Control of ciliary beat by calcium: the effects of lindane, a potent insecticide

The ciliary beat and cell motility of Dunaliella, a biflagellate unicellular green alga, have been studied by means of computer analysis of high-speed microcinematography and laser doppler velocimetry. Lindane was found rapidly to inhibit cell velocity in less than 5 min. and in a dose-related manner. After the initial 5-min. period, inhibition remained nearly stable for at least 3 hr. The waveform of the ciliary beat was not uniformly affected by lindane and only the effective stroke was greatly slowed down. The recovery stroke was not significantly modified, and the general form of the wave did not seem to be altered. Bending parameters automatically measured from high-speed movies showed that lindane induced a considerable lengthening of the initiation phase of wave propagation. Since lindane interacts specifically with calcium transport and can induce an increase in cytoplasmic calcium, the strong effect of lindane on ciliary beat is probably correlated with a modification of the calcium balance of the cell. These results support the hypothesis of a control of bend initiation by calcium.     

Ciliary beat and cell motility of Dunaliella: computer analysis of high speed microcinematography

A high-speed microcinematographic study was performed on the biflagellate unicellular alga Dunaliella. A frame-by-frame analysis has shown that the two flagella never beat at the same frequency. For a better characterization of the bending pattern of the two flagella, a new automated method of image analysis has been developed. The method allowed an automatic acquisition of a line characterizing the Dunaliella flagellum and its mathematical modelling. From this model, some binding parameters could be automatically measured, which have permitted determination of the velocities of formation and propagation of flagellar waves and the variation of the curvature radius of the bends between the two flagella. Both flagella showed a similar pattern of ciliary beat. The most important difference was the lengthening of the initiation phase for the slower flagella.     

Ciliary Ultrastructure In Nasal Brushings

Normal ciliary ultrastructure is thought to be necessary for effective function. There has been little or no attempt to quantify ultrastructural abnormalities in nasal disease and assess their significance. In this study we measured nasal ciliary function and examined ciliary ultrastructure in nasal brushings from 35 patients with perennial nasal symptoms refractory to treatment. Ultrastructural defects included microtubular abnormalities, compound cilia and ciliary ‘blebs’. the incidence of abnormal cilia was 16.7%, compared with 9% in controls, but there was only a poor correlation between ultrastructural defects and ciliary beat frequency. One patient had primary ciliary dyskinesia (PCD) with a typical clinical history and immotile cilia. However, only secondary ultrastructural abnormalities were seen. We have been unable to show that ciliary ultrastructural defects form the basis of impaired function. In patients with suspected PCD, nasal brushings should be taken for functional and ultrastructural studies; ideally, a further sample should be obtained for examination of possible primary ultrastructural abnormalities.     

Hysteresis modeling for calcium-mediated ciliary beat frequency in airway epithelial cells

A hysteresis model is proposed to describe calcium-mediated Ciliary beat frequency (CBF) in airway epithelial cells. In this dynamic model, the kinetics of coupling between calcium and CBF is posited as a two-step configuration. First, Ca²⁺ directly binds to or indirectly acts on the axonemal proteins to modulate the activity of axonemal proteins. This step can be modeled by a Hill function in biochemistry. In the second step, the activity of axonemal proteins interacts with the sliding velocity of axonemal microtubules, the equivalent to regulating the CBF. The well-known Bouc-Wen model for hysteresis in mechanical engineering, which can only generate the stable clockwise hysteresis loops, is modified to describe the counter clockwise hysteresis loops commonly observed in the biological experiments. Based upon this new hysteresis model, the dynamic behavior of calcium-regulated CBF in epithelial airway cells is investigated through simulation studies. The numerical results demonstrate that the CBF dynamics in airway epithelial cells predicted by the hysteresis model is more consistent with the experimental observations than that predicted by previous static model in the literature.     

Modulation of cell calcium signals by mitochondria

It is now clearer and clearer that mitochondria play a role, and perhaps an active role, in cell calcium signalling. The fact that mitochondria can exhibit a Ca^2+>-induced Ca^2+> release (mCICR, Ichas et al. [37]) reinforces this concept and makes the mitochondria an essential element in the relay of Ca^2+> wave propagation. It must be emphasized that the modulation of cell Ca^2+> signals by mitochondria depends upon their energetic status, thus making mitochondria an essential link between energy metabolism and calcium signalling inside the cell.     

Losing the beat: deficits in temporal coordination

Tapping or clapping to an auditory beat, an easy task for most individuals, reveals precise temporal synchronization with auditory patterns such as music, even in the presence of temporal fluctuations. Most models of beat-tracking rely on the theoretical concept of pulse: a perceived regular beat generated by an internal oscillation that forms the foundation of entrainment abilities. Although tapping to the beat is a natural sensorimotor activity for most individuals, not everyone can track an auditory beat. Recently, the case of Mathieu was documented (Phillips-Silver et al. 2011 Neuropsychologia 49, 961–969. (doi:10.1016/j.neuropsychologia.2011.02.002)). Mathieu presented himself as having difficulty following a beat and exhibited synchronization failures. We examined beat-tracking in normal control participants, Mathieu, and a second beat-deaf individual, who tapped with an auditory metronome in which unpredictable perturbations were introduced to disrupt entrainment. Both beat-deaf cases exhibited failures in error correction in response to the perturbation task while exhibiting normal spontaneous motor tempi (in the absence of an auditory stimulus), supporting a deficit specific to perception–action coupling. A damped harmonic oscillator model was applied to the temporal adaptation responses; the model''s parameters of relaxation time and endogenous frequency accounted for differences between the beat-deaf cases as well as the control group individuals.     

睫状神经营养因子对NO引起海马神经元毒性反应的影响

本研究采用原代培养大鼠海马神经元,观察睫状神经营养因子（ｃｉｌｉａｒｙ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ,ＣＮＴＦ）对ＮＯ引起细胞毒性反应的影响。ＮＯ供体硝普钠与Ｓ－亚硝基－乙酰青霉胺,ＮＯＳ底物Ｌ－Ａｒｇ及钙载体ｉｏｎｏｍｙｃｉｎ,均可引起海马神经元存活率下降,ＬＤＨ漏出增加;提前２４ｈ给予不同浓度ＣＮＴＦ,均能提高神经元的存活率,减少ＬＤＨ漏出,其作用呈剂量依赖性。     

Hyperactivation of monkey spermatozoa is triggered by Ca2+ and completed by cAMP

Digital image analysis of the flagellar movements of cynomolgus macaque spermatozoa hyperactivated by caffeine and cAMP was carried out to understand the change in flagellar movements during hyperactivation. The degree of flagellar bending increased remarkably after hyperactivation, especially at the base of the midpiece. Mainly two beating patterns were seen in the hyperactivated monkey sperm flagella: remarkably asymmetrical flagellar bends of large amplitude and relatively symmetrical flagellar bends of large amplitude. The asymmetrical bends were often seen in the early stage of hyperactivation, whereas the symmetrical bends executed nonprogressive, figure-of-eight movement. Beat frequency of the hyperactivated spermatozoa significantly decreased while wavelength of flagellar waves roughly doubled. To determine the conditions under which the axonemes of hyperactivated sperm flagella have asymmetrical or symmetrical bends, the plasma membranes of monkey spermatozoa were extracted with Triton X-100 and motility was reactivated with MgATP(2-) under various conditions. The asymmetrical flagellar bends were brought about by Ca(2+), whereas the symmetrical flagellar bends resulted from low levels of Ca(2+) and high levels of cAMP. Under these conditions, beat frequency and wavelength of flagellar waves of demembranated, reactivated spermatozoa were similar to those of the hyperactivated spermatozoa. These results suggest that during hyperactivation of monkey spermatozoa intracellular Ca(2+) concentrations first rise, and then decrease while cAMP concentrations increase simultaneously.     

Identification and detection of the isolated sinus venosus from the Asian toad

The pacemaker activity of mammalian sinoatrial node (SAN) of the heart plays a fundamental role in the integration of vital functions. Studying factors such as drugs that influence pacemaker activity of SAN has its significance. In this study, we isolated sinus venosus, SAN from toads (Bufo gargarizans), and analysed its electronic signal, histological characteristics and the influence of acetylcholine (ACh) and ivabradine on its pacemaker activity using PowerLab® and Chart® 5.0 software. We found that when isolated sinus venosus was treated with ACh, its histological distribution was disorganized and inter‐beat (RR) interval was also broadened. The high frequency normalized unit (HFnu) and Poincaré plot of heart rate variability (HRV) of the isolated sinus venosus was also altered upon ACh treatment in a time‐dependent and dose‐dependent manner. When treated with ivabradine, these parameters of HRV such as square root of the mean of the squared differences between adjacent NN intervals (RMSSD) and HFnu were in the upward tendency, but low frequency normalized unit and low frequency/high frequency were in the opposite tendency. Taken together, we have developed a new model for studying the influences of drugs on autorhythmicity using isolated sinus venosus of the toad. With this model, we showed that ACh and ivabradine may affect the pacemaker activity by stimulating muscarinic receptor or inhibiting I_f current, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

An Ultrastructural Investigation of 180°-Rotated Ciliary Meridians in Tetrahymena pyriformis*

SYNOPSIS. An ultrastructural investigation has been carried out on 180°-rotated ciliary meridians (inverted meridians) in Tetrahymena pyriformis temperature-sensitive mutant (mol^b/mol^b), syngen 1, strain B. The longitudinal, transverse and postciliary microtubular bands, the kinetodesmal fiber, and the parasomal sac, are shown to be disposed at a 180° angle to their normal positions or orientations. Other abnormalities are as folows: the first 2 basal bodies of the inverted meridian fail to organize into “couplets” and the inverted meridian intrudes into the anterior pole region; an extra longitudinal microtubular band is found in one of the cell lines.     

Correlation between inhibition of calcium—dependent apoptosis by cyclosporin A and calcium transportation in HL—60 cells

Both calcium ionophore A23187 and endoplasmic reticulum Ca^2 -ATPase inhibitor thapsigargin (Tg) could increse intracellular free calcium concentration and induce apoptosis in some cell lines.In the present study,we found that HL-60 cells treated with A23187 (1μg/ml) for 4h or with Tg(0.5μg/ml) for 2h showed typical characteristics of apoptosis.Pretreatment with nontoxic concentration of cyclosporin A (CsA) (1μg/ml) could block these effects.Flow cytometric analysis of intracellular Ca^2 after staining with fluo-3 AM showed that CsA did not prevent the increase of intracellular calcium induced by A23187 or Tg,but it could maintain the high level of intracellular Ca^2 for a long time.These results suggest that CsA may prevent calcium-induced apoptosis by blocking the transportation of Ca^2 in HL-60 cells.     

Regulation of superoxide flashes by transient and steady mitochondrial calcium elevations

The mitochondria play essential roles in both intracellular calcium and reactive oxygen species signaling.As a newly discovered universal and fundamental mitochondrial phenomenon,superoxide flashes reflect transient bursts of superoxide production in the matrix of single mitochondria.Whether and how the superoxide flash activity is regulated by mitochondrial calcium remain largely unknown.Here we demonstrate that elevating mitochondrial calcium either by the calcium ionophore ionomycin or by increasing the bathing calcium in permeabilized HeLa cells increases superoxide flash incidence,and inhibition of the mitochondrial calcium uniporter activity abolishes the flash response.Quantitatively,the superoxide flash incidence is correlated to the steady-state mitochondrial calcium elevation with 1.7-fold increase per 1.0?F/F0 of Rhod-2 signal.In contrast,large mitochondrial calcium transients(e.g.,peak△F/F0~2.8,duration~2 min)in the absence of steady-state elevations failed to alter the flash activity.These results indicate that physiological levels of sustained,but not transient,mitochondrial calcium elevation acts as a potent regulator of superoxide flashes,but its mechanism of action likely involves a multi-step,slow-onset process.     

ABA-based chemical signalling: the co-ordination of responses to stress in plants

There is now strong evidence that the plant hormone abscisic acid (ABA) plays an important role in the regulation of stomatal behaviour and gas exchange of droughted plants. This regulation involves both long-distance transport and modulation of ABA concentration at the guard cells, as well as differential responses of the guard cells to a given dose of the hormone. We will describe how a plant can use the ABA signalling mechanism and other chemical signals to adjust the amount of water that it loses through its stomata in response to changes in both the rhizospheric and the aerial environment. The following components of the signalling process can play an important part in regulation: (a) ABA sequestration in the root; (b) ABA synthesis versus catabolism in the root; (c) the efficiency of ABA transfer across the root and into the xylem; (d) the exchange of ABA between the xylem lumen and the xylem parenchyma in the shoot; (e) the amount of ABA in the leaf symplastic reservoir and the efficiency of ABA sequestration and release from this compartment as regulated by factors such as root and leaf-sourced changes in pH; (f) cleavage of ABA from ABA conjugates in the leaf apoplast; (g) transfer of ABA from the leaf into the phloem; (h) the sensitivity of the guard cells to the [ABA] that finally reaches them; and lastly (i) the possible interaction between nitrate stress and the ABA signal.     

Effects of Activation of NMDA and AMPA Glutamate Receptors on the Extracellular Concentrations of Dopamine, Acetylcholine, and GABA in Striatum of the Awake Rat: A Microdialysis Study

The effects of activation of the AMPA and NMDA ionotropic glutamate receptors on the extracellular concentration of dopamine, acetylcholine, (ACh) and GABA in striatum of the awake rat was investigated. Also the levels of DOPAC, HVA, and choline (Ch) were included in this study. Seven to eight days after stereotaxical implantation of a guide-cannulae assembly, microdialysis experiments were performed. The dopamine and ACh content of samples were measured by HPLC coupled to electrochemical detection. GABA was measured using fluorometric detection. Perfusion of AMPA (1, 20, 100 mM) produced a dose-related increase of dopamine and a dose-related decrease of DOPAC and HVA. AMPA 100 M decreased extracellular concentrations of ACh and increased the extracellular concentration of Ch and GABA. Perfusion of NMDA 500 M increased the concentration of dopamine and decreased DOPAC and HVA. Also, NMDA 100 M decreased DOPAC. NMDA 500 M decreased the extracellular concentrations of ACh and increased the concentrations of Ch and GABA. Perfusion of the AMPA/kainate-antagonist DNQX (100 M) blocked the effects of AMPA (100 M) on dopamine, DOPAC, HVA, ACh, and GABA concentrations. Perfusion of the NMDA-antagonist CPP (100 M) blocked the effects of NMDA 500 M on dopamine, DOPAC, HVA, ACh, Ch, and GABA concentrations. These results suggest an interaction between glutamate-dopamine-ACh-GABA in striatum of the awake rat.     

Neuronal calcium signaling via store-operated channels in health and disease

Store-operated calcium entry (SOCE) is the flow of calcium ions (Ca²⁺) into cells in response to the depletion of intracellular Ca²⁺ stores that reside predominantly in the endoplasmic reticulum (ER). The role of SOCE has been relatively well understood for non-excitable cells. It is mediated mostly by the ER Ca²⁺ sensor STIM1 and plasma membrane Ca²⁺ channel Orai1 and serves to sustain Ca²⁺ signaling and refill ER Ca²⁺ stores. In contrast, because of the complexity of Ca²⁺ influx mechanisms that are present in excitable cells, our knowledge about the function of neuronal SOCE (nSOCE) is still nascent. This review summarizes the available data on the molecular components of nSOCE and their relevance to neuronal signaling. We also present evidence of disturbances of nSOCE in neurodegenerative diseases (namely Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease) and traumatic brain injury. The emerging important role of nSOCE in neuronal physiology and pathology makes it a possible clinical target.     

苹果多酚通过下调钙敏感受体改善大鼠低氧性肺动脉高压的作用

目的：探究苹果多酚通过下调钙敏感受体（CaSR）表达改善大鼠低氧性肺动脉高压的作用。方法：36只雄性SD大鼠随机分为对照组、低氧诱导组和苹果多酚干预组（n=12）。低氧诱导组和苹果多酚干预组大鼠每天在低氧舱（氧浓度为10%）中间断低氧暴露8 h,对照组在正常环境下饲养,为期四周。建模同时,苹果多酚干预组每日用苹果多酚按200 mg/kg的剂量灌胃,对照组、低氧诱导组用等量生理盐水灌胃,每日1次,共持续四周。建模完成后,检测各组大鼠的肺动脉平均压（mPAP）、肺血管阻力（PVR）、右心室肥厚指数（RVHI）、肺动脉中膜厚度（MT）、WA%、WT%及肺动脉组织中CaSR表达量。结果：低氧暴露组大鼠mPAP、PVR、RVHI、MT、WA%、WT%及肺动脉组织中CaSR表达量均较对照组明显升高（P<0.01）;苹果多酚干预组可改善上述效应。结论：苹果多酚能有效预防大鼠低氧性肺动脉高压,其机制与下调CaSR的表达有关。     

Ubiquilin 1 interacts with Orai1 to regulate calcium mobilization

Store-operated calcium entry (SOCE) channels composed of Stim and Orai proteins play a critical role in diverse biological processes. Upon endoplasmic reticulum (ER)-mediated calcium (Ca²⁺) depletion, Stim proteins oligomerize with Orai to initiate Ca²⁺ influx across the plasma membrane. The ubiquitin-like (UBL) and ubiquitin-associated (UBA) domains of ubiquilin 1 are involved in the degradation of presenilin and polyglutamine proteins. Through screening of Orai1 interaction partner(s) that might have an effect on SOCE, ubiquilin 1 was identified as a target of Orai1. However, the UBL and UBA domains of ubiquilin 1 were dispensable for this interaction. Additionally, ubiquilin 1 and Orai1 colocalized in the cytosolic compartment. Ubiquilin 1 increased the ubiquitination of Orai1, resulting in the formation of a high-molecular-weight form. MG132, a proteasome inhibitor, failed to block the degradation of Orai1, whereas bafilomycin A, a lysosome inhibitor, prevented Orai1 degradation. Confocal microscopy studies demonstrated that a fraction of Orai1 colocalized with ubiquilin 1 and the autophagosomal marker LC3. Because Orai1 is a constituent of SOCE, we determined the effect of ubiquilin 1 on Orai1-mediated Ca²⁺ influx. As we expected, intracellular Ca²⁺ mobilization, a process normally potentiated by Orai1, was downregulated by ubiquilin 1. Taken together, these findings suggest that ubiquilin 1 downregulates intracellular Ca²⁺ mobilization and its downstream signaling by promoting the ubiquitination and lysosomal degradation of Orai1.