Want Big Muscles?

From a body-builder’s bulging bicep to the tiny flight muscles that keep a fruit fly’s wings beating, muscles are all made from bundles of long fibres divided into short, repeated segments called sarcomeres. When an animal makes a move, interlocking molecules within the sarcomere move past each other and cause the muscle to contract. These images show flight muscle fibres from six fruit flies, each with a different genetic change affecting a structure called the Z-disc (yellow), which marks the end of each sarcomere. Changes in a gene called Zasp affect the size of the Z-disc, in turn affecting the diameter of the fibre and altering the overall size and function of the muscle. Zasp is also involved in setting sarcomere size in the muscles of other animals, including humans. Some of these genetic changes mimic the effects seen in some types of muscle disease (myopathies), pointing towards future treatments.

Written by Kat Arney

Kat Arney

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Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image from work by Nicanor González-Morales and colleagues
• Department of Biology, McGill University, Montreal, Canada
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in eLife, November 2019