[S]cientists have genetically modified fruit flies to jump or beat their wings when flashed with lasers.
The remote control setup — developed by Miesenbock and Susana Lima, both from Yale University School of Medicine — can be broken down into three components: a lock, a key and a trigger.
The lock is an ion channel — a kind of protein that allows charged particles to pass through a cell membrane. The researchers genetically altered particular neurons to have an ion channel not normally found in fruit flies.
The key is a molecule called adenosine triphosphate, or ATP. By binding to the ion channel, ATP makes the neuron fire. Typically, ATP is a form of fuel, or "energy currency," inside cells, "but there is very little of it flowing in between cells," Miesenbock said. So the scientists had to inject ATP into the fly brains.
To regulate the firing of the altered neurons, the researchers isolated the injected ATP in a molecular cage that breaks open when struck with an ultraviolet laser beam.
Lima and Miesenbock placed their ion channel lock in the giant fiber system, a small set of nerve cells that controls the fruit fly’s escape movements — like jumping and wing flapping.
When flashed with a 200-millisecond laser trigger, flies outfitted with locks and keys responded between 60 and 80 percent of the time with the expected escape behavior. And this was not because the laser scared the flies. In fact, blind flies reacted in the same way. The laser light penetrates the flies’ cuticle, or "skin," to free the caged ATP.
Friday, April 08, 2005
Fly brains manipulated by remote control