title: Phosphorylated histone H2A.x in porcine embryos produced by IVF and somatic cell nuclear transfer.
abstract: Phosphorylated histone H2A.x (H2AX139ph) is a key factor for the repair of DNA double-strand breaks (DSBs) and the presence of H2AX139ph foci indicates the sites of DSBs. In this study, we characterized the presence of H2AX139ph during in vitro development of porcine embryos produced by IVF and somatic cell nuclear transfer (SCNT). Pronuclear stage embryos produced by IVF had, on average, 9.2 H2AX139ph foci per pronucleus. The number of H2AX139ph foci was higher in the 2-cell-stage embryos than in the 4-cell-stage embryos fixed at 48 h post-fertilization. The percentage of H2AX139ph-positive nuclei was higher in SCNT embryos that were activated with ionomycin (ION) alone than in those activated with ION and strontium chloride (ION+Sr(2+)). A negative correlation was found between the percentage of H2AX139ph-positive cells and the total number of cells per embryo in day 7 blastocysts produced by IVF or SCNT. Based on the detection of H2AX139ph foci, the findings of this study indicate that DSBs occur in a high proportion of porcine embryos produced by either IVF or SCNT; fast-cleaving embryos have fewer DSBs than slow-cleaving embryos; the oocyte activation protocol can affect DNA integrity in SCNT embryos; and better-quality blastocysts have fewer DSBs. We propose that the presence of H2AX139ph foci can be a useful marker of embryo quality.
authors.affiliation: Department of Animal Science, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9.
authors.forename: Rodrigo C
authors.initials: RC
authors.lastname: Bohrer
authors.forename: Limei
authors.initials: L
authors.lastname: Che
authors.forename: Paulo B D
authors.initials: PB
authors.lastname: Gonçalves
authors.forename: Raj
authors.initials: R
authors.lastname: Duggavathi
authors.forename: Vilceu
authors.initials: V
authors.lastname: Bordignon
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D053903:DNA Breaks, Double-Stranded; D046149:Embryo Culture Techniques / Q000379:methods*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005307:Fertilization in Vitro; D005455:Fluorescent Antibody Technique; D006657:Histones / Q000378:metabolism*; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D013552:Swine
chemical_list: D006657:Histones