Fruit Fly Homosexuality Study Likely To Prove Controversial
by 365Gay.com Newscenter Staff
Posted: December 10, 2007 - 8:00 am ET
(Chicago, Illinois) While the biological basis for homosexuality remains a mystery, a team of neurobiologists says it may be closer to an answer.
The team led by University of Illinois at Chicago researcher David Featherstone says it has discovered that sexual orientation in fruit flies is controlled by a previously unknown regulator of synapse strength.
Armed with this knowledge, the researchers claim they were able to use either genetic manipulation or drugs to turn the flies' homosexual behavior on and off within hours.
The research will appear in the January issue of Nature Neuroscience the university said.
Featherstone, associate professor of biological sciences at UIC, and his coworkers discovered a gene in fruit flies they called "genderblind," or GB. A mutation in GB turns flies bisexual.
Featherstone found the gene interesting initially because it has the unusual ability to transport the neurotransmitter glutamate out of glial cells -- cells that support and nourish nerve cells but do not fire like neurons do. Previous work from his laboratory showed that changing the amount of glutamate outside cells can change the strength of nerve cell junctions, or synapses, which play a key role in human and animal behavior.
But the GB gene became even more interesting when post-doctoral researcher Yael Grosjean noticed that all the GB mutant male flies were courting other males.
"It was very dramatic," said Featherstone.
The GB mutant males, he said, treated other males exactly the same way nonmutant male flies would treat a female. They even attempted copulation Featherstone said.
Other genes that alter sexual orientation have been described, but most just control whether the brain develops as genetically male or female. It's still unknown why a male brain chooses to do male things and a female brain does female things. The discovery of GB provided an opportunity to understand why males choose to mate with females.
"Based on our previous work, we reasoned that GB mutants might show homosexual behavior because their glutamatergic synapses were altered in some way," said Featherstone. Specifically, the GB mutant synapses might be stronger.
"Homosexual courtship might be sort of an 'overreaction' to sexual stimuli," he explained.
To test this, he and his colleagues genetically altered synapse strength independent of GB, and also fed the flies drugs that can alter synapse strength. As predicted, they were able to turn fly homosexuality on and off -- and within hours.
"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," he said. "This fundamentally changes how we think about this behavior."
Featherstone and his colleagues reasoned that adult fly brains have dual-track sensory circuits, one that triggers heterosexual behavior, the other homosexual. When GB suppresses glutamatergic synapses, the homosexual circuit is blocked.
Meanwhile, a new book by a British anthropologist is likely to be equally controversial.
Desmond Morris, who previously wrote The Naked Ape, claims in his new book The Naked Man that some men are gay because they failed to break the 'boys together' stage of childhood.
That claims Morris results in gay men being more playful and experimental and leads to gays being more artistic.
"Gays have in general made a disproportionately greater contribution to life than nongays," he writes, pointing to gays like Socrates, Leonardo da Vinci, Tchaikovsky, Cole Porter and Oscar Wilde.
