Imaging Hoechst-Labeled Chromosomes and Fluorescent Proteins during the Cell Cycle

INTRODUCTIONFluorescence microscopy provides a powerful tool for imaging molecular components in living cells. Specific molecular components can be efficiently labeled by a combination of three methods: (1) chemical transfection of GFP-fusion constructs, (2) staining of chromosomes with the DNA-specific, fluorescent dye Hoechst 33342, and (3) microinjection of fluorescently conjugated proteins. This procedure provides an example of using all three methods in sequence to label components of living HeLa cells. These methods should be followed in the order presented, but any of them can be omitted when not needed.