scholarly journals An Outer Arm Dynein Conformational Switch Is Required for Metachronal Synchrony of Motile Cilia in Planaria

2010 ◽  
Vol 21 (21) ◽  
pp. 3669-3679 ◽  
Author(s):  
Panteleimon Rompolas ◽  
Ramila S. Patel-King ◽  
Stephen M. King
Keyword(s):  
Beat Frequency ◽  
Feedback System ◽  
Ciliary Beat Frequency ◽  
Conformational Switch ◽  
Ciliary Beating ◽  
Similar Phenotype ◽  
Motile Cilia ◽  
Metachronal Waves ◽  
Mechanical Feedback

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 epithelium of the planarian Schmidtea mediterranea to dissect the role of outer arm dynein motors in the metachronal synchrony of motile cilia. We demonstrate that animals that completely lack outer dynein arms display a significant decline in beat frequency and an inability of cilia to coordinate their oscillations and form metachronal waves. Furthermore, lack of a key mechanosensitive regulatory component (LC1) yields a similar phenotype even though outer arms still assemble in the axoneme. The lack of metachrony was not due simply to a decrease in ciliary beat frequency, as reducing this parameter by altering medium viscosity did not affect ciliary coordination. In addition, we did not observe a significant temporal variability in the beat cycle of impaired cilia. We propose that this conformational switch provides a mechanical feedback system within outer arm dynein that is necessary to entrain metachronal synchrony.

scholarly journals PKA induces Ca2+ release and enhances ciliary beat frequency in a Ca2+-dependent and -independent manner

1998 ◽  
Vol 275 (3) ◽  
pp. C790-C797 ◽  
Author(s):  
Alex Braiman ◽  
Orna Zagoory ◽  
Zvi Priel
Keyword(s):  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Ciliary Activity ◽  
Experimental Conditions ◽  
Independent Manner ◽  
Ciliary Beating ◽  
Independent Mechanism ◽  
Intracellular Ca ◽  
Ciliary Beat

The intent of this work was to evaluate the role of cAMP in regulation of ciliary activity in frog mucociliary epithelium and to examine the possibility of cross talk between the cAMP- and Ca2+-dependent pathways in that regulation. Forskolin and dibutyryl cAMP induced strong transient intracellular Ca2+ concentration ([Ca2+]i) elevation and strong ciliary beat frequency enhancement with prolonged stabilization at an elevated plateau. The response was not affected by reduction of extracellular Ca2+concentration. The elevation in [Ca2+]iwas canceled by pretreatment with 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid-AM, thapsigargin, and a phospholipase C inhibitor, U-73122. Under those experimental conditions, forskolin raised the beat frequency to a moderately elevated plateau, whereas the initial strong rise in frequency was completely abolished. All effects were canceled by H-89, a selective protein kinase A (PKA) inhibitor. The results suggest a dual role for PKA in ciliary regulation. PKA releases Ca2+ from intracellular stores, strongly activating ciliary beating, and, concurrently, produces moderate prolonged enhancement of the beat frequency by a Ca2+-independent mechanism.

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

Differential effects of UTP, ATP, and adenosine on ciliary activity of human nasal epithelial cells

2001 ◽  
Vol 280 (6) ◽  
pp. C1485-C1497 ◽  
Author(s):  
Diane M. Morse ◽  
Jennifer L. Smullen ◽  
C. William Davis
Keyword(s):  
Epithelial Cells ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Ciliary Activity ◽  
Maximal Effect ◽  
Ciliary Beating ◽  
Mediated Effects ◽  
Human Nasal Epithelium ◽  
Human Nasal Epithelial Cells ◽  
Sustained Responses

The purinergic regulation of ciliary activity was studied using small, continuously superfused explants of human nasal epithelium. The P2Y2 purinoceptor (P2Y2-R) was identified as the major purinoceptor regulating ciliary beat frequency (CBF); UTP (EC50 = 4.7 μM), ATP, and adenosine-5′- O-(3-thiotriphosphate) elicited similar maximal responses, approximately twofold over baseline. ATP, however, elicited a post-peak sustained plateau in CBF (1.83 ± 0.1-fold), whereas the post-peak CBF response to UTP declined over 15 min to a low-level plateau (1.36 ± 0.16-fold). UDP also stimulated ciliary beating, probably via P2Y6-R, with a maximal effect approximately one-half that elicited by P2Y2-R stimulation. Not indicated were P2Y1-R-, P2Y4-R-, or P2Y11-R-mediated effects. A2B-receptor agonists elicited sustained responses in CBF approximately equal to those from UTP/ATP [5′-( N-ethylcarboxamido)adenosine, EC50 = 0.09 μM; adenosine, EC50 = 0.7 μM]. Surprisingly, ADP elicited a sustained stimulation in CBF. The ADP effect and the post-peak sustained portion of the ATP response in CBF were inhibited by the A2-R antagonist 8-( p-sulfophenyl)theophylline. Hence, ATP affects ciliary activity through P2Y2-R and, after an apparent ectohydrolysis to adenosine, through A2BAR.

scholarly journals Ciliomotor circuitry underlying whole-body coordination of ciliary activity in the Platynereis larva

2017 ◽  
Author(s):  
Csaba Verasztó ◽  
Nobuo Ueda ◽  
Luis A. Bezares-Calderón ◽  
Aurora Panzera ◽  
Elizabeth A. Williams ◽  
...  
Keyword(s):  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Whole Body ◽  
Ciliary Activity ◽  
Ciliary Beating ◽  
Stop And Go ◽  
Multiciliated Cells ◽  
Platynereis Dumerilii ◽  
Catecholaminergic Cells ◽  
Ciliary Locomotion

AbstractCiliated 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 segmental multiciliated cells that regularly display spontaneous coordinated ciliary arrests. We used whole-body connectomics, activity imaging, transgenesis, and neuron ablation to characterize the ciliomotor circuitry. We identified cholinergic, serotonergic, and catecholaminergic ciliomotor neurons. The synchronous rhythmic activation of cholinergic cells drives the coordinated arrests of all cilia. The serotonergic cells are active when cilia are beating. Serotonin inhibits the cholinergic rhythm, and increases ciliary beat frequency. Based on their connectivity and alternating activity, the catecholaminergic cells may generate the rhythm. The ciliomotor circuitry thus constitutes a stop-and-go pacemaker system for the whole-body coordination of ciliary locomotion.

Nasal Mucociliary Transport: New Evidence for a Key Role of Ciliary Beat Frequency

2002 ◽  
Vol 112 (3) ◽  
pp. 570-573 ◽  
Author(s):  
Wilbert M. Boek ◽  
Kees Graamans ◽  
Hanny Natzijl ◽  
Peter P. van Rijk ◽  
Egbert H. Huizing
Keyword(s):  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Mucociliary Transport ◽  
New Evidence ◽  
Ciliary Beat

Effects of ethanol on in vitro ciliary motility

1988 ◽  
Vol 65 (4) ◽  
pp. 1617-1620 ◽  
Author(s):  
D. R. Maurer ◽  
J. Liebman
Keyword(s):  
Beat Frequency ◽  
Slow Motion ◽  
Ciliary Beat Frequency ◽  
Blood Levels ◽  
Ciliary Beating ◽  
Ciliary Motility ◽  
Social Drinking ◽  
High Concentrations ◽  
Ciliary Beat

Consumption of ethanol can impair lung function and slow total lung clearance. High concentrations of ethanol have been shown to slow or arrest ciliary beating. This study examined the effects of concentrations of alcohol comparable to blood levels achieved from social drinking on ciliary beat frequency. We obtained ciliated cells by brushing the trachea of unanesthetized sheep during fiber-optic bronchoscopy. The cells were suspended in a perfusion chamber and physiological conditions were maintained in vitro. Ciliary beat frequency and synchrony were determined by slow-motion analysis of video images obtained by interference contrast microscopy. Metachronal ciliary coordination was observed in all preparations. The ciliary beat frequency was stimulated at ethanol concentrations from 0.01 up to but not including 0.1%, unchanged at 0.5 and 1%, and slowed at 2%. While confirming inhibition of ciliary motility at very high ethanol levels, we observed no acute impairment of ciliary function at ethanol concentrations comparable to those achieved from social drinking. Indeed, we found an unexpected stimulation of ciliary beating at low levels of ethanol. How this alteration in ciliary beating would affect pulmonary clearance remains unknown at this time.

scholarly journals Deep phenotyping, including quantitative ciliary beating parameters, and extensive genotyping in primary ciliary dyskinesia

2019 ◽  
Vol 57 (4) ◽  
pp. 237-244 ◽  
Author(s):  
Sylvain Blanchon ◽  
Marie Legendre ◽  
Mathieu Bottier ◽  
Aline Tamalet ◽  
Guy Montantin ◽  
...  
Keyword(s):  
Primary Ciliary Dyskinesia ◽  
High Speed ◽  
Genetic Disorder ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Central Complex ◽  
Ciliary Beating ◽  
Recovery Stroke ◽  
Biallelic Mutations ◽  
Ciliary Dyskinesia

BackgroundPrimary ciliary dyskinesia (PCD) is a rare genetic disorder resulting in abnormal ciliary motility/structure, extremely heterogeneous at genetic and ultrastructural levels. We aimed, in light of extensive genotyping, to identify specific and quantitative ciliary beating anomalies, according to the ultrastructural phenotype.MethodsWe prospectively included 75 patients with PCD exhibiting the main five ultrastructural phenotypes (n=15/group), screened all corresponding PCD genes and measured quantitative beating parameters by high-speed video-microscopy (HSV).ResultsSixty-eight (91%) patients carried biallelic mutations. Combined outer/inner dynein arms (ODA/IDA) defect induces total ciliary immotility, regardless of the gene involved. ODA defect induces a residual beating with dramatically low ciliary beat frequency (CBF) related to increased recovery stroke and pause durations, especially in case of DNAI1 mutations. IDA defect with microtubular disorganisation induces a low percentage of beating cilia with decreased beating angle and, in case of CCDC39 mutations, a relatively conserved mean CBF with a high maximal CBF. Central complex defect induces nearly normal beating parameters, regardless of the gene involved, and a gyrating motion in a minority of ciliated edges, especially in case of RSPH1 mutations. PCD with normal ultrastructure exhibits heterogeneous HSV values, but mostly an increased CBF with an extremely high maximal CBF.ConclusionQuantitative HSV analysis in PCD objectives beating anomalies associated with specific ciliary ultrastructures and genotypes. It represents a promising approach to guide the molecular analyses towards the best candidate gene(s) to be analysed or to assess the pathogenicity of the numerous sequence variants identified by next-generation-sequencing.

scholarly journals PACRG and FAP20 form the inner junction of axonemal doublet microtubules and regulate ciliary motility

2019 ◽  
Vol 30 (15) ◽  
pp. 1805-1816 ◽  
Author(s):  
Erin E. Dymek ◽  
Jianfeng Lin ◽  
Gang Fu ◽  
Mary E. Porter ◽  
Daniela Nicastro ◽  
...  
Keyword(s):  
Cell Motility ◽  
Electron Tomography ◽  
Structural Studies ◽  
Ciliary Beating ◽  
Ciliary Motility ◽  
Functional Studies ◽  
Cryo Electron Tomography ◽  
Motile Cilia

We previously demonstrated that PACRG plays a role in regulating dynein-driven microtubule sliding in motile cilia. To expand our understanding of the role of PACRG in ciliary assembly and motility, we used a combination of functional and structural studies, including newly identified Chlamydomonas pacrg mutants. Using cryo-electron tomography we show that PACRG and FAP20 form the inner junction between the A- and B-tubule along the length of all nine ciliary doublet microtubules. The lack of PACRG and FAP20 also results in reduced assembly of inner-arm dynein IDA b and the beak-MIP structures. In addition, our functional studies reveal that loss of PACRG and/or FAP20 causes severe cell motility defects and reduced in vitro microtubule sliding velocities. Interestingly, the addition of exogenous PACRG and/or FAP20 protein to isolated mutant axonemes restores microtubule sliding velocities, but not ciliary beating. Taken together, these studies show that PACRG and FAP20 comprise the inner junction bridge that serves as a hub for both directly modulating dynein-driven microtubule sliding, as well as for the assembly of additional ciliary components that play essential roles in generating coordinated ciliary beating.

Effect of pH, Viscosity and Ionic-Strength Changes on Ciliary Beating Frequency of Human Bronchial Explants

1983 ◽  
Vol 64 (4) ◽  
pp. 449-451 ◽  
Author(s):  
Chun Ka Luk ◽  
Mauricio J. Dulfano
Keyword(s):  
Ionic Strength ◽  
Marked Reduction ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Ciliary Activity ◽  
Rapid Loss ◽  
Significant Drop ◽  
Ciliary Beating ◽  
Beating Frequency

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 preserved at NaCl concentrations between 5 g/l (80 mmol/l) and 12 g/l (200 mmol/l), but there was rapid loss at concentrations below 0.5 gA (10 mmol/l). The cilia beat best at viscosities below 1.0 centipoises (1 mN s m−2). Increase of the viscosity gradually decreases CBF with a significant drop at viscosities above 87 millipoises. 4. It is concluded that the above limits may fairly accurately indicate the actual physical characteristics of the periciliary environment (‘sol layer’) in vivo.

scholarly journals Ciliomotor circuitry underlying whole-body coordination of ciliary activity in the Platynereis larva

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Csaba Verasztó ◽  
Nobuo Ueda ◽  
Luis A Bezares-Calderón ◽  
Aurora Panzera ◽  
Elizabeth A Williams ◽  
...  
Keyword(s):  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Whole Body ◽  
Ciliary Activity ◽  
Ciliary Beating ◽  
Stop And Go ◽  
Multiciliated Cells ◽  
Platynereis Dumerilii ◽  
Catecholaminergic Cells ◽  
Ciliary Locomotion

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 segmental multiciliated cells that regularly display spontaneous coordinated ciliary arrests. We used whole-body connectomics, activity imaging, transgenesis, and neuron ablation to characterize the ciliomotor circuitry. We identified cholinergic, serotonergic, and catecholaminergic ciliomotor neurons. The synchronous rhythmic activation of cholinergic cells drives the coordinated arrests of all cilia. The serotonergic cells are active when cilia are beating. Serotonin inhibits the cholinergic rhythm, and increases ciliary beat frequency. Based on their connectivity and alternating activity, the catecholaminergic cells may generate the rhythm. The ciliomotor circuitry thus constitutes a stop-and-go pacemaker system for the whole-body coordination of ciliary locomotion.

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