Male and female fruitflies have been engineered to switch courtship roles, through the manipulation of a single gene.
The study, which appears in Cell, shows how a simple genetic adjustment can cause a dramatic change in sexual behaviour. "It was quite something to see," says Barry Dickson, who is one of the authors and is based at the Austrian Academy of Sciences in Vienna.
The mating behaviours of the Drosophila fruitfly are a far cry from intricate Hollywood romance. The male performs a series of tapping and tilting movements, to which the female usually responds if she has not recently mated. Females, in contrast, never court at all.
But Dickson and his colleague Ebru Demir reversed this behaviour by designing female flies with the male version of a gene called fruitless. These insects initiated courtship with other females as often as their male counterparts did. The tweaked female flies could only be encouraged to court males if the males were designed to emit female pheromones, a form of natural chemical attractant.
When male flies were given the female version of the fruitless gene, they stopped courting and became passive about sex.
Unleash the essentialist hounds! Of course, just because the fruit fly has a remarkably simple mechanism for mating behavior does not mean that it give us much insight into human sexual orientation. Or even other creatures of fur and feather for that matter.
But the researchers caution that controls on a fruitfly's sexual behaviour are undoubtedly different from our own. "In the case of humans, we know that our sexual behaviours are not irreversibly set by our genes," says Dickson. "But that doesn't mean the genes have no influence," he adds.So for now, what we have is simply a way for scientists in a lab to turn fruit flies queer. Sounds fun, guys. Shall I bring the beer?
"There's still a lot of mystery surrounding the causes of homosexuality," says Hans Van Gossum of the University of Antwerp, Belgium, who has studied fly mating patterns. "It's too early to draw strong conclusions on simple mechanisms like this."