Localized electroporation: A method for targeting expression of genes in avian embryos

Avian embryos are a popular model for cell and developmental biologists. Ho wever, analysis of gene function in living embryos has been hampered by dif ficulties ill targeting thf expression of exogenous genes. We have develope d a method for localized electroporation that overcomes some of the limitat ions of current techniques. We use a double-barreled suction electrode, bac kfilled with a solution containing a plasmid-encoding green fluorescent pro tein (GFP) and a neurophysiological stimulator to electroporate small popul ations of cells in living embryos. As many ns 600 cells express GFP 24-48 h after electroporation. The number of cells that express GFP depends on the number of trains, the pulse frequency and the voltage. Surface epithelial cells and cells deep to the point electroporation express GFP No deformitie s result from electroporations, and neurons, neural crest, head mesenchyme, lens and otic placode cells have been transfected. This method overcomes s ome of the disadvantages of viral techniques, lipofection and in vivo elect roporation. The method will be useful to biologists interested in tracing c ell lineage or making genetic mosaic avian embryos.