On the role of replication and cohesion in shaping the 4D Genome

How replication and sister chromatid cohesion interplay with the spatio-temporal organization of chromosomes remains elusive. From the local structure of two diverging sister-forks to the relative folding of sister chromatids and the higher-level organization of the replication machinery into nuclear domains, the mechanistic details of chromatin duplication in the 3D nuclear space remain debated. I'll present our last efforts to understand the formation and organization of sister chromatids in the context of yeast using a combination of polymer simulations, data analysis and Hi-C experiments. In particular, we highlight the presence of characteristic “fountain” patterns around early origins of replication in Hi-C, signature of the colocalization of sister-forks and demonstrate a preferential asymetric cohesion between sister chromatids.