ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • Articles  (18)
  • flagella  (18)
  • Wiley-Blackwell  (18)
  • Medicine  (18)
  • Political Science
Collection
  • Articles  (18)
Source
Keywords
Publisher
  • Wiley-Blackwell  (18)
Years
Topic
  • Medicine  (18)
  • Political Science
  • Biology  (20)
  • 1
    Electronic Resource
    Electronic Resource
    Bending patterns of chlamydomonas flagella I. Wild-type bending patterns (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 131-150 
    Details
    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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Bending patterns of Chlamydomonas flagella: III. A radial spoke head deficient mutant and a central pair deficient mutant (1985)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 195-208 
    Details
    ISSN: 0886-1544
    Keywords: central pair ; radial spoke ; flagella ; mutant ; Chlamydomonas ; suppressor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flash photomicrography at frequencies up to 300 Hz and computer-assisted image analysis have been used to obtain parameters describing the flagellar bending patterns of mutants of Chlamydomonas reinhardtii. All strains contained the uni1 mutation, to facilitate photography. The radial spoke head deficient mutant pf17, and the central pair deficient mutant, pf15, in combination with suppressor mutations that restore motility without restoring the ultrastructural or biochemical deficiencies, both generate forward mode bending patterns with increased shear amplitude and decreased asymmetry relative to the “wild-type” uni1 flagella described previously. In the reverse beating mode, the suppressed pf17 mutants generate reverse bending patterns with large shear amplitudes. Reverse beating of the suppressed pf15 mutants is rare. There is a reciprocal relationship between increased shear amplitude and decreased beat frequency, so that the velocity of sliding between flagellar microtubules is not increased by an increase in shear amplitude. The suppressor mutations alone cause decreased frequency and sliding velocity in both forward and reverse mode beating, with little change in shear amplitude or symmetry.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970050303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Calcium-induced change in form of demembranated sea urchin sperm flagella immobilized by vanadate (1981)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1981), S. 349-362 
    Details
    ISSN: 0886-1544
    Keywords: Ca2+ ; flagella ; symmetry ; vanadate ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increased Ca2+ concentration causes a reversible increase in asymmetry of the flagellar bending waves of “potentially symmetric” demembranated sea urchin spermatozoa. When these flagella are immobilized with 5 μM vanadate, increased Ca2+ concentration causes a reversible increase in the total bend angle between the tip and the base of the immobilized flagella. These effects of Ca2+, and the movement which can be activated by CaATP2-, can be inhibited by vanadate, but in both cases, high concentrations of vanadate, of the order of 100 μM, are required. These observations suggest that ATP, possibly in the form of CaATP2-, is required for the Ca2+-induced change in shape of the flagella, but other observations suggest that the magnitudes of asymmetry and total bend angle are more closely related to Ca2+ concentration than to CaATP2- concentration.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of Triton-extraction conditions on beat symmetry of sea urchin sperm flagella (1981)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1981), S. 363-370 
    Details
    ISSN: 0886-1544
    Keywords: Ca2+ ; Mg2+ ; symmetry ; flagella ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Potentially asymmetric spermatozoa are obtained when spermatozoa are demembranated in the presence of a low Ca2+/Mg2+ ion concentration ratio. They swim with asymmetric bending waves even when reactivated at low Ca2+ concentrations, and become more asymmetric when Ca2+ is increased. Potentially symmetric spermatozoa, which swim with symmetric bending waves at low Ca2+ and become asymmetric as the Ca2+ is increased, can be obtained by exposing the flagella to a high Ca2+/Mg2+ ratio, either during or subsequent to demembranation. The rate of this conversion is an increasing function of temperature and Triton concentration. Potentially symmetric spermatozoa can be reconverted to potential asymmetry, if the exposure to high Ca2+/Mg2+ is brief, and is terminated by addition of EGTA and Mg2+ before diluting the spermatozoa. The conversion to potential symmetry may involve removal of a labile component from the axoneme.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010307
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Automated methods for estimation of sperm flagellar bending parameters (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 417-430 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; image analysis ; microcomputer ; motility ; parameter estimation ; Simplex method ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Parameters to describe flagellar bending patterns can be obtained by a microcomputer procedure that uses a set of parameters to synthesize model bending patterns, compares the model bending patterns with digitized and filtered data from flagellar photographs, and uses the Simplex method to vary the parameters until a solution with minimum root mean square differences between the model and the data is found. Parameters for Chlamydomonas bending patterns have been obtained from comparison of shear angle curves for the model and the data. To avoid the determination of the orientation of the basal end of the flagellum, which is required for calculation of shear angles, parameters for sperm flagella have been obtained by comparison of curves of curvature as a function of length for the model and for the data. A constant curvature model, modified from that originally used for Chlamydomonas flagella, has been used for obtaining parameters from sperm flagella, but the methods can be applied using other models for synthesizing the model bending patterns.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040603
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Bending patterns of Chlamydomonas flagella: II. Calcium effects on reactivated Chlamydomonas flagella (1985)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 53-60 
    Details
    ISSN: 0886-1544
    Keywords: calcium ; Chlamydomonas ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ca2+ has profound effects on the movement of cilia and eukaryotic flagella, including those of Chlamydomonas. Two clear changes seen in Chlamydomonas flagella with changes in Ca2+ are beat frequency and symmetry. Photographic and computer assisted analysis of flagellar bending patterns on a uniflagellate mutant of Chlamydomonas have been used to examine details of the effects of Ca2+ on the movement of ATP-reactivated, demembranated flagella. In addition to the forward mode bending pattern seen at low Ca2+ concentrations (10-9 M), which has a frequency of about 50 Hz and the reverse mode bending pattern seen at high Ca2+ concentrations (10-4 M) with a frequency around 70 Hz, we carefully examined bending patterns in the intermediate Ca2+ concentration range of 1-6.5 × 10-6 M. In this intermediate range, the bending patterns have significantly reduced asymmetry and slightly increased frequency, compared to the motility observed at low Ca2+ concentrations. These observations indicate that changes in these two parameters of motion do not occur in parallel and suggest that the effects of Ca2+ may be a multicomponent process. Physiologically, these changes in the beat pattern at intermediate Ca2+ may signal either (1) the beginning stages of transition to the symmetrical, high-frequency beating seen at high Ca2+, or (2) a more normal forward mode motility for the trans flagellum as suggested by Kamiya and Witman [1984]. No large amplitude bending patterns associated with transitions between forward and reverse mode beating in intact cells were seen at the intermediate Ca2+ concentrations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970050105
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Evolution of the flagellar waveform of ram spermatozoa in relation to the degree of epididymal maturation (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 8-18 
    Details
    ISSN: 0886-1544
    Keywords: spermatozoa ; flagella ; motility ; epididymis ; maturation ; mammal ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility and flagellar movement of ram spermatozoa along the epididymis were analysed in vitro. From the caput to the cauda of the epididymis, the percentage of motile and progressive spermatozoa increases. No flagellar bending was observed in spermatozoa from the testis or the epididymal anterior caput. When spermatozoa reached the distal caput of the epididymis, a static curvature, associated with an initiation of the flagellar beating, appeared on the flagella. This curvature normally disappeared during epididymal transit. Its disappearance was associated with an increase in the flagellar beat efficiency. Our results suggest that the initiation of motility is related to two mechanisms involving: (1) the presence of a transient static curvature, and (2) the establishment of a symmetric regular beating of the flagellum. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230103
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Control of flagellar bending: A new agenda based on dynein diversity (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 28 (1994), S. 199-204 
    Details
    ISSN: 0886-1544
    Keywords: axoneme ; cilia ; flagella ; microtubule ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations that were interpreted to provide evidence for equivalent functions of all axonemal dyneins should be reinterpreted, and models based on this assumption should be abandoned. In the future, attempts to understand the mechanisms for flagellar bending, oscillation, and bend propagation should start from the assumption that each type of axonemal dynein may have a specific function. At least three distinct functions can now be identified: bend initiation, maintenance of the angle of propagating bends, and generation of power to overcome viscous resistances. Only the last of these three functions is an outer arm dynein function. © 1994 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970280303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Computer simulation of bend propagation by axoplasmic microtubules (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 347-353 
    Details
    ISSN: 0886-1544
    Keywords: axoplasmic transport ; flagella ; microtubule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The generation of bending waves by microtubules in squid nerve axoplasm has been modelled using appropriately modified versions of computer programs developed previously for simulation of flagellar bending waves. The results confirm that a constant longitudinal force directed along the axis of the microtubule is sufficient to cause the generation of regular oscillations and propagated bending waves when the forward gliding movement of the microtubule is obstructed. No control mechanism is required to modulate the active force-generating system. In order to obtain bending waves similar to those observed experimentally, it was necessary to use a model for the force-generating system in which the active force decreases with increasing sliding velocity. If the elastic bending resistance of axoplasmic microtubules is similar to that of microtubules in sperm terminal filaments, the longitudinal force per unit length generated by the axoplasmic microtubules must be of the same order of magnitude as the force generated by dynein arms along the doublet microtubules of eukaryotic flagella.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060311
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Bending patterns of Chlamydomonas flagella: IV. Mutants with defects in inner and outer dynein arms indicate differences in dynein arm function (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 68-75 
    Details
    ISSN: 0886-1544
    Keywords: dynein ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mutants with outer dynein arm defects or deficiencies all show a major reduction in beat frequency to about half the normal value; some of these mutants show an additional decrease in sliding velocity associated with reduced shear amplitude and an additional reduction in beat frequency, as well as other more minor modifications of the normal forward mode bending pattern. New mutants (ida98, pf30), which appear to be deficient in a subset of inner dynein arms show a reduction in sliding velocity that is primarily associated with a reduction in shear amplitude, with only a small reduction in beat frequency. These differences in motility phenotype between inner and outer dynein arm mutants suggest that inner and outer dynein arms may have distinct functions. The relatively large decrease in sliding velocity associated with partial loss of inner arms is consistent with earlier observations on pf23, a nonmotile mutant lacking inner arms, suggesting that inner arms may have an essential function in motility. The ability to generate reverse mode bending patterns is retained in some inner or outer dynein arm mutants, but appears to be decreased in those mutants which show reduced shear amplitude for the forward mode bending pattern.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080110
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...