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CORRECTED-Why cats will never live the sweet life

July 26, 2005

In WASHINGTON story of July 25 headlined “Why cats will
never live the sweet life,” please read in fourth paragraph …
Xia Li, a molecular geneticist at the Monell Chemical Senses
Center, a nonprofit research institute in Philadelphia, who
helped lead the study … instead of … Xia Li, a molecular
geneticist at Cornell University in New York, who helped lead
the study …

WASHINGTON (Reuters) – Cats may like ice cream, but it is
not the sugary taste that appeals to them because they are
genetically unable to taste sweet flavors, researchers reported
on Monday.

Domestic cats and big cats alike have a slightly different
version of the sweet receptor gene than other mammals, the
British and U.S. scientists found.

Any cat owner knows that cats have individual preferences,
but cats will turn their noses up at sugary treats that do not
contain some other ingredient such as butter or gelatin.

“One possible explanation for this behavior is that felines
are unable to detect sweet-tasting compounds like sugars and
high intensity sweeteners because their sweet taste receptor is
defective,” said Xia Li, a molecular geneticist at the Monell
Chemical Senses Center, a nonprofit research institute in
Philadelphia, who helped lead the study.

“An obvious place to look, therefore, is at the genes
coding for the sweet-taste receptor.”

So they did. Mammals taste sweet flavors via a receptor, a
kind of molecular doorway, called T1R on their taste bud cells.
It has two subunits, known as T1R2 and T1R3. Each is coded for
by a separate gene.

Writing in the online journal Public Library of Science
Genetics, Li and colleagues said they found a change in the
gene encoding the T1R2 protein in domestic cats, tigers and
cheetahs.

“Other than this sweet blindness, the cat’s sense of taste
is normal,” the researchers wrote in their report.

“The non-functional sweet receptor provides a molecular
explanation for why cats have no avidity for sweets,” said
Joseph Brand, a biophysicist at Cornell who worked on the
study.

“Looking beyond this elegant explanation, one can
contemplate the importance that this molecular change had on
the evolution of the cat’s carnivorous behavior,” Brand added
in a statement.

“What we still don’t know is — which came first:
carnivorous behavior or the loss of the T1R2 protein? With
regard to the gene, is this a case of use it or lose it?”

Many animals in the carnivore family like sweet things,
including bears, dogs, raccoons and others.

“I say jokingly, no wonder cats are cranky — not only do
they have to hunt for their food, but they also can’t enjoy a
sweet dessert,” Brand said.




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