Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Transistor in the Fly Antenna: Insect odorant receptors regulate their own sensitivity

18.03.2013
Highly developed antennae containing different types of olfactory receptors allow insects to use minute amounts of odors for orientation towards resources like food, oviposition sites or mates.
Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now provided experimental proof that the extremely sensitive olfactory system of fruit flies is based on self-regulation of odorant receptors. Even a below threshold odor stimulation increases the sensitivity of the receptor, and if a second odor pulse arrives within a certain time span, a neural response will be elicited.

Highly developed antennae containing different types of olfactory receptors allow insects to use minute amounts of odors for orientation towards resources like food, oviposition sites or mates. Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now used mutant flies and for the first time provided experimental proof that the extremely sensitive olfactory system of fruit flies − they are able to detect a few thousand odor molecules per milliliter of air, whereas humans need hundreds of millions − is based on self-regulation of odorant receptors.

The antennae of the fruit fly Drosophila melanogaster, shown schematically in dark yellow. Dark red: odor molecules. Right: The odorant receptors studied are protein dimers consisting of the odorant receptor Or22a and the co-receptor Orco; they mediate very sensitive responses to odor molecules. Above: State of sensitization − weak ion flow caused by cAMP; below: signals are “switched through” in the receptor system resulting in opening of the ion channel and electric signal transduction. The pictures are taken from the animation.

Graphics: Dieter Wicher, Max Planck Institute for Chemical Ecology. Animation: Moves Like Nature, Kimberly Falk

Even fewer molecules below the response threshold are sufficient to amplify the sensitivity of the receptors, and binding of molecules shortly afterwards triggers the opening of an ion channel that controls the fly’s reaction and flight behavior. This means that a below threshold odor stimulation increases the sensitivity of the receptor, and if a second odor pulse arrives within a certain time span, a neural response will be elicited. (PLOS ONE, March 12, 2013, DOI: 10.1371/journal.pone.0058889)

A sensitive sense of smell is vital

It is amazing how many fruit flies (Drosophila melanogaster) find their way to a rotting apple. It is known that insects are able to detect the slightest concentrations of odor molecules, especially pheromones, but also “food signals”.

Dieter Wicher, Bill Hansson and their colleagues at the Max Planck Institute for Chemical Ecology were looking for answers to the question why insects can trace odor molecules so easily and at such low concentrations in comparison to other animals. They focused their attention on odorant receptor proteins in the antenna, the insects’ nose. These insect proteins are pretty young from an evolutionary perspective and their molecular constituents may be the basis for the insects’ highly sensitive sense of smell.

Receptor system Or22a-Orco

Insect odorant receptors form a receptor system that consists of the actual receptor protein and an ion channel. After binding of an odor molecule, receptor protein and ion channel trigger the neural electrical response. This mechanism was recently described in the receptor system Or22a-Orco (Wicher et al., Nature 452, 2008); Sato et al., Nature 452, 2008). Apart from functioning as so-called ionotropic receptors, which enable ion flow through membranes after binding of odor molecules, odorant receptors also elicit intracellular signals. These stimulate the formation of cyclic adenosine monophosphate (cyclic AMP or cAMP), which activates an ion flow through the co-receptor Orco. The role and relevance of this weak and slow electrical current, however, was until now unclear.

Drosophila mutant Orco mut

Merid N. Getahun, a PhD student from Ethiopia, and his colleagues have conducted numerous experiments on Drosophila olfactory neurons. They injected tiny amounts of compounds that stimulate, inhibit or imitate cAMP formation directly into the sensory hairs housing olfactory sensory neurons on the fly antenna. The researchers tested the flies’ responses to ethyl butyrate, which has a fruity odor similar to pineapple, and measured activity in the sensory neurons by using glass microelectrodes. As a control, they used genetically modified fruit flies where the co-receptor Orco had been inactivated. “The fact that these mutants are no more able to respond to cAMP or the inhibition/activation of the involved key enzymes, such as protein kinase C and phospholipase C, shows that the highly sensitive olfactory system in insects is regulated intracellularly by their own odorant receptors,” says Dieter Wicher, the leader of the research group. The combination of odorant receptor and co-receptor Orco can be compared to a transistor, Wicher continues: A weak basic current is sufficient to release the main electric current that activates the neuron. The process can also be seen as a short-term memory situated in the insect nose. A very weak stimulus does not elicit a response when it first occurs, but if it reoccurs within a certain time span it will release the electrical response according to the principle “one time is no time, but two is a bunch.” [JWK/AO]

Original Publication:
Merid N. Getahun, Shannon B. Olsson, Sofia Lavista-Llanos, Bill S. Hansson, Dieter Wicher: Insect odorant response sensitivity is tuned by metabotropically autoregulated olfactory receptors. PLOS ONE, March 12, 2013; DOI: 10.1371/journal.pone.0058889
http://dx.doi.org/10.1371/journal.pone.0058889

Further Information:
Priv. Doz. Dr. Dieter Wicher, +49 3641 57-1415, dwicher@ice.mpg.de

Picture Requests:
Angela Overmeyer M.A., +49 3641 57-2110, overmeyer@ice.mpg.de
or Download via http://www.ice.mpg.de/ext/735.html

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/1017.html?&L=0

More articles from Life Sciences:

nachricht Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)

nachricht Self-assembled nanostructures hit their target
23.09.2016 | King Abdullah University of Science and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Chains of nanogold – forged with atomic precision

23.09.2016 | Life Sciences

New leukemia treatment offers hope

23.09.2016 | Health and Medicine

Self-assembled nanostructures hit their target

23.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>