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  • 1
    Electronic Resource
    Electronic Resource
    Cross-bridge behavior in rigor muscle (1980)
    Springer
    European biophysics journal 7 (1980), S. 51-63 
    Details
    ISSN: 1432-1017
    Keywords: Muscle rigor ; Cross-bridge model ; Insect fibrillar muscle ; Cross-bridge stiffness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Properties of the rigor state in muscle can be explained by a simple cross-bridge model, of the type which has been suggested for active muscle, in which detachment of cross-bridges by ATP is excluded. Two attached cross-bridge states, with distinct force vs. distortion relationships, are required, in addition to a detached state, but the attached cross-bridge states in rigor muscle appear to differ significantly from the attached cross-bridge states in active muscle. The stability of the rigor force maintained in muscle under isometric conditions does not require exceptional stability of the attached cross-bridges, if the positions in which attachment of cross-bridges is allowed are limited so that the attachment of cross-bridges in positions which have minimum free energy is excluded. This explanation of the stability of the rigor state may also be applicable to the maintenance of stable rigor waves on flagella.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538158
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  • 2
    Electronic Resource
    Electronic Resource
    ‘Electro-Chemical’ Orientation of Bracken Spermatozoids (1957)
    [s.l.] : Nature Publishing Group
    Nature 179 (1957), S. 525-525 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig 1. Aggregation of spermatozoids at the tip of a capillary containing sodium L-malate. (x 34) Fig 2. Aggregation of spermatozoids at border between buffered region (darkened by-indicator) and acidified region. (x 22) Fig 3 Spermatozoids swimming to anode (at top) in electric field, in presence ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/179525a0
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  • 3
    Electronic Resource
    Electronic Resource
    Bend Propagation along Flagella (1966)
    [s.l.] : Nature Publishing Group
    Nature 209 (1966), S. 161-163 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE planar undulatory waves which are the most familiar type of flagellar movement are composed of curved regions forming circular arcs, separated by shorter unbent regions1,2. These waves can be generated by the propagation along the flagellum of rather abrupt transitions between straight and bent ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/209161a0
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of AMPPNP and vanadate on the mechanochemical crossbridge cycle in flagella (1981)
    Springer
    Journal of muscle research and cell motility 2 (1981), S. 131-140 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The non-hydrolysable ATP analogue, β,γ-imido-adenosine-5′-triphosphate (AMPPNP, adenylylimidodiphosphate) does not reduce the stiffness of demembranated sea urchin sperm flagella measured in the rigor state in the absence of MgATP2− and does not cause relaxation of rigor bends. The competitive inhibition of flagellar beat frequency by AMPPNP is not enhanced by vanadate. These observations provide further evidence that the dynein-tubulin crossbridge cycle in flagella is similar to the actin-myosin crossbridge cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712064
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  • 5
    Electronic Resource
    Electronic Resource
    Resolution of the competitive inhibitory effects of lithium and AMPPNP on the beat frequency of ATP-reactivated, demembranated, sea urchin sperm flagella (1985)
    Springer
    Journal of muscle research and cell motility 6 (1985), S. 507-512 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary About half of the inhibitory effect on the beat frequency of sea urchin spermatozoa flagella by β, γ-imido-adenosine-5′-triphosphate (AMPPNP) previously reported by Okuno & Brokaw (1981) was actually the result of inhibition by lithium resulting from the use of a tetralithium salt of AMPPNP. Li+ (or LiATP3−) acts as a competitive inhibitor of beat frequency, with aK i for Li+ of about 30 mM. Under improved reactivation conditions which reduce theK m for beat frequency to about 0.1 mM, theK i for lithium-free MgAMPPNP2− is about 2.3 mM, and magnesium pyrophosphate (MgPP i − ), which may be an equivalent ligand, gives aK i of 3.4 mM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712586
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  • 6
    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
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  • 7
    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
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  • 8
    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
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  • 9
    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
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  • 10
    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
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