Ciliary Cycle Research Articles

Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis.

Corrigendum2 May 2016free access Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis Tamara Reyes-Robles Tamara Reyes-Robles Search for more papers by this author Ashira Lubkin Ashira Lubkin Search for more papers by this author Francis Alonzo III Francis Alonzo III Search for more papers by this author D Borden Lacy D Borden Lacy Search for more papers by this author Victor J Torres Victor J Torres Search for more papers by this author Tamara Reyes-Robles Tamara Reyes-Robles Search for more papers by this author Ashira Lubkin Ashira Lubkin Search for more papers by this author Francis Alonzo III Francis Alonzo III Search for more papers by this author D Borden Lacy D Borden Lacy Search for more papers by this author Victor J Torres Victor J Torres Search for more papers by this author Author Information Tamara Reyes-Robles, Ashira Lubkin, Francis Alonzo, D Borden Lacy and Victor J Torres EMBO Reports (2016)17:780-780https://doi.org/10.15252/embr.201670010 This article corrects the following: Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis08 February 2016 ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InMendeleyWechatReddit Figures & Info The authors of the above article regret a mistake in the labeling of the LukABmut2 mutant in Figure 4A and Table EV1. The correct mutated residues are 130–134 instead of residues 122–126 indicated in the current version of the article. Figure 4. Download figure Download PowerPoint The correct Figure 4A is presented here, and the correct Table EV1 is now available online. The results and conclusions of the article remain unchanged. Supporting Information Table EV1 (MS Excel, 40.2 KB) Next ArticlePrevious Article Read MoreAbout the coverClose modalView large imageVolume 17,Issue 5,May 2016Cover: Schematic representation of the role of Kv10.1 during the ciliary cycle. Expression of Kv10.1, which occurs during G2 and M phases of the cell cycle, promotes disassembly of the primary cilium. From Araceli Sánchez, Diana Urrego and Luis A. Pardo: Cyclic expression of the voltage‐gated potassium channel KV10.1 promotes disassembly of the primary cilium. For detail, see Article on page 708. (Artistic rendition by Uta Mackensen) Volume 17Issue 51 May 2016In this issue FiguresRelatedDetailsLoading ...

Tubulohelical membrane arrays: From the initial observation to the elucidation of nanophysical properties and cellular function

Lipids undergo self-assembly to form ordered nonlamellar, nanoperiodic arrays both in vitro and in vivo. While engineering of such membrane arrays for technical devices is envisaged, we know little about their cellular function. Do they represent building blocks of an inherent cellular nanotechnology? Prospects for answering this question could be improved if the nanophysical properties of the membrane arrays could be studied in the context of specific cellular functions. Therefore, we draw attention to exceptional complex membrane arrays found in the renal epithelial cell line PtK2 that could provide perfect conditions for both biophysical and cell functional studies. The so-called tubulohelical membrane arrays (TUHMAs) combine nanoperiodicity of lipid membranes with that of helix-like proteinaceous core structures. Strikingly, they show several characteristics of dynamic, microtubule-associated single organelles. Our initial data indicate that TUHMA formation occurs in the depth of the cytoplasm under participation of cytoplasmic nucleoporins. Once matured, they may fuse with the nuclear membrane in polarized positions, either perpendicularly or in parallel to the nucleus. As a starting point for the initiation of functional studies we found a connection between TUHMAs and primary cilia, indicated by immunolabeling patterns of detyrosynated tubulin and cytoplasmic nucleoporins. We discuss these observations in the context of the ciliary cycle and of the specific requirement of ciliated renal epithelial cells for oriented cell division. Finally, we raise the question of whether putative nanooptical properties of TUHMAs could serve for communicating orientation between dividing cells.MCS codes: 92C37, 92C05, 92C50

Ciliary beating in three dimensions: Steps of a quantitative description

We document a novel approach for quantitative assessment of ciliary activity, exemplified in rapid three-dimensional cyclic motion of the frontal cirri of Stylonychia. Cells held under voltage-clamp control are stimulated by step pulses to elicit reproducible hyperpolarization- or depolarization-induced ciliary motor responses. High-speed video recording at 200 fields per second is used for imaging ciliary organelles of the same cell in two perspectives: the axial view and, following cell rotation by 90 degrees, the lateral view. From video sequences of typically 1 s, the contours of the cirral images are determined and digitized. Computer programs are established to (1) reduce an observed image to a "ciliary axis", (2) sort series of axes by template to generate an averaged ciliary cycle in 2D-projection, and (3) to associate the generalized axial and lateral 2D-images for generation of a sequence of three-dimensional images, which quantitatively represent the cycle in space and time. The method allows us to produce predetermined perspectives of images selected from the ciliary cycle, and to generate stereo views for graphical representation of ciliary motion. The approach includes a potential for extraction of the complete microtubular sliding program of a cilium under reproducible electric stimulation of the ciliary membrane.

The ciliary cycle during hyperpolarization-induced activity: an analysis of axonemal functional parameters.

Motor responses of the frontal cirri of the ciliate Stylonychia were recorded at the axial view of the ciliary base with high-speed cinematography. Voltage-clamp applying sustained hyperpolarizing voltage steps was used to explore the properties of the ciliary cycle modulated by the membrane potential. Upon hyperpolarization between -1 and -13 mV, a previously inactive frontal cirrus reoriented from a neutral posture and started beating so that the axis of the beating cone of a proximal cirral segment assumed an orientation near 100 degrees (proceeding counterclockwise from posterior = 0 degrees) and inclination near 60 degrees (0 degrees = perpendicular to the cell surface). The major beating amplitude was limited to about 150 degrees. Increasing hyperpolarization increased the spatial polarity of the cycle (ratio of major over minor amplitude, from 2 to 2.4). Rates of the power stroke increased with hyperpolarizations up to -4 mV but were consistently smaller than those of the return stroke during the ciliary cycle (ratio: 0.4 to 0.6; = temporal polarity). Comparison of different hypothetical beat forms (0-shape, D-shape, and egg-shape) showed that the orientation-time data are the major determinants of the angular velocity and rate of reorientation of the cilium during the cycle. Geometric transformation of these data led to descriptions of the cycle of a proximal ciliary segment in terms of active sliding velocities and rates of unidirectional sliding translocation between identified doublets. Three voltage-sensitive functional parameters of the cilium--the inclination (which is noncyclic) and the rates of active sliding and sliding translocation (both of which are cyclic in nature)--are discussed as generating the spatial and temporal properties of the ciliary beat.

Axial-view recording: An approach to assess the third dimension of the ciliary cycle

High-frequency cine data of the frontal cirri of Stylonychia viewed parallel to the ciliary base (“axial view”) have been geometrically analyzed so as to isolate a steady inclination of the proximal shaft during the ciliary cycle. Correction for this inclination allows assessment of the pathway of the shaft during the cycle and thereby parameters such as the directional change rate, the angular velocity, and the rate of reorientation movement of the cilium. A model is proposed which shows the implications of cyclic ciliary reorientations for the circular translocation of the activation of active sliding of axonemal doublets.

Parameters of the ciliary cycle under membrane voltage control

AbstractAxial views of depolarization‐ and hyperpolarization‐dependent activation of the frontal cirri of Stylonychia were cinematically recorded at high rate (250 frames/s) under voltage‐clamp. Images of a cirrus performing the cycle were processed by using computer assistance. In responding to the polarity and amplitude of the voltage signal, a cirrus inclines proximally with a particular angle and orientation. The ciliary cycle–always counterclockwise–is superimposing upon steady inclination. Correction for inclination allowed the assessment of the directional change rate and, after inclusion of the amplitude data, the determination of the ciliary angular velocity during the cycle. The method serves to isolate a new ciliary parameter: inclination, and to register precisely parameters of the cycle which may be meaningful for the understanding of the sliding mechanism.

Electromechanical coupling in cilia II. Effects of hyperpolarizing voltage steps

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.

Electromechanical coupling in cilia I. Effects of depolarizing voltage steps

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.

Ciliary activity and the origin of metachrony in Paramecium: effects of increased viscosity.

ABSTRACT In forward-swimming Paramecium the direction of metachronal wave propagation is turned progressively clockwise from forward-right to backward-left if the viscosity of the medium is increased to more than 100 cP. With increasing viscosity the direction of the power stroke is turned clockwise at a lower rate than the direction of waves. This leads to a gradual transformation of the dexioplectic metachrony toward a symplectic pattern. As viscosity is raised the polarization of the ciliary cycle in time and space is progressively reduced, so that the beat becomes increasingly helicoidal. Metachronal coordination gradually breaks down at viscosities of more than about 100 cP, but is retained better at the anterior end of the cell than in more posterior regions. At viscosities above 12 cP the left-handed swimming helix of Paramecium is changed into a right-handed helix. This is produced primarily by the viscositydependent clockwise shift in the direction of the power stroke from backward-right to backward-left. The frequency of peristomal cilia (32/s. at 20 °C) decreases with rising viscosity. Under constant conditions, a posteriorly directed gradient of decreasing frequency can be observed with the stroboscope. Raising the viscosity leads to an increase of the average wavelength from 10·7 µm at 1 cP to 14·3 µm at 40 cP. In the same range of viscosity the wave velocity, which is the product of frequency and wavelength, is reduced from 340 to 200 µm/s, since the drop in frequency exceeds the increase in wavelength. The wave velocity tends to be stabilized by reciprocal relations between frequency and wavelength, if all other factors are kept constant. However, the wavelength is found to be different in forward-swimming and backward-swimming animals at 40 cP without a change in frequency (14·1 bps; 14·3 compared to 12·7µm). This is explained if the metachronal wavelength is increased by decreasing polarization of the ciliary cycle. A working hypothesis is put forward which explains the origin of a metachronal system by the distribution of forces parallel to the cell surface produced by polarized or unpolarized cycles of ciliary movement.

A method for determination in vivo of the rate of ciliary beat and mucous flow in the trachea.

Summary.A method is described by which simultaneous determination can be made of the rate of ciliary beat and that of the tracheal flow of mucus in small living mammals (rats and guinea pigs). The body temperature and the temperature and humidity of the environmental air can be varied. All influence of foreign substances such as saline solutions is avoided. The various phases of a single ciliary cycle are registered with a special camera. The method also permits study of the acute and chronic effects on the mucosa of different substances. Some experiments with SO2 are briefly reported.