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Zooming in on the make-up of muscles

18 May 2021

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

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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