Illuminating EM with GFP

The ability to use GFP-tagged proteins to perform correlative light and electron microscopy has been a desirable but elusive method. The high quantum yield of GFP that makes it excellent for fluorescence imaging also makes it extremely inefficient for production of the reactive oxygen needed to trigger formation of an electron-dense precipitate for electron microscopy. This roadblock has finally been overcome by Grabenbauer, Nilsson and colleagues who describe several modifications to the standard method of correlative microscopy using diaminobenzidine (DAB) precipitation. These changes greatly increase oxygen radical production, thus allowing fluorescent proteins to produce enough DAB precipitate for visualization by electron microscopy. Article p857