Electrical and optical monitoring of alpha-latrotoxin action at Drosophila neuromuscular junctions.
AuthorsUmbach JA, Grasso A, Zurcher SD, Kornblum HI, Mastrogiacomo A, Gundersen CB
JournalNeuroscience
PubMed ID9759979
'Electrophysiological recording demonstrates that alpha-latrotoxin, a 125,000 mol. wt component of black widow spider venom, promotes high frequency quantal discharges at larval neuromuscular junctions of Drosophila. Concomitantly, fluorescence imaging of presynaptic calcium ion activity reveals that this toxin qualitatively elevates cytosolic ionized calcium in this preparation. These activities of alpha-latrotoxin ... More
The role of Ca(2+) in stimulated bioluminescence of the dinoflagellate Lingulodinium polyedrum.
Authorsvon Dassow P, Latz MI
JournalJ Exp Biol
PubMed ID12200401
'Many marine dinoflagellates emit bright discrete flashes of light nearly instantaneously in response to either laminar or turbulent flows as well as to direct mechanical stimulation. The flash involves a unique pH-dependent luciferase and a proton-mediated action potential across the vacuole membrane. The mechanotransduction process initiating this action potential is ... More
Cysteine-string protein increases the calcium sensitivity of neurotransmitter exocytosis in Drosophila.
AuthorsDawson-Scully K, Bronk P, Atwood HL, Zinsmaier KE
JournalJ Neurosci
PubMed ID10934253
'Previous studies suggest that the vesicular cysteine-string protein (CSP) may modulate presynaptic Ca(2+) channel activity in fast neurotransmitter release. To test this hypothesis, we analyzed the dynamics of presynaptic Ca(2+) ion influx with the Ca(2+) indicator fluo-4 AM at csp mutant neuromuscular junctions of Drosophila. From 24 to 30 degrees ... More
Cell-permeant Ca2+ chelators reduce early excitotoxic and ischemic neuronal injury in vitro and in vivo.
AuthorsTymianski M, Wallace MC, Spigelman I, Uno M, Carlen PL, Tator CH, Charlton MP
JournalNeuron
PubMed ID8102532
'We report the characterization of the first successful treatment of neuronal ischemic injury in vivo by cell-permeant Ca2+ chelators. The chelators attenuated glutamate-induced intracellular Ca2+ increases and neurotoxicity in neuronal explant cultures. When infused intravenously in rats, permeant fluorescent BAPTA analogs accumulated in neurons in several brain regions. BAPTA-AM, infused ... More
A non-radioactive receptor assay for snake venom postsynaptic neurotoxins.
AuthorsStiles BG
JournalToxicon
PubMed ID1862522
'A non-radioactive assay was developed for detecting the binding of postsynaptic neurotoxins to acetylcholine receptor (AchR) from Torpedo californica. Enzyme linked immunosorbent assay (ELISA) wells coated with long or short chain neurotoxins specifically bound to purified AchR while crotamine or two different cardiotoxins did not. Bound receptor was detected by ... More
Ryanodine receptor regulation by intramolecular interaction between cytoplasmic and transmembrane domains.
AuthorsGeorge CH, Jundi H, Thomas NL, Scoote M, Walters N, Williams AJ, Lai FA
JournalMol Biol Cell
PubMed ID15047862
'Ryanodine receptors (RyR) function as Ca(2+) channels that regulate Ca(2+) release from intracellular stores to control a diverse array of cellular processes. The massive cytoplasmic domain of RyR is believed to be responsible for regulating channel function. We investigated interaction between the transmembrane Ca(2+)-releasing pore and a panel of cytoplasmic ... More
Attenuated influx of calcium ions at nerve endings of csp and shibire mutant Drosophila.
AuthorsUmbach JA, Saitoe M, Kidokoro Y, Gundersen CB
JournalJ Neurosci
PubMed ID9547232
'Previous work has shown that cysteine-string proteins (csps) are synaptic vesicle proteins that are important for evoked neurotransmitter release at Drosophila neuromuscular junctions. Indirect evidence has implicated csps in a regulatory link between synaptic vesicles and presynaptic calcium (Ca) channels. In this report, we use Ca Crimson to monitor stimulus-dependent ... More
Excitation spectra and brightness optimization of two-photon excited probes.
'Two-photon probe excitation data are commonly presented as absorption cross section or molecular brightness (the detected fluorescence rate per molecule). We report two-photon molecular brightness spectra for a diverse set of organic and genetically encoded probes with an automated spectroscopic system based on fluorescence correlation spectroscopy. The two-photon action cross ... More
Ion transport across model lipid membranes containing light-harvesting complex II: an effect of light.
AuthorsIwaszko E, Wardak A, Krupa Z, Gruszecki WI
JournalJ Photochem Photobiol B
PubMed ID15043842
'The effect of light on proton transport across lipid membranes of small unilamellar liposomes containing incorporated major light-harvesting pigment-protein complex of Photosystem II (LHCII) has been studied with the application of pH-sensitive dyes entrapped inside vesicles. Proton permeability coefficient for LHCII-modified membranes was found to be about twice as high ... More
Intracellular ionized calcium.
AuthorsJune CH, Rabinovitch PS
JournalMethods Cell Biol
PubMed ID7861962
Adenosine induces inositol 1,4,5-trisphosphate receptor-mediated mobilization of intracellular calcium stores in basal forebrain cholinergic neurons.
AuthorsBasheer R, Arrigoni E, Thatte HS, Greene RW, Ambudkar IS, McCarley RW
JournalJ Neurosci
PubMed ID12196591
In the cholinergic basal forebrain, we found previously that the extracellular adenosine concentration increase that accompanies sleep deprivation, acting via the A1 receptor, led to activation of the transcription factor nuclear factor-kappaB and to the upregulation of A1 adenosine receptor mRNA. We thus began to examine intracellular signaling mechanisms. We ... More
Techniques for measuring and manipulating free Ca2+ in the cytosol and organelles of neutrophils.
AuthorsHallett MB, Hodges R, Cadman M, Blanchfield H, Dewitt S, Pettit EJ, Laffafian I, Davies EV
JournalJ Immunol Methods
PubMed ID10618511
Ca(2+) signalling in neutrophils is important for triggering and coordinating the behaviour of neutrophils. Fluorescent probes for cytosolic free Ca(2+) concentration, e.g., fura2 and fluo3, have been widely used in neutrophils. These probes can be used to monitor Ca(2+) in the cytosol, the nucleus, near the plasma membrane and theoretically ... More
Mouse mast cell secretory granules can function as intracellular ionic oscillators.
AuthorsQuesada I, Chin WC, Steed J, Campos-Bedolla P, Verdugo P
JournalBiophys J
PubMed ID11325716
Fluorescent Ca2+ probes and digital photo-sectioning techniques were used to directly study the dynamics of Ca2+ in isolated mast cell granules of normal (CB/J) and beige (Bg(j)/Bg(j)) mice. The resting intraluminal free Ca2+ concentration ([Ca2+]L) is 25 +/- 4.2 microM (mean +/- SD, n = 68). Exposure to 3 microM ... More
Synaptic vesicles: test for a role in presynaptic calcium regulation.
Membrane-bound organelles such as mitochondria and the endoplasmic reticulum play an important role in neuronal Ca(2+) homeostasis. Synaptic vesicles (SVs), the organelles responsible for exocytosis of neurotransmitters, occupy more of the volume of presynaptic nerve terminals than any other organelle and, under some conditions, can accumulate Ca(2+). They are also ... More
ATP-independent luminal oscillations and release of Ca2+ and H+ from mast cell secretory granules: implications for signal transduction.
AuthorsQuesada I, Chin WC, Verdugo P
JournalBiophys J
PubMed ID12885643
InsP(3) is an important link in the intracellular information network. Previous observations show that activation of InsP(3)-receptor channels on the granular membrane can turn secretory granules into Ca(2+) oscillators that deliver periodic trains of Ca(2+) release to the cytosol (T. Nguyen, W. C. Chin, and P. Verdugo, 1998, Nature, 395:908-912; ... More
Gravitaxis and graviperception in flagellates.
AuthorsHader DP, Lebert M, Richter P, Ntefidou M
JournalAdv Space Res
PubMed ID14686430
There is strong evidence that gravitactic orientation in flagellates and ciliates is mediated by an active physiological gravireceptor rather than by passive alignment of the cells in the water column. In flagellates the threshold for graviorientation was found to be at 0.12 x g on a slow rotating centrifuge during ... More
Relocalization of the calcium gradient and a dihydropyridine receptor is involved in upward bending by bulging of Chara protonemata, but not in downward bending by bowing of Chara rhizoids.
AuthorsBraun M, Richter P
JournalPlanta
PubMed ID10550622
The localization of cytoplasmic free calcium and a dihydropyridine (DHP) receptor, a putative calcium channel, was recorded during the opposite graviresponses of tip-growing Chara rhizoids and Chara protonemata by using the calcium indicator Calcium Crimson and a fluorescently labeled dihydropyridine (FL-DHP). In upward (negatively gravitropically) growing protonemata and downward (positively ... More
Fluorescence studies suggest a role for alpha-synuclein in the phosphatidylinositol lipid signaling pathway.
AuthorsNarayanan V, Guo Y, Scarlata S
JournalBiochemistry
PubMed ID15641770
Alpha-synuclein plays a key role in the pathogenesis of many neurodegenerative diseases. To date, its cellular role has yet to be determined, although it has been proposed to be connected to calcium and G protein-mediated dopamine signaling. Alpha-synuclein is known to bind strongly to model membrane surfaces where it may ... More
Transmitter release from presynaptic terminals of electric organ: inhibition by the calcium channel antagonist omega Conus toxin.
AuthorsYeager RE, Yoshikami D, Rivier J, Cruz LJ, Miljanich GP
JournalJ Neurosci
PubMed ID3112325
Cholinergic synaptosomes from electroplax of the ray Ommata discopyge release both ATP and ACh when depolarized with high K+ concentration in the presence of Ca2+. Others have shown that the ATP and ACh are released in the molar ratio found in isolated synaptic vesicles. Thus, it is assumed that the ... More
Dynamics of glucose-induced membrane recruitment of protein kinase C beta II in living pancreatic islet beta-cells.
The mechanisms by which glucose may affect protein kinase C (PKC) activity in the pancreatic islet beta-cell are presently unclear. By developing adenovirally expressed chimeras encoding fusion proteins between green fluorescent protein and conventional (betaII), novel (delta), or atypical (zeta) PKCs, we show that glucose selectively alters the subcellular localization ... More
Modulation of spike-mediated synaptic transmission by presynaptic background Ca2+ in leech heart interneurons.
AuthorsIvanov AI, Calabrese RL
JournalJ Neurosci
PubMed ID12598609
At the core of the rhythmically active leech heartbeat central pattern generator are pairs of mutually inhibitory interneurons. Synaptic transmission between these interneurons consists of spike-mediated and graded components, both of which wax and wane on a cycle-by-cycle basis. Low-threshold Ca2+ currents gate the graded component. Ca imaging experiments indicate ... More
Acute stress results in skin corticotropin-releasing hormone secretion, mast cell activation and vascular permeability, an effect mimicked by intradermal corticotropin-releasing hormone and inhibited by histamine-1 receptor antagonists.
AuthorsLytinas M, Kempuraj D, Huang M, Boucher W, Esposito P, Theoharides TC
JournalInt Arch Allergy Immunol
PubMed ID12660427
BACKGROUND: Mast cells play an important role in allergic inflammation by releasing vasoactive molecules, proteases and cytokines. Corticotropin-releasing hormone (CRH) and its structural analogue urocortin (Ucn) were shown to trigger skin mast cell activation and vascular permeability. We investigated the effect of acute stress on rat skin vascular permeability and ... More