Brains, Sex and Fruitflies

From PhysOrg :

In a paper published today in the journal Nature Neuroscience, researchers from the University of Glasgow and the University of Oxford, have shown that the gene known as 'doublesex' (dsx), which determines the shape and structure of the male and female body in the fruit fly, also sculpts the architecture of their brain and nervous system, resulting in sex-specific behaviours.

The courtship behaviour of the fruit fly has long been used to study the relationship between genes and behaviour: it is innate, manifesting in a series of stereotypical behaviours largely performed by the male.
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"The dogma was that (the gene) dsx made fruit flies look the way they did and fru made them behave the way they did," explains Dr Stephen Goodwin from the University of Oxford, who led the research. "We now know that this is not true. dsx and fru act together to form the neuronal networks - the wiring - for sexual behaviour."

ru has so far been found only in insects; dsx, however, is found throughout the animal kingdom, where it plays a fundamental role in sex determination, and so is of particular interest to researchers.

Using a transgenic tool generated in his lab, Dr Goodwin and colleagues were able to map dsx throughout the fly's development using a fluorescent protein marker that illuminates areas where DSX is active. This highlighted profound differences in neural architecture between the sexes. In males, the researchers were able to show that dsx complements fru activity to create a 'shared' male-specific neural circuit; in females (where fru is inactive), dsx forms a female-specific circuit.
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Importantly the researchers were able to manipulate these cells, impinging their ability to function, and show that these circuits are responsible for behaviours unique to the individual sexes.

"It has been suggested that there are only minor trivial differences between the neural circuits that underlie behaviour in males and females," explains Dr Goodwin. "We have shown that in fact there is quite a bit of difference in the number of neurons and how these neurons connect, or 'talk', to each other. These differences can have big consequences on the structure and function of the nervous system."

Just remember - we're only talking about fruit-flies here. We sgould be cautious about over-generalisation.

Interesting though, isn'y it?