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Published January 20, 2005 | public
Journal Article Open

Molecular dynamics of cyclically contracting insect flight muscle in vivo


Flight in insects—which constitute the largest group of species in the animal kingdom—is powered by specialized muscles located within the thorax. In most insects each contraction is triggered not by a motor neuron spike but by mechanical stretch imposed by antagonistic muscles. Whereas 'stretch activation' and its reciprocal phenomenon 'shortening deactivation' are observed to varying extents in all striated muscles, both are particularly prominent in the indirect flight muscles of insects. Here we show changes in thick-filament structure and actin–myosin interactions in living, flying Drosophila with the use of synchrotron small-angle X-ray diffraction. To elicit stable flight behaviour and permit the capture of images at specific phases within the 5-ms wingbeat cycle, we tethered flies within a visual flight simulator. We recorded images of 340 µs duration every 625 µs to create an eight-frame diffraction movie, with each frame reflecting the instantaneous structure of the contractile apparatus. These time-resolved measurements of molecular-level structure provide new insight into the unique ability of insect flight muscle to generate elevated power at high frequency.

Additional Information

© 2005 Nature Publishing Group. Received 20 August; accepted 29 November 2004. We thank J. Costello for help with data analysis, J. Fockler for computer programming, and D. Swank, R. Tregear, M. K. Reedy and M. C. Reedy for helpful discussions. The research was supported by NIH. The APS is supported by the US Department of Energy. BioCAT is a NIH-supported Research Center.

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August 19, 2023
August 19, 2023