Field of Science

Why Would You Get Flies Pissed ? (Or why I shouldn't take news articles at face value)

On my daily scan of internet news, I read an astounding piece of news. Drunk flies become "homosexual". when I read about something like this I often wonder two things:

  1. What was the point of doing this
  2. Why did someone come along and decide that this is "news"

So I dug deeper to find out why this piece of research was done. (I would rather have a slightly informed opinion on a piece of research than a completely uninformed reason)

Why was this experiment done?

The point of this experiment was to find out how alcohol affects flies level of sexual arousal. My immediate reaction to this is "who cares how it affects flies". But the point of this article is not to give people an excuse to open up Rehab clinics around the country for chronically depressed flies. Nobody really cares about flies. it's not as if they are a helpless species.

The point of this research was so that we can find out more about why we react so badly to alcohol. At this point I often find myself saying "yes, but humans are not flies, so again, what is the point of doing this experiment? Why not do it on mice, or apes, or even Humans?"
There are four reasons why you would do this experiment on flies instead of mice/humans/other experimental animals:
  1. Costs: The cost of using laboratory animals and/or people in in experiments are quite high. Making sure that they are kept healthy and happy throughout the experiment will drain money out of a scientists research grant very quickly.
  2. Ethics: people don't seem to regard ethics as applying to flies, for some reason, probably the same reason that the Centre for Disease Control doesn't often get firebombed by the Bacterial Liberation Front.
  3. Genetic Variability: The thing that is good about using flies for experiments is that their entire genome has been sequenced. This is probably the most important reason as to why flies were used in this experiment. One big problem in experimental trial in humans is that genetically, we are very diverse. The way we respond to alcohol is in part determined by our genes. Since everyone has different genes, this means that people react differently to alcohol. In flies however, scientists can "breed out" genetic variability. So all the flies have the same genes, and so will react to the alcohol treatment in the same way.
  4. Short Life Cycle: One thing people hate more than anything is an experiment that takes a long time. When a company employs people in a lab, they don't want to hear "it'll be about a few hundred years until we get any useful results". And if we are talking about testing on humans, that is how long it would take. The human genome isn't even finished properly yet. And if you told an ethics committee that you want to inbreed humans for your experiments, they would collectively drop a brick . But you can inbreed flies without anyone really complaining (as long as you are doing it for something useful, not just for fun, like people who breed poodles) and with the bonus that it won't take very long, because the life cycle of a fly is very short, about seven days.
So these are all very good, but what evidence do we have that flies will react to alcohol in the same way as humans do? Getting drunk is not a universal thing that happens to all creation. you can't get plants drunk. bacteria tend to die when you give them too much alcohol.
Well, luckily a previous experiment was done [2] which showed that flies respond in a similar way to humans when they get drunk i.e. they lose their motor co-ordination (they stagger about a bit) , they become hyperactive (they stagger about a LOT) ,if they drink a lot, they can become tolerant to alcohol ( like the real heavyweight drinkers do) and if they drink a helluva lot, they drop dead.
(Shit joke : There have been other experiments to see how flies react to methamphetamine and cocaine [3]. Apparently, they were buzzing. )
Anyway, the reason we humans respond to alcohol in the way that we do is because alcohol reacts with certain brain proteins [3] although it is not known how the reactions with these proteins actually cause drunkenness. It is thought that alcohol reacts with similar proteins in the brains of flies.
Why is this news ?
This is reportable news because in science at the moment, it is not conclusively known how alcohol affects your brain physiologically in order to make you more randy. What they did here was use a heat sensitive dopamine releasing gene i.e. dopamine was only released into the brains of these flies unless the temperature exceeds 30 degrees Celsius. What they found was that in flies that were made drunk, and where they had dopamine inhibited, there was less sexual activity. This may be one of the first studies in which this is conclusively proven (I don't know whether this is true, i'm not an expert). What this study shows is that the dopamine pathway is a key component in explaining why people can get randy after a few skinfuls.
However, the one thing this report does NOT say, but was insinuated by (let's face it ) me was that drinking turns flies gay, which is not true. At most, it causes a state of "genderblindness" in some flies, as long as they have mutations within certain specific genes. Which basically shows that I shouldn't read headlines off newspapers and assume they are the truth.

  1. Recurring Ethanol Exposure Induces Disinhibited Courtship in Drosophila
    Hyun-Gwan Lee
    1, Young-Cho Kim2, Jennifer S. Dunning3, Kyung-An Han1,2* DOI: 10.1371/journal.pone.0001391
  2. Functional Ethanol Tolerance in Drosophila
    Henrike Scholz
    , , 1, , Jennifer Ramond4, Carol M. Singh2 and Ulrike Heberlein doi:10.1016/S0896-6273(00)00101-X
  3. Invertebrate models of drug abuse, Fred W. Wolf *, Ulrike Heberlein, DOI:10.1002/neu.10166
  4. Behavioral analysis of male rat sexual motivation and performance following acute ethanol treatment Ferraro FM 3rd, Kiefer SW .doi:10.1016/j.pbb.2004.03.020

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