Abstract
Fluorescence Activated Cell Sorting (FACS) is used to study DNA cell content. Propidium iodide (PI) intercalates into double-stranded nucleic acids and fluoresces. It is excluded by viable cells but can penetrate cell membranes of dying or dead cells. Thus PI staining is included in immunofluorescent staining protocols to identify dead cells. DNA staining can be used to study the cell cycle. Relative DNA content shows the proportion of cells in G1, G2 and S phases. Apoptotic cells show characteristic smear on DNA staining. Here a protocol to stain cells by PI is described.
Keywords: Propidium iodide, FACS, Cell cycle
Materials and Reagents
Equipment
Procedure
Recipes
Acknowledgments
This protocol was developed in the laboratory of Dr. Guowei Fang (Department of Biology, Stanford University, Stanford, CA, USA). This work was supported by a Burroughs-Wellcome Career Award in Biomedical Research (G.F.) and by grants from National Institutes of Health (GM062852 to G.F.).
References
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Triton X-100 is used as permeabilization buffer to penetrate cells. If you don’t penetrate cells, Propidium Iodide won’t stain well.
You can also use a hypotonic buffer instead of Triton X-100 to permeabilize the cells.