Sensing calories without taste

Scientist have successfully engineered rodents and fruit flys so that they aren't able to sense any nutrients which includes sugar. At the beginning of the study the fruit flys won't show any preference between sugar water or regular water. But after 15 hours of no food they prefer to choose the water with sugar.. Although they cant taste the life-sustaining calories. In one paper published they have  found that a certain receptor in fruit fly brain neurons acts as a fructose sensor.

Interesting!

http://www.the-scientist.com/?articles.view/articleNo/35077/title/Sensing-Calories-Without-Taste/