A ground-breaking new scanning technique has allowed scientists to film the insides of a live, flying insect, capturing the first-ever high-speed 3D images of the flight muscles of flies.
Researchers from Oxford University, Imperial College and the Paul Scherrer Institute used a particle accelerator to capture the images, which could one day lead to the development of micro medical devices.
The scientists developed the technique in order to study the blowfly’s complicated joint system.
"The insect is very fast and very small, with wings that beat 150 times a second," said Oxford University professor Graham Taylor, a member of the research team. "Each one of those wing beats is controlled by some tiny muscles, some of which are as thin as a human hair. So this is really an enormous technical challenge to understand this, and a particularly challenging target for understanding biological systems.”
Watch related video:
Writing in PLOS Biology, Taylor says he and his colleagues detail the fly’s mechanics, particularly its steering muscles, that make up just 3 percent of its total flight muscles yet control the output of the much larger power muscles.
“And so the flies overcome this problem by way of a very complex system which is all based inside the fly. The problem with looking inside something is that visible light doesn’t penetrate into it. And, so what we need to use is x-rays, just as you would use to look at a bone fracture.”
But because the fly's wings beat so rapidly, the team turned to very fast imaging, which began, Taylor says, in a particle accelerator called a cyclotron.
"And we put the flies into a powerful beam of x-rays and we spin them around very rapidly. As the flies are spinning around you are able to capture radiographs from different viewing angles and by putting those together, as it's beating its wings, you can reconstruct in three dimensions how the flight motor looks at all of the different stages of the wing beat.”
Taylor says they saw in vivid detail, the fly's mechanics.
“The power muscles, rather than driving the wings directly, what they do is actually vibrate up and down the body, and those vibrations are communicated through a complicated hinge into the wings themselves. What the muscles that control the wing beat are doing, and this is what we’ve been looking at, is to just tweak the output at the wing hinge to which they are attached directly, and thereby change the shape of the wing beat that results.”
That hinge action, Taylor says, compares to what happens to your calf muscles when you walk down a steep hill.
"That pull in your calf muscles is because they’re taking up the energy that you are gaining, the kinetic energy as you descend down the slope. The fly is doing something very similar, absorbing that energy and diverting it into a different muscle.”
Taylor expects the technique devised for these observations will be used to track other small living organisms while also making its way into new micro-medical devices.