title: Early aberrations in chromatin dynamics in embryos produced under in vitro conditions.
abstract: In vitro production of porcine embryos by means of in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT) is limited by great inefficienciy. The present study investigated chromatin and nucleolar dynamics in porcine embryos developed in vivo (IV) and compared this physiological standard to that of embryos produced by IVF, parthenogenetic activation (PA), or SCNT. In contrast to IV embryos, chromatin spatial and temporal dynamics in PA, IVF, and SCNT embryos were altered; starting with aberrant chromatin-nuclear envelope interactions at the two-cell stage, delayed chromatin decondensation and nucleolar development at the four-cell stage, and ultimately culminating in failure of proper first lineage segregation at the blastocyst stage, demonstrated by poorly defined inner cell mass. Interestingly, in vitro produced (IVP) embryos also lacked a heterochromatin halo around nucleolar precursors, indicating imperfections in global chromatin remodeling after fertilization/activation. Porcine IV-produced zygotes and embryos display a well-synchronized pattern of chromatin dynamics compatible with genome activation and regular nucleolar formation at the four-cell stage. Production of porcine embryos under in vitro conditions by IVF, PA, or SCNT is associated with altered chromatin remodeling, delayed nucleolar formation, and poorly defined lineage segregation at the blastocyst stage, which in turn may impair their developmental capacity.
authors.affiliation: Department of Basic Animal and Veterinary Sciences, Faculty of Life Sciences, University of Copenhagen, Denmark.
authors.forename: Rahul S
authors.initials: RS
authors.lastname: Deshmukh
authors.forename: Olga
authors.initials: O
authors.lastname: Østrup
authors.forename: Frantisek
authors.initials: F
authors.lastname: Strejcek
authors.forename: Morten
authors.initials: M
authors.lastname: Vejlsted
authors.forename: Andrea
authors.initials: A
authors.lastname: Lucas-Hahn
authors.forename: Bjorn
authors.initials: B
authors.lastname: Petersen
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Henrik
authors.initials: H
authors.lastname: Callesen
authors.forename: Heiner
authors.initials: H
authors.lastname: Niemann
authors.forename: Poul
authors.initials: P
authors.lastname: Hyttel
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000648:ultrastructure; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D002869:Chromosome Aberrations / Q000196:embryology*; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000502:physiology; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000662:veterinary; D005865:Gestational Age; D007700:Kinetics; D053652:Nuclear Transfer Techniques; D010312:Parthenogenesis / Q000502:physiology; D013552:Swine / Q000196:embryology / Q000235:genetics; D013997:Time Factors
chemical_list: D002843:Chromatin