scholarly journals Calcium control of ciliary reversal in ionophore-treated and ATP-reactivated comb plates of ctenophores.

1985 ◽  
Vol 100 (5) ◽  
pp. 1447-1454 ◽  
Author(s):  
S Nakamura ◽  
S L Tamm
Keyword(s):  
Beat Frequency ◽  
Reverse Direction ◽  
Ionophore A23187 ◽  
Free Medium ◽  
Nervous Control ◽  
Future Studies ◽  
Ciliary Motion ◽  
Ciliary Reversal ◽  
Ion Substitution ◽  
Reversal Mechanism

Previous work showed that ctenophore larvae swim backwards in high-KCl seawater, due to a 180 degrees reversal in the direction of effective stroke of their ciliary comb plates (Tamm, S. L., and S. Tamm, 1981, J. Cell Biol., 89: 495-509). Ion substitution and blocking experiments indicated that this response is Ca2+ dependent, but comb plate cells are innervated and presumably under nervous control. To determine whether Ca2+ is directly involved in activating the ciliary reversal mechanism and/or is required for synaptic triggering of the response, we (a) determined the effects of ionophore A23187 and Ca2+ on the beat direction of isolated nerve-free comb plates dissociated from larvae by hypotonic, divalent cation-free medium, and (b) used permeabilized ATP-reactivated models of comb plates to test motile responses to known concentrations of free Ca2+. We found that 5 microM A23187 and 10 mM Ca2+ induced dissociated comb plate cells to beat in the reverse direction and to swim counterclockwise in circular paths instead of in the normal clockwise direction. Detergent/glycerol-extracted comb plates beat actively in the presence of ATP, and reactivation was reversibly inhibited by micromolar concentrations of vanadate. Free Ca2+ concentrations greater than 10(-6)M caused reversal in direction of the effective stroke but no significant increase in beat frequency. These results show that ciliary reversal in ctenophores, like that in protozoa, is activated by an increase in intracellular free Ca2+ ions. This allows the unique experimental advantages of ctenophore comb plate cilia to be used for future studies on the site and mechanism of action of Ca2+ in the regulation of ciliary motion.

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.

scholarly journals Calcium metabolism in rat hepatocytes

1978 ◽  
Vol 170 (3) ◽  
pp. 615-625 ◽  
Author(s):  
S Foden ◽  
P J Randle
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Rat Hepatocytes ◽  
Ionophore A23187 ◽  
Total Calcium ◽  
Free Medium ◽  
Adrenergic Agonists ◽  
Calcium Efflux ◽  
Similar Time ◽  
Carbonyl Cyanide

1. The total calcium concentration in rat hepatocytes was 7.9 microgram-atoms/g dry wt.; 77% of this was mitochondrial. Approx. 20% of cell calcium exchanged with 45Ca within 2 min. Thereafter incorporation proceeded at a low rate to reach 28% of total calcium after 60 min. Incorporation into mitochondria showed a similar time course and accounted for 20% of mitochondrial total calcium after 60 min. 2. The alpha-adrenergic agonists phenylephrine and adrenaline + propranolol stimulated incorporation of 45Ca into hepatocytes. Phenylephrine was shown to increase total calcium in hepatocytes. Phenylephrine inhibited efflux fo 45Ca from hepatocytes perifused with calcium-free medium. 3. Glucagon, dibutryl cyclic AMP and beta-adrenergic agonists adrenaline and 3-isobutyl-1-methyl-xanthine stimulated calcium efflux from hepatocytes perifused with calcium-free medium. The effect of glucagon was blocked by insulin. Insulin itself had no effect on calcium efflux and it did not affect the response to dibutyryl cyclic AMP. 4. Incorporation of 45Ca into mitochondria in hepatocytes was stimulated by phenylephrine and inhibited by glucagon and by carbonyl cyanide p-trifluoromethoxyphenylhydrazone. The effect of glucagon was blocked by insulin. 5. Ionophore A23187 stimulated hepatocyte uptake of 45Ca, uptake of 45Ca into mitochondria in hepatocytes and efflux of 45Ca into a calcium-free medium.

Unilateral ciliary reversal and motor responses during prey capture by the ctenophore Pleurobrachia

1985 ◽  
Vol 114 (1) ◽  
pp. 443-461 ◽  
Author(s):  
S. L. Tamm ◽  
A. G. Moss
Keyword(s):  
High Frequency ◽  
Feeding Behaviour ◽  
High Speed ◽  
Prey Capture ◽  
Reverse Direction ◽  
Motor Responses ◽  
Ciliary Reversal ◽  
High Speed Cinematography

High-speed cinematography of feeding Pleurobrachia revealed a stereo-typed sequence of ciliary motor responses underlying the feeding behaviour of this ctenophore. Prey capture by a tentacle first elicited high frequency beating in all comb rows, propelling the animal forward at a rapid speed for several seconds. This was followed by a brief period of inactivity on some or all comb rows. Then comb rows adjacent to the catching tentacle beat in the reverse direction, causing the ctenophore to spin rapidly toward this side and sweeping the prey-catching tentacle to the opened mouth, which bent towards it. After engulfing the prey, the animal slowly swam forward to re-set the relaxed tentacles as a fishing net. The patterns, timing, onset and coordination of these ciliary responses, particularly the unilateral reversal of comb rows on the catching side, are analysed with respect to possible conducting pathways mediating this behaviour.

Effect of the ionophore A23187 on chloride transport across isolated frog cornea

1977 ◽  
Vol 233 (2) ◽  
pp. F94-F101
Author(s):  
O. A. Candia ◽  
R. Montoreano ◽  
S. M. Podos
Keyword(s):  
Chloride Transport ◽  
Ringer Solution ◽  
Ionophore A23187 ◽  
Free Medium ◽  
Intracellular Ca ◽  
Adrenergic Blockers ◽  
Relative Inhibition ◽  
Stimulation Of ◽  
Frog Cornea ◽  
Cl Permeability

The ionophore A23187 at a concentration of 10(-7) to 10(-5) M stimulated active transport of Cl across the isolated frog cornea. The ionophore had no effect in a Cl-free medium. Both unidirectional Cl fluxes were increased by A23187. The electrical resistance was decreased, and this can be totally accounted for by the increment in passive Cl fluxes. The effect of A23187 on Cl transport and permeability mimicked the effects of cyclic AMP, isoproterenol, and epinephrine. A23187 had no effect when the corneas were fully stimulated by epinephrine or isoproterenol. A23187 produced normal stimulation of the SCC in corneas pretreated with alpha- and beta-adrenergic blockers. The stimulation of the SCC by A23187 was dependent on the presence of Ca in the Ringer solution. Excess Ca (10 mM) resulted in a reduced response. Increasing the Mg concentration in the medium reduced the stimulation of the SCC with Ca concentrations of 0.1-5 mM, but prevented the relative inhibition of 10 mM Ca. Intracellular Ca concentration seemed to regulate Cl permeability of the cornea.

Manipulating external Ca2+ inhibits particle capture by planktotrophic echinoderm larvae

1990 ◽  
Vol 68 (12) ◽  
pp. 2610-2615 ◽  
Author(s):  
Michael W. Hart
Keyword(s):  
Calcium Ion ◽  
Channel Blocker ◽  
Artificial Seawater ◽  
Ciliated Cells ◽  
Particle Capture ◽  
Concentrated Solutions ◽  
Ciliary Reversal ◽  
Reversal Mechanism ◽  
Planktotrophic Larvae ◽  
Ciliary Beat

Planktotrophic larvae of echinoderms feed by filtering suspended particles from seawater using a ciliary reversal mechanism. The control of ciliary beat depends on calcium ion flux across the membranes of ciliated cells in many organisms. In an earlier study, T. H. J. Gilmour (1985. Can. J. Zool. 63: 1354–1359) observed that the calcium channel blocker verapamil failed to prevent particle capture by echinoid larvae, and he interpreted this result as indicating that ciliary reversals are not important in particle capture by these larvae. I have also found that echinoid and asteroid larvae feed normally (and have high rates of clearance) in concentrated solutions of verapamil in seawater, but particle captures by these larvae are qualitatively identical to those by the same larvae before exposure to verapamil and they appear to occur by ciliary reversal. Clearance rates are greatly depressed, however, for larvae in Ca2+-free artificial seawater and for larvae in artificial seawater containing 9 mM Co2+. Most particle captures under these conditions do not appear to occur by the reversal of ciliary beat. These observations suggest that verapamil fails to block calcium channels in the membranes of ciliated cells of echinoderm larvae, but that other methods of preventing transmembrane Ca2+ flux do interfere with ciliary reversals and particle capture.

scholarly journals The role of neutrophil membrane glycoprotein GP-150 in neutrophil adherence to endothelium in vitro

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 167-178 ◽  
Author(s):  
JM Harlan ◽  
PD Killen ◽  
FM Senecal ◽  
BR Schwartz ◽  
EK Yee ◽  
...  
Keyword(s):  
Calcium Ionophore ◽  
Membrane Glycoprotein ◽  
Ionophore A23187 ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Endothelial Monolayers ◽  
Neutrophil Adherence

Abstract We have previously described two patients with a congenital defect in neutrophil function characterized by an inability to form pus. The patients' neutrophils lack a membrane glycoprotein of mol wt 150,000 daltons (GP-150) on analysis by SDS-PAGE. This glycoprotein is part of a membrane antigen complex recognized by the murine monoclonal antibody (MoAb) 60.3. Addition of MoAb 60.3 to normal neutrophils produces defects in chemotaxis and phagocytosis in vitro similar to those observed in the patients. Since neutrophil adherence to vascular endothelium is prerequisite to neutrophil emigration in vivo, we examined the interaction of the patients' neutrophils and normal neutrophils treated with MoAb 60.3 with cultured endothelium. Adherence was determined as the percentage of 51Cr-labeled purified peripheral blood neutrophils which remained adherent to plastic wells or endothelial monolayers after a 45-minute incubation at 37 degrees C. The percentage of neutrophils from patient 1 remaining adherent to uncoated, fibronectin-coated, or laminin-coated plastic was similar to that observed in normal neutrophils (55% to 84% adherence with normal neutrophils v 73% to 78% adherence with the patient's neutrophils and 63% to 82% adherence with MoAb 60.3-treated normal neutrophils). The adherence of the neutrophils from patient 1 and MoAb 60.3-treated normal neutrophils to human or bovine endothelium in serum-free medium was also not significantly different from that observed in normal neutrophils (less than 10% adherence with normal, MoAb 60.3-treated, and patient neutrophils). In medium containing 10% autologous or heterologous human plasma, however, the adherence of neutrophils from patient 1 or MoAb 60.3-treated normal neutrophils to endothelial monolayers was significantly reduced (35% +/- 7% of normal neutrophils in seven experiments). Although phorbol myristate acetate (PMA) (10 ng/mL) and calcium ionophore A23187 (10(-5) mol/L) markedly increased the adherence of normal neutrophils to endothelial monolayers in serum- free medium (40% to 85% adherence), neither agent increased the adherence of the neutrophils from patient 1 or normal neutrophils treated with MoAb 60.3 (less than 5% adherence). The adherence of PMA- activated neutrophils from patient 2 to endothelial monolayers was also markedly decreased when compared with that of normal neutrophils. Postsecretory cell-free supernatants from PMA-activated normal neutrophils failed to augment adherence of neutrophils from patient 1 (less than 5% adherence).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals The dissociation of exocytosis and respiratory stimulation in leucocytes by ionophores

1976 ◽  
Vol 156 (2) ◽  
pp. 209-213 ◽  
Author(s):  
G Zabucchi ◽  
D Romeo
Keyword(s):  
Oxygen Consumption ◽  
Lactate Dehydrogenase ◽  
Ionophore A23187 ◽  
Polymorphonuclear Leucocytes ◽  
Free Medium ◽  
Alkali Cations ◽  
Experimental Conditions ◽  
Bivalent Cations ◽  
Respiratory Stimulation ◽  
Stimulation Of

By exploiting the unique characteristics of three ionophores, experimental conditions were found which permit the dissociation of respiratory stimulation from secretion in polymorphonuclear leucocytes. A marked stimulation of respiration was produced by ionophore X537A, which binds and transports both alkali-earth and alkali cations. The stimulatory activity of this ionophore was the same at either high or low Na+/K+ ratios in the medium and was virtually unaffected by extracellular Ca2+. A slight stimulation of oxygen consumption was also caused by the K+-selective ionophore valinomycin and by ionophore A23187, which complexes and transfers bivalent cations. Ionophore X537A and valinomycin were unable to stimulate selective release of granuleassociated β-glucuronidase and gradually increased cell fragility, as monitored by increased leakage of lactate dehydrogenase. Ionophore A23187 slightly increased exocytosis of β-glucuronidase. In a Mg2+-free medium, Ca2+, added simultaneously with ionophore A23187, greatly enhanced respiration and secretion of the granule enzyme. If Ca2+ was added a few minutes after the ionophore, exocytosis occurred, but no respiratory burst was observed. If the latter experiment was repeated in the presence of extracellular Mg2+, both secretion and respiration were stimulated. This effect was not produced by Mn2+ or Ba2+. It is proposed that Ca2+ is required for triggering selective secretion of granule enzymes from leucocytes is caused by an intracellular redistribution of cations, which may invovle Mg2+-dependent mechanisms.

scholarly journals In vivo and in vitro observation of nasal ciliary motion in a guinea pig model

2020 ◽  
Vol 245 (12) ◽  
pp. 1039-1048
Author(s):  
Chuan Pang ◽  
Fengwei An ◽  
Shiming Yang ◽  
Ning Yu ◽  
Daishi Chen ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Physiological Function ◽  
Beat Frequency ◽  
Ciliary Function ◽  
Ciliary Motion ◽  
Response To Temperature ◽  
Over Time ◽  
Ciliary Beat

In vitro airway specimens are widely used to evaluate airway ciliary function. However, the function of in vitro ciliated cells may be far different from their actual in vivo physiological conditions. Due to the lack of a valid technique, direct images of in vivo airway ciliary motion have never been captured and analyzed before. This study aims to examine nasal ciliary motion in living guinea pigs with comparison to in vitro observation. Nasal septum mucosa was exposed in anaesthetized guinea pigs and directly examined using a digital microscopy system. The study included three parts: (1) measurement of ciliary beat frequency (CBF) of nasal mucosa at room temperature in living guinea pigs and immediately after death, and in dissected mucosa specimens/cells for comparison; (2) monitoring of nasal ciliary motion, CBF, and ciliary beat distance (CBD) over 12 h in both living guinea pigs and dissected mucosa specimens/cells; and (3) measurement of ciliary motion changes in responses to temperature variations. Compared with when the animal was alive, the CBF after death and in dissected mucosa specimens/cells was lower by about 20% ( P < 0.05). CBF and CBD variation in living guinea pigs was within 10% over time. The slope of CBF/temperature profile was 0.18 ± 0.01 Hz/°C in living guinea pigs, 0.51 ± 0.02 Hz/°C for dissected mucosa specimens, and 0.48 ± 0.03 Hz/°C for isolated ciliary cells. The technique described in this study makes it feasible to study ciliary motion in living animals using the digital microscope system. Ciliary function changes immediately after death. Ciliary motion in a living animal is more stable over time and has a different response to temperature change as compared with in vitro observation results. Impact statement Cilia play an important role in the airway defense mechanism. So far, studies on ciliary function have mainly been based on in vitro methods. Images of in vivo ciliary motion are very difficult to capture. In this study, we describe a novel approach to observe and analyze nasal ciliary motion in living animals with comparison to in vitro observation. Such images of ciliary motion from living animals have not been reported to date. The result of the study indicates that in vivo ciliary physiological function differs from ex vivo and in vitro conditions in many ways, such as the stability over time and response to temperature variation. This is a good foundation for further in vivo analysis of airway ciliary physiological function in animals as well as humans.

scholarly journals Prey capture analyses in the carnivorous aquatic waterwheel plant (Aldrovanda vesiculosa L., Droseraceae)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Simon Poppinga ◽  
Jassir Smaij ◽  
Anna Sofia Westermeier ◽  
Martin Horstmann ◽  
Sebastian Kruppert ◽  
...  
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Beat Frequency ◽  
Capture Rate ◽  
Water Flea ◽  
Predator Prey ◽  
Future Studies ◽  
Starting Position ◽  
High Speed Cinematography ◽  
Movement Type

AbstractWe investigated the predator-prey interactions between an Australian ecotype of the carnivorous waterwheel plant (Aldrovanda vesiculosa, Droseraceae) and its potential natural prey, the water flea Daphnia longicephala (Daphniidae), which also occurs in Australia. A. vesiculosa develops snap-traps, which close within ~10–100 ms after mechanical triggering by zooplankton prey. Prey capture attempts (PCAs) were recorded via high-speed cinematography in the laboratory. From 14 recorded PCAs, nine were successful for the plant (the prey was caught), and five were unsuccessful (prey could escape), resulting in a capture rate of ~64%. The prey animals’ locomotion behaviour (antenna beat frequency and movement type) in trap vicinity or inside the open traps is very variable. Traps were mainly triggered with the second antennae. During trap closure, the animals moved only very little actively. A flight response in reaction to an initiated trap closure was not observed. However, several animals could escape, either by having a “lucky” starting position already outside the triggered trap, by freeing themselves after trap closure, or by being pressed out by the closing trap lobes. According to our observations in the successful PCAs, we hypothesize that the convex curvature of the two trap lobes (as seen from the outside) and the infolded trap rims are structural means supporting the capture and retention of prey. Our results are discussed in a broader biological context and promising aspects for future studies are proposed.

scholarly journals Calcium metabolism and amylase release in rat parotid acinar cells

1976 ◽  
Vol 160 (3) ◽  
pp. 547-564 ◽  
Author(s):  
P Kanagasuntheram ◽  
P J Randle
Keyword(s):  
Cyclic Amp ◽  
Molecular Mechanisms ◽  
Acinar Cells ◽  
Ionophore A23187 ◽  
Free Medium ◽  
Dibutyryl Cyclic Amp ◽  
Trypan Blue Exclusion ◽  
Amylase Release ◽  
Parotid Acinar Cells ◽  
Rat Parotid

1. A method is described for the isolation of rat parotid acinar cells by controlled digestion of the gland with trypsin followed by collagenase. As judged by Trypan Blue exclusion, electron microscopy, water, electrolyte and ATP concentrations and release of amylase and lactate dehydrogenase, the cells are morphologically and functionally intact. 2. A method was developed for perifusion of acinar cells by embedding them in Sephadex G-10. Release of amylase was stimulated by adrenaline (0.1-10μM), isoproternol (1 or 10 μM), phenylephrine (1 μM), carbamoylcholine (0.1 or 1 μM), dibutyryl cycle AMP (2 MM), 3-isobutyl-1-methylxanthine (1mM) and ionophore A23187. The effects of phenylephrine, carbamoylcholine and ionophore A23187 required extracellular Ca2+, whereas the effects of adrenaline and isoproterenol did not. 3. The incorporation of 45Ca into parotid cells showed a rapidly equilibrating pool (1-2 min) corresponding to 15% of total Ca2+ and a slowly equilibrating pool (> 3h) of probably a similar dimension. Cholinergic and α-adrenergic effectors and ionophore A23187 and 2,4-dinitrophenol increased the rate of incorporation of 45Ca into a slowly equilibrating pool, whereas β-adrenergic effectors and dibutyryl cyclic AMP were inactive. 4. The efflux of 45Ca from cells into Ca2+-free medium was inhibited by phenylephrine and carbamoylcholine and accelerated by isoproterenol, adrenaline (β-adrenergic effect), dibutyryl cyclic AMP and ionophore A23187. 5. A method was developed for the measurement of exchangeable 45Ca in mitochondria in parotid pieces. Incorporation of 45Ca into mitochondria was decreased by isoproterenol, dibutyryl cyclic AMP or 2,4-dinitrophenol, increased by adrenaline, and not changed significantly by phenylephrine or carbamoylcholine. Release of 45Ca from mitochondria in parotid pieced incubated in a Ca2+-free medium was increased by isoproterenol, adrenaline, dibutyryl cyclic AMP or 2,4-dinitrophenol and unaffected by phenylephrine or carbamoylcholine. 6. These findings are compatible with a role for Ca2+ as a mediator of amylase-secretory responses in rat parotid acinar cells, but no definite conclusions about its role can be drawn in the absence of knowledge of the molecular mechanisms involved, their location, and free Ca2+ concentration in appropriate cell compartment(s).

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