Fluorescent Indicators
Fluorescent Indicators - Related Videos
02:39
Indicators
0 Views •
2020
Certain organic substances change color in dilute solution when the hydronium ion concentration reaches a particular value. For example, phenolphthalein is a colorless substance in any aqueous solution with a hydronium ion concentration greater than 5.0 × 10−9 M (pH < 8.3). In more basic solutions where the hydronium ion concentration is less than 5.0 × 10−9 M (pH > 8.3), it is red or pink. Substances such as phenolphthalein, which can be used to determine the pH of a solution, are called...
11:54
Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator
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Cited by 9 •
2017
Cellular ion transport can often be assessed by monitoring intracellular pH (pHi). Genetically Encoded pH-Indicators (GEpHIs) provide optical quantification of intracellular pH in intact cells. This protocol details the quantification of intracellular pH through cellular ex vivo live-imaging of Malpighian tubules of Drosophila melanogaster with pHerry, a pseudo-ratiometric genetically encoded pH-indicator.
08:17
Water Quality Analysis via Indicator Organisms
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2023
Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba -The University of Arizona Demonstrating Author: Luisa Ikner Water quality analysis monitors anthropogenic influences such as pollutants, nutrients, pathogens, and any other constituent that can impact the water’s integrity as a resource. Fecal contamination contributes microbial pathogens that threaten plant, animal, and human health with disease or illness. Increasing water demands and strict quality standards require that water...
15:16
Loading Drosophila Nerve Terminals with Calcium Indicators
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Cited by 17 •
2007
Calcium is a ubiquitous messenger in the nervous system, essential for triggering neurotransmitter release and changes in synaptic strength. Here we demonstrate a technique for loading Ca2+-indicators into Drosophila nerve terminals. We also demonstrate fabrication of the required apparatus and emphasize points critical for the technique's success.
02:39
Imaging the Mitochondrial Redox State in Primary Neurons Using a Ratiometric Indicator
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2025
Source: Katsalifis, A., et al. Live Imaging of the Mitochondrial Glutathione Redox State in Primary Neurons using a Ratiometric Indicator. J. Vis. Exp. (2021)This video demonstrates the imaging of mitochondrial redox state in primary neurons using a ratiometric fluorescent indicator. By applying two excitation wavelengths under a fluorescence microscope, the fluorescence intensity ratio is measured to assess mitochondrial oxidation. The protocol includes N-methyl-D-aspartate (NMDA) stimulation...
FAQs
In calcium-sensitive indicators, binding between the fluorophore-containing system and calcium alters fluorescence, such as brightness or emission spectrum. Because intracellular calcium changes accompany neural activity, recording these optical changes over time can reveal calcium dynamics within neurons or other selected cells. The resulting signal provides a way to connect cellular activity with patterns of neural signaling.
Voltage-sensitive indicators respond to changes in membrane potential through a voltage-dependent conformational change. That structural shift modifies the fluorescent signal rather than relying on calcium binding. This distinction matters because membrane-potential measurements address electrical changes directly, whereas calcium-sensitive measurements track intracellular calcium dynamics associated with neuronal firing or synaptic signaling.
The two forms differ mainly in how researchers introduce them into selected cells or tissues. Genetically encoded indicators are produced through genetic targeting, while synthetic indicators are supplied as molecules. Both can translate biological changes into fluorescence, but the choice affects how selectively the indicator can be placed within the neural system under study.
A biological interaction can alter either the brightness of an indicator or the wavelengths at which it emits light. Fluorescence microscopy captures these changes as measurable optical signals, allowing researchers to follow neural activity or intracellular calcium dynamics over time. Interpreting which optical change occurs helps relate the recorded signal to the indicator's underlying response mechanism.
A typical workflow introduces a genetically encoded or synthetic indicator into selected cells or tissues, then uses fluorescence microscopy to record changes over time. Researchers select an indicator that responds to the biological variable of interest, such as calcium or membrane potential. The recorded fluorescence is then analyzed to examine neuronal firing, synaptic signaling, or intracellular dynamics.
They are useful when researchers need to connect activity in individual cells with larger neural circuits or behavior. Measurements can support studies of neuronal firing, synaptic signaling, brain development, and disease mechanisms. The same approach can also contribute to investigations of potential therapeutic strategies by showing how cellular activity changes within relevant neural systems.