Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Olfactory nerve cells expressing same receptor display a varied set of reactions

03.02.2006


Findings help researchers revise models of mammalian sense of smell


Composite of olfactory neuron response to lyral odor. The background shows intact olfactory neuroepithelium containing MOR23 cells tagged with GFP (green fluorescent protein). The right upper corner shows dendritic knob and cilia from a single MOR23 neuron. The left lower corner shows the electrical responses over time of a single MOR23 cell to lyral, the ligand for MOR23, at different concentrations. (Credit: Xavier Grosmaitre and Minghong Ma, PhD, University of Pennsylvania School of Medicine)



In a mouse model, University of Pennsylvania School of Medicine researchers discovered that olfactory sensory neurons expressing the same receptor responded to a specific odor with an array of speeds and sensitivities, a phenomenon previously not detected in the mammalian sense of smell. The group published their findings this week in the online edition of the Proceedings of the National Academy of Sciences.

"We assumed that the sensory neurons that express the same receptor would respond to a specific odor in the same way," says senior author Minghong Ma, PhD, Assistant Professor of Neuroscience at Penn. "But in real biology, these olfactory neurons keep regenerating, and even though they all express the same receptor, they’re probably at different states of maturation, displaying different qualities. By knowing that olfactory neurons can respond differently, we’re adding another layer to understanding how the olfactory system receives outside information."


Ma’s group measured 53 different olfactory neurons that express the MOR23 odor receptor. As a group, the neurons reacted differently from one another in their response to lyral, an artificial odor used in fragrances and flavoring. After subjecting all cells to a short pulse (200-300 milliseconds) of lyral, the researchers measured the cells’ sensitivity to the odor. Some cells responded to very low concentrations of lyral; others, to higher concentrations. Regarding the cells’ reaction time, some neurons finished firing within 500 milliseconds, but for others, the response time was up to five seconds.

Detection of odor molecules depends on about 1000 different odor receptors in the rodent nose. Different sets of receptors respond to different sets of odors. To date, no one has been able to record electrical impulses from a specific subtype of olfactory sensory neuron expressing a known receptor. This is important, says Ma, because prior to this paper, when researchers would work with olfactory cells, there was no way to know what odor receptor that cell expressed. "It could literally be one out of 1000," she says.

All the sensory neurons expressing the same receptor merge to a common region called a glomerulus, a region in the brain’s olfactory bulb. In one bulb there are about 2000 glomeruli. (The brain has two olfactory bulbs.) There are thousands of sensory neurons dedicated to expressing the same receptor, and in the case of MOR23 they all merge to two glomeruli.

The researchers used genetically engineered mice that express MOR23 together with green fluorescent protein (GFP), which was generated by colleagues from Rockefeller University. The GFP allows the investigators to visualize the MOR23 cells separate from other neurons. They also recorded their measurements using cells still intact within the lining of the nose, which allows the researchers to study these cells in their natural biochemical environment.

The researchers made their measurements from the endings of olfactory neuron dendrites. A single dendrite extends from the cell body of the olfactory neuron into the nasal cavity. The dendrite has a swelling at the end called the knob, where about 10 to 15 hair-like extensions called cilia contain the odor receptors.

Ma and colleagues are now working out the implications of their findings. She says this study points to a more finely tuned response in the brain to odors than previously thought. "Olfactory neurons may be able to respond to an even wider range of odor concentrations than we realized," she says. The heterogeneity in odor sensitivity and the wide response range in single cells provides new insights into why mammals, including humans, perceive odors with unchanged quality over a broad concentration range.

Karen Kreeger | EurekAlert!
Further information:
http://www.uphs.upenn.edu

More articles from Studies and Analyses:

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Link Discovered between Immune System, Brain Structure and Memory

26.04.2017 | Life Sciences

New survey hints at exotic origin for the Cold Spot

26.04.2017 | Physics and Astronomy

NASA examines newly formed Tropical Depression 3W in 3-D

26.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>