title: Architectural reorganization of the nuclei upon transfer into oocytes accompanies genome reprogramming.
abstract: The ability of cloned embryos to sustain full-term development depends on the ability of the recipient ooplasm to reprogram the donor cell genome. As the nuclear architecture has recently emerged as a key-factor in the regulation of gene expression, we questioned whether early embryos obtained from transfer of ES metaphasic chromosomes into mouse ooplasm would adopt the somatic or embryonic type of nuclear organization. We have particularly focused on the arrangement of chromosomal territories with respect to the nucleolar compartment, and the pericentric heterochromatin domains called chromocenters. We found that nuclear transfer triggers profound chromatin rearrangements including the dispersion of the donor cell chromocenters components. These rearrangements lead to a typical 1-cell pronuclear organization, namely a radial arrangement of the chromosome territories with centromeres attached to the nucleoli, which adopt the compact fibrillar structure of nucleolar precursor bodies (NPBs). Subsequently, during the second cycle, the cloned embryos undergo further reorganization with the establishment of new chromocenters, clustered in one part of the nucleus, as during normal embryogenesis. We could also establish that the adequate distribution of chromosomal territories at the pronuclear stage seems important for the development until blastocyst.
authors.affiliation: UMR 13-1198 Biologie du Développement, Institut National de Recherche Agronomique, Domaine de Vilvert, Jouy-en-Josas, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Martin
authors.forename: Vincent
authors.initials: V
authors.lastname: Brochard
authors.forename: Carole
authors.initials: C
authors.lastname: Migné
authors.forename: Daniele
authors.initials: D
authors.lastname: Zink
authors.forename: Pascale
authors.initials: P
authors.lastname: Debey
authors.forename: Nathalie
authors.initials: N
authors.lastname: Beaujean
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics* / Q000502:physiology*; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics; D033481:Chromosomes, Mammalian / Q000235:genetics; D003593:Cytoplasm / Q000235:genetics; D004622:Embryo, Mammalian / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D016678:Genome / Q000235:genetics*; D051379:Mice; D008854:Microscopy, Electron; D008938:Mitosis; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D002843:Chromatin