Ultrastructural characterization of transcriptionally active chromatin by scanning force microscopy

Scanning force microscopy (SFM) was used for ultrastructural characterization of transcriptionally active chromatin. Newt oocyte chromatin was spread hypotonically, fixed and absorbed onto glass substrates prior to air drying. The well-known pattern of active genes was revealed in the topographic contrast of SFM. The measured dimensions for the DNA axis were up to14-16 nm (height) and 40-60 nm (width), for the RNA firbils 8-10 nm (height) and 30-50 nm (width). Due to their specific ultrastructure (i.e. gene length, polarity, repeat) ribosomal genes could be identified