Changes of higher order chromatin arrangements during major genome activation in bovine preimplantation embryos.
Gene-dense chromosome territories (CTs) are typically located more interior, gene-poor CTs more peripheral in mammalian cell nuclei. Here, we show that this gene-density correlated CT positioning holds for the most gene-rich and gene-poor bovine chromosomes 19 and 20, respectively, in bovine fibroblast and lymphocyte nuclei. In order to determine the period at which this non-random CT order is established during development, we performed fluorescence in situ hybridization, on three-dimensionally preserved bovine preimplantation embryos generated by in vitro fertilization and investigated the distribution of BTA 19 and 20 CTs. Radial arrangements of CTs 19 and 20 were the same up to the 8-cell stage. At the 10- to 16-cell stage, however, a significant difference became apparent with CTs 19 localized more internally and CTs 20 more peripherally. Since major genome activation in bovine embryos occurs at the 8- to 16-cell stage, our findings demonstrate a temporal correlation between transcriptional activation and a major rearrangement of chromatin topography in blastomere nuclei.
Koehler
Daniela
D
Division of Anthropology and Human Genetics, Biocenter, LMU Munich, Grosshadernerstr. 2, D-82152 Martinsried, Germany.
Zakhartchenko
Valeri
V
Froenicke
Lutz
L
Stone
Gary
G
Stanyon
Roscoe
R
Wolf
Eckhard
E
Cremer
Thomas
T
Brero
Alessandro
A
D000818:Animals; D001755:Blastocyst / Q000378:metabolism* / Q000648:ultrastructure; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism* / Q000648:ultrastructure; D002875:Chromosomes / Q000378:metabolism* / Q000648:ultrastructure; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D008214:Lymphocytes / Q000378:metabolism / Q000648:ultrastructure
D002843:Chromatin