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  • Life and Medical Sciences  (10)
  • symmetry  (2)
  • 1
    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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  • 2
    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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  • 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
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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Calcium and flagellar response during the chemotaxis of bracken spermatozoids (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 83 (1974), S. 151-158 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The attraction of fern spermatozoids by secretions from the female reproductive structures, and by salts of malic acid, has long been known as a classic example of precise chemotactic orientation by motile cells. Spermatozoids of the bracken fern are attracted by the partially ionized form of malic acid, bimalate ion, and also by calcium ions. Both calcium and bimalate ions must be present for chemotactic response and for response to voltage gradients, Spermatozoids swimming up a bimalate concentration gradient swim in helical paths of abnormally small radius; if they accidentally swim down the concentration gradient the radii of their path helices become abnormally large.These observations suggest that changes in the direction of flagellar beating in response to the rate of change of bimalate ion concentration with time may be the basis for chemotactic orientation. A “coupled diffusion” hypothesis for chemo-reception is presented, which postulates a membrane carrier which can only circulate freely in the membrane if it binds both bimalate and calcium ions. This hypothesis could explain time-differentiation of the stimulus, the coupling of a specific stimulus  -  bimalate ions  -  to a general mediator of intracellular response  -  calcium ions  -  and the quantitative relationship between response of the spermatozoids and the chemical potential of “calcium bimalate.”
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040830118
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  • 9
    Electronic Resource
    Electronic Resource
    Random and oriented movements of bracken spermatozoids (1959)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 54 (1959), S. 95-101 
    Details
    ISSN: 0095-9898
    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
    URL: http://dx.doi.org/10.1002/jcp.1030540110
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  • 10
    Electronic Resource
    Electronic Resource
    cAMP-dependent phosphorylation associated with activation of motility of Ciona sperm flagella (1983)
    New York, NY : Wiley-Blackwell
    Gamete Research 8 (1983), S. 201-218 
    Details
    ISSN: 0148-7280
    Keywords: protein kinase ; cyclic AMP ; phosphorylation ; flagella ; motility ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Demembranated spermatozoa of Ciona do not become motile when provided with MgATP, unless their motility is activated in vivo before demembranation or unless the demembranated spermatozoa are activated in vitro with cAMP or with the catalytic subunit of a cAMP-dependent protein kinase. CAMP causes a greater than fivefold enhancement of 32P incorporation by demembranated spermatozoa. Analysis by one-dimensional PAGE and autoradiography shows several axonemal protein bands that become 32P-labeled during in vitro activation with cAMP and identifies protein bands whose labeling is specifically reduced if motility of the spermatozoa is activated before demembranation, suggesting that these proteins also become phosphorylated during activation of motolity in vivo. These phosphorylated proteins appear to include dynein heavy-chain components, but axonemal tubulin is not phosphorylated. Partially phosphorylated spermatozoa can be activated by an increase in KCI concentration, which appears to dissociate one phosphorylated component from the axoneme.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120080302
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