This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study from EMBL Rome shows how embryos precisely coordinate gene activity during early development. The research is published in the journal Science Advances.
Shortly after fertilization, the newly formed embryo faces a remarkable challenge: it must switch from relying on molecules supplied by the mother to using its own genome. This process, known as embryonic genome activation (EGA), is one of the earliest and most important steps in development. EGA has been studied in detail in model systems such as the fruit fly and zebrafish.
However, data from mammals are relatively scarce. This is because mammalian embryos are difficult to access and hard to analyze regularly over time. Researchers in Ana Boskovic's group at EMBL Rome developed a precision in vitro fertilization (IVF) protocol in mice to precisely control when fertilization occurs.
They combined this technique with the analysis of gene activity in individual embryos at several time points during early development. This allowed them to obtain an unprecedented high-resolution view of embryonic genome activation. The work shows that even embryos that look identical can contain vastly different RNA landscapes, depending on slight differences in their developmental timing (time after fertilization).
Moreover, the study provides a comprehensive resource detailing the gradual gene expression changes that occur during embryonic genome activation. The team followed the embryos over a nine-hour period and found extensive changes in their gene activity. As the embryo's own genome became increasingly active, RNA inherited from the mother was gradually depleted.
This switch from maternal provisions to embryonically derived molecules was marked by an increase in activation of genes involved in processes such as RNA production, protein synthesis and ribosome construction. At the same time, the early embryo undergoes widespread changes to its epigenome—the system that helps control which genes are switched on or off and modulates their expression levels. These include resetting chemical tags on proteins called histones, as well as removing and rebuilding DNA methylation patterns, contributing to gene regulation during EGA.
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