Fluorescent Foci Quantification
Fluorescent Foci Quantification - Related Videos
06:53
Quantification of γH2AX Foci in Response to Ionising Radiation
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Cited by 23 •
2010
Quantification of DNA double-strand streaks using γH2AX formation as a molecular marker has become an invaluable tool in radiation biology. Here we demonstrate the use of an immunofluorescence assay for quantification of γH2AX foci after exposure of cells to radiation.
04:09
Assessing DNA Damage Foci: To Identify Radiation-Induced DNA Damage Foci in Cancer Cell Line Using Immunofluorescence Staining
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2023
This video describes a protocol to detect radiation-induced DNA repair foci in the colon cancer cell lines using immunofluorescence staining. DNA repair proteins get activated at the DNA damage site; therefore, we can detect them using specific antibodies and visualize them under a fluorescence microscope.
02:37
Quantification of Infectious Hepatitis C Virus by Fluorescence Microscopy
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2026
Source: Ren, S., et al. A Protocol for Analyzing Hepatitis C Virus Replication. J. Vis. Exp. (2014)This video demonstrates the fluorescence focus assay used to quantify infectious Hepatitis C virus in cell culture. It demonstrates the serial dilution of viral supernatant, the infection of hepatoma cells, and the detection of viral replication sites using antibody-based fluorescence microscopy.
08:48
Quantitation of γH2AX Foci in Tissue Samples
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Cited by 7 •
2010
Quantitation of DNA double-strand breaks on the basis of γH2AX foci has become an invaluable tool, particularly in radiation biology, for the evaluation of tissue radiosensitivity and effects of radiation modifying compounds. Here we demonstrate the use of an immunofluorescence assay for quantitation of γH2AX foci in tissue samples.
09:33
Methods to Classify Cytoplasmic Foci as Mammalian Stress Granules
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Cited by 33 •
2017
Stress Granules (SGs) are nonmembranous cytoplasmic structures that form in cells exposed to a variety of stresses. SGs contain mRNAs, RNA-binding proteins, small ribosomal subunits, translation-related factors, and various cell signaling proteins. This protocol describes a workflow that uses several experimental approaches to detect, characterize, and quantify bona fide SGs.
FAQs
Fluorescent foci quantification becomes more reliable when background correction is applied before detection. This step reduces surrounding fluorescence that could otherwise obscure the boundary between a focus and its local image background. By clarifying signal contrast, background correction supports more consistent thresholding and object detection, allowing measured focus properties to reflect labeled biological structures rather than unrelated image signal.
Thresholding creates a rule for distinguishing brighter signal from surrounding image content, while object detection identifies the resulting discrete objects. Together, these stages help separate individual foci from nearby fluorescence so that each detected object can be measured. Their role is especially important when the goal is to compare focus number, size, or intensity across biological samples.
The choice of measured property determines the biological question. Focus number can indicate how many discrete structures are detected, whereas size and intensity describe their physical extent and signal strength in the image. Distribution adds spatial context. Considering these measures together can reveal changes in molecular organization or cellular responses that a single metric might miss.
Spatial distribution shows where detected foci occur within cells or samples, rather than only how many are present. This location-related measurement can complement number, size, and intensity by indicating whether molecular structures are arranged differently under different experimental conditions. In biology, that added context helps connect image patterns with changes in molecular organization or cellular responses.
After images are captured, analysis typically proceeds through background correction, thresholding, and object detection. The corrected image is prepared to distinguish labeled signal from surrounding fluorescence, then detected objects are quantified for number, size, intensity, and distribution. Keeping these stages explicit helps turn microscopy observations into numerical measurements suitable for comparisons between biological samples or experimental conditions.
Fluorescent foci quantification can be applied when researchers need to examine DNA repair, protein aggregation, cell signaling, or pathogen infection through fluorescently labeled structures. The measured foci properties provide numerical readouts of molecular organization, activity, or cellular responses. This makes the approach useful for connecting microscopy patterns with biological processes across experimental samples.
By applying the same measurement categories to microscopy images, researchers can record comparable numerical data rather than relying only on visual impressions. Reporting focus number, size, intensity, and distribution across samples makes differences between experimental conditions more explicit. These measurements can therefore support reproducible analysis of changes in cellular responses or molecular organization.