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  • 1
    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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  • 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
    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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    Paper (German National Licenses)
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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative analysis of axonemal bends and twists in the quiescent state of ciona sperm flagella (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 247-259 
    Details
    ISSN: 0886-1544
    Keywords: spermatozoa ; Ciona ; axoneme ; quiescence ; twist ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A simple planar model of sliding can predict the amount of sliding required to form a certain degree of bend. The accuracy of this prediction relies on the assumptions that no twists occur in the axoneme and that no sliding occurs at the base. However, previous studies indicated that twists may occur.This paper explores a new method for quantitating and analyzing twists. Preliminary results using this method showed that there were twists. In order to control for possible artifacts due to fixation and other preparative procedures, the characteristic S-shaped quiescent state of Ciona spermatozoa was studied.Analyses of platinum replicas of those flagella in which this waveform is well preserved suggest that most, if not all, of the twists observed are due to the artifact of a curved shape settling onto a surface. Detailed analyses indicate that if twists do occur in quiescent sperm, they are probably less than 0.4 radian. Since axonemes are evidently easily twisted in rigor, and even after fixation, caution should be exercised in interpretation of axonemal twists.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030305
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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    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
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