Tiny fruit fly tongue holds clues to obesity

A fruit fly’s tiny tongue holds clues to our eating habits, potentially opening new ways to treat obesity, says a new study.

Drosophila, commonly called fruit flies and smaller than a grain of rice, are found worldwide with 1,500 species. The word is Latin for “dew loving”.

Paul Hardin, professor of biology from Texas A&M University, along with colleagues, examined the taste organs on Drosophila’s proboscis (tongue), which triggers the minute fruit fly’s desire to eat or not to eat.

They found that several factors, especially the creature’s internal daily clock, determine feeding behaviours - and these same taste sensitivities very likely apply to humans.

“The ‘clock’ that influences this decision to eat or not to eat is found inside the taste sensing cells, which send a signal to eat,” Hardin explains.

“Once this signal is sent, the brain then tells the fly to eat or not, but all of this seems to depend on the time of day. These clocks have a very direct link to its eating habits,” says Hardin.

Like most flies, they have a natural instinct to seek out food and they are always looking for something to eat, Hardin adds.

“These inner clocks control the sensitivity to food and also affect how much the flies eat. We found that the highest sensitivity to sugar is in the daytime, and far less at night.”

“But we found that if you eliminate these clocks, the flies will eat much more food. So these clocks seem to suppress the desire for food at certain times of day,” adds Hardin.

Hardin notes that there are obvious parallels that could be drawn comparing the desire for food by the fruit flies and the human desire for food. “It’s long been established that as humans, we have clocks, too,” he adds.

“If clocks in our taste-sensing cells also control when and how much we eat, it could greatly impact weight gain.” he said.

Obesity is one of the major threats to health worldwide, especially in the US, where the number of obese people has skyrocketed in recent years.

Their work was published in the latest issue of Current Biology.