Analysis of Chromatin by Scanning Force Microscopy

While much is known about the structure of the nucleosome, how a chain of contiguous nucleosomes rearranges to form a fiber is much less understood. Microscopical techniques with nucleosomal resolution (electron microscopy and the newly emerging probe microscopies) have been useful in understanding chromatin fiber structure. The most widely used probe microscopy for biological applications, the scanning force microscope (SFM), also known as the atomic force microscope, is capable of imaging samples under very mild conditions (for recent reviews, see refs. 1 –3 ). Samples are not stained or shadowed or subjected to vacuum and are imaged under ambient room temperature conditions in air or in aqueous buffer.