Spatio-temporal dynamics of repetitive sequences in preimplantation rabbit embryos
Résumé
Nowadays, a critical question in the epigenetic field is how chromatin is organized within the cell nucleus and how chromatin architecture affects and even regulates gene expression. In this study we hypothesize that nuclear structure could be involved in the control of gene expression during early rabbit embryonic development. We focused on pericentric/centric heterochromatin, a peculiar region within nuclei, known to form higher-order chromatin structures. We therefore performed FISH (Fluorescent In Situ Hybridization) and immuno-FISH to evaluate the relative localization of two types of repetitive satellite sequences “Rsat” in preimplantation rabbit embryos, especially at the time of MET (Maternal to Embryonic-Transition). We found that pericentric heterochromatin dynamic changes during rabbit embryogenesis. After fertilization, the repetitive sequences are first dispersed within the nuclei of early stage embryos. Foci only progressively appeared in embryonic nuclei by the 8/16 cell stage, suggesting that dramatic changes of chromatin structure are associated to the progressive onset of transcription during MET.