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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 253 (1975), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the intact flagellum, dynein arms produce shearing forces that result in sliding between adjacent doublet microtubules. This sliding can be demonstrated directly by limited digestion of demembranated axonemes with a protease in the presence of MgATP2"; this causes the doublets to slide actively ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 290 (1981), S. 708-710 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our observations on the ultrastructure of the flagellum of M. pusilla (previously named Chromulina pusilla 9) agree well with those of Manton8. The flagellum is ∼5 µm long and has the appearance of a short thick stub terminated by a long thin fibre (Fig. la). The thicker proximal portion ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 206-218 
    ISSN: 0886-1544
    Keywords: sperm motility ; sperm maturation ; flagella ; protein kinases ; protein kinase inhibitor ; cGMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ejaculated ram sperm were demembranated with Triton X-100, separated from the detergent-soluble matrix, and reactivated [San Agustin and Witman (1993): Cell Motil. Cytoskeleton 24:264-273]. The percent motility of models prepared from freshly washed sperm was comparable to that of the washed sample before demembranation, regardless of whether cAMP was included in the reactivation medium. However, demembranated models derived from aging or metabolically inhibited sperm exhibited a lower percent reactivation and required cAMP to attain the level of motility of freshly washed sperm. Cyclic AMP was ∼100 times more effective than cGMP. The requirement for cAMP could be bypassed by addition of porcine heart cAMP-dependent protein kinase (PKA) catalytic subunit to the reactivation medium, demonstrating that cAMP was acting via PKA. The cAMP stimulation of reactivation was not affected by inclusion of the PKA inhibitor PKI(5-24) in the reactivation medium, but was decreased when the models were preincubated with PKI(5-24) prior to reactivation. The cytosol-free models retained 〉90% of the sperm PKA activity; therefore, the PKA appears to be anchored to internal sperm structures. This PKA could not be extracted by cAMP or Triton X-100 alone, but only by cAMP and Triton X-100 in combination. We conclude that cAMP-dependent protein phosphorylation is critical for sperm motility, but that the essential protein phosphate sites turn over slowly under our reactivation conditions, so that the cAMP requirement is apparent only in models prepared from sperm having a low internal ATP or cAMP content. Interestingly, reactivation was rapidly blocked by the peptide arg-lys-arg-ala-arg-lys-glu, which has been reported to be a selective inhibitor of cGMP-dependent protein kinase. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 266-278 
    ISSN: 0886-1544
    Keywords: ATPase ; flagella ; intermediate chains ; vanadate-mediated photolysis ; vertebrate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Outer-arm dynein purified from trout spermatozoa was disrupted by low-ionicstrength dialysis, and the resulting subunits were separated by sucrose density-gradient centrifugation. The intact 19 S dynein, containing the α- an β-heavy chains, intermediate chains (ICs) 1-5 and light chains (LCs) 1-6, yielded several discrete particles: a 17.5 S adenosine triphosphatase (ATPase) composed of the γ-and β-chains ICs 3-5 and LC 1; a 9.5 S complex containing ICs 1 and 2 together with LCs 2, 3, 4, and 6; and a single light chain (LC 5), which sedimented at ∼4 S. In some experiments, ICs 3-5 also separated from the heavy chain complex and were obtained as a distinct subunit. Further dissociation of the 17.5 S particle yielded a 13.1 S ATPase that contained the β-heavy chain and ICs 3-5. The polypeptide compositions of the complexes provide new information on the intermolecular associations that occur within dynein.Substructural features of the trout dynein polypeptides also were examined. The heavy chains were subjected to vanadate-mediated photolysis at the V1 sites by irradiation at 365 nm in the presence of Mg2+, ATP, and vanadate. Fragment pairs of relative molecular mass (Mr) 245,000/185,000 and 245,000/170,000 were obtained from the α- and β-heavy chains, respectively. Photolysis of these molecules at their V2 sites, by irradiation in the presence of vanadate and Mn2+, yielded fragments of Mr 160,000/270,000 and 165,000/250,000, respectively. These values confirm that the α- and β-heavy chains have masses of 430,000 and 415,000 daltons, respectively.Immunological analysis using monoclonal antibodies revealed that one intermediate chain from trout dynein (IC 2) contains epitopes present in two different intermediate chains from Chlamydomonas dynein. This indicates that specific sequences within the dynein intermediate chains have been highly conserved throughout evolution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 375-391 
    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
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 525-547 
    ISSN: 0886-1544
    Keywords: cilia ; flagella ; ATPases ; dynein ; Chlamydomonas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extraction of isolated, demembranated flagellar axonemes of Chlamydomonas reinhardii with 0.6 M KCl solubilized 77-92% of the total axonemal Mg++ or Ca++-ATPase activity, which sedimented as 18S and 12S peaks in sucrose density gradients. The ATPases of these two peaks were further purified by hydroxyapatite (HAP) column chromatography. The ATPase activity of the 18S peak eluted from the HAP column as a single peak coinciding with the protein peak. The HAP purified 18S ATPase had a specific activity of ∼2.0 ± 0.5 μmoles Pi hydrolyzed min/mg and was associated with four high molecular weight (HMW) polypeptides of ∼ 310,000-340,000 daltons, two intermediate molecular weight (IMW) polypeptides of 78,000 and 69,000 daltons, and eight low molecular weight (LMW) polypeptides of 7,800-19,600 daltons. When the 12S sucrose gradient peak together with a trailing shoulder were chromatographed on HAP, the ATPase activity was eluted in two peaks designated 12S and 10.5S on the basis of the sedimentation properties of their associated polypeptides. The 12S peak contained a single dynein ATPase having a specific activity of ∼ 0.6 ± 0.3 μmoles Pi hydrolyzed min/mg and associated with ∼ 330,000-, 21,700-, and 18, 100-dalton polypeptides. The 10.5S peak contained several high, intermediate, and low molecular weight polypeptides; of these, on HMW polypeptide and one 28,700-dalton polypeptide correlated well with the ATPase activity. The purified ATPases had no polypeptides in common; each therefore represents a discrete dynein. Based on protein recovered in the purified fractions, 18S dynein represents ∼ 9.2% of the total axonemal protein; 12S dynein represents ∼ 4.7% of the axonemal protein.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 264-273 
    ISSN: 0886-1544
    Keywords: sperm motility ; axonemes ; sperm fractionation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A procedure for preparing cytosol-free ram sperm models was developed. Sperm are introduced to a Triton X-100-containing demembranation medium layered on top of a discontinuous Percoll gradient. After brief exposure to the demembranating solution, the sperm are separated from the detergent-soluble components by centrifugation through a 55% Percoll layer, finally collecting on top of a 90% Percoll cushion from where they are recovered. Optimum conditions consisted of Triton X-100 at 0.20% and a demembranation time of 35 sec. Cross-sections of midpieces and principal pieces of the demembranated sperm were examined by electron microscopy. With 0.20% Triton X-100 in the demembranation medium, 86% of the cross-sections showed no plasma membranes and the rest had broken plasma membranes. The remaining tail structures appeared to be morphologically intact. Assay of phosphoglucose isomerase as a marker enzyme confirmed that at least 98% of the cytosolic protein was removed. Ram sperm models obtained by this procedure could be reactivated, and the percent motility and beat parameters were similar to those of the intact sperm. Reconstitution with the detergent-soluble components was neither required for, nor enhanced, reactivation. Therefore, demembranated ram sperm do not require a detergent-soluble protein factor for reactivation. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 97-109 
    ISSN: 0886-1544
    Keywords: calcium ; flagellar movement ; mechanotransduction ; mechanoshock response ; Spermatozopsis similis ; video analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The biflagellate green alga Spermatozopsis similis exhibits a remarkable avoidance reaction in addition to the photophobic or stop response characteristic of such algae. S. similis normally swims forward with its anteriorly attached flagella directed posteriorly and propagating sine-like waves from base to tip. Upon contact with surfaces or other cells, S. similis responds with rapid backward swimming, covering distances of up to 50 μm in 140 to 220 msec. This reaction, which we term the mechanoshock response, also can be triggered by vigorous mechanical stimulation, but not by physiological light intensities. It consists of 3 phases: (1) a rapid acceleration phase with average duration of 31 msec; (2) a phase of about 66 msec with constant high speed (maximal velocities of 〉 600 μm·sec-1) or slow deceleration; and (3) a deceleration phase of ∼ 83 msec, followed by a stop or short period of circling. The cells then resume forward swimming in a random direction. Prior to the mechanoshock response the flagella rapidly are brought together into a close parallel configuration extending anteriorly of the cell body. They then appear to propel the cell by undulatory beating, while the cell describes a pronounced helical path. Small decreases in the extracellular Ca2+ concentration, as well as low concentrations of Ba2+, strongly suppress the probability of this phobic reaction. We conclude that this mechanoshock response involves large Ca2+ influxes, probably mediated by mechanosensitive and/or stretch-activated ion-channel(s). © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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