Pull Yourself Together

If we could zoom in on our tensing muscles, we’d see bundles of thick and thin filaments pulling together. Speedy chemical reactions form tiny ‘cross bridges’ between them and, a bit like a climbers finding a grip, one filament pulls itself along the other. This happens all the way down a muscle fibre – repeating regions or sarcomeres shorten and the overall muscle contracts, helping us lift the heavy shopping, or climb a wall. Here researchers use electron cryotomography to blast mouse muscle with beams of electrons, mapping out contours from tiny deflections made in each electron’s path. A computer simulation lifts the image into 3D, highlighting separate filaments in rainbows colours. At this level of detail, researchers can zoom in on the molecular makeup of sarcomeres and their cross bridges (seen here as sticky-out branches on the filaments), giving insight into muscle biology and eventually injury and disease.

Written by John Ankers

John Ankers

Writer

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 Zhexin Wang and Michael Grange, and colleagues
• Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Cell, March 2021