Remote control isn't just for gadgets anymore. Researchers have now genetically engineered flies that can be ordered to leap, fly, and walk at the flash of a laser.
Scientists have traditionally studied the neural basis of behavior in live animals by using techniques such as stimulating neurons with electrodes. But these methods are invasive and tend to hamper or immobilize the animal. Plus, the electrodes are unable to reach networks of cells dispersed throughout the nervous system.
To get around this problem, neurobiologists Susana Lima and Gero Miesenböck of the Yale University School of Medicine in New Haven, Connecticut, inserted a gene that codes for a rat ion channel into Drosophila fruit flies. This particular ion channel transmits electrical impulses by allowing charged particles to cross cell membranes in the presence of ATP, the ubiquitous energy-carrying molecule. The researchers then injected the flies with ATP inactivated by its enclosure within another molecule. When hit with a burst from an ultraviolet laser, the ATP broke free, activating the rat ion channels and causing the fly's neurons to fire, the researchers report today in Cell.
In flies made to express the rat ion channel in their dopaminergic neurons, which influence the fly's walking, the laser caused sedentary flies to become hyperactive. If the ion channel were expressed in the giant fiber neurons, which control reflexes for escape, the flies could be made to leap about, buzz their wings, and fly. The method could be used to study a plethora of other behaviors, including courtship, mating, and feeding, the researchers say.
"The implications [of this work] are huge" for understanding how neurons and behavior work together, says neurobiologist Paul Salvaterra of the City of Hope's Beckman Research Institute in Duarte, California. "I am sure many studies will soon take advantage of this new technology."