Fig. 1

Advances in imaging techniques allow rich information about chromatin beyond Hi-C. Chromatin is constantly remodeled during time (top to bottom), which is illustrated on the basis of a short polymer which changes its configuration over time (left). A single-cell Hi-C-like type of data over time of this polymer would reveal relatively few contacts at each time point for single cells as the technique relies on proximity ligation (middle column). In contrast, imaging offers the determination of actual positions and distances between any two loci in three dimensions and thus reveals a more complete picture than “C” methods (right column). The illustrative maps were created by tracing the contour of the polymer shown on the left and computing the pairwise distance between any two loci which is shown in the imaging-like matrix. The Hi-C map is a thresholded version of the distance map and shows contacts only at small spatial distances. Yet, note that there may be a broad distance distribution underlying measured Hi-C contacts [36], and as such, the illustration is highly simplified. The Hi-C map is a thresholded version of the distance map and shows contacts only at small spatial distances. While imaging chromatin at many loci simultaneously is currently, with a few exceptions, done in fixed cells, it has the potential to advance toward analysis in living cells in the future. However, a single-cell time evolution of chromatin structure by Hi-C cannot be obtained since Hi-C is a destructive method