Propidium iodide staining of Drosophila embryos

INTRODUCTIONDrosophila embryos can be stained with specific fluorescent probes or antibodies through either direct or indirect immunofluorescence. In particular, several effective probes exist for visualizing DNA. Propidium iodide (PI), a stain commonly used to visualize nucleic acids, is added directly to the mounting medium. Before staining with PI, the embryos must be treated with RNase to remove the RNA. This protocol presents methods for staining Drosophila embryos with PI, as well as for the subsequent mounting and storage of samples.