In a research published online this Monday by the journal Nature Neuroscience, scientists have succeeded to make fruit flies change their sexual orientation from homosexual to straight and back within hours.

While conducting a study on fruit flies about muscular dystrophy, researchers from the University of Illinois at Chicago discovered a gene they called “gender blind” gene, or GB. This gene, in a mutated form, made fruit flies to not distinguish chemical smells, called pheromones that can tell if other flies are male of female. These mutated GB male flies were engaging in courtship no matter that the other fly was male or female.

UIC researchers discovered that GB gene transports the neurotransmitter glutamate to brain cells and if they alter the levels of glutamate it changes the strength of nerve cell conjunctions, called synapses.

The biologist David Featherstone of the University of Illinois at Chicago said that he and his colleagues “reasoned that GB mutants might show homosexual behavior because their synapses were altered in some way." and because of that "homosexual courtship might be sort of an 'overreaction' to sexual stimuli."

It seemed that GB mutation strengthens synapses and because of that the flies over-react to pheromones, being no longer able to distinguish male pheromones as repulsive.

Researchers tested this idea by adding a drug that weakened the synapses to the flies’ apple jus. Within a few hours, flies with GB mutation stopped engaging in homosexual behavior. All the same, researchers gave heterosexual a drug that strengthened their synapses and in a few hours they began to court males as well as females.

Having such results, made Featherstone to declare that "it was amazing. 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."
Featherstone stated also that humans have a similar gene but it is unclear if this gene might have an effect on humans.