Tag Archives: Drosophila melanogaster


Currently, there is a housefly buzzing around my head. Every single time it lands I attempt this futile clapping motion to destroy it. I fail. I fail time and time again. So, my question is, obviously, WHY CAN’T I HIT YOU!?

After a small amount of Google-sleuthing I found the answer here. It seems Drosophila contain a pair of large aptly named nerves, Giant Fiber. This bundle runs the entire length of the head and down to the thorax. At the endpoint it triggers the thoracic ganglion which then shoots elsewhere. What triggers this giant bundle to begin with? The eyes! It uses visual cues to initiate its escape sequence. I wonder why it would be associated with something like that…

Just an eye... NBDSo if the Giant Fibers end with the thoracic ganglion what happens next? The ganglion shoots the signal to the dorsal longitudinal muscle (DLM) and tergotrochanteral muscle (TTM or “jump muscles”). This moves two thing: the legs and the wings. What do the legs do? JUMP! Thus, the reason they’re called jump muscles. The wings do something a little more complex. Upon receiving a signal  the wings go from the closed position to the open position and slightly elevate. So really the one nerve bundle initiates a double whammy of legs and wings. The strange part is that the TTM does both of these functions. The DLM is only indirectly involved.

So the take away message is that a simple little pathway is why I can’t kill this damn fly.

Sidenote, the paper is a little dated as it was published in 1983 but the general workings are still the same.


Flies didn’t evolve around flyswatters. Gotcha.Owned.


Sexual Dimorphism in Drosophila

Last week, Current Biology released an article about structural differences between sexes in Drosophila melanogaster. It may not be about a human brain, but it’s still neurology and at least semi-related to developmental biology this time.

While the “model” organism displays distinct behavioral differences between sexes, the overall anatomy in regards to dimorphism has been essentially neglected. Previously, the only discernible difference was in the olfactory system. Male olfactory systems have a 25 – 60% larger volume than female flies. Coincidently the male pheromone cVA attracts females while repelling males (however no credible correlation can be made).

Ooooo pretty!

Pretty picture! This is one of many from a collage presented in the article and most interesting to myself as it visibly shows the gender difference in brain size. Magenta is larger in females and green is larger in males.

The article proceeds to explain the fine tunings of specific proteins (fruitless, sex lethal, and transformer) and their effect on dimorphism in a manner that is, quite frankly, far beyond my level of comprehension.

Overall, sexual dimorphism does exist in the Drosophila brain and may influence behavior as a result. A key example of this lies in the activation of fruM (the male version of the fruitless protein) in females and the resulting behavior of courting other females. Now that the anatomical groundwork has been laid the researchers are able to pursue behavioral consequences in future research.

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