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  • Life Sciences (General)  (103)
  • Cell & Developmental Biology  (81)
  • 1
    Electronic Resource
    Electronic Resource
    The cytoskeletal system of mammalian primitive erythrocytes: Studies in developing marsupials (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 133-145 
    Details
    ISSN: 0886-1544
    Keywords: marsupials ; mammals ; primitive erythrocytes ; nucleated erythrocytes ; marginal bands ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Seeking to resolve conflicting literature on cytoskeletal structure in mammalian “primitive” generation erythrocytes, we have utilized the circulating blood of developing marsupials. In young of the Tammar Wallaby (Macropus eugenii) and the Gray Short-tailed Opossum (Monodelphis domestica), relatively large, nucleated primitive erythrocytes constituted nearly 100% of the circulating population of birth (= day 0) and in fetuses (Tammar) several days before birth. These cells were discoidal or elliptical, and flattened except for a nuclear bulge. Their cytoskeletal system, consisting of a marginal band of microtubules enclosed within a cell surface-associated network (membrane skeleton), closely resembled that of non-mammalian vertebrate erythocytes. By day 2 or 3, much smaller anucleate erythrocytes of “definitive” morphology, lacking marginal bands, appeared in abundance. These accounted for 〉90% of the circulating population of both species by day 6-8. Non-nucleated erythrocytes of a different type, constituting 1-6% of the cells in most blood samples up to day 7, were identified as anucleate primitives on the basis of size, shape, and presence of a marginal band. Thus, loss of erythrocyte nuclei in mammals appears to begin earlier than generally recognized, i.e., in the primitive generation. Counts of these anucleate primitives in young of various ages implicated nucleated primitives as their probable source. Pointed erythrocytes, occasionally found in younger neonates of both species, occurred in greatest number in fetuses (Tammar) prior to birth. This is in accord with previous work on non-mammalian vertebrates suggesting that such cells are morphogenetic intermediates. The results confirm the long-suspected similarity between mammalian primitive erythrocytes and the nucleated erythrocytes of all non-mammalian vertebrates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160207
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on the role of protein kinases in the TNF-mediated enhancement of murine tumor cell-endothelial cell interactions (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 47 (1991), S. 62-78 
    Details
    ISSN: 0730-2312
    Keywords: tumor necrosis factor-α ; tumor cell adherence ; PKC ; PKA ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have previously demonstrated that the exposure of mouse microvascular endothelium (MME) to tumor necrosis factor-α (TNF) led to the increased binding of mouse mastocytoma cells (P815) to endothelial monolayers (Bereta et al., in press). In the current study we examined the possible involvement of protein kinases in TNF signal transduction in the endothelial cells. PKA does not appear to play a role in the potentiation of binding by TNF. We found that the TNF-generated signal is inhibited by H-7 and sangivamycin, but not by staurosporine. TNF did not cause translocation of PKC to the cell membrane and its effect could not be completely mimicked by PMA nor by PMA in the presence of calcium-raising agents. Thus, we concluded that the “classical” PKC pathway is not completely responsible for TNF signalling in this system. We also found that staurosporine itself strongly enhanced adhesion of tumor cells to endothelium, utilizing a mechanism distinct from that of TNF. Although the data provide evidence for the role of kinases in the effect of TNF on binding of tumor cells to MME, this role appears to be a complex one.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240470109
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  • 3
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    Experiment K-7-30: Effects of Spaceflight in the Cosmos Biosatellite 2044 on the Vestibular-Ocular Reflex (VOR) of Rhesus Monkeys (1994)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This technical paper discusses the following: (1) The VOR of two rhesus monkeys was studied before and after 14 days of spaceflight to determine effects of microgravity on the VOR. Horizontal, vertical and roll eye movements were recorded in these and six other monkeys implanted with scleral search coils. Animals were rotated about a vertical axis to determine the gain of the horizontal, vertical and roll VOR. They were rotated about axes tilted from the vertical (off-vertical axis rotation, OVAR) to determine steady state gains and effects of gravity on modulations in eye position and eye velocity. They were also tested for tilt dumping of post-rotatory nystagmus. (2) The gain of the horizontal VOR was close to unity when animals were tested 15 and 18 hours after flight. VOR gain values were similar to those registered before flight. If the gain of the horizontal VOR changes in microgravity, it must revert to normal soon after landing. (3) Steady state velocities of nystagmus induced by off-vertical axis rotation (OVAR) were unchanged by adaptation to microgravity, and the phase of the modulations was similar before and after flight. However, modulations in horizontal eye velocity had more variation after landing and were on mean about 50% larger for angles of tilt of the axis of rotation between 50 and 90?/s after flight. This difference was similar in both animals and was significant. (4) A striking finding was that tilt dumping was lost in the one animal tested for this function. This loss persisted for several days after return. This is reminiscent of the loss of response to pitch while rotating in the M-131 experiments of Skylab, and must be studied in detail in future spaceflights. (5) Thus, two major findings emerged from these studies: after spaceflight the modulation of horizontal eye velocity was larger during OVAR, and one animal lost its ability to tilt-dump its nystagmus. Both findings are consistent with the postulate that adaptation to microgravity causes alterations in the way that otolith information is processed in the central nervous system. The experiments lay the groundwork for studying the vertical and roll VOR before and after future space flights, as well as for studying modulations in vertical and roll eye position during OVAR and tilt dumping.
    Keywords: Life Sciences (General)
    Type: US Experiments Flown on the Soviet Biosatellite Cosmos 2044; 285-302; NASA-TM-108802
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    NASA TECHNICAL REPORTS
  • 4
    Electronic Resource
    Electronic Resource
    Plants contain highly divergent actin isovariants (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 276-290 
    Details
    ISSN: 0886-1544
    Keywords: isoforms ; cytoskeleton ; angiosperms ; synthetic peptides ; IEF-SDS PAGE ; Western blot ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin protein isovariants have been identified in animals with distinct cytoplasmic or muscle specific patterns of expression. Analysis of vascular plant actin gene sequences suggests that an even greater diversity should exist within the plant actin protein families, but previous studies on plant proteins have not demonstrated the presence of multiple actin isovariants. Antibodies recognizing a conserved amino-terminal plant actin peptide, a family of plant actin peptides from a variable region, and two monoclonal antibodies to conserved epitopes within animal actins were used to identify isovariants of soybean actin resolved by two-dimensional isoelectric focusing (IEF) sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Approximately six to eight actin isovariants with pi values ranging from 5.1 to 5.8 have been identified from soybean hypocotyls. Stems, leaves, and roots with varying amounts of most isovariants present in all four organs. Acidic isovariants were present in much higher levels in leaves and stems. Antisera with λ-class actin specificity detected a subset of three isovariants in all organs examined. One monoclonal and one antipeptide antisera are shown to react well with a wide variety of plant actin isovariants. Similar patterns of actin isovariants were detected in the distant angiosperms, Arabidopsis petunia, and maize. It is likely that many of these diverse classes of isovariants have been preserved throughout vascular plant evolution and reflect the ancient diversity within plant actin gene families. The extreme difference among isovariants implies the presence of a complex actin-based cytoskeletal system in plants.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170403
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  • 5
    Electronic Resource
    Electronic Resource
    Assembly and bundling of marginal band microtubule protein: Role of tau (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 57-71 
    Details
    ISSN: 0886-1544
    Keywords: microtubule bundling ; cytoskeleton ; tau ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubule protein extracted from dogfish erythrocyte cytoskeletons by disassembly of marginal bands at low temperature formed linear microtubule (MT) bundles upon reassembly at 22°C. The bundles, which were readily visible by video-enhanced phase contrast or DIC microscopy, increased in length and thickness with time. At steady state after 1 hour, most bundles were 6-11 μm in length and 2-5 MTs in thickness. No inter-MT cross-bridges were visible by negative staining. The bundles exhibited mechanical stability in flow as well as flexibility, in this respect resembling native marginal bands. As analyzed by SDS-PAGE and immunoblotting, our standard extraction conditions yielded MT protein preparations and bundles containing tau protein but not high molecular weight MAPs such as MAP-2 or syncolin. In addition, late fractions of MT protein obtained by gel filtration were devoid of high molecular weight proteins but still produced MT bundles. The marginal band tau was salt-extractable and heat-stable, bound antibodies to mammalian brain tau, and formed aggregates upon desalting. Antibodies to tau blocked MT assembly, but both assembly and bundling occurred in the presence of antibodies to actin or syncolin. The MTs were “unbundled” by subtilisin or by high salt (0.5-1 M KCl or NaCl), consistent with tau involvement in bundling. High salt extracts retained bundling activity, and salt-induced unbundling was reversible with desalting. However, reversibility was observed only after salt-induced MT disassembly had occurred. Reconstitution experiments showed that addition of marginal band tau to preassembled MTs did not produce bundles, whereas tau presence during MT reassembly did yield bundles. Thus, in this system, tau appears to play a role in both MT assembly and bundling, serving in the latter function as a coassembly factor. © 1994 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970290106
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  • 6
    Electronic Resource
    Electronic Resource
    Cytochalasin J affects chromosome congression and spindle microtubule organization in PtK1 cells (1995)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 32 (1995), S. 245-257 
    Details
    ISSN: 0886-1544
    Keywords: actin ; cytochalasin ; microfilaments ; microtubules ; mitosis ; mitotic apparatus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: PtK1 cells were treated with 10 μg/ml cytochalasin J (CJ) for 15 min at various stages of mitosis. When applied at nuclear envelope breakdown (NEB) chromosome congression was blocked or substantially slowed, and chromosomes failed to show organization patterns typical of prometaphase. Spindle microtubule (MT) numbers appeared unaffected as judged by the pattern of birefringent retardation. However, ultrastructural analysis showed MTs to be reorganized within the spindle domain with some exhibiting fragmentation and others failing to interact with poorly defined kinetochore laminae. The spindle domain took on a curved, almost banana-like shape, as related to the position of the centrosomes and lack of orientation of chromosomes. Serial section analysis of kinetochore regions showed reduced contour length and maturation of the kinetochore plate with few MTs associated with this structure. Cells similarly treated with 10 μg/ml CJ at NEB for 15 min and then released into conditioned medium for 15 min showed that most chromosomes resumed congression to the metaphase plate. Ultrastructural analysis revelaed a more normal organization of spindle MTs, but kinetochore structure remained affected. CJ treatment of cells in prometaphase slightly affected chromosome congression with most chromosomes aligning at the metaphase plate after 10-15 min of treatment. Ultrastructural analysis showed that astral MTs were disrupted and spindle MTs were fragmented; few MTs coursed from kinetochore to pole. Kinetochore structure was also affected with only small numbers of short MTs seen associated with kinetochores. Application of CJ at anaphase onset had little effect on anaphase A and B, but cytokinesis failed to occur. Anti-tubulin staining of a monolayer of cells treated with 10 μg/ml CJ for 15 min showed that over 60% of mitotic figures exhibited changes in MT organization. Cells showing the greatest effect of treatment had several foci of bundles of MTs, as if the spindle were multipolar. Chromosomes were arranged near the periphery of the spindle which could be a result of abnormalities of kinetochore structure. Improper association of spindle MTs with kinetochores and, thus, changes in kinetochore position could account for these changes in spindle architecture. © 1995 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970320402
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  • 7
    Electronic Resource
    Electronic Resource
    Cellular morphogenesis and the formation of marginal bands in amphibian splenic erythroblasts (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 157-168 
    Details
    ISSN: 0886-1544
    Keywords: axolotl ; cell differentiation ; cell shape ; cytoskeleton ; nucleated erythrocyte ; microtubule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spleen of Ambystoma mexicanum (axolotl) larvae develops as a closed sac containing differentiating nucleated erythrocytes, and is typically isolated from the general circulation for about 10 days post-hatching. Beginning 3-4 days posthatching, it can be removed intact for examination of the morphology and cytoskeletal structure of the erythropoietic cells. In the smallest (earliest) spleens, spheroidal cells predominate, while older ones contain a preponderance of cells exhibiting the flattened elliptical morphology typical of all non-mammalian vertebrate erythrocytes. Most striking in the splenic erythroid population are cells with singly or doubly pointed morphology. Though common in the developing spleen and circulation of young larvae, pointed cells are less frequently encountered in the circulation of older larvae, indicating that they are intermediate stages in the differentiation of spheroids to flattened ellipsoids. This is supported by structural observations on cytoskeletons prepared from the splenic cells. Incomplete singly and doubly pointed marginal bands of microtubules are observed, many of which contain a pair of centrioles within or close to a pointed end, suggestive of organizing center function. The observations are consistent with a sequence of changes in cell morphology from spherical to doubly pointed to singly pointed to flattened ellipse, causally linked to stages of marginal band biogenesis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970120305
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  • 8
    Electronic Resource
    Electronic Resource
    Localization of tau and other proteins of isolated marginal bands (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 350-360 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; MAPs ; cytoskeleton ; tau ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To determine which proteins were associated with and intrinsic to the marginal band (MB) of microtubules (MTs), we studied protein components of MBs isolated from nucleated erythrocytes by differential detergent solubilization of the membrane skeleton (MS). MBs isolated from dogfish erythrocytes contained major proteins in the tubulin Mr range. A high molecular weight protein of ∼290 kD that bound antibody to syncolin and to heat-stable brain MAPs was present in the whole cytoskeleton. However, most of it was solubilized by the MB isolation medium, together with the MS. Dogfish erythrocyte cytoskeletons and isolated MBs were examined with polyclonal and monoclonal antibodies against mammalian brain tau and chicken erythrocyte tau. As shown by immunofluorescence and immunoblotting, these antibodies bound to proteins in the 50 to 67 kD range, located along the length of isolated MBs. Two-dimensional SDS-PAGE revealed isolated MB proteins of pI ∼6.8 in the same molecular weight range, as well as α- and β-tubulin with pI ∼5.4. Subtilisin or high-salt treatment of isolated MBs resulted in unbundling of MTs, indicating involvement of MAPs. MBs isolated from chicken erythrocyte cytoskeletons also contained tau as shown by antimammalian brain tau immunofluorescence. Both chicken and dogfish isolated MBs also bound phalloidin, but the binding was usually discontinuous and, for any given MB, matched the pattern of anti-syncolin binding. Both syncolin and F-actin were part of the MS remnant remaining after MT disassembly, supporting their assignment to a specialized MS region at the MB/MS interface. In contrast, tau protein appears to be intrinsic to the MB, where it may have an MT stabilizing and bundling function. © 1994 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970270407
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  • 9
    Electronic Resource
    Electronic Resource
    Organization and dynamics of a cortical fibrous network of Paramecium: The outer lattice (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 315-324 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; cell morphogenesis ; immunofluorescence ; antimyosin monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A monoclonal antibody, CC212, raised against ciliated cortices of quail oviduct cells and characterized as an antimyosin of smooth muscle and nonmuscle cells, was shown to specifically label a regular cortical network in Paramecium and to recognize two Triton X-100-insoluble polypeptides at 130 and 50 kDa. However, no evidence was obtained that these polypeptides are related to myosin.An immunofluorescence study and ultrastructural immunogold localization allowed us to identify the CC212-decorated material as a component of the outer lattice, a submembrane cytoskeletal network which runs along the top of the ridges visible by scanning electron microscopy and delineates the periphery of each cortical unit. The dynamics of the outer lattice during the cell cycle was studied by immunofluorescence and it was found that the outer lattice growth is achieved without disruption of the preexisting meshes by longitudinal elongation and additon of new transverse partitions. A striking disorganization of the outer lattice was observed in a thermosensitive mutant primarily altered in basal body duplication. These observations suggest possible functions of the outer lattice and demonstrate the interdependence of basal body duplication, surface growth, and outer lattice remodelling.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070404
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  • 10
    Electronic Resource
    Electronic Resource
    Cytochalasins induce actin polymerization in human leukocytes (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 58-64 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; neutrophils ; lymphocytes ; metabolic inhibitors ; F-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We studied the effect of cytochalasins (B, D, and E) on the F-actin content in human neutrophils and lymphocytes using NBD-phallacidin labeling followed by flow cytometry. All three cytochalasins induced a concentration- and time-dependent increase in the F-actin content in both cell types. The order of potency was cytochalasin D 〉 E 〉 B. The increase in F-actin content was accompanied by a decrease in the G-actin content as measured by DNase I inhibition assay. These observations suggest that in intact cells cytochalasins may function differently compared to purified and semipurified systems, and their effects may be modified through other actin-binding or sequestering proteins. 2-deoxyglucose (20 mM) caused a decrease in the basal F-actin content and significantly reduced the change induced by the cytochalasins. These results suggest that the state of actin in intact cells is regulated by cytosolic ATP levels, primarily by the integrity of the glycolytic pathway. Based on these observations, we conclude that the mechanism of action of cytochalasins in intact cells is more complex than current models suggest.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210107
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