Bisexual Fruit Flies

Researchers at the University of Illinois at Chicago have turned straight fruit flies gay.


Gene makes fruit flies bisexual: study

December 10, 2007
BY JIM RITTER Health Reporter jritter@suntimes.com

A new study is providing insights into the genetics of homosexuality -- at least in fruit flies.

Researchers have discovered a gene involved in homosexual behavior in the tiny flies. They also found a way to turn homosexuality on and off with drugs.


Humans have a similar gene. But it's unclear what effect, if any, the gene has on homosexual behavior in people, said biologist David Featherstone of the University of Illinois at Chicago.

Featherstone and colleagues described their findings in the journal Nature Neuroscience.

After a century of study on fruit flies, researchers have accumulated a vast storehouse of genetic knowledge. UIC researchers were using fruit flies to study muscular dystrophy when they discovered a gene they call "gender blind," or GB.

Flies with a mutated form of the GB gene are bisexual. It appears they're unable to distinguish chemical smells, called pheromones, that tell whether other flies are male or female.

"The GB mutant males treated other males exactly the same way normal male flies would treat a female," Featherstone said. "They even attempted copulation."

The GB mutation appears to strengthen nerve cell junctions called synapses. This causes flies to over-react to pheromones. As a result, they "broaden their horizons and go for both males and females," Featherstone said.

Researchers tested this idea by adding a drug to the flies' apple juice. The drug weakened the synapses. So within a few hours, flies with the GB mutation stopped engaging in homosexual behavior.

Conversely, researchers gave heterosexual male flies a drug that strengthened their synapses. Sure enough, these male flies soon were courting males as well as females.

"It was amazing," Featherstone said. "I never thought we'd be able to do that sort of thing, because sexual orientation is supposed to be hard-wired. This fundamentally changes how we think about this behavior."