title: Analysis of chromatin structure in mouse preimplantation embryos by fluorescent recovery after photobleaching.
abstract: Zygotes are totipotent cells that have the ability to differentiate into all cell types. It is believed that this ability is lost gradually and differentiation occurs along with the progression of preimplantation development. Here, we hypothesized that the loose chromatin structure is involved in the totipotency of one-cell stage embryos and that the change from loose to tight chromatin structure is associated with the loss of totipotency. To address this hypothesis, we investigated the mobility of eGFP-tagged histone H2B (eGFP-H2B), which is an index for the looseness of chromatin, during preimplantation development based on fluorescent recovery after photobleaching (FRAP) analysis. The highest mobility of eGFP-H2B was observed in pronuclei in 1-cell stage embryos and mobility gradually decreased during preimplantation development. The decrease in mobility between the 1- and 2-cell stages depended on DNA synthesis in 2-cell stage embryos. In nuclear transferred embryos, chromatin in the pseudopronuclei loosened to a level comparable to the pronuclei in 1-cell stage embryos. These results indicated that the mobility of eGFP-H2B is negatively correlated with the degree of differentiation of preimplantation embryos. Therefore, we suggest that highly loosened chromatin is involved in totipotency of 1-cell embryos and the loss of looseness is associated with differentiation during preimplantation development.
authors.affiliation: a Department of Integrated Biosciences , Graduate School of Frontier Sciences, The University of Tokyo , Kashiwa, Chiba , Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Ooga
authors.affiliation: a Department of Integrated Biosciences , Graduate School of Frontier Sciences, The University of Tokyo , Kashiwa, Chiba , Japan.|b Department of Biology of Reproduction , Institute of Animal Science , Prague , Czech Republic.
authors.forename: Helena
authors.initials: H
authors.lastname: Fulka
authors.affiliation: a Department of Integrated Biosciences , Graduate School of Frontier Sciences, The University of Tokyo , Kashiwa, Chiba , Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: a Department of Integrated Biosciences , Graduate School of Frontier Sciences, The University of Tokyo , Kashiwa, Chiba , Japan.
authors.forename: Masataka G
authors.initials: MG
authors.lastname: Suzuki
authors.affiliation: a Department of Integrated Biosciences , Graduate School of Frontier Sciences, The University of Tokyo , Kashiwa, Chiba , Japan.|b Department of Biology of Reproduction , Institute of Animal Science , Prague , Czech Republic.
authors.forename: Fugaku
authors.initials: F
authors.lastname: Aoki
mesh_terms: D000818:Animals; D001755:Blastocyst; D002843:Chromatin / Q000648:ultrastructure*; D004261:DNA Replication; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D053595:Embryonic Stem Cells / Q000166:cytology; D005260:Female; D036681:Fluorescence Recovery After Photobleaching; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D041681:NIH 3T3 Cells
chemical_list: D002843:Chromatin; D006657:Histones; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: Chromatin structure; FRAP; mouse embryo; preimplantation development; reprogramming