When female flies smell their favorite food, they become more receptive to courting males.
“A way to someone’s heart is through their stomach” is a popular saying. But it is not only in humans that romance and a good dinner seem to go together well. In the vinegar fly Drosophila melanogaster, scientists from the Max Planck Institute for Chemical Ecology have now even identified the respective underlying neuronal mechanism in the fly’s brain. If vinegar is nearby, male flies are perceived as more attractive and the receptivity of virgin females towards courting males is increased.
Vinegar odor boosts the perception of a male sex pheromone in the brain of unmated female Drosophila melanogaster flies, as a team of scientists from the Department of Evolutionary Neuroethology has now discovered.
The researchers were able to identify the underlying neuronal mechanism in the brain of Drosophila flies. Previous experiments had revealed that the male pheromone cis-vaccenyl acetate activates the glomerulus DA1 in the brains of female flies. Glomeruli are spherical functional units in the antennal lobe, the olfactory center in the fly brain.
“We were able to show in our study that vinegar odor enhances the reactions of female flies to the male sex pheromone significantly. Both odors together intensify the activation of DA1,” explains Silke Sachse, head of the “Olfactory Coding” research group. The scientists observed this effect only in unmated virgin flies; it was absent in males and mated females.
Analyzing the underlying neural mechanisms, the neurobiologists were able to elucidate how the odor signals were processed in the fly brain and determine which brain areas were activated. They used functional imaging techniques to monitor and visualize brain activity induced by the sex pheromone, by vinegar, and by both odors together.
Transgenic fly lines were crucial for the experiments. In these flies, selected electrical synapses -- connections between specific classes of nerve cells -- had been silenced. The various lines helped researchers pinpoint the neurons involved in signal transfer and to precisely locate the neuronal site of the interaction of two odors.
“We were able to show that the enhanced activation of the glomerulus DA1 is mediated by a so-called “lateral excitation” in a particular class of neurons. Different neighboring glomeruli in the brain respond to the odor of vinegar, and the excitation from those glomeruli is transmitted to DA1 via electrical synapses,” says first author, Sudeshna Das, who came to the Max Planck Institute as a fellow from the Alexander von Humboldt Foundation.
The male sex pheromone, in contrast to the vinegar, activates DA1 directly through the specialized olfactory receptor Or67d. Thus both odors activate the same olfactory glomerulus, just through different neuronal pathways. Together, the scents evoke an enhanced behavioral response in virgin females, increasing their willingness to mate.
From an ecological perspective, this mechanism is extremely important, because it accelerates mating when sufficient food is available for the females and for their offspring. “We were surprised that this strong response enhancement of the pheromone response by vinegar is completely absent in mated female flies. However, after discovering the behavioral relevance for courtship we realized that this effect only makes sense in virgin females,” says Silke Sachse.
The increased willingness to mate in the presence of sufficient food is important with respect to reproductive success, which is probably why this rare synergistic interaction between the responses to two different odors has evolved. “A synergistic interaction of two odors is extremely rare and has hardly been observed so far. The more general rule is that different odors rather inhibit each other and lead to mixture inhibition which allows the olfactory system not to become saturated when more than one odor is perceived,” Silke Sachse emphasizes.
The results have also further ecological relevance: “In nature, female flies only perceive little amounts of the male sex pheromone. From an evolutionary point of view it seems useful that they evolved a mechanism which enhances the effect of the pheromone without the males having to release higher concentrations. If you consider that Drosophila flies have a pretty short life span during which they are constantly threatened by predators, infections or toxic food, accelerated mating and reproduction is very important for their survival,” says Sudeshna Das. [AO/KG]
Das, S., Trona, F., Khallaf, M. A., Schuh, E., Knaden, M., Hansson, B. S.. Sachse, S. (2017). Electrical synapses mediate synergism between pheromone and food odors in Drosophila melanogaster. Proceedings of the National Academy of Sciences of the United States of America, Early Edition, DOI: 10.1073/pnas.1712706114
Dr. Silke Sachse, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-1405, E-Mail firstname.lastname@example.org
Contact and Media Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail email@example.com
Download high-resolution images via http://www.ice.mpg.de/ext/downloads2017.html
Department of Evolutionary Neuroethology http://www.ice.mpg.de/ext/index.php?id=evolutionary-neuroethology&L=0
Angela Overmeyer | Max-Planck-Institut für chemische Ökologie
New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego
Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Ecology, The Environment and Conservation
17.01.2018 | Physics and Astronomy
17.01.2018 | Awards Funding