Extended Data Fig. 3: STORM analysis of paired Drosophila homologues.

a, Schematic of expected outcomes from STORM if chromosomes are tightly paired and follow a similar trajectory, or are loosely paired and follow distinct trajectories that are within a diffraction-limited distance of one another. b, Representative images from STORM of paired homologues labelled with ORCA barcode 69. Similar images were observed for all barcodes shown in c, d. Centres from 3D Gaussian fitting of the point spread function are represented as plus symbols on spots. Occasional double peaks occur at a frequency similar to that of background non-specific localizations; these may represent stray probes, noise in peak detection of weakly labelled loci, or split homologues. c, d, Quantification of the frequency of single peak detection for 10 kb (c) and 3 kb (d) per barcode. The high level of single peak detection is indicative of the tightly paired homologues for the BX-C. For the boxplots in c, d, the red line marks the median, the upper and lower limits of the boxes mark the interquartile range, and the whiskers extend to the farthest data points within 1.5 times the interquartile range. Number of foci (n) is indicated below each box plot.