"The taste world of every species, and even every individual, is unique, defined in part by the structure of their taste receptors," said Li. "We need to know more about these differences and how they influence our diet."
In the study, published online in the Journal of Heredity, preferences for six natural sugars and six artificial sweeteners were tested in a zoo setting. For each sweet molecule, the animal was given access to both the sweet solution and water for 24 hours. The animal was said to prefer the sweet solution when it drank much more sweet fluid than water.
DNA samples from each species were used to examine the structure of the sweet receptor gene Tas1r2, which codes for the T1R2 sweet taste receptor. T1R2 is one of two taste receptors that join together to recognize sweetness.
The sweet taste receptors contain binding sites for a variety of natural sugars and artificial sweeteners. However, species vary regarding which sites they possess, due to subtle differences in receptor structure.
As expected from the previous findings, the lion did not prefer any of the sweet solutions. This could be explained by its defective Tas1r2 gene, which prevents the lion from expressing a functional sweet taste receptor. With no sweet receptor, the lion is unable to detect or prefer sweet-tasting compounds.
Each of the remaining species preferred at least some of the natural sugars. Consistent with having a functional sweet receptor, Tas1r2 genes from these species did not show the defect found in lion and other cats.
Because only primates were believed to be able to taste aspartame, the researchers predicted that none of the Carnivore species tested would show a preference for the artificial sweeteners.
This indeed was the case for five of
|Contact: Leslie Stein|
Monell Chemical Senses Center