Gene change alters sex orientation in fruit flies 

NEW YORK (Reuters) - Altering a single gene in a fruit fly can turn its sexual orientation around, causing male flies to lose interest in females, and females to display male mating rituals to other females, according to a study published in the journal Cell on Friday. 

The research by Barry J. Dickson and Ebru Demir of the Institute of Molecular Biotechnology of the Austrian Academy of Sciences into the workings of a "switch gene" touched on the scientific debate about whether genes or environment determine human sexual orientation.

Male courtship in Drosophila is an elaborate ritual and largely a fixed-action pattern easily identified by the researchers. The male taps the female with his forelegs, sings a specific courtship song by extending and vibrating a wing, licks her genitalia, and then curls his abdomen for copulation.

Through gene splicing, they were able to swap the orientation of male and female fruit flies they studied in an observation chamber.

"Forcing female splicing in the male results in a loss of male courtship behavior and orientation," the study said. "More dramatically, females ... spliced in the male mode behave as if they were males: they court other females. A complex innate behavior is thus specified by the action of a single gene, demonstrating that behavioral switch genes do indeed exist."

Female flies with the male version of the gene also made amorous advances toward male flies expressing female pheromones, while altered male flies were more likely to court other males. 

So-called "switch genes" that trigger development of an anatomical feature such as wing structure have been extensively studied, but there a few studies of switch genes that control a complex behavior, the researchers said.

The researchers said they have already begun work with other scientists to test for switch genes that might be linked to other behavioral patterns like aggression. 

辅助阅读：

据路透社消息，上周五在Cell 杂志上发表的一篇论文称，改变果蝇的一个基因可改变其性取向，使雄果蝇对雌果蝇失去兴趣，而使雌果蝇对其他雌果蝇摆出类似雄果蝇的交配姿态。

该项由奥地利科学院分子生物科学研究所的Barry J. Dickson和Ebru Demir进行的研究引起了关于基因或环境是否决定人类的性取向这一问题的争论。