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🧬 A new study reveals that ancient viral DNA remnants, known as transposable elements, play a crucial role in early embryo development across several mammalian species. These elements, making up over half of our genomes, were once dismissed as insignificant, but researchers have discovered their reactivation in the first hours and days after fertilization is vital for cellular plasticity.The team developed a novel method to study the transcription of these ancient DNA sequences, creating a single-embryo atlas by comparing embryos from mouse, cow, pig, rabbit, and rhesus macaque. They found that even very old, supposedly extinct viral elements are re-expressed, with each species expressing distinct types of these elements.This conserved activation of transposable elements across species offers opportunities to manipulate cell fate, potentially directing stem cell differentiation by simultaneously influencing thousands of genes. The study highlights the importance of understanding the regulatory principles behind these elements. By gaining insights into how early-stage cells regulate ancient viral elements, researchers can better understand the mechanisms of cellular plasticity, with broad implications for health, disease, and cellular processes. The generated dataset from this study will also serve as a valuable resource for researchers in developmental and reproductive biology.📄 RESEARCH PAPER:Marlies E. Oomen et al., "An atlas of transcription initiation reveals regulatory principles of gene and transposable element expression in early mammalian development", Cell (2025).