Separate Ways

Symmetry is everywhere in life. Yet in these cells inside an early zebrafish embryo, asymmetry heralds a vital step in development. Different patterns must emerge in the embryonic cells, early steps in defining tissues and organs, driven by the transcribing ('switching on') of their genes – known as the maternal-to-zygotic transition. In this video, researchers use different fluorescent sensors to watch the cells progressing through the cell cycle (purple), and the timing of a burst of zygotic transcription (green dots). They find that the timing of cell division and transcription is influenced by the cell’s location, creating different patterns of activity around the developing embryo. Investigating similar patterns in human embryos may answer some questions about this most sensitive stage of life.

Written by John Ankers

John Ankers

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A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video from work by Nikhil Mishra and colleagues
• Institute of Science and Technology Austria, Klosterneuburg, Austria
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Nature Physics, January 2026