Individual macromolecules: preparation and recent results with DNA

Protein-monolayer techniques are described which permit visualization of individual nucleic acid molecules by electron microscopy. The range of application is demonstrated by examples of quantitative observations concerning intrinsic and artificially introduced properties of DNA molecules, namely size and shape; binding of the drug ethidium bromide; diffusion coefficient; physical mapping of genetic deletions, adenine-thymine rich regions, single-strand breaks, and sites of messenger RNA synthesis.