Dynamics of taut DNA chains

We discuss the dynamics of stretched DNA chains, subjected to a tension force f, in a "taut" regime where φ = flp0/kBT > 1 (lp0 being the unperturbed persistence length). We deal with two variables: the local transverse displacements u, and the longitudinal position of a monomer u∥. The variables u and u∥ follow two distinct Rouse equations, with diffusion coefficients D⊥ = f/η (where η is the solvent viscosity) and D∥ = 4φ1/2D⊥. We apply these ideas to a discussion of various transient regimes.