Fruity Flies

November 24, 2010

Brit Trogen

Picture a manly male. He's a little aggressive, the first to initiate courtship. And of course he's got a nice row of sexcombs to go with that black patch on his abdomen. What female could resist a stud like that?


Science in Seconds Brit Trogen


Courtship in flies involves a series of well-documented behaviors, mostly initiated by the male. The winged Casanova chases some uninterested female, wooing her with tapping, licking, and vibrating his wings to create a "courtship" song. In successful cases, the female will slow down enough to be receptive and allow copulation. Let's stop there for a moment. Tapping? Licking? A courtship song? If only every man were so romantic.


When it comes to the study of sex and gender, there's no better model organism than the fruit fly. All it really takes is a little tweaking with their genetic makeup and you can make anything: "feminine" males that attract the attention of other males, "masculine" females that appear unattractive to other males, even flies that fail to produce any external genitalia at all (the mutation that produces that one? The aptly named Ken and Barbie.) But researchers at Harvard Medical School have now found that when it comes to the "male-" or "female-ness" of flies, it's not just how you look or act. Smelling like your sex is just as important as anything else. According to a study published in this week's PLoS Biology, pheromonal clues that are expressed as body-surface hydrocarbons play a major role in helping males determine whether a fly is a potential mate, or competition.


A sexual determination factor called transformer was used to observe this effect, switching pheromone expression between males and females. The result? "Masculine"-smelling females who were attacked by nearby males, rather than courted by them. Talk about being threatened by alpha-females...


The gene doublesex alters brain architecture in a similar way, working with another gene called fruitless to cause a switch in behavioral cues between males and females. Dsx females engage in certain courtship behaviors with other females, and reject copulation with males, while the dsx males remain, well, fruitless. 


Ahh, the brains of flies. So simple, so easy to manipulate. Is there anything we can't do? 


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Fernández, M., Chan, Y., Yew, J., Billeter, J., Dreisewerd, K., Levine, J., & Kravitz, E. (2010). Pheromonal and Behavioral Cues Trigger Male-to-Female Aggression in Drosophila PLoS Biology, 8 (11) DOI: 10.1371/journal.pbio.1000541



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