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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Genet. | doi: 10.3389/fgene.2019.00512

Methylome dynamics of bovine gametes and in vivo early embryos

 Jingyue Duan1,  Zongliang Jiang2, Fahad Alqahtani3,  Ion Mandoiu3, Dong Hong4, Xinbao Zheng4,  Sadie L. Marjani5, Jingbo Chen4* and Xiuchun Tian1*
  • 1Department of Animal Science, University of Connecticut, United States
  • 2School of Animal Science, AgCenter, Louisiana State University, United States
  • 3Department of Computer Science, University of Connecticut, United States
  • 4Institute of Animal Science, Xinjiang Academy of Animal Science, China
  • 5Department of Biology, Central Connecticut State University, United States

DNA methylation undergoes drastic fluctuation during early mammalian embryogenesis. The dynamics of global DNA methylation in bovine embryos, however, have mostly been studied by immunostaining. We adopted the whole genome bisulfite sequencing (WGBS) method to characterize stage-specific genome-wide DNA methylation in bovine sperm, immature oocytes, oocytes matured in vivo and in vitro, as well as in vivo developed single embryos at the 2-, 4-, 8- and 16-cell stages. We found that the major wave of genome-wide DNA demethylation was complete by the 8-cell stage when de novo methylation became prominent. Sperm and oocytes were differentially methylated in numerous regions (DMRs), which were primarily intergenic, suggesting that these noncoding regions may play important roles in gamete specification. DMRs were also identified between in vivo and in vitro matured oocytes, suggesting environmental effects on epigenetic modifications. In addition, virtually no (less than 1.5%) DNA methylation was found in mitochondrial DNA. Finally, by using RNA-seq data generated from embryos at the same developmental stages, we revealed a weak inverse correlation between gene expression and promoter methylation. This comprehensive analysis provides insight into the critical features of the bovine embryo methylome, and serves as an important reference for embryos produced in vitro, such as by in vitro fertilization and cloning. Lastly, these data can also provide a model for the epigenetic dynamics in human early embryos.

Keywords: DNA Methylation, Gametes, WGBS, bovine, early embryo developemnt, Methylome profile

Received: 20 Mar 2019; Accepted: 10 May 2019.

Edited by:

Albert Jeltsch, University of Stuttgart, Germany

Reviewed by:

Hehuang Xie, Virginia Tech, United States
Alan M. O'Doherty, University College Dublin, Ireland  

Copyright: © 2019 Duan, Jiang, Alqahtani, Mandoiu, Hong, Zheng, Marjani, Chen and Tian. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Jingbo Chen, Xinjiang Academy of Animal Science, Institute of Animal Science, Ürümqi, Xinjiang Uyghur Region, China, chenjb126@126.com
Prof. Xiuchun Tian, University of Connecticut, Department of Animal Science, Mansfield, 06269, Connecticut, United States, xiuchun.tian@uconn.edu