Red pandas reveal an unexpected (artificial) s...( PHILADELPHIA (April 15 2009) -- Rese...)

PHILADELPHIA (April 15, 2009) -- Researchers from the Monell Center report that the red panda is the first non-primate mammal to display a liking for the artificial sweetener aspartame. This unexpected affinity for an artificial sweetener may reflect structural variation in the red panda's sweet taste receptor.

The findings may shed light on how taste preferences and diet choice are shaped by molecular differences in taste receptors.

"The red panda's unique taste receptor gives us a tool to broaden our understanding of how we detect sweet taste," said the paper's senior author, Joseph G. Brand, PhD, a biophysicist at Monell. "Greater insight into why we like artificial sweeteners could eventually lead to the development of more acceptable sugar substitutes, potentially benefiting diabetics and other individuals on sugar-restricted diets."

Many species like sweet-tasting foods, but there are some exceptions. In an earlier study, Brand and Monell comparative geneticist Xia Li, PhD, reported that cats both domestic and wild can not taste sweets due to a defect in one of the genes that codes for the sweet taste receptor.

The current research extended those findings by relating sweet preferences to genetic analyses of sweet receptor structure in six related species. Like the cat, each of the species tested -- red panda, ferret, genet, meerkat, mongoose, and lion -- belongs to the Order Carnivora.

The species, although closely related, vary widely with regard to the types of foods they eat. For example, lions, like other cats, are obligate carnivores, meaning that they eat almost exclusively meat. Meerkrats are mainly insectivores, while red pandas are primarily herbivores that almost exclusively eat bamboo leaves and shoots.

By studying the structure and function of the sweet receptor gene across species and how this relates to differences in taste preferences and diet selection, the researchers see
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