Origins of Ca2+ Imaging with Fluorescent Indicators

Biochemistry ◽  
2021 ◽  
Author(s):  
Xinqi Zhou ◽  
Kayla J. Belavek ◽  
Evan W. Miller
Keyword(s):  
Fluorescent Indicators

Increased Aggregation and Secretion Responses of Human Platelets when Loaded with the Calcium Fluorescent Probes Quin2 and Fura-2

1987 ◽  
Vol 58 (02) ◽  
pp. 737-743 ◽  
Author(s):  
Frarnçois Lanza ◽  
Alain Beretz ◽  
Martial Kubina ◽  
Jean-Pierre Cazenave
Keyword(s):  
Intracellular Calcium ◽  
Shape Change ◽  
Calcium Ionophore ◽  
Human Platelets ◽  
Arachidonic Acid Metabolism ◽  
Free Calcium ◽  
Membrane Bilayer ◽  
Fluorescent Indicators ◽  
Fura 2 ◽  
Low Concentrations

SummaryIncorporation into human platelets of the calcium fluorescent indicators quin2 or fura-2 at low concentrations used to measure intracellular free calcium leads to the potentiation of the effects of agonists on platelets. This was shown by increased aggregatory and secretory responses of quin2 or fura-2 loaded platelets after stimulation with ADP, PAP and with low concentrations of thrombin, collagen, the endoperoxide analog U-46619 and the calcium ionophore A 23187. Quin2 and fura-2 mediated platelet sensitisation could be due to altered arachidonic acid metabolism since it was inhibited by prior treatment with the cydooxygenase inhibitor acetylsalicylate. In contrast, platelets loaded with higher concentrations of calcium chelators exhibited diminished aggregation responses to all aggregating agents. This latter effect was accompanied by increased fluidity of the platelet plasma membrane bilayer and by the exposure of a new pool of membranes to the outer surface of platelets, as monitored with trimethylammonium- diphenylhexatriene (TMA-DPH) in platelets loaded with the non-fluorescent calcium probe analog MAPT. In contrast, low concentrations of quin2 did not potentiate shape change of platelets activated with ADP. Thus, shape change and aggregation can be influenced separately by intracellular Ca2+ chelators. We conclude that platelet responses are altered by the incorporation of intracellular calcium chelators at concentrations used to monitor intracellular calcium changes.

Optimization of sol-gel based fibre-optic cholinesterase biosensor for the determination of organophosphorus pesticides

2000 ◽  
Vol 42 (7-8) ◽  
pp. 283-290 ◽  
Author(s):  
H.-C. Tsai ◽  
R.-A. Doong
Keyword(s):  
Fiber Optic ◽  
Ph Value ◽  
Rapid Determination ◽  
Organophosphorus Pesticides ◽  
Sol Gel ◽  
Neutral Red ◽  
Fluorescent Indicators ◽  
Low Leakage ◽  
Fiber Optic System

A sol-gel based fiber-optic biosensor with acetylcholinesterase as the biorecognition element has been developed for the rapid determination of organophosphorus pesticides. Nine fluorescent indicators, acridine, acridine orange, neutral red, DAPI, rhodamine B, fluorescein, umbelliferone, FITC on celite and FITC-dextran, have been examined to optimize the fiber-optic system. Results showed that acridine and FITCs were sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. However, the sensitivity of acridine was 260 times lower than that of FITCs. Higher toxicity of acridine to acetylcholinesterase than FITC was also observed. Moreover, the high-molecular-weight FITC-dextran showed low leakage rate when immobilizing using sol-gel technology, showing that the FITC-dextran was a suitable pH sensitive fluorescent indicator for the OPPs biosensor. The response of the fiber-optic biosensor to the substrate, acetylcholine, was highly reproducible (RSD=3.5%). A good linearity of acetylcholine in the range from 0.5 to 20 mM was also obtained (R2=0.98). Furthermore, a 30% inhibition can be achieved in 30min when 152 ppb paraoxon was added into the system. The results show the possibility for real-time determination of organophosphorus pesticides by using the biosensor developed in this study.

scholarly journals A photocross-linking fluorescent indicator of mitochondrial membrane potential.

1993 ◽  
Vol 41 (4) ◽  
pp. 631-634 ◽  
Author(s):  
K M Hahn ◽  
P A Conrad ◽  
J C Chao ◽  
D L Taylor ◽  
A S Waggoner
Keyword(s):  
Membrane Potential ◽  
Electrical Potential ◽  
Living Cells ◽  
Covalent Attachment ◽  
Cross Linking ◽  
Mitochondrial Potential ◽  
Specific Staining ◽  
Fluorescent Indicators ◽  
3T3 Fibroblasts ◽  
Mitochondrial Staining

Ionic dyes that distribute across membranes according to electrical potential have proven valuable as fluorescent indicators of mitochondrial energetics in living cells. Applications have been limited, however, as potential-dependent staining is lost during cell fixation. We have produced a membrane potential indicator whose potential-dependent distribution can be made permanent, to enable correlation of membrane potential with cytochemical information from immunofluorescence. A carbocyanine dye was derivatized with a photoreactive nitrophenylazide moiety so that irradiation would induce nonspecific, covalent attachment to nearby molecules. Photo-induced cross-linking was observed in paper chromatography, when irradiation caused immobilization of the dye. The new dye, named PhoCy (photofixable cyanine), showed specific staining of mitochondria in living Swiss 3T3 fibroblasts. When living cells were stained, irradiated, and fixed with formaldehyde, mitochondrial staining was retained owing to cross-linking with mitochondrial components. Omission of irradiation eliminated mitochondrial staining in fixed cells. Labeling, irradiation, and fixation procedures were optimized to produce bright specific staining with minimal background. The indicator's sensitivity to mitochondrial potential was demonstrated by treating cells with 2,4-dinitrophenol, an uncoupler of mitochondrial electron transport, which decreased mitochondrial staining in living cells and in the corresponding fixed specimens.

Synthesis and characterization of dual-wavelength Cl−-sensitive fluorescent indicators for ratio imaging

1999 ◽  
Vol 276 (3) ◽  
pp. C747-C757 ◽  
Author(s):  
Sujatha Jayaraman ◽  
Joachim Biwersi ◽  
A. S. Verkman
Keyword(s):  
First Generation ◽  
Spectral Characteristics ◽  
Dual Wavelength ◽  
Reduced Form ◽  
Excitation Wavelength ◽  
Transmembrane Conductance Regulator ◽  
Fluorescent Indicators ◽  
3T3 Fibroblasts ◽  
Ratio Imaging ◽  
Ratiometric Measurement

The fluorescence of quinolinium-based Cl− indicators such as 6-methoxy- N-(3-sulfopropyl)quinolinium (SPQ) is quenched by Cl− by a collisional mechanism without change in spectral shape. A series of “chimeric” dual-wavelength Cl− indicators were synthesized by conjugating Cl−-sensitive and -insensitive chromophores with spacers. The SPQ chromophore (N-substituted 6-methoxyquinolinium; MQ) was selected as the Cl−-sensitive moiety [excitation wavelength (λex) 350 nm, emission wavelength (λem) 450 nm]. N-substituted 6-aminoquinolinium (AQ) was chosen as the Cl−-insensitive moiety because of its different spectral characteristics (λex 380 nm, λem 546 nm), insensitivity to Cl−, positive charge (to minimize quenching by chromophore stacking/electron transfer), and reducibility (for noninvasive cell loading). The dual-wavelength indicators were stable and nontoxic in cells and were distributed uniformly in cytoplasm, with occasional staining of the nucleus. The brightest and most Cl−-sensitive indicators were α-MQ-α′-dimethyl-AQ-xylene dichloride and trans-1,2-bis(4-[1-α′-MQ-1′-α′-dimethyl-AQ-xylyl]-pyridinium)ethylene (bis-DMXPQ). At 365-nm excitation, emission maxima were at 450 nm (Cl− sensitive; Stern-Volmer constants 82 and 98 M−1) and 565 nm (Cl−insensitive). Cystic fibrosis transmembrane conductance regulator-expressing Swiss 3T3 fibroblasts were labeled with bis-DMXPQ by hypotonic shock or were labeled with its uncharged reduced form (octahydro-bis-DMXPQ) by brief incubation (20 μM, 10 min). Changes in Cl− concentration in response to Cl−/nitrate exchange were recorded by emission ratio imaging (450/565 nm) at 365-nm excitation wavelength. These results establish a first-generation set of chimeric bisquinolinium Cl− indicators for ratiometric measurement of Cl− concentration.

Presynaptic calcium signals during neurotransmitter release: Detection with fluorescent indicators and other calcium chelators

1992 ◽  
Vol 86 (1-3) ◽  
pp. 129-134 ◽  
Author(s):  
GJ Augustine ◽  
EM Adler ◽  
MP Charlton ◽  
M Hans ◽  
D Swandulla ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Calcium Signals ◽  
Fluorescent Indicators ◽  
Presynaptic Calcium

High-throughput pH monitoring method for application in dairy fermentations

2018 ◽  
Vol 85 (4) ◽  
pp. 453-459
Author(s):  
Valery Gutsal ◽  
Sander Sieuwerts ◽  
Rodrigo Bibiloni
Keyword(s):  
Ph Monitoring ◽  
Starter Cultures ◽  
New Method ◽  
Monitoring Method ◽  
Fluorescent Indicators ◽  
Optical Ph Sensors ◽  
Dairy Starter Cultures ◽  
Electrode Systems ◽  
Dairy Starter ◽  
Dairy Fermentation

Optimization of dairy fermentation processes often requires multiplexed pH measurements over several hours. The method developed here measures up to 90 samples simultaneously, where traditional electrode-based methods require a lot more time for handing the same number of samples. Moreover, the new method employs commonly used materials and can be used with a wider range of fluorescence readers than commercial 96-well plates with optical pH sensors. For this application, a milk-like transparent medium is developed that shows acidification properties with dairy starters that are similar to milk. Combination of this milk-like medium and 3 fluorescent indicators allow precise measurements of pH in a range of 4·0–7·0. The new method showed much higher throughput compared to the benchmark electrode systems while being as accurate, as shown by successful application for a comparison of various dairy starter cultures and for optimizing the inoculation rate.

Fluorescent indicators for inositol 1,4,5-trisphosphate based on bioconjugates of pleckstrin homology domain and fluorescent dyes

1999 ◽  
Vol 36 (5) ◽  
pp. 175-177 ◽  
Author(s):  
Kenzo Hirose ◽  
Hiroshi Takeshima ◽  
Masamitsu Iino ◽  
Kenzo Hirose ◽  
Hiroshi Takeshima ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Pleckstrin Homology Domain ◽  
Pleckstrin Homology ◽  
Fluorescent Indicators ◽  
Inositol 1,4,5 Trisphosphate

Cerebral anoxia tolerance in turtles: regulation of intracellular calcium and pH

1992 ◽  
Vol 263 (6) ◽  
pp. R1298-R1302
Author(s):  
P. E. Bickler
Keyword(s):  
Intracellular Calcium ◽  
Brain Slices ◽  
Calcium Flux ◽  
Anoxia Tolerance ◽  
Acetoxymethyl Ester ◽  
Fluorescent Indicators ◽  
Cerebral Anoxia ◽  
Atp Production ◽  
Laboratory Rats ◽  
Inhibition Of Glycolysis

To investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([Ca2+]i) and pH (pHi) regulation were compared in turtles (Trachemys scripta) and laboratory rats. [Ca2+]i and pHi in living 200 to 300-microns-thick cortical brain slices were measured with the fluorescent indicators fura-2/acetoxymethyl ester (AM) and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein during exposure to anoxia. Within 5 min, [Ca2+]i increased to > 1,000 nM in rat brain slices exposed to anoxia but [Ca2+]i was normal even after 5 h of anoxia in turtles. ATP levels remained normal in anoxic turtle brain but fell rapidly in rats. During anoxia, pHi fell by 0.25 +/- 0.08 pH units in rats but only 0.10 +/- 0.04 in turtles (P < 0.05). Inhibition of glycolysis in anoxic turtle brain with iodoacetate resulted in large increases in [Ca2+]i but prior exposure of slices to anoxia resulted in greatly attenuated calcium entry. The reduction in calcium flux was greater with increasing exposure to anoxia, suggesting progressive arrest of calcium channel activity. Tolerance of cerebral anoxia in turtles may be related to anaerobic ATP production, arrest of calcium channels, and attenuation of changes in pHi.

ChemInform Abstract: Fluorescent Indicators Based on BODIPY

ChemInform ◽  
2012 ◽  
Vol 43 (17) ◽  
pp. no-no
Author(s):  
Noel Boens ◽  
Volker Leen ◽  
Wim Dehaen
Keyword(s):  
Fluorescent Indicators
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