ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Life and Medical Sciences  (871)
  • Organic Chemistry  (695)
  • 1980-1984  (1,566)
  • 1982  (1,566)
Collection
Publisher
Years
  • 1980-1984  (1,566)
Year
  • 1
    ISSN: 0886-1544
    Keywords: actin ; cleavage ; fluorescein-labeled phalloidin ; microinjection ; phalloidin ; sand dollar eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Effects of microinjection of phalloidin on fertilization and cleavage of sand dollar (Clypeaster japonicus and Scaphechinus mirabilis) eggs were studied. The drug, previously injected into unfertilized eggs, showed no effect on the elevation of the fertilization membrane upon insemination up to an intracellular concentration of 50 μM. However, the movement of the egg pronucleus to the sperm pronucleus was inhibited and the fusion of pronuclei did not occur. The subsequent development no longer took place. When phalloidin was injected into fertilized eggs, the thickness of the cortical layer increased and the microvilli became conspicuous. Both nuclear division and cleavage were inhibited at the intracellular concentration of more than 20 μM, though the latter seemed to be more sensitive to phalloidin than the former.Fluorescein-labeled phalloidin (FL-phalloidin) was injected into eggs in order to investigate F-actin localization by fluorescence microscopy. In both unfertilized and fertilized eggs, FL-phalloidin was localized in the cortical layer within 1 min after injection. It was also localized in the cortical layer as radially oriented rodlike structures when injected into fertilized eggs before the disappearance of the nuclear membrane. No distinct fluorescence was detected in the mitotic apparatus or in the cleavage furrow. FL-phalloidin redistributed gradually into egg cytoplasm. In unfertilized eggs, fluorescent rods were found especially in the egg pronucleus 30 min after injection.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0886-1544
    Keywords: higher land plant contractile system ; actin activation of myosin ; S-1 decoration of actin ; polymerization of actin ; calcium sensitivity of actomyosin interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper describes the initial isolation of actin- and myosin-like proteins from the cytoplasm of the endocarp tissue cells of the fruit of the tomato, Lycopersicon esculentum. Low ionic strength buffers extracted the 42,000 molecular weight tomato actin in the depolymerized form. Tomato actin can be polymerized in 0.1 M KCl, 2 mM MgCl2 to form 6 nm diameter filaments resembling rabbit skeletal muscle F-actin in their ultrastructure and pattern of decoration with rabbit myosin subfragment-1 (S-1). Tomato F-actin activates the low ionic strength Mg2+ ATPase of rabbit S-1 up to ten-fold. High ionic strength extracts of tomato yield a myosinlike enzyme whose ATPase activity in 0.5 M KCl is maximal in the presence of K+-EDTA and is repressed in the presence of Mg2+. The column-purified enzyme forms a complex with rabbit F-actin, which can be dissociated by Mg2+ ATP. The low ionic strength Mg2+ ATPase of tomato myosin can be activated ten-fold by rabbit actin and up to nineteen-fold by tomato actin. No activation of the tomato myosin by rabbit F-actin occurs in the absence of free calcium ions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 333-341 
    ISSN: 0886-1544
    Keywords: cell motility ; collagen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The motility of an epithelial cell line NBT-II derived from a rat bladder tumor was examined on glass and on collagen. On glass the cells rotate in groups of 2-8 cells. Rotatory migration ceases as cells enter into mitosis; after mitosis, the daughter cells spread out and participate in the rotatory activity of the group. As the number of cells in a group increases the rate of rotatory migration slows, and groups with ten cells or more do not rotate consistently. On collagen NBT-II cells migrate as single cells in a smooth gliding fashion, with the broad lamellipodia as the leading front. After mitosis, the two daughter cells separate at 180° of each other and migrate away independently. Before totally spreading out on the collagen surface, the pair of daughter cells shows a characteristic twist of about 60° from their original position at telophase. The difference in motility of NBT II cells on glass and on collagen is explained in terms of differences in cell-to-cell cohesion and cell-to-substrate adhesion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0886-1544
    Keywords: cytoskeleton ; platelets ; actin-binding protein ; actin ; myosin ; thrombin activation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When human blood platelets were immersed in an ice-cold solution containing 1% Triton ×-1200, 40 mM KCl, 10 mM EGTA, 10 mM imidazole-HCl, and 2 mM NaN3 pH 7.0, a flocculent precipitate appeared immediately in the tube. This precipitate was collected at 3,000g and SDS-polyacrylamide gel analysis showed it to consist mainly of actin, α-actinin, actin-binding protein (ABP), and varying amounts of myosin.Any modifications of this solution used to isolate the platelets' Triton-insoluble cytoskeleton caused profound changes in the nature of the cytoskeleton isolated. Increasing the KCl concentration resulted in a lower yield of cytoskeletal actin and ABP. Inclusion of EDTA in the solution resulted in an increased amount of myosin associated with the cytoskeleton, whereas including MgATP decreased the myosin yield.Experiments with the purified proteins showed that ABP and myosin can each protect the actin from depolymerizing when dialyzed into the Triton solubilization solution. In addition, it was found that when platelets were stimulated with thrombin for 2 min prior to the addition of the Triton solution, 3-4 times more myosin was associated with the cytoskeletal precipitate.The results suggest, therefore, that any variations in solution conditions used for isolating the cytoskeleton from resting platelets, which results in alterations in the amount of ABP, may have profound effects on the state of actin polymerization. Likewise, in thrombin-activated platelets, it is suggested that the increased association of myosin with the cytoskeleton results in a greater stabilization of the F-actin associated with the cytoskeleton. These factors must be considered when interpreting the results regarding the nature of actin transformations in the resting and activated platelet.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0886-1544
    Keywords: proacrosome migration ; nuclear pore redistribution ; nuclear membrane fluidity ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microscopic examination of thin sections and freeze fractures of Locusta spermatids revealed that the proacrosome docks to the nuclear membrane and glides around the nucleus during sperm development. Whereas nuclear pore complexes occur in groups distributed at random over the entire nucleus of the early spermatid, they are found only in a narrow ring closely surrounding the centriolar adjunct in later spermatids. The pores appear to be swept caudally in the nuclear envelope, perhaps by a process like capping; they are not merely excluded by structures adhering to the nucleus. The observations suggest that both proacrosome migration and the deployment of pores are facilitated by the inherent fluidity of the nuclear membranes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0886-1544
    Keywords: NBD-phallacidin ; actin ; ocular tissues ; wound repair ; stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fluorescent derivative of the actin-binding toxin phallacidin, 7-nitrobenz-2-oxa-1,3 diazole phallacidin, has been used to cytologically demonstrate the presence of actin in lens epithelium, corneal endothelium, and retinal pigment epithelium. In these noninjured tissues, no stress fibers are observed and fluorescence is confined mainly to an area at or near the cell membrane, although some diffuse cytoplasmic staining can also be seen. However, following injury to either the lens epithelium or corneal endothelium of rats and frogs, stress fibers are detected, but only in those cells that migrate into the wound area. Cells on the periphery of each tissue do not partake in would repair and thus maintain their normal appearance. After the tissue has regenerated, stress fibers disappear, and those cells involved in the injury response return to their normal morphology.When rabbit corneal endothelium is placed in tissue culture, stress fibers are observed as the cells migrate away from the initial explant. Upon reaching confluency, these cells spread out and each is surrounded by thick actin-containing bands. Furthermore, they exhibit some stress cables within their cytoplasm. This is in contrast to their appearance in vivo where stress fibers are absent and fluorescence is limited to a region near the cell membrane.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 369-383 
    ISSN: 0886-1544
    Keywords: motility ; flagella ; cilia ; microtubules ; Gregarines ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male gametes of the parasitic protozoan, Lecudina tuzetae, have a motile flagellum with a “6 + O” ultrastructure ‘Schrével and Besse, 1975’. These gametes were isolated from the cysts in which they develop and were observed and photographed under a variety of conditions. The flagella beat continuously, without stopping and starting, with a beat period of about 2 sec. They can beat in solutions whose viscosities are greater than 0.5 Nsm-2 (l Nsm-2 = 103 cP). The waveform can be approximated by a series of helical arcs and interconnecting straight regions that travel from the base to the tip. The helical regions have a radius of curvature of 3.2 μm and subtend a final angle of 1.7 radians. The straight portions are 2.0 μm in length. There are two sets of opposing bends, but they do not originate in the same plane. The resulting waveform is an approximately helical coil, with a pitch of 9.8 μm, a pitch angle of 0.6 radian and a peak-to-peak amplitude of 2.3 μm. The sense of the coil is left handed. The axoneme twists during beating. The main differences between the movement of this flagellum and that of typical 9 + 2 flagella are a low beat frequency and three-dimensional bends that produce relatively little forward movement of the cell. Twisting is discussed as a means of discriminating between some types of models of flagellar motility.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 393-403 
    ISSN: 0886-1544
    Keywords: motility ; Ca2+ ; ionophores ; spirulina subsalsa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility of the marine filamentous cyanobacterium Spirulina subsalsa is both Ca2+ and Na+ dependent, and replacement of Na+ by mannitol arrests it. The data presented suggest that Ca2+ interacts with sites on the surface of the cell membrane. The inhibitory effect of dicyclohexylcarbodiimide (DCCD) hints at the possibility that the role of Ca2+ may be associated with a membrane bound Ca-ATPase. Motility is pH dependent, being nil at pH 〈 6.5 and 〉 10.0, with an optimum at 8.5. Norepinephrine abolishes most of the inhibitory effect of low pH on motility. Ca2+ has an “all-or-none” effect on motility that is triggered at 5 mM. Acetylcholine lowers the threshold of Ca2+ necessary for triggering motility.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 0886-1544
    Keywords: ciliated cell ; basal body apparatus ; microtubules ; microfilaments ; respiratory epithelium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This is a descriptive study showing the three-dimensional interrelationship of cytoskeletal elements at the apex of ciliated cells of rat respiratory epithelium. Tissue specimens were serially thin sectioned in various planes and examined by transmission electron microscopy. Thicker sections were also cut at various angles and analyzed stereoscopically. Other specimens were cleared of soluble molecules by glycerination or Triton-X 100 treatment and sectioned as described above. It was found that C microtubules from the triplets of each basal body diverge from the A and B microtubules, run a short distance, and converge at the basal foot. These microtubules or other microtubules arising anew then dispersed deeper into the cytoplasm. The C fibers also interdigitated with other microtubules running perpendicular to them and parallel to the ciliated surface. Ten-nanometer intermediate filaments were organized in parallel sheets between adjacent basal bodies. Sixnanometer actin filaments were distributed throughout the apical cytoplasm. Neighboring basal bodies were linked to one another by microtubules and microfilaments. Basal bodies from each cell appear to be structured for stability, flexibility, and arranged to operate as a single unit.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 0886-1544
    Keywords: calmodulin ; myosin ; antibody ; immunofluorescence ; amoeba ; Dictyostelium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A rabbit antiserum was raised against calmodulin from the eukaryotic microorganism Dictyostelium discoideum. In double immunodiffusion experiments, the antiserum formed an immunoprecipitation line with Dictyostelium calmodulin but not bovine brain calmodulin; competition radioimmunoassays showed no cross reactivity between the antiserum and calmodulins from bovine brain and spinach. The calmodulin content of vegetative Dictyostelium amoebae, determined by competition radioimmunoassay, was 0.5 μg/mg protein; similar levels were found in developing cells. The antiserum was used to visualize the distribution of calmodulin in Dictyostelium amoebae by indirect immunofluorescence. Cells were examined under various conditions: in suspension, attached to a substrate, and while phagocytosing yeast cells. In all cases, anticalmodulin staining was concentrated in the cell cortex. Parallel experiments using a monoclonal antibody against Dictyostelium myosin showed that this protein is also enriched in the cortical region of the cell.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 483-496 
    ISSN: 0886-1544
    Keywords: Cilia ; Ca ; motor control ; ciliates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied quantitative aspects of ciliary motor responses to membrane depolarization in the ciliate Stylonychia using voltage clamp and high-speed cinematograhpy techniques and employing computer-processing methods for evaluation. Depolarizations beyond 4 mV activate the cirri (compound cilia) which are at rest in the absence of a stimulus. The power stroke of activiated cirri is oriented toward the cell anterior. The frequency and duration of beating increase with rising depolarization. With very large positive stimuli (≥ 150 mV) activation of the response is delayed until the end of the voltage step (“off-response”). The peak frequecy is essentially unaltered during sustained depolarization. The frequency drops exponentially following repolarization of the membrane. The time constant of the decay in ciliary activity rises with the amplitude, not with the duration of the depolarization. The ciliary motor response is most adequately represented by the number of evoked ciliary cycles (ciliary work), and appears to be related to the amplitude of the depolarization.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 0886-1544
    Keywords: cilia ; electric motor control ; ciliates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied the motor responses to membrane hyperpolarization of the marginal cirri in Stylonychia using voltage-clamp, high-speed cinematography, and computer-processing techniques. The cirri started beating when voltage step amplitudes rose beyond 5 mV. The power stroke was oriented toward the posterior cell and (hyperpolarizing motor activation). The frequency rose slightly during a voltage step, and decreased with similar rates for 100 ms following the step end. Amplitude and duration of the step tended to increase the motor response of the cirri. The late response declined exponentially. The time constant of the decay rose with the step amplitude. Among three response parameters tested (frequency, duration, number of cycles), the number of evoked ciliary cycles was best correlated with the amplitude of the hyperpolarization. Comparisons with the responses to depolarizing voltage steps reveal similarities in the relaxation of ciliary activity which appears to be uncoupled, in part, from the electric membrane events during the voltage stimulus.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 0886-1544
    Keywords: cations ; cilia ; dynein ; ATPase ; microtubule sliding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We recently demonstrated that elevated concentrations (≥ 20 μM) of the dynein substrate MgATP2- inhibit the spontaneous ATP-induced sliding disintegration of isolated, Triton-demembranted Tetrahymena cilia. We have used a turbidimetric assay (ΔA350 nm) and electron microscopy to examine the effect of ATP on sliding disintegration when activated by other divalent cations. Mg2+, Ca2+, and Mn2+ are each capable of activating sliding, but only with Mg2+ and Mn2+ is disintegration inhibited by elevated ATP concentrations (≥ 1 mM). The two major ATPase activities obtained by KCI extraction of Tetrahymena axonemes differ in their cation specificities such that Mg2+ and Ca2+ activate the 21S dynein ATPase with equal efficiency, whereas the 13S axonemal ATPase activity is reduced by ∼ 50% when CaATP2- replaces MgATP2- as substrate. With 1 mM MgATP2- as substrate, 10-7 to 10-2M added CaC12 alleviates the ATP-dependent inhibition of disintegration and likewise represses 13S MgATPase activity. In contrast, free Ca2+ has no effect on either the disintegration response or MgATPase activity. In contrast to Triton-treated cilia, glycerinated cilia, which beat in 1 mM MgATP2-, are inhibited from beating by high CaATP2- concentrations. These substrate specificities suggest that concentration-dependent, substrate inhibition of sliding disintegration may be a manifestation of a physiological mechanism that is mediated by the 13S axonemal ATPase and that may function to modulate sliding during bend formation. However, the effects of added CaCl2 probably do not reflect a physiological mechanism for regulating beat parameters, but rather may result from CaATP2- competing for MgATP2- binding sites on the 13S ATPase, thereby blocking expression of the 13S ATPase.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 583-597 
    ISSN: 0886-1544
    Keywords: endocytic vesicles ; microtubules ; 10-nm filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ligand binding to cell surface receptors induces rapid internalization of ligandreceptor complexes by receptor mediated endocytosis. We have examined the intracellular movement of endocytic vesicles, induced by the lectin concanavalin A (Con A), in cultured rat ovarian granulosa cells using fluorescence and electron microscopy. Within 20 minutes of ligand treatment at 37°C, numerous Con A-containing endocytic vesicles form, which migrate to the cell center by 60 minutes. Double label fluorescence microscopy, using fluorescien-Con-A and rhodamine immunofluorescent staining of tubulin or vimentin, indicates that during vesicle migration microtubules and 10-nm filaments are altered in their organization. By 30 minutes, vesicles are associated with microtubule bundles, which subsequently collapse around the nucleus. Similarly, 10-nm filaments accumulate around the nucleus in conjunction with the perinuclear aggregation of endocytic vesicles. Electron microscopy of Con A-horseradish peroxidase-labeled cells demonstrates that endocytic vesicles fuse to form large receptosome-like structures during intracellular migration and these structures are associated with cytoplasmic microtubules and 10-nm filaments. Taxol, a drug that stabilizes microtubules, prevents endocytic vesicle translocation to the Golgi region. Nocodazole, which causes microtubule disassembly, results in the collapse of 10-nm filaments and the central aggregation of endocytic vesicles. The data indicate that the cytoskeleton participates in the directed intracellular movement of endocytic vesicles; the possible subcellular basis for this movement is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 121-126 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 133-136 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 185-189 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 191-194 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 195-198 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 211-215 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 217-224 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 225-228 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 0886-1544
    Keywords: microfilaments ; F-actin ; brain actin-depolymerizing factor ; tropomyosin stabilization of microfilaments ; DNase I inhibition assay ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Brain or muscle F-actin is rapidly depolymerized to monomeric actin in vitro by actin-depolymerizing factor, a protein isolated from chick embryo brain. Binding of muscle tropomyosin to muscle F-actin protects the F-actin from depolymerization by this factor. A 8.4/1.0 molar ratio of actin subunits to tropomyosin, achieved by incubation of the F-actin with excess tropomyosin, protects 58% of the F-actin from depolymerization by excess actin-depolymerizing factor for at least 3 hr at 25°C. Thus, actin-depolymerizing factor seems to be specifically directed toward actin filaments lacking tropomyosin.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 0886-1544
    Keywords: amoebae ; actinopoda ; heliozoa ; Actinophrys ; phagocytosis ; pseudopodia ; membrane ; extrusomes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two phases of prey capture by the heliozoon Actinophrys sol are documented by electron microscopy. The phases are those of prey adhesion to the predator and enclosure of the prey by the predator. Adherence is brought about by numerous small pieces of adhesive membrane produced by the predator at the site of prey contact. Some of the heliozoan extrusomes expel their contents at this time, but the significance of this event is unclear. Enclosure of the prey is effected by a funnelshaped pseudopodium. This is drawn over the prey by the action of the leading margin. The ultrastructural appearance of the cytoplasm of the leading margin differs from the rest of the cell, being homogeneous and finely filamentous. Both force and traction for the progression of the pseudopod are generated primarily at the tip. During the development of the funnel-pseudopod, extrusomes expand and fuse with each other and with the plasma membrane. Their investing membrane is thereby made available as food vacuole membrane.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 0886-1544
    Keywords: cell migration ; epithelial cell culture ; 2-deoxyglucose ; glycolysis ; microtrabecular lattice ; ATP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using a line of epithelial cells (SCCA5) derived from a spontaneous rat carcinoma, the glucose analogue 2-deoxyglucose (2DG) has been shown by time-lapse cinemicrography to produce a cessation of motility by 1 hour that can be reversed by replacement of the 2DG, and does not occur in equivalent media with or without glucose or in 2DG-containing media with added pyruvate and citrate. The effect on the cells at the edge of an epithelial island is to prevent the formation of new lamellipodia and produce a progressive retraction and condensation of lamellipodia already present. This effect of 2DG on motility corresponds with a significant reduction in the level of ATP that is partially restored after 30 minutes in the recovery incubation. Only a slight reduction in protein synthesis occurs in the presence of 2DG. The external morphology and the cytoplasmic ground substance of the cells were studied by scanning electron microscopy and high voltage electron microscopy respectively. It was found that after incubation in 2DG for 1 hour the outline of the free edges of the cells was distorted resulting in redistribution of microvilli, condensation of cytoplasm into strands, and irregular projections from the edges of residual lamellipodia. The structure of the cytoplasmic ground substance in lamellipodia from cells incubated in 2DG for 3 hours was distinctly different from that in cells incubated for 3 hours in 2DG then recovered for 25 minutes, or in cells incubated in glucose-containing medium for 3 hours. In the 2DG-treated cells the lattice-like structure evident in critical-point-dried cells was condensed into short thick strands that terminated in bulbous ends, whereas in cells recovered for 25 minutes the lattice material was elongated and tapering and the interlattice space relatively expanded. The results obtained support the concept of modulation occuring in the structure of the microtrabecular lattice component of the cytoplasmic ground substance coincident with alterations in cell function and metabolic state.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 83-89 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 0886-1544
    Keywords: microtubules ; transport ; secretion ; peritrich ciliate ; directional turnover ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of microtubules in secretory granule translocation was studied during stalk secretion in the peritrich ciliate, Zoothamnium arbuscula. In each cell, the release of stalk-forming secretory materials is restricted to a specialized region of the cytoplasm, the scopula. Many of the membrane-bound secretory granules that dominate the scopular cytoplasm appear to be aligned along cortical microtubules that converge on the scopular surface. This arrangement is consistent with the hypothesis that microtubules transport granules relative to the sites of exocytosis. To establish the role of microtubules in stalk secretion, telotrochs were exposed to agents with different disruptive effects on microtubule function. Exocytosis itself is not prevented by these drugs, and granules positioned for secretion prior to treatment are released. Maytansine and isopropyl-n-phenyl carbamate (IPC) completely inhibit stalk elongation. In maytansine-treated cells, microtubules are absent from the scopular cytoplasm, and granules are absent from the scopular surface. Microtubules are present in IPC-treated cells, but the granules are misdirected to the cytoplasm lateral to the scopula where no secretory sites exist. Even though the rate of stalk secretion is decreased by deuterium oxide (D2O), a control length stalk is eventually produced. In D2O-treated cells microtubules are present and in their normal orientation. The inhibition of secretion when microtubules are absent (maytansine) or misdirected (IPC) and the retardation of secretion when microtubule turnover is reduced (D2O) supports a mechanism of granule transport based on the directional turnover of microtubule subunits.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 73-82 
    ISSN: 0886-1544
    Keywords: desmids ; videomicrography ; photokinesis ; photophobic response ; photophosphorylation ; photosynthesis ; phototaxis ; uncouplers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of the uncouplers CCCP and DNP on photokinesis, phototaxis, and the photophobic response in the desmid Cosmarium have been studied both in population systems and by videomicrographic, single-cell analysis. Light-dependent motility is specifically inhibited by both uncouplers, indicating that photokinesis is driven by photophosphorylation. In population experiments, phototaxis and accumulations in light traps due to photophobic responses are inhibited by drug concentrations comparable to those that inhibit photokinesis. Analysis of single-cell behavior demonstrated, however, that neither photophobic responses elicited by an increase in light intensity (step-up response) nor by a decrease (stepdown response) are inhibited, as long as the reduced motility allows the organisms to cross a light--dark border. Phototactic orientation is not impaired by DNP in the single cell analysis, but CCCP significantly reduced the degree of orientation. The results indicate that, although chlorophyll is the photoreceptor for all three photoresponses, at least the photophobic response is independent of both the photosynthetic electron transport chain and photophosphorylation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 91-92 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 0886-1544
    Keywords: cytoplasmic streaming ; motive force ; mitotic cycle ; Physarum polycephalum ; migration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between mitosis and cytoplasmic streaming in the plasmodium of Physarum polycephalum was investigated by simultaneously conducting the following three experiments: (1) identification of the mitotic stages under phase contrast optics, (2) measurement of the rate of oriented migration of the plasmodium on an agar ribbon, and (3) measurement of the motive force of cytoplasmic streaming by the double-chamber method of Kamiya.The migration of the plasmodium almost stopped during synchronous mitosis and the motive force of the flow decreased to 1/4 of the normal level in this period. Gelation of the endoplasm did not occur during the mitotic period, and thus the cessation of the plasmodial migration must have been caused by the diminution of the motive force responsible for cytoplasmic streaming.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 0886-1544
    Keywords: crane flies ; meiosis ; spermatocytes ; chromosome movement ; nuclear envelope ; prophase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Meiotic prophase in spermatocytes of the crane fly, Nephrotoma suturalis, involves both the condensation and the movement of bivalent chromosomes. Since crane flies have only four bivalents that appear highly condensed during late prophase, changes of position and orientation of those bivalents relative to one another can be seen easily in living cells. Chromosome movement during the final 1 to 2 hr of diakinesis was analyzed in detail. Maximal velocities of prophase movements were between 0.1 and 1 μM/min. Metakinetic movements during prometaphase have similar velocities. To assess the physiological basis of prophase movements, experiments employing cyanide and cold treatment were performed. Prophase movements were abolished completely by cyanide, and, for the most part, the velocities of chromosomes in the cold at 2°C and 6°C were less than that of untreated cells at 22°C. The results suggest that prophase movements are energy dependent and may involve an enzyme-catalyzed process occurring in close association with the nuclear envelope.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    ISSN: 0886-1544
    Keywords: intermediate filament ; desmosomes ; epidermal keratinocytes ; nuclear envelope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have shown, by indirect immunofluorescence microscopy using an antiserum against the mouse keratin subunit K2 and by electron microscopy, that transformed (PAM) and primary (PME) mouse epidermal cells possess extensive net works of IF bundles. Following trypsinization and replating of PAM cells, IF bundles are seen to move as a continuous net work from a perinuclear zone into the peripheral cytoplasmic regions. In PAM cells lysed in high-ionic-strength solutions containing Triton ×-100 and DNAase-1, IF bundles appear to be closely associated with nuclear envelope remnants and, in some cases, appear to be attached to nuclear pore complexes. PME cells cultivated in low Ca2+-containing medium possess perinuclear birefringent arrays of IF bundles. Within 2 hours of switching the cells to normal Ca2+ levels, the PME IF bundle network moves towards and establishes contact with the cell surface as desmosomes form. Live cells observed by phase contrast and fixed cells observed by immunofluorescence microscopy demonstrate that desmosomes can be distinguished as dark bands separating neighboring cells. There is little difference between the major proteins seen in SDS-polyacrylamide gel profiles of isolated IF bundle net works from PME cells before and after the Ca2+ switch. Therefore, a reorganization of relatively insoluble membrane-associated protein following the Ca2+ switch may be involved in desmosome formation. The isolated IF networks from PAM cells differ in protein composition compared to the PME IF networks. This may be related to the greatly reduced number of desmosomes in PAM cells. The IF bundle system in epidermal cells appears to be involved in shape formation, shape maintenance, the establishment of desmosomes, nuclear centration, and cell-cell contact.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 0886-1544
    Keywords: directional macrophage motility ; electric fields ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extracellularly applied electric fields (〈 12 V/cm) strongly influence murine resident peritoneal macrophages (Mø) to undergo directional protrusive pseudopodial activity to wards the positive pole of the electric fields in the absence of exogenously applied chemotactic ligands. Internal and external morphological features were not grossly disrupted by the fields. Directional motility induced by the electric fields was inhibited in the presence of 1.0 mM La3+ or 2.5 mM Mg2+ and 5.0 mM EGTA. Effects of the fields were latent in the inhibited cells and directional motility was expressed after termination of the field and removal of the inhibitors. Receptors for the lectins concanavalin A (Con A) and phytohemagglutinin (PHA-L) were uniformly distributed on the surfaces of Mø with no exposure to electric fields. After exposure to the fields, Con A receptors were preferentially distributed on regions of the Mø surface facing the negative pole and PHA-L receptors were preferentially distributed on those regions facing the positive pole. The possibility that directional Mø motility is regulated by the molecular topography of the cell surface is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 0886-1544
    Keywords: spermatozoa ; calcium ion transport ; motility regulation ; cholinergic agonists ; ouabain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Behavioral responses of mature spermatozoa treated with neurotropic factors suggest that calcium entry and intracellular transport may be regulated by a cholinergic mediated program. To test the validity of this proposed mechanism, the effect of several agents on Ca distribution in the sperm cell was examined cytochemically.Sites of Ca accumulation were visualized in thin sections of bull spermatozoa by the application of a modification of Gomori's histochemical procedure for phosphatases. Intact bull sperm cells incubated at room temperature in a buffered balanced salt solution containing 5 mM/liter of CaCl2 showed small, randomly scattered deposits of the reaction product. Similarly treated sperm cells, plasmolyzed in hypoosmotic KCl, revealed a greatly increased amount of deposit associated with the cell membranes (mitochondrial surfaces and plasmalemma), the axonemal complex components, and satellite fibers adjacent to the outer dense fibers. Preincubation of intact cells in nicotine or eserine considerably enhanced the entry of calcium into the cell and its association with the membranes and other intracellular organelles. Decamethonium, an irreversible depolarizer and blocker of cholinergic receptors, interfered with the uptake and intracellular distribution of the calcium. Ouabain, the digitalis glycoside that decreases progressive motility of bull sperm and inhibits Na-, K-ATPase, appears to block Ca efflux, causing an intense accumulation of electron-opaque particles in the plasma membrane while smaller numbers of particles are distributed sparsely throughout the cell interior.The cytochemical results showing enhanced calcium entry in the presence of cholinergic agents, depressed intracellular calcium in cells treated with cholinergic receptor blocker, and intense accumulation of calcium within the cell membrane in the presence of ouabain are consistent with spermatozoan behavioral responses to these agents. These observations support the concept that neurotropic factors may be involved in regulating transmembrane and intracellular transport of ions in control of sperm cell function.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    ISSN: 0886-1544
    Keywords: Mytilus edulis ; 5-hydroxytryptamine ; cilia ; ethanol ; axoneme ; calcium ; filter feeding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The lateral (L) cilia on an isolated filament from the gill of Mytilus edulis remain arrested at the end of their recovery stroke (hands up) when perfused with artificial sea water (ASW). The laterofrontal (LF) cilia continue to be active. The addition of 10% ethanol (ETOH) to the ASW perfusate arrests the LF cilia in a hands-up posture; the L cilia remain undisturbed. By contrast, 10-6 M 5-hydroxytryptamine (5HT) in ASW activates the L cilia and arrests the LF cilia at the end of their effective stroke (hands down). Continued perfusion with 10% ETOH (v/v) in ASW/5HT restores activity to the LF cilia but arrests the L cilia (hands up). These effects are reversible and independent of external Ca2+.Following the detergent extraction of the filament, all gill cilia are inactive. The addition of 0.2 mM ATP in the presence of low Ca2+ (〈 10-7 M) reactivates all model cilia. Under these conditions, 5HT can no longer inhibit the activity of LF cilia and is not required for the activation of the L cilia. This suggests that 5HT acts at a membrane level. An increase in free Ca2+ (〉 10-6 M) arrests the L cilia hands up; the LF cilia remain active. Further Ca2+ increase (〉 10-3 M) induces hands-up arrest of the LF cilia, confirming that the Ca2+ threshold of the two ciliary types is different by several orders of magnitude.The addition of 10% ETOH in low Ca2+ to demembranated reactivated cilia arrests the L cilia hands up while the LF cilia continue to beat. Ten percent ETOH appears to interact with the axoneme, mimicking the effect of high Ca2+ and with the membrane to increase Ca2+ permeability and possibly to inactivate 5HT receptors. These results are discussed in terms of axonemal switching mechanisms and the physiological control of filter feeding in the lamellibranch gill.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 0886-1544
    Keywords: actin gelation ; F-actin nucleation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new actin binding protein has been purified to homogeneity from amoebae of Dictyostelium discoideum. This protein is a single polypeptide with a molecular weight of 120,000 upon sodium dodecyl sulfate gel electrophoresis. It is soluble and trypsin-sensitive, contains no carbohydrate, increases the viscosity and sedimentation rate of F actin, and inhibits the actin-stimulated Mg ATPase of rabbit muscle heavy meromyosin. The interaction of 120,000-dalton protein with F actin is not inhibited by millimolar ATP, pyrophosphate, or micromolar calcium. The 120,000-dalton actin binding protein increases the initial rate of actin polymerization and decreases the critical concentration of actin at steady state.These properties demonstrate that 120,000-dalton protein from Dictyostelium discoidum is not a myosinlike protein. Rather, this protein is probably involved in regulating the assembly of the actin cytoskeletion.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    ISSN: 0886-1544
    Keywords: cellular slime mold ; microtubule-organizing centers ; tubulin ; microtubules ; polymerization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Nucleus associated bodies (NABs) were isolated from Dictyostelium discoideum or Dictyostelium mucoroides and their ability to nucleate microtubules in vitro was examined.NABs were localized at the tapered ends of the nuclei and released from lysed cells in complex with the nuclei. Microtubules radiating from the NAB could also be isolated with the complex under microtubule stabilizing conditions. The ultrastructure of the isolated NAB showed it to be composed of a core structure surrounded by an amorphous matrix.The ability of isolated NABs to nucleate microtubules in vitro was demonstrated by incubation with exogenous brain microtubule protein. Microtubule assembly was easily visualized by dark-field or immunofluorescence microscopy. Polymerization of microtubules seemed to be initiated not from the core structure but from the surrounding matrix.The number of microtubules polymerized from the NAB was directly counted in whole-mount preparations by electron microscopy, which provided a quantitative assay for the NAB activity. The nucleating activity of NAB was quite unstable and its half-life was calculated as about 5 hours. The activity was sensitive to protease digestion and was also temperature sensitive but could be stabilized by addition of glycerol or storage at - 80°C or in liquid nitrogen. These characteristics are analogous to those of the centrosomes in cultured mammalian cells and a possible explanation of their similarity is discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 309-315 
    ISSN: 0886-1544
    Keywords: tropomyosin ; avian muscular dystrophy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The isotype pattern of tropomyosin was investigated in normal and dystrophic avian pectroal muscle using two-dimensional gel electrophoresis. Previous reports have shown that adult pectoral muscle of chickens contains only the α-subunit of tropomyosin and a breast-type troponin-T (TN-T), whereas pectoral fetal muscle contains both α- and β-tropomyosin and leg-type TN-T. The change from the fetal to the adult forms begins shortly after hatching. It has been previously reported that avian dystrophic pectoral muscle contains both the leg- and breast-type TN-T; we show that in avian dystrophic muscle there is also persistent expression of the β-subunit of tropomyosin.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 0886-1544
    Keywords: actin-binding protein ; Dictyostelium ; cytoskeleton ; amoeboid movement ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protein from Dictyostelium discoideum with an apparent subunit molecular weight of 95,000 daltons (95K protein) was previously identified as an actin-binding protein ‘Hellewell and Taylor, 1979’. In this paper, we present a method for purifying the protein, and characterize some important aspects of its structure and function. Purification of the 95K protein is achieved by fractionation with ammonium sulfate followed by chromatography on DEAE-cellulose, gel filtration on 6% agarose, and final purification on hydroxyapatite. The 95K protein is a dimer, composed of apparently identical subunits. It is a rod-shaped molecule, 38 nm in length, with a Stokes radius of 74 Å. In these structural properties, the 95K protein is similar to muscle and nonmuscle α-actinins. The 95K protein and filamin are equally competent, when compared on a weight basis, to enhance the apparent viscosity of actin as determined by falling ball viscometry. The apparent viscosity of mixtures of the 95K protein and actin is dramatically reduced at pH greater than 7.0 or free ‘Ca2+’ greater than 10-7 M. We also examine the mechanism by which calcium regulates the interaction of the 95K protein and actin. A change in free ‘Ca2+’ induces no detectable change in the quaternary structure of the 95K protein. Our experiments indicate that the 95K protein does not dramatically alter the length distribution of actin filaments in the presence of micromolar free ‘Ca2+’. A large fraction of the 95K protein cosediments with actin in the presence of low free ‘Ca2+’ (ca. 3 × 10-8M), but not in the presence of high free ‘Ca2+’ (ca. 4 × 10-6M). We conclude that increased free ‘Ca2+’ inhibits gelation of actin by the 95K protein by reducing the affinity of the 95K protein for actin. We propose that 95K protein is an important component of the cytoskeletal/contractile system in D. discoideum amoebae.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 35-39 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 41-45 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 53-57 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 47-51 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 77-81 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 137-141 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 143-147 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 149-152 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 153-158 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 165-168 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 169-173 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability