Fine-tuning sense of smell helps fruit flies find their mates

July 31st, 2008 - 1:55 pm ICT by ANI  

Washington, July 31 (ANI): When it comes to finding a mate, fruit files dont require good looks, for fine-tuning of their olfactory systems is more than enough to do the magical trick, says a new study.

Neurobiologists at UC San Diego, Stockholm University and the National Institute of Child Health and Human Development have shown that fruit flies fine-tune their olfactory systems by recalibrating the sensitivity of different odor channels in response to changing concentrations of environmental cues.

Disable this calibration system, and flies have trouble finding a mate, the researchers added.

The researcher team has evidence that the fly nervous system can dampen its response to intense smells to prevent strong signals from overloading the circuits, they report in the July 31 issue of Neuron.

“We found a feedback mechanism in the olfactory system,” said Jing Wang, assistant professor of biology at UCSD and senior author of the paper.

“This system may be useful for the fly to navigate the olfactory landscape. Odor concentrations can change very dramatically, and this is how they deal it, Jing added.

Olfactory neurons selectively respond to particular chemicals, such as ethyl hexanoate, which smells like ripe bananas, or food to a fruit fly.

“We applied natural odors to the antennae, odors that the fly would normally smell,” said Cory Root, a graduate student in biology at UCSD and first author of the paper.

When Root wafted concentrated banana smell onto the flies” antennae, he found increases in signaling by a molecule called the GABAB receptor, which helps to inhibit neurons from sending signals, and he confirmed that cells with increased signaling by GABAB receptors released neurotransmitter less easily.

Other strong fruity smells and a male pheromone, a chemical sex attractant, also shifted subsequent neural responses to those stimulants, adjusting the response range to detect differences between higher levels of these odors.

But carbon dioxide, a stress signal in flies, shifted the response very little.

When the team knocked down levels of the receptor molecule within the specific olfactory neurons tuned to pheromones using molecular biological techniques they found that the fly neural system failed to adjust to chemical overloads. And without the fine tuning, male flies had difficulty finding females. (ANI)

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