Girlie fly necroMANIA!

You have to have a pretty weird science story to get traction this week, and Reuters serves one up:

Gene swap makes boy flies fight like girls
The researchers swapped the male and female versions of the gene in fruit flies and observed the consequences. Males with the feminine gene used female fighting tactics, while the females with the masculine gene fought like the boys.

The story doesn't explain why there are male and female "versions" of the gene, but the actual research by Vrontou et al. sheds some light:

We speculated that the fruitless (fru) gene might be involved in specifying these sex differences in aggression and dominance. This inference was based on fru's critical role in another sex-specific social behavior, male courtship, as well as on an earlier report of anomalous interactions in fru mutant males that were subsequently found to be characteristic of normal female fights. The fru gene produces multiple transcripts, all of which are thought to encode zinc-finger transcription factors. Transcripts from the distal P1 promoter are sex-specifically spliced, resulting in male-specific mRNAs that encode full-length Fru proteins (FruM) and female-specific mRNAs that are evidently not translated. We previously generated alleles of fru that are constitutively spliced in either the male (fruM) or female (fruF) mode, irrespective of the sex of the fly. An additional control allele (fruC) is subject to normal sex-specific splicing.

Anyway, doing the switch-up between the male expressed version and the female nontranslated version causes a reversal of gender roles in these fights. Actually, the research paper has a much more flavorful description of these than the Reuters article:

Under the appropriate conditions, pairs of male or female flies will fight each other, displaying a distinctive set of aggressive behaviors (Supplementary Videos 1 and 2 online). Some of these behavioral components are common to both male and female fights, such as low-intensity 'fencing.' Other components, particularly those of higher intensity, are much more frequent in one sex than the other. For example, 'lunging' and 'boxing' are mostly seen in male fights, whereas 'shoving' and 'head-butting' are characteristic of female fights.

Oh yes, you read that correctly. The supplementary info includes videos.

And how can you not watch with a set-up like this?

They set up the insect world's equivalent to a steel-cage match - a chamber with glass walls and a lid with air holes, a dish of fly food and a mate - and sent in the combatants. But when they used a live female fly as a lure for the males, she often would just fly off.
"My student discovered when he transferred the female to the dish and accidentally crushed her head that the males didn't care whether she had a head or not. That's a true story of what led us to cutting the heads of the females off in subsequent studies," Kravitz said. "They'll court the dead, headless female fly, and try to copulate with her sometimes."

I must admit, it is more interesting than I thought fruit fly fights would end up being. They actually do "box" each other!

I can't tell what they're fighting on, though -- maybe it's one of those new candles from Glah-day...


Vrontou E, Nilsen SP, Demir E, Kravitz EA, Dickson BJ. 2006. fruitless regulates aggression and dominance in Drosophila. Nature Neurosci Early online DOI link