Distance distribution functions of replication origins in HeLa and glioma human cells according to the data of confocal microscopy

The distribution of replication origins in the nuclei of different cells is studied by confocal microscopy. Based on the obtained images, three-dimensional maps of the positions of the origin centers is constructed and the distribution functions of the pair distances between them are calculated. It is established that the distance distribution function for HeLa and glioma human cells is linear at sizes up to 2 μm, which indicates that the size of the origin system is close to 2. The amplitude of the distance distribution function at small sizes has a power dependence on the nucleus size and is inversely proportional to the nucleus volume to the power of 0.9. Thus, the replication-origin distribution in a nucleus cannot be described by a model with a single Hausdorff dimension in the whole range of sizes.