bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microtubule sliding in cilia of the rabbit trachea and oviduct
Authors: Dirksen Ellen Roter , Zeira Michael 
Published: February 2005

AbstractEvidence for active sliding of microtubules during ciliary activity has been demonstrated in a number of organisms: sea urchin sperm flagella, protozoan cilia, and mollusc gill cilia. Although there is evidence that active sliding also occurs in mammalian sperm flagella, there is little or no information on whether active sliding of microtubules also occurs in the short (5‐μm) cilia of the mammalian trachea or oviduct. Since these cilia are important in tracheobronchial clearance and ovum transport, respectively, it has been important to demonstrate that microtubule sliding is also involved in the activity of somatic cilia. Ciliated apical portions (cortices) and cilia were isolated from rabbit trachea and oviduct, using Triton X‐100 to demembranate the cilia. Most of the ciliated cortices reactivated upon addition of ATP, whereas isolated cilia reactivated to a lesser extent. When preparations of cilia were digested with trypsin before or after ATP addition, disintegration of axonemal doublets occurred with about the same frequency as reactivation. These events were recorded using Nomarski optics and dark‐field microscopy. When isolated cilia which had been digested by trypsin and exposed to ATP were also prepared for electron microscopy by negative staining, telescoping of doublet microtubules from axonemes could be shown. These results demonstrate that mammalian somatic ciliary doublet microtubules actively slide in a manner similar to that described for invertebrate cilia.
Effects of Triton‐extraction conditions on beat symmetry of sea urchin sperm flagella
Authors: Okuno M. , Brokaw C. J. 
Published: February 2005

AbstractPotentially 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.
Abnormal myosin heavy chain variant associated with avian muscular dystrophy
Authors: Rushbrook Julie Ivory , Yuan Anna I , Stracher Alfred 
Published: February 2005

AbstractAvian muscular dystrophy is characterized by the degeneration of fast white skeletal muscle fibers, with onset during development. Using a one‐dimensional peptide mapping technique, we have detected two forms of the myosin heavy chain in the fast white fibers of adult domestic chickens, one form characteristic of birds homozygous for muscular dystrophy, the other of their normal controls. Four dystrophic strains carrying the same gene for muscular dystrophy were examined.No differences were detected in the embryonic heavy chain peptide maps of normal and dystrophic chickens, consistent with the developmental onset of the condition. Differences were also absent from the peptide maps of heavy chains from slow red fibers, which are unaffected in dystrophy. No dystrophy‐specific peptide map differences were detected in the three light chains. Analysis of peptide maps of rod and the heavy chain component of subfragment‐1 from normal and dystrophic heavy chains indicates the presence of amino acid sequence differences in the two proteins.
Invited review: The role of nucleotide triphosphate in actin and tubulin assembly and function
Authors: Weisenberg Richard C. 
Published: February 2005

AbstractBoth actin and tubulin, the major proteins of the cytoskeleton, bind nucleotide triphosphate (NTP) and exhibit the phenomenon of “polymerization‐coupled” NTP hydrolysis. In this report I review the nature of polymerization‐coupled NTP hydrolysis, and its possible role in the cellular function of actin and tubulin. Polymerization‐coupled hydrolysis may be viewed as simply reflecting differences in the NTPase activity of free subunit as compared to polymer. Making assumptions concerning the values of various rate constants, it is possible to write expressions for the effects of NTP hydrolysis on the kinetics of polymerization. The role of NTP hydrolysis may be viewed in at least three different ways: (1) Hydrolysis alters the kinetics of assembly and disassembly. This leads to a consideration of the role of subunit flow in microtubule and microfilament function. (2) Hydrolysis is an essentially irreversible step that separates the assembly and disassembly reactions. This suggests a role of NTP in the regulation of polymer content during cellular cycles of assembly and disassembly. (3) NTP may allow transient stabilization of intersubunit bonds. This suggests a role of NTP in nucleation and possible regulation of nonequilibrium states of assembly.
A motile system of singlet microtubules in spermatozoa
Authors: Baccetti B. , Burrini A. G. , Dallai R. , Pallini V. 
Published: February 2005

AbstractIn this report we demonstrate that in the coccid insects Pseudococcus, Phenacoccus, and Planococcus the whole spermatozoon is made up by a nuclear central core surrounded by two complete and one incomplete turns of concentric microtubule palisades. Microtubules of the outer row are linked by a system of short projections 6 nm long; those of the inner row are linked to each other by similar arms; a second system of 6 nm arms links the tubules of each inner row to those of the respective outer row. All these systems of arms are longitudinally spaced every ∼ 12 nm. The motility of this spermatozoon is due to waves progressing from the posterior extremity to the anterior one. By SDS polyacrylamide gel electrophoresis a group of high molecular weight polypeptides is detected, one of which migrates in coincidence with the A dynein band from sea urchin sperm. Our data suggest that occurrence in coccid spermatozoon of a motility due to singlet tubules‐dynein interaction.
Motive force of cytoplasmic streaming during plasmodial mitosis of physarum polycephalum
Authors: Gotoh Kuniyasu , Kuroda Kiyoko 
Published: February 2005

AbstractThe relationship between mitosis and cytoplasmic streaming in the plasmodium of Physarum polycephalum was investigated by simultaneously conducting the following three experiments: (1) identification of the mitotic stages under phase contrast optics, (2) measurement of the rate of oriented migration of the plasmodium on an agar ribbon, and (3) measurement of the motive force of cytoplasmic streaming by the double‐chamber method of Kamiya.The migration of the plasmodium almost stopped during synchronous mitosis and the motive force of the flow decreased to 1/4 of the normal level in this period. Gelation of the endoplasm did not occur during the mitotic period, and thus the cessation of the plasmodial migration must have been caused by the diminution of the motive force responsible for cytoplasmic streaming.
Chromosome movement during meiotic prophase in crane‐fly spermatocytes. I. Observations on living cells and the effects of cyanide and cold treatment
Authors: Lafountain James R. 
Published: February 2005

AbstractMeiotic prophase in spermatocytes of the crane fly, Nephrotoma suturalis, involves both the condensation and the movement of bivalent chromosomes. Since crane flies have only four bivalents that appear highly condensed during late prophase, changes of position and orientation of those bivalents relative to one another can be seen easily in living cells. Chromosome movement during the final 1 to 2 hr of diakinesis was analyzed in detail. Maximal velocities of prophase movements were between 0.1 and 1 μM/min. Metakinetic movements during prometaphase have similar velocities. To assess the physiological basis of prophase movements, experiments employing cyanide and cold treatment were performed. Prophase movements were abolished completely by cyanide, and, for the most part, the velocities of chromosomes in the cold at 2°C and 6°C were less than that of untreated cells at 22°C. The results suggest that prophase movements are energy dependent and may involve an enzyme‐catalyzed process occurring in close association with the nuclear envelope.
Multiple effects of ethanol and 5‐hydroxytryptamine on the gill cilia of mytilus edulis
Authors: Sanderson Michael J. , Satir Peter 
Published: February 2005

AbstractThe lateral (L) cilia on an isolated filament from the gill of Mytilus edulis remain arrested at the end of their recovery stroke (hands up) when perfused with artificial sea water (ASW). The laterofrontal (LF) cilia continue to be active. The addition of 10% ethanol (ETOH) to the ASW perfusate arrests the LF cilia in a hands‐up posture; the L cilia remain undisturbed. By contrast, 10−6 M 5‐hydroxytryptamine (5HT) in ASW activates the L cilia and arrests the LF cilia at the end of their effective stroke (hands down). Continued perfusion with 10% ETOH (v/v) in ASW/5HT restores activity to the LF cilia but arrests the L cilia (hands up). These effects are reversible and independent of external Ca2+.Following the detergent extraction of the filament, all gill cilia are inactive. The addition of 0.2 mM ATP in the presence of low Ca2+ (< 10−7 M) reactivates all model cilia. Under these conditions, 5HT can no longer inhibit the activity of LF cilia and is not required for the activation of the L cilia. This suggests that 5HT acts at a membrane level. An increase in free Ca2+ (> 10−6 M) arrests the L cilia hands up; the LF cilia remain active. Further Ca2+ increase (> 10−3 M) induces hands‐up arrest of the LF cilia, confirming that the Ca2+ threshold of the two ciliary types is different by several orders of magnitude.The addition of 10% ETOH in low Ca2+ to demembranated reactivated cilia arrests the L cilia hands up while the LF cilia continue to beat. Ten percent ETOH appears to interact with the axoneme, mimicking the effect of high Ca2+ and with the membrane to increase Ca2+ permeability and possibly to inactivate 5HT receptors. These results are discussed in terms of axonemal switching mechanisms and the physiological control of filter feeding in the lamellibranch gill.
In situ demonstration of actin in normal and injured ocular tissues using 7‐nitrobenz‐2‐oxa‐1,3‐diazole phallacidin
Authors: Gordon Sheldon R. , Essner Edward , Rothstein Howard 
Published: February 2005

AbstractThe fluorescent derivative of the actin‐binding toxin phallacidin, 7‐nitrobenz‐2‐oxa‐1,3 diazole phallacidin, has been used to cytologically demonstrate the presence of actin in lens epithelium, corneal endothelium, and retinal pigment epithelium. In these noninjured tissues, no stress fibers are observed and fluorescence is confined mainly to an area at or near the cell membrane, although some diffuse cytoplasmic staining can also be seen. However, following injury to either the lens epithelium or corneal endothelium of rats and frogs, stress fibers are detected, but only in those cells that migrate into the wound area. Cells on the periphery of each tissue do not partake in would repair and thus maintain their normal appearance. After the tissue has regenerated, stress fibers disappear, and those cells involved in the injury response return to their normal morphology.When rabbit corneal endothelium is placed in tissue culture, stress fibers are observed as the cells migrate away from the initial explant. Upon reaching confluency, these cells spread out and each is surrounded by thick actin‐containing bands. Furthermore, they exhibit some stress cables within their cytoplasm. This is in contrast to their appearance in vivo where stress fibers are absent and fluorescence is limited to a region near the cell membrane.
Motility of the 6 + 0 flagellum of lecudina tuzetae
Authors: Goldstein Stuart F. , Schrével Joseph 
Published: February 2005

AbstractThe male gametes of the parasitic protozoan, Lecudina tuzetae, have a motile flagellum with a “6 + O” ultrastructure ‘Schrével and Besse, 1975’. These gametes were isolated from the cysts in which they develop and were observed and photographed under a variety of conditions. The flagella beat continuously, without stopping and starting, with a beat period of about 2 sec. They can beat in solutions whose viscosities are greater than 0.5 Nsm−2 (l Nsm−2 = 103 cP). The waveform can be approximated by a series of helical arcs and interconnecting straight regions that travel from the base to the tip. The helical regions have a radius of curvature of 3.2 μm and subtend a final angle of 1.7 radians. The straight portions are 2.0 μm in length. There are two sets of opposing bends, but they do not originate in the same plane. The resulting waveform is an approximately helical coil, with a pitch of 9.8 μm, a pitch angle of 0.6 radian and a peak‐to‐peak amplitude of 2.3 μm. The sense of the coil is left handed. The axoneme twists during beating. The main differences between the movement of this flagellum and that of typical 9 + 2 flagella are a low beat frequency and three‐dimensional bends that produce relatively little forward movement of the cell. Twisting is discussed as a means of discriminating between some types of models of flagellar motility.
Three‐dimensional organization of microtubules and microfilaments of the basal body apparatus of ciliated respiratory epithelium
Authors: Gordon Ronald E. 
Published: February 2005

AbstractThis is a descriptive study showing the three‐dimensional interrelationship of cytoskeletal elements at the apex of ciliated cells of rat respiratory epithelium. Tissue specimens were serially thin sectioned in various planes and examined by transmission electron microscopy. Thicker sections were also cut at various angles and analyzed stereoscopically. Other specimens were cleared of soluble molecules by glycerination or Triton‐X 100 treatment and sectioned as described above. It was found that C microtubules from the triplets of each basal body diverge from the A and B microtubules, run a short distance, and converge at the basal foot. These microtubules or other microtubules arising anew then dispersed deeper into the cytoplasm. The C fibers also interdigitated with other microtubules running perpendicular to them and parallel to the ciliated surface. Ten‐nanometer intermediate filaments were organized in parallel sheets between adjacent basal bodies. Sixnanometer actin filaments were distributed throughout the apical cytoplasm. Neighboring basal bodies were linked to one another by microtubules and microfilaments. Basal bodies from each cell appear to be structured for stability, flexibility, and arranged to operate as a single unit.
Effects of trifluoperazine upon the calcium‐dependent ciliary arrest response of freshwater mussel gill lateral cells
Authors: Reed William , Lebduska Stephen , Satir Peter 
Published: February 2005

AbstractCalmodulin (CaM) isolated from freshwater mussel gill has been shown to be present in fractions derived solely from epithelial cells of whole gill tissue. This CaM has been used to activate bovine brain phosphodiesterase (PDE) and the dose dependence of trifluoperazine‐dihydrochloride (TFP)‐mediated inhibition of activation has been investigated. The dose‐response curve yields an apparent K1 of 20 μM and suggests that at low concentration (up to 40 μM) TFP inhibits PDE activity in the presence of Ca2+, not by direct action on the enzyme, but by a shunt that negates the effect of mussel gill CaM.To determine whether CaM is physiologically significant for ciliary activity in the mussel gill, the effect of TFP upon the Ca2+‐dependent ciliary arrest response of the lateral (L) cells of the gill has been examined. Detergent‐treated permeabilized epithelial L cell models are scored for ciliary activity after transfer to reactivation solutions that vary in their free Ca2+ and TFP content. At 10−5 M free Ca2+ (pCa 5), maximum recovery from arrest is observed for TFP concentrations in the range of 25 to 30 μM. TFP‐mediated recovery from arrest is never complete, suggesting that in the presence of sufficient Ca2+ the drug irreversibly damages a certain fraction of axonemes. At pCa 7 the cilia reactivate and 25–30.
Electromechanical coupling in cilia I. Effects of depolarizing voltage steps
Authors: De Peyer Jacques E. , Machemer Hans 
Published: February 2005

AbstractWe have studied quantitative aspects of ciliary motor responses to membrane depolarization in the ciliate Stylonychia using voltage clamp and high‐speed cinematograhpy techniques and employing computer‐processing methods for evaluation. Depolarizations beyond 4 mV activate the cirri (compound cilia) which are at rest in the absence of a stimulus. The power stroke of activiated cirri is oriented toward the cell anterior. The frequency and duration of beating increase with rising depolarization. With very large positive stimuli (≥ 150 mV) activation of the response is delayed until the end of the voltage step (“off‐response”). The peak frequecy is essentially unaltered during sustained depolarization. The frequency drops exponentially following repolarization of the membrane. The time constant of the decay in ciliary activity rises with the amplitude, not with the duration of the depolarization. The ciliary motor response is most adequately represented by the number of evoked ciliary cycles (ciliary work), and appears to be related to the amplitude of the depolarization.
Electromechanical coupling in cilia II. Effects of hyperpolarizing voltage steps
Authors: De Peyer Jacques E. , Machemer Hans 
Published: February 2005

AbstractWe have studied the motor responses to membrane hyperpolarization of the marginal cirri in Stylonychia using voltage‐clamp, high‐speed cinematography, and computer‐processing techniques. The cirri started beating when voltage step amplitudes rose beyond 5 mV. The power stroke was oriented toward the posterior cell and (hyperpolarizing motor activation). The frequency rose slightly during a voltage step, and decreased with similar rates for 100 ms following the step end. Amplitude and duration of the step tended to increase the motor response of the cirri. The late response declined exponentially. The time constant of the decay rose with the step amplitude. Among three response parameters tested (frequency, duration, number of cycles), the number of evoked ciliary cycles was best correlated with the amplitude of the hyperpolarization. Comparisons with the responses to depolarizing voltage steps reveal similarities in the relaxation of ciliary activity which appears to be uncoupled, in part, from the electric membrane events during the voltage stimulus.
Microtubule capping structures at the tips of tracheal cilia: Evidence for their firm attachment during ciliary bend formation and the restriction of microtubule sliding
Authors: Dentler William L. , Lecluyse E. L. 
Published: February 2005

AbstractThe distal tips of the central pair and A‐microtubules are capped in mammalian and avian tracheal cilia. The capping structures are similar to those found in protozoan cilia and flagella [Dentler, 1981], and consist of a central microtubule cap that links the central microtubules to the membrane or to the ciliary crown and A‐microtubule plugs that insert into the lumen of each of the A‐microtubule plugs is bound to the central microtubule cap by distal filaments. The ends of the central and outer doublet microtubules are tightly bound to the cap in both intact and in demembranated and reactivated tracheal cilia. Analysis of the displacement of the microtubule tips in cilia fixed at various bend angles revealed that the displacements of A‐microtubules are only partially in agreement with those predicted by the sliding filament model [Satir, 1968]. These results are discussed with respect to the regulation of microtubule sliding in capped cilia and the role of the microtubule capping structures in microtubule assembly.
The intracellular movement of endocytic vesicles in cultured granulosa cells
Authors: Herman Brian , Albertini David F. 
Published: February 2005

AbstractLigand binding to cell surface receptors induces rapid internalization of ligandreceptor complexes by receptor mediated endocytosis. We have examined the intracellular movement of endocytic vesicles, induced by the lectin concanavalin A (Con A), in cultured rat ovarian granulosa cells using fluorescence and electron microscopy. Within 20 minutes of ligand treatment at 37°C, numerous Con A‐containing endocytic vesicles form, which migrate to the cell center by 60 minutes. Double label fluorescence microscopy, using fluorescien‐Con‐A and rhodamine immunofluorescent staining of tubulin or vimentin, indicates that during vesicle migration microtubules and 10‐nm filaments are altered in their organization. By 30 minutes, vesicles are associated with microtubule bundles, which subsequently collapse around the nucleus. Similarly, 10‐nm filaments accumulate around the nucleus in conjunction with the perinuclear aggregation of endocytic vesicles. Electron microscopy of Con A‐horseradish peroxidase‐labeled cells demonstrates that endocytic vesicles fuse to form large receptosome‐like structures during intracellular migration and these structures are associated with cytoplasmic microtubules and 10‐nm filaments. Taxol, a drug that stabilizes microtubules, prevents endocytic vesicle translocation to the Golgi region. Nocodazole, which causes microtubule disassembly, results in the collapse of 10‐nm filaments and the central aggregation of endocytic vesicles. The data indicate that the cytoskeleton participates in the directed intracellular movement of endocytic vesicles; the possible subcellular basis for this movement is discussed.
Two different monoclonal antibodies to alpha‐tubulin inhibit the bending of reactivated sea urchin spermatozoa
Authors: Asai David J. , Thompson William C. , Wilson Leslie , Brokaw Charles J. 
Published: February 2005

AbstractTwo monoclonal antibodies reactive for α‐tubulin but not for β‐tubulin have been prepared, characterized in terms of their relative binding to tubulins from differnt sources by a solid‐phase binding assay, immunoautoradiography, and indirect immunofluorescence, and utilized to study flagellar motility. Our results demonstrate that α‐tubulins from different species, and even from different tissues of the same species, are nonidentical. Especially interesting was the observation that one of the antibodies, Ab2, immunofluorescently stained microtubules of chick embryo fibroblast cells, but was completely unreactive for microtubules of rat kangaroo (PtK2) fibroblasts; a different antibody, Ab1, stained both cell types. Results of these and additional experiments clearly show that Ab1 and Ab2 recognize discrete and different epitopes on α‐tubulin.Monoclonal antitubulins Ab1 and Ab2 each inhibited the bend amplitude of reactivated sea urchin spermatozoa without affecting beat frequencies or the ability of the outer doublet microtubules to slide past each other in elastase‐digested models. These results, together with those obtained previously using rabbit polyclonal antitubulin antibodies [Asai and Brokaw, 1980], demonstrate that inhibition of bend amplitude is a common property of antitubulin antibodies and is not due to the binding of antibodies to one specific site on the axoneme. Our results suggest that tubulin subunit conformational changes may occur on the outer doublet lattice and may be integrally involved in the mechanism and control of flagellar bending.