- Researchers find DNA replication in early embryos is different from mature cells, with a period of instability at the 4-cell stage that can lead to chromosomal errors.
- This finding could have significant implications for reproductive medicine, potentially leading to improved in vitro fertilization (IVF) techniques and strategies.
Researchers at the RIKEN Center for Biosystems Dynamics in Japan have made a discovery that challenges long-held beliefs about DNA replication.
Led by Ichiro Hiratani, their study published on August 28 in Nature reveals that DNA replication in early embryos is different from what we previously thought, showing a period of instability that can lead to errors in chromosome copying.
Since chromosomal abnormalities are linked to failed pregnancies and developmental disorders, this finding could influence reproductive medicine and potentially lead to better in vitro fertilization (IVF) techniques.
During embryogenesis, the fertilized egg divides multiple times, with each division copying the entire genome. By the third day, the embryo has 16 cells. RIKEN BDR researchers, using their single-cell genomics technique called scRepli-seq, studied DNA replication in early-stage mouse embryos. Their findings challenged previous assumptions about how DNA replication occurs in embryos.
“We found multiple specialized types of DNA replication during early mouse embryogenesis, which no one has seen before. In addition, we also found that at certain points, genomic DNA is temporarily unstable and chromosomal aberrations are elevated,” stated Ichiro Hiratani, Researcher, RIKEN Center for Biosystems Dynamics (BDR).
Researchers have discovered that DNA replication in early embryos doesn't follow the usual sequence seen in mature cells. In 1- and 2-cell embryos, DNA replicates uniformly, but by the 4-cell stage, it starts transitioning to the more ordered process seen later.
However, the replication fork, which copies DNA, moves much slower in these early stages. This slow movement at the 4-cell stage leads to a spike in chromosomal errors, which can cause miscarriages or developmental disorders like Down Syndrome.
Moreover, this research could help fertilization clinics develop better strategies to reduce chromosomal abnormalities in early embryos.
Edited by Harshajit Sarmah
