Atomic force microscopy: a new way to look at chromatin

This article deals with the application of a new form of microscopy, atomic force microscopy or AFM, to the study of chromatin structure. The main advantage of AFM is that it can operate at subnanometer resolution in aqueous fluids. It has been applied successfully to study of the structural dynamics of cells and molecules. However, thus far most of the AFM work on chromatin has been limited to studies performed in ambient air environments. Even when working in ambient air, AFM offers a number of important advantages over other microscopic techniques: (1) sample preparation is simple, e.g., no stains or metal coatings need to be applied to the specimen; (2) without coatings or stains present, AFM measurements can be made directly on the natural surface of the specimen; (3) imaging can be performed in humid environments where biological specimens remain hydrated with bound water molecules; and (4) the spatial resolution of AFM is sufficient to allow clear visualization of individual nucleosomes and linker DNA.