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  • Ciona spermatozoa  (1)
  • Simplex method  (1)
  • asymmetric beating  (1)
  • 1
    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
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of the average shape of flagellar bends: A gradient curvature model (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 312-324 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; sea urchin spermatozoa ; waveform analysis ; Ciona spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Data obtained by manual digitization of photographs of flagellar bending waves have been analyzed by determining size parameters for the bends by least-squares fitting of a model waveform. These parameters were then used to normalize the data so that the average shape of the bends could be determined. Best fits were obtained with a model waveform derived from the constant curvature waveforms used previously but with provision for a linear change in curvature across the central region of the bend-the gradient curvature model (GCM). The central regions of the GCM bending waves are separated by transition regions with length determined by a parameter called the truncation factor (FT). Fitting the GCM to sine-generated bending waves give optimal fit when FT = 0.34. Fitting the GCM to four different samples of flagellar bending waves gave best fits with values of FT ranging from 0.17 for ATP-reactivated Lytechinus spermatozoa beating at approximately 10 Hz to 0.32 for live spermatozoa of Arbacia. The difference between the Arbacia waveforms and a sine-generated waveform is therefore very small, but a sine-generated waveform lacks the degree of freedom represented by FT that is required to fit other waveforms optimally.The residual differences between the waveform data and optimal GCM waveforms were averaged and found to be small. In most cases, the curvature in the central region of the optimal GCM decreased in magnitude towards the tip of the flagellum; however, this slope was highly variable and sometimes positive. Significant variations in both this slope and FT were found in individual bends as they propagated along a flagellum.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970090404
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    New evidence for a “biased baseline” mechanism for calcium-regulated asymmetry of flagellar bending (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 160-168 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; asymmetric beating ; sea urchin ; Ciona ; Chlamydomonas ; switching mechanism ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Time-averaged data covering six to ten beat cycles for ATP-reactivated spermatozoa of a sea urchin and Ciona, and from a uniflagellate mutant of Chlamydomonas, were analyzed to obtain parameters of oscillation and mean shear angle at each point along the flagellum. The mean shear angles usually show a sharp change near the base of Ihc flagellum. This sharp basal change in angle is correlated with perceived asymmetry in the development times of principal and reverse bends when these bends are measured directly from the asymmetric bending patterns, without subtracting out the mean shear angle. The asymmetry in development times was previously considered to be evidence against a “biased baseline” mechanism for asymmetric bending waves, in which completely symmetric bending waves develop and propagate on a curved flagellum. Our analysis now shows that the asymmetry in development times can be fully explained by the presence of a sharp static bend near the base of the flagellum, which can confuse the determination of the times of initiation of new bends at the base of the flagellum. Our reinterpretation of these data removes previous objections to the “biased baseline” mechanism for the regulation of bending wave asymmetry by calcium, and supports other evidence favoring a biased baseline mechanism, rather than a “biased switching” mechanism.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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