Turning Homosexuality On and Off - TierneyLab - Science - New York Times Blog
In fruit flies, homosexuality is biological but not hard-wired
Public release date: 9-Dec-2007
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Contact: Paul Francuch
francuch@uic.edu
312-996-3457
University of Illinois at Chicago
In fruit flies, homosexuality is biological but not hard-wired
While the biological basis for homosexuality remains a mystery, a team of neurobiologists reports they may have closed in on an answer – by a nose.
The team led by University of Illinois at Chicago researcher David Featherstone has discovered that sexual orientation in fruit flies is controlled by a previously unknown regulator of synapse strength. Armed with this knowledge, the researchers found they were able to use either genetic manipulation or drugs to turn the flies’ homosexual behavior on and off within hours.
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 treated other males exactly the same way normal male flies would treat a female. They even attempted copulation.”
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.
Further work showed precisely how this happens – without GB to suppress synapse strength, the flies no longer interpreted smells the same way.
“Pheromones are powerful sexual stimuli,” Featherstone said. “As it turns out, the GB mutant flies were perceiving pheromones differently. Specifically, the GB mutant males were no longer recognizing male pheromones as a repulsive stimulus.”
Featherstone says it may someday be possible to domesticate insects such as fruit flies and manipulate their sense of smell to turn them into useful pollinators rather than costly pests.
with out my tax money going to waste, i can say my uncle’s are born gay. But sure i will swat a fruit fly without bias,…dead… until then they will wear thongs and be attracted to male phero’s. they are hard-core gaylord’s. It’s almost like the research they always do with blonde’s or college students. great piece though.. anyway, it sounds like they haven’t found a gay fly to study.almost like a cranial castration. i’ll keep my fly swatter handy. I can’t wait till we gay the mosquito population
Brilliant citation, thanks for finding this PQ.
Right now, in my aching head the question arises:
Glutamate…hmn…what for do we use it in modern society?
May it as well be the rising popularity of androgyns has to do somethin’ with polution of food and much more asian food consumption?
I remind mommy uses it for cookies. Darn, does she turn me gay with X-Mas cookies? What satanical circumstances this would be…
Ach well, the scientists do talk of fruit flies and we humans still have 2% other genes or sumthin like that. Hopefully we work in other ways.
Interessting to read, anyway.
Greetings, thy olde Olo
//postscriptum: no, I’m not showing homophobia here, its just that I’d rather would like to stick with women 
My first thought was this provides more ammo for JV Kohl…
>Specifically, the GB mutant males were no longer recognizing male pheromones as a repulsive stimulus."
I was thinking about ths a lot as I came across this study in New Scientist the other day.
And reading around on here, specifically about the different vibe you get in gay bars as opposed to straight ones, and how a straight male will get all wound up and aggressive just seeing another male whereas gay males won’t..
I was wondering if males were gay by default, but in straight guys the male/male repulsion overcame this impulse.
Thing is, if that were true and it was all done by scent, if you had a blocked nose, you would turn gay.
Still, I’ve noticed the only straight males I know who do not get all antsy at the sight of a male (who isn’t one of their pals) are all exceptionally gentle guys. Complete chick magnets too because they are very sensitive to other people’s feelings.
This male to male agression - until I did some reading on here I didn’t know it was a part of their biology - I just thought I knew a lot of guys who were a bit insecure, though I was puzzled as to why it was mostly the older ones, and how all my older male friends would take an instant and lasting dislike to my younger male friends. Beyond all reason sometimes. I’ve had to bash a lot of heads together.
F.
insightful post - thanks.
jvkohl - conditioning…
care to elaborate on this?
PQ.
Yeah, girls dont want a jerk, real girls who want relationships are repulsed by someone who considers themselves a “player” or by someone who wants to display themselves as being better or by bragging about how well them can fight. They also want someone who understands them EMOTIONALLY, and the guys who actually can actually want the same thing even if others guys jst want someone cute and playful, or someone with certain personlity traits. There are girls who do like guys who are not like this but those are the girls who will have sex with anybody or girls who just want someone to “have fun” with (that is, to go to the movies and hang out and to say “I have a boyfriend,” but they would not actually be upset for more then a few days if you died). But, I dont see how you need to elaborate on what he said - there isnt really much to elaborate on. Anyway:
Just because something can be altered by a drug does not mean it is hard wired. Also whatever drug they were giving, may have just made the flies exceptionally horny; most animals have no way to masturbate for example. So do we know, were they putting those flies around a bunch of other males or were both the males and females within equal reach and both equally accessible? Also were the females rejecting them?
If they ever released a drug like that, it would be useful for those people who are extreme Christains and who hate themselves because they are gay (this type of person who was made fun of in an episode of The Simpsons tried to kill himself until another character said, “Why shouldnt we be gay” and he said “Youre right” and then stopped trying to kill himself). But we would also have the much bigger problem of people, especially parents, using these drugs on other people who are not themselves, and then even BIGGER problem of certian psychologists and therapists who tihnk they are better then some people actually PERSCRIBING these drugs - they would have more ammo trying to tell a person they are wrong or bad, and if the person believs them they will actually cause the depression, or they will cause an anger which could also cause depression.
These researchers are forgetting one very important thing, though. Most human females can get turned on by other females talking about sex, or, if not, they wont get turned OFF at least if another female is naked in the room. Most females WILL get turned on if another female is masturbating in their presence, and most females would feel something sexual if another female were to touch them sexually - in that case it’s for the same reasons a vibrator (which is also not male) would make you feel something. However most females are also not gay (in my experience there are actually more gay males then gay females, but I dont know if thats true on a larger scale or if its just true in my own life). Human sexual orientation has another factor that is not present in fruit flies or in any other animal except possibly dolphins - love. Human sexuality is usually determined by who you can fall in love with, except for people who are not capable of that type of love, or in people who have sex with lots of different people in a week and are not currently in love. Like I said most females would be stimulated if another female started touching them the right way - and males would too if say there was a gay guy dressed up as a female so the guy’s concious mind was not repelled by knowing he is male (a common skit for sitcoms or screwball comedies). Most people’s sexual orientation has more to do with love then sexual.