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At least 955 records · Page 53Linked to original sources
PubMed1982

The control of anthozoan cilia by the basal apparatus.

The ciliary basal apparatus in the pharynx of the sea anemone, Calliactis parasitica (Couch), is composed of two centrioles, a single striated rootlet at least 20 microns long, and a basal foot, to the tip of which is attached a bundle of microtubules leading to the rootlet. When the basal apparatus is sectioned in the plane of the ciliary power-stroke, the distal centriole, with which the cilium base is continuous, is rarely found to be erect. The orientation of the distal centriole is determined by bending in the basal apparatus. Bending occurs only in the plane of the ciliary power-stroke towards the side from which the basal foot projects, and it is closely correlated with membrane buckling in the belt desmosome region of the cell apex. Associated with the belt desmosome, but not directly with the basal apparatus, are bundles of filaments. These filaments are of two size classes, 5-6 and 10 nm in diameter. A model is presented in which the 5-6 nm filaments form the basis of a contractile system which mediates membrane buckling in the region of the belt desmosome. This action effectively shortens the cell apex and thus forces the apparatus to bend. The precise reorientation of the distal centriole is a result of the mechanical properties of the basal apparatus.

Animals↗
PubMed1988

From cilia and flagella to intracellular motility and back again: a review of a few aspects of microtubule-based motility.

Ciliary or flagellar movement is the model of microtubule-dependent motility, the best studied at the molecular level. It is based on the relative sliding of outer doublets of microtubules that are linked at their proximal end to the basal structure and interconnected by associated proteins, among which dynein ATPase is at the origin of the movement. It is regulated from inside and outside media by various diffusible factors such as Ca2+, cyclic adenosine monophosphate (cAMP), polypeptides and so on (see other conferences presented during this meeting). Other motility processes are based on microtubules: vesicle and organelle transport through the cytoplasm (axonal flow in neurons, pigment granule movements in fish chromatophores, movements of particles along heliozoan axopods, etc.) could be mediated by microtubule motors such as kinesin or MAP 1C. Kinesin and MAP 1C, like dynein, are proteins that bind to microtubules and show an ATPase activity associated with force production. They differ from each other by their structure, and biochemical and pharmacological properties. The movements of chromosomes during mitosis and meiosis have long been studied, but are still poorly understood at the molecular level; this topic will be discussed in the light of recent data. Other constituents of the cytoskeleton are certainly involved in cellular motility: actin microfilaments and their motor myosin, intermediate filaments, non-actin filaments, all organized around the Microtubule Organizing Center (MTOC). As more information becomes available, it seems increasingly obvious that these various networks are closely interconnected and that each component probably modulates, resists, or favors properties of its partners, contributing to cellular and intracellular motility.

Animals↗
PubMed2004

Odontoblast primary cilia: facts and hypotheses.

Odontoblasts, the cells responsible for the dentine formation, are organized as a single layer of highly polarized and differentiated post-mitotic cells along the interface between the dental pulp and the mineralized tubules. They lay down the physiological secondary dentine throughout the life of the teeth. Odontoblasts play a central role in the transportation of calcium to the dentine and they possibly mediate early stages of sensory processing in teeth. A primary cilium, 9+0 configuration, have been regularly identified in a supra nuclear location. Calbindin D28k has been detected at the base of the cilium membrane. The cilium structure was positive with detyrosinated alpha tubulin antibodies in vivo and in cultured human odontoblasts. Transcripts of tektin, a protein involved in ciliogenesis, were expressed in vitro. The putative role of the primary cilium constituting a critical link between external teeth stimuli and odontoblast responses is extensively discussed.

Calbindin 1↗
PubMed2005

High expression of the taurine transporter TauT in primary cilia of NIH3T3 fibroblasts.

Taurine, present in high concentrations in various mammalian cells, is essential for regulation of cell volume, cellular oxidative status as well as the cellular Ca2+ homeostasis. Cellular taurine content is a balance between active uptake through the saturable, Na(+)-dependent taurine transporter TauT, and passive release via a volume-sensitive leak pathway. Here we demonstrate that: (i) TauT localizes to the primary cilium of growth-arrested NIH3T3 fibroblasts, (ii) long-term exposure to TNF(alpha) or hypertonic sucrose medium, i.e., growth medium supplemented with 100 mM sucrose, increases ciliary TauT expression and (iii) long-term exposure to hypertonic taurine medium, i.e., growth medium supplemented with 100 mM taurine, reduces ciliary TauT expression. These results point to an important role of taurine in the regulation of physiological processes located to the primary cilium.

3T3 Cells↗
PubMed2006

Analysis of the orientation of primary cilia in growth plate cartilage: a mathematical method based on multiphoton microscopical images.

The chondrocytic primary cilium has been hypothesized to act as a mechano-sensor, analogously to primary cilium of cells in epithelial tissues. We hypothesize that mechanical inputs during growth, sensed through the primary cilium, result in directed secretion of the extracellular matrix, thereby establishing tissue anisotropy in growth plate cartilage. The cilium, through its orientation in three-dimensional space, is hypothesized to transmit to the chondrocyte the preferential direction for matrix secretion. This paper reports on the application of classical mathematical methods to develop an algorithm that addresses the particular challenges relative to the assessment of the orientation of the primary cilium in growth plate cartilage, based on image analysis of optical sections visualized by multiphoton microscopy. Specimens are prepared by rapid cold precipitation-based fixation to minimize possible artifactual post-mortem alterations of ciliary orientation. The ciliary axoneme is localized by immunocytochemistry with antibody acetylated-alpha-tubulin. The method is applicable to investigation of ciliary orientation in different zones of the growth plate, under either normal or altered biomechanical environments. The methodology is highly flexible and adaptable to other connective tissues where tissue anisotropy and directed secretion of extracellular matrix components are hypothesized to depend on the tissue's biomechanical environment during development and growth.

Algorithms↗
PubMed2004

Establishing a connection between cilia and Bardet-Biedl Syndrome.

Bardet-Biedl Syndrome (BBS) is a gentic disorder with primary features of retinal dystrophy, obesity, polydactyly, structural and functional renal abnormalities, and learning disabilities. In addition to displaying remarkable pleiotropy, BBS is a heterogeneous disorder with linkage to at least eight loci. The identification of the first five BBS genes provided little insight into BBS protein function. Ansley at al. have now identified a sixth BBS gene (BBS8) and provide evidence that the BBS8 protein and other BBS proteins localize to the basal body of ciliated cells, suggesting that BBS is a ciliary dysfunction disorder.

Bardet-Biedl Syndrome↗
PubMed2005

Effects of salmeterol on cilia and mucus in COPD and pneumonia patients.

The present study was performed to evaluate the effects of salmeterol xynaphoate on ciliary beat frequency (CBF) of nasal epithelium and on rheological parameters of tracheobronchial mucus. We studied 10 steady-state COPD patients, eight patients with community-acquired pneumonia and eight healthy subjects as controls. They underwent a nasal brushing of the inferior turbinate to study the CBF in basal conditions and following application of salmeterol at 10(-5), 10(-6), 10(-7) and 10(-8) M concentrations directly to the epithelial samples. We also collected sputum samples, in COPD patients only, by the technique for "protected expectoration" for the rheological assessment in basal conditions and following addition of salmeterol at 10(-5), 10(-6), 10(-7) and 10(-8) M concentrations. Only samples with basal viscosity values higher than 2000 mPa/s were admitted. Our results confirmed previous studies that demonstrate a ciliostimulating effect induced by salmeterol. The mean basal CBF was 11.18 +/- 0.75 Hz in control subjects, while the pathological subjects showed a markedly lower basal values: 8.64 +/- 0.88 Hz (p = 0.000) and 8.83 +/- 0.68 Hz (p = 0.000), in COPD and pneumonia patients, respectively. Salmeterol induced ciliostimulation in both patients groups as well as the healthy controls. The maximum increase in CBF, highly significant, was obtained at 10(-6) M concentrations of salmeterol, while this effect decreased at lower concentrations. Regarding the action of salmeterol on rheological parameters, a direct effect of salmeterol on mucus cannot been demonstrated and the described beneficial clinical effects on mucociliary clearance occurring in vivo are probably related to an indirect effect of stimulation of ciliary beat. This preliminary study suggests that, in addition to COPD, salmeterol could be a useful therapeutic agent in pneumonia also, for its positive effect on ciliary movement other than bronchodilation, but this finding needs further investigations.

Albuterol↗
PubMed1989

Synchronization between beating cilia.

A novel quantitative parameter is proposed to define and measure the degree of synchronization between two small ciliary areas. These areas can be close to or far from one another. The Pearson correlation factor is used to define the degree of synchronization by a single number. This approach is based on a computerized, dual photoelectric method which simulataneously measures the scattered light from two small areas on the ciliary epithelium or its tissue culture. The measurements were performed on tissue culture from frog's palate epithelium. It was found that: (a) the degree of synchronization decreases, as a function of distance; (b) the correlation is fairly high even at relatively large separations, when measured on the same patch; (c) on a given patch the synchronization factor is independent of the direction of the metachronal wave; (d) close disconnected ciliary cells exhibit fairly high correlation; (e) disconnected randomly choosen ciliary cells at relatively large separation distances exhibit relatively low correlation, smaller by a factor of 2 than the correlation factor at the same distances when measured along the metachronal wave; (f) the average frequencies' ratio and the metachronal wavelength can be used as first-order indicators of ciliary synchronization; (g) there is a spread of metachronal wavelengths even over a single well-organized patch.

Animals↗