Viability Dyes
Viability Dyes - Related Videos
02:38
Fluorescence-Based Viability Assessment of Oral Anaerobic Bacteria
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2026
Source: Calatayud Arroyo, M., et al. Assessing the Viability of a Synthetic Bacterial Consortium on the In Vitro Gut Host-microbe Interface. J. Vis. Exp. (2018)The video demonstrates a method to evaluate the viability of anaerobic oral bacteria using fluorescent dyes and flow cytometry. It begins with culturing bacteria in oxygen-free broth, followed by resuspending a single colony from a blood agar plate. After incubation and dilution, the culture is stained with membrane-permeable and...
12:03
Viability Assays for Cells in Culture
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Cited by 39 •
2014
Therapeutic compounds are often first examined in vitro with viability assays. Blind cell counts by a human observer can be highly sensitive to small changes in cell number but do not assess function. Computerized viability assays, as described here, can assess both structure and function in an objective manner.
05:47
Counting and Determining the Viability of Cultured Cells
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Cited by 19 •
2008
Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. In this video, we demonstrate how cells are counted using a hemacytometer.
08:36
FM Dyes in Vesicle Recycling
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2023
FM dyes are a class of fluorescent molecules that has found important use in studying the vesicle recycling process. By virtue of a chemical structure, these molecules can insert themselves into the outer leaflet of phospholipid bilayer membranes. After membrane insertion, they are internalized into the cell via endocytosed vesicles, and released when these vesicles recycle back to the membrane. Since, these dyes fluoresce strongly in the hydrophobic environment within membranes and weakly in...
07:23
Fluorescence Microscopy Methods for Determining the Viability of Bacteria in Association with Mammalian Cells
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Cited by 82 •
2013
Central to the field of bacterial pathogenesis is the ability to define if and how microbes survive after exposure to eukaryotic cells. This article outlines protocols for the use of fluorescent dyes that reveal the viability of individual bacteria inside and associated with host cells.
FAQs
The signal depends on either plasma membrane integrity or intracellular activity. A membrane-impermeant reagent enters cells only when the membrane is compromised, whereas a membrane-permeant indicator can remain within viable cells or undergo intracellular conversion. These different behaviors create distinguishable fluorescence patterns, allowing researchers to separate intact cells from damaged ones during analysis.
Dead or damaged cells can distort measurements of immune-cell phenotype, activation, and function. Excluding them helps distinguish genuine biological responses from changes caused by cell death or membrane damage. This improves interpretation of immunology assays, particularly when infection, treatment, or cytotoxic conditions may alter both cellular activity and survival.
Membrane-impermeant indicators report loss of membrane integrity because they enter cells after damage occurs. Membrane-permeant indicators instead provide a signal associated with viable cells through retention or intracellular conversion. Using these contrasting behaviors helps establish separable live and dead-cell populations, although the interpretation depends on which aspect of cell status the assay is designed to measure.
In flow cytometry, fluorescence from the dye is measured alongside other cellular signals, allowing damaged or dead cells to be identified and excluded from the analysis. This gating strategy helps prevent nonviable events from influencing immune-cell phenotyping, activation, or functional measurements. The resulting data more closely reflect responses from cells that remain viable.
Fluorescence microscopy uses the different signals from viability dyes to visualize cell survival and damage directly in the examined sample. Researchers can assess whether cells retain a viable-associated signal or acquire a damage-associated signal, supporting evaluation of cytotoxicity and pathogen-induced injury. This complements flow-based measurements when visual information is important.
They are useful when researchers need to determine whether an observed cellular response reflects immune activity or loss of cell integrity. During infection studies, the dyes can help monitor pathogen-induced cell damage and survival. In treatment experiments, they support cytotoxicity assessment and clarify whether changes in phenotype or function occur among surviving cells.