AA FOR FRUIT FLIES?
Perhaps a more appropriate name for the fruit fly might be the bar fly. Apparently the annoying pests enjoy a little liquor when they dine. And according to scientists studying Drosophila melanogaster (AKA the fruit fly), once the flies get a taste, they’re hooked. According to a study appearing in the online version of current biology in December, the flies show evidence of alcohol addiction, including drinking despite dangerous consequences. Studying a model of alcoholism in a simple organism like the fruit fly may lead to a better understanding of the disease in humans. Although previous studies found that alcohol has profound physiological effects on fruit flies, the new study is one of the first to offer flies the choice to drink. Anita Devineni and Ulrike Heberlein, both of the University of California, San Francisco, devised a fly-sized drinking device akin to the water bottles in hamster cages. Flies held inside vials could sip from thin tubes holding either liquid food spiked with 15 percent ethanol or plain liquid food. The researchers measured the descent of the liquids inside each tube to get a readout of which food the flies preferred. Flies consumed the liquor-laden food much faster than the straight food, the researchers found. This alcohol preference became stronger over five days as the insects adjusted to the drinking. When Devineni and Heberlein varied the amount of alcohol in the food, they found that flies that had been drinking for only one to two days didn’t seem to like the strong stuff, but regular drinkers that had been consuming alcohol for four to five days did. These flies drank food that contained up to 25 percent alcohol. Quite a high tolerance! As the flies drank alcohol, Devineni observed drunken behavior such as hyperactivity and loss of coordination. The researchers were unable to get exact measurements of alcohol levels in individual flies because they’re so small. “I think they are intoxicated, but it’s unclear to what degree,” Devineni said.
Fruit flies accustomed to alcohol continued to drink despite potential harm, the team found. When the researchers laced the alcohol-food mix with small amounts of the toxic chemical quinine, those flies continued to drink, even though fruit flies normally avoid the chemical. In another test, flies were allowed to drink freely for five days, then were deprived of alcohol for either one or three days. After the dry period, the flies immediately returned to peak levels of drinking, a hallmark of relapse. This fruit fly model of alcoholism may provide researchers with new experimental options, such as the ability to easily track down genes that are involved with the disease. Some of these genes may be the same as those in humans. “It’s known that there’s a strong genetic component to alcoholism,” Devineni says. “Flies are one of the best model systems for genetics,” she adds. So the next time you see a fruit fly in your drink, check how much of it is gone. He might owe you a new one.