Mouse sperm cells Hi-C data

The 3D organization of the genome is tightly connected to its biological function. The Hi-C was introduced recently as a method for identifying higher order chromatin interactions genome wide. Aim of this study is determination of genome-wide chromatin interaction frequencies by the Hi-C approach in mouse mature sperm cells and embryonic fibroblasts. The obtained results demonstrated that 3D genome organization of mouse sperm and fibroblast cells show a high degree of similarity with each other and previously described mouse embryonic stem (ES) cells. Both A/B compartments and topological domains described earlier for other cell types are present in sperm cells. However, sperm cells and fibroblasts exhibited statistically significant differences in contact probabilities of defined loci. Tight packaging of sperm cells genome resulted in enrichment of long-range contacts in comparison to fibroblasts. Also, only 30% of differences in the number of contacts are based on differences in densities of their genome package, whereas the main source of differences is gain or loss of contacts specific for defined genome regions. Analysis of interchromosomal contacts in spermatozoa and fibroblasts revealed that large chromosomes have tendency to be co-localized within a nuclei, as well as small chromosomes. We found that the dependence of the contact probability P(s) on genomic distance for sperm is in agreement with fractal globule folding of chromatin. The similarity of the spatial DNA organization in sperm and somatic cell can serves the base for stability of 3D structure of genome through generations.