Rockefeller University and University of Tokyo researchers said its been believed when molecules in the air travel up an insect's nose, they latch onto a large protein on the surface of the cell and set off a chain of steps to open a molecular gate, signaling an odor is present.

"It's that way in the nematode, it's that way in mammals, it's that way in every known vertebrate," said study co-author Leslie Vosshall of Rockefeller University. "So it's actually unreasonable to think that insects use a different strategy to detect odors. But here, we show that insects have gotten rid of all this stuff in the middle and activate the 'gate' directly."

When molecules bind to the odor-sensitive ion channel, the protein opens, allowing ions to surge into the cell, the researchers said. Closed, it prohibits the activity that sends a signal to the brain that an odor is present.

The study that included the University of Tokyo appears in the advance online issue of the journal Nature.