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  • 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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    Paper (German National Licenses)
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  • 2
    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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    Paper (German National Licenses)
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  • 3
    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
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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