Role of Membrane Potential in Calcium Signaling During Rhythmic Bursting in Tritonia Swim Interneurons

2007 ◽  
Vol 97 (3) ◽  
pp. 2204-2214 ◽  
Author(s):  
Evan S. Hill ◽  
Paul S. Katz
Keyword(s):  
Membrane Potential ◽  
Action Potentials ◽  
Laser Scanning ◽  
Time Course ◽  
Motor Pattern ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Intracellular Ca ◽  
Potential Waveform

Rhythmic bursting in neurons is accompanied by dynamic changes in intracellular Ca2+ concentration. These Ca2+ signals may be caused by membrane potential changes during bursting and/or by synaptic inputs. We determined that membrane potential is responsible for most, if not all, of the cytoplasmic Ca2+ signal recorded during rhythmic bursting in two neurons of the escape swim central pattern generator (CPG) of the mollusk, Tritonia diomedea: ventral swim interneuron B (VSI) and cerebral neuron 2 (C2). Ca2+ signals were imaged with a confocal laser scanning microscope while the membrane potential was recorded at the soma. During the swim motor pattern (SMP), Ca2+ signals in both neurons transiently increased during each burst of action potentials with a more rapid decay in secondary than in primary neurites. VSI and C2 were then voltage-clamped at the soma, and each neuron's own membrane potential waveform recorded during the SMP was played back as the voltage command. In all regions of VSI, this completely reproduced the amplitude and time course of Ca2+ signals observed during the SMP, but in C2, the amplitude was lower in the playback experiments than during the SMP, possibly due to space clamp problems. Therefore in VSI, the cytoplasmic Ca2+ signal during the SMP can be accounted for by its membrane potential excursions, whereas in C2 the membrane potential excursions can account for most of the SMP Ca2+ signal.

scholarly journals Mitochondrial abnormalities related to the dysfunction of circulating endothelial colony-forming cells in moyamoya disease

2018 ◽  
Vol 129 (5) ◽  
pp. 1151-1159 ◽  
Author(s):  
Jung Won Choi ◽  
Sung Min Son ◽  
Inhee Mook-Jung ◽  
Youn Joo Moon ◽  
Ji Yeoun Lee ◽  
...  
Keyword(s):  
Moyamoya Disease ◽  
Laser Scanning ◽  
Capillary Tube ◽  
Confocal Laser Scanning Microscope ◽  
Tube Formation ◽  
Confocal Laser ◽  
Mitochondrial Morphology ◽  
Mitochondrial Abnormalities ◽  
Endothelial Colony Forming Cells ◽  
Intracellular Ca

OBJECTIVEMoyamoya disease (MMD) is a unique cerebrovascular disorder characterized by the progressive occlusion of the bilateral internal carotid arteries. Endothelial colony-forming cells (ECFCs), previously termed “endothelial progenitor cells,” play an important role in the pathogenesis of MMD. In this study, the authors performed morphological and functional studies of the mitochondria of ECFCs from patients with MMD to present new insights into the pathogenesis of the disease.METHODSThe morphology of ECFCs from 5 MMD patients and 5 healthy controls was examined under both a transmission electron microscope and a confocal laser scanning microscope. The oxygen consumption rates (OCRs), mitochondrial membrane potentials (MMPs), intracellular Ca2+ concentrations, mitochondrial enzyme activities, and reactive oxygen species (ROS) levels were measured. Functional activity of the ECFCs was evaluated using a capillary tube formation assay.RESULTSThe ECFCs from the MMD patients displayed a disrupted mitochondrial morphology, including a shorter and more circular shape. The ECFC mitochondria from the MMD patients exhibited functional abnormalities, which were assessed as a decreased OCR and an increased intracellular Ca2+ concentration. Moreover, the ECFCs from MMD patients showed increased ROS levels. Interestingly, treatment with an ROS scavenger not only reversed the mitochondrial abnormalities but also restored the angiogenic activity of the ECFCs from the MMD patients.CONCLUSIONSThe mitochondria of ECFCs from MMD patients, as compared with those from healthy patients, exhibited morphological and functional abnormalities. This finding suggests that the mitochondrial abnormalities may have a role in the pathogenesis of MMD.

scholarly journals In Vitro Activities of Daptomycin Combined with Fosfomycin or Rifampin on Planktonic and Adherent Linezolid-resistant Enterococcus faecalis

2018 ◽  
Author(s):  
Jin-xin Zheng ◽  
Xiang Sun ◽  
Zhi-wei Lin ◽  
Guo-bin Qi ◽  
Hao-peng Tu ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Adherent Cells ◽  
Planktonic Cells ◽  
Bactericidal Activities ◽  
High Concentrations

AbstractThis study aimed to explore daptomycin combined with fosfomycin or rifampin against the planktonic and adherent linezolid-resistant isolates of Enterococcus faecalis. Four linezolid-resistant isolates of E. faecalis which formed biofilms were collected for this study. Biofilm biomasses were detected by crystal violet staining. The adherent cells in the mature biofilms were counted by CFU numbers and observed by confocal laser scanning microscope (CLSM). In time-killing studies, daptomycin combined with fosfomycin or rifampin (4xMIC) demonstrated bactericidal activities on the planktonic cells, and daptomycin combined with fosfomycin killed more planktonic cells (at least 2-log10 CFU/ml) than daptomycin or fosfomycin alone. Daptomycin alone showed activities against the mature biofilms, and daptomycin combined with fosfomycin (16xMIC) demonstrated significantly more activity than daptomycin or fosfomycin alone against the mature biofilms in three of the four isolates. Daptomycin alone effectively killed the adherent cells, and daptomycin combined with fosfomycin (16xMIC) killed more adherent cells than daptomycin or fosfomycin alone in these mature biofilms. The high concentrations of daptomycin (512 mg/L) combined with fosfomycin indicated more activity than 16xMIC of daptomycin combined with fosfomycin on the adherent cells and the mature biofilms. The addition of rifampin increased the activity of daptomycin against the biofilms and the adherent cells of FB-14 and FB-80 isolates, but was not observed in FB-1 and FB-2 isolates. In conclusion, daptomycin combined with fosfomycin works effectively against the planktonic and adherent linezolid-resistant isolates of E. faecalis. The role of rifampin in these linezolid-resistant isolates is discrepant and needs more studies.

Rapid entry of bitter and sweet tastants into liposomes and taste cells: implications for signal transduction

2000 ◽  
Vol 278 (1) ◽  
pp. C17-C25 ◽  
Author(s):  
Irena Peri ◽  
Hanna Mamrud-Brains ◽  
Sergey Rodin ◽  
Valery Krizhanovsky ◽  
Yechiel Shai ◽  
...  
Keyword(s):  
Signal Transduction ◽  
G Proteins ◽  
Laser Scanning ◽  
Time Course ◽  
Confocal Laser Scanning Microscope ◽  
Taste Buds ◽  
Confocal Laser ◽  
Multilamellar Liposomes ◽  
Taste Cells ◽  
Cell Cytosol

Some amphipathic bitter tastants and non-sugar sweeteners are direct activators of G proteins and stimulate transduction pathways in cells not related to taste. We demonstrate that the amphipathic bitter tastants quinine and cyclo(Leu-Trp) and the non-sugar sweetener saccharin translocate rapidly through multilamellar liposomes. Furthermore, when rat circumvallate (CV) taste buds were incubated with the above tastants for 30 s, their intracellular concentrations increased by 3.5- to 7-fold relative to their extracellular concentrations. The time course of this dramatic accumulation was also monitored in situ in rat single CV taste buds under a confocal laser-scanning microscope. Tastants were clearly localized to the taste cell cytosol. It is proposed that, due to their rapid permeation into taste cells, these amphipathic tastants may be available for activation of signal transduction components (e.g., G proteins) directly within the time course of taste sensation. Such activation may occur in addition to the action of these tastants on putative G protein-coupled receptors. This phenomenon may be related to the slow taste onset and lingering aftertaste typically produced by many bitter tastants and non-sugar sweeteners.

3-D imaging of cells using a confocal laser scanning microscope and digital image processing

1988 ◽  
Vol 46 ◽  
pp. 96-97
Author(s):  
Thomas M. Jovin ◽  
Michel Robert-Nicoud ◽  
Donna J. Arndt-Jovin ◽  
Thorsten Schormann
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Scanning Microscope ◽  
Laser Scanning Microscope ◽  
Biochemical Processes ◽  
Adjacent Structures

Light microscopic techniques for visualizing biomolecules and biochemical processes in situ have become indispensable in studies concerning the structural organization of supramolecular assemblies in cells and of processes during the cell cycle, transformation, differentiation, and development. Confocal laser scanning microscopy offers a number of advantages for the in situ localization and quantitation of fluorescence labeled targets and probes: (i) rejection of interfering signals emanating from out-of-focus and adjacent structures, allowing the “optical sectioning” of the specimen and 3-D reconstruction without time consuming deconvolution; (ii) increased spatial resolution; (iii) electronic control of contrast and magnification; (iv) simultanous imaging of the specimen by optical phenomena based on incident, scattered, emitted, and transmitted light; and (v) simultanous use of different fluorescent probes and types of detectors.We currently use a confocal laser scanning microscope CLSM (Zeiss, Oberkochen) equipped with 3-laser excitation (u.v - visible) and confocal optics in the fluorescence mode, as well as a computer-controlled X-Y-Z scanning stage with 0.1 μ resolution.

3-Dimensional immunolabeling and in situ hybridization detection using fluorescence photooxidation and intermediate-voltage Electron Microscopy

1994 ◽  
Vol 52 ◽  
pp. 164-165
Author(s):  
Thomas J. Deerinck ◽  
Maryann E. Martone ◽  
Varda Lev-Ram ◽  
David P. L. Green ◽  
Roger Y. Tsien ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Reactive Oxygen ◽  
Confocal Laser Scanning Microscope ◽  
Fluorescent Dye ◽  
Confocal Laser ◽  
3 Dimensional ◽  
Voltage Electron ◽  
Dimensional Distribution ◽  
Electron Microscopes ◽  
New Generation

The confocal laser scanning microscope has become a powerful tool in the study of the 3-dimensional distribution of proteins and specific nucleic acid sequences in cells and tissues. This is also proving to be true for a new generation of high contrast intermediate voltage electron microscopes (IVEM). Until recently, the number of labeling techniques that could be employed to allow examination of the same sample with both confocal and IVEM was rather limited. One method that can be used to take full advantage of these two technologies is fluorescence photooxidation. Specimens are labeled by a fluorescent dye and viewed with confocal microscopy followed by fluorescence photooxidation of diaminobenzidine (DAB). In this technique, a fluorescent dye is used to photooxidize DAB into an osmiophilic reaction product that can be subsequently visualized with the electron microscope. The precise reaction mechanism by which the photooxidation occurs is not known but evidence suggests that the radiationless transfer of energy from the excited-state dye molecule undergoing the phenomenon of intersystem crossing leads to the formation of reactive oxygen species such as singlet oxygen. It is this reactive oxygen that is likely crucial in the photooxidation of DAB.

A confocal laser scanning microscope for fluorescence and reflection at video rates

1989 ◽  
Vol 47 ◽  
pp. 134-135
Author(s):  
P.M. Houpt ◽  
A. Draaijer
Keyword(s):  
Light Source ◽  
Laser Scanning ◽  
Focal Point ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Point Light Source ◽  
Volume Of Interest ◽  
Ion Laser ◽  
Point Light ◽  
Point Detector

In confocal microscopy, the object is scanned by the coinciding focal points (confocal) of a point light source and a point detector both focused on a certain plane in the object. Only light coming from the focal point is detected and, even more important, out-of-focus light is rejected.This makes it possible to slice up optically the ‘volume of interest’ in the object by moving it axially while scanning the focused point light source (X-Y) laterally. The successive confocal sections can be stored in a computer and used to reconstruct the object in a 3D image display.The instrument described is able to scan the object laterally with an Ar ion laser (488 nm) at video rates. The image of one confocal section of an object can be displayed within 40 milliseconds (1000 х 1000 pixels). The time to record the total information within the ‘volume of interest’ normally depends on the number of slices needed to cover it, but rarely exceeds a few seconds.

Use of confocal laser scanning microscopy and a computer model to understand ink cavitation and filamentation

TAPPI Journal ◽  
2010 ◽  
Vol 9 (10) ◽  
pp. 7-15
Author(s):  
HANNA KOIVULA ◽  
DOUGLAS BOUSFIELD ◽  
MARTTI TOIVAKKA
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Print Quality ◽  
Length Scale ◽  
Offset Printing ◽  
Significant Difference ◽  
Printing Speed

In the offset printing process, ink film splitting has an important impact on formation of ink filaments. The filament size and its distribution influence the leveling of ink and hence affect ink setting and the print quality. However, ink filaments are difficult to image due to their short lifetime and fine length scale. Due to this difficulty, limited work has been reported on the parameters that influence filament size and methods to characterize it. We imaged ink filament remains and quantified some of their characteristics by changing printing speed, ink amount, and fountain solution type. Printed samples were prepared using a laboratory printability tester with varying ink levels and operating settings. Rhodamine B dye was incorporated into fountain solutions to aid in the detection of the filaments. The prints were then imaged with a confocal laser scanning microscope (CLSM) and images were further analyzed for their surface topography. Modeling of the pressure pulses in the printing nip was included to better understand the mechanism of filament formation and the origin of filament length scale. Printing speed and ink amount changed the size distribution of the observed filament remains. There was no significant difference between fountain solutions with or without isopropyl alcohol on the observed patterns of the filament remains.

scholarly journals Nonlinear absorption and scattering of a single plasmonic nanostructure characterized by x-scan technique

2019 ◽  
Vol 10 ◽  
pp. 2182-2191 ◽  
Author(s):  
Tushar C Jagadale ◽  
Dhanya S Murali ◽  
Shi-Wei Chu
Keyword(s):  
Laser Scanning ◽  
Detection System ◽  
Nonlinear Behavior ◽  
Optical Nonlinearity ◽  
Research Area ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Thin Sample ◽  
Channel Detection ◽  
Novel Method

Nonlinear nanoplasmonics is a largely unexplored research area that paves the way for many exciting applications, such as nanolasers, nanoantennas, and nanomodulators. In the field of nonlinear nanoplasmonics, it is highly desirable to characterize the nonlinearity of the optical absorption and scattering of single nanostructures. Currently, the common method to quantify optical nonlinearity is the z-scan technique, which yields real and imaginary parts of the permittivity by moving a thin sample with a laser beam. However, z-scan typically works with thin films, and thus acquires nonlinear responses from ensembles of nanostructures, not from single ones. In this work, we present an x-scan technique that is based on a confocal laser scanning microscope equipped with forward and backward detectors. The two-channel detection offers the simultaneous quantification for the nonlinear behavior of scattering, absorption and total attenuation by a single nanostructure. At low excitation intensities, both scattering and absorption responses are linear, thus confirming the linearity of the detection system. At high excitation intensities, we found that the nonlinear response can be derived directly from the point spread function of the x-scan images. Exceptionally large nonlinearities of both scattering and absorption are unraveled simultaneously for the first time. The present study not only provides a novel method for characterizing nonlinearity of a single nanostructure, but also reports surprisingly large plasmonic nonlinearities.

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