How The Fly Flies

Max Planck scientists discover gene switch responsible for flight muscle formation
Flies are real flight artists, although they only have small wings compared to their body size. Scientists at the Max Planck Institute of Biochemistry in Martinsried near Munich, Germany, recently identified the genetic switch that regulates the formation of flight muscles. “The gene spalt is essential for the generation of the ultrafast super muscles,” emphasizes Frank Schnorrer, head of the research group “Muscle Dynamics”. “Without spalt, the fly builds only normal leg muscles instead of flight muscles.” The scientists’ results have now been published in Nature.

In order to fly efficiently, flies have to flap their small wings very fast. This causes the familiar buzzing and humming of the small beasts. The fruit fly Drosophila melanogaster moves her wings at a frequency of 200 hertz – that means its flight muscles contract and relax 200 times per second. “In contrast, a hundred meters sprinter who moves his legs only a few times per second moves like a snail,” Frank Schnorrer describes. How can the fruit fly flap its wings at such a high frequency?

Muscles control all body movements, including the wing oscillations. However, flight muscles are unique. Their contractions are not only regulated by nerve impulses as usual, but additionally triggered by tension. Every fly has two categories of flight muscles which enable the wing oscillations: One type moves the wings down and, at the same time, stretches the other type which induces its contraction. Such, the wings are pulled up again and stable wing oscillations begin.

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