title: Global DNA methylation and related mRNA profiles in sheep oocytes and early embryos derived from pre-pubertal and adult donors.
abstract: The developmental capacity of in vitro-matured oocytes and in vitro-fertilized embryos from pre-pubertal sheep is less than that of adult counterparts, and epigenetic mechanisms are thought to be involved. In the present study, germinal vesicle stage oocytes were collected by follicular aspiration from superovulated 4-week-old lambs and 2.5-year-old ewes. There were evaluations of the developmental potential of oocytes and embryos by in vitro culture and fertilization, global DNA methylation and hydroxymethylation patterns by immunofluorescence staining, and relative abundance of enzyme mRNA by quantitative real-time polymerase chain reaction analysis in pre-pubertal and adult sheep donors. The results showed that the rates of maturation and cleavage of oocytes as well as pregnancy and lambing rates from the transfer of 2-cell embryos collected from lambs were less than those from adults (P<0.05). The global DNA methylation and hydroxymethylation and relative abundance of Dnmt1, Dnmt3a, and Tet3 mRNA were less at all stages of oocytes, zygotes, and two-cell embryos from lambs compared with those from adults (P<0.05) with no difference in relative abundance of Dnmt3b mRNA. Thus, younger donor age was associated with disturbed DNA methylation processes due to insufficient methyltransferases during gametogenesis and early embryonic development, and this may be responsible for the lesser developmental potential of oocytes and early developing embryos when oocytes are collected from lambs.
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin 130102, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Animal Husbandry and Veterinary Research Institute of Tianjin, Tianjin 300412, China.
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Animal Husbandry and Veterinary Research Institute of Tianjin, Tianjin 300412, China.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin 130102, P.R. China.
authors.forename: Rongzhen
authors.initials: R
authors.lastname: Zhong
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin 130102, P.R. China. Electronic address: zhoudaowei@iga.ac.cn.
authors.forename: Daowei
authors.initials: D
authors.lastname: Zhou
mesh_terms: D000818:Animals; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism; D046149:Embryo Culture Techniques; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary; D009865:Oocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012741:Sexual Maturation; D012756:Sheep / Q000196:embryology*; D059467:Transcriptome
chemical_list: D012333:RNA, Messenger; D049308:Dioxygenases; D004248:DNA (Cytosine-5-)-Methyltransferases
keywords: Embryo; Methylation; Oocyte; Puberty; Sheep