Actin Big

So much of biology happens at unimaginably small scales. One way to see this intricacy is to physically enlarge the body’s tiny cellular structures, swelling samples before looking down the microscope. But the process makes some structures, such as the fine actin filaments that make up cells’ internal scaffolding, hard to colour with stains typically used to highlight them. Researchers have developed a new molecule that sticks to these actin filaments and stays in place even after expansion. It carries a tag to which bright dyes can be added, giving strong and clear images of actin in everything from microbes to mouse retinas and dividing human cells (pictured, actin colour-coded at different depths of field, with a tight band of actin pinching the intersection of the dividing cells). This new approach could help clear up how changes in actin structure might drive diseases like cancer, immune disorders, and neurodegeneration.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Image from work by Olivier Mercey and Luc Reymond, and colleagues
• Department of Molecular and Cellular Biology, Faculty of Sciences, University of Geneva, Switzerland
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in bioRxiv, August 2025 (not peer reviewed)