Phase Transition and Phase Segregation in a Single Double-Stranded DNA Molecule

Abstract
From the single-molecule observation of a long DNA chain, T4 DNA (166 kbp), by fluorescence microscopy, we found that an individual chain exhibits a first-order phase transition between an elongated coil and a compact globule with a change in the concentration of alcohol added to the aqueous environment. In the globule phase near the transition point, a metastable state is observed in which the globular and coil states coexist within a single DNA chain, i.e., phase separation is induced along a single chain.