Ciliated surfaces harbouring synchronously beating cilia can generate fluid flow or drive locomotion. In ciliary swimmers, ciliary beating, arrests, and changes in beat frequency are often coordinated across extended or discontinuous surfaces. To understand how such coordination is achieved, we studied the ciliated larvae of Platynereis dumerilii, a marine annelid. Platynereis larvae have segme...

www.sciencemag.org SCIENCE VOL 325 28 AUGUST 2009 1037 COVER Pseudocolored scanning electron micrograph (magnification ~34,000x) of the surface of mouse airway epithelia showing cilia protruding from epithelial cells; short protrusions in the foreground are microvilli from a nonciliated cell. In human airway epithelia, these motile cilia bear receptors that detect bitter compounds and signal th...

Nasal ciliary function and mucociliary clearance were studied in patients with cystic fibrosis and in three control groups. Ciliary beat frequency and nasal clearance time were measured in groups of 10 subjects with cystic fibrosis, sinusitis and bronchiectasis and age and sex-matched control subjects. Ciliary beat frequency was also measured in normal subjects matched as bronchiectasis control...

Motile cilia mediate the flow of mucus and other fluids across the surface of specialized epithelia in metazoans. Efficient clearance of peri-ciliary fluids depends on the precise coordination of ciliary beating to produce metachronal waves. The role of individual dynein motors and the mechanical feedback mechanisms required for this process are not well understood. Here we used the ciliated ep...

In the gymnostome ciliate Didinium nasutum, swimming behaviour depends upon the cyclic activity of about 3000 cilia. The normal beating mode, resulting in forward swimming of the cell, is characterized by a posteriad effective beat (18 left of the longitudinal axis) at a frequency of approximately 15 Hz. Activation of depolarization-sensitive ciliary Ca2+ channels leads to an increase in intrac...

We have examined the effect of adding elastase positive sputum from six patients with purulent bronchiectasis on the ciliary beat frequency of nasal epithelium from normal subjects. Control studies of cilia suspended in tissue culture medium showed little change in ciliary beat frequency over six hours. Cilia incubated in elastase positive secretions, however, showed a considerable decrease in ...

Despite the in vitro ciliotoxicity of tobacco smoke and the abnormal mucociliary clearance found in smoking related chronic bronchitis, studies of mucociliary clearance in healthy smokers have produced variable results. The nasal mucociliary clearance of saccharin and the in vitro nasal ciliary beat frequency were studied in healthy smokers and non-smokers. One of 29 smokers had a nasal mucocil...

1. Ciliary activity is significantly influenced by chemical and physical properties of the liquid medium in which the cilia beat. 2. We studied the effect of changes in pH, ionic strength and viscosity on the ciliary beat frequency (CBF) of explants of human respiratory mucosa. 3. Optimal CBF was elicited at pH 7 . 0-9 . 0, with a marked reduction of CBF outside these limits. The CBF was well p...