Seeking to explain this unexpected behavior, the researchers compared Tas1r2 genes from various species that can and cannot taste aspartame. They were surprised to find no consistent differences between aspartame tasters and nontasters.
However, the genetic analysis did reveal that the red panda's sweet receptor has a unique structure that is different from any of the other species examined.
"This may explain why the red panda is able to taste artificial sweeteners," said Li, who is the paper's lead author. "What we don't know is why this particular animal has this unusual ability. Perhaps the red panda's unique sweet receptor evolved to allow this animal to detect some compound in its natural food that has a similar structure to these sweeteners."
The findings suggest that the receptor mechanisms for sweet taste are more complex than previously suspected. "This is the essence of molecular science," remarked Brand, "Asking a behavioral question and getting a molecular answer."
Future studies will explore how protein structure of taste receptor genes predicts stimulus binding and ultimately provide insight into how variations in taste receptor genes affect taste perception, food choice and nutritional status.
Taste tests for the red panda and other animals in the study were conducted at two zoos in Switzerland by Dieter Glaser, PhD, from the University of Zurich. Also contributing to the study were Monell scientists Gary Beauchamp and Weihua Li, along with Warren Johnson and Stephen O'Brien from the National Cancer Institute.
|Contact: Leslie Stein|
Monell Chemical Senses Center