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  • Articles  (6)
  • flagella  (6)
  • Wiley-Blackwell  (6)
  • Elsevier
  • Institute of Physics
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • Springer Nature
  • 1985-1989  (6)
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  • 1970-1974
  • 1987  (6)
  • Medicine  (6)
  • Sociology
  • History
  • Energy, Environment Protection, Nuclear Power Engineering
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  • Articles  (6)
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  • Wiley-Blackwell  (6)
  • Elsevier
  • Institute of Physics
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
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  • 1985-1989  (6)
  • 1980-1984
  • 1975-1979
  • 1970-1974
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  • Medicine  (6)
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  • Biology  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Stimulation of in vitro motility of Chlamydomonas axonemes by inhibition of cAMP-dependent phosphorylation (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 302-311 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When demembranted axonemes of Chlamydomonas were reactivated with Mg ATP, the proportion of motile axonemes was significantly increased by the preence of either phosphodiesterase (PDE) or protein inhibitor of cAMP-dependent kinase (PKI). The effect of PDE was cancelled by the addition of cAMP. These findings strongly suggest that the axoneme samples have endogenous cAMP, which can reduce the proportion of motile axonemes via phosphorylation. This inhibitory effect of cAMP on Chlamydomonas axonemes is opposite to its stimulatory effect on the axonemal motility in other organisms so far reported. PKI or PDE activated the motility motility either in the absence of Ca2+, when the axonemes beat with an asymmetric waveform, or in 10-5M Ca2+, when the axonemes beat with a symmetric waveform. This cAMP-dependent regulation of motility was observed with the axonemes from which detergent-soluble material had been removed, indicating that the proteins responsible for the regulation still remained in the axonemes. Preliminary in vitro phosphorylation stdies have implicated two polypetides as candidates for the target protein of cAMP-dependent protein kinase: one with a molecular weight of 270 kD and the other with a much larger molecular weight.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080403
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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
    Analysis of the flagellar bending waves of ejaculated ram sperm (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 261-273 
    Details
    ISSN: 0886-1544
    Keywords: spermatozoa ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The variability of flagellar movement, illustrated by the highly heterogenous nature of the ejaculated sperm population of the ram, was analyzed by the use of a stroboscopic technique and an adapted microphotographic 24 × 36 camera system. The multiple-moving-exposures (MME) records give very distinct successive sequences of the flagellar beats and are particularly suitable for the analysis of bend development and propagation along the tail. With this technique, the parameters of the flagellar bending waves of ejaculated ram sperm have been determined. Most of the sperm have planar flagellar beatings; few are rolling under the conditions of observation. The trajectories of the gametes are mostly linear; nevertheless, some have circular paths. The analysis of bending has been focused on two examples for which the difference in the progressiveness ratio was maximum. The circular pathways for ram spermatozoa are linked to an asymmetry between principal and reverse bend probably induced by differences in wave propagation evidenced along the flagellum. A typical sperm flagellar movement may be related either to the conditions of the observations or to some differences in the maturation process of the sperm.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080307
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  • 4
    Electronic Resource
    Electronic Resource
    Topographical relationship between the axonemal arrangement and the bend direction in starfish sperm flagella (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 76-84 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; starfish spermatozoon ; proximal centriole ; bend direction ; bend asymmetry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Since starfish spermatozoa have spherical heads, it is not easy to determine the topographical relationship of the axoneme to the directions of the flagellar bends, the principal, and the reverse bends as defined by Gibbons and Gibbons [J. Cell. Biol. 1972, 63:970-985]. The demembranated spermatozoa are known to take the quiescent “cane” shape with a sharp principal bend at the proximal region of the flagellum in the presence of high concentration of Ca2+. When such spermatozoa were placed on a grid for electron microscopy, fixed with osmic acid vapor, washed with distilled water, and negatively stained with urany1 acetate, the head of the spermatozoon was disrupted and dispersed disclosing the proximal centriole at at the proximal end of the flagellum. The proximal centriole was always found on the concave side of the “cane” -shaped flagella. Electron microscopy of the serial thin sections of intact and demembranated spermatozoa revealed that the doublet microtobules numbers 5 and 6 were contained in the convex edge of the principal bend.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080111
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  • 5
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Flagellar movement of intact and demembranated, reactivated ram spermatozoa (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 375-391 
    Details
    ISSN: 0886-1544
    Keywords: axoneme ; cilia ; flagella ; reactivation ; ram sperm ; high speed video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagellar movement of intact ejaculated ram sperm, and of demembranated models reactivated with ATP, has been studied using high-speed, high-resolution video microscopy.Intact sperm attached to the coverslip by their heads had an average beat frequency of 20.9 Hz and an average wave amplitude of 20.2 μm. There was little difference in the beat frequency or waveform of these sperm and sperm swimming freely near the coverslip or captured by their heads with a micropipette and held far from the coverslip, inducationg that the flagellar waveform of ram sperm is relatively resistant to distorition as a result of immobilization of the head or proximity to a surface. The beat envelope was nearly planar as determined by observations of free-swimming sperm and sperm captured by their head and oriented so they were beating either parallel or perpendicular to the plane of focus.The effect of various conditions for demembranation and reactivation of the sperm were examined. Treatment of sperm with 0.2 % Triton X-100 removed most of their plasma membrane. Under optimal conditions, nearly 100 % of the demembranted sperm reactivated at MgATP2- concentrations ranging from ∼4 μM to ∼20 mM. From ∼ 1 mM to ∼ 10 mM MgATP2-, their beat pattern closely resembled that of intact sperm; beat frequency depended on MgATP2- concentration. Percent motility was maximal between pH 7.5 and 8.0 and decreased sharply below pH 7.0 and avove pH 8.5. The addition of 50 μM cAMP to the reactivation medium had no effect on percent motility or the beat pattern and did not accelerate the initiation of movement.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080410
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