Figure 1.

Definitions and measurements of shape anisotropy and orientation of fluorescently labeled DNA molecules probed via light microscopy (A) Nonspherical shape of a random-walk polymer, as predicted by Kuhn (6) and observed in this study. The best-fit ellipse encompasses all segments of the polymer and defines the lengths of the large axis and the minor axis, l_major and l_minor, respectively, as well as the angle of orientation, θ. (B) Sampled values of the orientation of polymers chosen at random in different fields of view and different samples. (C) Distribution of the angle of orientation of a large ensemble of flexible polymers.