfate polyacrylamide gel electrohoresis in the presence or absence of β-mercatoethanol, estimated molecular weight being about 140,000.The jelly dispersion by the present factor is activated by CaCl2, and inhibited by KCl, MnCl2, EDTA, and EGTA, and by sulfated saccharides such as chondroitin sulfate A and C, heparin, and glucose-6-sulfate, Inorganic sulfated such as (NH4)2SO4 and Na2SO4 have no effect on jelly dispersion. This factor is heat-labile, its activity in 30 min at 50°C.The present factor is found also in the seminal Plasma, and released from sperm themselves by treatment with Triton X-100 .These results suggest that this factor is loosely bound to the serm surface. Although glycosidase and arylsulfatase activities are detectable in the seminal plasma, these enzyme activities are not detectable in the purified jelly disersing factor.Only trypsin and α chymotrysin among commercial enzymes tested dispersing activity is inhibited neither by trypsin inhibitors such as N-α-p-tosyl-L-lysine-chloromethyl ketone, soybean trypsin inhibitor, ovomucoid trypsin inhibitor, nor by chymotrypsin inhibitors such as L-1-tosylamide-2 pheny-ethylcholoromethyl ketone and chymostatin Participation of trysin-like and chymotrypsin-like enzymes in jelly dispersion seems unlikely.
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  • 84
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    Gamete Research 8 (1983), S. 309-323 
    ISSN: 0148-7280
    Keywords: spermatozoa ; Nematoda ; evolution ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The main features of the Nematode sperm cell are the absence of a flagellum and of an acrosome. Transition forms have never been described, as in other animal phyla also reaching the aflagellate condition, like Platyhelminths and Arthropods. The absence of the flagellum must be considered as a definitive acquisition in the group. In addition, centrioles have been demonstrated to be lacking in most cases. The absence of the acrosome is the second general feature of the Nematode sperm cell. Among other features, more or less common to the Nematodes, the most important and general is the presence in the cell periphery of spheroidal membranous vesicles, originated from the Golgi complex but not involved in fertilization or in the production of ascaridin granules. These are absent only in the Ascarid Aspiculuris and the Dorylaimiid Xiphinema, both kinds of sperm having a peculiar shape. These granules are possibly involved in cell motility. Some Nematode sperm have proteinaceous crystalline inclusions originated from the rough endoplasmic reticulum, called ascaridin granules, the role of which remains obscure. A third important feature is the absence of a nuclear envelope, characterizing all described Nematode spermatozoa, the only exception being the Enoplid Mesacanthion, which seems to be for this reason the most primitive model in the group. Other features are the reduced number, or total absence of, the chondriome, an amoeboid movement not owing to an actomyosin system and a dense halo of 10-nm filaments surrounding the perinuclear cytoplasm.In this apparently homogeneous picture, three main evolutionary steps can be recognized. The first one, represented by the primitive Enoploid Mesacanthion, is that of a sperm conserving the nuclear envelope, surrounded by a few mitochondria and many membranous vesicles. The second, the most typical of the group, present in high Enoplida, and in Rhabditida, Strongylida, Ascarida, Spimrida, Trichinellida, is that of roundish, amoeboid spermatozoa devoid of a nuclear envelope but containing mitochondria, membranous vesicles, filaments, microtubules, sometimes centrioles, and sometimes ascaridin granules. The third step is apparently a simplification of the second; in fact, in Tylenchida and Dorylaimiida, the sperm is devoid of membranous vesicles, while in Mononchida and Dioctophymatida it is devoid of mitochondria. Aspiculuris, also devoid of membranous vesicles and having a big mitochondrial derivative, can be assigned to the same level. Nematode sperm evolution does not seem therefore to be a progressive acquisition of new characters, but rather a radiation from an already perfect model of some further simplifications occurring in parallel in most of the orders.
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  • 85
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    Gamete Research 8 (1983), S. 357-370 
    ISSN: 0148-7280
    Keywords: chromatin ; sperm nucleus ; freeze-fracture of chromatin ; nuclear structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nuclei of mature mammalian spermatozoa contain a highly ordered, lamellar substructure, presumably constituting the nucleoprotein of the haploid chromosomal complement. With a view toward constructing a plausible model of chromatin packing in sperm, we have determined some of the quantitative parameters associated with these “nuclear lamellae” in rat spermatozoa. Epididymal sperm from white, Sprague-Dawley rats were examined by conventional sectioning methods, freeze fracture of fixed and unfixed specimens, and by whole mount replica techniques. Fixation and glycerolation did not significantly alter nuclear structure as seen by freeze fracture. Numerical data obtained from cross fractures of sperm heads indicate that the number of lamellae are quite constant at 10.4 ± 1.8 and that the linear measure of the lamellae is 7.2 ± 2.3 μm per cross fracture. The total area of cross fracture, assuming an elliptical profile is 2.3 k 0.7 μm2 and the thickness of the lamellae is 18.2 ± 3.5 nm with a range of 13.5 to 25.5 nm. An estimate of the total surface area of the nuclear lamellae could be made from measurements of projected nuclear area (from replicas and sections) as 173 ± 15 μm2. From these data and the known amount of DNA in the rat sperm nucleus, a model can be proposed for the organization of the nucleoprotein in these lamellar sheets. It is suggested that the chromatin is arranged in a coiled-coil configuration closely associated together in a side-by-side fashion and continuous in extent. Approximate calculations based on this simple model are within a factor of 2 or 3 of predicting the correct amount of DNA in the sperm nucleus.
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  • 86
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    Gamete Research 8 (1983), S. 385-394 
    ISSN: 0148-7280
    Keywords: species specific antibodies ; sperm surface ; hybridoma antibodies ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The species specificity of hybridoma antibodies to sperm surface antigens was studied. A collection of over 50 hybridoma antibodies that bind to the guinea pig sperm surface was tested for binding to mouse, rat, hamster, and human sperm by indirect immunofluorescence. None of the antibodies bind to mouse sperm. rat sperm, or human sperm. All but three of the antibodies also fail to bind to hamster sperm. AH-30, AH-31, and AH-1032, the three antibodies that crossreact with hamster sperm, show a different topographical localization on hamster sperm from that seen on guinea pig sperm. The three antibodies do not precipitate a 125I surface-labeled antigen from hamster sperm extracts. However, from guinea pig sperm extracts, all three antibodies precipitate 125I surface-labeled polypeptides with molecular weights (Mr) of 62,000, 52,000, and 38,000. This result suggests that the crossreacting antibodies may be recognizing different antigens on hamster and guinea pig sperm.
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  • 87
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    Liebigs Annalen 1983 (1983), S. 535-556 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclitol Reactions, VIII. - Synthesis of Enantiomerically Pure (+)-Lycoricidine from D-GlucoseThe synthesis of enantiomerically pure (+)-lycoricidine (1) from D-glucose is described. The key reaction step is the addition of the aromatic anion 31 to the nitroolefin sugar 18 which gives the branched-chain sugars 32 and 33. After liberation of the aldehyde function of 32 and intramolecular aldol addition, 32 yields the lacton 35, a branched-chain nitroinositol with muco configuration. Reduction of the nitro group yields the amine 38 and rearrangement the lactam 40. Selective benzoylation to 43 followed by dehydration gives 47 which allows deblocking to (+)-lycoricidine (1). (+)-Lycoricidine (1) and its triacetate 49 are identical with the natural product.
    Notes: Die Synthese von enantiomerenreinem (+)-Lycoricidin (1) aus D-Glucose wird beschrieben. Der Schlüsselschritt der Reaktionsfolge ist die Addition des aromatischen Anions 31 an den Nitroolefin-Zucker 18, der zu den verzweigten Nitrozuckern 32 und 33 führt. Durch intramolekulare Aldolreaktion ist nach Freisetzung der Aldehydgruppe in 32 über 34 das Lacton 35 erhältlich, das einen verzweigten Nitroinosit der muco-Konfiguration enthält. Die Reduktion der Nitrogruppe in 35 führt zur Aminoverbindung 38, deren Lactongruppierung in das Lactam 40 umgelagert werden kann. Das aus 40 durch selektive Benzoylierung erhältliche Tribenzoat 43 ergibt durch Eliminierung von Wasser das Derivat 47, aus dem freies (+)-Lycoricidin (1) gewonnen werden kann. (+)-Lycoricidin (1) und dessen Triacetat 49 sind mit dem Naturprodukt identisch.
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  • 88
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    Liebigs Annalen 1983 (1983), S. 575-584 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminonucleosides, XI. - Bis(trimethy ammonio) Derivatives of AdenosineA five-step reaction starting from the aminonucleosides 1a or 1b yields the bis(trimethylammonio) derivatives 3′-trimethylammonio-6-[3-(trimethylammonio)propylamino]-3′-deoxyadenosine (8a) and 5′-trimethylammonio-6-[2-(trimethylammonio)ethylamino]-5′-deoxyadenosine (8b), respectively. The new compounds are biologically active and have muscle relaxing properties.
    Notes: Ausgehend von den Aminonucleosiden 1a und 1b wird in einer Fünf-Stufen-Reaktion die Synthese der Bis(trimethylammonio)-Derivate 3′-Trimethylammonio-6-[-3-(trimethylammonio)propylamino]-3′-desoxyadenosin (8a) und 5′-Trimethylammonio-6-[2-(trimethylammonio)ethylamino]-5′-desoxy-adenosin (8b) beschrieben. Die neuen Verbindungen sind biologisch aktiv und besitzen muskel-relaxierende Eigenschaften.
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  • 89
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Acylaminobromomalonates and Acylaminobromoacetates with Trialkylphosphites - A Simple Synthesis of Ethyl 2-Amino-2-(diethoxyphosphoryl)acetateDepending on the reaction conditions acylaminobromomalonates 1 and trialkylphosphites yield either 5-alkoxyoxazoles 7, 2-[acyl(dialkoxyphosphoryl)amino]malonates 8, or 2-acylamino-2-(dialkoxyphosphoryl)malonates 2. N-Acylglycin esters 9 can be converted into the corresponding α-bromo derivatives 10 by treatment with bromine or N-bromosuccinimide. Treatment of 10 with trialkylphosphites yields 2-acylamino-2-(dialkoxyphosphoryl)acetates 12. Removal of the protecting groups from the Boc or trichloroethoxycarbonyl derivatives 12g and 12h, respectively, leads to ethyl 2-amino-2-(diethoxyphosphoryl)acetate (11). Reaction of 10a with triphenylphosphane yields the phosphonium salt 14a which is converted into the 2,3-bis(benzoylamino)fumarate 18 by action of base.
    Notes: In Abhängigkeit von den Reaktionsbedingungen liefern Acylaminobrommalonester 1 mit Trialkylphosphiten entweder 5-Alkoxyoxazole 7, 2-[Acyl(dialkoxyphosphoryl)amino]malonester 8 oder 2-Acylamino-2-(dialkoxyphosphoryl)malonester 2. N-Acylglycinester 9 können mit Brom oder N-Bromsuccinimid in die α-Bromderivate 10 übergeführt werden, die mit Trialkylphosphiten glatt die 2-Acylamino-2-(dialkoxyphosphoryl)essigester 12 ergeben. Durch Entfernen der Schutzgruppen aus den Boc- und Trichlorethoxycarbonyl-Derivaten 12g und 12h ist 2-Amino-2-(diethoxyphosphoryl)essigsäure-ethylester (11) zugänglich. Das durch Umsetzung von 10a mit Triphenylphosphan erhältliche Phosphoniumsalz 14a erleidet bei Baseneinwirkung eine Dimerisierung zum 2,3-(Bisbenzoylamino)fumarat 18.
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  • 90
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Peroxides, XXV. - The Reactivity of Benzylic Methyl Groups at the Barton Type Cyclization of Organic HydroperoxidesOn the earlier reported cyclization conditions [lead(IV) acetate, n-pentane, cyclization apparatus] the hydroperoxides 1a-d yield the 2,3-dioxabenzocyclooctenes 3a, 3b and 2,3-dioxabenzocyclononenes 3c, 3d as well as the 1,2-dioxolanes 4a, 4b and 1,2-dioxanes 4c, 4d, respectively. Starting from the hydroperoxide 2 the 1,2-dioxolane 7 is the only cyclic peroxide obtained. The symmetric and the unsymmetric dialkyl peroxides 5, 6, 8, and 9 are obtained in all cases. - On the reaction of the hydroperoxides 1a, 1c, and 1d in acetic acid the cyclization is reduced to a very small extent. the symmetric dialkyl peroxides 5a, 5c, and 5d and the alkyl methyl peroxides 10a, 10c, and 10d are obtained in low yields. - The relatively high yields of the peroxides 3 are discussed on the basis of stereo-electronic effects.
    Notes: Unter den früher angegebenen Cyclisierungsbedingungen [Blei(IV)-acetat, n-Pentan, Cyclisierungsapparatur] ergeben die Hydroperoxide 1a - d die 2,3-Dioxobenzocyclooctene 3a, 3b und 2,3-Dioxabenzocyclononene 3c, 3d sowie die 1,2-Dioxotane 4a, 4b und 1,2-Dioxane 4c, 4d. Das Hydroperoxid 2 ergibt als cyclisches Peroxid ausschließlich das 1,2-Dioxolan 7. Daneben werden symmetrische sowie unsymmetrische Dialkylperoxide (5, 6, 8, 9) erhalten. - Bei der Reaktion der Hydroperoxide 1a, 1c und 1d in Essigsäure wird die Cyclisierung fast vollständig zurückgedrängt; in geringen Mengen werden die symmetrischen Dialkylperoxide (5a, 5c, 5d) sowie auch (Alkyl)(methyl)peroxide (10a, 10c, 10d) nachgewiesen bzw. isoliert. - Die relativ hohen Ausbeuten an den Peroxiden 3 werden diskutiert und durch stereo-elektronische Effekte erklärt.
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  • 91
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep, Reversible Redox Systems, XXXIII. - Reversible Transformation of a [4]Radialene into a Cyclobutadiene by Electron Transfer in Four StepsTetrapyridylcyclobutane 1 forms with chloroformate after deprotonation the red [4]radialene derivative 2aREDc which is oxidized by AgBF4 to the blue “squaric acid” derivative 2aOXc ≡ REDa, possessing cyanine type structure. The radialene 2aREDc constitutes the lowest oxidation level of a four-step, reversible redox system which allows for the first time to carry out electrochemically the reversible transformation [4]radialene ⇄ cyclobutadiene (here: 2aOXa). The redox properties of the system 2a (〉N-CO2Et) are compared with that of 2b (〉N-Me). The influence of the pyridinium substituents on the redox potentials is estimated by comparison with the model compounds 5a and 5b. From the conversion 2aSEMa → 2aOXa + e an antiaromatization energy of ca. 12 kcal/mol = 50 kJ/mol is derived. This value and the method employed is compared with those in the literature. Finally, the redox properties of the related [4]radialenes 2a, 2b, 9, and 10 are discussed, covering a 3.50 V range of potentials.
    Notes: Aus Tetrapyridylcyclobutan 1 und Chlorameisensäureester entsteht unter Deprotonierung das rote [4]Radialenderivat 2aREDc, das sich mit AgBF4, zum blauen, cyaninartigen “Quadratsäure”. Derivat 2aOXc ≡ REDa oxidieren läßt. 2aREDc ist das Endglied eines vierstufigen, reversiblen Redoxsystems, mit dem erstmals die Umwandlung [4]Radialen ⇄ Cyclobutadien (hier 2aOXa) elektrochemisch möglich ist. Das Redoxverhalten des Systems 2a (〉N-CO2Et) wird mit dem von 2b (〉N-Me) verglichen. Durch Abschätzung des Einflusses der Pyridinium-Substituenten auf die Potentiallage anhand der Modelle 5a und 5b wird aus dem Übergang 2aSEMa → 2aOXa + e die Antiaromatisierungsenergie dieses Cyclobutadiens zu ca. 12 kcal/mol = 50 kJ/mol abgeschätzt. Dieser Wert und die angewandte Methode werden mit Literaturergebnissen verglichen. Schließlich wird das Redoxverhalten der verwandten Radialene 2a, 2b, 9 und 10 diskutiert, das einen Potentialbereich von 3.50 V umfaßt.
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 687-694 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conjugation in Macrocyclic Systems, XXXI. - Isomeric Naphtho[14]annulenes with 1,2- and 2,3-AnnellationFor the syntheses of naphtho[1,2-α][14]annulene (1) and naphtho[2,3-α][14]annulene (2) the 1,2- and 2,3-di(1-hexen-5-ynyl)naphthalenes 4 and 8, respectively, were prepared. Cyclisation of 4 and 8 by oxidative coupling yielded 5 and 9, respectively, the prototropic isomerisation of which led to 1 and 2, respectively. - On the basis of 1H NMR spectra structure 1B was assigned to 1 whereas the different annellation type 2A was proven for 2. 1B shows fairly strong diatropicity in the [14]annulene system; no evidence for diatropicity was found, however, for the 2,3-annellated isomer 2A.
    Notes: Zur Synthese von Naphtho[1,2-α][14]annulen (1) und Naphtho[2,3-α][14]annulene (2) wurden die 1,2- und 2,3-Di(1-hexen-5-inyl)naphthaline 4 und 8 dargestellt. Cyclisierung von 4 und 8 durch oxidative Kupplung ergab 5 bzw. 9, deren prototrope Isomerisierung zu 1 bzw. 2 dagegen die symmetrische Struktur 2A. 1B zeigt mäßig starke Diatropie im [14]Annulen-System, während für 2A keine Diatropie nachzuweisen ist.
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  • 93
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Trialkylsilyl Trifluoromethanesulfonates, II. - Synthesis of O-Alkyl-O-(trialkylsily1)ketene Acetals and 2-(Trialkylsilyl)carboxylatesAlkyl carboxylates 2 are silylated by trialkylsilyl triflates 1 in the presence of triethylamine (3) to yield ketene acetals 4. In reactions of the esters 6 mixtures of ketene acetals 7 and at the α-carbon silylated esters 8 are obtained. Ethanoic acid esters and lactones are doubly silylated to give the products 11, 12, and 15, respectively. Under suitable conditions silylation of the esters 10 gives rise to the 2-trimethylsilylethanoic acid esters 13. The thermodynamically more stable products are obtained. Product distributions depend on the structure of the esters and the silylating agents 1.
    Notes: Durch Silylierung mit Trialkylsilyltriflaten 1 in Gegenwart von Triethylamin (3) erhält man aus Carbonsäureestern 2 die Ketenacetale 4, die Ester 6 ergeben Gemische aus Ketenacetalen 7 und am α-Kohlenstoffatom silylierten Estern 8. Ethansäureester 10 und Lactone 14 werden durch 1/3 zweifach zu den Produkten 11, 12 bzw. 15 silyliert. Unter geeigneten Bedingungen können 2-(Trimethylsilyl)ethansäureester 13 aus den Estern 10 gewonnen werden. Es resultieren die thermodynamisch stabilen Produkte. Die Abhängigkeit der Produktverteilung von der Struktur der Reaktionspartner wird diskutiert.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1020-1030 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, VII. - Synthesis of Rotundiquinone and 2,3′-Bijuglone via Halogenated BinaphthyldiquinonesAn improved synthesis of the unsymmetric quinoid-quinoid cross-linked [2,3′-binaphthyl]diquinones rotundiquinone (3a) and 2,3′-bijuglone (3c) was achieved by demethylation followed by hydrogenolytic dehalogenation starting from the monobromo derivatives 14a and 14c. Synthesis and properties of some more halogenated bijuglones are described.
    Notes: Eine verbesserte Synthese der unsymmetrisch über die chinoiden Ringe verknüpften [2,3′-Binaphthyl]dichinone Rotundichinon (3a) und 2,3′-Bijuglon (3c) geht von den leicht zugänglichen Monobromderivaten 14a und 14c aus, die sich glatt entmethylieren und anschließend hydrogenolytisch enthalogenieren lassen. Synthesen und Eigenschaften weiterer halogenierter Bijuglone werden beschrieben.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1043-1046 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Attempts on N-Amination of AlkaloidsSpiro[cyclohexane-1,3′-oxaziridine] (1) and ephedrine (4) react with N-N-bond formation to give the cyclic hydrazine derivative 6. Compound 1 also reacts with the hydroxytetrahydropapaverine 9a with N-N-bond formation; the reaction product undergoes C-C-cleavage under the action of acid and forms the hydrazonium salt 10.
    Notes: Spiro[cyclohexan-1,3′-oxaziridin] (1) reagiert mit Ephedrin (4) unter N-N-Knüpfung zu dem cyclischen Hydrazinderivat 6. Das Hydroxytetrahydropapaverin 9a reagiert mit 1 ebenfalls glatt unter N-N-Knüpfung; das Reaktionsprodukt erleidet durch Säure unter C-C-Spaltung Umlagerung zum Hydrazoniumsalz 10.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1047-1072 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XLVII. - Synthesis of Tri- and Tetrasaccharide Sequences of N-Glycoproteins Including a β-D-Mannosidic LinkageThe trisaccharides α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) and α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) as well as the key tetrasaccharide α-D-Man-p-(1 → 3)-[α-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51), which are parts of the carbohydrate chain of N-glycoproteins, have been synthesized. In this case the most important reaction is the direct synthesis of a β-mannoside linkage of D-mannos with 2-acetamido-2-deoxy-D-glucose. This problem has been solved by coupling of the halide 10 with the hydroxy component 14 in the presence of silver silicate which leads to the disaccharide 17. The product 17 is the fundamental compound for building up more complexed oligosaccharides.
    Notes: Die im Kohlenhydrat-Teil von N-Glycoproteinen enthaltenen Trisaccharide α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) und α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) und das Schlüsseltetrasaccharid α-D-Man-p-(1 → 3)-[α-D-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51) wurden synthetisiert. Die wichtigste Reaktion ist hierbei die direkte Herstellung der β-D-mannosidischen Verknüpfung zwischen D-Mannose und 2-Acetamido-2-desoxy-D-glucose. Die Verknüpfung gelingt durch Umsetzung des Halogenids 10 und der Hydroxylkomponente 14 mit Hilfe des Silbersilicat-Verfahrens zum Disaccharid 17. Das Produkt 17 ist die Schlüsselsubstanz für alle weiteren Aufbaureaktionen zu höheren Oligosacchariden.
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  • 97
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding bacteria, XV. - Myxalamides A, B, C, and D, a Group o Homologous Antibiotics from Myxococcus xanthus Mx x12 (Myxobacterales)A new antibiotic complex, called myxalamides, was isolated from the cells of Myxococcus xanthus Mx x12 (GBF). After preliminary purification using florisil the myxalamides were separated by reversed-phase chromatography to give four components. The spectroscopic investigation of the main component, myxalamide B (1), revealed the structure of an alaninol amide with a highly unsaturated, branched fatty acid. The xyxalamides A (3), C(4) D(5) are amides of homologous fatty acids and alaninol.
    Notes: Aus den Zellen von Myxococcus xanthus Mx x12 (GBF) wurde ein neuer Antibiotika-Komplex, genannt Myxalamide, isoliert. Nach Vorreinigung an Florisil wurden die myxalamide durch chromatographie an einer Umkehrphase in vier Komponenten aufgetrennt. Die spektroskopische Untersuchung der Hauptkomponente, Myxalamid B (1), ergibt die Struktur eines Alaninolamids mit einer verzweigten, hohungesättigten Fettsäure. Die Myxalamide A (3), C(4) und D(5) sind Amide aus homologen Fettsäuren und Alaninol.
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  • 98
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Nitriles, LXVIII. - 4-Dicyanomethylene-1,4-Dihydropyrimidines and Pyrido [4,3-d]pyrimidine-8-carbonitriles from EnaminonitrilesReaction of “dimeric malononitrile” (1a) or 3-amino-2-cyano-crotononitrile (1b) with dimethyl-formamide dimethyl acetal gives the biscondensation products 2. Subsequent treatment of 2a with ammonia and 2b with primary aliphatic amines leads to 4-dicyanomethylene-1,4-dihydropyrimidines 3. There are several possible structures for the reaction products obtained from 2a and primary aliphatic and aromatic amines. The structure of the product from 2a and propylamine is confirmed by X-ray structure analysis as 5,6-dihydro-5-imino-6-propyl-4-(propylamino)pyrido[4,3-d] pyrimidine-8-carbonitrile (4c). Hydrolysis of 4 in acidic medium leads to the 5-oxo derivatives 5.
    Notes: Reaktion von “dimerem Malononitril” (1a) oder 3-Amino-2-cyancrotonsäurenitril (1b) mit Dimethylformamid-dimethylacetal ergibt die Biskondensationsprodukte 2. Die Umsetzung von 2a mit Ammoniak oder 2b mit primären aliphatischen Aminen führt zu 4-Dicyanmethylen-1,4-dihydropyrimidinen 3. Für die Reaktionsprodukte aus 2a mit primären aliphatischen und aromatischen Aminen sind mehrere isomere Strukturen möglich. Die Röntgenstrukturanalyse des Produktes von 2a mit Propylamin sichert die Struktur eines 5,6-Dihydro-5-imino-6-propyl-4-(propylamino)pyrido[4,3-d]pyrimidin-8-carbonitrils (4c). Saure Hydrolyse von 4 liefert die 5-Oxo-Derivate 5.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1116-1132 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Oxo- and α-Thioxothioamides from Methyl KetonesMixtures of α-(chloro)sulfenyl chlorides 5 and trisulfides 6 are obtained from the reaction of thionyl chloride with methyl ketones in the presence of pyridine. From these mixtures as well as from the pure trisulfides 6, with amines the α-oxothioamides 1-4 are formed with good yields. Thionation of the thioamides 1 and 2 yields the deeply coloured α-thioxothioamides 16 and 17, the structure of which has been especially characterized by X-ray structure analyses.
    Notes: Bei der Reaktion von Methylketonen mit Thionylchlorid in Gegenwart von Pyridin entstehen Gemische aus α-(Chlor)sulfenylchloriden 5 und Trisulfiden 6, die - ebenso wie die reinen Trisulfide 6 - mit Aminen hohe Ausbeuten an α-Oxothioamiden 1-4 liefern. - Schwefelung der Thioamide 1 und 2 ergibt die tieffarbigen α-Thioxothioamide 16 und 17, deren Struktur insbesondere durch Röntgenstrukturanalysen charakterisiert wird.
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  • 100
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Syntheses via Heterocyclic Intermediates, XVIII. - On the Enantioselective Synthesis of (2R)-Serines Starting with The Bis(lactim) Ether of Cyclo-(-L-Val-Gly)The lithiated bis(lactim) ether 8a furnishes with aldehydes and ketones in good yields the addition products 11 with (3R) configuration. The asymmetric inductions at C-3 of 11 (d.e. values) amount to more than 95% with ketones, with aldehydes they are somewhat smaller. With unsymmetrical ketones or aldehydes C-3′ also becomes a chiral center. For the (3R)-major diastereomers the „second induction“ at C-3′ varies from about 4 to about 87% (for benzaldehyde or isobutyraldehyde, respectively), preferably the (3R,3′S) epimers are formed. - Acid hydrolysis of 11 yields (besides methyl L-valinate) the (2R)-serine methyl esters 26. Their e.e. values correspond with the d.e. values of 11. - Dehydratation of 11 furnishes the „Hofmann olefins“ 32 and/or the „Saytzeff olefins“ 33 which can be transformed in various ways into optically active amino acids.
    Notes: Der lithiierte Bislactimether 8a liefert mit Aldehyden oder Ketonen in guten Ausbeuten die Produkte 11 mit (3R)-Konfiguration. Die asymmetrischen Induktionen an C-3 (d.-e.-Werte von 11) betragen bei Ketonen mehr als 95%, bei Aldehyden sind sie etwas geringer (Tabelle 1). Bei unsymmetrischen Ketonen oder Aldehyden wird auch C-3′ zu einem Chiralitätszentrum. Bei den (3R)-Hauptdiastereomeren betragen die „Zweitinduktionen“ an C-3′ ca.4 bis ca. 87% (z. B. Benzaldehyd oder Isobutyraldehyd); vorzugsweise entstehen die (3R,3′S)-Epimeren (Tabelle 1). - Bei der sauren Hydrolyse der Addukte 11 erhält man (neben Methyl-L-valinat) die (2R)-Serin-methyl-ester 26, deren e.-e.-Werte an C-2 der asymmetrischen Induktion an C-3 von 11 entsprechen. - Die Dehydratisierung von 11 führt zu den „Hofmann-Olefinen“ 32 und/oder den „Saytzeff-Olefinen“ 33, die verschiedenartig zu optisch aktiven Aminosäuren abwandelbar sind.
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