Graduate students Yifeng Zhang (left) and Grace Zhao (right) discuss ongoing experiments with HHMI investigator Charles Zuker.
Photo: Barbara Ries
Toying with taste is a bit of a switch for Zuker, who is best known for his work on the visual systems of flies. "I'm a fly-eye kind of guy," he jokes. But his main interest is not so much in flies as in using their eyes as tools to understand sensory signaling. About three years ago, his research group decided to study a different sense—taste—and compare it with others, such as vision. They started out working with flies, but soon realized that isolating individual taste receptor cells from such tiny creatures was going to be mighty tricky.
"So that's when we made a leap and said, 'Let's try something bigger,'" Zuker recalls. "We tried cows, which was a hideous experience. Do you know how big a cow's tongue is? We're talking three and a half feet here!" Rats seemed a good compromise between the ridiculously tiny and the hideously huge.
"Right about the time that we started our rat work, we discovered the efforts that Nick Ryba and Mark Hoon were involved in at the National Institutes of Health, and we started a most wonderful, productive, collaborative joint effort," says Zuker.
From fly eyes to rat tongues, with a detour through the mouth of a cow—where will all this lead? Fittingly enough, it could be somewhere delicious. Understanding the molecular basis of sweet sensitivity could help researchers design more potent sweeteners for our sodas and snacks. And instead of simply masking unpleasant tastes—in medicines, for example—they might find ways of blocking bitterness altogether.
There may even be help for people whose problem is not blocking out awful tastes, but tasting anything at all. "As people get older," notes Zuker, "their enjoyment of food is often dramatically decreased"—probably because of diminished taste perception. By identifying and studying taste receptors and taste signaling pathways, researchers may be able to find molecules that act as modulators, enhancing the cell's capabilities.
