DNA Methylation Pattern in Pronuclear-Stage Mouse Embryos:Effect of Oocyte Vitrification

作     者：Ying Liang Xiangwei Fu Junjie Li Dianshuai Yuan Shien Zhu 

作者机构：Key Laboratory of Animal Genetics Breeding and Reproduction Ministry of Agriculture and National Engineering Laboratory for Animal Breeding College of Animal Science and Technology China Agricultural University Beijing 100193 China 

出 版 物：《Journal of Animal Science and Biotechnology》 (畜牧与生物技术杂志（英文版）)

年 卷 期：2011年第2卷第4期

页      面：192-198页

学科分类：0905[农学-畜牧学] 08[工学] 09[农学] 090501[农学-动物遗传育种与繁殖] 0836[工学-生物工程] 

主　　题：DNA methylation mouse oocyte open-pulled straw vitrification pronucleus 

摘      要：This study was conducted to investi- gate the pattern of DNA methylation in pronuclearstage mouse embryos derived from vitrified-warmed oocytes. Mouse oocytes at metaphase II （MII） stage of meiosis were allocated randomly into three groups： 1） untreated （control）; 2 ） exposed to vitrification solution without being plunged into liquid nitrogen （toxicity）; and 3 ） vitrified by open-pulled straw （OPS） method （vitrification）. Oocytes were fertilized in vitro （IVF）. The level of DNA methylation was examined at 8 hpf （hours post-fertilization） by immunofluorescence using an anti-5-methylcytosine （5-MeC） monoclonal antibody and fluorescein isothiocyanate （FITC）-conjugated goat anti-mouse IgG. After IVF, rates of 2-cell embryos （ 51.39% ） and blastocysts （35.82%） for vitrified-warmed oocytes were lower （P〈0.01） than that for control （70.83%, 47.82% ） or vitrification solution treated （64.80%, 46.29% ） oocytes. At 8 hpf, there were more （P 〈 0.05） pronuclear-stage oocytes in which syngamy of pronuclei had not occurred in the vitrifica- tion group. In addition, 5-MeC fluorescent intensities for the female pronucleus and zygote were lower in the vitrification group （P 〈0.01 ） compared to pronuclear-stage embryos in the control and toxicity groups. In conclusion, oocyte vitrification causes a reduction in global genomic methylation in the female pronucleus and zygote, resulting in delayed fusion of pronuclei and compromising the developmental potential of mouse zygotes and embryos.