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Abstract
The procedure for the fabrication of a detector termed NACAD, nanofabricated carbon-based detector, is described. I characterized the mechanical properties of this detector using atomic force and scanning electron microscopy techniques. This detector exhibits a smooth surface (rms 2-4 nm) and easy access for atomic force microscopy tips, necessary features for biological studies of secretory granules and vesicles, which store transmitters and release them via exocytosis. The NACAD does not impair the elastic properties of granular matrixes deposited onto a detector, as they show their typical Young's moduli and ion exchanger properties; divalent histamine shrinks them, while monovalent sodium causes their swelling. Additionally, the NACADs' electrochemical properties allowed amperometric measurements of serotonin released from intact secretory granules isolated from mast cells, after removal of their granular membranes using a mild detergent treatment. Thus, this detector will aid future studies of single secretory granules and vesicles and their insoluble matrixes.
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Affiliation(s)
- Vladimir Parpura
- Department of Cell Biology and Neuroscience and Center for Nanoscale Science and Engineering, University of California, Riverside, California 92521, USA.
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2
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Stenholm A, Lindgren H, Shaffie J. Comparison of amine-selective properties of weak and strong cation-exchangers. J Chromatogr A 2006; 1128:73-8. [PMID: 16820152 DOI: 10.1016/j.chroma.2006.06.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 06/07/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
The capacity of several weak and strong cation-exchangers to adsorb 2-diethylaminoethanol (DEAE) and (2,3-hydroxypropyl) trimethylammonium chloride (HPMAC) from sodium-containing process water streams, and the ease of subsequently eluting the amines and regenerating the exchangers, were investigated. (2,3-hydroxypropyl) trimethylammonium chloride was enriched 40-fold compared with the initial amine/sodium-ratio in the bulk fluid by Amberlite IRC-50. The highest selectivity for 2-diethylaminoethanol (26-fold) was provided by Imac HP336. Neither of the selected strong cation-exchangers showed any selectivity towards 2-diethylaminoethanol, but they enriched (2,3-hydroxypropyl) trimethylammonium chloride approximately three to four fold. These findings suggest that weak cation-exchangers (WCX) could be readily used for the selective removal of these or similar amines from sodium-containing process waters.
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Affiliation(s)
- Ake Stenholm
- Product Supply, GE Healthcare, Protein Separations, Björkgatan 30, S-751 84 Uppsala, Sweden.
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3
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Marszalek PE, Oberhauser AF, Li H, Fernandez JM. The force-driven conformations of heparin studied with single molecule force microscopy. Biophys J 2004; 85:2696-704. [PMID: 14507732 PMCID: PMC1303493 DOI: 10.1016/s0006-3495(03)74692-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Using single molecule force spectroscopy we examine the response of heparin chains to mechanical stretching. We find that at forces below 200 pN heparin behaves as a simple entropic spring. At approximately 200 pN heparin displays a large enthalpic elasticity, which is evident as a pronounced plateau in the force-extension relationship. We determine that this enthalpic elasticity is produced by sugar rings of heparin flipping to more energetic and more extended conformations. We estimate that in vivo, the forces which stretch heparin are comparable to the forces that trigger conformational transitions in our single molecule atomic force microscopy measurements. We hypothesize that these conformational transitions have biological significance in that they provide a mechanism to finely regulate the affinity of various ligands toward heparin, for example, in secretory granules undergoing exocytosis and during the mechanical interactions between cells and the extracellular matrix.
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Affiliation(s)
- Piotr E Marszalek
- Department of Mechanical Engineering and Material Sciences, Duke University, Durham, North Carolina 27708 USA
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4
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Sombers LA, Hanchar HJ, Colliver TL, Wittenberg N, Cans A, Arbault S, Amatore C, Ewing AG. The effects of vesicular volume on secretion through the fusion pore in exocytotic release from PC12 cells. J Neurosci 2004; 24:303-9. [PMID: 14724228 PMCID: PMC6729980 DOI: 10.1523/jneurosci.1119-03.2004] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many spikes in amperometric records of exocytosis events initially exhibit a prespike feature, or foot, which represents a steady-state flux of neurotransmitter through a stable fusion pore spanning both the vesicle and plasma membranes and connecting the vesicle lumen to the extracellular fluid. Here, we present the first evidence indicating that vesicular volume before secretion is strongly correlated with the characteristics of amperometric foot events. L-3,4-dihydroxyphenylalanine and reserpine have been used to increase and decrease, respectively, the volume of single pheochromocytoma cell vesicles. Amperometry and transmission electron microscopy have been used to determine that as vesicle size is decreased the frequency with which foot events are observed increases, the amount and duration of neurotransmitter released in the foot portion of the event decreases, and vesicles release a greater percentage of their total contents in the foot portion of the event. This previously unidentified correlation provides new insight into how vesicle volume can modulate the activity of the exocytotic fusion pore.
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Affiliation(s)
- L A Sombers
- Department of Chemistry, 152 Davey Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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5
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Abstract
There is accumulating evidence that two aspects of the innate immune response, the respiratory burst and secretion of proteases, are intimately intertwined. A recent study suggests that K(+) may be the missing link. Is it time to merge signal transduction with biophysics?
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Affiliation(s)
- Rene E Harrison
- Cell Biology Programme, The Hospital for Sick Children Research Institute, 555 University Avenue, Ontario, M5G 1X8, Toronto, Canada
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Meir A, Ginsburg S, Butkevich A, Kachalsky SG, Kaiserman I, Ahdut R, Demirgoren S, Rahamimoff R. Ion channels in presynaptic nerve terminals and control of transmitter release. Physiol Rev 1999; 79:1019-88. [PMID: 10390521 DOI: 10.1152/physrev.1999.79.3.1019] [Citation(s) in RCA: 220] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The primary function of the presynaptic nerve terminal is to release transmitter quanta and thus activate the postsynaptic target cell. In almost every step leading to the release of transmitter quanta, there is a substantial involvement of ion channels. In this review, the multitude of ion channels in the presynaptic terminal are surveyed. There are at least 12 different major categories of ion channels representing several tens of different ion channel types; the number of different ion channel molecules at presynaptic nerve terminals is many hundreds. We describe the different ion channel molecules at the surface membrane and inside the nerve terminal in the context of their possible role in the process of transmitter release. Frequently, a number of different ion channel molecules, with the same basic function, are present at the same nerve terminal. This is especially evident in the cases of calcium channels and potassium channels. This abundance of ion channels allows for a physiological and pharmacological fine tuning of the process of transmitter release and thus of synaptic transmission.
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Affiliation(s)
- A Meir
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University Hadassah Medical School, Jerusalem, Israel
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7
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Rahamimoff R, Butkevich A, Duridanova D, Ahdut R, Harari E, Kachalsky SG. Multitude of ion channels in the regulation of transmitter release. Philos Trans R Soc Lond B Biol Sci 1999; 354:281-8. [PMID: 10212476 PMCID: PMC1692499 DOI: 10.1098/rstb.1999.0379] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The presynaptic nerve terminal is of key importance in communication in the nervous system. Its primary role is to release transmitter quanta on the arrival of an appropriate stimulus. The structural basis of these transmitter quanta are the synaptic vesicles that fuse with the surface membrane of the nerve terminal, to release their content of neurotransmitter molecules and other vesicular components. We subdivide the control of quantal release into two major classes: the processes that take place before the fusion of the synaptic vesicle with the surface membrane (the pre-fusion control) and the processes that occur after the fusion of the vesicle (the post-fusion control). The pre-fusion control is the main determinant of transmitter release. It is achieved by a wide variety of cellular components, among them the ion channels. There are reports of several hundred different ion channel molecules at the surface membrane of the nerve terminal, that for convenience can be grouped into eight major categories. They are the voltage-dependent calcium channels, the potassium channels, the calcium-gated potassium channels, the sodium channels, the chloride channels, the non-selective channels, the ligand gated channels and the stretch-activated channels. There are several categories of intracellular channels in the mitochondria, endoplasmic reticulum and the synaptic vesicles. We speculate that the vesicle channels may be of an importance in the post-fusion control of transmitter release.
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Affiliation(s)
- R Rahamimoff
- Department of Physiology, Hebrew University Hadassah Medical School, Jerusalem, Israel.
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8
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Abstract
Membrane traffic is an important aspect of cell biology which implies shuttle vesicles and multiple binding/fusion events. In spite of rapid progress at the biochemical level, the mechanism of fusion is still not understood. A detailed physical description of the phenomenon is possible at the level of the plasma membrane where secretory vesicles fuse with the cell membrane, a process known as exocytosis. This process is specially active in neurons (release of neurotransmitter) and in endocrine cells (release of hormones), where exocytosis is tightly regulated. Among the biophysical techniques developed, cell membrane capacitance measurements by the technique of patch-clamp and amperometry of the oxidizable secretory products have resulted in interesting information. These techniques have described the initial fusion pore, its fluctuations, the efflux of material through the pore and its irreversible expansion. Optical techniques, using bioluminescent and fluorescent probes are also in progress. For instance, the dye FM 1-43 binds to but is not translocated through biological membranes and it has been used to measure membrane surface, as done by capacitance measurement. Evanescent wave fluorescence microscopy has been recently introduced to analyse the behaviour of secretory granules in the vicinity of the plasma membrane.
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Castle D, Castle A. Intracellular transport and secretion of salivary proteins. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1998; 9:4-22. [PMID: 9488245 DOI: 10.1177/10454411980090010301] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Intracellular transport and secretion of salivary proteins are major activities of salivary acinar cells. While the major intracellular pathway followed by salivary proteins following their synthesis has been described previously, there is only limited understanding of how this process is regulated at the molecular level. Studies of salivary proteins, especially proline-rich proteins, expressed in an endocrine cell line have begun to provide insight regarding intermolecular interactions during transport and the role played by structural signals during intracellular sorting. Analysis of the secretion of newly synthesized salivary proteins in parotid tissue has shown that there are multiple pathways of discharge from acinar cells. While granule exocytosis is the major pathway, at least two other pathways that export salivary proteins have been found to originate from maturing secretion granules. These pathways may contribute to other acinar cell functions, including secretion of proteins in the absence of acute stimulation and support of the secretory process for fluid and electrolytes.
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Affiliation(s)
- D Castle
- Department of Cell Biology, University of Virginia Health Sciences Center, Charlottesville 22908, USA
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10
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Marszalek PE, Farrell B, Verdugo P, Fernandez JM. Kinetics of release of serotonin from isolated secretory granules. II. Ion exchange determines the diffusivity of serotonin. Biophys J 1997; 73:1169-83. [PMID: 9284284 PMCID: PMC1181016 DOI: 10.1016/s0006-3495(97)78149-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We measured the efflux of 5-hydroxytryptamine (5-HT, serotonin) from an intact secretory granule extracted from the mast cell of the beige mouse. The efflux was measured with amperometry after rupture of the granule membrane was triggered by electroporation. We determined the diffusivity of 5-HT within the secretory granule to be 2.0 x 10(-8) cm2 s(-1) when the granule is in contact with a physiological saline and found that this diffusivity depends on the valence of the cation in the external electrolyte. There is a fivefold increase in the diffusion coefficient of 5-HT determined in CsCl (150 mM, pH 7.2) at 3.7 x 10(-8) cm2 s(-1) compared to that determined in histamine dihydrochloride (Hi, 100 mM at pH 4.5) at 0.7 x 10(-8) cm2 s(-1). We found that the rate of expansion of the granule matrix observed in physiological medium correlates with the efflux of 5-HT, and that the rate of swelling of the matrix and the efflux depend on the microviscosity within the granule matrix and not the bulk viscosity of the external solution. The low diffusivity of 5-HT (approximately 500-fold less than in the bulk), the observation that the valence of the counterion affects this diffusivity, and the relationship between the volume changes of the matrix and the efflux suggest that 5-HT is released from the granule by ion exchange. We discuss the implications of this result for exocytotic release in mast cells and propose that an ion exchange mechanism could control the rate of release in other secretory systems.
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Affiliation(s)
- P E Marszalek
- Department of Physiology and Biophysics, Mayo Foundation, Rochester, Minnesota 55905, USA
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11
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Affiliation(s)
- R Rahamimoff
- Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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12
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Abstract
We have used an atomic force microscope to study the mechanical properties of the matrix found in the lumen of secretory granules isolated from mast cells. The matrices were insoluble and had an average height of 474 +/- 197 nm. The volume of these matrices increased reversibly about tenfold by decreasing the valency of the bathing external cation (La3+ < Ca2+ < Na+). The elastic (Young's) modulus was found to decrease by about 100-fold (4.3 MPa in La3+ to 37 kPa in Na+) upon a tenfold increase in the matrix volume. A swollen granule matrix had an elastic modulus similar to that of gelatin in water. The elastic modulus was inversely related to the change in the volume of the matrix, following a relationship similar to that predicted for the elasticity of weakly cross-linked polymers. Our results show that the matrix of these secretory granules have the mechanical properties of weak ion exchange resins, lending strong support to an ion exchange mechanism for the storage and release of cationic secretory products.
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Affiliation(s)
- V Parpura
- Mayo Foundation, Department of Physiology and Biophysics, Rochester, Minnesota 55905, USA
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13
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Affiliation(s)
- L J DeFelice
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600, USA
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14
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Abstract
Membrane fusion occurs as part of processes as different as synaptic neurotransmitter transmission and infection with influenza virus. Recent evidence paints a picture in which the organization of proteins into a macromolecular scaffold brings the two fusing membranes together and induces hemifusion, that is, the fusion of the apposing leaflets of the two membranes to form a common bilayer. A small dynamic fusion pore forms in the common bilayer and usually expands to allow complete membrane merging. The mechanisms of fusion appear to be remarkably similar in exocytosis and virus-induced fusion. During exocytotic fusion, there is an additional twist to the mechanism, as sometimes the fusion pores close after release of small non-quantal amounts of secretory products.
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Affiliation(s)
- J R Monck
- Department of Physiology, University of California at Los Angeles School of Medicine, 90024, USA.
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15
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Uvnäs B, Aborg CH. A mixed cation (IRC-50)-anion (IR-4B) exchanger shows storage properties reminiscent of the storage of catecholamines (CA) and adenosine triphosphate (ATP) in chromaffin granules. ACTA PHYSIOLOGICA SCANDINAVICA 1987; 129:587-8. [PMID: 3591382 DOI: 10.1111/j.1748-1716.1987.tb08101.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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16
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Uvnäs B, Aborg CH, Lyssarides L, Thyberg J. Cation exchanger properties of isolated rat peritoneal mast cell granules. ACTA PHYSIOLOGICA SCANDINAVICA 1985; 125:25-31. [PMID: 2413721 DOI: 10.1111/j.1748-1716.1985.tb07689.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The synthetic carboxylic cation exchanger resin Amberlite IRC-50 was charged with histamine by suspension in histamine-containing solution with admixture of [14C]histamine. Mast cell granules were isolated from mast cells suspended in isotonic sucrose. The release of histamine induced from the two materials by superfusion with isotonic NaCl and KCL solutions showed identical kinetics, in accordance with the view that the release of histamine is due to a cation exchange: Na+ (K+) in equilibrium Hi+ at carboxyl groups in the granule heparin-protein complex.
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Cation-induced histamine release from a synthetic weak (carboxylic) cation exchanger resin (IRC-50) and from isolated mast cell granules show identical kinetics. AGENTS AND ACTIONS 1985; 16:129-32. [PMID: 2409760 DOI: 10.1007/bf01983119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Comparative studies between synthetic weak cation exchanger resins and rat mast cell granules have shown that the cation-induced release of histamine from both materials follows the kinetics characteristic of cation exchange. Since also cation-induced release of amines from chromaffin granules in vitro and chromaffin cells in vivo, as also nerve granules of peripheral and central neurons, run according to cation exchange kinetics, cation exchange might be a general principle in the storage and release of biogenic amines.
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