Figure 2.
Measurements of chromosome persistence length. In vitro condensed chromosomes were dispersed between two coverglasses and images of freely fluctuating chromosomes were recorded on an S-VHS video recorder. (a) Digitized images of a chromosome, where the computed 1-pixel-thick central skeleton is highlighted (interval between images: 3 s); (b) angle θ (s) between tangents at points separated by an arc of length s. (c) The average over 5,000 images of 16 chromosomes of cos(θ(s)) versus s curve (tangent autocorrelation function). The curve is fitted by exp(−s/2L p), where L p = 2.7 ± 0.1 μm. Chromosomes were visualized by phase-contrast or fluorescent microscopy with Hoechst 258 used for labeling. (Inset) Number of samples used to perform the average, as a function of arc length.